A Multi Megahertz Position Sensitive GEM Detector for Plasma Diagnostics

70264 New, non-perturbing techniques for measuring crucial plasma parameters (such as ion temperature, electron temperature and ionization equilibrium) are needed for present and future generations of large fusion devices. This project will develop an instrument called the X-ray Crystal Imaging Spectrometer that can directly measure these parameters by spectrally resolving x-ray emission lines. A large area, two-dimensional imaging x-ray detector can spatially resolve these measurements along a chord of the plasma and collect hundreds of spectra across the plasma on timescales of order 10 ms. Specific performance goals of the design include (1) spatial resolution less than or equal to 200 ¿m FWHM, (2) potential formats greater than 10 cm, (3) total detector rates greater than 2 million events per second, with local rates greater than 104 events per mm2 per second, (4) average quantum efficiency greater than or equal to 60% over the range 3-13 keV, (5) long lifetime operation (greater than 1 Coulomb/cm2) with minimal change in operating characteristics, and (6) operational stability and reliability over a wide range of environmental conditions. Phase I will build a test-bed GEM detector with an existing cross delay line (XDL) anode (65mm) and perform a number of feasibility tests to demonstrate that the GEM and a delay line readout will work as a detector scheme. Phase I will also design an Interpolating Time Converter (ITC), the delay line readout electronics that has a time jitter of ~4 ps and a deadtime of 40 ns per event. Commercial Applications and Other Benefits as described by the awardee: The X-ray Crystal Imaging Spectrometer should have use on all current and future fusion devices. Outside the fusion field, medical imaging devices and biological research imaging of P33 tagged microarrays could take advantage of the area and speed to increase research throughput. The ITC electronics could provide inherently far superior performance than currently available for Time-of-Flight mass spectroscopy research and fluorescent decay investigations. Another possible application is time spectroscopy related to dynamic emission diagnostic techniques for semiconductor microchip designs.