Predicting the Toroidal Rotation Profile for ITER

Experiments on DIII-D have increased confidence in a prediction of moderate intrinsic rotation in ITER[1] by investigating the effect of fast-ions and edge neutrals in rotation studies. In a large tokamak like ITER, intrinsic sources of rotation are important because evidence suggests they will be comparable to the neutral beam torque. Measurements of the ρ* dependence of intrinsic rotation in Electron Cyclotron Heated H-modes are consistent with previous measurements of the ρ* scaling of intrinsic torque and momentum confinement in beam heated plasmas with significant fast-ion fractions, showing that fast-ions did not corrupt those results. Also, the small differences in intrinsic rotation of closed and open divertor configurations show that momentum transport due to neutrals in the pedestal is not a significant hidden variable. This result is supported by the similarity of intrinsic rotation before and after the onset of detachment.

[1] C. Chrystal et al., Phys. Plasmas 24, 042501 (2017).