Spectrographic analysis of the plasma arc generated within the RIMFIRE gas switch

The University of Missouri—Columbia is currently utilizing a refurbished Proto II Marx bank provided by Sandia National Laboratory to conduct pulsed power research. The Marx bank has the potential to produce a voltage of 3 MV across a gas switch, generating breakdown currents in excess of 500 kA. There is a necessary interest in the physical processes involved with the generation of a plasma arc within the RIMFIRE gas switch. The UV flux generated by the plasma is thought to be depositing charge on the walls of the plastic insulator and contributing to an unacceptably high rate of switch failure due to insulator flashover. The photons emitted by the plasma can also be useful in characterizing the switch by identifying ejected electrode materials, ionized background gases, and plasma temperatures. This characterization could be useful in the development of gas switches with shorter rise times, higher power capabilities, and reduced failure rates. A spectrographic analysis of the trigger-section of the RIMFIRE laser triggered gas switch used in Sandia National Laboratory’s “Z-Machine” has been completed. The gas dielectric used in these tests was pressurized SF6 and the electrode material is stainless steel. A spectrum range from 200 to 700 nanometers has been observed. The measured spectrum is reported.