Instrumentation Division Seminar

Recently developed one-dimensionally imaging high resolution x-ray spectrometers using a single spherically bent crystal and Pilatus PAD arrays, or 2D multiwire proportional counters, have revolutionized Doppler spectroscopic measurements of plasma ion temperature and flow velocity in tokamak plasmas worldwide by providing, from a single instrument, measurements over the entire extended plasma cross section. We have collaborated with groups to install and operate such spectrometers on tokamaks and stellarators at MIT and in Japan, China, and Korea, and are presently developing the conceptual design for a set of such x-ray imaging crystal spectrometers (XICS) for the international tokamak, ITER, which is being constructed in Cadarache, France. This XICS instrument is also applicable for Doppler measurements of inertial confinement fusion (ICF) plasmas, such as the National Ignition Facility (NIF). Additional schemes have been developed which eliminate the astigmatism by use of specially matched pairs of spherically bent crystals and which provide 2D x-ray imaging with almost arbitrary angles of incidence over millimeter scales with potential spatial resolution of microns. These x-ray optical schemes may also have beneficial applications in other areas, such as x-ray lithography, x-ray microscopy for biological research on x-ray light sources, or x-ray beam steering, focusing, and monochromatization at synchrotron facilities. An overview of the 1D imaging Doppler spectroscopy on present tokamaks, performance simulations for the ITER spectrometers, and preliminary testing of the 2D imaging schemes in visible light will be presented, as well as planning and progress on testing the 2D imaging schemes with x rays.