Characteristic quantities of a cascade arc used as a light source for spectroscopic techniques

The authors have determined the characteristic quantities (the electron temperature and the electron density) of an argon plasma in a cascade arc (diameter of 2 and 4 mm) for a pressure range of 1*10 5 -8*10 5 Pa and a current range of 20-70 A. The absolute continuum intensity was also determined in the wavelength ranges from 250-320 nm and 380-800 nm for pressures of 2, 4 and 6 bar and 20, 40 and 60 A in the case of a 2 mm arc. The plasma is close to local thermal equilibrium (LTE). Using the mentioned quantities, prediction of the absolute intensity as a function of the wavelength is possible from 140 nm to the infrared within 10%. The use of the arc as a light source in photon induced chemical vapour deposition, spectroscopic ellipsometry and infrared absorption spectroscopy is discussed.