Open AccessNumerical Study of Field-reversed Configurations: The Formation and Ion Spin-up
Author(s) -
Е. В. Белова,
Ronald C. Davidson,
Hantao Ji,
Masaaki Yamada,
C. D. Cothran,
M. R. Brown,
M. J. Schaffer
Publication year - 2005
Language(s) - English
Resource type - Reports
DOI - 10.2172/840784
Subject(s) - magnetohydrodynamics , physics , helicity , toroid , magnetohydrodynamic drive , spheromak , atomic physics , instability , ion , mechanics , plasma , nuclear physics , particle physics , quantum mechanics
Results of three-dimensional numerical simulations of field-reversed configurations (FRCs) are presented. Emphasis of this work is on the nonlinear evolution of magnetohydrodynamic (MHD) instabilities in kinetic FRCs, and the new FRC formation method by counter-helicity spheromak merging. Kinetic simulations show nonlinear saturation of the n = 1 tilt mode, where n is the toroidal mode number. The n = 2 and n = 3 rotational modes are observed to grow during the nonlinear phase of the tilt instability due to the ion spin-up in the toroidal direction. The ion toroidal spin-up is shown to be related to the resistive decay of the internal flux, and the resulting loss of particle confinement. Three-dimensional MHD simulations of counter-helicity spheromak merging and FRC formation show good qualitative agreement with results from the SSX-FRC experiment. The simulations show formation of an FRC in about 20-30 Alfven times for typical experimental parameters. The growth rate of the n = 1 tilt mode is shown to be significantly reduced compared to the MHD growth rate due to the large plasma viscosity and field-line-tying effects