Spatially Resolved Measurements of Metastable Atom Density and Electric Field Strength in a Microhollow Cathode Helium Plasma by Laser Absorption Spectroscopy

抄録

We apply laser absorption spectroscopy to direct-current hollow-cathode helium plasma generated in a 0.3-mm-diameter cylindrical hole at gas pressures of 10 - 80 kPa. The measured transitions are 2³S-2³P and 2¹P-3¹D. We evaluate the helium metastable 2³S density and gas temperature using the former transition and the 2¹Patom density and electric field strength from the latter one. The observed lateral distributions of the 2³S and 2¹P atom densities depend on the gas pressure, which results from the sheath length estimated based on the spatial distribution of the evaluated electric field strength.