Performance of a high current H- radio frequency volume ion source

To evaluate the performance of a high current H- rf-driven volume ion source, the Superconducting Super Collider ion source was modified to accommodate a set of cesium dispensers so that a trace amount of cesium could be introduced into the plasma grid collar. A plasma grid heater element controls the temperature of the cesiated surfaces and the rate of cesium dispensation. With this modification, beam currents in excess of 100 mA and electron to H- current ratios close to one have been observed. In contrast, the uncesiated source provided 30 mA of H- beam with an e/H- ratio ≥25. In both cases the source was operated with a 100 μs beam pulse width at a 10 Hz repetition rate, and an extraction voltage of 35 kV. This cesium enhanced source is a strong candidate for use in high current H- accelerators. copyright 1996 American Institute of Physics