Temperature measurements of fusion plasmas produced by petawatt laser-irradiated D2-3He or CD4-3He clustering gases

TL;DR

This study measures plasma temperatures in laser-induced fusion plasmas using ion time-of-flight and nuclear reaction rate ratios, finding consistent results that suggest a near-Maxwellian ion energy distribution.

Contribution

It introduces two complementary methods for accurately determining plasma temperature in laser-cluster fusion experiments, confirming the ion energy distribution is close to Maxwellian.

Findings

Both methods yield consistent temperature measurements.

Ion energy distribution remains close to Maxwellian during disassembly.

Results support the validity of using these methods for plasma diagnostics.

Abstract

Two different methods have been employed to determine the plasma temperature in a laser-cluster fusion experiment on the Texas Petawatt laser. In the first, the temperature was derived from time-of-flight data of deuterium ions ejected from exploding D2 or CD4 clusters. In the second, the temperature was measured from the ratio of the rates of two different nuclear fusion reactions occurring in the plasma at the same time: D(d, 3He)n and 3He(d, p)4He. The temperatures determined by these two methods agree well, which indicates that: i) The ion energy distribution is not significantly distorted when ions travel in the disassembling plasma; ii) The kinetic energy of deuterium ions, especially the hottest part responsible for nuclear fusion, is well described by a near-Maxwellian distribution.