Absolute x-ray calibration of laser-produced plasmas using a CCD linear array and a focusing crystal spectrometer

Abstract

ABSTRACT Absolute x-ray calibration of laser-produced plasmas was performed using a CCD linear array and a focusing crystalspectrometer. The plasmas were created by a Nd glass laser (0.53 im/1O J/2 ns) and a high repetition rate Nd-YAG laser(0.53 jtm/2OO mJ/3 ns/lO Hz). A commercial CCD (Toshiba model TCD 1304AP) was used for x-ray detection. TheCCD linear array has 3724 pixels (8 jtm width and 200 pm height) giving a total length of -3O mm. First the CCDdetector was absolutely calibrated using laser-produced plasmas and an Fe55 isotope source. The sensitivity of thedetector was about two orders of magnitude higher than x-ray photographic film (Kodak RAR 2492). The CCD detectorwas used for monitoring the absolute x-ray yield, for finding the optimal focal position, for estimating the flux density onthe target and for measuring the electron temperature of the plasma. In combination with a focusing von Hamosspectrometer (curved mica and graphite crystals, radius of curvature R = 20 mm) the detector was used for absolutespectral measurements and determination of the plasma parameters. This spectrometer is promising for absolute spectralmeasurements of x-ray radiation of low-intensity sources and for numerous practical applications (e.g., x-ray fluorescence