Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited)
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
- Lawrence Livermore National Laboratory, California 94550 (United States)
- DECTRIS Ltd., Villigen-PSI 5232 (Switzerland)
- National Fusion Research Institute, Yusung, Taejeon 305-333 (Korea, Republic of)
The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage of a new x-ray imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in x-ray detector technology [Ch. Broennimann et al., J. Synchrotron Radiat. 13, 120 (2006)], a spatially resolving high resolution x-ray spectrometer has been built and installed on the Alcator C-Mod tokamak. This instrument utilizes a spherically bent quartz crystal and a set of two dimensional x-ray detectors arranged in the Johann configuration [H. H. Johann, Z. Phys. 69, 185 (1931)] to image the entire plasma cross section with a spatial resolution of about 1 cm. The spectrometer was designed to measure line emission from H-like and He-like argon in the wavelength range 3.7 and 4.0 A with a resolving power of approximately 10 000 at frame rates up to 200 Hz. Using spectral tomographic techniques [I. Condrea, Phys. Plasmas 11, 2427 (2004)] the line integrated spectra can be inverted to infer profiles of impurity emissivity, velocity, and temperature. From these quantities it is then possible to calculate impurity density and electron temperature profiles. An overview of the instrument, analysis techniques, and example profiles are presented.
- OSTI ID:
- 21266467
- Journal Information:
- Review of Scientific Instruments, Vol. 79, Issue 10; Other Information: DOI: 10.1063/1.2968707; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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