A cooler for intense low-energy ion beams

A new efficient cooling technique for intense low-energy ion beams is explored. The primary ions are directly injected through a converging-diverging nozzle into a cold expanding supersonic He carrier gas jet. There they adopt the temperature and overall velocity of the gas jet, creating an e(-) He+ plasma in the slowing down process. In the RF-funnel that is placed on axis in the immediate vicinity of the nozzle exit plane the He+ ions and electrons penetrate into the funnel walls and the He+ ions have neutralized, while the desired more heavy ions are confined and focused inside the funnel. After reducing the plasma to a small level in the funnel the ion beam is further purified and compressed passing through a RFQ channel. Finally, the cooled low-emittance ion beam is extracted into high vacuum conditions through the skimmer placed behind the RFQ channel. The operation of the new ion beam cooling technique has been studied by means of numerical simulations. The results of calculations are presented. (C) 2002 Elsevier Science B.V. All rights reserved.