Messungen am Ar-Hochdruckbogen

TheE(J)-characteristics, the radiated power, and the radial temperature distributions are measured in a 5 mm Ø Ar cascade arc in the pressure range 1–10 atms up to 590 A. The characteristics are determined by the quasistatic method, while the radiated power is recorded by a radiation thermocouple. The ratio of radiated to invested power as function of currentJ passes a maximum which rises up to 75% at 10 atms and 150 A. The temperature is evaluated from side-on registration of proper atom and ion line intensities by means of a photomultiplier. The highest axial temperature of 26000 K is achieved at atmospheric pressure; at higher pressures, the axial temperature falls. In order to investigate the frequency dependence of the continuum emission coefficient the spectral intensity of the continuum is measured at several wavelengths between 2400 and 8500 Å.