Limiter H-mode experiments on TFTR

C. E. Bush, N. L. Bretz, E. D. Fredrickson, K. M. McGuire, R. Nazikian, H. K. Park, J. Schivell, G. Taylor, C. W. Barnes, M. Bitter, R. Budny, Samuel A. Cohen, R. J. Fonck, S. J. Kilpatrick, B. LeBlano, D. M. Manos

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Scopus citations

Abstract

Limiter H-modes with centrally peaked density profiles have been obtained in TFTR using a highly conditioned graphite limiter. The transition to these centrally peaked H-modes takes place from the supershot to the H-mode rather than the usual L- to H-mode transition observed on other tokamaks. Bi-directional beam heating is required to induce the transition. Density peaking factors, ne(0)/〈ne〉, greater than 2.3 are obtained and at the same time the H-mode characteristics are similar to those of limiter H-modes on other tokamaks, while the global confinement, τE, can be > 2.5 times L-mode scaling. The transport analysis of the data shows that transport in these H-modes is similar to that of supershots within the inner 0.6 m core of the plasma, but the stored electron energy (calculated using measured values of Te and ne) is higher for the H-mode at the plasma edge. Microwave scattering data for the edge plasma shows broad spectra at k = 5.5 cm-1 which begin at the drop in Dα radiation and are strongly shifted in the electron diamagnetic drift direction. At the same time, beam emission spectroscopy (BES) shows a coherent mode near the boundary which propagates in the ion direction with m = 15-20 at 20-30 kHz. During an ELM event these apparent rotations cease and Mirnov fluctuations in the frequency range of 50-500 kHz increase in intensity.

Original languageEnglish (US)
Title of host publicationProc 13 Int Conf Plasma Phys Controlled Nucl Fusion Res
PublisherPubl by IAEA
Pages309-323
Number of pages15
ISBN (Print)9201300913
StatePublished - Jan 1 1991

Publication series

NameProc 13 Int Conf Plasma Phys Controlled Nucl Fusion Res

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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    Bush, C. E., Bretz, N. L., Fredrickson, E. D., McGuire, K. M., Nazikian, R., Park, H. K., Schivell, J., Taylor, G., Barnes, C. W., Bitter, M., Budny, R., Cohen, S. A., Fonck, R. J., Kilpatrick, S. J., LeBlano, B., & Manos, D. M. (1991). Limiter H-mode experiments on TFTR. In Proc 13 Int Conf Plasma Phys Controlled Nucl Fusion Res (pp. 309-323). (Proc 13 Int Conf Plasma Phys Controlled Nucl Fusion Res). Publ by IAEA.