Key Parameter Measurements of the Low-Pressure Gas Discharge Plasmas Used for Studying the Ion Extraction Process

Abstract

Extraction of the target isotope ions in the laser photoionized plasmas is one of the key processes in the atomic vapor laser isotope separation. The key plasma parameters, including the electron number density, the temperatures of electrons and heavy species, may have significant influences on the characteristics of the ion extraction process. In recent years, the ion extraction simulation facility has become an important tool to study the ion extraction mechanisms. In the present paper, a low-pressure, alternating-current (AC) gas discharge experimental setup is developed. Based on this gas discharge plasma source, the electrical and optical measurements are conducted for studying the features of the argon discharge plasma jet under different operating conditions. In particularly, a collisional-radiative model is established for argon plasmas and is used for the derivation of the electron temperature and number density based on the measured spectral line-intensity ratios, while the gas temperature is obtained by fitting the recorded optical emission spectra of the plasma jet ranging from 334.5 to 337.5 nm using SPECAIR. The preliminary experimental results show that both the power input and driving frequency of the power supplies have significant influences on the number density and temperature of electrons in the expanded plasma jet region with constant chamber pressures of (6.0–9.0) × 10−2 Pa. The measured key plasma parameters, including the temperature and number density of electrons and the gas temperature, of the argon plasma jet are, on the order of magnitude, close to those of the laser photoionized plasmas in the laser isotope separation process, which provides a good basis for the ion extraction simulation experiments.