Strong axial laser heating of a theta-pinch plasma

Abstract

Holographic interferograms are shown of θ‐pinch plasmas heated axially by 35 J of 10.6‐μm radiation. One hundred percent conversion of laser to plasma thermal energy is indicated by the resultant plasma expansion and inferred temperature increase from 10 to 65 eV. The heated plasma column is 10 cm long by 6 mm in diameter and at an electron density of about 5 × 10¹⁷ cm⁻³. The laser heating process is seen to produce a self‐trapping density minimum on axis in contrast to the density maximum encountered in normal unheated θ pinches. This has significant implications for the high‐density laser‐heated long‐solenoid approach to fusion.