Numerical modeling of the negative hydrogen ion production in the ion source for cyclotrons

Onai, M.; Etoh, H.; Mattei, S.; Shibata, T.; Aoki, Yasushi; Fujita, S.; Yamada, Shota; Hatayama, A.; Lettry, J.

doi:10.1063/1.4995763

Cited by 5 publications

(2 citation statements)

References 9 publications

(9 reference statements)

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“…The negative hydrogen ion(H − ) sources have various applications, for example, high energy particle physics [1,2], fusion plasma heating [3][4][5][6] and medical applications [7,8]. H − ion sources are required to produce high intensity beams with good convergence for these applications.…”

Section: Introducitonmentioning

confidence: 99%

Numerical study of the plasma meniscus shape and beam optics in RF negative ion sources

Hayashi,

Hoshino,

Miyamoto

et al. 2024

J. Inst.

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In order to extract intense ion beams with good beam optics from hydrogen negative ion sources, it is important to control the shape of the plasma meniscus (i.e. beam emission surface). Recently, it is suggested experimentally that the degradation of beam optics in the RF negative ion sources may be due to the fluctuation of the distance d eff between the meniscus and the extraction grid caused by the fluctuation of the plasma density np . The purpose of this study is to make clear the dependence of d eff on np in the presence of a large amount of surface produced H- ions in order to understand such fluctuation of beam optics in RF sources For the purpose, 3D electrostatic PIC simulation was conducted taking the bulk plasma density as a parameter, investigating the extraction region of a H- ion source. A large amount of the surface H- production on the PG has been taken into account under the assumption that the H- production rate is proportional to the bulk plasma density. The result shows that the effective distance d eff is proportional to np -1/2 even for a large amount of surface H- production. This dependence suggests that the bulk plasma density np is the key parameters to control d eff and the resultant beam optics extracted from the negative ion source.

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Section: Introducitonmentioning

confidence: 99%

Numerical study of the plasma meniscus shape and beam optics in RF negative ion sources

Hayashi,

Hoshino,

Miyamoto

et al. 2024

J. Inst.

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“…Negative hydrogen ion (H -) sources are utilized in a wide range of fields; for example, high energy particle physics [1,2], fusion plasma heating [3][4][5][6], and medical applications [7,8]. Ideally, Hion sources must produce high intensity beams with good convergence.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Produced H<sup>- </sup>Ion on the Plasma Meniscus in Negative Hydrogen Ion Sources

HAYASHI

Hoshino

Hatayama

et al. 2023

Plasma and Fusion Research

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To extract intense ion beams with good beam optics from ion sources, controlling the distance d eff between the plasma meniscus (i.e., beam emission surface) and the beam extraction grid is important. This study conducts a novel investigation into the dependence of the effective distance d eff on the amount of surface Hproduction S H-. For this purpose, a 3D PIC (three dimensional Particle-in-Cell) simulation is conducted to obtain a model geometry of the extraction region for a Hion source with S H-as a parameter. Based on results, d eff significantly depends on S H-and the H --electron density ratio (α = n H -/n e ) in front of the extraction aperture for the same plasma density; as S H-increases, d eff decreases. The results suggest that S H-is critical for controlling d eff and the resultant beam optics extracted from the negative ion source. c

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Effect of Coulomb collision between surface produced H− ions and H+ ions on H− extraction mechanism and beam optics in a Cs-seeded H− ion source by 3D particle in cell model

Nishioka

Abe

Miyamoto

et al. 2018

Journal of Applied Physics

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Recently, in Cs-seeded H− ion sources for fusion applications, the experiments have shown that the surface produced H− ions are mainly extracted from the bulk plasma region, that is, 1–2 cm inside from the beam aperture. The purpose of this paper is to clarify the extraction mechanism of the surface produced H− ions from the bulk plasma region in Cs-seeded H− ion sources for fusion applications by our 3-Dimensional Particle in Cell model for the vicinity of the beam aperture. In the present model, Coulomb collisions between surface produced H− ions and H+ ions (CC H−-H+) are taken into account by the Binary Collision Model. By our model, the trajectories of extracted surface produced H− ions and beam profiles have been investigated for the case with and without CC H−-H+. From the results of trajectories for extracted surface produced H− ions, it has been shown that the surface produced H− ions extracted from the bulk plasma region are drastically increased due to CC H−-H+. Thus, our results have shown that the surface produced H− ions are extracted from the bulk plasma region due to Coulomb collision with H+ ions. Moreover, our results of the beam profiles have shown that CC H−-H+ causes the increase in the beam convergence component. From these results, Coulomb collisions between surface produced H− ions and H+ ions are shown to be very important for the modeling of the extraction mechanism and for the beam optics in Cs-seeded H− ion sources for fusion applications.

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Numerical modeling of the negative hydrogen ion production in the ion source for cyclotrons

Cited by 5 publications

References 9 publications

Numerical study of the plasma meniscus shape and beam optics in RF negative ion sources

Numerical study of the plasma meniscus shape and beam optics in RF negative ion sources

Effect of Surface Produced H<sup>- </sup>Ion on the Plasma Meniscus in Negative Hydrogen Ion Sources

Effect of Coulomb collision between surface produced H− ions and H+ ions on H− extraction mechanism and beam optics in a Cs-seeded H− ion source by 3D particle in cell model

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