Electrostatic stability of electron-positron plasmas in dipole geometry

Abstract

The electrostatic stability of electron-positron plasmas is investigated in the point-dipole and Z-pinch limits of dipole geometry. The kinetic dispersion relation for sub-bounce-frequency instabilities is derived and solved. For the zero-Debye-length case, the stability diagram is found to exhibit singular behavior. However, when the Debye length is non-zero, a fluid mode appears, which resolves the observed singularity, and also demonstrates that both the temperature and density gradients can drive instability. It is concluded that a finite Debye length is necessary to determine the stability boundaries in parameter space. Landau damping is investigated at scales sufficiently smaller than the Debye length, where instability is absent.

References in corpus (2)

• Available energy and ground states of collisionless plasmas
• Local Gyrokinetic Study of Electrostatic Microinstabilities in Dipole Plasmas

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• The gyrokinetic field invariant and electromagnetic temperature-gradient instabilities in `good-curvature' plasmas
• Predicting the Dimits shift through reduced mode tertiary instability analysis in a strongly driven gyrokinetic fluid limit