Spallation Neutron Source High Power RF Installation and Commissioning Progress

The Spallation Neutron Source (SNS) linac will provide a 1 GeV proton beam for injection into the accumulator ring. In the normal conducting (NC) section of this linac, the Radio Frequency Quadupole (RFQ) and six drift tube linac (DTL) tanks are powered by seven 2.5 MW, 402.5 MHz klystrons and the four coupled cavity linac (CCL) cavities are powered by four 5.0 MW, 805 MHz klystrons. Eighty-one 550 kW, 805 MHz klystrons each drive a single cavity in the superconducting (SC) section of the linac. The high power radio frequency (HPRF) equipment was specified and procured by LANL and tested before delivery to ensure a smooth transition from installation to commissioning. Installation of RF equipment to support klystron operation in the 350-meter long klystron gallery started in June 2002. The final klystron was set in place in September 2004. Presently, all RF stations have been installed and high power testing has been completed. This paper reviews the progression of the installation and testing of the HPRF Systems.

RF SYSTEM OVERVIEW

The mission of the RF Group is to ensure that precisely controlled RF power is provided to the linac beam in a safe, highly reliable and cost-effective manner. RF Power Systems provide the pulsed energy to accelerate the H-beam to the accumulator ring. Fourteen High Voltage Converter Modulators (HVCM) supply power to twentyfive klystron transmitters used to control the ninety-two klystrons aligned parallel (figure 1) with the linac from the RFQ to the twenty-third cryomodule. Ninety-two Low Level RF (LLRF) systems, each with a klystron in their control loop, maintain the linac cavities at designed field and amplitude [1]. Four additional, but identical, LLRF systems control the four 20 kW triode amplifiers driving rebuncher cavities between the RFQ and the first DTL.