Installation and Testing for Commissioning of Normal Conducting RF Linac Segment in the SNS

The Spallation Neutron Source (SNS) linac will deliver a 1.0 GeV proton beam to its accumulator ring. The normal conducting segment of the linac has a radio frequency quadrupole (RFQ), six drift tube linac (DTL) tanks powered by seven 402.5 MHz klystrons and four coupled cavity linac (CCL) modules powered by four 805 MHz klystrons that deliver the 180 MeV beam to the superconducting section of the linac (SCL) that employs eighty one 6-cell cavities powered by eighty-one 805 MHz klystrons. The normal conducting accelerating linac segment has been completely installed in the linac tunnel and successfully conditioned and commissioned. Corresponding high voltage converter modulator (HVCM) and low level RF (LLRF) control systems have been installed and tested.

INTRODUCTION

Figure 1 shows the SNS RF linac with subsystems and the collaborated partner laboratories responsible for them. The front-end system that includes ion source, RFQ and medium energy beam transport (MEBT) systems was delivered by Lawrence Berkeley National Laboratory (LBNL). The high power radio frequency equipment including the DTL and CCL structures was specified, procured and partially tested by Los Alamos National Laboratory (LANL) and then delivered to ORNL for complete installation and testing. Thomas Jefferson Laboratory (JLAB) delivered the SCL structures. The normal conducting segment of the linac has accelerating structures powered with high power klystrons in 1.3 msec 60 Hz pulses: RFQ and DTL tanks powered by seven 2.5 MW, 402.5 MHz klystrons and CCL modules powered by four 5.0 MW, 805 MHz klystrons for delivering the 180 MeV beam to the SCL that employs eighty one 6-cell cavities powered by eighty one 550 kW, 805 MHz klystrons. Figure 1: SNS Linac RF System.