Magnetic Configuration And Heating Location Dependences Of Toroidal Torques By Electron Cyclotron Heating In Lhd

Toroidal torque by electron cyclotron heating (ECH) is investigated in the Large Helical Device (LHD) plasmas, assuming the supra-thermal electrons by ECH generate torques on the plasma through j(r) x B and collisions. The j(r) x B torque depends on the radial drift velocity and the fraction of trapped electrons. Therefore, the magnetic configuration and the heating location affects the toroidal torque. We investigate the magnetic configuration and heating location dependences of toroidal torques by ECH in LHD, by considering three typical magnetic configurations: the inward shifted, standard, and outward shifted configurations. As a result, magnetic ripple bottom heating generates larger torque than that of ripple top heating because of the large fraction of trapped electrons. Also, heating at the outer minor radius generates larger toroidal torque than that of heating at the inner radius, and the injection angle can also change the toroidal torque profile. Moreover, ECH generates the largest toroidal torque in the outward shifted configuration. Finally, we evaluate the toroidal flow velocities with the obtained toroidal torques. We obtained the largest flow near the axis in the standard configuration because of its small viscosity and large toroidal torque. (C) 2021 The Japan Society of Plasma Science and Nuclear Fusion Research