A visible plasma

Abstract

Summary form only. The authors have obtained a steady-state plasma with the plasma frequency in the visible. Thus, in principle, phenomena such as the production of electron plasma oscillations can be observed visually. The authors have shown that metallic cesium has both a very low value of free electron density, n, due to its bloated atomic size, and a large number of bound electrons (54) that are polarizable and increase the value of permittivity, ε, to 1.4165 ε0, where ε0 is the permittivity of vacuum. The low value of electron density alone results in a plasma frequency corresponding to ultraviolet light at 3630 Å, but adding in the correction to ε0 results in a wavelength of 4320 Å, which is in the blue. The authors have succeeded in photographing the blue light penetrating above the cutoff at the plasma frequency