Laser Induced Fluorescence (LIF) Measurements of Neutral (ArI) and singly-ionized (ArII) Argon in a LargeScale Helicon Plasma*

In order to investigate the role of neutral dynamics in helicon discharges in the HelCat (Helicon-Cathode) plasma device at U. New Mexico, a Laser Induced Fluorescence (LIF) system has been developed. The LIF system is based on a \textgreater 250 mW, tunable diode laser with a tuning range between 680 and 700nm. For neutral Argon, the laser pumps the metastable ($^{\mathrm{2}}$P$^{\mathrm{0}}_{\mathrm{3/2}})$4s level to the ($^{\mathrm{2}}$P$^{\mathrm{0}}_{\mathrm{1/2}})$4p level using 696. 7352 nm light. The fluorescence radiation from decay to the ($^{\mathrm{2}}$P$^{\mathrm{0}}_{\mathrm{1/2}})$4s level at 772. 6333 nm is observed. For singly ionized Argon, the laser pumps the 3s$^{\mathrm{2}}$3p$^{\mathrm{4}}(^{\mathrm{3}}$P)3d level to the 3s$^{\mathrm{2}}$3p$^{\mathrm{4}}(^{\mathrm{3}}$P)4p level using 686.3162nm light. The fluorescence radiation from the decay to the 3s$^{\mathrm{2}}$3p$^{\mathrm{4}}(^{\mathrm{3}}$P)4s level is observed. The system design, and velocity measurements in the axial, azimuthal and radial directions for ArI, and in the axial direction for ArII will be presented.