Open Access

Peter Spiller, Lars Bozyk, Patrick Puppel

• n order to reach the de­sired in­ten­si­ties of heavy ion beams for the ex­per­i­ments at FAIR, SIS18 and SIS100 have to be op­er­at­ed with in­ter­me­di­ate charge states. Op­er­a­tion with in­ter­me­di­ate charge state heavy ions at the in­ten­si­ty level of about 1011 ions per cycle has never been demon­strat­ed else­where and re­quires a ded­i­cat­ed up­grade pro­gram for SIS18 and a ded­i­cat­ed ma­chine de­sign for SIS100. The spe­cif­ic prob­lems com­ing along with the in­ter­me­di­ate charge state op­er­a­tion in terms of charge ex­change pro­cess­es at col­li­sions with resid­u­al gas atoms, pres­sure bumps by ion in­duced des­orp­tion and cor­re­spond­ing beam loss ap­pears far below the typ­i­cal space charge lim­its. Thus, new de­sign con­cepts and new tech­ni­cal equip­ment ad­dress­ing these is­sues are de­vel­oped and re­al­ized with high­est pri­or­i­ty. The up­grade pro­gram of SIS18 ad­dress­ing the goal of min­i­mum ion­iza­tion beam loss and sta­ble resid­u­al gas pres­sure con­di­tions has been de­fined in 2005. A major part of this up­grade pro­gram has been suc­cess­ful­ly re­al­ized, with the re­sult of a world record in ac­cel­er­at­ed num­ber of in­ter­me­di­ate charge state heavy ions.