Präzisionsmessungen am Spektrum des Wasserstoffplasmas

Abstract

Detailed and precise investigations on the Balmer spectrum of a hydrogen arc have been made in order to compare the measured absolute values of the spectral emission coefficients with the existing theories, the results being of special interest with respect to line broadening calculations and to the lowering of the ionization energy. The plasma is generated in a stationary high power cascade arc at atmospheric pressure. The experiment covers the temperature range between 12000 and 20000 K, where all emission coefficients show maxima in their temperature dependence. To keep self-absorption within the plasma as low as possible, the investigations have been carried out in side-on observation. The extended gas layer of almost constant intensity surrounding the maxima ensures very accurate results of the side-on measurements. For the necessary precise calibration of the optical system both a standard carbon arc and tungsten strip lamps have been used. As the intensity of these different radiation standards only shows a few percent deviation, a very high accuracy can also be established for the measured hydrogen emission coefficients.