Study and optimization of beam transport in a great length recirculation linear accelerator. Application to the ELFE project (Electron Laboratory for Europe)

The transport of three simultaneous beams in the 1 km-length linear accelerator (linac) has been studied, from the beam recombination stage at the linac entry, to their dispersion, at the end of the linac: effects of the injection energy, the FODO mesh length and the mesh betatron propagation at the first passage, on the acceptance corresponding to the three passages, have been simulated. Optics misalignment defects and corrections have been taken into account. It appears that at least one beam position monitor per FODO mesh is necessary. The study was then extended to a two-way recirculation linac. 41 fig., 51 ref