L.J. RYBARCYK, J.D. SCHNEIDER, H.V. SMITH, L.M. YOUNG (LANL), M.E. SCHULZE (GA)
Recently, the Low-Energy Demonstration Accelerator (LEDA) portion of the Accelerator Production of Tritium (APT) project reached its 100-mA, 8-hr CW beam operation milestone. LEDA [1] consists of a 75-keV proton injector [2], 6.7-MeV, 350-MHz cw radio-frequency quadrupole (RFQ) [3] with associated high-power [4] and low-level rf systems, a short high-energy beam transport and high-power (670-kW cw) beam dump. During the commissioning phase it was discovered that the RFQ field level needs to be approximately 5-10% higher than design in order to accelerate the full 100-mA beam with low losses. Upon further investigation, we have observed that the beam transmission for the 100-mA low-duty-factor beam is unexpectedly low for RFQ field levels between 90 and 105% of design. This paper will describe some aspects of LEDA operations critical to achieving the above milestone. Results will also be presented of the measurements and simulations focused on understanding this reduced beam transmission for the RFQ operating at design conditions.
[1] H.V. Smith et al., 'Update On The Commissioning Of The Low-Energy Demonstration Accelerator (LEDA) Radio-Frequency Quadrupole (RFQ),' Proceeding 1999 ICFA Workshop on The Physics of High Brightness Beams, in press
[2] J.D. Sherman et al., 'Status Report on a dc 130-mA, 75-keV Proton Injector,' Rev. Sci. Instrum. 69 (1998) 1003-8.
[3] D. Schrage et al., 'CW RFQ Fabrication and Engineering', Proc. LINAC98 (Chicago, 24-28 August 1998) pp. 679-683.
[4] 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 US Department of Energy
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