A regime of very high confinement in the boronized DIII-D tokamak
Following boronisation, tokamak discharges in DIII-D have been obtained with confinement times up to a factor of 3.5 above the ITER89-P L-mode scaling and 1.8 times greater than the DIII-D/JET H-mode scaling relation. Very high confinement phases (VH-mode) of 700 ms duration have been observed which are free of edge localised modes (ELMs) or significant sawtoothing activity. The VH-phase is characterised by relatively high central density with n(e)(0) approx. 1 x 1.0 E20/m3, central ion temperatures up to 13.6 keV and central electron temperatures reaching 6 keV at moderate plasma currents (1.6 MA) and heating powers (12.5 - 15.3 MW). These discharges exhibit a low fraction of radiated power (less than or equal to 25%), with Z(eff)(0) close to unity. When compared with standard DIII-D ELM-free H-mode discharges, they also have a higher value of internal inductance and significantly less accumulation of metal impurities in the central region of the discharge.
Bibliographic Reference: Report: GA-A20567 EN (1991) 14 pp.
Availability: Available from General Atomics, P.O. Box 85608, San Diego, CA 92186-9784 (US)
Record Number: 199111641 / Last updated on: 1994-12-02
Original language: en
Available languages: en