DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 381: Rapid-pulse Thomson Scattering scans in initial phase of RMP discharges | ||
| Name: | Zeke Unterberg ( |
Affiliation: | ORISE/ORNL |
| Research Area: | Boundary | Presentation time: | Not requested | Co-Author(s): | B. Bray |
| Description: | The goal of this measurement would be to obtain high temporal resolution edge T_e and n_e profiles when the I-coils are first initiated. The fast time evolution of the T_e profile as the I_coils turn on would be of main interest. Langmuir probe data from past RMP discharges have shown a burst of fast electrons during the initial I-coil activation and there is thought to be an initial transient T_e decrease before n_e decreases and the edge temperature gradients then increase. These measurements would be an attempt to quantify this phenomenon. | ||
| Experimental Approach/Plan: | These measurements could piggyback on any RMP run day. The idea would be to multi-pulse the TS laser during the first few milliseconds of turning on the I-coils. This would most likely be done on the "Core" chord of the TS system. Although, the measurement could also be done on the divertor chord. The minimum time between pulses is 100 microsec (usec) and is limited by the data acquisition time. Therefore, this proposal would be to scan rapid pulse times from ~ 100 usec to ~ 1 msec in order to measure during the entire window of the fast tranisent in T_e. Ideally, this would be repeated for multiple shots for averaging with a range of times around the I_coil turn on. | ||
| Background: | -- | ||
| Resource Requirements: | Core chord TS setup to allow cascade firing of 7 lasers. This measurement chould piggyback on any run day with up to 4 lasers on the Core chord, but it would be most desirable to arrange the lasers to have all 7 on the core chord. This wourd take ~ 1 day to set up. | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | TS profile fitting routines | ||
| Other Requirements: | -- | ||
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