Bragg rotor spectrometer for tokamak diagnostics

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Abstract
A high-throughput broadband (1–24-Å) x-ray spectrometer has been demonstrated on the divertor injection tokamak experiment (DITE) tokamak. A hexagonal rotor supporting six diffractors may be driven in several modes, ranging from a full spectral survey at ∼10 Hz to a stationary, monochromator mode. Wavelength resolution, 500≲λ/Δλ≲1000, is governed by gridded or slotted collimators. A multiwire gas proportional counter provides a measure of energy discrimination, which together with the large instrument aperture, gives sufficient sensitivity and signal/noise ratio to allow measurement of the continuum radiation from the tokamak. The instrument has a self-contained vacuum system which allows full spatial scans of the DITE plasma. Data acquisition and drive mechanisms for the rotor and filter selection, are controlled remotely from a computer. Results are presented of fast spectral surveys and time evolution of impurity emission during impurity injection.