DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 399: Co-Injected QH-mode access using edge EC/ECCD | ||
| Name: | Phil West ( |
Affiliation: | General Atomics |
| Research Area: | ELM Control & Pedestal Physics | Presentation time: | Not requested | Co-Author(s): | K. Burrell, C. Lasnier, D. Thomas, M. Fenstermacher |
| Description: | Use ECH/ECCD in the region of the pedestal to increase the edge current and decrease the edge density and enhance access to QH-mode in co-injected discharges | ||
| Experimental Approach/Plan: | Work with the RF heating experts to establish a good scenario for edge ECH and ECCD. Establish a strongly pumped, low-density ELMing H-mode in a shape suitable for good edge ECH/ECCD and good pedestal and ELM diagnostics. Tweek the shape and EC aiming to optimize pedestal heating. Do ECH power and location scans. Document the pedestal conditions and ELM properties. Aim the EC power for ECCD and repeat the scans. | ||
| Background: | The ELM-free QH mode is a good candidate for ITER and beyond due to its good confinement properties and the absence of ELMs. The one disadvantage is that is has been observed only in discharges with counter injection. Of the many characteristics of QH-mode that are not typically achieved in co-injected discharges are two are address in this proposal: 1)an enhanced particle transport across the ETB, connected with the EHO and 2) a high edge current density due to low collisionality and high bootstrap drive. ECH has been observed to provide enhance particle transport in the presence of core transport barriers and has been used to reduce density and impurity peaking in these cases. A test of enhancing the particle transport across the ETB is proposed. In addition ECH edge heating can be expected to increase the edge current density by increasing the edge collisionality through both the density decrease and electron heating. Use of ECCD at the edge may further increase the current density. If successful we should be able to bring the co-injected edge plasma closer the hhe conditions observed in counter-injected QH-mode. | ||
| Resource Requirements: | Normal co-injection configuration
Bt and shape adjusted for needs of ECH/ECCD Ip chosen to achieve q95~4.5 6 Beams, including 30L and both 330�??s 4 Gyrotrons (pending ECH modeling) Cryopumping | ||
| Diagnostic Requirements: | Essential:
Thomson CER Edge Reflectometry BES Fast magnetics for ELM delW, EHO SPRED CO2 Interferometry Desired: Li Beam Polarimeter IRTV Bolometry Divertor Tangential TVs | ||
| Analysis Requirements: | Standard ELM and pedestal analysis
Level of detail depends on qualitative success | ||
| Other Requirements: | -- | ||
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