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Quiescent Double Barrier H-Mode Plasmas in the DIII-D Tokamak
| Content Provider | Semantic Scholar |
|---|---|
| Author | Burrell, Keith H. Austin, Max Brennan, Dylan P. Deboo, James Craig Doyle, E. J. Fenzi, Christel Fuchs, C. Gohil, Punit Greenfield, Charles Groebner, Richard J. Lao, Lang L. Luce, Timothy C. Makowski, M. A. Mckee, G. R. Moyer, Richard Alan Petty, Clinton Craig Porkolab, M. Rettig, Curtis Lynn Rhodes, T. L. Rost, J. C. Stallard, Barry W. Synakowski, Edmund John Wade, Michael R. Watkins, J. G. West, William P. |
| Copyright Year | 2000 |
| Abstract | High confinement (H-mode) operation is the choice for next-step tokamak devices based either on conventional or advanced tokamak physics. This choice, however, comes at a significant cost for both the conventional and advanced tokamaks because of the effects of edge localized modes (ELMs). ELMs can produce significant erosion in the divertor and can affect the beta limit and reduced core transport regions needed for advanced tokamak operation. Experimental results from DIII-D [J.L. Luxon, et al., Plasma Phys. and Contr. Nucl. Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987) Vol. I, p. 159] this year have demonstrated a new operating regime, the quiescent H-mode regime, which solves these problems. We have achieved quiescent H-mode operation which is ELM-free and yet has good density and impurity control. In addition, we have demonstrated that an internal transport barrier can be produced and maintained inside the H-mode edge barrier for long periods of time (>3.5 seconds or >25 energy confinement times {tau}{sub E}), yielding a quiescent double barrier regime. By slowly ramping the input power, we have achieved {beta}{sub N} H{sub 89} = 7 for up to 5 times the {tau}{sub E} of 150 ms. The {beta}{sub N} H{sub 89} values of 7 substantially exceed the value of 4 routinely achieved in standard ELMing H-mode. The key factors in creating the quiescent H-mode operation are neutral beam injection in the direction opposite to the plasma current (counter injection) plus cryopumping to reduce the density. Density and impurity control in the quiescent H-mode is possible because of the presence of an edge magnetic hydrodynamic (MHD) oscillation, the edge harmonic oscillation, which enhances the edge particle transport while leaving the energy transport unaffected. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://fusion.gat.com/pubs-ext/presentations/Burrell_UCSD_01.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
