Development of a Single-Crystal X-ray Spectropolarimeter and Application to Wire-Array Z-pinches
AuthorWallace, Matthew Steven
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Energetic direction electrons are common in z-pinch plasmas. Such energetic electron beams have been measured directly after exiting the pinch region, but are usually inferred from the observation of hard x-ray bursts. Spectroscopy is the way to diagnose plasmas, and because anisotropies such as electron beams can lead to the partial polarization of the emitted radiation, polarization spectroscopy, or spectropolarimetry, can be used to diagnose these environments. Spectropolarimetry in the x-ray spectral range extends the applicability of this technique to highly anisotropic high energy density plasmas. X-ray spectropolarimetry is typically performed with two crystals and works well for single compact point-like sources. However, z-pinch plasmas rarely contain one point-like x-ray emitting region, limiting the amount of useful shots for spectropolarimetric information.An x-ray spectropolarimeter with a recently developed polarization-splitting single crystal produces two orthogonal sets of linearly polarized x-ray spectra and can replace usual two-crystal schemes for measuring x-ray polarization. This instrument has been built and tested on wire array z-pinches. Since each x-ray emitting region potentially has a different polarization, the spectropolarimeter must be spatially resolved to obtain meaningful spectra. With the use of a collimating series of slits, the single-crystal x-ray spectropolarimeter may be used to provide spatial resolution in such a system. Development of a single-crystal x-ray spectropolarimeter and spatially resolved results obtained with the use of a collimating are the topic of this dissertation.