Damage to N-NBI systems due to positive ion back-streaming

Wada, M.; Kondo, Takahiro; Ikeda, K.; Kisaki, M.; Nakano, H.; Tsumori, K.

doi:10.1063/5.0057427

Cited by 4 publications

(1 citation statement)

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“…They could also cause heat loads if they collide on the grids. In particular, the positive ions flowing backwards may damage the source [3,4]. For the efficiency and the safety of the ion source, it is important to evaluate the impacts of the stray particles.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of stripping and stray particles for the one-RF-driver NBI negative ion source prototype of CFETR

Song

Zou

et al. 2022

Plasma Phys. Control. Fusion

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The prototype of negative hydrogen ion source for Neutral Beam Injection (NBI) of China Fusion Engineering Test Reactor (CFETR) is being developed in Southwest Institute of Physics. To study the physics of negative ion beam transport and to optimize the design of the source, the stripping loss and the stray particles’ impacts on the one-RF-driver prototype are analyzed. Collision simulation, including both the beam-gas collisions and the particle-grid collisions, is carried out basing on the results of gas flow evaluation and particle tracing. The stripping loss, the distribution of stray particles and the heat loads are calculated, comparing two configurations of GG (multiaperture or multislot). At the source filling pressure of 0.3 Pa and the vessel pressure 0.05 Pa, the extraction voltage being 8kV and the acceleration voltage 200kV and EG magnet peak of ±45mT, the stripping loss of the 200 A/m2 H- beam can be reduced from 25% to 20% by changing GG from multiapertures to multislots. The H- proportion in the total current at 40 mm after GG, however, shows smaller change than the reduction of the stripping loss possibly because the multislot GG’s larger transparency increases the chance for the stray particles to pass through GG. The total heat load on EG in the two cases with different GG configurations are both around 66 kW, while the GG heat load is reduced from 45 kW for multiapertures to 17 kW for multislots. The study provides good comprehension of the transport process and useful guidance for practical operations.

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Section: Introductionmentioning

confidence: 99%