An intense neutron source based on the ⁷Li(p,n)⁷Be reaction is planned as a target in Soreq Applied Research Accelerator Facility (SARAF) for the investigation of s-process nucleosynthesis reactions. The neutrons generated by a proton beam at a laboratory energy of 1912 keV (~30 keV above the threshold energy E_th = 1880 keV), impinging on a thick Li target are forward collimated with angle-integrated energy distribution similar to that of a flux of Maxwellian neutrons at a temperature, kT ≈ 25 keV. An intense proton beam is required in order to generate a high neutron flux which enables measuring new cross sections that are impossible to measure using the traditional techniques. A large effort is presently deployed to replace conventional Van de Graaff accelerators used for production of proton beams with larger-intensity machines (mA to tens of mA), in particular radio-frequency (RF) linear accelerators as well as improving the heat removal abilities of the neutron production targets. High neutron fluxs of 10¹⁰-10¹¹ n/s are expected at SARAF while irradiating a liquid lithium target (LiLiT) with the SARAF high intensity proton beam. The neutron energy spectrum and intensity are sensitive to both the proton average energy and energy spread. The evaluation of the proton beam characteristics expected at SARAF for both high and low intensity is therefore important. Keeping the required neutron spectrum along the irradiation period requires transporting a stable and well characterized high-intensity proton beam to the target position.

Beam dynamics calculations for SARAF phase I proton beam were performed in order to optimize the operational conditions for stellar neutron production. Special care was given for issues and limitations related to the operation of a high intensity RF superconducting linear accelerator and for the transport of a high intensity proton beam. Simulations of low and high intensity proton beam including space charge effects were performed in order to investigate the energy spread limitations at the end of the SARAF linac (σ>4 keV) and at the end of SARAF phase I beamline. Optimization of the beam line magnets was done in order to minimize the losses along the beamline, to control the collimation of the beam by cooled and non-cooled collimators and to focus the beam into a small spot on target with σ≈2 mm.