Numerical study for beam loss occurring for wide-ranging transverse injection painting and its mitigation scenario in the J-PARC 3-GeV RCS

Hotchi, Hideaki  ; Tani, Norio  ; Watanabe, Yasuhiro  

In the J-PARC 3-GeV Rapid Cycling Synchrotron (RCS), transverse injection painting is utilized to mitigate the space charge induced beam loss. But now the available range of transverse painting is limited to small area due to beta function beating caused by the edge focus of injection bump magnets. This beta function beating additionally excites random betatron resonances through a distortion of the lattice super-periodicity, leading to a deterioration of the betatron motion stability and its resultant decline of the flexibility of transverse painting. For the beta function beating, the correction scheme with pulse-type quadrupole correctors was proposed. The numerical simulation confirmed that this correction scheme effectively mitigates the random betatron resonances by recovering the lattice super-periodicity.