High resolution measurements of ion temperatures in z-pinch plasmas

Abstract

The Doppler broadening of ion line profiles emitted by z-pinch plasma provides information about the thermalization of the implosion kinetic energy and the radiation efficiency of the pinch. Measurements of these line profiles are often complicated by source broadening in the instrument and opacity broadening of the emitted radiation. A high resolution concave crystal spectrometer in the Johann geometry was used to record the time averaged spectra of optically thin trace elements in the load. An imaging slit provided radially resolved but axially averaged spectra. The measurements indicate that lower ion temperatures ͑3-5 keV͒ are observed for Al wire loads on both the Saturn and Double EAGLE accelerators in the short current pulse mode ͑60-100 ns͒ than in the long pulse mode ͑125-225 ns͒ where values of 6.3-9.5 keV are observed. These values are smaller than those observed on Saturn by others. Furthermore, the wavelength at the line center of axially resolved ion line profiles on the DM-2 accelerator at Titan was observed to vary about some average value which implies an axially varying fluid motion of the plasma column transverse to the pinch axis.

Spatially-resolved spectroscopic diagnosing of aluminum wire array Z-pinch plasmas on QiangGuang-I facility

“…5) that is free of opacity broadening and Stark broadening. [15] Figure 6 shows its line shape of shot No. 07329.…”

“…[12,14] The ion temperature was mainly determined by Doppler broadening of line emissions. [13,15] It is noticeable that the broadening caused by other factors such as source size, opacity effect and Stark broadening should be carefully extracted, or one may choose a specific line, of which the width is dominated by Doppler broadening. [15] Ideally, these would be done with spatial and temporal resolutions simultaneously, but it is difficult to realise in practice.…”

“…[13,15] It is noticeable that the broadening caused by other factors such as source size, opacity effect and Stark broadening should be carefully extracted, or one may choose a specific line, of which the width is dominated by Doppler broadening. [15] Ideally, these would be done with spatial and temporal resolutions simultaneously, but it is difficult to realise in practice. We develop two spatially-resolved crystal spectrometers and apply them to Z-pinch experiments.…”

Stability of a nonlinear magnetic field diffusion wave

“…27,41 The electrical explosion at these current densities has become the subject of much research in the last 15 yr, because they are attained in wire arrays accelerated with the use of megaampere generators. [42][43][44][45] At the final stage of implosion of a wire array, dense high-temperature plasma is generated. It is planned to use the radiation of this type of plasma in attempting to achieve controlled inertial thermonuclear fusion.…”