PROPERTIES OF RELATIVELY-DILUTE PLASMAS IN PULSED-POWER SYSTEMS OBTAINED FROM HIGH-ACCURACY LASER SPECTROSCOPY

摘要

We describe a novel application of laser-spectroscopy to investigate the electric fields and the properties of relatively dilute plasmas under high-power pulses at the nanosecond time scale. The method is based on resonant laser-pumping combined with electron excitations and de-excitations by the plasma electrons, which allows for simultaneous observations of various line intensities (due to both allowed and forbidden transitions). These observations, together with novel line-shape calculations recently developed, allow for obtaining the electron density, electron temperature, and electric fields. Another feature of the method developed is that plasma-doping is incorporated, which, combined with the laser spectroscopy, yields 3D-spatially-resolved (sub-mm) measurements. The study is carried out in a coaxial-pulsed-plasma configuration (a Plasma Opening Switch). For the first time, line-shape diagnostics was successfully applied to determine the properties of plasmas with densities down to 10{sup}13 cm{sup}(-3) at a sub-microsecond time scale. The electron density was determined rather accurately even though the line profiles were dominated by the instrumental and Doppler broadenings. Such diagnostics can be used for the investigation of high-current carrying plasmas formed in High-Power Transmission Lines, Plasma Switches, Ion and Electron Diodes, and Plasma Sources.