Demonstration of long-pulse acceleration of high power positive ion beam with JT-60 positive ion source in Japan–Korea joint experiment

Kojima, Akira; Hanada, M.; Jeong, Seung Ho; Bae, Y.S.; Chang, Doo-Hee; Kim, T.S.; Lee, K.W.; Park, Min; Jung, Bokyung; Mogaki, K.; Komata, M.; Dairaku, M.; Kashiwagi, M.; Tobari, H.; Watanabe, K.

doi:10.1016/j.fusengdes.2015.11.033

Cited by 4 publications

(2 citation statements)

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“…• The initiating events, which can be internally driven (for example, the mismatch of operating parameters or bad vacuum [11,12]), or externally driven (for example, a failure of control equipment); • The precursor phase events that depends on the specific initiating events (for example, when the ion optical properties are in a non-optimal state, the ion beam bombards the ion source electrode, accumulating a large number of secondary electrons, and the secondary electrons collide with the ion beam [13][14][15][16][17][18]. Figure 3 shows the movement and collision of ions between the electrodes of the ion source); • The events of over current.…”

Section: Introductionmentioning

confidence: 99%

Breakdown prediction of ion source at EAST-NBI using neural network

Wang

Liu

Zhao

et al. 2021

Plasma Phys. Control. Fusion

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The designed neural networks are trained to appraise the risk of ion sources breakdown events in the neutral beam injector (NBI) experimental device using several offline diagnostic signals as inputs. A saliency analysis proves the reasonableness of the chosen inputs, some of which are helpful to improve the network performance. The experimental tests that were carried out refer to data collected from successfully-terminated and breakdown-terminated shots performed during three years of experimental advanced superconducting tokamak NBI experiments, from 2016 to 2019. Results show that it is very possible to develop a predictor base on neural network that intervenes well in advance to avoid ion sources breakdown or mitigate its effects during the beam extraction in the high-power and long-pulse mode.

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Section: Introductionmentioning

confidence: 99%

Breakdown prediction of ion source at EAST-NBI using neural network

Wang

Liu

Zhao

et al. 2021

Plasma Phys. Control. Fusion

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“…During the EAST experiments, NBI-1 has delivered a D 0 beam with the total power of 3.1 MW including 1/2 and 1/3 energy components, using an acceleration voltage of 66 kV. The biggest challenge and the most R&D efforts for the EAST ion source are to extend the pulse duration, which is also a common issue for the neutral beam injectors of the other superconducting fusion devices worldwide, such as LHD [13], KSTAR [14], JT-60SA [15,16], and ITER [17,18]. In this paper, the recent development of some key technologies and the achieved results of the EAST ion source are reported and discussed.…”

Section: Introductionmentioning

confidence: 99%

Key issues for the filament-arc ion source of EAST neutral beam injector toward high-power and long-pulse operation

Wei

Xie

Liu

et al. 2019

Plasma Phys. Control. Fusion

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Neutral beam injection is an effective plasma heating and current drive method for magnetic confinement devices. For supporting the high-confinement plasma operation of the fully superconducting tokamak EAST, a high-power and long-pulse neutral beam is foreseen to be injected into EAST. To achieve such a mission, the most important task is to develop a qualified ion source which can launch a positive ion beam for pulse length up to 100 s with the beam power larger than 2 MW. During the research and development on the EAST positive ion source, several key issues have been studied, including the heat load on electrode grids, the backstreaming electrons deposition, and the gas discharge efficiency. The capability of heat removal of the electrode grids has been demonstrated via a series of simulations and experiments. However, the backstreaming electrons deposition was extremely dense on the electron dump of the ion source, leading to its serious melting damage. According to the simulation of the trajectories of backstreaming electrons, the central magnets on the electron dump were removed as a preliminary solution. The melting damage was successfully avoided without the central magnets and the modified ion source has been operated without malfunction until now. But the total deposition of backstreaming electrons on the electron dump was increased and the magnetic confinement of primary electrons was reduced. Consequently, the arc efficiency was lower and the fraction of the neutral atoms with half beam energy was higher for the modified ion source.

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