Kinetic modeling of particle dynamics in H− negative ion sources (invited)

Hatayama, A.; Shibata, T.; Nishioka, S.; Ohta, M.; Yasumoto, Masaru; Nishida, Kazuhiro; Yamamoto, Takashi; Miyamoto, K.; Fukano, Azusa; Mizuno, T.

doi:10.1063/1.4852300

Cited by 8 publications

(5 citation statements)

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“…The understanding of H − extraction physics is very important in helping improve the extracted H − beam quality. As has been reviewed in [16], modeling studies with electrostatic particle in cell (ES-PIC) are useful in helping understand the electric potential structure near the extraction aperture and to clarify the process leading to the extraction of H − ion from the source.…”

Section: Introductionmentioning

confidence: 99%

“…chamber wall (anode) and filaments (cathode). In the latter sources, the RF-electromagnetic field is used to generate and heat plasmas.In this review, we mainly focus on the modeling studies, especially the modeling study of H − source plasmas using kinetic approaches, such as the test particle Monte-Carlo model [14] and particle in cell (PIC) model [14,15], which has been reviewed in [16]. Here, we extend it with some new results.…”

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confidence: 99%

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Present status of numerical modeling of hydrogen negative ion source plasmas and its comparison with experiments: Japanese activities and their collaboration with experimental groups

et al. 2018

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The present status of kinetic modeling of particle dynamics in hydrogen negative ion (H − ) source plasmas and their comparisons with experiments are reviewed and discussed with some new results. The main focus is placed on the following topics, which are important for the research and development of H − sources for intense and high-quality H − ion beams: (i) effects of non-equilibrium features of electron energy distribution function on volume and surface H − production, (ii) the origin of the spatial non-uniformity in giant multi-cusp arc-discharge H − sources, (iii) capacitive to inductive (E to H) mode transition in radio frequency-inductively coupled plasma H − sources and (iv) extraction physics of H − ions and beam optics, especially the present understanding of the meniscus formation in strongly electronegative plasmas (so-called ion-ion plasmas) and its effect on beam optics. For these topics, mainly Japanese modeling activities, and their domestic and international collaborations with experimental studies, are introduced with some examples showing how models have been improved and to what extent the modeling studies can presently contribute to improving the source performance. Close collaboration between experimental and modeling activities is indispensable for the validation/improvement of the modeling and its contribution to the source design/development. chamber wall (anode) and filaments (cathode). In the latter sources, the RF-electromagnetic field is used to generate and heat plasmas.In this review, we mainly focus on the modeling studies, especially the modeling study of H − source plasmas using kinetic approaches, such as the test particle Monte-Carlo model [14] and particle in cell (PIC) model [14,15], which has been reviewed in [16]. Here, we extend it with some new results. Close collaboration between the experimental and modeling study is very important as it can improve our basic understanding of source plasmas. Various examples of the model validation will be shown through comparisons with experiments and also how modeling studies contribute to the improvement of source performances.As for the multi-cusp arc-discharge source, we will first show a systematic study to help us understand the role of the EEDF on the H − VP in section 2.2. The study has been carried out for a compact multi-cusp arcdischarge source (SHI H − source: Sumitomo Heavy Industry H − source [17,18]) for medical application such as boron neutron capture therapy and the radioisotope production for molecular imaging technology.The SHI H − source is a typical tandem type H − source [19]. In such a tandem type volume sources, the plasma source volume is divided into two regions by the transverse magnetic field (the so-called magnetic filter filed: MF-field) to control the EEDFs and to promote the two step H − VP reactions explained above. Namely, the source volume consists of two regions: (1) the 'driver region' where the electron energy is high and the EV process is promoted, and (2) the 'extraction region' where the electr...

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Present status of numerical modeling of hydrogen negative ion source plasmas and its comparison with experiments: Japanese activities and their collaboration with experimental groups

et al. 2018

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“…The Electron Energy Distribution Function (EEDF) in space was analyzed using a KEIO-MARC (kinetic model of electrons in ion source with multi-cusp ARC discharge) code [22][23][24][25][26]. KEIO-MARC has been used to estimate the H − production rate in a negative ion source called an SHI H − ion source [27,28] and improve the performance of a JT-60SA negative ion source [29] and for comparison with the results of spectroscopic measurements taken from a QST (National Institute of Quantum and Radiological Science and Technology, Naka, Japan ) 10-ampere ion source [30].…”

Section: Calculation Of Electron Energy Distribution Functionmentioning

confidence: 99%

Spatial Distribution Analyses of Axially Long Plasmas under a Multi-Cusp Magnetic Field Using a Kinetic Particle Simulation Code KEIO-MARC

Nishimura,

Seino,

Yoshimura

et al. 2024

Plasma

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To realize the development of a long plasma source with a uniform electron density distribution in the axial direction, the spatial distribution of plasma under a multi-cusp magnetic field was analyzed using a KEIO-MARC code. Considering a cylindrical plasma source with an axial length of 3000 mm and a cross-sectional diameter of 100 mm, in which the filament electrode was the electron source, the electron density distribution was calculated using the residual magnetic flux density, Bres, and the number of permanent magnets installed at different locations surrounding the device, Nmag, as design parameters. The results show that both Bres and Nmag improved the uniformity of the electron density distribution in the axial direction. The maximum axial electron density decreased with increasing Nmag and increased with increasing Bres. These trends can be explained by considering the nature of the multi-cusp field, where particles are mainly confined to the field-free region (FFR) near the center of the plasma column, and the loss of particles due to radial particle transport. The use of multiple filaments at intervals shorter than the plasma decay length dramatically improved axial uniformity. To further improve axial uniformity, the filament length and FFR must be properly set so that electrons are emitted inside the FFR.

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“…Permanent magnet, multi-dipole cusps have long been used as a plasma confinement mechanism for a diverse set of applications, including hall thrusters, 3 plasma processing machines, 4 neutral beam heating sources, 5,6 and basic plasma physics research experiments. 7 They consist of rings of magnets with alternating ring to ring polarity.…”

Section: Introductionmentioning

confidence: 99%

“…1,21 Advances in numerical simulations have successfully captured some of the physics with kinetic modeling of the electron species but cannot directly simulate the experimental values achieved in the laboratory. 5 Fluid models can be used to capture aspects of the transport but require experimental validation.…”

Section: Introductionmentioning

confidence: 99%

Direct measurement of the plasma loss width in an optimized, high ionization fraction, magnetic multi-dipole ring cusp

et al. 2016

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Kinetic modeling of particle dynamics in H− negative ion sources (invited)

Cited by 8 publications

References 48 publications

Present status of numerical modeling of hydrogen negative ion source plasmas and its comparison with experiments: Japanese activities and their collaboration with experimental groups

Present status of numerical modeling of hydrogen negative ion source plasmas and its comparison with experiments: Japanese activities and their collaboration with experimental groups

Spatial Distribution Analyses of Axially Long Plasmas under a Multi-Cusp Magnetic Field Using a Kinetic Particle Simulation Code KEIO-MARC

Direct measurement of the plasma loss width in an optimized, high ionization fraction, magnetic multi-dipole ring cusp

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