The temperature in the RTP Tokamak under feedback control by regulating the output of a 110-GHz gyrotron

In addition to wave properties like polarization, harmonic number, high- or low-field side launching, and launch angle, absorption of electron cyclotron waves depends strongly, on plasma parameters, such as the temperature . Therefore, we have introduced a new way of operating our 110-GHz gyrotron for electron cyclotron heating and electron cyclotron current-drive experiments. In the Rijnhuizen Tokamak Project (RTP), a system for feedback control of the plasma temperature by regulating the output of the gyrotron has come into operation recently. Other parameters, i.e., the Shafranov parameter Lambda = beta(pol) + l(i)/2 - 1, and the loop voltage can be under feedback control as well. The control system is described and some test results are given.