Spectrographic temperature measurement of a breakdown arc within the rimfire gas switch

Abstract

A procedure for obtaining the temperature of optically thick plasma is described. The plasma is in the form of a gas breakdown arc which conducts approximately 10-kJ of energy in 1-[mu]s. A spectrographic analysis of the trigger-section of the 6-MV RIMFIRE laser triggered gas switch used in Sandia National Laboratory's "Z-Machine" has been completed. It is assumed that the breakdown plasma has achieved approximate local thermodynamic equilibrium allowing a black-body temperature model to be applied. This model allows the plasma temperature and radiated power to be approximated. The gas dielectric used in these tests was pressurized SF6. The electrode and the insulator materials are stainless steel and PMMA, respectively. A spectrum range from 250 to 450 nanometers has been observed and calibrated using two spectral irradiance lamps and three spectrograph gratings. The approximate plasma temperature and radiated power are reported.