Linac4 H− ion sources

Lettry, J.; Aguglia, Davide; Alessi, J.; Andersson, Patrik; Bertolo, S.; Briefi, S.; Butterworth, A.; Coutron, Y.; Dallocchio, Alessandro; David, N.; Chaudet, E.; Faircloth, D.; Fantz, U.; Fink, D.; Garlaschè, M.; Grudiev, Alexej; Guida, R.; Hansen, J. D.; Haase, Matthias; Hatayama, A.; Jones, A.; Koszar, I.; Lallement, Jean-Baptiste; Lombardi, A.; Machado, C.; Mastrostefano, C.; Mathot, S.; Mattei, S.; Moyret, P.; Nisbet, D.; Nishida, Kazuhiro; O’Neil, M.; Paoluzzi, M.; Scrivens, R.; Shibata, T.; Steyaert, D.; Thaus, N.; Voulgarakis, G.

doi:10.1063/1.4936120

Cited by 34 publications

(29 citation statements)

References 11 publications

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“…Giant RF-ICP sources for N-NBI plasma heating in fusion applications have been developed [4] and further scale-up is now undertaken for the International Thermonuclear Experimental Reactor N-NBI system [3]. Recent progress in the modeling of such a RF-ICP giant H − source for fusion plasma applications has been reported in [32 and reference therein].In this paper, we focus on a series of the modeling studies in [33][34][35] of the compact RF-ICP H − source for the CERN Linac4 accelerator [8]. In RF-ICP, operation mode is generally classified into two modes [10,13]: in the relatively low density regime, the high voltage across the coil couples to the plasma capacitively (E-mode), while in the relatively high-density regime, the discharge is sustained by the electric field induced by the radio frequency (RF) current in the coil (H-mode).…”

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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 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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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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“…We have simulated the discharge with an Electro Magnetic Particle-In-Cell Monte Carlo Collision (EM-PIC-MCC) code in order to self-consistently take into account spatio-temporal variations of the plasma parameters as well as kinetic e↵ects. The results are compared to photometry measurements performed on the plasma chamber of the Linac4 H ion source at CERN [13]. Our goal is to determine under what conditions the discharge evolves from a low density to the E-H transition and suggest possible optimizations to the magnetic field configuration to achieve optimal power transfer.…”

Section: Introductionmentioning

confidence: 99%

“…Our investigation is carried out on the plasma chamber of the Linac4 H ion source [13], which geometry is shown in figure 1. The hydrogen plasma is formed in a Al 2 O 3 cylindrical chamber with diameter 48 mm and length 136 mm.…”

Section: Geometry and Numerical Modelmentioning

confidence: 99%

Kinetic simulations and photometry measurements of the E-H transition in cylindrical inductively coupled plasmas

Mattei

Nishida

Mochizuki

et al. 2016

Plasma Sources Sci. Technol.

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Abstract.Inductively Coupled Plasmas (ICP) are well known to exhibit two modes of operation: a low density capacitive E-mode and a high density inductive H-mode. In this study we investigate the E-H transition in a cylindrical ICP, and show the e↵ect of an external magnetic cusp field on the transition dynamics. The plasma is simulated by an Electro-Magnetic Particle-In-Cell Monte Carlo Collision code in order to take into account spatio-temporal variations of the plasma dynamics as well as kinetic e↵ects. Simulations are compared to photometry measurements on the Linac4 H ion source plasma chamber. We show that the E-H transition is characterized by strong spatial variations of the plasma parameters, with an axial plasma oscillation in E-mode followed by a centring in the coil region in H-mode. The external magnetic cusp field prevents electrons close to the wall to be accelerated and reduces the inductive power deposition in the plasma. This resulted in a ⇡ 50% higher current to achieve E-H transition compared to the configuration without cusp field. The results indicate possible improvements to the magnetic cusp field configuration in order to achieve optimal power transfer.

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“…The H -ion source (IS03a) described in [4] was successfully operated during the 50 and 105 MeV commissioning runs and provided reliably H -beam intensities of 40 to 50 mA. However, the transmission through the Low Energy Beam Transport (LEBT) section and through the RFQ were below expectation pointing to an H -beam emittance larger than originally simulated [5].…”

Section: Introductionmentioning

confidence: 99%

CERN’s Linac4 cesiated surface H− source

Lettry

Aguglia

Bertolo

et al. 2017

AIP Conference Proceedings

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Abstract.Linac4 cesiated surface H -sources are routinely operated for the commissioning of the CERN's Linac4 and on an ion source test stand. Stable current of 40-50 mA are achieved but the transmission through the LEBT of 80% was below expectations and triggered additional beam simulation and characterization. The H -beam profile is not Gaussian and emittance measurements are larger than simulation. The status of ongoing development work is described; 36 mA H -and 20 mA D -beams were produced with a 5.5 mm aperture cesiated surface ion source. The emittances measured at the test stand are presented. During a preliminary test, the Linac4 proton source delivered a total beam intensity of 70 mA (p, H2 + , H3 + ).

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Linac4 H− ion sources

Cited by 34 publications

References 11 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

Kinetic simulations and photometry measurements of the E-H transition in cylindrical inductively coupled plasmas

CERN’s Linac4 cesiated surface H− source

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