Use of Optical Spectra to Measure Large Electric Fields in a Hot-Ion Plasma

Abstract

Intense electric fields found in the beam‐plasma interface of Burnout V give rise to satellite spectra of the helium 2³P‐4³D, ³F triplet (4471 Å), and the 2¹P‐4¹D, ¹F singlet (4922 Å) emission lines. Electric‐field strengths increasing from near zero on the magnetic axis to about 7 kV cm⁻¹ at 1 cm, and then decreasing to less than 2 kV cm⁻¹ at 2‐cm radial distance are found. An Abel inversion giving intensity of the satellite lines as a function of plasma radius together with displacement and intensity of π and σ components in the Zeeman structure of the satellites gives the electric‐field strength and implies that the direction of the electric field is perpendicular to the magnetic axis.