X-pinch plasma conditions from time resolved x-ray spectroscopy

X-pinch plasmas, produced by exploding two or more 10–50 μm metal wires that cross and touch in the middle in the form of an X, have been successfully developed as point sources of soft x rays for radiography. However, the parameters of the x-ray source as a function of time, space and wavelength band are not well understood. To determine the X-pinch plasma characteristics, time-resolved x-ray spectra produced by two- and multiwire X pinches made from different wire materials were recorded using an x-ray streak camera. A spherically bent mica crystal spectrograph was used with a ∼10 ps time resolution x-ray streak camera in a slitless configuration. Some spectra were dominated by continuum and others by line radiation, and observed spectral features varied on time scales ranging from 10 to 1000 ps, depending on the wire material. Electron temperatures and densities in Ti X pinches were estimated from line ratios based upon collisional-radiative calculations, and from the time delay between the appearance of He-like and H-like Ti lines, respectively, indicating peak values of ∼2.5 keV and ∼2×1023/cm3. Results are presented that demonstrate the necessity for 10–100 ps time-resolution spectral data to obtain plasma conditions from micropinch x rays.