Stetson, Robert F.

An experimental investigation of a reflex
discharge in Argon is carried out. Definition is
made of a region of acceptable operating parameters
consistent with continuous, stable operation of
the plasma. Electron temperature is measured through the
use of spectroscopy, electrostatic wave propagation,
and Langmuir Probes. An electron temperature in the
1 eV to 5 eV range is indicated. Electron density
is measured through the observation of the upperhybrid
frequency. This observation yields an electron
density in the region from .27 x 10^8/cm^3 to 2.38 x 10^8/cm^3. The microwave apparatus used in the density measurement
is described in detail.

Emission of radiation from an argon and helium plasma perpendicular
to the applied magnetic field in the x-band is discussed. Microwave
emission was observed when the cyclotron frequency at the center of the
plasma was above the mixer frequency of the radiometer, and at what
appears to be multiples of the cyclotron frequency. An explanation of
the microwave emission based on the solution of the Boltzmann equation
assuming electron-neutral collisions is discussed. The temperature and
density of the plasma were determined from probe and spectroscopic
experiments. Temperatures in the range of 4 to 16 eV were measured and
probe data indicated a plasma density from (0.5 - 3) x 10^9 cm^-3.