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.