January 21, 2016. The first tank of the Drift Tube Linac (DTL-1) of the China Spallation Neutron Source (CSNS) completed its beam commissioning on January 20th. The beam commissioning lasted for twelve days, and on January 18th, the beam reached the end of the first DTL tank with a peak current of 18 mA at 21.6 MeV, a transmission rate of 100% within the error of the Current Transformer. The success of CSNS DTL-1 is an important milestone of the CSNS project.

The injector of the CSNS accelerator consists of 4 DTL tanks, and it accelerates a H- beam from 3 MeV to 80 MeV.  A lot of work has gone into the top technical challenges on DTL, including high precision manufacturing and installation of the DTL cavity, and manufacturing and tuning of the RF power system.

The success of the CSNS DTL-1 beam commissioning verifies the design and the manufacturing process, and lays a foundation for commissioning the other three DTL tanks.

The beam commissioning was performed using a temporary diagnostic beam line and a removable beam dump. To save commissioning time, beam commissioning of the front end accelerator and Medium Energy Beam transport line was started while the DTL tank was performing RF aging.

On January 9th, the beam reached the end of DTL-1 without acceleration. On January 11th, the first beam was accelerated to the end of DTL-1, with 4 mA at 21.6 MeV. By January 18th, 18 mA/ 21.6 MeV/ 50 ms/ 1 Hz beam was obtained, which exceeds the design goal of 15 mA beam current. It took only 10 days to successfully perform the beam commissioning, which is much quicker than the original plan, as well as beam commissioning of similar accelerators worldwide.