• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.216-226
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• 2015

The neutral beam injection generate ultra-high temperature energy in the tokamak of nuclear fusion. The neutral beam injection make up arc power supply, filament power supply and acceleration & deceleration power supply. The arc power supply has characteristics of low voltage and high current. Arc power supply generate arc through constant output of voltage and current. So this paper proposed suitable buck converter for low voltage and high current. The proposed buck converter used parallel switch because it can be increased capacity and decrease conduction loss. When an arc generated, the neutral beam injection chamber occur high voltage. And it will break output capacitor of buck converter. Therefore the output capacitor was removed in the proposed converter. Thus the proposed converter should be designed for the characteristics of low voltage and high current. Also, the arc power supply should be guaranteed for system stability. The proposed parallel buck converter enables the system stability of the divided low output voltage and high current. The proposed converter with constant output be the most important design of the output inductor. In this paper, designed arc power supply verified operation of system and stability through simulation and prototype. After it is applied to the 288[kW] arc power supply for neutral beam injection.

• 한국진공학회지
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• 제8권4B호
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• pp.556-564
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• 1999

The analysis on heat fluxed on and transmission efficiencies by the collimators of neutral beam injection lines in KSTAR tokamak device has been carried out. And a mathematical model describing non-Gaussian beam distribution profile has been established. A neutral beam injection device is composed of 3 separate ion sources and corresponding beam transport lines, which deal with 7.8 MW of beam power, respectively. The divergence angles of ion beam are $1.2^{\circ}$and $0.5^{\circ}$, in vertical and horizontal directions, respectively. The maximum normal heat load on source exit scraper is 9.1 kW/$\textrm{cm}^2$ and net beam transmission efficiency is ~28%. The effect of misalignment of ion source and scrapers on the scraper heat load and beam transmission also has been analyzed.

• Journal of Astronomy and Space Sciences
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• 제7권2호
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• pp.113-123
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• 1990

전자 beam이 중성 plasma계에 들어왔을 때의 상호작용을 이차원 정전 model을 사용하여 수치계산을 한 결과 beam의 밀도변화에 따라 상호작용이 큰 변화를 보이는 것으로 나타났다. beam 전자의 밀도가 주변 전자의 밀도보다 낮을 때는 많은 양의 beam들이 주변 plasma와의 상호작용을 통해 위상공간에서 vortex 구조를 보이며 입사지역으로부터 멀리 진행할 수 있었던 반면 beam 전자들의 밀도가 높을 때는 대부분의 beam 전자들이 입사지역으로 되돌아오는 희귀전류를 형성하였다. 이 때 자기장의 게기에 따라 전자보다 훨씬 질랴이 큰 ion들이 가속될 수도 있으며 전자들의 전파와 상호작용의 양상이 크게 바뀔 수 있는 것으로 나타났다.

• 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.

• 조명전기설비학회논문지
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• 제27권6호
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• pp.50-58
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• 2013

The Neutral Beam Injection(NBI) generates ultra-high temperature energy in the tokamak of nuclear fusion. The NBI consists of filament power supply acceleration and deceleration power supply and arc power supply(APS). The APS has characteristics of low voltage and high current. APS generate arc through constant output of voltage and current. So this paper proposed suitable buck converter for low voltage and high current. The case of proposed buck converter used parallel switch because it can increase capacity and decrease conduction loss. When an arc is generated, the NBI chamber occur high voltage. And it will break output capacitor of buck converter. Therefore the output capacitor was removed in the proposed converter. Thus buck converter with constant output is the most important design of the output inductor. In this paper, designed APS verified operation of system and stability through simulation and prototype.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.550-551
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• 2013

Large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER plasmas. Negative hydrogen (deuterium) ion sources are major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck- Institute for Plasma Physics, Garching) for ASDEX-U and W7-AS neutral beam injection (NBI) systems. In recent, the first NBI system (NBI-1) has been developed successfully for the KSTAR. The first and second long-pulse ion sources (LPIS-1 and LPIS-2) of NBI-1 system consist of a magnetic bucket plasma generator with multi-pole cusp fields, filament heating structure, and a set of tetrode accelerators with circular apertures. There is a development plan of large-area RF ion source at KAERI to extract the positive ions, which can be used for the second NBI (NBI-2) system of KSTAR, and to extract the negative ions for future fusion devices such as ITER and K-DEMO. The large-area RF ion source consists of a driver region, including a helical antenna (6-turn copper tube with an outer diameter of 6 mm) and a discharge chamber (ceramic and/or quartz tubes with an inner diameter of 200 mm, a height of 150 mm, and a thickness of 8 mm), and an expansion region (magnetic bucket of prototype LPIS in the KAERI). RF power can be transferred up to 10 kW with a fixed frequency of 2 MHz through a matching circuit (auto- and manual-matching apparatus). Argon gas is commonly injected to the initial ignition of RF plasma discharge, and then hydrogen gas instead of argon gas is finally injected for the RF plasma sustainment. The uniformities of plasma density and electron temperature at the lowest area of expansion region (a distance of 300 mm from the driver region) are measured by using two electrostatic probes in the directions of short- and long-dimension of expansion region.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.179.2-179.2
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• 2013

A large-area RF-driven ion source is being developed at Germany for the heating and current drive of ITER device. Negative hydrogen ion sources are major components of neutral beam injection (NBI) systems in future large-scale fusion experiments such as ITER and DEMO. The RF sources for the production of positive hydrogen ions have been successfully developed at IPP (Max-Planck-Institute for Plasma Physics), Garching, for the ASDEX-U and W7-AS neutral beam heating systems. Ion sources of the first NBI system (NBI-1) for the KSTAR tokamak have been developed successfully with a bucket plasma generator based on the filament arc discharge, which have contributed to achieve a good plasma performance such as 15 sec H-mode operation with an injection of 3.5 MW NB power. There is a development plan of RF ion source at the KAERI to extract the positive ions, which can be used for the second NBI system (NBI-2) of the KSTAR and to extract the negative ions for future fusion devices such as Fusion Neutron Source and Korea-DEMO. The development progresses of RF ion source at the KAERI are described in this presentation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.30-31
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• 2010

Filament power supply (FPS) for neutral beam injection (NBI) consists of an insulation type is a device that heats the interior of Tokamak. The input/output specifications of FPS are 3-phase AC 200[Vpeak] and DC16V/300A respectively. A conventional FPS is composed of a 3-phase diode rectifier with DC-link, a H-bridge DC/DC converter, a high frequency transformer, a secondary rectifier and a LC-filter. In this paper, to improve the efficiency of PSFB DC/DC converter it is substituted IGBT devices instead of diode rectifier in secondary side. The proposed method is verified by computer simulation and experiment result.

• 한국진공학회지
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• 제8권4B호
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• pp.548-555
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• 1999

The NBI (Neutral BGeam Injection) System for the Korea Superconducting Tokamak Advanced Research (KSTAR) is composed of ion sources, neutralizers, bending magnets, ion dumps, and calorimeter. The vacuum chamber, in which all of the beam line components are enclosed, is composed of differential pumping system for the effective transfer of the neutral beams. The needed pumping speeds of each of the divided vacuum chamber and the optimized gas flow rate ot the neutralizer were calculated with the help of the particle balance equations. The minimum gas flow rate to the ion sources for producing needed beam current (120kV, 65A, 78MW), the pressure distributions in the vacuum chamber for minimizing re-ionization loss, and the beam loss rate on the beam line components were used as the input in the calculation. Also the scenario for short pulse operation was determined by analysing the time dependent equations. It showed that beam extraction during less than 0.5 sec could be made only with TMP.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1145-1152
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• 2024

To realize an initial objective of the negative ion-based neutral beam injection (N-NBI) at the Comprehensive Research Facility for Fusion Technology (CRAFT) test facility, which targets an H⁰ beam power of 2 MW at an energy of 200-400 keV and a pulse duration of 100 s, it is crucial to study the cesium dynamics of the negative ion source. Here a numerical simulation program CSFC3D is developed and applied to simulate the distribution and time dynamics of cesium during short pulses. The calculations show that most of the cesium on the plasma grid (PG) area originates from the release of cesium that is accumulated within the ion source in the plasma phase. Increasing the wall temperature reduces the loss of cesium on the wall of the ion source. Furthermore, the thickness of the cesium monolayer is directly influenced by the PG temperature. Both simulated and experimental results demonstrate that maintaining the PG temperature between 180 ℃ and 200 ℃ is essential for enhancing the performance of the ion source and optimizing the cesium behavior.