Thermal bremsstrahlung from inhomogeneous plasma

The microwave emission from a stationary plasma column having n = 10 14 cm -3 and T e ≈ 10 4 °K has been measured and interpreted taking into account the spatial distribution of the plasma density. An interference spectrometer with an indium antimonide detector was used in the wavelength range between λ = 5 mm and λ = 0.5 mm. Two kinds of spectra are discussed, those representing a black-body region at ω p and those with a smaller intensity. A satisfactory agreement is found between theory and experiment for spectra presenting a blackbody region while a discrepancy occurs around ω p for spectra never attaining the black-body value.