High resolution absorption spectroscopy of exploding wire plasmas using an x-pinch x-ray source and spherically bent crystal

Abstract

We present here the use of absorption spectroscopy of the continuum radiation from x-pinch-produced point x-ray sources as a diagnostic to investigate the properties of aluminum plasmas created by pulsed power machines. This technique is being developed to determine the charge state, temperature, and density as a function of time and space under conditions that are inaccessible to x-ray emission spectroscopic diagnostics. The apparatus and its characterization are described, and the spectrometer dispersion, magnification, and resolution are calculated and compared with experimental results. Spectral resolution of about 5000 and spatial resolution of about 20 μm are demonstrated. This spectral resolution is the highest available to date in an absorption experiment. The beneficial properties of the x-pinch x-ray source as the backlighter for this diagnostic are the small source size (<5 μm), smooth continuum radiation, and short pulse duration (<0.1 ns). Results from a closely spaced (1 mm) exploding wire pair are shown and the general features are discussed.

Hard X-rays from hybrid X pinches

“…It is well known that X-pinches in different configurations are in use now as point sources of soft x-ray for different applications [1,2], but mostly as a source for point-projection imaging of plasma objects [3]. Higher energy X-ray radiation in the 8-100 keV range is also emitted [4,5].…”

Compact Z-pinch radiation source dedicated to broadband absorption measurements

“…To diagnosis such medium, the absorption method is often used with a backlighter created for instance by focusing a laser beam on a thin metal foil [18] or by using an X-pinch [19]. Our source is designed for wavelengths of 200-400 nm which are far away from those necessary for HEDP diagnosis.…”

A doubly curved elliptical crystal spectrometer for the study of localized x-ray absorption in hot plasmas

“…[1][2][3] This is in contrast to x-ray emission spectroscopy which generally requires higher temperatures before signals sufficiently above the system noise floor can be recorded. The primary cause of this requirement is that emission spectra are visible only when adequate populations of excited ions are present.…”