Skip to main content

Measurement of emittance at CSNS ion source without analyzing magnet



High current beam is required for CSNS update in future. Over 50 mA H will be designed to deliver to the linac in CSNS II. For the present state of CSNS ion source, the beam emittance cannot satisfy the requirement of RFQ entrance at the 50 mA H beam. In order to improve the beam quality, CSNS ion source is required further improvement.


Simulation shows emittance growth due to the space charge force in the intense H beam when the beam transports through the analyzing magnet. After considering the neutralization of space charge, the emittance growth could be suppressed. The analyzing magnet thus is considered to removed, which might destroy the neutralization of space charge. The beam emittance is measured at the revised CSNS ion source.


Measured results show that beam emittance without the analyzing magnet becomes smaller than that of CSNS ion source. At the requirement of 0.2 πmm mrad, beam current is larger than 30 mA. It reveals that analyzing magnet could destroy space charge neutralization and result in the significant increase of emittance.


Although the results presented are preliminary, it is important to improve the beam quality. This paper details the ion source improvement and measurement process.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5.
Fig. 6
Fig. 7
Fig. 8


  1. J. Wei et al., China spallation neutron source: design, R&D, and outlook. NIMA 600, 10–13 (2009)

    ADS  Article  Google Scholar 

  2. S. Liu, T. Huang et al., Status of CSNS H- ion source. Chin. Phys. C 39, 057008–057011 (2015)

    ADS  Article  Google Scholar 

  3. S. Yamazaki, K. Ikegami et al., Operation and development status of the J-Parc ion source. Rev. Sci. Instrum. 85, 02B136 (2014)

    Article  Google Scholar 

  4. Allison, P., Smith, H. V., Sherman, J. D.: Proceedings of the International Symposium on the Production and neutralization of Negative Ion Beams, New York (1980)

Download references


This work was supported by the Program of National Natural Science Foundation of China Grant No. 11875271

Author information

Authors and Affiliations


Corresponding author

Correspondence to Shengjin Liu.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Liu, S., Lv, Y., Li, F. et al. Measurement of emittance at CSNS ion source without analyzing magnet. Radiat Detect Technol Methods 6, 209–213 (2022).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • CSNS ion source
  • Beam emittance
  • High current pulse beam
  • Analyzing magnet