A simple XUV transmission grating spectrograph with sub-ångström resolution for laser-plasma interaction studies

Abstract

A simple XUV transmission grating spectrograph operating in the wavelength range 3-90 Å with sub-ångström resolution without using any XUV imaging optics is described. This is based on a free-standing gold microstructure grating of 2000 Å period in normal incidence geometry. A spectral resolution of 0.6 Å is obtained by optimizing the slit aperture, the source-to-grating distance and the grating-to-detector distance. Electron temperatures deduced from analysis of the spectrum of a laser-produced magnesium plasma using a plasma spectroscopic code are consistent with theoretical considerations. The spectral range can be extended to higher wavelengths by using a larger detector. The simple geometry and ease of operation of the spectrograph should make it useful in many experiments such as those involving plasma-based XUV lasers and odd-harmonic generation in the XUV spectral region using ultra-short laser pulses.

Transmission grating spectrograph with on-line recording of XUV soft X-ray spectra from laser produced plasmas

“…Our results with magnesium spectra may be compared to other published results [1,11]. Arora et al [1] have recorded X-ray spectra of magnesium plasma in the 6.9-8.2 Å region, using a crystal spectrograph.…”

“…This was determined by both diffraction and geometric resolution and has been described in detail elsewhere [11]. The limit of spectral resolution introduced by these detectors is determined from the product of their spatial resolution and the plate factor of the spectrograph.…”

“…The latter were kept at 1150 mm and 570 mm, respectively, giving a plate factor of $3.5 Å /mm. This set-up is similar to our earlier spectrograph [11], in which X-ray film was used as detector. In our present work, the X-ray film has been replaced by an on-line detector system, consisting of a microchannel plate (MCP) in conjunction with an image intensifier (II) tube and CCD camera.…”

“…Transmission grating spectrographs (TGS) have been widely used [4][5][6][7][8][9][10][11][12][13] spectral resolution of 1.5-3 Å . A sub-angstrom resolution is useful in many such studies and may be achieved in a simple normal incidence geometry without the use of any optics, by using a high dispersion grating as a diffraction element and optimizing the geometrical parameters of the spectrograph [10,11]. X-ray films are very often used as detectors, but due to their characteristic low sensitivity combined with the small collection solid angle of the instrument, multiple shots are required for recording the X-ray emission spectra.…”

A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility

“…The simple expression for spectral resolution is given by combining the geometric resolution limited by blurring due to the finite source size and ideal diffractive resolution in quadrature (Sailaja 1998…”