Beam Stacking Experiments at TARN

Abstract

TARN is a low energy, around ten MeV/nucleon, ion storage ring aimed at beam accumulation in both the longitudinal and transverse phase spaces from the injector cyclotron. Up to now, proton, H/sub 2//sup +/, ..cap alpha.. and /sup 3/He/sup +/ beams have been stored and the close agreements are shown between the theoretical and experimental results on the beam dynamics. Twenty turn beams are injected in the betatron phase space area of 87 ..pi..mm X mrad by the multiturn injection method and 15 pulses are RF stacked in the momentum space ..delta..p/p of 2.2%. The overall stacking number is then attained at around 300 turns. RF stacking is performed with the repetition rate of 30 Hz and it requires about 0.5 seconds to fill the whole phase spaces with the beam. The e-folding life time of 7 MeV protons is 400 s at the vacuum pressure of 1 X 10/sup -10/ Torr, whereas that of /sup 3/He/sup +/ of the /sup 4/He gas target is 60 ms at 1 x 10/sup -8/ Torr. Collision strengths of charge exchange atomic reactions have been measured.