Page 7 - Electrostatic quasi-neutral formulation of global cross-separatrix particle simulation in field-reversed configuration geometry

Physics of Plasmas ARTICLE
FIG. 2. Analytic theory (dashed line) of the drift-wave is plotted on top of spectral power found from ANC simulation using three different models: (a) gyrokinetic ions with drift- kinetic electrons, (b) gyrokinetic ions with an adiabatic electron response, and (c) blended ions with an adiabatic electron response. The simulation results are consistent with theory, tracking along the drift-wave frequency which is shifted away from zero. At shorter wavelengths (for example, in the blended case (c), jkk qi j > 4:2 􏰅 10􏰁5 ), simulation deviates from theory due to the lower numerical resolution as well as numerical smoothing which was used in this simulation.
FIG. 3. Analytic theory (dashed line) of the ion acoustic wave is plotted on top of spectral power found from ANC simulation. The simulation results are consistent with theory, tracking along the correct slope of the ion acoustic wave.
uniform magnetic field; and (4) the assumption of kk 􏰈 0 􏰇 k?, the dispersion of the so-called neutralized Ion Bernstein mode18 is
n 2 X 2 c ; i
KnðbÞx2􏰁n2X2 ; (37)
c;i
where KnðbÞ􏰂InðbÞexpð􏰁bÞ is the exponentially scaled modified
22
Bessel function of the first kind and b 􏰂 k?qi . In the simulation, the
electron response is explicitly set to be adiabatic while the ions use the blended particle model. Although only the component with kk 1⁄4 0 is kept, the adiabatic electron response assumption is consistent between the shown dispersion relation and within this simulation. This bench- mark is designed to show the fully kinetic physics capability of the blended model in the perpendicular direction whereas the previous gyrokinetic model would not include such physics.
In Fig. 4, the numerical solution of the analytic theory (37) is plotted as dashed lines, while the normalized 2D spectral power shows the ANC simulation. While the higher frequency branches are cap- tured by the simulation, the resolution used only roughly resolves the
27, 082504-7
01⁄41􏰁2T
i n1⁄41
T e X1
scitation.org/journal/php
Phys. Plasmas 27, 082504 (2020); doi: 10.1063/5.0012439 Published under license by AIP Publishing