Beam Energy Spread in FERMI(at)elettra Gun and Linac Induced by Intrabeam Scattering

摘要

Intrabeam scattering (IBS) of electrons in the pre-cathode area in the electron guns know in the literature as Boersh effect is responsible for a growth of the electron beam energy spread there. Albeit most visible within the electron gun where the electron beam density is large and the energy spread is small, the IBS acts all along the entire electron beam pass through the Linac. In this Note we calculate the energy spread induced by IBS in the FERMI(at)elettra gun and also estimate its further growth through the linac up to the Laser Heater area. In our calculations we used actual beam sizes obtained via particle tracking with GPT code for the part of the gun beginning right next to the cathode and up to approximately 5 MeV beam energy and applied Piwinski formalism to obtain energy spread induced by IBS.