OPERATION OF THE SNS ION SOURCE AT HIGH DUTY-FACTOR

The ion source for the Spallation Neutron Source* (SNS) is a radio frequency, multi-cusp source designed to produce ~ 40 mA of H- with a normalized rms emittance of less than 0.2 pi mm mrad. Once the SNS is fully operational a beam current duty-factor of 6 % (1 ms pulse length, repetition rate of 60 Hz) will be required to inject the accelerator. To date, the source has been utilized in the commissioning of the SNS accelerator and has already demonstrated stable, satisfactory operation at beam currents of ~30 mA with duty-factors of ~0.1 % for operational periods of many weeks. Very little data exists describing source performance at higher duty-factors over sustained run-periods. This report presents the results of four tests, each ~1 week in length, in which the ion source was tuned for maximum beam current and operated at elevated duty-factors in the range of 2-7%