Speaker
Description
A key challenge in particle accelerators is achieving high peak intensity. Space charge effects are strongest at injection and typically limit the achievable peak intensity in a ring. The beam stacking technique can overcome this limitation by accumulating a beam at high energy, where space charge is weaker. It also allows the user cycle and the acceleration cycle to be decoupled. In beam stacking, a bunch of particles is injected and accelerated to high energy. This bunch continues to circulate while a second, and subsequent, bunches are accelerated and merged into the first. Beam stacking with large momentum acceptance is only possible in fixed magnetic field machines with a variable accelerating frequency, such as Fixed Field Alternating Gradient (FFA) accelerators.
This talk presents an experimental demonstration of beam stacking involving two beams at the KURNS FFA facility at Kyoto University, resulting in only a slight increase in the momentum spread of the combined beams. However, the intensity of the first beam was significantly reduced due to RF knockout. This resonance phenomenon has been experimentally confirmed in the ISIS synchrotron at the Rutherford Appleton Laboratory, and two mitigation methods were investigated and will be described here.
