Collisionsless amplifying of longitudinal electron waves in two-stream plasma

TL;DR

This paper investigates collisionless amplification of longitudinal electron waves in two-stream plasmas using simplified models, revealing conditions for wave growth and damping without complex integrals, with potential practical applications.

Contribution

It introduces a simplified algebraic approach to analyze wave amplification in two-stream plasmas, avoiding complex integrals and providing insights into wave growth mechanisms.

Findings

Identification of non-damping forward waves

Discovery of exponentially damping and growing waves

Simplified algebraic dispersion relation

Abstract

To better understanding the principal features of collisionless damping/growing plasma waves we have implemented a demonstrative calculation for the simplest cases of electron waves in two-stream plasmas with the delta-function type electron velocity distribution function of each of the streams with velocities v(1) and v(2). The traditional dispersion equation is reduced to an algebraic 4th order equation, for which numerical solutions are presented for a variant of equal stream densities. In the case of uniform half-infinite slab one finds two dominant type solutions: non-damping forward waves and forward complex conjugated exponentially both damping and growing waves. Beside it in this case there is no necessity of calculation any logarithmically divergent indefinite integrals. The possibility of wave amplifying might be useful in practical applications.