Characteristics of Two Types of Grazing Incidence Spectrometers with Holographic Gratings

Abstract

Two types of grazing incidence spectrometers have been constructed which are applicable to photographic and photo-electric recordings of emission spectra of plasmas in the extreme ultraviolet. The spectrometer SGX-100 with a 1-m Rowland circle covers the wavelengths of 30 to 1500 Å with both a holographic grating (HG) and a ruled one (RG). In this spectrometer, the incidence angle cc to the gratings is continuously variable from 80°to 86°, where the inverse Vodar mounting is adopted to keep a constant line of sight of the spectrometer against a light source. The small grazing incidence spectrometer GIT-30 with a toroidal holographic grating covers the wave-lengths of 150 to 1600 Å. The wavelength scanning is performed by a simple rotation of the grating under a constant angle 142° between the incident and exit beams. These spectrometers were used to observe spectra of emissions from a hollow cathode lamp and linear Z-pinch and plasma-focus discharges. Characteristics of the spectrometers are discussed on the data observed.