TY - JOUR

T1 - The role of electron current in high-β plasma equilibria

AU - Kurshakov, V. A.

AU - Timofeev, I. V.

N1 - This work is supported by the Russian Science Foundation (Grant No. 21‐72-10071). The authors thank E.A. Berendeev and I.A. Kotelnikov for useful discussions.

PY - 2023/9/1

Y1 - 2023/9/1

N2 - This paper is aimed at investigating the role of electrons in creation of currents in plasma equilibria with high plasma pressure ( β ≈ 1 ). Despite the long history of studies of these equilibria, there is still no consensus on what kind of particle species is responsible for the creation of the diamagnetic current and what characteristic size the current layer should have. For example, simulations of isothermal plasma injection into a multi-cusp magnetic trap [J. Park et al., Front. Astron. Space Sci. 6, 74 (2019)] demonstrate the formation of a transition layer with a thickness comparable to the electron Larmor radius, where the equilibrium current is carried by electrons. At the same time, studies of a diamagnetic bubble created by a hot-ion plasma in a mirror trap [I. Kotelnikov, Plasma Phys. Control Fusion 62, 075002 (2020)] assume ion dominance and completely ignore electron currents. In this paper, we show that the equilibrium initially governed by the ion diamagnetic current is unstable against perturbations at the ion-cyclotron frequency harmonics, and this instability forces the plasma to come to a new equilibrium state in which the current is mainly created by the E × B -drift of electrons. The same type of equilibrium is also found to form in a more realistic problem setup when plasma is continuously injected into the uniform vacuum magnetic field.

AB - This paper is aimed at investigating the role of electrons in creation of currents in plasma equilibria with high plasma pressure ( β ≈ 1 ). Despite the long history of studies of these equilibria, there is still no consensus on what kind of particle species is responsible for the creation of the diamagnetic current and what characteristic size the current layer should have. For example, simulations of isothermal plasma injection into a multi-cusp magnetic trap [J. Park et al., Front. Astron. Space Sci. 6, 74 (2019)] demonstrate the formation of a transition layer with a thickness comparable to the electron Larmor radius, where the equilibrium current is carried by electrons. At the same time, studies of a diamagnetic bubble created by a hot-ion plasma in a mirror trap [I. Kotelnikov, Plasma Phys. Control Fusion 62, 075002 (2020)] assume ion dominance and completely ignore electron currents. In this paper, we show that the equilibrium initially governed by the ion diamagnetic current is unstable against perturbations at the ion-cyclotron frequency harmonics, and this instability forces the plasma to come to a new equilibrium state in which the current is mainly created by the E × B -drift of electrons. The same type of equilibrium is also found to form in a more realistic problem setup when plasma is continuously injected into the uniform vacuum magnetic field.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85173494895&origin=inward&txGid=809b9fe09f002f346f5a09c5fd6ee3e8

UR - https://www.mendeley.com/catalogue/08e2b135-7141-3612-af4c-03dad74535b4/

U2 - 10.1063/5.0153855

DO - 10.1063/5.0153855

M3 - Article

VL - 30

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 9

M1 - 092513

ER -