7 research outputs found
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ITER ECE: Plans and Challenges
Measuring ECE in ITER plasmas will present several difficulties in both hardware and physics that will impede efforts to determine Te(r,t) and characteristics of the electron distribution function. Recent work on the diagnostic systems and techniques to be employed on ITER has clarified some of these issues and found some solutions. Studies show that even with the greater relativistic broadening due to the high electron temperature, Te measurements with spatial resolution of 6-10 cm are still possible especially with properly designed front end optics and instruments. ECE will still be able to provide high resolution Te profiles in both core and edge regions and even follow oscillations of high m,n TAE modes. Of greater concern is the possibility and effects of non-Maxwellian electron distributions created by intense auxiliary heating. In these cases modeling will have to be used to correct and define the valid limits of Te from ECEand a special oblique viewing antenna is recommended. The planned ECE instruments, heterodyne radiometer and Michelson interferometer, will provide complementary measurement capabilities. A viable in-port-plug calibration source for these instruments is a concern; progress on work being done to develop a prototype is reported.Center for Electromechanic
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Status of the design of the ITER ECE Diagnostic
The baseline design for the ITER electron cyclotron emission (ECE) diagnostic has entered the detailed preliminary design phase. Two plasma views are planned, a radial view and an oblique view that is sensitive to distortions in the electron momentum distribution near the average thermal momentum. Both views provide high spatial resolution electron temperature profiles when the momentum distribution remains Maxwellian. The ECE diagnostic system consists of the front-end optics, including two 1000 K calibration sources, in equatorial port plug EP9, the 70-1000 GHz transmission system from the front-end to the diagnostics hall, and the ECE instrumentation in the diagnostics hall. The baseline ECE instrumentation will include two Michelson interferometers that can simultaneously measure ordinary and extraordinary mode ECE from 70 to 1000 GHz, and two heterodyne radiometer systems, covering 122-230 GHz and 244-355 GHz. Significant design challenges include 1) developing highly-reliable 1000 K calibration sources and the associated shutters/mirrors, 2) providing compliant couplings between the front-end optics and the polarization splitter box that accommodate displacements of the vacuum vessel during plasma operations and bake out, 3) protecting components from damage due to stray ECH radiation and other intense millimeter wave emission and 4) providing the low-loss broadband transmission system.Center for Electromechanic
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The possible occurrence of multi-phase behavior in the high T sub c superconductor YBa sub 2 Cu sub 3 O sub x
We report here the results obtained for powder diffraction studies on four YBa{sub 2}Cu{sub 3}O{sub x} samples in which a model with two orthorhombic phases was used to obtain an improved agreement. The implications of this structural model on the systematic variation of {Tc} with oxygen content will be discussed. 28 refs., 3 figs., 2 tabs
Interaction in vitro between synovial cells and autologous lymphocytes and sera from arthritis patients.
Synovial cells from patients with rheumatoid arthritis (RA) when grown in vitro in media supplemented with 20% fetal calf serum failed to show any difference in growth rate, life span, uptake of tritiated thymidine or cellular and nuclear characteristics when compared with synovial cells from patients with osteoarthritis or other joint diseases grown similarly in 20% serum enriched medium. There was also no evidence that lymphocytes and/or sera from RA patients were more cytotoxic to autologous synovial cells than sera and/or lymphocytes from OA patients. It is unlikely that antisynovial antibodies or lymphocytes from RA patients act as triggers for synovial damage