Frequency Scaling of the Lower-Hybrid-Current-Drive Density Limit in Tokamak Plasmas

Frequency scaling of the lower-hybrid-current-drive density limit in tokamak plasmas.

It is shown experimentally that the lower-hybrid current drive "density limit" is a function of the rf source frequency. While in previous 800MHz experiments this limit occurred at ie = 6 x 1012 cm-3. with a newly installed 2.45GHz, 100kW rf system on the Versator II tokamak fully rf-driven discharges have been achieved at densities up to i = 1.Ox 1013 cm3 , without increasing the toroidal magn...

Co- and Counter-current Rotation Induced by Lower Hybrid Current Drive in Tokamak Plasmas

Effects of magnetic shear on toroidal rotation in tokamak plasmas with lower hybrid current drive.

Application of lower hybrid (LH) current drive in tokamak plasmas can induce both co- and countercurrent directed changes in toroidal rotation, depending on the core q profile. For discharges with q(0) <1, rotation increments in the countercurrent direction are observed. If the LH-driven current is sufficient to suppress sawteeth and increase q(0) above unity, the core toroidal rotation change ...

PUBLISHED VERSION Effects of Magnetic Shear on Toroidal Rotation in Tokamak Plasmas with Lower Hybrid Current Drive

Observation of self-generated flows in tokamak plasmas with lower-hybrid-driven current.

In Alcator C-Mod discharges lower hybrid waves have been shown to induce a countercurrent change in toroidal rotation of up to 60 km/s in the central region of the plasma (r/a approximately <0.4). This modification of the toroidal rotation profile develops on a time scale comparable to the current redistribution time (approximately 100 ms) but longer than the energy and momentum confinement tim...