DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 332: Comparison of high beta_p small ELM regime in DIII-D and JT-60U | ||
| Name: | Naoyuki Oyama ( |
Affiliation: | JAEA |
| Research Area: | ELM Control & Pedestal Physics | Presentation time: | Not requested | Co-Author(s): | A.Leonard, T. Osborne, Y. Kamada, H. Urano, K. Kamiya |
| Description: | Final goals of this inter-machine experiment are to establish H-mode plasma operation with small ELMs and extension of operational regimes for these small ELM regimes to ITER relevant plasmas. Especially, the effect of the toroidal rotation should be confirmed by using the unique capability of rotation control with co- and counter- NBs in DIII-D and JT-60U. (ITPA inter-machine experiment PEP-17) | ||
| Experimental Approach/Plan: | A search through the extensive DIII-D database of high beta_p discharges did not reveal grassy ELM regime so far. In JT-60U, on the other hand, grassy ELMs with ELM frequency of ~400 Hz was obtained with zero plasma rotation in high q (q95>6) and high delta(d>0.5) plasmas.
Therefore, following experiments will be proposed in DIII-D. 1) The first attempt will be a beta_p scan to reproduce small ELMs in DIII-D following the grassy ELM recipe with balanced NB injection (balanced NB injection + more co NBIs to increase beta) in high q and high delta plasmas. 2) Once we obtain small ELM similar to grassy ELM in DIII-D, parametric dependence of important parameters (delta , q95, beta_p and VT) to enter the grassy ELM regime will be compared between DIII-D and JT-60U. | ||
| Background: | Small ELM regimes have been intensely studied in several devices. The grassy ELM regime discovered by JT-60U is a candidate for a small ELM operation in ITER to combine tolerable ELM energy losses at low pedestal collisionality, and no degradation of pedestal pressure. Since the grassy-like ELMs has been observed in AUG and JET following the grassy ELM prescription developed in JT-60U, we expect that similar small ELM regime can be established also in DIII-D. | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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