• Nuclear Engineering and Technology
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• 제55권3호
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• pp.939-946
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• 2023

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.

• 방사선산업학회지
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• 제6권1호
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• pp.101-110
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• 2012

This paper is described the review of several selected accelerators and the use of accelerators in various purposes. The electrostatic accelerators and RF accelerators have been developed before the second world war for the purpose of basic research of physics mainly. RF driven accelerators have been achieved higher energy and applied in medical and industrial use after 1980's. Accelerators have improved incorporating new technologies : axial and horizontal injection, stripping extraction, superconducting RF, computer control, superconducting magnet etc.. Also recent key technologies as BT and NT make the expansion of applications of the accelerators.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.546-551
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• 2024

As an effective methods of plasma heating, neutral beam injection (NBI) systems based on negative hydrogen ion sources will be utilized in future magnetic-confinement nuclear fusion experiments. Because of the collisions between the fast negative ions and the neutral background gas, the positive ions are inevitable created in the acceleration region in the negative NBI system. These positive ions are accelerated back into the ion source and become high energy backstreaming ions. In order to explore the characters of backstreaming ions, the track and power deposition of backstreaming H⁺ beam is estimated using the experimental and simulation methods at NNBI test facility. Results show that the flux of backstreaming positive ions is 1.93 % of that of negative ion extraction from ion source, and the magnet filed in the beam source has an effect on the backstreaming positive ions propagation.

• 센서학회지
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• 제7권3호
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• pp.163-170
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• 1998

플라즈마 이온온도를 측정하기 위해 정전평판형 이온에너지 분석기를 설계 제작하고 에너지 교정 및 에너지 분해능 등의 특성을 조사하였다. 일정한 검출기 위치에서 이온의 에너지에 따른 편향평판전압은 선형성을 보였으며, $53{\sim}103mm$ 사이의 검출기 위치에서 이온에너지에 대한 최대편향평판전압의 기울기는 $1.61{\sim}0.92$로 검출기위치의 증가에 따라 선형적으로 감소하였다. 본 실험 영역에서 에너지 분해능은 약 $4.16{\sim}11.60%$였으며, 검출기 위치 및 이온에너지의 증가에 따라 향상되었다. 상대적 검출효율은 검출기 위치의 증가에 따라 감소하였다. 제작된 분석기를 다목적 플라즈마 발생장치에 설치하여 DC 플라즈마의 이온에너지 스펙트럼을 측정하였다. 방전전압이 320V, 전류가 0.17A인 DC 플라즈마의 이온온도는 $203{\sim}205eV$로 나타났으며 검출기의 위치에 따른 이온온도의 변화는 없었다. 검출기의 위치에 따른 에너지 분해능은 $18{\sim}21%$로 검출기 위치가 증가할수록 향상되었다.