High-intensity Beam Irradiation Research Articles

Performance characteristics of HBC stripper foils irradiated by 650 keV H− and high intensity DC ion beams

Newly developed Hybrid type Boron mixed Carbon (HBC) stripper foils are extensively used not only for the RCS of J-PARC and PSR of LANL, but also for other low energy, high intensity proton accelerators in medical applications. We had before tested HBC stripper foils with 3.2MeV Ne+ and DC heavy ion beams.In order to further understand characteristics of HBC stripper foils, we measured the following parameters using the KEK-650keV H− and light ion Cockcroft Walton DC accelerator: foil lifetime, thickness reduction, uniformity before and after beam irradiation, and foil deformation. Energy deposition in the present experiment was adjusted to a similar level to that of the HBC foil used in the RCS of J-PARC’. In addition, to understand the reason why the HBC stripper foils have high durability against high intensity beam irradiation, we investigated various physical properties, and compared them between the HBC foils and other tested carbon stripper foils.The sizes of the carbon particles in the HBC foil were found to play a vital role in the lifetime.

Development of a highly reproducible mixed ion beam sputtering method for long-lived carbon stripper foils

Heavy ion beam sputtering may be used to prepare carbon stripper foils with long lifetimes, but the breakage rate during foil preparation is very high. Carbon stripper foils have hence been prepared by a heavy ion beam sputtering method with mixed noble gas ions and tested with 3.2 MeV Ne + ions. The mechanical stress and shrinkage under high intensity beam irradiation has been partially overcome by this method, and the lifetime was extended by a factor of about 60 compared with commercially available foils. The average lifetime was 174 mC and the longest lifetime was 252 mC. These foils further showed a low breakage rate during preparation, and were very stable and reproducible.