Quasi-stationary States of Two-Dimensional Electron Plasma Trapped in Magnetic Field

TL;DR

This study uses numerical simulations to explore the evolution of two-dimensional electron plasma in a magnetic field, revealing how initial conditions influence the resulting quasi-stationary states and their relation to statistical theories.

Contribution

It demonstrates the dependence of quasi-stationary states on initial conditions and compares simulation results with various statistical theories.

Findings

Vortex crystal states form from thinner-ring initial states.

Single-peaked density states emerge from thicker-ring initial states.

Quasi-stationary states are not ergodic and depend on initial conditions.

Abstract

We have performed numerical simulations on a pure electron plasma system under a strong magnetic field, in order to examine quasi-stationary states that the system eventually evolves into. We use ring states as the initial states, changing the width, and find that the system evolves into a vortex crystal state from a thinner-ring state while a state with a single-peaked density distribution is obtained from a thicker-ring initial state. For those quasi-stationary states, density distribution and macroscopic observables are defined on the basis of a coarse-grained density field. We compare our results with experiments and some statistical theories, which include the Gibbs-Boltzmann statistics, Tsallis statistics, the fluid entropy theory, and the minimum enstrophy state. From some of those initial states, we obtain the quasi-stationary states which are close to the minimum enstrophy state, but we also find that the quasi-stationary states depend upon initial states, even if the initial states have the same energy and angular momentum, which means the ergodicity does not hold.