DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 181: Vertical Stability Control Physics for ITER | ||
| Name: | Dave Humphreys ( |
Affiliation: | General Atomics |
| Research Area: | ITER Startup, Shutdown, Vertical Stability | Presentation time: | Requested | Co-Author(s): | T. Casper, M. Cavinato, J. Lister, A. Portone, M. Walker, A. Welander |
| Description: | The goals of this 2-day experiment are to study the fundamental limits of vertical controllability of DIII-D with two different control coil sets and in such a way as to experimentally quantify controllability metrics being used for ITER design. The key performance quantities to be determined are the maximum stabilizable growth rate and the maximum displacement that can be restored following an uncontrolled VDE drift. Certain key disturbances will also be triggered and characterized, and the control responses to these disturbances will be quantified. This falls under a new ITPA joint experiment topic being considered by the ITPA MHD, Disruptions, and Control Group. | ||
| Experimental Approach/Plan: | Using ITER similarity plasmas, increase elongation in steps, holding for periods > 10-20 growth times. Determine highest growth rate sustainable with no VDE onset, and growth rate beyond which VDE is guaranteed (or extremely likely). Using targets near maximum growth rate, freeze coil commands to disable vertical/shape control for varying lengths of time, allowing VDE. Apply explicit step command to control coils to determine maximum displacement beyond which instability cannot be suppressed. Perform with both ITER-like coilset (PF6,7 only) and with usual (including PF2) coilset. Perform in ohmic and H-mode plasmas. Produce disturbances near control limits by dropping beams, either staying in H-mode or dropping to L-mode. Possibly inject impurity gas to contract current channel to cause delta-li perturbation. | ||
| Background: | |||
| Resource Requirements: | 3-4 beams (co), PCS modification | ||
| Diagnostic Requirements: | MSE, 5 kHz magnetics sampling | ||
| Analysis Requirements: | standard EFITs, TokSys, Corsica | ||
| Other Requirements: | -- | ||
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