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Design and performance of the LLRF control system for CSNS linac

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The China Spallation Neutron Source (CSNS) linac is designed with beam energy of 80 MeV and a peak current of 15 mA in the first phase. It consists of RFQ, two bunchers of medium-energy beam transmission line, four DTL tanks and one debuncher of linac-to-ring beam transmission line. Correspondingly, eight online RF power sources are used to power these accelerators. In order to stabilize the amplitude, phase and resonant frequency of the RF accelerating field, and minimize beam loss, we have established digital low-level RF (LLRF) control system.


The LLRF system includes RF reference line, analog module (AM), clock distribution module, digital control module (DCM), high-power protection module, timing and RF interlock module and so on. The DCM is mainly responsible for the stability of the RF field amplitude and phase, and RF interlock module can quickly cut off the RF drive in case of arc in the RF transmission system, VSWR over threshold or cavity vacuum fault and so on.


During beam commissioning, all of eight online units of LLRF control system were operating stably and reliably. The amplitude and phase variations of the linac fields have been achieved about ± 0.4% and ± 0.15° with 10-mA beam loading, much better than the design requirements of ± 1% in amplitude and ± 1° in phase.


With the help of this system, we achieved stable operation under different beam loads. Also, many important progresses have been achieved in the LLRF control system for a more convenient operation and a higher stability performance. This article describes the design and implementation of the LLRF for CSNS linac.

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  1. S. Fu, Status of CSNS project, in Proceedings of the 4th International Particle Accelerator Conference (IPAC2013) (2013), pp. 3995–3999

  2. L. Jian, X. Xin’an, M. Zhencheng et al., Linac RF power sources development for China Spallation Neutron Source. High Power Laser Part. Beams 28(8), 085101–085107 (2016)

    Google Scholar 

  3. M. Zhencheng, L. Jian, X. Xin’an et al., Overview of the CSNS LINAC LLRF and operational experiences during beam commissioning, in Proceedings of HB 2016, WEAM2Y01 (2016), pp. 409–412

  4. Z. Yuliang, X. Zhexin, R. Linyan et al., Software development of CSNS linac LLRF remote control system. High Power Laser and Part. Beams 30(11), 115101–115106 (2018)

    Google Scholar 

  5. W. Shuhong, L. Zihua, L. Yingxiong, Proton Linear Accelerator Theory (Atomic Energy Press, Beijing, 1986)

    Google Scholar 

  6. M. Crofford et al., Spallation neutron source LLRF temperature dependence and solution, in Proceeding of the LINAC 2010 (2010), MOP088

  7. H. Ma, SNS LINAC RF control: reference system and phase measurement. SNS LLRF Tech Note 3 (2002)

  8. M. Zhencheng, L. Gang, L. Jian et al., Digital low level RF control system for high intensity proton RFQ accelerator. High Power Laser and Part. Beams 22(2), 433–437 (2010)

    Article  Google Scholar 

  9. Z. Fang, S. Anami, S. Michizono et al., LLRF control system of the J-PARC linac, in Proceedings of LINAC 2008 (2008), pp. 1024–1026

  10. L. Rong, Y. Yao, X. Xu et al., The improvements of LLRF control system for CSNS LINAC. 2013 low-level radio frequency workshop (2013)

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The authors would like to sincerely thank the CSNS linac RF team for their hard work and dedication. This work was supported by the China Spallation Neutron Source project.

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Correspondence to Linyan Rong.

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Rong, L., Mu, Z., Li, J. et al. Design and performance of the LLRF control system for CSNS linac. Radiat Detect Technol Methods 4, 196–202 (2020).

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