Multi-machine experiments to study the parametric dependences of momentum transport and intrinsic torque

Momentum transport and plasma rotation have been studied extensively on many tokamaks in recent years. Both experiments and theory have shown that sheared plasma rotation can stabilise turbulence while the rotation itself has beneficial effects on MHD instabilities, such as resistive wall modes. Future tokamaks, like ITER, will have larger moments of inertia and, therefore, less NBI torque per volume and less deep deposition profiles (NBI torque 'dominates' in present large tokamaks over other torque sources). Therefore, intrinsic torque will play a more important role in determining rotation for example in ITER. Numerous experimental results, both on momentum transport and intrinsic torque, have been reported on individual devices - yet only few experimental multi-machine momentum transport or intrinsic torque comparisons have been performed. This paper reports dedicated scans to study momentum transport and intrinsic torque, carried out as dedicated joint experiments on JET, DIII-D, AUG, NSTX and C-Mod within the ITPA framework.