Toroidal Rotation in JET ICRF Heated H-Mode Plasmas

In present day tokamak experiments, rotation is often driven by the torques of Neutral Beam Injection (NBI), while in an alpha-heated reactor the momentum input is expected to be small. In reactors with high NBI power, the torque is still expected to be small due to the high injection energy needed for the beam to penetrate deep into the plasma, which reduces the torque per MW of injected power. Predicted toroidal rotation velocities for ITER with NBI power of 50MW, around 70km/s in the core and 8kms/s at the edge, are lower than currently observed at JET for the same Prandtl number and with NBI powers less than 20MW. Thus, there has been a growing interest in the intrinsic rotation of the plasma, which is observed to occur in the absence of momentum sources such as NBI. The extrapolation from intrinsic plasma rotation data observed in several machines has suggested that a substantial rotation in the co-current direction, i.e. in the direction parallel to the plasma current, will occur in ITER. In order to contribute to this multimachine intrinsic rotation scaling, referred to as the "Rice scaling", the angular velocity of the plasma column was measured at JET in Ion Cyclotron Resonance Frequency (ICRF) heated H-mode plasmas.
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EFDC100626 1.63 Mb