DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 106: Isolating particle sources and sinks in RMP H-modes with core pellet fueling | ||
| Name: | Todd E. Evans ( |
Affiliation: | General Atomics |
| Research Area: | ELM Control & Pedestal Physics | Presentation time: | Not requested | Co-Author(s): | tbd |
| Description: | The goal of this experiment is to establish a quantitative connection between core fueling with deuterium pellets, particle confinement, wall recycling and particle exhaust via the cryopumps. | ||
| Experimental Approach/Plan: | In this experiment we will attempt to separate the effects of pumping and recycling from changes in core transport by reproducing discharges with the same pellet and I-coil parameters while moving the OSP away from the cryopump entrance during the stationary ELM suppressed phase of the discharge. This will be done with several I-coil currents and q95 values to establish a clear dependence between the particle loss rate and changes in the recycling/pumping. during a separate scan we will increase the upper gap and reduce the upper triangularity to reduce the coupling to the upper cryopump and to recycling surfaces in the upper divertor. If time permits we would also like to vary the pellet velocity and deposition profile as well as use the LFS pellet injector to determine how these affect the particle loss rate and wall recycling/pumping. Finally a 3 point NBI power scan will be done using one of the configurations from earlier in the run day. Theree will also be time at the end of these disgharges for RMP related piggybacks. | ||
| Background: | Preliminary experiments last year with HFS pellets demonstrated that the decay rate of the core density due to an individual fueling pellet is controlled by the amplitude of the applied n=3 I-coil RMP. It was found that the pressure in both the upper and lower cryopumps was altered by changing the amplitude of the RMP during HFS pellets In additon, the D_alpha recycling following each pellet and the evolution of the pedestal pressure profile were controlled by increasing the level of the I-coil current. A key issue for understanding issue for understanding RMP ELM and pedestal control is what causes the density pump out effect. | ||
| Resource Requirements: | 7 kA I-coil, 5 co-NBI sources, upper and lower cryopumps with HFS and LFS pellet injectors. | ||
| Diagnostic Requirements: | Full RMP H-mode diagnostic set including upper and lower ASDEX gauges, upper and lower divertor Langmuir probes, upper and lower filterscopes, pellet diagnostics, tangential TVs, IR cameras, UCSD fast camera, UCLA profile reflectometer. | ||
| Analysis Requirements: | TRIP3D, SOLPS5/EIRENE and EMC3/EIRENE, python pedestal tools and kinetic EFITs. | ||
| Other Requirements: | -- | ||
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