Thesis

A high-energy resolution x-ray spectrometer with interchangeable detectors (HEX-ID) for short-pulse laser-plasma experiments

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Awarding institution
  • University of Strathclyde
Date of award
  • 2012
Thesis identifier
  • T13219
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Abstract
  • High resolution, soft x-ray spectroscopy is a useful and flexible diagnostic technique which has been applied to plasma physics experiments for many years. Examples of previous instruments that have utilised the technique include the Henway [1] spectrometer developed at LLNL, and later the HENEX [2] spectrometer, which has been fielded on experiments at both OMEGA and NIF. The design of these previous x-ray spectrometers has been analysed in order to produce a four channel high-energy x-ray spectrometer (HEX-ID) with superior resolution. The shielding has been adapted for use on short-pulse laser-plasma experiments. HEX-ID is intended for: analysis of characteristic x-ray line spectra from backlighter materials (laser irradiated materials producing x-rays to interact with a secondary target); identification of plasma ion species and their charged states; measurement of plasma opacity and of the absolute conversion efficiency of characteristic x-ray line emissions. The spectrometer will be fielded at the new Orion laser facility at AWE (UK) and at OMEGA (USA). The minimum theoretical resolving power, E/δE, of HEX-ID (~730) has been improved upon that of HENEX (~500). The enhancement in resolving power has been achieved by reducing the crystal radius-of-curvature and allowing a variation in the crystal-to-detector distance, which can be manually set before TIM-based deployment. Four convex reflection crystals provide a total spectral range of approximately 1.2 to 9.8 keV in overlapping bands. The crystals were characterised using the Excalibur soft x-ray facility at AWE to determine their reflectivity values for a range of x-ray energies. In order to achieve a desired spectral and temporal resolution, adapt the spectrometer dynamic range to long-pulse and short-pulse laser shots, as well as for cross-channel comparison of the energy dispersion and spectral range, HEX-ID can utilize a number of detectors. These are image plate, CMOS and PCD. The spatial resolution of different IP systems was investigated, which indicated the FUJI BAS TR IP scanned with the Fuji FLA7000 scanner is best. Spatial resolution tests were also carried out with the CMOS sensors to compare to the IP.
Resource Type
DOI
Date Created
  • 2012
Former identifier
  • 947839

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