Effect of high energy electrons on H− production and destruction in a high current DC negative ion source for cyclotron

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

doi:10.1063/1.4934846

Cited by 4 publications

(5 citation statements)

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“…As discussed below, the non-equilibrium features of the EEDF are very important for the both volume and surface H − production. [17,18,64,65] Here, we focus on the modeling of Cs-free H − VP. As mentioned in section 1, the H − VP is mainly through the following two step processes, (1) the production of vibrationally excited H 2 (v) molecules (EV process) by fast energetic electrons (E>20 eV), and (2) H − production (DA process) by slow electrons (E<1 eV).…”

Section: Modeling Of Multi-cusp Arc-discharge Sourcesmentioning

confidence: 99%

“…The dependence on other parameters (e.g. arc power P arc , arc current I arc , magnetic filter field strength, B filter ) has been also studied and discussed in detail in [18,64,65]. Figure 1 shows a schematic drawing of the SHI H − source.…”

Section: Compact H − Sources For Medical Applicationsmentioning

confidence: 99%

“…In section 2, modeling studies of multi-cusp arc-discharge H − sources are reviewed. The modeling of the compact tandem type H − sources for medical applications [17,18,64,65] is first discussed with the main attention to the H − VP. Next, the H − SP under the Cs-seeded condition in the so-called 'giant H − ' sources for fusion applications are discussed.…”

Section: Summary and Open Problemsmentioning

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: Modeling Of Multi-cusp Arc-discharge Sourcesmentioning

confidence: 99%

Section: Compact H − Sources For Medical Applicationsmentioning

confidence: 99%

Section: Summary and Open Problemsmentioning

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 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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“…Development of the Negative hydrogen ion (H-) sources is essential due to its wide range of applications, such as a fusion plasma heating [1,2], the medical use [3,4] and the accelerator for the high-energy particle physics [5]. In these applications, the common requirements for development of negative ion sources are to produce the high current negative ion beam with good beam optics and suppress the co-extracted electron current, simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Code-to-code benchmark tests for 3D simulation models dedicated to the extraction region in negative ion sources

Nishioka

Mochalskyy

Taccogna

et al. 2017

AIP Conference Proceedings

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Effect of high energy electrons on H− production and destruction in a high current DC negative ion source for cyclotron

Cited by 4 publications

References 8 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

Code-to-code benchmark tests for 3D simulation models dedicated to the extraction region in negative ion sources

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