Low Pressure High Density Plasma Diagnostics Development of on the Helicon Plasma Experiment (HPX)

The small Helicon Plasma Experiment (HPX) at the Coast Guard Academy Plasma Lab (CGAPL), continues to progress toward utilizing the reputed high densities (10¹³ cm^-3 and higher) at low pressure (.01 T) of helicons, for eventual high temperature and density diagnostic development in future laboratory investigations. HPX has installed an Impedans Langmuir probe and constructed an RF-shielded triple probe diagnostic to compare the plasma perameters and behavior during experiments. Our 2.5 J YAG laser Thomson Scattering system operates at its first and second harmonics, 532 and 1064 nm respectively. It utilizes a volume-phase-holographic (VPH) grating spectrometer, a CCD camera with a range of 380-1090 nm for second harmonic (532 nm) photon emissions. At 1064 nm, a new polychromator has been procured from General Atomics optimized for TS measurements of 5 eV < T_e < 2000 eV over a 109-degree scattering angle. HPX diagnostics are backed by our Data Acquisition (DAQ) system is capable 12 bits of sampling precision at 2 MS/s. Progress on the construction of the Helicon Mode development, Thomson Scattering, plus particle and electromagnetic diagnostic observations will be reported.

1 K. Toki, et al., Thin Solid Films 506-507 (2005)