TY - JOUR

T1 - Drift-kinetic PIC model for simulations of longitudinal plasma confinement in mirror traps

AU - Glinskiy, V. V.

AU - Timofeev, I. V.

AU - Prikhodko, V. V.

PY - 2026

Y1 - 2026

N2 - The paper presents a 1D2V electrostatic particle-in-cell (PIC) model with a drift-kinetic description of all particle types, aiming to simulate classical longitudinal plasma transport in axially symmetric open traps. The model generalizes the semi-implicit PIC method with exact conservation of energy and charge to the case of collisional plasma and adapts it to boundary conditions on perfectly conducting walls with a floating potential. The implementation of Coulomb collisions is tested on the problem of temperature relaxation in a two-component plasma and demonstrates good agreement with the analytical theory. Since the quasi-neutral approximation is not assumed and Ampère's law is used to find the electric field, the model is able to correctly reproduce the ambipolar electric potential profile up to the walls. At the same time, the main advantage of implicit PIC simulations—the ability to use large grid steps, many times larger than the Debye radius—does not prevent the key elements of the Debye sheath physics from being reproduced correctly. In particular, the magnitude of the near-wall drop in electric potential as well as the Bohm criterion are found to be independent of whether the Debye scale is resolved or not. A comparison of stationary plasma profiles formed in a mirror trap in the presence of a constant particle source with similar profiles from the hybrid (fluid electrons) code MIDAS showed that the electron temperature, potential, and density of the confined plasma may differ by a noticeable amount, up to 15%–20%.

AB - The paper presents a 1D2V electrostatic particle-in-cell (PIC) model with a drift-kinetic description of all particle types, aiming to simulate classical longitudinal plasma transport in axially symmetric open traps. The model generalizes the semi-implicit PIC method with exact conservation of energy and charge to the case of collisional plasma and adapts it to boundary conditions on perfectly conducting walls with a floating potential. The implementation of Coulomb collisions is tested on the problem of temperature relaxation in a two-component plasma and demonstrates good agreement with the analytical theory. Since the quasi-neutral approximation is not assumed and Ampère's law is used to find the electric field, the model is able to correctly reproduce the ambipolar electric potential profile up to the walls. At the same time, the main advantage of implicit PIC simulations—the ability to use large grid steps, many times larger than the Debye radius—does not prevent the key elements of the Debye sheath physics from being reproduced correctly. In particular, the magnitude of the near-wall drop in electric potential as well as the Bohm criterion are found to be independent of whether the Debye scale is resolved or not. A comparison of stationary plasma profiles formed in a mirror trap in the presence of a constant particle source with similar profiles from the hybrid (fluid electrons) code MIDAS showed that the electron temperature, potential, and density of the confined plasma may differ by a noticeable amount, up to 15%–20%.

UR - https://www.scopus.com/pages/publications/105053425020

UR - https://www.mendeley.com/catalogue/7ca92de5-c79d-3870-a608-d52455a48770/

U2 - 10.1063/5.0326120

DO - 10.1063/5.0326120

M3 - Article

VL - 33

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 10

ER -