A HIGH POWER TEST FACILITY FOR NEW 201.25 MHZ POWER AMPLIFIERS AND COMPONENTS

A new test facility was designed and constructed at Los Alamos Neutron Science Center (LANSCE) for testing a new Thales TH628 Diacrode final power amplifier and associated driver stages. Anode power requirements for the TH628 are 29 kV DC, with 160 A in millisecond pulses, supplied by a 225 uF capacitor bank with a crowbar circuit to rapidly discharge 88 kJ of stored energy. Charging current was obtained by re-configuring a 2 MW beam power supply remaining from another project. The power tubes are operated with DC anode voltage, and beam pulsing is done with control grid bias switching at relatively low power. A new Fast Protect and Monitor System was designed to take samples of RF reflected power, anode HV, and various tube currents, with logic outputs to promptly remove high voltages, RF drive and beam pulsing during faults. The entire test system is controlled with a programmable logic controller through an operator GUI, for normal startup sequencing and protection against loss of cooling.. This test facility has been used over the past year to test the amplifiers along with high power coaxial components such as hybrid couplers and various water loads.