No abstract

The x-ray imaging crystal spectrometer (XICS) for the Korea Superconducting Tokamak Advanced Research has been first applied for the experimental campaign in 2009. The XICS was designed to provide measurements of the profiles of the ion and electron temperatures from the heliumlike argon (Ar XVII) spectra. The basic functions of the XICS are properly working although some satellites lines are not well matched with the expected theoretical values. The initial experimental results from the XICS are briefly described.

A new type of high-resolution x-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument is particularly valuable for diagnosing plasmas with purely ohmic heating and rf heating, since it does not require the injection of a neutral beam-although it can also be used for the diagnosis of neutral-beam heated plasmas. The spectrometer consists of a spherically bent quartz crystal and a two-dimensional position-sensitive detector. It records spectra of helium-like argon (or krypton) from multiple sightlines through the plasma and projects a de-magnified image of a large plasma cross section onto the detector. The spatial resolution in the plasma is solely determined by the height of the crystal, its radius of curvature, and the Bragg angle. This new x-ray imaging crystal spectrometer may also be of interest for the diagnosis of ion temperature profiles in future large tokamaks, the Korea Superconducting Tokamak Advanced Research tokamak and the International Thermonuclear Experimental Reactor, where the application of the presently used charge-exchange spectroscopy will be difficult, if the neutral beams do not penetrate to the plasma center. The article presents the results from proof-of-principle experiments performed with a prototype instrument at Alcator C-Mod.

The engineering design for two high-resolution x-ray imaging crystal spectrometers for KSTAR tokamak has been completed. A spherically bent quartz crystal and a large area two-dimensional (2D) position-sensitive multiwire proportional counter have been selected for the imaging spectrometers. A prototype 10 cm by 30 cm 2D detector was fabricated and pilot measurement on Alcator C-Mod tokamak was carried out. The final engineering design of the spectrometers and experimental results from the 2D detector are presented.

No abstract