Initial operation of the JET ITER-like High-Power Prototype ICRF Antenna

Fabrication and assembly of a High Power Prototype (HPP) of the JET ITER-like Ion Cyclotron Range of Frequencies (ICRF) launcher have been completed at Oak Ridge National Laboratory (ORNL), and high power tests have begun. The HPP consists of one quadrant of the full 7.5 MW antenna. The prototype is the product of a collaboration between ORNL, Princeton Plasma Physics Laboratory, and EFDA-JET/UKAEA. Internal matching capacitors are utilized in a circuit that maintains a voltage standing wave ratio (VSWR) at the input < 1.5 over a factor of ten range in resistive loading. Short (.05 s) pulses have achieved > 45 kV peak voltage at the internal matching capacitors, which is greater than the original design voltage. High power pulses up to 2s have been run. Diagnostics include thermocouples, voltage probes at the capacitors and along the integral lambda /4 matching transformer, and an optical temperature sensor for in-situ measurements of capacitor temperatures. Low power measurements of electrical characteristics of the antenna have been made and compared with a 3-D electromagnetic model.