Cylindrical plasmas generated by an annular beam of ultraviolet light

TL;DR

This paper studies a cylindrical plasma created by an ultraviolet light beam, revealing a steady-state configuration with a uniform, field-free inner plasma and potential for laboratory applications.

Contribution

It introduces a novel model of a cylindrical plasma system with ionization confined to an outer annular region, enabling the creation of uniform stationary plasmas in the lab.

Findings

Inner plasma is uniform and field-free.

A sharp ion density interface exists at the boundary.

Potential for laboratory production of uniform plasmas.

Abstract

We investigate a cylindrical plasma system with ionization, by an annular beam of ultraviolet light, taking place only in the cylinder's outer region. In the steady state, both the outer and inner regions contain a plasma, with that in the inner region being uniform and field-free. At the interface between the two regions, there is an infinitesimal jump in ion density, the magnitude approaching zero in the quasi-neutral $(\lambda_D \rightarrow 0)$ limit. The system offers the possibility of producing a uniform stationary plasma in the laboratory, hitherto obtained only with thermally produced alkali plasmas.