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arXiv · 2606.27253

Ion firehose and ion cyclotron instability with subtracted-Kappa distributions

Luiz F. Ziebell·Rudi Gaelzer·Danny Summers
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Abstract

In the present paper we discuss numerical solutions of the dispersion relation for electromagnetic waves propagating along the lines of an ambient magnetic field, considering parameters representative of space plasma environments, and considering the ion population described by a subtracted-Kappa distribution. We consider situations in which the ion thermal anisotropy is such that $T_{i\perp} T_{i\parallel}$, and investigate the effects of the same parameters on the ion-cyclotron instability. For both forms of instability, we also investigate the effect of the thermal anisotropy of the electron distribution, and the effect of the occurrence of a drift velocity in the electron distribution function. Among the results obtained, we show that the increase of the loss-cone feature in a bi-kappa distribution leads to a decrease of the growth rates of the firehose instability, and to an increase of the growth rates of the ion-cyclotron instability.

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Luiz F. Ziebell, Rudi Gaelzer, Danny Summers. 2026-06-25. Ion firehose and ion cyclotron instability with subtracted-Kappa distributions. https://arxiv.org/abs/2606.27253

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