We have developed high-efficiency normal-conducting RF accelerating structures by combining H-mode resonator cavities and a transverse beam focusing by permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. The shunt impedance of inter-digital H-mode (IH-PMQ) structures is 10-20 times higher than that of a conventional drift-tube linac, while the transverse size is 4-5 times smaller. Results of the combined 3-D modeling - electromagnetic computations, multi-particle beam-dynamics simulations with high currents, and thermal-stress analysis - for an IH-PMQ accelerator tank are presented. The accelerating field profile in the tank is tuned to provide the best propagation of a 50-mA deuteron beam using coupled iterations of electromagnetic and beam-dynamics modeling. Measurements of a cold model of the IH-PMQ tank show a good agreement with the calculations. H-PMQ accelerating structures following a short RFQ can be used both in the front end of ion linacs or in stand-alone applications.
@article{arxiv.1104.3807,
title = {H-Mode Accelerating Structures with PMQ Beam Focusing},
author = {Sergey S. Kurennoy and Lawrence J. Rybarcyk and James F. O'Hara and Eric R. Olivas and Thomas P. Wangler},
journal= {arXiv preprint arXiv:1104.3807},
year = {2011}
}
Comments
17 pages, 24 figures; submitted to Phys. Rev. ST-AB