The China Spallation Neutron Source (CSNS) in Dongguan has pushed its beam power past 200 kW and formally put the facility into user operation at that level, twice the beam power it was originally designed for in phase one. The Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences announced the milestone on October 24, saying it was reached on October 20 after nearly a month of beam commissioning.
IHEP called it an important milestone for the second phase of the project, CSNS-II, and a key validation on the way to its 500 kW target.
To limit disruption for users, the CSNS-II team installs upgrade equipment during the facility's annual summer shutdown. This summer it installed and tested the front-end equipment of the linear accelerator, all solid-state modulators and the third magnetic alloy cavity in the rapid cycling synchrotron. With that, all CSNS-II accelerator equipment except the superconducting section is now in place.
Running at higher power made it harder to match hardware and control beam loss, as changes in equipment parameters combined with effects such as space charge and beam impedance instability. The accelerator team tuned key sections of the upgraded linac, including the RFQ and MEBT, and made major changes to the operating mode. IHEP says this resolved collective beam instability and pushed the beam density index above the highest level reported for comparable accelerators worldwide, while beam loss actually fell as power rose.
On the target side, the team installed and tested a new target, T8, on September 25, with a cooling design built for 200 kW and new temperature monitoring for the target plates, which will feed into the design of the CSNS-II high-power target. The facility's 11 neutron instruments open to users were serviced over the summer.
IHEP says the run also gives experience for the next step, raising linac beam energy to 300 MeV. CSNS-II is about halfway through construction; building work was completed at the end of September, and a 1 kW-class 2 K helium refrigerator was installed on October 15. Once finished, the upgrade is meant to give researchers in materials, life sciences and energy a more capable neutron source.
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