ISS@KEK, Jan. 06 Experimental results in 150MeV proton FFAG M. Aiba (KEK) For KEK FFAG Gr.
Contents • Purpose of 150MeV FFAG project • Machine parameters • COD correction and resonance crossing • Hardware improvement in RF system • Beam extraction with 100Hz operation • Summary
Purpose of 150MeV FFAG • To establish a prototype FFAG for various applications. • Beam extraction from FFAG for the first time • Rapid cycling • Test experiments for applications using extracted beam
COD：Source &Correction scheme • RF cores disturb fringing field. • Additional two dipoles to correct COD.
Resonance crossing (3nx=11) • Horizontal tune changes from ~3.6 to ~3.8 • Characteristics of crossing 3nx=11 • Non structure resonance excited by COD & feed down. • Crossing near injection energy. Injection septum determines horizontal aperture.
Crossing direction dependence Phase space topology with dominant nonlinearlity 〇 （distance from resonance） 1.(a)→(e) “Particle trapping” (Proposed by A.W.Chao & M.Month) 2.(e) →(a) “Emittance growth” (150MeV FFAG)
“Particle trapping” “Emittance growth”
Experiment data Beam intensity during acceleration Black：Suitable dipole correction Red：70% dipole correction Crossing point
Hardware improvement in RF system • Enhancement of RF system: RF voltage: ~5kVpp ~12kVpp Rapid cycling has become possible.
Beam extraction • Fast extraction with kicker and septum • Try to realize 100% extraction efficiency Top and side drawings of the septum magnet
Beam extraction experiment(1) Beam separation with kicker Separated beam with kicker Circulating beam 5mm
Beam extraction experiment(2) Experiment set up
Summary 150MeV proton FFAG has been developed to be a prototype of FFAG for various applications. • COD and resonance crossing has been overcome. • Improvements in RF system to realize rapid cycling. • 100Hz operation was successful. Basic accelerator R&D studies has been completed. Experimentally,