Beam commissioning for a superconducting proton linac

To develop the next generation of safe and cleaner nuclear energy, the accelerator-driven subcritical (ADS) system emerges as one of the most attractive technologies. It will be able to transmute the long-lived transuranic radionuclides produced in the reactors of today’s nuclear power plants into shorter-lived ones, and also it will provide positive energy output at the same time. The prototype of the Chinese ADS (C-ADS) proton accelerator comprises two injectors and a 1.5 GeV, 10 mA continuous wave (CW) superconducting main linac. The injector scheme II at the C-ADS demo facility inside the Institute of Modern Physics is a 10 MeV CW superconducting linac with a designed beam current of 10 mA, which includes an ECR ion source, a low-energy beam transport line, a 162.5 MHz radio frequency quadrupole accelerator, a medium-energy beam transport line, and a superconducting half wave resonator accelerator section. This demo facility has been successfully operating with an 11 mA, 2.7 MeV CW beam and a 3.9 mA, 4.3 MeV CW beam at different times and conditions since June 2014. The beam power has reached 28 kW, which is the highest record for the same type of linear accelerators. In this paper, the parameters of the test injector II and the progress of the beam commissioning are reported.

Figure 1

Layout of the C-ADS.

Figure 2

Layout of the C-ADS injector scheme II.

Figure 3

Beam physics design of the C-ADS injector scheme II.

Figure 4

Mechanic drawing of the injector scheme II.

Figure 5

Movable beam measuring platform.

Figure 6

Layout of the LEBT.

Figure 7

Normalized vertical emittance at 85 mm after the LEBT exit.

Figure 8

Commissioning layout of the RFQ.

Figure 9

RFQ acceptance.

Figure 10

RFQ beam current versus energy at different input powers.

Figure 11

Beam energy spread of the RFQ.

Figure 12

The layout of the MEBT and beam diagnostics devices.

Figure 13

Layout of the C-ADS injector scheme II with TCM1.

Figure 14

Emittance simulation and measurements at the MEBT.

Figure 15

Phase scan of the buncher.

Figure 16

Layout of the C-ADS injector scheme II with CM6.

Figure 17

Two times of CW beam operation at 2.7 mA.