Numerical and experimental study of atomic transport and Balmer line intensity in Linac4 negative ion source

Shibata, T.; Mattei, S.; Nishida, Kazuhiro; Lettry, J.; Hatayama, A.

doi:10.1063/1.4916417

Cited by 11 publications

(16 citation statements)

References 7 publications

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“…8 provided a description of the RF-plasma heating process, Shibata et.al 9 calculated the plasma light emission and, across a wide range of plasma conditions, Mochalskyy et. al.…”

Section: Discussionmentioning

confidence: 99%

CERN’s Linac4 H− sources: Status and operational results

Lettry

Aguglia

Alessi

et al. 2015

AIP Conference Proceedings

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“…8 provided a description of the RF-plasma heating process, Shibata et.al 9 calculated the plasma light emission and, across a wide range of plasma conditions, Mochalskyy et. al.…”

Section: Discussionmentioning

confidence: 99%

CERN’s Linac4 H− sources: Status and operational results

Lettry

Aguglia

Alessi

et al. 2015

AIP Conference Proceedings

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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).…”

mentioning

confidence: 99%

“…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). A sharp transition from the E-mode to the H-mode (E-H transition) has been frequently observed in various experiments [13,34,35]. Understanding of the E-H transition is one of the key issues especially for the impedance matching between the RF-system and plasma loading, because the plasma characteristics and the resultant plasma loading impedance significantly change before and after the transition.…”

mentioning

confidence: 99%

“…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%

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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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“…The asymmetric emission is associated with the capacitive coupling driving the plasma. As shown in [26] the line integrated light emission, reconstructed from a collision-radiative model, indicates that the higher peak results from the E-field pushing the electrons towards the view port (figure 6) while the smaller peak to the plasma centred in the plasma chamber ( figure 7). The main contribution to the light intensity is the distance of the photon emission to the view port and the emission roughly scales with the local electron density.…”

Section: Resultsmentioning

confidence: 91%

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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Numerical and experimental study of atomic transport and Balmer line intensity in Linac4 negative ion source

Cited by 11 publications

References 7 publications

CERN’s Linac4 H− sources: Status and operational results

CERN’s Linac4 H− sources: Status and operational results

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

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