DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 489: Relativistic effects on profile reflectometry and a new potential Te measurement | ||
| Name: | Lei Zeng ( |
Affiliation: | University of California, Los Angeles |
| Research Area: | General IP | Presentation time: | Not requested | Co-Author(s): | W.A. Peebles, E.J. Doyle, T.L. Rhodes, G. Wang |
| Description: | The goal of this experiment is, first to investigation the relativistic effects on the reconstruction of ne profile via reflectometry in high Te. Second, by using this effect and dual polarization (O- and X- mode) measurement of profile reflectometry, test a new potential Te profile measurements. | ||
| Experimental Approach/Plan: | Create discharge with BT ~ 1.5 T, major radius of magnetic axis ~ 1.83 m, and LCFS in mid-plane ~ 2.29 m, in order to make fce layer as flat as possible in low field and fce at the edge ~ 34 GHz. The ne profile is with ne0 ~ 2.9 x10^19 m^-3, and ~1.3 x10^19 m^-3 at the top of edge pedestal. By using ECH, increase Te (10 keV or higher) in the center. Using profile reflectometer (dual mode operation as usual), measure O- and X- mode phases simultaneously. Reconstruct ne and Te profiles via reflectometry. And the results compare to ece and TS measurement. | ||
| Background: | Profile reflectometry will be important diagnostic in ITER. However, with high Te in ITER, the cold-plasma electromagnetic theory doesn�??t work. Plasma cutoff frequencies will be downshift due to the relativistic effect, which bring a measurement challenge to reflectometry. In DIII-D with high power ECH, Te can be increased to above 10 keV, the relativistic effect can be evaluated. Furthermore, for the dual mode measurements of reflectometry (as currently running in DIII-D), both O- and X-mode measured phases are modified by the relativistic effect independently. Through the analysis for these two sets of phase, both ne and Te profile can be reconstructed. The novel measurement technique has been published in PPCF (vol. 49, p. 1277)this year. It is really good to test this new technique in DIII-D, since the reconstructed results can cross check with ECE and TS measurements. | ||
| Resource Requirements: | ECH | ||
| Diagnostic Requirements: | profile reflectometry, ECE, TS | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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