Measurements on H- sources for spallation neutron source application

Lawrence Berkeley National Laboratory is engaged in the development of H- i on sources for the upgrade of the Los Alamos Neutron Science Center (LANSCE ) facility and the spallation neutron source (SNS) to be built in the U.S. For the upgrade of the LANSCE facility, the H- ion generator has to deliver an output current of 40 mA. The repetition rate must be 120 Hz at a pulse length of 1 ms (12% duty factor). Furthermore, the normalized emittance mus t be less than 0.1 pi mm mrad. During the last years, the Ion Beam Technolo gy Group of the LBNL improved the so-called surface conversion source for t he generation of higher H- currents. In the first part of this article, we discuss the operation conditions of the source at the required 40 mA output current. The ion source for the 1 MW spallation neutron source is required to provide 35 mA of H- beam current at 6% duty factor (1 ms pulses at 60 H z) with a normalized rms emittance of less than 0.2 pi mm mrad. The H- beam will be accelerated to 65 keV and matched into a 2.5 MeV RFQ. The ion sour ce is expected to ultimately produce 70 mA of H- at 6% duty factor when the SNS is upgraded to 2 MW of power. For this application, a radio-frequency driven, magnetically filtered multicusp source is being developed at LBNL. Experimental results (including emittance measurements) on the performance of the prototype ion source operated at the demanded beam parameters will b e presented in this article. (C) 2000 American Institute of Physics. [S0034 - 6748(00)54802-3].