Spectroscopic measurement of high current vacuum arc plasma in triggered vacuum switch

The purpose of this experiment is to improve understanding of the high current vacuum arc phenomena in a triggered vacuum switch (TVS). The TVS used in the experiment has a rod array electrode. The cross section of each rod has trapezoidal shape. A spectroscopic measurement was performed up to 150 kA peak current at the center of electrodes. The tested electrode material was Fe. Measured Fe spectrum range was from 200 nm to 900 nm. Measurement result showed that over 90 percent of the charge states were Fe II, and the others were Fe I and Fe III. By assuming a local thermal equilibrium (LTE), electron temperatures of the TVS arc were determined from the relative line intensity ratio of Fe II. The electron temperatures at the center of electrodes were measured as 1.5 eV and 2.5 eV with 26 kA and 64 kA peak currents, respectively. The electron temperature increased with its peak current.