L. M. Young, L. J. Rybarcyk, J. D. Schneider, H. V. Smith (Los Alamos National Laboratory), M. Schultz (General Atomics)
The LEDA RFQ is a 350-MHz continuous-wave (CW) radio-frequency quadrupole (RFQ)[1,2] that has accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV for more than eight hours. The 8-m-long RFQ accepts a dc, 75-keV, ~110-mA H+ beam from the LEDA injector [3] and accelerates it to full energy with ~94% transmission. At design power levels, the peak electrical field on the vane tips is 33 MV/m. However, to achieve high transmission for the 100-mA CW beam, it is necessary to operate the RFQ at field levels ~10% higher than design [4]. The RFQ dissipates 1.5 MW of RF power when operating at this higher field. Three 1.2-MW klystrons provide the 2.2 MW of RF power the RFQ requires to accelerate the 100-mA beam [5]. Output beam power is 670 kW. After reviewing the design innovations that make this RFQ performance possible, we will discuss the major challenges we encountered in pushing the RFQ to this unprecedented power and performance level.
[1] D. Schrage et al., 'CW RFQ Fabrication and Engineering', Proc. LINAC98 (Chicago, 24-28 August 1998) pp. 679-683.
[2] J. D. Schneider, 'Operation of the Low-Energy Demonstration Accelerator: the Proton Injector for APT', Proc. PAC99 (New York, 29 March - 2 April, 1999) pp. 503-507.
[3] J. D. Sherman et al., 'Status Report on a dc 130-mA, 75-keV Proton Injector', Rev. Sci. Instrum. 69 (1998) 1003-8.
[4] L. J. Rybarcyk et al., 'LEDA Beam Operations Milestone and Observed Beam Transmission Characteristics', This conference.
[5] D. E. Rees et al., 'Design, Operation, and Test Results of 350 MHz LEDA RF System', Proc. LINAC98 (Chicago, 24-28 August 1998) pp. 564-566.
* Work supported by the US DOE, Defense Programs. LEDA is the Low-Energy Demonstration Accelerator.
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