A design study on the CSNS LEBT pre-chopper

The China Spallation Neutron Source (CSNS) front end incorporates a pre-chopper in the Low Energy Beam Transport line (LEBT) that will remove a 530 ns section of beam at approximately 1 MHz rate, which is the RF frequency of the ring at injection. It’s one of the most critical devices for properly controlling the injecting beam loss. Physical designing of the pre-chopper is carried out, and the RFQ itself is used as the beam dump of the chopper system. In order to examine the reliability of the pre-chopper design, the beam study of a similar chopper system is successfully performed. The results of physical design and experiments are presented.