ICRF Mode Conversion Flow Drive in JET D(3He) Plasmas and Comparison with Results from Alcator C-Mod

Following a recent Alcator C-Mod experiment on ICRF mode conversion flow drive, we have carried out a similar experiments in JET D(3He) plasmas: Bt0 = 3.45T at R0 = 2.97m, Ip = 2.8 and 1.8MA, central density ne0 ~ 3¥1019 m-3 during flat top, and in L-mode confinement. The plasma current was in the same direction as the toroidal B field. All the plasmas were in D majority with external 3He puffing. The 3He concentration X(3He) nHe3/ne, was feedback controlled in real-time, and scanned pulse by pulse. X(3He) was estimated from visible spectroscopy light in the divertor, linking relative light intensities to relative concentrations. The ICRF power was at 33MHz. At Bt0 = 3.45T, the 3He ion cyclotron resonance layer was about 20cm to the low field side of the magnetic axis. For X(3He) ~ 13%, the D-3He hybrid layer was about 10cm to the high-field-side of the magnetic axis. The ICRF antennas were at -900 phasing, i.e., the launched fast waves were toroidally asymmetric predominantly in the counter-Ip direction. The toroidal angular velocity wf of C6+ is measured by the core CXRS system during beam blips. Pulse No: 78845, counter-Ip rotation (wf < 0) was observed during all the blips for t < 11 sec, and the rotation only became co-Ip later in the pulse with continuous neutral beam injection. A scintillator probe measured the energy and pitch angle of lost fast ions . The detection of 3.7MeV a-particles, born from the nuclear reaction between D and 3He, indicates a hot 3He ion population near the plasma centre.
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