Determination of the gas kinetic temperature of a supersonic hydrogen plasma jet by using a monochromator with built-in planar Fabry-Perot interferometer

An investigation of gas kinetic temperatures in a supersonic hydrogen plasm a jet has been performed. Under the conditions used the broadening of the B almer alpha line is predominantly caused by Doppler broadening due to therm al motion. The spectral resolution needed was achieved by the insertion of a planar Fabry-Perot interferometer into the parallel optical path of a con ventional scanning 1 m focal-length Czerny-Turner monochromator. Considerin g the fine structure of the lines as well as the instrument function of the interferometer, gas kinetic temperatures were determined from the measured line shapes. Gas kinetic temperatures of the supersonic hydrogen plasma je t ranging from 1200 to 2300 K with an experimental error of +/-10% were obt ained. Temperatures obtained were weighted averages along the line of sight with a lateral resolution of about 8 mm.