Multiple charge beam dynamics in Alternate Phase Focusing structure

Asymmetrical Alternate Phase (A-APF) focusing realized in a sequence of 36 Superconducting Quarter Wave Resonators has been shown to accelerate almost 81 % of input Uranium beam before foil stripper to an energy of 6.2 MeV/u from 1.3 MeV/u. Ten charge states from 34+ to 43+ could be simultaneously accelerated with the phase of resonators tuned for 34+. A-APF structure showed unique nature of large potential bucket for charge states higher than that of tuned one. Steering inherent to QWRs can be mitigated by selecting appropriate phase variation of the APF periods and optimization of solenoid field strengths placed in each of the periods. This mitigation facilitates multiple charge state acceleration schemeComment: 10 pages, 8 figure

Alternate phase focusing in sequence of independent phased resonators as superconducting linac boosters

Theoretical study of an alternate phase focusing (APF) structure, realized in a long chain of double gap quarter wave resonators, capable of accelerating heavy ions from 1.3 to 7  MeV/u has been carried out. Mathieu-Hill stability analysis for the focusing periods consisting of independent resonators with phase variation satisfying square-wave law has been used to evaluate parameters such as the electric field and phase for the resonators. Furthermore, a smooth approximation method taking into account the acceleration in the linac has been employed to find out the rf bucket parameters (energy and phase width acceptance) of the focusing periods. Corroborative particle tracking (longitudinal and transverse) has been carried out using simulated 3D fields for double gap quarter wave resonators (QWR). Steering effects in QWRs over the period have also been studied. In one APF period, the individual phase of resonators changes sign resulting in a vertical steering kick in a particular direction, which is less as compared to the case where all the individual resonators operate in the same phase