December 17, 2010
THEORY GROUP:R. Betti and R. Davidson attended the first meeting of the National Research Council Inertial Fusion Energy panel in Washington DC on December 16-17.
The paper "Reducing Turbulent Transport in Toroidal Configurations Via Shaping" by Drs. Harry Mynick, Neil Pomphrey, and Pavlos Xanthopoulos (IPP-Greifswald) has been accepted for publication in the Physics of Plasmas.
COMPUTATIONAL PLASMA PHYSICS GROUP
Stephane Ethier gave a hands-on tutorial entitled, "Introduction to Parallel Programming with MPI" at Princeton University as part of the Princeton Institute for Computational Science and Engineering (PICSciE) and the Program in Integrative Information, Computer and Application Sciences (PICASso). as part of the Computer Science Department Program in Integrative Information, Computer and Application Sciences (PICASso). Given annually, this tutorial continues to be very popular amongst Princeton University's graduate students and scientists from all the science departments.
Stephane Ethier is a contributor in the newly published book entitled "Performance Tuning of Scientific Applications" (Chapman & Hall/CRC Computational Science). The chapter on "Large-Scale Numerical Simulations on High-End Computational Platforms" includes Dr. Ethier's work and performance study of the 2D domain decomposition implemented in the global, toroidal gyrokinetic particle-in-cell code GTC-P. This work shows how the 2D domain decomposition can dramatically reduce the memory footprint of large-scale gyrokinetic PIC simulations while improving scalability and performance.
The review article "Review of implicit methods for the magnetohydrodynamic description of magnetically confined plasmas," by S. Jardin, has been accepted for publication by the Journal of Computational Physics (2011). The article traces the roots of modern day implicit algorithms used in fusion 3D extended-MHD codes to developments in the 1960s and 1970s. A preprint of the manuscript is available as PPPL-4559(R).
December 10, 2010
THEORY GROUP
Dr. Harry Mynick presented the Plasma Physics Colloquium at Columbia University on December 3, "Optimizing Toroidal Configurations for Turbulent Transport Via Shaping".Allan Reiman and John Krommes gave a joint Theory Department seminar on, "Calculation of Equilibria with Nonzero Pressure Gradients in Stochastic Regions".
Dr. Choong-Seock Chang and Dr. Seung-Hoe Ku (both at the Courant Institute of Mathematical Sciences, New York University) gave a joint seminar entitled, “Studying Tokamak Edge Physics Using Modern Computational Tools”. Dr. Chang described the organization and objectives of the Center for Plasma Edge Simulation (a SciDAC prototype-FSP center), as well as providing an overview of recent work done by the project. Dr. Ku presented turbulence simulations done with the gyrokinetic particle code XGC1, one of the main CPES codes.
December 3, 2010
THEORY GROUP
Prof. Riccardo Betti was awarded the Fusion Power Associates Leadership Award at the FPA meeting in Washington DC on December 1-2 2010. In selecting Dr. Betti, the FPA Board recognizes "the leadership he has been providing to the U.S. and world inertial fusion efforts, including his contributions to the search for efficient methods of igniting fusion targets, contributions to the emerging field of high energy density physics, and his advisory role in the DOE's Fusion Energy Sciences Advisory Committee". At the FPA meeting, Prof. Betti gave a talk on "ignition options for laser inertial fusion."The paper "A synthetic diagnostic for validation of electron gyroradius scale turbulence simulations against coherent scattering measurements," by F.M. Poli, S. Ethier, W. Wang, TS. Hahm, E. Mazzucato, D.R. Smith has been published in Physics of Plasmas (Vol.17, Issue 11). The paper focusses on the development of a synthetic diagnostic for validation of ETG simulations against the measurement of small scale density fluctuations. The synthetic diagnostic is based on the high-k scattering system installed on NSTX and the code has been tested on the global, nonlinear gyrokinetic code GTS.
Dr. Nathaniel Ferraro from General Atomics gave a theory seminar entitled, "Non-axisymmetric Response and Stability Calculations Using a Non-Ideal Two-Fluid Model" on Nov. 29, 2010.
In the talk, he presented that a comprehensive extended-MHD model was applied to two important and related tokamak phenomena: the calculation of edge-localized mode (ELM) stability, and the plasma response to non- axisymmetric external fields. He also showed the effect on these phenomena of including resistivity, rotation, and two-fluid effects. These calculations were carried out using the initial-value finite- element code M3D-C1.
Response to "Comment on 'Nonlinear gyrokinetic theory with polarization drift''' [Phys. Plasmas 17, 124701 (2010)] authored by Lu Wang (WCI, NFRI, Korea) and T.S. Hahm has been published in December issue of Phys. Plasmas.
In this response, the relation between Wang and Hahm [Phys. Plasmas 17, 082304 (2010)] and Sosenko et al., [Phys. Scr. 64, 264 (2001)] has been further clarified.
Allan Reiman and John Krommes gave a joint Theory Department Seminar on "Calculation of Equilibria with Nonzero Pressure Gradients in Stochastic Regions". The magnetic differential equation determining the component of the pressure-driven current parallel to the magnetic field is cast in the same form as standard equations of turbulence theory. This allows the application of mathematical methods of turbulence theory, in particular resonance-broadening. There is a causality issue that arises, and this is handled by working in terms of causal and anti-causal Green’s functions. There is also a periodicity issue, and this is handled by using the ballooning representation. The resulting model has been incorporated in the PIES code, and has been applied to the calculation of reconstructed W7AS equilibria. It is found that as the plasma pressure is increased in W7AS equilibria, there is a threshold in beta above which a stochastic region appears at the plasma edge, and that the width of the stochastic region increases as beta is increased. Calculated differences between the equilibrium solutions in the width of the stochastic regions and in the field line diffusion coefficient provide a plausible explanation for previously puzzling observations on W7AS. The calculated equilibrium solutions are consistent with the available experimental data.
CPPG GROUP D. McCune and S. Jardin attended the three day EU-US Workshop on Software Technologies for Integrated Modeling in Gothenburg, Sweden. From the US, the SWIM, FACETS, CPES, and CEMM projects were represented. From Europe, the EUFORIA (EU Fusion fOR Iter Application) project was described. This is a European Union project that developed a comprehensive framework and infrastructure for core and edge transport and turbulence simulation, linking grid and HPC to the fusion modeling community. Also represented was ITM, the EFDA Integrated Tokamak Modeling task force. Extensive discussions were held regarding identifying areas where EU/US collaboration would be jointly beneficial. A Whitepaper summarizing discussions is being produced.
November 19, 2010
THEORY GROUP It was announced that the PPPL-led a five-year proposal entitled, "Center for Nonlinear Simulation of Energetic Particles in Burning Plasmas (CSEP)”, has been recommended for funding under DOE Program LAB10-316 "Scientific Discovery through Advanced Computing: Advanced Simulation of Fusion Plasmas". The proposed center consists of collaborators from PPPL, the Institute for Fusion Studies, the University of Colorado, and ORNL. The objective of the center is the predictive simulation of energetic particle-driven instabilities and energetic particle transport in present tokamak devices and future burning plasma experiments.Gianluca Spizzo from CNR - Instituto Gas Ionizzati in Italy is visiting the Theory Department for two weeks to continue work in the areas of turbulent transport in reversed-field pinches with Roscoe White and others in the Theory Department.
On November 18, Dr. Tomo-Hiko Watanabe from NIFS, Japan, gave a theory seminar entitled “Gyrokinetic simulation on ITG turbulence and zonal flows in helical configurations”. In his talk, he showed that the zonal flow response in non-axisymmetric configurations (Large Helical Device (LHD)) is increased by optimizing magnetic field structures or by imposing an equilibrium-scale radial electric field. The enhanced zonal flow generation leads to the ITG turbulence suppression and transport reduction, which is regarded as coupling of the neoclassical and anomalous transport processes in non-axisymmetric systems.
The Edge Coordinating Committee (Daren Stotler, Chair) and the FY2011 Joint Research Target Working Group (Rich Hawryluk, Chair) hosted a lunch time meeting on the FY2011 Joint Experimental – Theoretical Research Target in conjunction with the APS-DPP meeting in Chicago. The agenda included an overview of the milestone by Hawryluk and presentations from four modeling groups. COMPUTATIONAL PLASMA PHYSICS GROUP
Stephane Ethier attended the SC10 International Conference for High Performance Computing, Networking, Storage, and Analysis in New Orleans, LA. One focus of the SC technical program this year was programming models for heterogeneous systems, essentially CPU + GPGPU systems, which are becoming even more prevalent.
November 5 & 12, 2010
Theory Group
Weixing Wang attended the Meeting of International Advisory Committee & Scientific Program Committee of Center for Magnetic Fusion Theory, Chinese Academy of Sciences in Hefei, China on October 18-19, and gave a talk on “Turbulence Driven Intrinsic Rotation in Tokamaks -- What We Have Learned From Global Gyrokinetic Simulations”. He also attended the International Workshop on Fusion Theory and Simulation at the Fusion Simulation Center of Peking University, China on October 20-22, and gave a talk on “Gyrokinetic Turbulence Driven Plasma Transport in Multiple Channels and Comparison with Experiments”.
On October 18-20, Leonid Zakharov attended the MHD ITPA meeting discussing the use of gas injection for mitigation runaway electron production. On October 20-31, he visited HUST (Wuhan) and ASIPP (Hefei) China. Leonid participated in discussion of measurements and setup of dedicated experiments on disruptions in J-TEXT. In ASIPP he gave a talk with assessment of MHD effects on different design options for the flowing lithium system for T-7 tokamak.
Dr. K. Avinash from Centre for Space Plasma and Aeronomic Research University of Alabama gave a Theory Seminar titled “Stirling like engine and heat pump using plasma electric fields.”
Researchers from the Theory department attended and participated the Annual Meeting of the APS Division of Plasma Physics, November 8-12 in Chicago, IL. The Theory group had five invited talks; Numerical Modeling of NBI-driven sub-cyclotron frequency modes in NSTX” by Elena Belova,“ Nonlinear Simulation of Energetic Particle-driven Alfv\'en Instability with Source and Sink <http://meetings.aps.org/Meeting/DPP10/Event/131374> ” by Jianying Lang, “Minimizing stellarator turbulent transport by geometric optimization” by Harry Mynick, “Generalized Courant-Snyder theory and Kapchinskij-Vladimirskij distribution for high intensity beams in coupled transverse focusing lattices” by Hong Qin and “Novel Hamiltonian method for collective dynamics analysis of an intense charged particle beam propagating through a periodic focusing quadrupole lattice” by Edward Startsev.
W. W. Lee presented an invited talk, entitled "Recent Controversy and Progress in Global Gyrokinetic PIC Simulation" at 2010 US-Japan Workshop on the "Development of Simulation Science in Plasma Physics" after the annual APS meeting in Chicago.
CPPG Group
It was announced this week that the PPPL-led five-year proposal entitled, "Center for Extended Magnetohydrodynamic Modeling (CEMM)" has been recommended for funding under DOE Program LAB10-316 "Scientific Discovery through Advanced Computing: Advanced Simulation of Fusion Plasmas". The 12-institution Center will receive $1,050,000/year, beginning in FY11. The proposed work aims at further developing the world's most powerful simulation codes for studying the macroscopic dynamics of MHD-like phenomena in fusion plasmas, and using them on the most advanced computers to address critical issues facing burning plasma experiments such as ITER.
The latest version of TORIC, with the correction to ICRF current drive recently completed by Dr. John Wright at MIT, is now available in the "tshare" production version of TRANSP/PTRANSP.
Stephane Ethier gave a presentation at Princeton University as part of the "Lunch'n Learn" information technology seminar series (http://www.princeton.edu/academicservices/about/director/lunch-n-learn/).
The title of his talk was "Optimizing Fusion Particle Codes for Massively Parallel Computers".
October 22, 2010
THEORY GROUPA. Reiman presented a poster at the IAEA meeting in Daejeon, Korea, on “Equilibria with Nonzero Pressure Gradient in Stochastic Regions”.
Riccardo Betti presented two invited talks at the 4International Conference on Superstrong Fields in Plasmas held at Villa Monastero, Varenna (Italy), October 3-9. The talks described the National Ignition Campaign and the figures of merits used to assess progress towards the demonstration of thermonuclear ignition. The titles of the talks were: "The Lawson criterion for inertial confinement fusion" and "The path to ignition within the US inertial confinement fusion program."
Josh Breslau presented a poster on, "Onset and Saturation of a Non-Resonant Internal Mode in NSTX and Implications for AT Modes in ITER" with seven PPPL co-authors at the IAEA Fusion Energy Conference in Daejeon, South Korea.
Jay Johnson attended the Theory of the Magnetosphere meeting in Santa Fe, NM, Oct 4-8 and presented an invited talk addressing the role of heavy ions on plasma entry and transport processes in the magnetosphere.
Peter Damiano presented a talk at the Laboratory for Atmospheric and Space Physics on Oct 13 about the role of dispersive effects on electron energization and Alfven wave dissipation in the auroral region.
COMPUTATIONAL PLASMA PHYSICS GROUP
Prof. Daniel Reynolds, from Southern Methodist University, gave a CPPG seminar: "Toward Scalable Implicit Solvers for Resistive MHD". He discussed an effort to construct scalable solvers for resistive MHD using fully implicit time discretizations using preconditioned
Newton-Krylov techniques. Prof. Reynolds stayed for discussions on how to implement some of these same techniques in the M3D-C1 code.
Stephane Ethier attended the IAEA FEC conference in Daejeon, Korea, where he presented a poster on "Global Gyrokinetic Simulation of Electron Temperature Gradient Turbulence and Transport in NSTX Plasmas".
October 8, 2010
THEORY GROUPRoscoe White is hosting Dr. Yaroslav Kolesnychenko and Dr. Yuriy Yakovenko from The Institute for Nuclear Research Kyiv, Ukraine. They are visiting PPPL for a one month; the work subject to this visit will include interaction on high energy particles with MHD in NSTX. It will also entail discussions with others at the laboratory for future collaborations regarding NSTX.
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Jardin attended the kickoff meeting of the CERF Center: Co-Design for Exascale Research in Fusion. This is five-year project involving fusion scientists and computational scientists from seven institutions that is being funded by a recent initiative from the Office of Advanced Scientific Computing Research. It is one of five such centers that were recently created by DOE under the proposal call LAB10-07.
October 1, 2010
THEORY GROUPSamuel Lazerson attended a MATLAB Seminar entitled "Speeding Up Applications: Parallel Computing with MATLAB" on Princeton University’s main campus.
A paper titled, “On Nonlinear Self-interaction of Geodesic Acoustic Mode driven by Energetic Particles “ by Guo-Yong Fu has recently been accepted for publication in Journal of Plasma Physics. The abstract reads: It is shown that nonlinear self-interaction of energetic particle-driven Geodesic Acoustic Mode does not generate a second harmonic in radial electric field using the fluid model. However, kinetic effects of energetic particles can induce a second harmonic in the radial electric field. A formula for the second order plasma density perturbation is derived. It is shown that a second harmonic of plasma density perturbation is generated by the convective nonlinearity of both thermal plasma and energetic particles. Near the mid-plane of a tokamak, the second order plasma density perturbation is negative on the low field side with its size comparable to the main harmonic at low fluctuation level. These analytic predictions are consistent with the recent experimental observation in DIII-D.
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Jardin presented a lecture in the Colloquium Series on Computational and Applied Mathematics at Penn State University titled, "An efficient high-order implicit algorithm for 3D magnetohydrodynamic studies of strongly magnetized plasmas using C1 finite elements."
Preliminary TRANSP production figures are available for FY-2010. The total number of runs was 6960, a 35% increase over FY-2009. There were also 164 MPI runs, nearly three times the FY-2009 number. In descending order by tokamak, NSTX had 1775 runs, Asdex-U 1644 runs, DIII-D 932 runs, MAST 852 runs, EAST 548 runs, C-Mod 357 runs, MST 291 runs, JET 111 runs, and HL2A 65 runs. There were also 385 PTRANSP predictive runs for ITER.
September 24, 2010
THEORY GROUPOn September 21-22, a DOE appointed panel, chaired by Dr. Curt Bolton, reviewed the PPPL Department of Theory and Computation. The two-day review featured a series of presentations by Theory Department researchers highlighting the progress made in the last five years and the plans for the future. The presentations to the DOE panel covered a wide range of research activities in fusion plasma theory spanning from turbulent transport to macroscopic stability and from energetic particle physics to plasma-material interactions. During the second day of the review, a series of talks described the close connections between theorists and experimentalists at PPPL
Weixing Wang attended the EFDA Transport Topical Group Meeting combined with EU-US Transport Task Force Meeting in Cordoba, Spain, and presented a talk on “Electron Turbulence Driven Non-diffusive Momentum Transport and Intrinsic Rotation”.
September 17, 2010
THEORY
Ernest Valeo attended the RF SciDAC summer workshop (at PPPL, Sept 14-16). He presented a talk on work done in collaboration with Jay Johnson, Eun-Hwa Kim and Cynthia Phillips entitled, “Two Dimensional Finite Element Wave Code – status and plans.”
September 10, 2010
THEORY
Allan Reiman gave an invited talk, “3D Equilibria with Stochastic Regions Supporting Finite Pressure Gradients” and Weixing Wang also gave an invited talk, “What We Have Learned About Intrinsic Rotation From Global Gyrokinetic Simulations” at the meeting, “The Theory of Fusion Plasmas” in Varenna, Italy.
September 3, 2010
COMPUTATIONAL PLASMA PHYSICS GROUP
Dr. Scott Klasky of Oak Ridge National Lab (ORNL) gave a CPPG seminar titled, "Adios 1.2: Preparing for the Xscale". He discussed the importance of increasing the performance of Input/Output (I/O) operations in achieving Exa scale computing objectives and the contribution of the ADIOS software suite toward that end.
K. Indireshkumar (Kumar) visited the MIT Plasma Fusion Center to discuss with MIT physicists the use of the GENRAY and CQL3D codes in modeling Lower Hybrid (LH) heating/current drive in Alcator C-Mod. The goal of the visit was to facilitate integration of these codes into TRANSP to enable time-dependent analysis of LH in C-Mod and other tokamaks. He worked with G. Wallace, P. Bonoli, A. Schmidt, A Hubbard, C. Fiore and J. R. Wilson.
S. Jardin participated in the Proto-FSP assessment activity organized by Walter Polansky and John Mandrekas. He presented a talk on "Physics Studies using the SWIM Framework" as part of the presentation representing the Center for Simulation of Wave Interactions with MHD
August 27, 2010
THEORY GROUP
Daren Stotler presented an invited talk titled "Molecules in Fusion Plasma Diagnostics and Fueling" at the International Conference on Dissociative Recombination", August 16-20, in Lake Tahoe, California. The talk first described the role of molecules in the Gas Puff Imaging
plasma turbulence diagnostic developed by Stewart Zweben and Ricardo Maqueda and used on NSTX, Alcator C-Mod, and numerous other devices. Second, the development and testing of a Molecular Cluster Injector being built by graduate student Daniel Lundberg for deployment on LTX was discussed.
COMPUTATIONAL PLASMA PHYSICS GROUP
Stephane Ethier served on the NERSC Operational Assessment Review committee. The DOE-required review took place on August 26-27 at the NERSC Oakland Supercomputer Facility (OSF) in Oakland, CA.
Prof. Jincheol Kim and his student, Minwoo Kim, from POSTECH (Pohang, Korea, Univ. of Science and Technology) have completed their four week visit to learn PPPL's reflectometer simulation code. Using the web service interface, they ran about 100 simulation cases that encapsulated a total of 6000 runs. They will be using the code to design a new imaging reflectometer diagnostic for KSTAR. Training and technical support was provided by Ernie Valeo, Gerrit Kramer, and Eliot Feibush.
August 20, 2010
THEORY GROUP
An article by Lu Wang (a former visiting student from Peking University) and T.S. Hahm, entitled, "Nonlinear gyrokinetic theory with polarization drift," has been published online on August 16, in Physics of Plasmas (Vol.17, Issue 8). In this work, a set of equations comprising the electrostatic toroidal gyrokinetic Vlasov equation and the Poisson equation, which explicitly includes the polarization drift, is derived systematically by using Lie-transform perturbation method. Surprisingly, the inclusion of the polarization drift in the gyrocenter equation of motion does not affect the expression for the polarization density significantly. This is due to modifications of the gyrocenter phase-space volume caused by the electrostatic potential [T.S. Hahm, Phys. Plasmas 3, 4658 (1996)].
COMPUTATIONAL PLASMA PHYSICS GROUP
K. Indireshkumar (Kumar) attended the semi-annual FACETS All Hands meeting at Tech-X in Boulder, Colorado. He participated in discussions on FACETS, Proto-FSP reviews and PPPL contribution to FACETS. He also collaborated with Tech-X researchers on building the FACETS software on PPPL machines. As a result, FACETS has been built for the first time on the PPPL Portalr5 (Stix) machines.
August 13, 2010
Theory GroupRiccardo Betti chaired a three-day meeting on Electron Divergence in Fast Ignition at Lawrence Livermore National Laboratory. About 60 attendees participated at this meeting. The goal of the meeting was to review all the available data on the electron angular divergence in fast ignition and to identify a path forward. In addition to R. Betti's group and collaborators from OSU, UCLA, UCSD, LLNL, MIT, UNR, scientists from Imperial College, Rutherford Laboratory and Osaka University attended this meeting.
-The paper "Optimizing stellarators for turbulent transport", by Drs. Harry Mynick (PPPL), N. Pomphrey (PPPL), and P. Xanthopoulos (IPP-Greifswald) has been accepted for publication Physical Review Letters.
Abstract:
Up to now, the term ``transport-optimized'' stellarators has meant optimized to minimize neoclassical transport, while the task of also mitigating turbulent transport, usually the dominant transport channel in such designs, has not been addressed, due to the complexity of plasma turbulence in stellarators. Here, we demonstrate that stellarators can also be designed to mitigate their turbulent transport, by making use of two powerful numerical tools not available until recently, namely gyrokinetic codes valid for 3D nonlinear simulations, and stellarator optimization codes. Two initial proof-of-principle configurations are obtained, reducing the level of ion temperature gradient turbulent transport from the NCSX baseline design by a factor of 2--2.5
Profs. Greg Hammett and John Krommes are participating in a 4 week research program at the Isaac Newton Institute at Cambridge University on "Gyrokinetics in Laboratory and Astrophysical Plasmas", organized by Schekochihin, Dorland, and Nazarenko, http://www-thphys.physics.ox.ac.uk/research/plasma/ukgk.html
Topics being investigated include gyrokinetic phase-space turbulence, internal transport barriers, kinetic reconnection, edge plasma turbulence, microtearing, gyrokinetics for simple laboratory plasma configurations, applications in space and astrophysical plasmas, and approaches to global full-f gyrokinetic simulations.
Dr. A. Reiman visited General Atomics from August 2 to August 6. He gave a seminar on “Stabilization of the Vertical Mode in Tokamaks by Localized Nonaxisymmetric Fields”, and he engaged in discussions of the effects of nonaxisymmetric fields in tokamaks.
A new version of parallel TORIC, with an improved performance solver from MIT, has been demonstrated to run time dependently at moderately high spatial resolution in TRANSP for the first time. Using a 96 processor block with Infiniband interconnect, a speedup factor of about 23.5 was achieved. This enabled an earlier JET simulation with a 5 second ICRF heating pulse, that had ran for one month as a serial job, to be completed in 30 hours. Possibilities for production deployment of this new capability are being investigated.
S. Jardin delivered 6 hours of lectures to over 90 participants on "MHD simulations for fusion applications" at the CEMRACS 10 scientific event of the French Society of Applied and Industrial Mathematics. The event this year was devoted to Numerical Modeling of Fusion Plasmas. It was held at the Centre International de Recontres Mathematiques in Marseille. CEMRACS stands for Centre d'Ete Mathematique de Recherche Avancee en Calcul Scientifique. The lecture notes will be published in a collection of the French Mathematical Society.
The CPPG Display Wall upgrade continued by replacing the plastic screen with a translucent vinyl screen. The fabric screen is stretched under tension to provide a planar projection surface. This produces a more sharply focused image than on the plastic screen that had developed curvature. The new screen transmits 75% of the light emitted from the projector compared to 40% by the plastic screen. Color fidelity and color contrast are improved along with increased brightness.
August 6, 2010
THEORY GROUPThe paper entitled, "Nonlinear flow generation by electrostatic turbulence in tokamaks" by W. X. Wang, P. H. Diamond (University of California, San Diego), T. S. Hahm, S. Ethier, G. Rewoldt
and W. M. Tang, has been published in Physics of Plasmas (Vol.17, Issue 7, http://link.aip.org/link/?PHP/17/072511). The paper describes recent new results of turbulence driven intrinsic rotation obtained from
global gyrokinetic simulations. In particular global gyrokinetic simulations have revealed an important nonlinear flow generation process due to the residual stress produced by electrostatic
turbulence of ion temperature gradient (ITG) modes and trapped electron modes (TEMs). In collisionless TEM (CTEM) turbulence, nonlinear residual stress generation by both the
fluctuation intensity and the intensity gradient in the presence of broken symmetry in the parallel wavenumber spectrum is identified for the first time. Concerning the origin of the symmetry
breaking, turbulence self-generated low frequency zonal flow shear has been identified to be a key, universal mechanism in various turbulence regimes. Simulations reported here also indicate
the existence of other mechanisms beyond EXB shear. The ITG turbulence driven "intrinsic"
torque associated with residual stress is shown to increase close to linearly with the ion
temperature gradient, in qualitative agreement with experimental observations in various devices. In CTEM dominated regimes, a net toroidal rotation is driven in the cocurrent direction by
intrinsic torque, consistent with the experimental trend of observed intrinsic rotation. The finding
of a "flow pinch" in CTEM turbulence may offer an interesting new insight into the underlying
dynamics governing the radial penetration of modulated flows in perturbation experiments. Finally, simulations also reveal highly distinct phase space structures between CTEM and ITG
turbulence driven momentum, energy, and particle fluxes, elucidating the roles of resonant and non-resonant particles. Weixing Wang attended the SciDAC (Scientific Discovery through Advanced Computing) 2010
Conference which was held July 11-15 in Chattanooga, Tennessee, where he gave an invited talk
on the topic of "Non-Diffusive Momentum Transport and Intrinsic Rotation in Tokamaks".
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Ethier, S. Jardin, and D. McCune attended the two-day invitation-only workshop entitled"Large Scale Production Computing Requirements for Fusion Energy Sciences" which was
sponsored jointly by OFES and ASCR. The workshop's goal was to characterize FES production
computing requirements over the next three to five years at NERSC, the National Energy
Research Scientific Computing Center. They participated in developing and presenting "case
studies" in the areas of MHD, Plasma Turbulence & Transport, and the Fusion Simulation
Program. These case studies will be used with others from OFES and other offices within the
DOE Office of Science (SC) to define the requirements for the next generation of computers at
NERSC.
Stephane Ethier attended the SciApps-10 workshop organized by the National Center for
Computational Science (NCCS) and taking place at the Oak Ridge National Laboratory. This
workshop brings together an interdisciplinary team of computational scientists to share
experience, knowledge, and best practices on the implementation of a wide range of
scientifically demanding and computationally paced applications on leading-edge highperformance
scientific computer systems. Dr. Ethier gave a presentation entitled:
"Scaling Global Gyrokinetic PIC Codes to Petascale and Beyond".
July 30, 2010
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Jardin attended a meeting of the international group addressing the ITER task "Update of TSC
code and Simulations of ITER disruptions/VDEs scenarios" at the ITER Cadarache site. The
weeklong meeting consisted of detailed reports from all the participants on TSC and DINA
disruption modeling calculations for ITER, and comparison with each other and with
experimental data from ASDEX-U and NSTX. Dr. Jardin was also asked to give a general
seminar to the ITER staff on "2D and 3D MHD simulation of tokamaks: status and plans".
July 16, 2010
THEORY GROUP
A PPPL-led proposal, "Co-Design Center for Exascale Simulations of Fusion Plasmas," has been submitted to the Office of Advanced Scientific Computing Research (ASCR) in response to its program announcement to DOE national laboratories on June 8, 2010. W. W. Lee is the PI of the proposed center, which consisted of five national laboratories, five universities and one industrial research center. The proposal is based on the use of gyrokinetic Particle-In-Cell approach to achieve exascale computing with an integrated team of scientific researchers, applied mathematicians, computer scientists and computer architects. Other PPPL participants of the proposal are: S. Ethier, R. Samtaney and E. A. Startsev.
COMPUTATIONAL PLASMA PHYSICS GROUP
PPPL CPPG staff member Marina Gorelenkova visited Auburn University to take the ADAS course. This training provided an intensive introduction to the ADAS atomic physics codes and database. ADAS is a resource for use in fusion diagnostic applications, such as excited population and spectral emissivity modeling, ionization balance modeling, charge exchange modeling, generalized collisional radiative modeling, and generation of atomic data tables for use in simulations. PPPL joined the ADAS consortium and acquired access to ADAS software in 2009.
Stephane Ethier attended the SciDAC 2010 Conference in Chattanooga, TN. He was on the organizing committee for the conference and chaired the session highlighting the latest SciDAC-related work in fusion energy science.
A major verification and validation exercise in the Free-Boundary PTRANSP development program was completed this week. A free boundary TSC run was made of the current ramp-up and flattop phases of a NSTX discharge using the experimental values of the coils currents, but with the axisymmetric passive conductors removed. We used this data to drive a time series of free-boundary PTRANSP equilibrium calculations of the same discharge, using the same coil currents and the TSC values of the pressure and q-profiles. Excellent agreement between the two code calculations was obtained for the fluxes at the flux loop locations and for the plasma shape parameters. Work on including the passive conductors in the PTRANSP circuit equations is now underway.
July 2, 2010
COMPUTATIONAL PLASMA PHYSICS GROUP
Doug McCune visited General Atomics for TRANSP/PTRANSP collaboration. MPI-enabled development copies of TRANSP were successfully built on GA Computational clusters, and there was technical progress establishing connections between TRANSP/PTRANSP and GA's GCNMP stiff transport model integrator, their IMFIT simulations framework, and kinetic EFIT analysis. A PTRANSP feature was modified to enable extraction of (SWIM SciDAC) Plasma State pairs as NetCDF files for GCNMP testing. Also, recent progress and current code development efforts were reviewed at a well attended TRANSP Users' Group meeting with video participation from ORNL and MIT.
A new version of ElVis was released that contains a web service for the PEST code. The user enters a shot number and receives a list of available EFIT times. Then the user chooses one or more EFIT times to be the input for running PEST. The textual output is printed in a status panel. The output data is visualized in graphs of the cosine terms, sine terms, and eigenvector plot. The sine and cosine curves are plotted with a color gradient to reinforce the order of the curves. The eigenvector plot is automatically scaled so the cross section is displayed with the correct aspect ratio.
June 25, 2010
THEORY GROUPDr. Bruce Scott from Max-Planck-IPP EURATOM Association gave a seminar entitled, "Gyrokinetic Edge Turbulence" on June 24. In this talk, Dr. Scott reviewed a generalized flux tube delta-f gyrokinetic model used to compute edge turbulence. Using this model, full flux-surface edge turbulence results with realistic scale separation were obtained for the first time. His simulations showed that instabilities occur at the scale of circa ten ion gyroradii, while nonlinear redistribution fills the spectrum. Transport scaling of the edge turbulence is determined more by saturation through the strong nonlinearity than the linear drive.
A paper entitled “Centroid and Envelope Dynamics of High-Intensity Charged-Particle Beams in an External Focusing Lattice and Oscillating Wobbler” by Hong Qin, Ronald C. Davidson, and B. Grant Logan has been published in Physical Review Letters (http://prl.aps.org/abstract/PRL/v104/i25/e254801). In this paper, the centroid and envelope dynamics of a high-intensity charged-particle beam are investigated as a beam smoothing technique to achieve uniform illumination of the target for applications to ion-beam-driven high energy density physics and heavy ion fusion. The basic idea is to induce an oscillatory motion of the centroid for each transverse slice of the beam such that the centroids of different slices strike different locations on the target. The motion of the centroid projected onto the target is designed to follow a smooth pattern in order to achieve the desired uniform illumination over a suitably chosen region, e.g., an annular region, for significantly improved stability properties during the target implosion phase. The centroid dynamics is actively controlled by the deflection force imposed by a set of biased electrical plates, which are called ‘‘wobblers,’’ because of the wobbling motion that they induce in the beam centroid motion. The bias voltage on the wobbler plates oscillates with time in order to deliver different beam slices to different locations on the target. In laser-driven inertial confinement fusion research, uniformity of laser illumination is also critically important, and sophisticated smoothing systems using distributed phase-plate technology have been developed. The wobbler system for high intensity beams described here is analogous to these smoothing systems for laser beams.
Dr. David Coster (Max Planck Institute for Plasma Physics, Garching, Germany) visited PPPL June 21-25. On June 21, he led an informal discussion on the European Integrated Tokamak Modeling effort to PPPL participants in the Fusion Simulation Program Planning project. On June 23, Dr. Coster gave a talk on his edge and scrape-off layer plasma transport work to the Boundary Physics Science Focus Group. Multiple individual discussions on those topics and others also took place during his stay.
Keshavamurthy Indireshkumar and Stephane Ethier attended the DOE Computational Science Graduate Fellowship (DOE CSGF) program annual conference in Washington, DC. This program provides outstanding benefits and opportunities to students pursuing a PhD in scientific or engineering disciplines with an emphasis in high-performance computing. Students are required to complete a practicum (research assignment) at a DOE research laboratory for a twelve-week period. The practicum is intended to broaden the fellows’ experience outside the main thesis path and to make them become better aware of the areas that define computational science. PPPL has been actively participating in this program since its inception and continues to attract students for their practicum.
June 18, 2010
THEORY GROUP
On June 17, Leonid E. Zakharov gave a presentation on "Potential burning plasma regimes in ST based neutron sources" to the Workshop on Volumetric Neutron Source (Zvenigorod, Russia).
Dr. Bruce Scott from Max-Planck-IPP EURATOM Association gave a seminar entitled, "Momentum conservation in total-f gyrokinetics" on June 17. In the talk, Dr. Scott briefly reviewed the modern theory of gyrokinetics. He recapped the energy discussion and then focused on the demonstration of momentum conservation. He showed that the phase space integral of the toroidal canonical momentum is conserved demonstrating that long-wavelength modern gyrokinetics is adequate to describe flows driven by neoclassical effects and/or turbulence.
COMPUTATIONAL PLASMA PHYSICS GROUP
Robert Preissl completed a four-week visit at PPPL to work on a close collaboration with Stephane Ethier and Weixing Wang. Dr. Preissl, a post-doctoral fellow at LBL/NERSC, is working on maximizing the performance and scalability of the global Gyrokinetic Tokamak Simulation code (GTS) for the upcoming Hopper system upgrade at NERSC, which will have the latest Cray XE6 technology with over 150,000 cores and a new interconnect.
S. Jardin presented an invited talk "An efficient high-order implicit algorithm for 3D MHD studies of strongly magnetized plasmas using C1 finite elements" at the Fifth European Conference on Computational Fluid Dynamics in Lisbon, Portugal. This conference was sponsored by the European Community on Computational Methods in Applied Science. The talk was in a special session on "Implicit solution methods for MHD systems". J. Breslau, J. Chen, and N. Ferraro (General Atomics) were co-authors.
June 11, 2010
THEORY GROUP
A special Issue of Nuclear Fusion containing eighteen papers presented at the International Workshop on H-mode Physics and Transport Barriers has appeared online in the June 2010 issue. This workshop was held at PPPL September 30-October 2, 2009. T.S. Hahm served as the Chair of the International Advisory Committee which decided topics and scientific program. The special issue includes the following papers from the Theory Department and the NSTX team: "Transport of parallel momentum by toroidal ion temperature gradient instability near marginality" by E.S. Yoon and T.S. Hahm, "Overview of L-H power threshold studies in NSTX" by R. Maingi et al., "First observation of ELM pacing with vertical jogs in a spherical torus" by S.P. Gerhardt et al., and "Progress in the development of ELM pace-making withnon-axisymmetric magnetic perturbations in NSTX" by J.M. Canik et al.
Prof. John Krommes was a principal lecturer at the Summer School on Self-Organization in Turbulent Plasmas and Fluids, held May 3-7 at the Max Planck Institute for the Physics of Complex Systems, Dresden, Germany. He presented five hours of lectures on the general theme of "Plasma Turbulence." At the accompanying Workshop on Self-Organization that was held the following week, he also presented an invited talk on the topic "Zonal-flow generation in turbulent magnetized plasmas, and its relation to eddy viscosity in 2D turbulent fluids."
On June 7-8, Leonid E. Zakharov visited Institute of Fusion Studies (UT at Austin) for discussion of disruption theory and simulations addressing the ITER needs. He gave a seminar talk on "Disruptions - a New Look at the Old Tokamak Problem". He explained that although phenomenology of disruptions is now well established, very little were really understood in their physics, which typically was related to the messy dynamics coming out of numerical simulations. Initial shift in understanding of disruptions was made in 2007 when the long standing interpretation of currents in the wall as the "halo" currents has been ruled out and replaced by the theory of the wall touching kink mode. The talk emphasized the necessity of new developments in plasma edge, plasma-wall interaction physics, and energetic particle kinetics, as well as needs in transition from the present, essentially hydro-dynamic, numerical approaches to the new ones, which would be consistent with the high plasma anisotropy.
COMPUTATIONAL PLASMA PHYSICS GROUP (D. MCCUNE/S. JARDIN):
A major development milestone for the Tokamak Simulation Code (TSC) has been met this week and committed to the SVN code repository. We now have the capability of importing density and/or temperature profiles from the experimental database when performing a free-boundary TSC simulation of an existing experimental discharge. The new capability makes use of the existing TRXPL and Plasma State software. When TSC requests a profile at a given time, two Plasma State files at times which bracket the requested time are fetched from the MDS+ TRANSP archive, and are interpolated to provide the profile at the TSC requested time. The new capability is activated by setting acoef(4991)-(4993) in the standard TSC input file. The name of the experiment, shot number, and TRANSP runid are input in the execution command line. This capability is available either when running TSC stand-alone or as a SWIM component. For additional information, and help in setting up and interpreting a run, please contact Jin Chen at jchen@pppl.gov.
June 4, 2010
THEORY GROUP
Daren Stotler attended the ARIES Town Meeting on "Edge Plasma Physics and Plasma Material Interactions in the Fusion Power Plant Regime", May 20-21 in San Diego, and gave a talk entitled, "Neutral Transport from Wall to Scrape-Off Layer". His presentation, as well as most of the other talks from the meeting, can be found at: http://cer.ucsd.edu/ATMPMI2010/program.shtml
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Jardin presented an invited lecture at the Fourth ITER International Summer School (ISS2010), which was held at the University of Texas at Austin. The school thematic this year was, "Magnetohydrodynamics and Plasma Control in Magnetic Fusion Devices". His lecture was an overview on "Predictive simulation of global instabilities in tokamaks". The ISS2010 was attended by over 130 scientists and students from around the world.
May 28, 2010
THEORY GROUP
Dr. Peter Damiano form Thayer School of Engineering, Dartmouth College, gave a seminar entitled " Hybrid MHD-kinetic electron simulations of a standing shear Alfven wave " on May 27. In his presentation he highlighted simulation results of the Field Line Resonances (FLR) system for a variety of resonance widths and electron temperatures. He showed that the acceleration of the electrons can be a significant sink of Alfven wave energy and that the parallel electric field needed to sustain a given parallel current must increase with electron temperature due to mirror force effects. The accelerated electron populations form ring distributions in velocity space, the radius of which increases with electron temperature. As time progresses, the ability of the system to accelerate electrons along the original flux tube becomes impeded because of a lack of accessible current carriers and electrons are accelerated along adjacent field lines to compensate. This broadening of the original current profile may be facilitated by the development of small perpendicular scale length fluctuations within the simulation
COMPUTATIONAL PLASMA PHYSICS GROUP
Dr. Teck Lee from Auburn University presented a CPPG seminar on "Computational Aspects of Atomic Data for Fusion Plasma Modeling". He discussed first principle calculations of charge exchange and electron impact ionization using Schrodinger's equation. These calculations, along with experimental measurements where possible, are used to provide cross-section data for the ADAS data base, which in turn are widely used in fusion simulations
May 21, 2010
THEORY GROUP
On May 19, Leonid Zakharov gave a talk to the International Conference on Nuclear Engineering on "Fission-Fusion Research Facility (FFRF) As a Practical Step toward Hybrids". FFRF and its plasma regime can serve as a reference point for the next step proposal for the Chinese fusion program. He outlined the potential difference in design strategy between ITER and FFRF, where the development of innovative plasma regimes will be done in parallel with designing the machine. Both fusion and fusion-fission missions of FFRF have been explained.
Prof. Fedor S. Zaitsev from Moscow State University, Moscow, Russia gave a seminar entitled, "Analyses of substantially different plasma current densities and safety factors reconstructed from magnetic diagnostics data" on May 20. He pointed out that in the traditional formulation, the problem of plasma current density and safety factor reconstruction using magnetic field measurements is strongly ill-posed. In particular, substantially different current densities and safety factors can be equally well attributed to the same set of measurements. In the talk, he presented an accurate mathematical formulation of the inverse problem and its variants. He gave the idea of a numerical algorithm, which allows to find all substantially different solutions or to prove the absence of multiple solutions. He presented examples of very different current density and safety factor reconstructions for measurements with finite accuracy, including cases of MAST, JET and ITER-like plasmas. He showed that including the Motional Stark Effect (MSE) measurements as constraints, provided the accuracy of MSE measurements is sufficient, allows identifying one solution.
Dr. Yakov S. Dimant from Boston University gave a seminar entitled, "Plasma Instabilities in the Lower Earth’s Ionosphere and Their Macroscopic Effects" on May 21. In the talk, he reviewed the E/D-region instabilities and related macroscopic processes, such as the formation of nonlinear currents and strong anomalous electron heating which has been observed at high latitudes during magnetospheric storms and substorms. He suggested that anomalous processes may affect significantly the height-integrated ionospheric conductances and explain why existing global MHD codes employed for predictive modeling of space weather regularly overestimate cross-polar cap potentials. He showed results of recent theoretical and modeling efforts involving particle-in-cell supercomputer simulations.
COMPUTATIONAL PLASMA PHYSICS GROUP
The F90 version of TSC, which is under source code control using the SVN system, has undergone some key verification and backwards compatibility tests and has had some requested new capabilities added. We have reproduced a CMOD simulation in which LSC is used to provide the Lower Hybrid heating and current drive sources, an ITER disruption calculation from 1997 which involved large vessel forces from the halo currents, and an ITER discharge simulation of current rampup and 550 seconds into the burn phase. In the course of doing the latter, new time-dependent input has been added so that up to seven different impurity fractions as well as H-mode pedestal parameters can be specified as a function of time. Previously these parameters could only be changed by restarting the calculation. This SVN version now has all the capabilities of all previous versions and is the one being used by the SWIM project and all other new activities.
May 14, 2010
THEORY GROUP:
On May 5-7, Dr. L. Zakharov attended the Fifth PRC-US Magnetic Fusion Collaboration Workshop in Wuhan, China. In his talk on "Magnetic measurements for understanding disruptions in tokamaks", he explained the uniqueness of the design of J-TEXT machine in the Huazhong University of Science and Technology (HUST) for tokamak disruption studies. Dedicated magnetic measurements were proposed and discussed with the J-TEXT team and its leadership. On May 12 he gave a seminar at the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP) on "Burning plasma regimes in Fission-Fusion Research Facility (FFRF)". Proposed as an option for the next step in the Chinese fusion program, FFRF would have 50-100 MW of fusion power (Ipl=5 MA, B=4-6 T, PNBI= 5 MW) in the "hot ion" regime, where electron synchrotron radiation expels the alpha heating power from the plasma and keeps the electron temperature limited. More than an hour duration of inductively driven discharge is predicted by the ASTRA-ESC calculations. These special properties of the plasma regime make FFRF consistent with its fusion-fission hybrid mission
May 7, 2010
THEORY GROUP
Dr. Ernesto Mazzucato gave a seminar entitled, "A midsize tokamak for burning plasma studies" on May 6. He suggested that we should redirect our present effort on the development of fusion reactors towards synergistic international collaboration – without relying on a single experiment for addressing the physics of burning plasmas, and we should begin immediately the design and construction of a midsize tokamak capable of reaching large values of energy gain. In his talk, he discussed the possibility of achieving this goal using a tokamak where plasma recycling is minimized with a more efficient divertor than those currently used in tokamaks.
COMPUTATIONAL PLASMA PHYSICS GROUP
Researchers at UC Davis have completed 150 reflectometer simulations using Elfresco, PPPL's web interface to the 2-D Full Wave Reflectometer code. In collaboration with PPPL an extensive numerical survey of candidate microwave imaging reflectometry (MIR) configurations for KSTAR is being performed. The key design issue is establishing appropriate boundary conditions for the optical receiver and illumination systems. Optical systems meeting the constraints imposed by physical limitations, such as port size and tokamak dimensions, must preserve the coupling of transmitter and receiver phase information within well defined standards. In some cases several frequencies from multiple receivers are correlated to identify fluctuation and turbulence in the plasma. This has produced nearly 5,000 runs originating from the web service.
April 30, 2010
THEORY GROUP
Some members of the Theory Department attended the 2010 International Sherwood Fusion Theory Conference held April 19-21, in Seattle, Washington. Allan Reiman gave a talk on, “Three-Dimensional Equilibria with Stochastic Regions Supporting Finite Pressure Gradients”. Joshua Breslau presented a poster titled, "Linear and Nonlinear Properties of a Non-resonant Internal Mode in NSTX". W. W. Lee presented a poster entitled "On Equilibrium Zonal Flows and Diamagnetic Drifts". Roscoe White presented a poster, "Beam particle distribution modification by low amplitude Modes", R. B. White, N. Gorelenkov, W.W. Heidbrink, M.A. Van Zeeland. Janardhan Manickam presented a poster, "Simulation of experimental diagnostics, an investigative tool for MHD instabilities". Jeffery Parker, a graduate student working under the guidance of Roscoe White, presented a poster titled, " TAE-Particle Interaction in Toroidal Plasma Confinement Devices". Morrell Chance presented a poster, "Interfacing VACUUM to M3D-C1" M. S. Chance, S. C. Jardin, N. Ferraro and J. A. Breslau.
The paper, "Nonlinear simulation of toroidal Alfvén eigenmode with source and sink," by J. Lang, G.-Y. Fu, and Y. Chen, was published in Physics of Plasmas. The paper describes recent simulation results of the nonlinear dynamics of energetic particle-driven toroidal Alfvén eigenmode with collision and source/sink using M3D-K code.
Prof. Mikhail Medvedev from the Institute for Advanced Study gave a seminar entitled, " Radiation diagnostic of sub-Larmor-scale magnetic fields in lab and astrophysical plasmas " on April 29. In the talk, he discussed spectral and temporal properties of radiation emitted by relativistic electrons in the course of the Weibel instability development and saturation. In the study he considered (i) anisotropic magnetic fields and electron velocity distributions, (ii) the effects of trapped electrons and (iii) extends the description to large deflection angles of radiating particles thus establishing a cross-over between the classical jitter and synchrotron regimes. The analytical and numerical results obtained from particle-in-cell simulations of the classical Weibel instability was presented. He showed that radiation emitted has a markedly non-synchrotron spectral energy distribution, which can be use as a benchmark of the sub-Larmor-scale magnetic fields in the system.
Dr. Jian-Zhou Zhu, a visiting scholar from University Maryland gave a seminar entitled, "Gyrokinetic statistical absolute equilibrium and turbulence " on April 30. In his talk, he took the absolute equilibrium of Galerkin-truncated inviscid systems to study gyrokinetic plasma turbulence. He showed the existence of negative temperature states for the case of two spatial and one velocity dimension. That indicates a generic feature of inverse energy cascade. He showed that some classical results, such as those of Charney-Hasegawa-Mima are reproduced in the cold-ion limit and there is a universal shape for statistical equilibrium of gyrokinetics in three spatial and two velocity dimensions with just one conserved quantity.
COMPUTATIONAL PLASMA PHYSICS GROUP
Dr. Nakamura, from JAERI, spent the week at PPPL collaborating on the joint PPPL/Japan/India ITER task on TSC disruption analysis of ITER. During the week he performed calculations on the location of the "neutral point" in the redesigned ITER vacuum vessel and participated in a planning conference call with the US and India delegations.
April 23, 2010
THEORY GROUP
Seven members of the Theory Department attended the 2010 Transport Task Force Workshop, April 13-16, in Annapolis, MD: Harry Mynick gave an invited talk entitled, "Optimizing stellarators for turbulent transport"; Taik Soo Hahm gave a talk entitled, “Role of fine scale zonal flows in isotopic dependence of confinement.”; Jianying Lang gave a talk entitled, "Nonlinear Saturation of Toroidal Alfvén Eigenmodes with Turbulence-induced Diffusion"; Weixing Wang gave a talk entitled, "Nonlinear Flow Generation by Electrostatic Turbulence in Tokamaks"; Nikolai Gorelenkov gave an oral presentation entitled, “Equilibrium with anisotropy and flow” by N.N.Gorelenkov and S. Jardin; Guoyong Fu gave a contributed talk entitled, "Development of a Gyrokinetic/MHD Hybrid Code GKM"; Daren Stotler presented a poster entitled, "Verification of a Coupled Kinetic Plasma - Neutral Transport Code: Energy Conservation".
COMPUTATIONAL PLASMA PHYSICS GROUP
The SWIM framework has been used to combine TSC and the TRANSP neutral beam energy deposition and current drive package NUBEAM to perform a free-boundary transport simulation of NSTX shot #124379 from 0.1 to 0.70 seconds, using the same time-dependent values for the coil currents as used in the experimental discharge. The theory-based TSC transport model closely reproduced the measured temperatures in the experiment and all the poloidal flux-loop values were in excellent agreement with the experimental measurements. Stability analysis of the simulated discharge was able to closely reproduce the onset of a non-resonant quasi-stationary m=1 mode. This work was presented at the Sherwood Theory meeting in the paper: "Predictive Modeling of the Onset of a Non-Resonant Internal Mode in NSTX".
April 16, 2010
THEORY GROUP
Daren Stotler attended the Center for Plasma Edge Science Spring All-Hands Meeting, April 11-12, in Annapolis, MD, and gave a talk entitled,, "Running XGC0 - DEGAS 2 Code".
As chair of the Edge Coordinating Committee (ECC), Daren Stotler led the organization of a half-day ECC workshop on the FY2010 and FY2011 Joint Research Milestones on Scrape-Off Layer Heat Transport and H-mode Pedestal, respectively, on April 12, in Annapolis, MD. The meeting provided an opportunity for communication between the experimentalists responsible for completing the FY2010 milestone and theorists having pertinent expertise and simulation capabilities, as well as identifying ways the ECC can facilitate completion of the FY2011 milestone.
Daren Stotler presented a poster entitled "Verification of a Coupled Kinetic Plasma - Neutral Transport Code: Energy Conservation" at the 2010 Transport Task Force Workshop, April 13-16, in Annapolis, MD.
April 9, 2010
THEORY GROUP
Dr. Leonid E. Zakharov gave a seminar entitled, "The needs in disruption simulations: Disruption Simulation Code System (DSCS)" on April 8. In the talk, he outlined the outstanding issues related to understanding disruptions and creation of plasma physics models and numerical codes for their simulations. He proposed that free boundary MHD codes linked with the boundary physics and particle kinetics should be developed to obtain capabilities for addressing urgent ITER needs.
COMPUTATIONAL PLASMA PHYSICS GROUP
The book: Computational Methods in Plasma Physics by Steve Jardin [CRC Press: Boca Raton, ISBN-10: 1439810214 (368 pages)], has now been published and is available in hardcover. The book is an outgrowth of the notes for a Princeton University course of the same name, AST560, which the author has taught to mostly graduate students for the last 20+ years. It covers basic concepts for the numerical solution of partial differential equations, as well as the derivation and motivation for specialized techniques for solving the equations of plasma equilibrium, linear and nonlinear stability and evolution, and transport in a confinement geometry with a strong background magnetic field.
Dr. David Green of ORNL visited PPPL for discussion of strategy for introduction of a quasilinear diffusion based RF Monte Carlo operator in the NUBEAM fast ion model. Discussions ranged from technical details concerning use of the TRANSP/NUBEAM code development system, to discussions with RF physicists at PPPL and MIT on choices for representation of RF operator data and compatibility with currently used RF codes. The research significance of the topic is that many experiments observe evidence of strong coupling between ICRF wave fields and neutral-beam injected fast ions.
April 2, 2010
THEORY GROUP
Dr. Alexey Balakin from Institute of Applied Physics RAS, Nizhny
Novgorod, Russia, gave a seminar entitled, "Quasi-optical Beams in
Inhomogeneous Warm Magnetized Plasma," on April 1. He presented a
quasi-optical description of the propagation and damping of the slowly
varying wave amplitude across an arbitrary electron cyclotron wave
beam. He showed that this model allows an accurate description of the
wave beam evolution in the region of electron cyclotron power
deposition, where the latter condition is quite generally broken. He
also discussed the additional physical effects from spatial
inhomogeneity and dispersion included in the quasi-optical model in
relation to their consequences for the power deposition profile. And
the importance of these effects is analyzed in a number of scans
varying the injection geometry for typical conditions in both the ITER
and the TEXTOR tokamak.
A paper entitled, "Nonlinear Simulation of Toroidal Alfven Eigenmode
with Source and Sink," by Jianying Lang, Guo-Yong Fu, and Yang Chen
(University of Colorado at Boulder), has been accepted for publication
in Physics of plasmas. The abstract reads as follows: Kinetic/
Magnetohydrodynamic (MHD) hybrid simulations are carried out to
investigate the nonlinear dynamics of energetic particle-driven
Toroidal Alfven eigenmode with collision and source/sink. For cases
well above marginal stability, the mode saturation is approximately
steady state with finite collision frequency. The calculated scaling
of saturation level with collision frequency agrees well with analytic
theory. For cases near marginal stability at low collision rates, the
mode saturation exhibits pulsation behavior with frequency chirps up
and down.
COMPUTATIONAL PLASMA PHYSICS GROUP
A numerical aid term has been added to Isolver’s free boundary MHD
equilibrium solver in TRANSP, to improve convergence properties
without affecting accuracy of final results. This has resulted in
about a factor of two improvement in the non-linear solver’s average
convergence iteration count, with a commensurate significant
improvement in computational efficiency. The new method has been
applied to challenging NSTX cases with promising results. The model of
free boundary MHD equilibrium time evolution covering the NSTX shot’s
one second duration is completed in less than half an hour of serial
compute time, which is in the range needed for practical applicability
for offline analysis.
March 26, 2010
THEORY GROUP
Dr. Leonid E. Zakharov gave a theory seminar entitled, "Burning plasma regimes of FFRF" on March 25. In the talk, he outlined the basic aspects of plasma regimes of Fusion-Fission Research Facility (FFRF, R/a=4/1 m/m, Ipl=5 MA, Btor=4-7 T, P_DT=50-100 MW, Pfission=80-4000 MW, 1 m thick blanket), and suggested as the next step device for Chinese fusion program.
COMPUTATIONAL PLASMA PHYSICS GROUP
Stephane Ethier gave a tutorial on parallel debugging at Princeton University as part of the PICASso program of the Princeton Institute for Computational Science and Engineering (PICSciE). The course, entitled, “Introduction to Parallel Debugging”, aimed at introducing the participants to different approaches for tackling the difficult task of debugging multi-processor codes. The tutorial was attended by researchers and graduate students from several science departments at Princeton University.
March 19, 2010
THEORY GROUP
Eric J. Lerner from Lawrenceville Plasma Physics, Inc., gave a seminar entitled, "Theory of the Dense Plasma Focus: Basic Model and Recent Developments" on March 18. He presented the possible use of the dense plasma focus devices for p-B11 fusion. He discussed the basic model, the evidence for dense plasma physics and its current state of development, as well as recent theoretical developments, including the use of an axial magnetic field to maximize the energy transfer to the plasmoids, and the potential for the quantum magnetic field effect to reduce bremsstrahlung emission from a p-B11 plasma in the dense plasma focus.
A paper has been accepted for publication by Plasma Physics and Controlled Fusion by N.N. Gorelenkov, N. Fisch and E. Fredrickson entitled "On the Anomalous Fast Ion Energy Diffusion in Toroidal Plasmas Due to Cavity Modes". In this work, recent detailed observations of high-frequency compressional Alfven eigenmodes on the National Spherical Torus Experiment (NSTX) and their theoretical interpretation are discussed, which support the existence of related modes on the TFTR tokamak, where an enormous wave-particle (fast ion) diffusion coefficient along paths suitable for alpha channeling had been deduced. The eigenmodes responsible for the high frequency magnetic activity can be identified as compressional Alfven eigenmodes through the polarization of the observed magnetic field oscillations in NSTX, and through a comparison with the theoretically derived dispersion relation. The paper shows how these recent observations of high-frequency compressional Alfven eigenmodes lend support to this explanation of the long-standing puzzle of anomalous fast ion energy diffusion on TFTR. The support of the conjecture that these internal modes could have caused the remarkable ion energy diffusion on TFTR carries significant and favorable implications for the possibilities in achieving the alpha channeling effect with small injected power in a tokamak reactor.
Ernest Valeo attended the 2010 US-Japan Workshop on RF Physics, hosted by General Atomics, March 8-10. He described RF SciDAC research in a presentation entitled, "Recent Progress in Self-Consistent Full-Wave Lower Hybrid Simulations."
A. Reiman, G. Fu and D. Stotler attended a Fusion Simulation Project (FSP) planning meeting in Boulder, Colorado from March 15-18. They participated in developing the roadmaps and lists for required software components for the program definition phase of the FSP.
COMPUTATIONAL PLASMA PHYSICS GROUP
This week we succeeded in running the TSC code fully coupled with the NUBEAM Monte Carlo Neutral Beam heating and current drive package in a production mode using the SWIM framework. This is installed on the STIX computer at PPPL and can use up to 80 processors in parallel. The first application was to model the onset time for an internal instability in NSTX. The run reads in the shot coil currents as a function of time and evolves the temperatures, densities, and plasma current using a fully free-boundary predictive model. Excellent agreement is obtained between the simulated results and the experimental values, and with the calculated and observed onset time of the instability. This work will be presented at the Sherwood Theory and IAEA meetings.
Allen Sanderson from the SCI Institute at the University of Utah visited PPPL last week. He demonstrated the use of a new reader plug-ins for the open-source visualization tool VisIt (https://wci.llnl.gov/codes/visit/), customized for visualizing datasets from PPPL's M3D-C1 and GTC codes. For M3D-C1, the customized reader can now read and interpret the HDF5 data file written by M3D-C1 with all the element data, and puncture plots can now be routinely computed and displayed within VisIt. For the gyrokinetic PIC codes, such as GTC and GTS, the FastBit (https://sdm.lbl.gov/fastbit/) indexing tool developed by the Scientific Data Management group at LBL has now been fully-integrated in VisIt and allows for very fast searches through large datasets of simulation particles. The results of the searches, which are the particles falling within a chosen range of parameters, can then be displayed in VisIt using the "parallel coordinates" tool. This provides a very efficient and easy way to visualize multi-dimensional datasets.
March 12, 2010
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Jardin attended the Joint Meeting of the ITPA MHD Stability Topical Group, and US-Japan workshop on "Physics of MHD Control of Toroidal Plasmas" at the National Institute for Fusion Science, Toki, Japan. He presented a talk on "Integrated MHD Modeling using SWIM". While at the workshop, he also participated in a meeting to discuss intermediate results for the ITER task "Update of TSC code and Simulations of ITER disruptions/VDEs scenarios" where he met with collaboration partners from India and Japan, and also with Dr. Sugihara, the ITER IO Physics Head. Plans were made to meet again in July 2010 at the IO to discuss results obtained by that date in more detail.
February 5, 2010
THEORY GROUP
Dr. Gabriel Plunk from University of Maryland gave a theory seminar entitled, "Dual cascade in two dimensional gyrokinetic turbulence" on Feb. 04, 2010. In his talk, he reviewed the progress of research into a new type of dual cascade which is fundamentally kinetic. That is, the cascade operates via nonlinear phase mixing whereby sub-Larmor and sub-thermal scales are excited in the position and velocity space dependence of the gyrokinetic distribution function. His talk included phenomenological scaling arguments, the Fjortoft argument for dual cascade, relationship to Hasegawa--Mima turbulence, a spectral theory of phase space and collisional entropy production
January 29, 2010
THEORY GROUP
In the DOE-SC announcement this week of the INCITE 2010 awards, scientists from the PPPL Theory Department are the lead PI's for two of the projects in the Fusion Energy Sciences (FES) area and others are co-investigators on two other FES projects that are led by PI's from collaborating institutions. The INCITE (Innovative and Novel Computational Impact on Theory and Experiment) program promotes cutting-edge research that can only be conducted with state-of-the-art super-computers. PPPL recipients include: Weixing Wang as PI of the new project on "Investigation of Multi-Scale Transport Physics of Fusion Experiments Using Global Gyrokinetic Turbulence Simulations" with Stephane Ethier and Wei-li Lee as co-Investigators; William Tang as PI of the renewed project on " High Resolution Simulations of Global Microturbulence" with Stephane Ethier as co-Investigator; Greg Hammett and David Mikkelsen as co-Investigators on the renewed project led by Bill Nevins of LLNL on "Validation of Plasma Microturbulence Simulations for Finite-Beta Fusion Experiments;" and Stephane Ethier as co-Investigator on the renewed project led by Pat Diamond of UCSD on "Verification and Validation of Petascale Simulations of Turbulent Transport in Fusion Plasmas." Detailed descriptions of these projects are located on the INCITE 2010 Awards Announcement web-site: http://www.er.doe.gov/ascr/incite/index.html .
COMPUTATIONAL PLASMA PHYSICS GROUP
In a successful modernization effort, the source code server for the PPPL TRANSP codebase was upgraded from cvs to svn. Using the public domain cvs2svn software, the code’s entire cvs collaborative development history, going back to February 1993, was preserved, with 13,180 discreet code modification commit actions recorded. Individual TRANSP developers are able to transition from cvs to svn with a modest effort. The svn service offers a number of improvements in convenience and functionality. For example, certain shareable source components, such as Plasma State, can be imported from TRANSP into other projects using “svn external”. Access requests are handled on a case by case basis. For details see the TRANSP website http://w3.pppl.gov/TRANSP <http://w3.pppl.gov/TRANSP> , follow the “Source Code” link.
Dr. Samuel Lazerson, from the University of Alaska, presented a CPPG seminar on “Numerical Techniques in Dusty Plasmas”. He described The Dust Electron Neutral Ion Self-consistent Integration Scheme (DENISIS) code, a multi-fluid code capable of performing simulations of large-scale dusty plasma phenomena and treating their partially ionized nature. He described the comprehensive validation and testing methodology used for these codes, including linear wave mode propagation, tests of source terms, and convergence testing.
January 22, 2010
THEORY GROUP
An article entitled, "Transport of Parallel Momentum by Toroidal Ion Temperature Gradient Instability near Marginality" by E.S. Yoon and T.S. Hahm has been accepted for publication in the special issue of Nuclear Fusion for the International Workshop for H-mode Physics and Transport Barriers. The abstract reads as follows: The turbulent angular momentum flux carried by ions resonant with toroidal ion temperature gradient (ITG) instability is calculated via quasilinear calculation using the phase-space conserving gyrokinetic equation in the laboratory frame. The results near ITG marginality indicate that the inward turbulent equipartition (TEP) momentum pinch [Hahm T.S. et. al., 2007 Phys. Plasmas 14 072302] remains as the most robust part of the pinch. In addition, the ion temperature gradient driven momentum flux is inward for typical parameters, while the density gradient driven momentum flux is outward as in the previous kinetic result in slab geometry [Diamond P.H. et. al., 2008 Phys. Plasmas 15 012303].
On January 18-20, Leonid E. Zakharov attended the NIFS-CRC International Symposium on Plasma Surface Interactions, CRC-NIFS, Toki, Gifu, Japan and gave a talk, "LiWall Fusion - the new concept of magnetic fusion".
COMPUTATIONAL PLASMA PHYSICS GROUP
The ray tracing code GENRAY has been installed in TRANSP. GENRAY is a code developed and maintained by Dr. Robert Harvey and others at CompX in San Diego. TRANSP can now perform ECRH heating and current drive calculations with GENRAY. The TRANSP documentation page at http://w3.pppl.gov/~pshare/help/transp.htm contains instructions for incorporating the GENRAY capability in a TRANSP run.
January 15, 2010
THEORY GROUP
Daren Stotler and Ravi Samtaney participated in the Proto-FSP Frameworks Workshop, January 11-13, at Oak Ridge National Laboratory on behalf of the Center for Plasma Edge Simulation. Each day of the workshop focused on the simulation framework being used by one of the three SciDAC prototype Fusion Simulation Program projects, including introductory material, demonstrations, and hands-on exercises.
Joshua Breslau attended Department of Energy and White House ceremonies in Washington on January 13 to receive a 2009 Presidential Early Career Award for Scientists and Engineers (PECASE). The citation reads, "For playing an essential role in the development of the massively parallel fusion magnetohydrodynamics code, M3D, and for original and unique applications of this code to the nonlinear dynamics of tokamak instabilities."
COMPUTATIONAL PLASMA PHYSICS GROUP
S. Jardin, D. McCune, and R. Samtaney, together with D. Stotler (PPPL Theory) attended the three-day Workshop of the Three Proto-FSP projects at ORNL. The three projects, CPES: Center for Plasma Edge Simulation, CSWIM: The Center for Simulation of Wave Interaction with MHD, and FACETS: Framework Application for Core-Edge Transport Simulation, each spent one day giving a tutorial on how to use the software and frameworks developed within their projects. It was a hands-on workshop where the attendees gained actual experience in using each of the different frameworks to solve a fusion simulation problem. Each of the three projects has at least one member of the PPPL Computational Plasma Physics group as a participant.
January 8, 2010
THEORY GROUP
An article entitled, "Nonlinear Simulation of Toroidal Alfv\'en Eigenmode with Source and Sink" by J. Lang, G.-Y. Fu, and Y. Chen (University of Colorado at Boulder) has submitted to Phys. Plasmas. The abstract reads as follows: Kinetic/MHD hybrid simulations are carried out to investigate the nonlinear dynamics of energetic particle-driven Toroidal Alfv\'en eigenmode with collision and source/sink. For cases well above marginal stability, the mode saturation is approximately steady state with finite collision frequency. The calculated scaling of saturation level with collision frequency agrees well with analytic theory. For cases near marginal stability at low collision rates, the mode saturation exhibits pulsation behavior with frequency chirps up and down.
COMPUTATIONAL PLASMA PHYSICS GROUP
The NTCC now includes a "data component", based on the Plasma State software, which allows SciDAC Fusion Simulation Program (FSP) prototype codes to access output data of TRANSP simulations. This can be a means for FSP prototypes such as SWIM, FACETS, and CPES to access experimental data such as temperature and density profiles, as well as heating and
current drive sources and fast ion pressures obtained from the experimental analysis.
Dr. Alexander Pletzer, from TechX, Boulder, CO, visited this week and presented a CPPG seminar titled: "Chompst: Marrying the best of Chombo and PETSc for solving "hard" Multi-grid problems". Chompst is a Small Business Innovation & Research (SBIR) project funded by DoE to address the need for exposing the large collection of PETSc iterative solvers
from within the adaptive mesh refinement (AMR) tool Chombo. Standard multi-grid is known to be ill-suited for some elliptic operators, notably some Helmholtz operators, and thermal diffusion problems where the heat conductivity is highly anisotropic and/or exhibits strong spatial dependency. In his talk, he showed how the ability to go beyond multi-grid relaxation schemes by exposing PETSc's rich set of iterative solvers will allow Chombo users to solve some of these hard problems.
This website is maintained by Jennifer Jones
|
|
