Electron Cyclotron Heating
Electron Cyclotron Heating (ECH) technology research focuses on the high power microwave sources and transmission lines needed for EC plasma heating. The electron cyclotron frequency (fc = 28 GHz /T) requires microwave sources in the range of 80 to170 GHz. Research is conducted on 110 to 170 GHz gyrotrons that are capable of producing continuous output power at the megawatt level. Research is also conducted on low-loss, corrugated metallic waveguides needed for transmission to the plasma.
A 6 MW, 110 GHz gyrotron system is currently in operation at General Atomics (GA) using gyrotrons built by Communications and Power Industries (CPI) and transmission lines built by GA. The US will supply the transmission lines for the 24 MW ITER ECH system operating at 170 GHz. A test stand for ITER transmission line components is under construction at Oak Ridge National Laboratory (ORNL). Additional research is conducted by universities (MIT, Univ. MD; Univ. WI) and small businesses.
Challenges in ECH technology include increasing the power level of gyrotrons from the megawatt level to the 1.5-2.0 MW range; increasing the efficiency of gyrotrons to over 55%; making frequency tunable gyrotrons for use over a range of operating magnetic fields in the plasma; reducing losses in transmission lines; and developing advanced, efficient solid-state power supplies. Gyrotrons have many spinoff applications, including radar, industrial heating, materials processing and Terahertz spectroscopy.