Bunch compression in low emittance pre-injection system of Iranian Light Source Facility

Abstract

In this paper, we introduce the bunch compressor of low emittance Iranian Light Source Facility (ILSF) pre-injection system and discuss on its expected performance by particle tracking. The design and fabrication procedures of the alpha magnet as the main bunch compression component is described. The outcome bunches from the RF electron gun are shortened to 900 fs by the alpha magnet operating at 224 G/cm. The energy spread and total charge of each compressed bunch are 10% and 100 pC respectively. For the electron bunches with low energy spread, less than 1%, further bunch compression is done by the velocity bunching through the first Linac tube. Regardless of the space charge effect and for the case of 98% filtering of the lowest energy electrons with the energy slit inside the alpha magnet, the outcome bunch from the RF gun is firstly compressed to 100 fs by the alpha magnet operating the optimized gradient and then to 30 fs by the first Linac tube. The bunch length will grow to 160 fs after the alpha magnet and to 90 fs after the first Linac tube when the space charge forces are taken into account.