U28+-intensity record applying a H2-gas stripper cell

Abstract

To meet the Facility for Antiproton and Ion Research science requirements higher beam intensity has to be achieved in the present GSI-accelerator complex. For this an advanced upgrade program for the UNILAC is ongoing. Stripping is a key technology for all heavy ion accelerators. For this an extensive research and development program was carried out to optimize for high brilliance heavy ion operation. After upgrade of the supersonic N2-gas jet (2007), implementation of high current foil stripping (2011) and preliminary investigation of H2-gas jet operation (2012), recently (2014) a new H2-gas cell using a pulsed gas regime synchronized with arrival of the beam pulse has been developed. An obviously enhanced stripper gas density as well as a simultaneously reduced gas load for the pumping system result in an increased stripping efficiency, while the beam emittance remains the same. A new record intensity (7.8 emA) for U23828+ beams at 1.4 MeV/u has been achieved applying the pulsed high density H2 stripper target to a high intensity U2384+ beam from the VARIS ion source with a newly developed extraction system. The experimental results are presented in detail.