Gyrokinetic stability theory of electronpositron plasmas
Abstract
> The linear gyrokinetic stability properties of magnetically confined electronpositron plasmas are investigated in the parameter regime most likely to be relevant for the first laboratory experiments involving such plasmas, where the density is small enough that collisions can be ignored and the Debye length substantially exceeds the gyroradius. Although the plasma beta is very small, electromagnetic effects are retained, but magnetic compressibility can be neglected. The work of a previous publication (Helander, Phys. Rev. Lett., vol. 113, 2014a, 135003) is thus extended to include electromagnetic instabilities, which are of importance in closedfieldline configurations, where such instabilities can occur at arbitrarily low pressure. It is found that gyrokinetic instabilities are completely absent if the magnetic field is homogeneous: any instability must involve magnetic curvature or shear. Furthermore, in dipole magnetic fields, the stability threshold for interchange modes with wavelengths exceeding the Debye radius coincides with that in ideal magnetohydrodynamics. Above this threshold, the quasilinear particle flux is directed inward if the temperature gradient is sufficiently large, leading to spontaneous peaking of the density profile.
 Publication:

Journal of Plasma Physics
 Pub Date:
 June 2016
 DOI:
 10.1017/S0022377816000490
 arXiv:
 arXiv:1606.04656
 Bibcode:
 2016JPlPh..82c9001H
 Keywords:

 Physics  Plasma Physics
 EPrint:
 Journal of Plasma Physics, Volume 82, Issue 03, June 2016, 905820301