Electron density measurements in rapidly moving pulsed-power plasmas by means of a CO_(2) laser interferometer

摘要

A CO_(2) laser interferometer has been set up in order to measure electron densities in rapidly moving pulsed-power discharges. The experiment is designed to produce arc-shaped magnetic flux tubes which are topologically similar to ascending solar protuberances. The minor radius of the flux tube is about 2-3 cm while its major radius starts from 4 cm and expands with a velocity of roughly 1-3 cm (mu)s~(-1). Preliminary investigations by means of an electrostatic triple probe indicate that the electron density of the plasma is around 10~(21) m~(-3). Electron temperatures are roughly 10 eV. By letting the discharge arc pass the probing beam of the interferometer, spatially resolved density measurements are possible. Application of fast detection systems allows even the resolution of small structures within the discharge arc.