Lower hybrid current drive experiments on the TdeV tokamak

Current drive experiments have been performed on TdeV over a wide range of parameters. It is found that the current drive efficiency η does not scale with N∥ as expected from simple theory. Simulations with the ACCOME code suggest that the reduced efficiency at low N∥ values is mostly due to a large toroidal upshift in the LH wave spectrum. The loss of suprathermal electrons to the divertor plates was monitored during CD experiments. The power loss increases with decreasing N∥ values and can be reach up to 15% of the injected rf power in low density plasmas.