Hantao Ji's Homepage

Hantao Ji

Plasma Physics Laboratory
Forrestal Campus, C-Site, Room L222
Princeton University, PO Box 451
Princeton, NJ 08543

Tel: (609) 243-2162
email: hji@pppl.gov

Astrophysical Sciences
Peyton Hall, Room 106
Princeton University
Princeton, NJ 08540

Tel: (609) 258-8052
email: hji@princeton.edu

I am a Professor at Department of Astrophysical Sciences and a Distinguished Research Fellow at Princeton Plasma Physics Laboratory (PPPL) (try here and here also), Princeton University. I am also the Associate Director and a Co-Principal Investigator of a National Science Foundation (NSF) Physics Frontier Center , Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas (CMSO). I am a Co-Principal Investigator of Center for Momentum Transport & Flow Organization in Plasmas and Magnetofluids (CMTFO) sponsered by the U.S. Department of Energy Office of Fusion Energy Sciences.

Course: AST552 (Part I: Magnetohydrodynamics and Part II: Kinetic Theory) Click here for the course website

News: 2012 US-Japan Workshop on Magnetic Reconnection (MR2012) was successfully held at Princeton University, New Jersey, from May 23 to May 25, 2012. Since the first meeting of this meeting series held also in Princeton back in 1998, scientists from multiple communities, laboratory plasma physics, space plasma physics, solar plasma physics, and astrophysics came together to present and discuss their latest results on the subject of magnetic reconnection. More than 70 scientists from around world attended this meeting and their presentation slides and recorded videos can be found here.

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Major Research Activities

Physics of Magnetorotational Instability (MRI) in a small liquid metal device at PPPL. Selected publications:
- C. Gissinger, J. Goodman, and H. Ji, "The role of boundaries in the magnetorotational instability", Phys. Fluids 24, 074109 (2012). (pdf)
- E. Schartman, H. Ji, M. Burin, and J. Goodman, "Stability of quasi-Keplerian shear flow in a laboratory experiment", Astron. Astrophys. 543, A94 (2012). (pdf)
- E. Spence, A. Roach, E. Edlund, P. Sloboda, and H. Ji, "Free magnetohydrodynamic shear layers in the presence of rotation and magnetic field", Phys. Plasmas 19, 056502 (2012). (pdf)
- A. Roach, E. Spence, C. Gissinger, E. Edlund, P. Sloboda, J. Goodman and H. Ji, "Observation of a Free-Shercliff-Layer Instability in Cylinderical Geometry", Phys. Rev. Lett. 108, 154502 (2012). (pdf)
- C. Gissinger, H. Ji, and J. Goodman, "Instabilities in magnetized spherical Couette flow", Phys. Rev. E 84, 026308 (2011). (pdf)
- M. Nornberg, H. Ji, E. Schartman, A. Roach, and J. Goodman, "Observation of Magnetocoriolis Waves in a Liquid Metal Taylor Couette Experiment", Phys. Rev. Lett. 104, 074501 (2010). (pdf)
- M. Burin, E. Schartman and H. Ji, "Local measurements of turbulent angular momentum transport in circular Couette ﬂow", Exp. Fluids 48, 763 (2010). (pdf)
- E. Schartman, H. Ji and M. Burin, "Development of a Couette–Taylor flow device with active minimization of secondary circulation ", Rev. Sci. Instrum. 80, 024501 (2009). (pdf)
- H. Ji, P. Kronberg, S. Prager, and D. Uzdensky, "Mini-conference on angular momentum transport in laboratory and nature", Phys. Plasmas 15, 058302 (2008). (pdf)
- W. Liu, J. Goodman, and H. Ji, "Traveling waves in magnetized Taylor-Couette flow", Phys. Rev. E 76, 016310 (2007). (pdf)
- W. Liu, J. Goodman, I. Herron, and H. Ji, "Helical magnetorotational instability in magnetized Taylor-Couette flow", Phys. Rev. E 74, 056302 (2006). (pdf)
- H. Ji, M. Burin, E. Schartman, and J. Goodman, "Hydrodynamic turbulence cannot transport angular momentum effectively in astrophysical disks", Nature 444, 343 (2006). (pdf, introduction by S. Balbus)
- W. Liu, J. Goodman, and H. Ji, "Simulation of Magnetorotational Instability in a Magnetized Couette Flow", Astrophys. J. 643, 306 (2006). (pdf)
- M. Burin, E. Schartman, H. Ji, R. Cutler, P. Heitzenroeder, W. Liu, L. Morris, and S. Raftopolous, "Reduction of Ekman Circulation within Circular Couette Flow", Exp. Fluids 40, 962 (2006). (pdf)
- A. Kageyama, H. Ji, J. Goodman, F. Chen, and E. Shoshan, "Numerical and Experimental Investigation of Circulation in Short Cylinders", J. Phys. Soc. Jpn. 73, 2434(2004). (Abstract) (pdf file)
- J. Goodman and H. Ji, "Magnetorotational Instability of Dissipative Couette Flow", J. Fluid Mech. 462, 365(2002). (Abstract) (pdf file)
- H. Ji, J. Goodman, and A. Kageyama, "Magnetorotational Instability in a Rotating Liquid Metal Annulus", Monthly Notices of Royal Astronomical Society 325, L1(2001). (Abstract) (pdf file)
Plasma-material interactions (PMI) including areas of low-temperature plasma physics and free-surface liquid metal flow for heat removal. Selected publications:

C. Jin, T. Yu, Y. Zhao, Y. Bo, C. Ye, J. Hu, L. Zhuge, S. Ge, X. Wu, H. Ji, and J. Li, "Helicon Plasma Discharge in a Toroidal Magnetic Field of the Tokamak", IEEE Trans. Plasma Sci. 39, 3103 (2011). (pdf file)
M. Nornberg, H. Ji, J.L. Peterson, and J.R. Rhoads, "A liquid metal flume for free surface magnetohydrodynamic experiments", Rev. Sci. Instru. 79, 094501 (2008). (pdf)
H. Ji, W. Fox, D. Pace, and H. Rappaport, "Study of Magnetohydrodynamic Surface Waves in Liquid Gallium", Phys. Plasmas 12, 012102 (2005). (Abstract) (pdf file)

Physics of magnetic reconnection in the Magnetic Reconnection Experiment (MRX), a small experimental device at PPPL. Selected publications:
- H. Ji and W. Daughton, "Phase diagram for magnetic reconnection in heliophysical, astrophysical, and laboratory plasmas," Phys. Plasmas 18, 111207 (2011) (pdf file)
- E. Zweibel, E. Lawrence, J. Yoo, H. Ji, M. Yamada, and L. Malyshkin, "Magnetic reconnection in partially ionized plasmas", Phys. Plasmas 18, 111211 (2011) (pdf file)
- E. Oz, C. Myers, M. Yamada, H. Ji, R. Kulsrud, and J. Xie, "Experimental verification of the Kruskal-Shafranov stability limit in line-tied partial-toroidal plasmas", Phys. Plasmas 18, 102107 (2011) (pdf file)
- V. Roytershteyn, W. Daughton, S. Dorfman, Y. Ren, H. Ji, M. Yamada, H. Karimabadi, L. Yin, B.J. Albright, and K.J. Bowers, "Driven magnetic reconnection near the Dreicer limit", Physics of Plasmas 17, 055706 (2010). (pdf)
- M. Yamada, R. Kulsrud, and H. Ji, "Magnetic Reconnection", Reviews of Modern Physics 82, 603 (2010). (pdf)
- Y. Wang, R. Kulsrud, and H. Ji, "An analytic study of the perpendicularly propagating electromagnetic drift instabilities in the Magnetic Reconnection Experiment", Physics of Plasmas 15, 122105 (2008). (pdf)
- S. Dorfman, W. Daughton, V. Roytershteyn, H. Ji, Y. Ren, M. Yamada, "Two-dimensional fully kinetic simulations of driven magnetic reconnection with boundary conditions relevant to the Magnetic Reconnection Experiment", Physics of Plasmas 15, 102107 (2008). (pdf)
- Y. Ren, M. Yamada, H. Ji, S. Dorfman, S. Gerhardt, R. Kulsrud, "Experimental study of the Hall effect and electron diffusion region during magnetic reconnection in a laboratory plasma", Physics of Plasmas 15, 082113 (2008). (pdf)
- Y. Ren, M. Yamada, H, Ji, S. Gerhardt, R. Kulsrud, "Identification of the electron-diffusion region during magnetic reconnection in a laboratory plasma", Physical Review Letters 101, 085003 (2008). (pdf)
- H. Ji, Y. Ren, M. Yamada, S. Dorfman, W. Daughton, S. Gerhardt, "New insights into dissipation in the electron layer during magnetic reconnection", Geophysical Research Letters 35, L13106 (2008). (pdf)
- A. Kuritsyn, H. Ji, S. Gerhardt, Y. Ren, M. Yamada, "Effects of global boundary and local collisionality on magnetic reconnection in a laboratory plasma", Geophysical Research Letters 34, L16106 (2007). (pdf)
- M. Inomoto, S. Gerhardt, M. Yamada, H. Ji, E. Belova, A. Kuritsyn, and Y. Ren, "Coupling between Global Geometry and the Local Hall Effect Leading to Reconnection-Layer Symmetry Breaking", Physical Review Letters 97, 135002 (2006). (pdf)
- M. Yamada, Y. Ren, H. Ji, J. Breslau, S. Gerhardt, R. Kulsrud, and A. Kuritsyn, "Experimental study of two-fluid effects on magnetic reconnection in a laboratory plasma with variable collisionality", Physics of Plasmas 13, 052119 (2006). (pdf)
- A. Kuritsyn, M. Yamada, S. Gerhardt, H. Ji, R. Kulsrud, and Y. Ren, "Measurements of the parallel and transverse Spitzer resistivities during collisional magnetic reconnection", Physics of Plasmas 13, 055703 (2006). (pdf)
- Y. Ren, M. Yamada, S. Gerhardt, H. Ji, R. Kulsrud, and A.Kuritsyn, "Experimental Verification of the Hall Effect during Magnetic Reconnection in a Laboratory Plasma", Phys. Rev. Lett. 95, 055003 (2005). (Abstract) (pdf file)
- R. Kulsrud, H. Ji, W. Fox, and M. Yamada, "An electromagnetic drift instability in the magnetic reconnection experiment and its importance for magnetic reconnection", Phys. Plasmas 12, 082301 (2005). (Abstract) (pdf file)
- H. Ji, R. Kulsrud, W. Fox, and M. Yamada, "An obliquely propagating electromagnetic drift instability in the lower hybrid frequency range", J. Geophys. Res. 110, A08212 (2005). (Abstract) (pdf file)
- H. Ji, S. Terry, M. Yamada, R. Kulsrud, A. Kuritsyn, and Y. Ren, "Electromagnetic Fluctuations during Fast Reconnection in a Laboratory Plasma", Phys. Rev. Lett. 92, 115001(2004). (Abstract) (pdf file)
- F. Trintchouk, M. Yamada, H. Ji, R. M. Kulsrud, and T. A. Carter "Measurement of the transverse Spitzer resistivity during collisional magnetic reconnection", Phys. Plasmas 10, 319(2003). (Abstract) (pdf file)
- T. Carter, M. Yamada, H. Ji, R. Kulsrud, and F. Trintchouk "Experimental study of lower-hybrid drift turbulence in a reconnecting current sheet", Phys. Plasmas 9, 3272(2002). (Abstract) (pdf file)
- T. Carter, H. Ji, F. Trintchouk, M. Yamada, and R. Kulsrud, "Measurement of Lower-Hybrid Drift Turbulence in a Reconnecting Current Sheet", Phys. Rev. Lett. 88, 015001(2002). (Abstract) (pdf file)
- Hantao Ji, Troy Carter, Scott Hsu, and Masaaki Yamada, "Study of Local Reconnection Physics in a Laboratory Plasma", Earth Planets Space 53, 539(2001). (Abstract) (pdf file)
- S. Hsu, T. Carter, G. Fiksel, H. Ji, R. Kulsrud, and M. Yamada "Experimental Study of Ion Heating and Acceleration during Magnetic Reconnection", Phys. Plasmas 8, 1916(2001). (Abstract) (pdf file)
- S. Hsu, G. Fiksel, T. Carter, H. Ji, R. Kulsrud, and M. Yamada, "Local Measurement of Nonclassical Ion Heating during Magnetic Reconnection", Phys. Rev. Lett. 84, 3859(2000). (Abstract) (pdf file)
- M. Yamada, H. Ji et al., "Experimental investigation of the neutral sheet profile during magnetic reconnection", Phys. Plasmas 7, 1781(2000). (Abstract) (pdf file)
- H. Ji, "Helicity, Reconnection, and Dynamo Effects", AGU monograph "Magnetic Helicity in Space and Laboratory Plasmas", p.167 (1999). (Abstract) (pdf file)
- H. Ji, M. Yamada et al., "Magnetic Reconnection with Sweet-Parker Characteristics in Two-dimensional Laboratory Plasmas", Phys. Plasmas 6, 1743(1999). (Abstract) (pdf file)
- T.-H. Watanabe, T. Hayashi, T. Sato, M. Yamada, and H. Ji, "Modeling of magnetic island formation in magnetic reconnection experiment", Phys. Plasmas 6, 1253 (1999) (pdf file)
- H. Ji, M. Yamada et al., "Experimental Test of the Sweet-Parker Model of Magnetic Reconnection", Phys. Rev. Lett. 80, 3256(1998). (Abstract) (pdf file)
- M. Yamada, H. Ji et al., "Identification of Y-Shaped and O-Shaped Diffusion Regions during Magnetic Reconnection in a Laboratory Plasma", Phys. Rev. Lett. 78, 3117(1997). (Abstract) (pdf file)
- M. Yamada, H. Ji et al., "Study of Driven Magnetic Reconnection in a Laboratory Plasma", Phys. Plasmas 4, 1936(1997). (Abstract) (pdf file)
Dynamo EMF measurements, magnetic helicity conservation, fluctuation driven transport, confinement improvement in the Madison Symmetric Torus (MST), a medium-sized, toroidal reversed field pinch (RFP) device in the Department of Physics at the University of Wisconsin-Madison. Selected publications:
- K. Kemel, A. Brandenburg, and H. Ji, "Model of driven and decarying magnetic turbulence in a cylinder", Phys. Rev. E 84, 056407 (2011) (pdf file)
- E. Blackman and H. Ji, "Laboratory plasma dynamos, astrophysical dynamos and magnetic helicity evolution", Monthly Notices of Royal Astronomical Society 369, 1837(2006). (pdf file)
- H. Ji and S.C. Prager, "The Alpha Dynamo Effects in Laboratory Plasmas", Magnetohydrodynamics 18, 191(2002). (Abstract) (pdf file)
- H. Ji, "Turbulent Dynamos and Magnetic Helicity", Phys. Rev. Lett. 83, 3198(1999). (Abstract) (pdf file)
- H. Ji, A.F.Almagri, S.C.Prager, and J.S.Sarff, "Time-resolved Observation of Discrete and Continuous MHD Dynamo in the Reversed-Field Pinch Edge", Phys. Rev. Lett. 73, 668 (1994). (Abstract) (pdf file)
- H. Ji et al., "Effect of Collisionality and Diamagnetism on the Plasma Dynamo", Phys. Rev. Lett. 75, 1086 (1995). (Abstract) (pdf file)
- H. Ji et al., "Measurement of the dynamo effect in a plasma", Phys. Plasmas 3, 1935 (1996). (Abstract) (pdf file)
- H. Ji, S.C.Prager, and J.S.Sarff, "Conservation of Magnetic Helicity during Plasma Relaxation", Phys. Rev. Lett. 74, 2945 (1995). (Abstract) (pdf file)
- M.R. Stoneking et al., "Particle Transport due to Magnetic Fluctuations", Phys. Rev. Lett. 73, 549 (1994). (pdf file)
- J.S. Sarff, S.A. Hokin, H. Ji, S.C.Prager, and C.R. Sovinec, "Fluctuation and Transport Reduction in a Reversed Field Pinch by Inductive Poloidal Current Drive", Phys. Rev. Lett. 72, 3670 (1994). (pdf file)
Concept innovation for magnetically confined fusion plasmas in the proposed SPIRIT (Self-organized Plasmas with Induction, Reconnection, and Injection Techniques): Field Reversed Configuration (FRC) plasmas formed by counter-helicity merging of spheromaks and low-aspect-ratio Reversed Field Pinch (RFP) plasmas formed by co-helicity merging of spheromaks. Selected Publications:
- S. Gerhardt, E. Belova, M. Yamada, H. Ji, Y. Ren, B. McGeehan, M. Inomoto, "Field-reversed configuration formation scheme utilizing a spheromak and solenoid induction", Physics of Plasmas 15, 032503 (2008). (pdf)
- S. Gerhardt, E. Belova, M. Yamada, H. Ji, M. Inomoto, Y. Ren, B. McGeehan, "New method for inductively forming an oblate field reversed configuration from a spheromak". Nuclear Fusion 48, 032001 (2008). (pdf)
- S. Gerhardt, E. Belova, M. Yamada, H. Ji, M. Inomoto, C, Jacobson, R. Maqueda, B. McGeehan, Y. Ren, "Inductive sustainment of oblate field-reversed configurations with the assistance of magnetic diffusion, shaping, and finite-Larmor radius stabilization", Physics of Plasmas 15, 022503 (2008). (pdf)
- S. Gerhardt, E. Belova, M. Yamada, H. Ji, M. Inomoto, R. Ren, B. McGeehan, "Inductive Sustainment of a Field-Reversed Configuration Stabilized by Shaping, Magnetic Diffusion, and Finite-Larmor-Radius Effects", Physical Review Letters 99, 245003 (2007). (pdf)
- M. Yamada, H. Ji, S. Gerhardt, E. Belova, R. Davidson, D. Mikkelsen, "A Self-Organize Plasma with Induction, Reconnection, and Injection Techniques: the SPIRIT Concept for Field Reversed Configuration Research", Plasma Fusion Res. 2, 004 (2007). (pdf)
- S. P. Gerhardt, E. Belova, M. Inomoto, M. Yamada, H. Ji, Y. Ren, and A. Kuritsyn, "Equilibrium and stability studies of oblate field-reversed configurations in the Magnetic Reconnection Experiment", Phys. Plasmas 13, 112508 (2006) (pdf file)
- H. Ji, E. Belova, S. P. Gerhardt, and M. Yamada, "Recent Advances in the SPIRIT (Self-organized Plasma with Induction, Reconnection, and Injection Techniques) Concept", J. Fusion Energy (2006)( pdf file)
- Elena V. Belova, Ronald C. Davidson, Hantao Ji, and Masaaki Yamada, "Advances in the numerical modeling of field-reversed configurations", Phys. Plasmas 13, 056115 (2006).
- E.V. Belova, R.C. Davidson, H. Ji, M. Yamada, C.D. Cothran, M.R. Brown and M.J. Schaffer, "Numerical study of the formation, ion spin-up and nonlinear stability properties of field-reversed configurations", Nucl. Fusion 46, 162-170 (2006).
- E. Belova, R. Davidson, H. Ji, and M. Yamada, "Kinetic effects on the stability properties of field-reversed configurations. II. Nonlinear evolution", Phys. Plasmas 11, 2523(2004).
- E. Belova, R. Davidson, H. Ji, and M. Yamada, "Kinetic effects on the stability properties of field-reversed configurations. I. Linear stability", Phys. Plasmas 10, 2361(2003).
- E. Belova, S. Jardin, H. Ji, M. Yamada, and R. Kulsrud, "Numerical study of global stability of oblate field-reversed configurations", Phys. Plasmas 8, 1267(2001). (Abstract) (pdf file)
- E. Belova, S. Jardin, H. Ji, M. Yamada, and R. Kulsrud, "Numerical study of tilt stability of prolate field-reversed configurations", Phys. Plasmas 7, 4996(2000). (Abstract) (pdf file)
- A. B. Hassam, R. M. Kulsrud, R. J. Goldston, H. Ji, and M. Yamada, "Steady State Thermoelectric Field-Reversed Configurations", Phys. Rev. Lett. 83, 2969(1999). (Abstract) (pdf file)
- H. Ji et al., "Studies of Global Stability of Field-reversed Configuration Plasmas Using a Rigid Body Model", Phys. Plasmas 5, 3685(1998). (Abstract) (pdf file)
3D helical divertor design in the Large helical device (LHD), the world's largest stellarator being built at the National Institute for Fusion Science, Japan. Selected publications:
- N. Ohyabu, N. Noda, H. Ji et al., "Helical Divertor in the Large Helical Device", J. Nucl. Mater. 196-198, 276 (1992).
- O. Motojima et al., "Physics and Engineering Design Studies on the Large Helical Device", Fusion Eng. Design 20, 3 (1993).
- N. Ohyabu, T. Watanabe, H. Ji et al., "The Large Helical Device (LHD) Helical Divertor", Nucl. Fusion 34, 387 (1994).
Fluctuation driven transport, dynamo measurements, and anomalous ion heating in the Reversed Field Pinch University of Tokyo Experiment (REPUTE-1), a small-to-medium-sized, toroidal reversed field pinch (RFP) device at the University of Tokyo, Japan. Selected publications:
- H. Ji, H. Toyama, K. Miyamoto, S. Shinohara, and A. Fujisawa, "Fluctuation and Electron-Heat Transport in a Reversed-Field-Pinch Plasma", Phys. Rev. Lett. 67, 62 (1991). (Abstract) (pdf file)
- H. Ji, H. Toyama, A. Fujisawa, S. Shinohara, and K. Miyamoto, "Fluctuation and Edge Current Sustainment in a Reversed-Field-Pinch", Phys. Rev. Lett. 69, 616 (1992). (Abstract) (pdf file)
- A. Fujisawa, H. Ji et al., "Anomalous Ion Temperature and Plasma Resistance due to MHD Fluctuation in REPUTE-1 RFP Plasma", Nucl. Fusion 31, 1443 (1991).