High-efficiency hard x-ray spectrometer for sub-ps laser-produced plasma investigations

Abstract

ABSTRACT Johann and DuMond quartz ciystal focusing spectrometers are proposed for hard x-ray spectra investigations of sub-ps laser-produced plasmas when the source is located on the focal circle. Because the ciystal intercepts and focuses a large solid angle of radiation, the schemes have extremely high efficiency, which could be iO times higher than those of flat crystal spectrometers. Due to the small size ofthe source (usually 4O xm) the schemes have a high spectral resolution (?/dA>2OOO).By using reflection (Johann spectrometer) and transmission (DuMond spectrometer) modes, the schemes cover a very widespectral range: 0.2-2.3 A (energy range E=5-60 key). Curved quartz crystal (jlane 1340, 2d=2.34 A, radius ofcurvature 150mm) is tested in the reflection mode using Fe K, radiation ()=1.94 A).Keywords: x-ray spectroscopy, plasma diagnostics, laser-produced plasmas, advanced x-ray instrumentation. 1. INTRODUCTION The interaction ofa sub-ps laser with a high-Z target produces a hard x-ray continuum, which has several potential applicationsfor spectroscopy, biology and medicine. The other feature of this interaction is a possibility to excite the characteristic lineemission of high-Z elements from a sub-ps laser-produced plasma. The electron oscillation energy €(keV) in a light field E0,intensity q (W/cm2) with a wavelength tm) is given by