DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 297: Effect of Error Fields and RMPs on H-mode power threshold and transport barrier | ||
| Name: | Richard A. Moyer ( |
Affiliation: | University of California, San Diego |
| Research Area: | Transport | Presentation time: | Requested | Co-Author(s): | Evans |
| Description: | Goals: 1. Use the I-coil to create controlled "error field" mode spectra and strengths 2. Measure the H-mode power threshold versus RMP mode spectrum and amplitude 3. Quantify changes to the edge Er, plasma flows, fluctuations, and transport 4. If available, use dedicated midplane probe heads for 1) electrostatic Reynolds stress and 2) Maxwell stress (i.e. magnetic component of the turbulent Reynolds stress) to quantify the effect of the RMPs on the turbulent Reynolds stresses (requires separate run days for the two stresses) | ||
| Experimental Approach/Plan: | Experimental approach: 1. Use ECH L-mode and H-mode discharges to facilitate probe measurements in the H-mode pedestal as in last year's experiment 2. Apply I-coil perturbations with varying current 3. Increase ECH power to determine change/increase in H-mode power threshold while plunging reciprocating probes 4. Switch to modulated beams to repeat determination of power threshold while acquiring edge CER and BES measurements. | ||
| Background: | Motivation: 1. Plasma flows, radial electric field, turbulence, and transport are all closely coupled in the plasma boundary. 2. Error fields and externally applied RMPs can significantly alter the edge Er shear and plasma flows, and consequently the plasma turbulence and transport 3. Last year, externally applied RMPs were observed to raise the H-mode power threshold from 1/4 neutral beam source (about 0.6 MW) to more than 4 sources, confirming that RMPs can significantly alter the physics of the L-H transition and transport barrier formation. | ||
| Resource Requirements: | complete control of the initial portion of the discharge (power, shape, diagnostics) to optimize probe data from inside the separatrix
1 run day 4 gyrotrons for ECH H-modes electrostatic Reynolds stress head on midplane probe | ||
| Diagnostic Requirements: | midplane and Xpoint probes; midplane with Reynolds stress head
BES and CER with discharge shape to allow measurements on the same flux surfaces as the midplane probe. Fluctuation diagnostics consistent with ECH heating pedestal diagnostics | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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