Results from the NSTX X-ray Crystal Spectrometer
A high-resolution X-ray crystal spectrometer has recently been installed at the National Spherical Torus Experiment to record the satellite spectra of helium-like argon, ArXVII, in the wavelength range from 3.94 to 4.00 {angstrom} for measurements of ion and electron temperatures, and measurements of the ionization equilibrium of argon, which is of interest for studies of ion transport. The instrument presently consists of a spherically bent quartz crystal and a conventional one-dimensional position-sensitive multi-wire proportional counter, but it will soon be upgraded to a new type of X-ray imaging crystal spectrometer by the installation of a large size (10 cm x 30 cm) two-dimensional position-sensitive detector that will allow us to obtain temporally and spatially resolved spectra from an 80 cm high cross-section of the plasma. In its present configuration, the spectrometer has been optimized for high throughput so that it is possible to record spectra with small statistical errors with a time resolution of 10 ms by adding only small, nonperturbing amounts of argon to the plasma. The spectrometer is most valuable for measurements of the ion temperature in the absence of a neutral beam in ohmically heated and radio-frequency heated discharges, when charge exchange recombination spectroscopy does not function. Electron temperature measurements from the satellite-to-resonance line ratios have been important for a quantitative comparison with (and verification of) the Thomson scattering data. The paper will describe the instrumental details of the present and future spectrometer configurations, and present recent experimental results.
- Research Organization:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Organization:
- USDOE Office of Science (US)
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 809961
- Report Number(s):
- PPPL-3766; TRN: US0302659
- Resource Relation:
- Other Information: PBD: 14 Jan 2003
- Country of Publication:
- United States
- Language:
- English
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