ADS强流质子加速器低能传输段发射度匹配研究

Research of Emittance Matching on the Low Energy Beam Transport Line for ADS Proton LINAC

研制了一套强流质子源及低能传输线(LEBT)注入器用于ADS质子直线加速器。质子源产生35 ke V强流束经过低能传输段聚焦进入射频四极(RFQ)入口。低能传输段不匹配是强流RFQ中引起束流丢失的主要原因。不同加速段的束流匹配是减少束流损失与抑制发射度增长的重要手段。束流损失导致RFQ电极表面受热变形进而引起高频打火,降低RFQ长期运行的稳定性。针对以上问题,研究LEBT发射度在不同的实验条件下如何实现加速器更好的匹配。研究结果表明,LEBT出口束流在35 ke V,10 m A下,束流发射度小于0.2πmm·mrad,当LEBT螺线管电流为210和270 A时,束流在RFQ入口满足匹配条件。

An intense ECR proton source and low energy beam transport(LEBT) system have been developed for the proton Linac of China Initiative Accelerator Driven Sub-Critical system(C-ADS). The proton source can deliver stable 35 ke V proton beams to the entrances of the downstream Radio-Frequency Quadrupole(RFQ).The optics mismatching between the LEBT sections is the main reason that leads to the beam loss in the intense RFQ. Optimum beam matching between the different accelerator sections is one of the key points to reduce the beam losses and emittance growth. For CI-ADS driver Linac system, beam loss at continuous wave operation mode leads to thermal deformation and sparks in the RFQ, and thus has big impact to the reliability of RFQ.Therefore, this paper was mainly studied how to achieve good beam matching and reduce beam losses between LEBT and RFQ. Experiments study show that beam emittance at the LEBT exit is less than 0.2 πmm·mrad when the 10 m A/35 ke V was extracted from the LEBT. The emittance meets the matching requirement of the RFQ entrance when the currents of solenoids lens were sets to 210 and 270 A.