Recent results of ICRF heating on jet
During ICRF heating experiments, the new four-strap A2 antennas on JET have coupled 16.5 MW of power into single null divertor plasmas (Fig. 1). In combined heating experiments a maximum of 32 MW has been achieved by adding 15 MW of hydrogen minority ICRH to 17 MW of neutral beam injection (NBI). This combined heating power is a record for the present campaign and was achieved in a high density, strongly radiating, reactor-like scenario with {open_quote}grassy{close_quote} ELMs. Central electron temperatures close to 15 keV have been obtained with both RF{emdash}only and combined heating in ELM{emdash}free plasmas which were created with high flux expansion in the divertor region and which were substantially triangular ({delta}{approx_equal}0.3). Similar discharges were used to obtain the highest D-D reactivity in JET with NBI. The addition of hydrogen minority ICRH to these plasmas increases both the reactivity and the H-factor obtained by comparing the thermal energy content to the ITERH93-P scaling. RF-only H-modes have been produced in plasmas with currents ({ital I}{sub {ital p}}) up to 4.7 MA and the power thresholds are similar those with NBI. At {ital I}{sub {ital p}}=4.7 MA and a toroidal field ({ital B}{sub {ital t}}) of 3.2 T, a plasma energy content of 7 MJ was achieved with 8 MW of 51.3 MHz ICRH in 0{pi}0{pi} phasing. The heating efficiency, as determined from power modulation experiments, is close to 100{percent} with 0{pi}0{pi} and 0{pi}{pi}0 phasing. The efficiency decreases for phasings such as 00{pi}{pi} and monopole which produce average values of the parallel wavevector less than 3.5 m{sup {minus}1}. However, the recent introduction of a separator limiter at the center of one antenna has improved its heating efficiency for perpendicularly launched waves and such separators will be fitted to all antennas in the near future. {copyright} {ital 1996 American Institute of Physics.}
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 284113
- Report Number(s):
- CONF-9505105-; ISSN 0094-243X; TRN: 96:021713
- Journal Information:
- AIP Conference Proceedings, Vol. 355, Issue 1; Conference: 11. topical conference on radio frequency in plasmas, Palm Springs, CA (United States), 17-19 May 1995; Other Information: PBD: Feb 1996
- Country of Publication:
- United States
- Language:
- English
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