DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 36: FW-only H-mode studies | ||
| Name: | Robert I. Pinsker ( |
Affiliation: | General Atomics |
| Research Area: | Heating & Current Drive | Presentation time: | Not requested | Co-Author(s): | F.W. Baity, J.C. Hosea, M. Porkolab, E. Fredd |
| Description: | The fact that H-mode transitions were observed with fast wave power as the only auxiliary heating source, under conditions of rather low single-pass absorption was an important piece of evidence that multiple-pass absorption can be efficient. By expanding the range of rf frequencies, densities (and hence target electron temperatures), and using 3rd harmonic ECH, we can get a more quantitive measurement of the edge losses by determining the L-H transition threshold power under varying single-pass absorption conditions. | ||
| Experimental Approach/Plan: | The experiment consists of scans of target density, rf power (at two different frequencies: 60 MHz and ~90 MHz), toroidal field, and whether 3rd harmonic ECH is added (at the appropriate toroidal field), and comparison of co-, counter-current, and push-pull phasing. A beam is used for comparison, later in the shot. Minimal beam blips are used for CER, MSE diagnostics. At each condition, the power threshold for L-H transition is observed for both the rf and for the comparison beam. | ||
| Background: | H-modes with fast wave heating by direct electron absorption as the only form of auxiliary heating were discovered at DIII-D in July 1991, and have not been studied since. In particular, the fast waves in that experiment were launched with the shortest available parallel wavelength ("Pi phasing") at 60 MHz at around 1 T, and we have never studied H-modes with current drive phasing, either co- or counter-current, or at higher frequency than 60 MHz. | ||
| Resource Requirements: | Machine Time:
1 day Experiment Number of gyrotrons: 4 Number of neutral beam sources: 4 | ||
| Diagnostic Requirements: | Profile diagnostics, edge reflectometry. Addition of high time-resolution antenna loading diagnostics would be a plus. | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | Three FW systems, one at 60 MHz and the other two at ~90 MHz. | ||
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