Princeton
Plasma Physics
Laboratory
THEORY
DEPARTMENT
Listed
below are the Theory Seminars Scheduled for 20052006
Theory
seminars, 20042005
Date

Speaker

Affiliation

Title

Comments

September
20

Philipp Lauber

IPP, Garching,Germany

Linear Gyrokinetic Calculations on the Kinetic
Properties of Shear Alfven Modes in Tokamak Plasmas

Seminar will be held on Tuesday, September 20 at 2:15
pm, T 169

September
27

Bill Nevins

Lawrence Livermore National Lab

Discrete
Particle Noise in ParticleinCell Simulations of
Plasma Microturbulence 
Seminar
will be held on Tuesday, September 27 at 10:45 am, T 169 
October
13

Allen
Boozer

Columbia
University

Magnetic reconnection in nontoroidal
plasmas


November
3

H.C. Yee

NASA Ames Research Center

Adaptive Flow Sensor in High Order Methods for Complex
Multiscale Flows


November 04

Dmytro Sydorenko

University of Saskatchewan

Particleincell simulation of kinetic effects in
lowpressure plasmas

Informal Talk, Friday, November 4 at 3:00 pm, T 169 
November
10

Nuno Loureiro

CMPD, University of Maryland and PPPL

Nonlinear evolution of the tearing mode


December 8

Norman J. Zabusky

Rutgers University

Overview of RichtmyerMeshkov flows: From the vortex
paradigm to vortex double layers and baroclinic turbulence


January 26 
Ilya Y. Dodin 
Princeton University 
Nonadiabatic Ponderomotive Barriers 

February 2 
Frank Cheng 
National Space Organization 
Space Science Program in Taiwan 

February 24 
Nuno Loureiro 
CMPD, University of Maryland 
Nonlinear Evolution of the Tearing Mode 
Seminar will be held on Friday, 2/24 at 11 am in T 169 
April 13 
Scott Tremaine 
Princeton University 
The Longterm Stability of Planetary Systems 

April 27 
Jerome Lewandowski 
Princeton Plasma Physics Lab 
Particleincell simulations of electromagnetic
microturbulence with fully kinetic ions and electrons

Seminar will be held in the Display Wall Room  A 104. 
May 9 
Bruce Scott 
MaxPlanckInstitut Fuer Plasmaphysik, Euratom Association,
Garching, Germany 
Energetics in fullf and deltaf gyrokinetic equations 
Seminar start time will be 11:00 am. Special Tuesday
seminar. 
June 8 
Prateek Sharma 
Department of Astrophysical Sciences, Princeton University 
Kinetic effects in astrophysical plasmas 

June 15 
Roman Kolesnikov 
PPPL 
High frequency gyrokinetic particle simulation


July 6 
Zhe Gao 
Department of Engineering Physics
Tsinghua University

Multiple Eigenmodes of Geodesic Acoustic Mode in
Collisionless
Plasmas


Tuesday,
September 20,
2:15 pm
Philipp
Lauber
IPP,
Garching, Germany
Linear
Gyrokinetic Calculations on the Kinetic Properties of Shear
Alfve'n Modes in Tokamak Plasmas
The
ability to predict the stability of fastparticledriven
Alfven
eigenmodes in burning fusion plasmas requires a detailed
understanding of the mechanisms that drive and damp these
modes. In order to address this question, the linear
gyrokinetic, electromagnetic code LIGKA is employed to
investigate their behaviour in realistic tokamak geometry.
LIGKA is based on an eigenvalue formulation and
selfconsistently and
nonperturbatively calculates the coupling of largescale
MHD modes to
gyroradius scale length kinetic Alfven waves. It uses the
driftkinetic HAGIS code to accurately describe the
unperturbed particle orbits in general geometry. In
addition, a newly developed antennalike version of LIGKA
allows for a frequency scan, analogous to an external
antenna.With these tools the properties of the kinetically
modified TAE in or near the gap (KTAE, radiative damping or
`tunneling') and its coupling to the continuum can be
analysed.

Tuesday,
September 27,
10:45 am
Bill
Nevins, Lawrence Livermore National Lab, Livermore, CA
Title:
Discrete Particle Noise in ParticleinCell Simulations of
Plasma Microturbulence
Abstract:

Thursday,
October 13, 10:45 am
Allen Boozer, Columbia Univesity,
New York, NY
Title: Magnetic
reconnection in nontoroidal plasmas
Abstract: Magnetic
reconnection is a major issue in solar and
astrophysical plasmas. The mathematical result that the
evolution of a
magnetic field with only point nulls is always locally ideal
limits the
nature of reconnection in nontoroidal plasmas. Here it is
shown that the
exponentially increasing separation of neighboring magnetic
field lines,
which is generic, tends to produce rapid magnetic
reconnection if the
length of the field lines is greater than about 20 times the
exponentiation,
or Lyapunov, length.
A copy
of Dr. Boozer's seminar presentation is available here.

Thursday,
November 3, 10:45 am
H.C. Yee, NASA Ames
Research Center, Moffett Field, CA
Title: Adaptive Flow Sensor
in High Order Methods for Complex Multiscale Flows
This seminar discusses an adaptive
numerical dissipation control
in high order nonlinear filter methods. This nonlinear
filter
is very general and can be used in conjunction with
spectral,
finite element, finite volume, and finite difference
compact and noncompact spatially central base schemes.
The nonlinear filter method consists of two steps, a
divergencefree
preserving base scheme step (not involving the use of
approximate
Riemann solvers or flux limiters) and a nonlinear filter
step
(usually involving the use of approximate Riemann solvers
and flux limiters). The adaptive filter consists of
automatic detection of different flow features by distinct
sensors
to! signal the appropriate type and amount of numerical
dissipation
where needed while leaving the rest of the region free of
numerical
dissipation contamination. These schemeindependent flow
sensors are
capable of distinguishing shocks/shears, flame sheets,
turbulent
fluctuations and spurious highfrequency oscillations. In
addition,
these sensors are readily available as an improvement over
existing
grid adaptation indicators. The flow sensor algorithm is
based on
redundant multiresolution wavelets. One of the unique
features of the
numerical method is that it is suitable for nearly
incompressible to
highly compressible gas dynamics and MHD flows. It is also
stable and
accurate for a wide spectrum of flow physics ranging from
long time wave
propagation of smooth flows to high speed multiscale
turbulent/combustion
flows including strong shock waves.

Friday, November
4, 3:00 pm
Informal Talk
Dmytro Sydorenko, University of
Saskatchewan in collaboration with A.Smolyakov,
I. Kaganovich, and Y. Raitses.
Title: Particleincell simulation of
kinetic effects in lowpressure pla
smas
Several particleincell codes have been
developed for simulations of different plasma devices, such
as dielectric
wakefield
accelerators, inductively coupled plasmas, Hall thrusters.
The explicit and implicit schemes have been applied,
including the multiscale algorithms and the parallel
programming. The emphasis is made on the simulations of
plasmawall interaction in Hall thrusters. The nonMaxwellian
electron velocity distribution function is obtained; it is
strongly anisotropic, depleted at high energy, and
nonmonotonic. Secondary electrons form two
counterpropagating beams; their propagation is determined
by collective effects. It is shown that such modification of
the electron velocity distribution function drastically
changes the particles and heat losses to walls.

Thursday,
November 10, 10:45 am
Nuno Loureiro, CMPD, University of
Maryland and PPPL
Title: Nonlinear evolution of the tearing
mode
The strongly driven (large D') tearing
mode is thought to be of
relevance in connection to the sawtooth problem in tokamaks
and general
reconnection phenomena in space and astrophysical plasmas.
Although some efforts have been made to analytically
describe this
region of parameter space (e.g., Coppi et al. 76, Waelbroeck
89,93), the
large computational requirements for a thorough study have
meant that
this regime of the tearing instability has remained largely
unstudied.
In this talk, I present recent numerical results on the
nonlinear
evolution of the strongly and weakly driven resistive
tearing mode. Slab
geometry is adopted and the equations of reducedMHD (RMHD)
are used.
A highresolution numerical scan of the parameter space (D',eta)
shows
that, in general, the tearing mode evolves through five
stages:
exponential growth, algebraic growth (Rutherford stage),
Xpoint collapse followed by currentsheet exponential
reconnection
(SweetParker stage), tearing instability of the current
sheet
(generation of secondary islands), and saturation. The
Xpoint collapse
occurs at a critical island width that scales as Wc ~ 1/D'.
During the
collapse, reconnection proceeds with a rate proportional to
eta^{1/2}.
The resulting current sheet becomes unstable if it has a
lengthtowidth
ratio that exceeds a certain critical value. Secondary
islands are then
formed, the evolution of which occurs in a selfsimilar way
to the original
perturbation. At low D', the saturation amplitude is shown
to be in good
agreement with recent analytic theories. At large D' we show
that the saturated
amplitude depends on the existence of a previous collapse.

Thursday, December 8, 10:45 am
Norman J. Zabusky, Rutgers University
Title: Overview of RichtmyerMeshkov
flows: From the vortex paradigm to vortex double layers and
baroclinic turbulence
We
review, history, relevance,
progress and models for the impulsive
RayleighTaylor or RichtmyerMeshkov accelerated
inhomogeneous flow (AIF) environments. We emphasize
vortexrelated physical phenomena to lateintermediate
times. We review
linear stability analyses and examine several fundamental
geometrical configurations, where important secondary
baroclinic vortex processes determine the essential
evolution. Included are the shock accelerated : classical
singlemode sine wave; planar inclined interface; planar
inclined “curtain”; and cylinder. Comments will be made about: wellposedness and interfacial transition
layers; Mach and Atwood number parameter ranges;
comparison with experiments;
resolution and artificial viscous effects;
diagnostics for validation and understanding; and models
beyond early times.
*Collaborators:
Dr. Shuang Zhang (Fluent, Inc) & Gaozhu Peng;

Thursday, January
26, 10:45 am Ilya Y. Dodin,
Astrophysical Sciences Department, Princeton University
Title: Nonadiabatic Ponderomotive Barrier
A ponderomotive potential is an effective
potential seen by a
particle in ac field in average over the fast oscillations.
It is not
a true potential though, and, if the ac field is in
resonance with
particle natural oscillations, the particle can exhibit
irreversible
drift motion [13]. A new ponderomotive potential is found
for this
case that can capture nonadiabatic dynamics [4]. The
particle drift
in this new potential resembles the motion of a quantum
object in a
conservative field [5]. Among other applications, these
nonadiabatic
potentials can perform selective separation and cooling of
plasma
species or drive electric current by asymmetrically
transmitting
thermal particles in a preferential direction [1, 2, 6].
[1] N.J. Fisch, J.M. Rax, and I.Y. Dodin, Phys. Rev. Lett.
91, 205004
(2003).
[2] I.Y. Dodin, N.J. Fisch, and J.M. Rax, Phys. Plasmas 11,
5046
(2004).
[3] I.Y. Dodin and N.J. Fisch, J. Plasma Phys. 71, 289
(2005).
[4] I.Y. Dodin and N.J. Fisch, Phys. Lett. A 349, 356
(2006).
[5] I.Y. Dodin and N.J. Fisch, Phys. Rev. Lett. 95, 115001
(2005).
[6] I.Y. Dodin and N.J. Fisch, Phys. Rev. E 72, 046602
(2005).

Thursday,
Februrary 2, 10:45 am Frank
Cheng, National Space Organization
Title: Space Science Program in Taiwan
Taiwan's first phase space program was
initiated in 1991 for a 15year period and its goal is to
establish necessary domestic infrastructure and carry out
satellite programs. During this period Taiwan has
established a satellite integration and test facility and
launched two satellite missions (FORMOSAT1 and FORMOSAT2)
and will launch in March, 2006 the FORMOSAT3 mission which
consists of six microsatellites. The science objective of
these missions will be described. The second phase 15year
space program started in 2004 and the goal is to establish
the selfreliant capability in space science and technology
for satellite mission. Presently one satellite mission is
planned for every 3 to 4 years and sounding rocket
experiments are planned for once or twice per year. A
dualpurpose satellite mission, ARGO, is now planned for
launch in late 2008. International collaboration will be a
key element to achieve the second phase program goal.

Friday, February
24, 11:00 am Nuno Loureiro, CMPD, University of
Maryland and PPPL
Title: Nonlinear Evolution of the Tearing
Mode
The strongly driven (large D') tearing
mode is thought to be of relevance in connection to the
sawtooth problem in tokamaks and general reconnection
phenomena in space and astrophysical plasmas. Although some
efforts have been made to analytically describe this region
of parameter space (e.g., Coppi et al. 76, Waelbroeck
89,93), the large computational requirements for a thorough
study have meant that this regime of the tearing instability
has remained largely unstudied.
In this talk, I present recent numerical results on the
nonlinear evolution of the strongly and weakly driven
resistive tearing mode. Slab geometry is adopted and the
equations of reducedMHD (RMHD) are used. A highresolution
numerical scan of the parameter space (D',eta) shows that,
in general, the tearing mode evolves through five stages:
exponential growth, algebraic growth (Rutherford stage),
Xpoint collapse followed by currentsheet exponential
reconnection (SweetParker stage), tearing instability of
the current sheet (generation of secondary islands), and
saturation. The Xpoint collapse occurs at a critical island
width that scales as Wc ~ 1/D'. During the collapse,
reconnection proceeds with a rate proportional to eta^{1/2}.
The resulting current sheet becomes unstable if it has a
lengthtowidth ratio that exceeds a certain critical value.
Secondary islands are then formed, the evolution of which
occurs in a selfsimilar way to the original perturbation.
At low D', the saturation amplitude is shown to be in good
agreement with recent analytic theories. At large D' we show
that the saturated amplitude depends on the existence of a
previous collapse.
This is a repeat of the seminar presented
on November 10, by request.

Thursday, April 13,
10:45 am Scott Tremaine, Dept.
of Astrophysical Science, Princeton University
Title: The longterm stability of
planetary systems
The longterm orbital behavior of
planetary orbits is the mother
of all problems in nonlinear dynamics, but remains
incompletely understood
despite three centuries of study starting with Newton.
Understanding this
behavior is central to many issues of planetary science: Why
are the
planets so regularly spaced? How has the Earth's orbit
evolved throughout
geological history? What determines the properties of the
orbits of
extrasolar planets? Nbody integrations allow us to follow
the motion of
planets reliably for billions of years, and thereby inform
us about the
evolution and current properties of planetary systems, and
the ultimate
fate of the Earth and other planets.

Thursday, April 27,
10:45 am  Display Wall Room (A 104)
Jerome Lewandowski, Theory Department,
Princeton Plasma Physics Lab
Title: Particleincell simulations of
electromagnetic microturbulence with fully kinetic ions and
electrons
A lownoise method suitable for PIC
simulations of
electromagnetic drift wave and ITG microturbulence is
presented. The
splitting scheme is based on an exact separation between
adiabatic and
nonadiabatic responses for each species; such an approach
allows for
noisefree, energyconserving simulations but comes at a
cost:
one must repeatedly solve coupled, nonlinear elliptic
equations for the
various scalar fields. This apparent numerical difficulty is
tackled using
the multigrid method. Simulation results in a simple
geometry will be
presented and generalization to toroidal plasmas will be
discussed.

Tuesday, May 9,
11:00 am
Bruce Scott, MaxPlanckInstitut fuer
Plasmaphysik, Euratom Association, Garching, Germany
Title: Energetics in fullf and deltaf
gyrokinetic equations
The derivation of the deltaf Vlasov
equation starting with
the general gyrokinetic field theory is given. The totalf
version with
Hamiltonian structure serves as intermediary. The main
deltaf
approximation is linearisation of field polarisation and the
parallel
bracket. An energy conserving form is found by applying
deltaf
ordering to the spatial derivatives. The conserved quantity
is the well
known deltaf free energy, related to the entropy. The
conservation
properties are compared to those following from the
application of the
Noether theorem to teh totalf model. Although a different
energy is
conserved, the field/particle transfer terms are the same.

Thursday, June 8,
10:45 am
Prateek Sharma, Department of Astrophysical
Sciences, Princeton University
Title: Kinetic effects in astrophysical
plasmas
Many astrophysical plasmas are
macroscopically collisionless,
with mean free path larger than the system size. Examples
are low
luminosity accretion disks, x ray clusters, solar wind, etc.
In these
cases MHD is not a good approximation. I will describe the
kinetic MHD
approximation (which is valid for scales larger than the
gyroradius and
frequencies smaller than the gyrofrequency, Kulsrud 1983 in
Handbook of
plasma physics) for collisionless plasmas and Landau closure
(Snyder et
al. Phys. Plasmas 1997, 4, 3974) for anisotropic heat
fluxes. I'll discuss
the effects of anisotropic transport on MHD instabilities.
Microinstabilities (mirror, firehose, ioncyclotron, etc.)
are driven by
pressure anisotropy that arises as a natural consequence of
stretching and
shearing of the field lines. I'll discuss how collisionless
effects can be
important for transport in low luminosity accretion disks
and x ray
clusters.

Thursday, June 15,
10:45 am
Roman Kolesnikov, PPPL
Title: High frequency gyrokinetic particle
simulation
This presentation is a part of the ongoing
OASCR/MICS research on
MultiScale Gyrokinetics (MSG) at PPPL. The purpose of this
project is to
develop numerical algorithms for solving gyrokinetic VlasovMaxwell
equations which can potentially handle several orders of
magnitude in both time and space and can eventually be
ported into the global toroidal codes, such as GTC, to
simulate kinetic effects in realistic fusion plasmas. The
focus of the present talk is on the development of the
algorithm which allows one to simulate high frequency
dynamics based on the gyrokinetic formalism assuming only
that the ion gyroradius is smaller than the scale length of
the ambient magnetic field. As an example, we
will present a simple case of ion cyclotron instability
simulation based on the new algorithm using a
twodimensional particleincell code in simple slab
geometry in the
electrostatic limit. The linear and nonlinear properties of
the instabilities obtained from the high frequency
gyrokinetic code will be presented. To illustrate the
nonlinear mechanisms introduced into the gyrokinetic
formalism by the
gyrophase dependent part of the dynamics, and their
importance for
quasilinear ion perpendicular heating, we will make
comparisons with the results from a regular Lorentzforce
code. Discussions of the possible advantages this new
algorithm in comparisons with other approaches used for
studying RF waveplasma interactions will be given.

Thursday, July 6,
10:45 am Zhe Gao, Department of
Engineering Physics Tsinghua University
Title: Multiple Eigenmodes of Geodesic
Acoustic Mode in Collisionless
Plasmas
Both the low/zero frequency zonal flow (ZF)
and higher frequency
oscillating ZF, so called the geodesic acoustic mode (GAM),
first and
foremost, are plasma eigenmodes. The progress of the
experimental
research on multiple GAM oscillations stimulates the
research on various
types of branches in the family of ZFs. In the work, we
employ a linear
gyrokinetic model in collisionless toroidal plasmas with an
electrostatic potential rigid constant around a magnetic
surface, and
then the plasma response is analytically solved for plasma
with circular
cross section and large aspect ratio. Besides the trivial
zero frequency
solution and the standard GAM solution, a branch of low
frequency mode
and a series of ISWlike modes are identified. The ISWlike
modes has a
frequency spectrum roughly with a progression of sqrt(n)
times the
transit frequency and strongly damped. The low frequency
eigenmode has a
rigid zero frequency for low q but oscillates with a finite
frequency
for higher q, and it relaxes on time scaling with the order
of transit
frequency.

