[3H08-13] Accelerator, FEL, Laser

[3H11] Effects of external fields and secondary electrons on the space charge compensation in the low energy beam transport line of the high intensity ion accelerator(IFMIF-EVEDA LIPAc).

*Tomonobu Itagaki¹, Ken Takayama², Tomoya Akagi¹, Kai Masuda¹, Nicolas Chauvin³, Luca Bellan⁴, Fabio Cismondi⁵, Hervé Dzitko⁵, Yann Carin⁵ (1. QST, 2. KEK, 3. CEA, 4. INFN-LNL, 5. F4E)

Keywords:Ion beam, Injector, Space charge compensation, LIPAc

In the configuration of Low Energy Beam Transport (LEBT) for the Linear IFMIF Prototype Accelerator (LIPAc), we conducted simulations using the Warp Particle-in-Cell code to investigate the Space Charge Compensation (SCC) effect. This effect arises from electrons originating from residual gas ionization or other sources, which neutralize the space charge of the beam. Our study primarily focuses on analyzing the impact of external fields, created by the electrostatic chopper and the solenoid lenses, on the SCC. Additionally, we examine the role of secondary electrons, produced through beam bombardment of the injector inner walls, in enhancing SCC. This study was conducted over the entire time range in the pulsed operations with using the chopper from the transient state upto the equilibrium state. Our results indicate that the chopping field effectively removes neutralizing electrons in the vicinity of the chopper, with its effective range limited by the solenoids. Notably, the secondary electrons significantly improve the SCC recovery when the chopper is deactivated, contributing to the rapid rise of the beam pulse.