Theory and simulations of electrostatic field error transport

摘要

Asymmetries in applied electromagnetic fields cause plasma loss (or compression) in stellarators, tokamaks, and non-neutral plasmas. Here, this transport is studied using idealized simulations that follow guiding centers in given fields, neglecting collective effects on the plasma evolution, but including collisions at rate nu. For simplicity the magnetic field is assumed to be uniform; transport is due to asymmetries in applied electrostatic fields. Also, the Fokker-Planck equation describing the particle distribution is solved, and the predicted transport is found to agree with the simulations. Banana, plateau, and fluid regimes are identified and observed in the simulations. When separate trapped particle populations are created by application of an axisymmetric squeeze potential, enhanced transport regimes are observed, scaling as root nu when nu