Electron Kinetics in Plasmoids

Abstract: Plasmoids are localised regions of high plasma density that

arise in both MCF and astrophysical contexts. Owing to the higher

thermal mobility of electrons relative to ions, a plasmoid is associated

with a localised electric potential that acts to trap electrons. This elec-

tric potential also acts to push ions away from the centre of the plas-

moid, causing it to expand. As the well expands, energy is extracted

adiabatically from trapped electrons – this is the source of energy for

the ion flow velocity acquired during expansion. An understanding

of electron kinetics in plasmoids is therefore critical in developing an

understanding of plasmoid dynamics. Two frameworks for electron ki-

netics in plasmoid are presented. In the first framework, the electron distribution is 

assumed to be isotropic and the electron kinetic equation, including the full nonlinear Landau

self-collision operator, is integrated exactly over bounce motion and

pitch-angle, resulting in a 1D+time equation, the spacial variable be-

ing a novel adiabatic invariant.