Emission of Sub-millimetre Electromagnetic Radiation from Hot Plasma in ZETA

Abstract

The first results are reported of experiments using a technique new to plasma research, namely spectroscopy in the far infra-red region (wavelength 0.1-1.6 mm). The shapes of the spectra obtained from zeta are consistent with the observed radiation being entirely due to free-free transitions (bremsstrahlung) and become characteristic of black-body emission at the longer wavelengths. The measured absolute values of the surface brightness of the discharge are in agreement (subject to reasonable assumptions) with the predictions of quantum theory.