Multilayer mirror and foil filter AXUV diode arrays on CDX-U spherical torus
Recent upgrades to CDX-U spherical torus diagnostics include two 10-channel AXUV diode arrays. The multilayer mirror (MLM) array measures the {lambda}150 O VI brightness profile in the poloidal plane using the Mo/B{sub 4}C synthetic multilayer structures as dispersive elements. The foil filter array has a tangential view and is equipped with interchangeable clear aperture, beryllium and titanium filters. This allows measurements of radiated power, O VI or C V radial distributions, respectively. The O VI and C V emissivity and the radiated power profiles are highly peaked. A Neoclassical impurity accumulation mechanism is considered as an explanation. For radiated power measurements in the T{sub e}{<=}100 eV plasmas, photon energy dependent corrections must be used in order to account for nonlinear AXUV sensitivity in the range E{sub phot}{<=}20 eV. The arrays are also used for characterization of resistive MHD phenomena, such as the low m modes, saw-tooth oscillations and internal reconnection events. Based on the successful operation of the diagnostics, a new ultra soft x-ray multilayer mirror diode AXUV diode array monitoring the 34 Aa emissivity distribution of C VI will be built and installed on the National Spherical Torus Experiment.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40204844
- Journal Information:
- Review of Scientific Instruments, Vol. 72, Issue 1; Other Information: Othernumber: RSINAK000072000001000737000001; 685101CON; PBD: Jan 2001; ISSN 0034-6748
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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