Improvement of power handling and operation of the LHCD system on JET

The Lower Hybrid Current Drive (LHCD) system has been in operation since 1994. Its power handling capability and its operation have been increased by improvements and installation of feedback controls on klystron power, launcher position, plasma position, plasma internal inductance, loop voltage and gas introduction. The power is applied during the plasma formation and the current ramp-up, providing a target current profile favourable for high neutron rate performance in shear optimisation experiments. To further the design of a launcher for an ITER relevant system, high and low power tests have been carried out on a module allowing the transmission of a TE/sub 3.0/ mode.