Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Suppression of stray electrons in the negative ion accelerator of CRAFT NNBI test facility

  • Yuwen Yang (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) ;
  • Jianglong Wei (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) ;
  • Junwei Xie (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) ;
  • Yuming Gu (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) ;
  • Yahong Xie (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) ;
  • Chundong Hu (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences)
  • Received : 2022.08.23
  • Accepted : 2022.12.04
  • Published : 2023.03.25
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Abstract

Comprehensive Research Facility for Fusion Technology (CRAFT) is an integration of different demonstrating or testing facilities, which aim to develop the critical technology or composition system towards the fusion reactor. Due to the importance and challenge of the negative ion based neutral beam injection (NNBI), a NNBI test facility is included in the framework of CRAFT. The initial object of CRAFT NNBI test facility is to obtain a H0 beam power of 2 MW at the energy of 200-400 keV for the pulse duration of 100 s. Inside the negative ion accelerator of NNBI system, the interactions of the negative ions with the background gas and electrodes can generate abundant stray electrons. The stray electrons can be further accelerated and dumped on the electrodes or eject from the accelerator. The stray electrons, including the ejecting electrons, cause the unwanted particle and heat flux onto the electrodes and the inner components of beamline (especially the temperature sensitive cryopump). The suppression of the stray electrons from the CRAFT accelerator is carried out via a series of design and simulation works. The paper focuses the influence of different magnetic field configurations on the stray electrons and the character of the ejecting electrons.

Keywords

Acknowledgement

The authors are very grateful to the other members of the ASIPP NBI team for their continuous support and excellent work. This work was partly supported by the National Natural Science Foundation of China (Contract No. 11975264), and the Comprehensive Research Facility for Fusion Technology Program of China (Contract No. 2018-000052-73-01-001228).

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