Abstract Details
X-RAY POLARIZATION SPECTROSCOPY FROM DENSE PLASMAS FOR FAST ELECTRON VELOCITY DISTRIBUTION MEASUREMENTS
Author: Nicola Booth
Requested Type: Oral Only
Submitted: 2009-04-21 15:38:43
Co-authors: R. Clarke, L. A. Gizzi, G. Gregori, P. Koester, L. Labate, T. Levato, B.Li, M. Makita, J. Pasley, P.P Rajeev, D. Riley, E. Wagenaars, J. N. Waugh, N. C. Woolsey
Contact Info:
Department of Physics, University of York
Goodricke Way
Heslington, York, North York 0000000
UK
Abstract Text:
Detailed knowledge of the fast electron energy transport is crucial to the understanding of energy transport in high energy density matter beyond the critical density. This is a problem relevant to many areas of laser-plasma physics with particular importance to fast ignition, necessary for large-scale facilities such as HiPER. We report on recent experiments undertaken on the Vulcan Petawatt laser at the Central Laser Facility, UK to record polarisation measurements from buried layer nickel and sulphur targets at high intensities of 1019 – 1021 Wcm-2. Observations were made of the Ly-α doublet using two sets of orthogonal highly-oriented pyrolytic graphite (HOPG) crystal spectrometers operating at 45o in the 3rd order of Ni and 1st order of sulphur. By operating HOPG crystals at 45o the crystal acts as an ideal polariser and monitors the x-ray σ- and π-polarisation ratio in the orthogonal directions. X-ray polarisation spectroscopy is a useful diagnostic tool for the measurement of the electron velocity distribution. Spectroscopic measurements of the K-α and K-shell emission lines provides details of the energy deposition processes and provides more information as the fast-electron beam preferentially populates certain excited state magnetic sub-levels which results in polarised x-ray emission from these excited states.
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