APPARATUS FOR GENERATING ULTRAVIOLET RADIATION OF HIGH SPECTRAL RADIANCE

摘要

Apparatus for generating ultraviolet radiation of high spectral radiance whereby the radiation is produced in a discharge tube having a thermoemissive cathode and a discharge space and filled with mercury/argon by means of a wall-stabilized direct-current gas discharge at a mercury pressure pHg of between 5 x 10<->3 and 5 x 10<->1 Torr and a current density j of the discharge current I of between 1 and 25 A/cm2. The discharge tube incorporates a pressure-equalizing space connecting the cathode space to the anode space whereby the sum of the volumes of the cathode space, anode space and pressure-equalizing space is greater than the volume of the discharge space. The pressure of the argon is maintained between 0.01 and 10 Torr. A first control element is provided which regulates the current density j of the discharge current I to a constant value jO between 1 and 25 A/cm2. A second control element is provided which regulates the pressure pHg of the mercury to such a value that the yield eta of the line of wavelength 2537 A, i.e. the ratio of the spectral radiation power for the wavelength lambda = 2537 A to the electrical power stored in the discharge, is at least 80% of the maximum yield eta max for the chosen current density jO.