Non-modal stability analysis and transient growth in a magnetized Vlasov plasma

TL;DR

This paper uses a kinetic approach to analyze the stability of collisionless magnetized plasmas, revealing transient growth phenomena and non-normal operator effects that precede Landau damping.

Contribution

It is the first to demonstrate local transient growth in a collisionless Vlasov plasma using non-modal stability theory.

Findings

Identification of transient growth before Landau damping.

Dependence of instability on magnetic field and perturbation parameters.

Time scales of instabilities are several plasma periods.

Abstract

Collisionless plasmas, such as those encountered in tokamaks, exhibit a rich variety of instabilities. The physical origin, triggering mechanisms and fundamental understanding of many plasma instabilities, however, are still open problems. We investigate the stability properties of a collisionless Vlasov plasma in a stationary homogeneous magnetic field. We narrow the scope of our investigation to the case of Maxwellian plasma. For the first time using a fully kinetic approach we show the emergence of the local instability, a transient growth, followed by classical Landau damping in a stable magnetized plasma. We show that the linearized Vlasov operator is non-normal leading to the algebraic growth of the perturbations using non-modal stability theory. The typical time scales of the obtained instabilities are of the order of several plasma periods. The first-order distribution function and the corresponding electric field are calculated and the dependence on the magnetic field and perturbation parameters is studied. Our results offer a new scenario of the emergence and development of plasma instabilities on the kinetic scale.