TY - JOUR

T1 - Formation of cylindrical plasma equilibria with β > 1

AU - Timofeev, I. V.

AU - Kurshakov, V. A.

AU - Berendeev, E. A.

N1 - This work was supported by the Russian Science Foundation (Grant No. 21-72-10071).

PY - 2024/8/1

Y1 - 2024/8/1

N2 - High-beta plasma equilibria are realized in a number of physical systems, from planetary magnetospheres, sunspots, and magnetic holes to fusion laboratory experiments. When plasma pressure becomes large enough to completely expel the magnetic field from its volume, the particle trajectories cannot be considered any more as circular gyro-orbits, and plasma pressure ceases to be gyrotropic. These non-gyrotropic effects require kinetic description and are actively studied for a long time in the magnetic reconnection problem. In this paper, we will show that non-gyrotropy of plasma pressure makes it possible to markedly exceed the limit β = 1 dictated by the magnetohydrodynamics for finite-size plasmas, which may be attractive for some fusion schemes such as mirror and cusp configurations. As a first step, we study how these effects manifest themselves in a simple classical problem of confining a cylindrical plasma column by a uniform vacuum magnetic field. Using particle-in-cell simulations, we show that the equilibrium of the diamagnetic bubble type with zero internal magnetic field is formed with an electron-produced current layer of sub-ion scale and found that the gas-kinetic pressure of the central plasma exceeds the pressure of the vacuum magnetic field by 15%.

AB - High-beta plasma equilibria are realized in a number of physical systems, from planetary magnetospheres, sunspots, and magnetic holes to fusion laboratory experiments. When plasma pressure becomes large enough to completely expel the magnetic field from its volume, the particle trajectories cannot be considered any more as circular gyro-orbits, and plasma pressure ceases to be gyrotropic. These non-gyrotropic effects require kinetic description and are actively studied for a long time in the magnetic reconnection problem. In this paper, we will show that non-gyrotropy of plasma pressure makes it possible to markedly exceed the limit β = 1 dictated by the magnetohydrodynamics for finite-size plasmas, which may be attractive for some fusion schemes such as mirror and cusp configurations. As a first step, we study how these effects manifest themselves in a simple classical problem of confining a cylindrical plasma column by a uniform vacuum magnetic field. Using particle-in-cell simulations, we show that the equilibrium of the diamagnetic bubble type with zero internal magnetic field is formed with an electron-produced current layer of sub-ion scale and found that the gas-kinetic pressure of the central plasma exceeds the pressure of the vacuum magnetic field by 15%.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85202017197&origin=inward&txGid=1d08487d8bc5f04b0adc3fc19a272ab3

UR - https://www.mendeley.com/catalogue/55018160-a6af-31cc-a8da-3eaec05015bb/

U2 - 10.1063/5.0216073

DO - 10.1063/5.0216073

M3 - Article

VL - 31

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 8

M1 - 082512

ER -