Fast wave current drive in DIII-D

Conference · Wed Feb 01 04:00:00 EST 1995

OSTI ID:25042

Petty, C C; Callis, R W; Chiu, S C; deGrassie, J S; Forest, C B; Freeman, R L; Gohil, P; Harvey, R W; Ikezi, H; Lin-Liu, Y -R ^[1]

---

1. and others

The non-inductive current drive from fast Alfven waves launched by a directional four-element antenna was measured in the DIII-D tokamak. The fast wave frequency (60 MHz) was eight times the deuterium cyclotron frequency at the plasma center. An array of rf pickup loops at several locations around the torus was used to verify the directivity of the four-element antenna. Complete non-inductive current drive was achieved using a combination of fast wave current drive (FWCD) and electron cyclotron current drive (ECCD) in discharges for which the total plasma current was inductively ramped down from 400 to 170 kA. For discharges with steady plasma current, up to 110 kA of FWCD was inferred from an analysis of the loop voltage, with a maximum non-inductive current (FWCD, ECCD, and bootstrap) of 195 out of 310 kA. The FWCD efficiency increased linearly with central electron temperature. For low current discharges, the FWCD efficiency was degraded due to incomplete fast wave damping. The experimental FWCD was found to agree with predictions from the CURRAY ray-tracing code only when a parasitic loss of 4% per pass was included in the modeling along with multiple pass damping.

• Research Organization: General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-89ER51114; W-7405-ENG-48
• OSTI ID: 25042
• Report Number(s): GA-A--21826; CONF-940933--43; ON: DE95007582
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
NON-INDUCTIVE CURRENT DRIVE
PLASMA
TOKAMAK DEVICES