pankin

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Alexei Pankin
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pankin
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Posts by pankin

New smoothing procedure for radial electric field is implemented

New procedure for smoothing of radial electric field profile is implemented in the fmcfm_call routine. Different levels of smoothing is applied in the plasma core and in the plasma edge. The radial electric field profile in the plasma edge is smoothed fm_nsmooth times together other plasma profiles such as electron and ion temperatures and plasma density profiles. The radial electric field in the plasma core is smoothed fm_nsmooth_er times. The new smoothed profiles are merge together using the following formula:

{Huge E_r} = displaystylefrac{1}{2} left[ E_r^{rm core} left( 1 - tanh(C_{er} (rho-rho_b)) ) + E_r^{rm edge} ( 1 + tanh(C_{er} (rho-rho_b)) right) right]

and used in the computation of the ExB flow shear. Here, C_{er} is the coefficient that describes sharpness of the transition between two smoothed profiles The fm_smooth_er_coef is used to set this coefficient in the XGC-0 code through the namelist. The rho_b parameter controls the location of the transition. The fm_smooth_er_rhob variable is used to set this parameter in the code. The default values for these parameters are: C_{er}=75 and rho_b=0.95.


XGC-0 simulations results for cases XGC-204 and XGC-205

GXC0 results are analyzed:

  • Case XGC-204 crashed after 65000 time steps. It is possible that time limit for this simulation has been set incorrectly.
  • Case XGC-205 crashed after 50000 time steps. Same reason (?)

Profiles for plasma density, temperatures and electric field are given below.

Radial electric field remains very noisy in the plasma core. Both the radial electric field and plasma density profiles are found to be very different comparing to the case when electron dynamics has been diabled (case XGC-203).