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Cristina LA ROCCA (Università di Padova)03/10/2022, 09:20
The tutorial presents the Bo2022 database, a tool that collects - and will continue to collect in the future - Padua's academic population over the eight centuries of its history. The research project BO2022,from which this database was born, began in 2019 and ended in February 2021, and one of its aims was to map the academic population from the foundation of the University of Padua, in 1222,...
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Mamiko SASAO (Office of R&D Promotion, Doshisha University)03/10/2022, 09:50
Fundamental processes related to negative ion formation by
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volume production, surface production, and
double charge exchange production
of different ion species, such as hydrogen, helium, alkali metals, and halogens will be presented, together with their application. -
Dr Martin STOCKLI03/10/2022, 10:20
Martin P. Stockli. Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN37830, USA
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Twenty years ago, there was no ion source that could provide high-currents (>20 mA) of H- beams at high duty factors (>>1%). In addition, the lifetime of H- sources was limited to ~2 Amp-hours. Therefore high-duty-factor H- sources had to be replaced every few weeks! The H- ion sources limited... -
Katsuyoshi TSUMORI03/10/2022, 11:20
Negative ion based NBI (n-NBI) system for the Large Helical Device (LHD) had developed at NIFS since 1987 and started the injection since 1998. Filament-Arc (FA) discharge was applied for the n-NBI system as the first-generation negative ion source. Three beamlines (BL) of the n-NBI system are installed to the LHD and the design values of injection power, beam energy, pulse duration,...
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Vanni TOIGO03/10/2022, 11:50
Efficient and reliable operation of the Heating Neutral Beam Injectors (HNB) is required to achieve thermonuclear-relevant plasma parameters in ITER, a fundamental step on the path towards unlimited sources of clean fusion energy. ITER will be provided with two HNBs, expandable to three, each one expected to inject into the plasma a beam composed of deuterium atoms accelerated up to 1 MeV...
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Pierluigi VELTRI (ITER Organization)03/10/2022, 12:20
The beam divergence is the figure of merit applied to quantify the width of the particle angular distribution as they travel along the beamlines of neutral beam injection (NBI) systems. In the case of the high power neutral beam planned for the ITER experiment, a divergence of less than 7 mrad is mandatory to assure the power level needed for plasma heating in ITER.
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In the last decades, the... -
Dr Jamie ZACKS (ITER Organisation)03/10/2022, 12:50
As with all Neutral Beam injection into tokamaks, the ITER Heating Neutral Beam (HNB) beamline must ensure that the effect of the magnetic field is minimised in order for the pre-neutralised beam to avoid significant deflection which, when later neutralised, will enable it to pass through into the tokamak plasma without damaging the beamline. Due to the strength and range of the ITER magnetic...
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Adrian HEILER03/10/2022, 14:40
Negative hydrogen ion sources for fusion and accelerators predominantly rely on the surface production mechanism. For that, a low work function surface is required to convert incoming hydrogen atoms and ions into negative ions. Due to the so far unsurpassed performance of caesium in this context [1-2], research on caesiated surfaces is unabated. During ion source operation the caesiated...
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Prof. Motoi WADA (Doshisha University)03/10/2022, 15:10
A negative hydrogen (H$^-$) ion source with the plasma excited by 2 MHz radio frequency (RF) power serves as the beam source for the Japan Proton Accelerator Research Complex (J-PARC). We have been studying the H- ion beam intensity modulation at the frequency of plasma excitation RF power since we have found the beam carried the fluctuation at 2 MHz after the RFQ linac [1]. Higher frequency...
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Mr Vinzenz WOLF (AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg, DE)03/10/2022, 15:30
In NNBI ion sources neutral hydrogen atoms and positive ions impact on low work function grid surfaces, where they are converted to negative ions and subsequently extracted. Knowledge and control of the positive ions flux is hence crucial for optimizing the negative ion yield and also for benchmarking numerical models. To this end a Mach probe diagnostic can be used, which determines the...
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Ms Mayuko NISHIWAKI03/10/2022, 15:50
Low work-function materials have been being studied for the use of plasma grids (PG) of negative hydrogen (H-) ion sources to avoid Cs injection to the sources. In the surface H- ion production process, the low work-function of the surface enlarges the survival probability of H- ions leaving from the surface. The work function of the PG can be measured by photoelectric effect, but small...
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Dr David KLEINJAN (Los Alamos National Laboratory)03/10/2022, 16:20
The Los Alamos Neutron Science Center (LANSCE) H- ion source has provided stable output for decades of LANL mission needs, but its maximum beam output has remained the same at ~15 mA. A roadblock to improving beam output has been a lack of thorough understanding of the internal mechanisms of LANSCE H- ion source. The LANSCE H- Ion Source Laser Diagnostic Stand (HLDS) was recently built and...
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Dirk WÜNDERLICH (Max-Planck-Institut für Plasmaphysik)04/10/2022, 08:30
The ELISE test facility with its half ITER-size ion source is an essential part of the European Roadmap towards the ITER NBI system. One aim of ELISE is to demonstrate the ITER target values for the extracted current density, the ratio of co-extracted electrons to extracted ions and the uniformity of the extracted beam during long pulses, i.e. 1000 s in hydrogen and 3600 s in deuterium and at...
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yahong XIE04/10/2022, 09:00
The Comprehensive Research Facility for Fusion Technology (CRAFT) is a large scientific device that is preferentially deployed for the construction of major national science and technology infrastructures. A negative beam source based neutral beam injector (NNBI) with beam energy of 200-400 keV, beam power of 2 MW and beam duration of 100 s is one of the device. A giant radio frequency (RF)...
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Marco BOLDRIN (Consorzio RFX)04/10/2022, 09:30
MITICA, the full scale prototype of ITER Heating Neutral Beam (HNB), is under realization at the Neutral Beam Test Facility (Padova, Italy). MITICA Power Supply is a very complex system, composed of several non-standard equipment, beyond the present industrial standard for insulation voltage level (-1MVdc) and dimensions. Procured by European and Japanese Domestic Agencies, it consists of five...
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Dr Scott LAWRIE (UKRI)04/10/2022, 10:00
A high power, high duty-cycle, negative hydrogen ion source is in development at ISIS. Stable operation of an inductively-coupled plasma pulsing at 50 Hz, 1 ms, 70 kW has been perfected with no apparent lifetime issues. Novel features of the ion source include an external RF-coil, a very low power ignition gun, an adjustable permanent magnet filter field, a water cooling jacket and multiple...
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Dominikus ZIELKE04/10/2022, 10:50
ITER's large and powerful neutral beam injection system is based on a modular concept, where eight cylindrical ’drivers’ are attached to one common expansion and extraction region. In each driver, a plasma is sustained via inductive coupling with powers of up to 100 kW at a driving radio-frequency (RF) of 1 MHz to produce fusion-relevant hydrogen beams. These high powers impose great stress on...
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Marco CAVENAGO (INFN-LNL)04/10/2022, 11:20
Inductive coupling of radiofrequency power to plasma is a complicate process, since it depends from the density of plasma itself for two major reason: (1) ionization is a chain reaction process; (2) with no Faraday screen (as in many sources and until now NIO1), a capacitative coupling may mix with inductive coupling. Several empirical 2D model can be developed, depending on collisional...
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Stefan BRIEFI04/10/2022, 11:50
In H$^–$ ion sources for neutral beam heating applications, the creation of negative ions relies on the surface conversion of H atoms and positive ions at the plasma grid surface. The yield of this process is strongly influenced by the energy of the impacting particles. In general, a higher energy or velocity of H or H$^+_x$ results in a higher conversion rate. However, the velocity of the...
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Katsuyoshi TSUMORI04/10/2022, 12:20
Reduction of beamlet divergence angle is one of the most important targets of negative ion sources driven with Radio-Frequency (RF) to decrease the damages on the accelerator grid and improve the beam injection efficiency. Minimum beamlet divergence of RF driven source is ~12 mrad and is much wider than the divergence accelerated from Filament-Arc (FA) drive sources; required beam divergences...
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Prof. Ursel FANTZ04/10/2022, 14:40
The tutorial gives insights in the need, challenges and ongoing R&D of powerful and large RF-driven ion sources for extracting the required current of negative hydrogen ions (H- and D-) for fusion:
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The neutral beam injection systems for the international fusion experiment ITER (www.iter.org) are based on large negative hydrogen ion sources that have to operate at very ambitious parameters.... -
Haruhisa NAKANO (National Institute for Fusion Science, National Institutes of Natural Sciences)04/10/2022, 15:10
A higher density of the negative ion in front of the plasma beam boundary is important to extract a higher beam current density in the negative hydrogen ion source. Negative ions are mainly produced on the surface of the plasma-facing grid electrode (PG) in cesium seeded negative ion source for fusion. The negative ions are produced from positive ions and atoms impinging to the PG surface by...
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Antonio PIMAZZONI04/10/2022, 15:40
Neutral beams are a valuable option to provide heat and current drive to a magnetically confined plasma. In addition they can be used as a diagnostics for the positive ion temperature and, in case of nuclear fusion reactions, for the amount of helium ash. In the case of ITER, stringent requirements are set on the acceptable beam divergence and aiming in order to propagate such beams up to the...
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engrhyt RATTANAWONGNARA04/10/2022, 16:10
Hydrogen negative-ion source is widely used in the field of high energy particle physics and nuclear fusion science, but the extraction mechanism of hydrogen negative-ion, which is produced at the surface of Plasma Grid (PG) of the source, is not clear. Recent experimental analysis on beam phase-space structure suggests that the non-uniform negative-ion density distribution was formed near...
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Michele FADONE04/10/2022, 17:30
SPIDER (Source for the Production of Ions
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of Deuterium Extracted from a Radio frequency plasma)
is currently in a major shutdown period dedicated to
the upgrade of several components in order to enhance
its performances and guarantee their agreement with
the ITER requirements. During this phase, an indepth inspection of beam source components has been
fundamental to understand SPIDER’s... -
matteo AGOSTINI04/10/2022, 17:35
Biased plasma electrodes in negative ion sources can be used for reducing the amount of co-extracted electrons, together with the magnetic filter field. In SPIDER, both the plasma grid (PG) and the bias plate can be independently polarized with respect to the source body, and this work characterises their effect on the plasma in the expansion region and on the accelerated beam. By increasing...
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Fabio VERONESE (Consorzio RFX)04/10/2022, 17:40
The main purpose of the Divertor Tokamak Test facility (DTT) is to study alternative solutions to mitigate the issue of power exhaust under integrated physics and technical conditions relevant for ITER and DEMO [1]. The proposed system features a Neutral Beam Injector (NBI) heating system, providing deuterium neutrals ($D^0$) with an energy of 510 $keV$ and an injected power of 10 $MW$ to the...
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Dr yongjian XU (institute of plasma physics, chinese academy of science), Ms liping CHEN (institute of plasma physics, chinese academy of science)04/10/2022, 17:45
As a beam diagnostic tool with the highest resolution, the 1D-CFC (one-dimensional carbon fiber composite) calorimeter can obtain the key beam parameters such as beam divergence, beam uniformity. According to the design of accelerating system of ion source for CRAFT NNBI (Comprehensive Research Facility for Fusion Technology Negative Ion based Neural Beam Injection system), the CFC calorimeter...
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Giuseppe CHITARIN (University of Padova and Consorzio RFX)04/10/2022, 17:55
The electrical insulation of the Negative Ion Beam Source at 1 MV is one of the challenging issues of MITICA, the prototype of the Heating Neutral Beam Injector for ITER. A collaborative effort between QST and Consorzio RFX is presently under way for assessing and optimizing this insulation [1]. According to extrapolation models based on recent reduced-scale experiments, the voltage holding...
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Ms Caterina CAVALLINI, Ms Valentina CANDELA04/10/2022, 18:00
SPIDER is the 100 keV full-size Negative Ion Source prototype of the ITER Neutral Beam Injectors and it is operating at Consorzio RFX in Padova, Italy. It represents the most powerful Negative Ion Source in the world. SPIDER works with RF plasma from which Deuterium and/or Hydrogen ions are produced and extracted.
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At the end of 2021, a scheduled long-term shutdown started to perform major... -
Beatrice SEGALINI04/10/2022, 18:05
SPIDER is a radio frequency (RF) driven negative ion source part of the Neutral Beam Test Facility (NBTF), prototype of the negative ion source of ITER’s neutral beam injector. It is composed of $8$ cylindrical drivers, capable of igniting the plasma through the inductive coupling with $4$ radio frequency generators, each delivering up to $200$kW. Its goal is to accelerate $50$A of negative...
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Jia HAN (Université de Lausanne)04/10/2022, 18:10
Negative ion beams are of interest to a wide range of applications. Many previous studies investigated properties of H- or D- with beam diameters on the centimeter scale or larger due to their relevant applications in fusion or accelerators. However, less work has been done with other ion species and beam sizes in the millimeter range or smaller. Such beam properties are particularly important...
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Margherita UGOLETTI, Marco CAVENAGO (INFN-LNL)04/10/2022, 18:15
The compact radiofrequency negative ion source NIO1 (Negative Ion Optimization phase 1) has many available CF40 ports for side views of beamlet matrix. Two kinds of deflecting magnetic systems are present, namely the fringe field of the source filter Bs (mostly directed in vertical direction, x, where z is beam extraction direction) and the electron deflection filter Bd (due to magnets...
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Dr Riccardo AGNELLO (EPFL - Consorzio RFX)04/10/2022, 18:20
The electron density close to the extraction grids and the co-extracted electrons represent a crucial issue when operating negative ion sources for fusion. An excessive electron density in the plasma expansion region can indeed inhibit the negative ion production and introduce potentially harmful electrons in the accelerator. When entering the accelerator, electrons risk overheating the...
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Vincenzo VARIALE (Universita e INFN, Bari (IT))04/10/2022, 18:25
The H- multiaperture ion sources requested by NBI for fusion researches need fair plasma uniformity on those apertures placed on in the so called Plasma Grid, both to facilitate perveance matching of all beamlet and to balance erosion of caesium layer in long pulses. The flow of particle drifts due to both the magnetic filter (Bf), needed in the extraction region to reduce electron density...
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Alastair SHEPHERD04/10/2022, 18:30
For negative ion beam sources there are several methods of measuring the accelerated beam current, namely electrical measurements at the power supply and calorimetric measurements. On SPIDER, the ITER Heating Neutral Beam full-scale beam source, electrical measurements at the acceleration grid power supply (AGPS) are complemented by polarizing the diagnostic calorimeter STRIKE to provide an...
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Daniel LÓPEZ-BRUNA (Laboratorio Nacional de Fusión, CIEMAT)04/10/2022, 18:35
This work documents the initial 3D calculations to simulate the coupling between RF waves and plasma in the plasma sources of the SPIDER device. Axisymmetric 3D calculations in the plasma domain alone compare well against equivalent 2D cases, yielding the expected axi-symmetry with coincident fields and Joule power coupled to the plasma. A model of SPIDER driver, the cylindrical chamber where...
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Roman ZAGORSKI04/10/2022, 18:40
The ITER fusion reactor will be heated by fast neutral beams generated by accelerating and neutralizing negative ions, produced in a RF inductively-coupled plasma and expanding through a region featuring a magnetic filter. Since the beginning of SPIDER operation in 2018, many issues have been solved, lessons learned and objectives reached, but fixing several major problems requires a long...
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Mr Katsuya HAYASHI (Keio University)04/10/2022, 18:45
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). In our previous study [1], it is shown that the plasma meniscus in the negative ion source depends on the H- -electron density ratio as well as the bulk plasma density. Recently, it is pointed out...
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Andrew PAUL04/10/2022, 18:50
University of Victoria; D-Pace, Inc.
Negative ion beams are valuable for applications where tandem accelerators are used for ion injection [1], such as university research centers in the area of surface analysis using RBS (Rutherford Backscattering Spectrometry) and PIXE (Particle Induced X ray Emission) [2] and for high energy, light ion implantation in semiconductor devices [3]. A typical...
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Dr Marco BARBISAN (Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA))04/10/2022, 18:55
Consorzio RFX and INFN-LNL have designed, built and operated the compact radiofrequency negative ion source NIO1 (Negative Ion Optimization phase 1) with the aim of studying the production and acceleration of H- ions. In particular, NIO1 was designed to keep plasma generation and beam extraction continuously active for several hours. Since 2020 the production of negative ions at the plasma...
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Philip JACKLE (Simon Fraser University)04/10/2022, 19:00
Negative Helium ion beams are required for tandem accelerators used at research centers and at implanter facilities. The common production method of such He⁻ beams involve the interaction of a positive Helium ion beam with a low pressure alkali metal vapour. This results in a small portion of He⁺ undergoing two charge exchanges to create the desired He⁻, on the order of a few [ref]. However,...
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Kaushal PANDYA (Institute for Plasma Research)05/10/2022, 08:30
ITER reference design, inductively coupled single driver RF-source ROBIN is operational at
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IPR, Gandhinagar. The first phase of the operation yielded H- ion current density of 22-25
mA/cm2 and with electron to-ion ratios >1. The Cesium (Cs) consumption was very high
compared to a similar source operated at IPP, Garching. The lessons learned from the
operational experience showed the... -
72. Plasma emission monitored via optical emission spectroscopy during the Cs conditioning at SPIDERIsabella MARIO05/10/2022, 09:00
The SPIDER test facility is the full-size ITER neutral beam injector (NBI) ion source, required to provide 355 $\mathrm{A/m^2}$ extracted negative ion current density in hydrogen (285 $\mathrm{A/m^2}$ in deuterium) with an electron-to-ion ratio lower than 0.5 (1 in deuterium). The negative ion source is integrated with a system of three grids, which allows the extraction and acceleration of...
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emanuele SARTORI05/10/2022, 09:20
Three years of experiments on SPIDER allowed characterizing the main features of the source plasma and of the negative ion beam, in the original design configuration. For the large dimensions of the source chamber, and of the extraction area, the investigation of the single-beamlet currents and of the source plasma uniformity had to be carried out to extend the knowledge gained in smaller...
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Min PARK (Korea institute of Fusion Energy (KFE))05/10/2022, 09:50
In Korea, as part of the ITER non-procurement core technology development project, the development of a negative ion beam source is in progress.
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The overall period can be divided into 3 phases corresponding to 3 prototype negative ion beam sources. In the first phase, a Cs-free ion source using 2 MHz RF up to 10 kW was developed. A 4 mm thick water-cooled Faraday shield was inserted inside an... -
Akira UENO05/10/2022, 10:40
In NIBS2020, the stable operation of the J-PARC cesiated RF-driven Hˉ ion source (IS) in a test-stand with a 65 keV 110 mA beam and a beam duty factor of 4.5 % (1 ms x 45 Hz), whose transverse emittances were measured to be suitable for the J-PARC radio-frequency quadrupole LINAC, was reported. In the operation, the beam intensity was limited only by the maximum IS terminal voltage of about 66...
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Dr Weidong CHEN (Institute of High Energy Physics, Chinese Academy of Sciences)05/10/2022, 11:10
The China spallation neutron source project Phase-II (CSNS-II) aims to deliver proton beam of 500 kW on the target. To accomplish this goal, an RF-driven negative hydrogen ion source was developed to replace the penning ion source used in CSNS-I. The RF-driven ion source has been put into commissioning on CSNS accelerator since Sept. 8th of 2021. And it was shut down on July 26th of 2022,...
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Dr Takanori SHIBATA (KEK)05/10/2022, 11:40
In J-PARC (Japan Proton Accelerator Research Complex) center, continuous operation duration of the Radio Frequency (RF) negative hydrogen ($\text{H}^-$) ion source equipped with the internal RF antenna coil is extended step by step in these 6 – 7 years for the goal to supply stable beam during the entire period of J-PARC user operation each year. From Nov. 2020 to Apr. 2021, the continuous ion...
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Jacques LETTRY (CERN)05/10/2022, 12:00
A cesiated RF driven source delivers H- ion that, after stripping at the end of the 160 MeV H- linear injector, provides protons to CERN’s accelerator complex including LHC, where the protons reached a record energy of 6.8 TeV. During initial caesiation, the dual production mechanism of H- ions, via dissociative attachment of electron onto roto-vibrationally excited H2-molecules (volume) and...
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Olli Antero TARVAINEN (STFC Rutherford Appleton Laboratory)05/10/2022, 14:10
We have developed a semi-empirical model predicting the equilibrium caesium coverage (in monolayers) and the resulting work function of the ISIS Penning ion source cathode (in eV) in long pulse operation. We use the caesium balance model to predict the temporal structure of the extracted H$^-$ beam current pulses and compare the model predictions to experimental data with 60 mA, 2 ms beam...
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Mamiko SASAO (Office of R&D Promotion, Doshisha University)05/10/2022, 14:40
Cesium additives are currently used in negative hydrogen(H-/D-) ion sources, which are key components in nuclear fusion plasma heating systems and high energy proton accelerators. Here, a thin cesium layer on a Molybdenum plasma electrode (or plasma grid), PE, lowers the surface work function, and results in high H-/D- production rates. However, in future systems, alternative ion source...
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MARIA RUTIGLIANO (CNR-ISTP (Istituto per la Scienza e Tecnologia dei Plasmi))05/10/2022, 15:10
Caesium-covered molybdenum surfaces are considered for negative ion production [1] [2]. Surface chemical-physics can help to understand the surface process influencing and determining device performances.
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Molecular Dynamics simulations based on ab initio calculations in the framework of DFT( Density Functional Theory) have been used to simulate the interactions occurring at the gas-surface... -
Domenico BRUNO (ISTP - CNR)05/10/2022, 15:40
A roto-vibrational specific corona model is discussed for the simulation of the Fulcher spectrum in low pressure Hydrogen discharges. The model takes into account the processes of electron-impact excitation, spontaneous emission and predissociation and allows to simulate the molecular Fulcher spectrum in the [600:640] nm range.
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The model is applied to the analysis of emission spectra... -
Mark Andrew JOHNSON (Science and Technology Facilities Council - ASTeC)05/10/2022, 16:10
The CERN ALPHA experiment makes precision measurements of antihydrogen atoms held in a superconducting magnetic minimum trap. Recent studies of the antihydrogen spectrum have provided unique tests of fundamental physics, and to improve on these studies ALPHA is now proposing upgrades to directly compare hydrogen and antihydrogen within their existing atom trap. One route towards producing...
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Baoxi HAN05/10/2022, 17:00
The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory is an accelerator-based, short-pulse (sub-μs) neutron production facility for a broad range of scientific applications. A 65-keV H- injector consisting of an rf-driven H- ion source and an electrostatic low energy beam transport section delivers high-current (>50 mA), time-structured (60 Hz, 1.0 ms macro-pulse divided...
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Prof. vadim DUDNIKOV (muons, Inc)05/10/2022, 17:30
H- charge exchange (stripping) injection into the European Spallation Neutron Source (ESS) Storage Ring requires a 90 mA H- ion source that delivers 2.9 ms pulses at 14 Hz repetition rate (duty factor ~4%) that can be extended to 28 Hz (df 8%). This can be achieved with a magnetron surface plasma H- source (SPS) with active cathode and anode cooling. The Brookhaven National Laboratory (BNL)...
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Rob WELTON05/10/2022, 17:50
Abstract. The U.S. Spallation Neutron Source (SNS) is a state-of-the-art neutron scattering facility delivering the world’s most intense pulsed neutron beams to a wide array of instruments which are used to conduct investigations in many fields of science and engineering. Neutrons are produced by spallation of liquid Hg by bombardment of short (~1s), intense (~40A) pulses of protons...
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Martin STOCKLI05/10/2022, 18:20
The SNS H- ion sources deliver the required ~50 mA with practically perfect availability for the entire ~4-months production cycles. The source performance varies from cycle to cycle but the required output current can be easily reached by adjusting the 2 MHz power. However, in about 10 years the SNS H- source is required to deliver routinely ~60 mA for the second target station. While this...
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Taiga GOKA (Tokai university)06/10/2022, 08:30
In fusion devices such as ITER, negative ion based neutral beam injection (NNBI) system is used for plasma heating. Cs-seeded RF driven negative ion source is typical for high-density negative ion production with surface production. However, Cs vapor seeding derived frequent maintenance and it makes long-term operation difficult. Therefore, it is necessary to develop the Cs-free negative ion...
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Roberto PASQUALOTTO (Consorzio RFX)06/10/2022, 08:35
MITICA, the full-size ITER heating neutral beam (HNB) injector prototype, is under construction in the ITER Neutral Beam Test Facility (NBTF) at Consorzio RFX. MITICA is based on an RF negative ion source, producing a 40A deuterium beam accelerated to 1 MeV; the beam is then gas neutralized with 60% efficiency, the residual ions are electrostatically removed, and it is finally dumped on a...
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emanuele SARTORI06/10/2022, 08:40
In negative hydrogen ion sources, the kinetic energy of the atoms is directly related to the negative ion yield at the caesiated converter, with a larger contribution from hot atoms. The H0 energy distribution is related to the formation process: either the kinetic energy release resulting from dissociation of the hydrogen molecules or molecular ions, or the proton neutralization during...
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Ryuichi ONUMA06/10/2022, 08:45
The cesium (Cs)-free negative-ion neutral-beam injection (NNBI) system is technical issue on the development of magnetic fusion reactors. The progress toward realizing a high-performance Cs-free negative-ion source based on volume production in a magnetized sheet plasma device (TPDsheet-U) is reported [1,2]. The volume production of negative hydrogen ions in the produced magnetized sheet...
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Byungkeun NA (Korea Institute of Fusion Energy)06/10/2022, 08:50
A prototype radio frequency (RF) negative hydrogen ion beam source is developed in Korea Institute of Fusion Energy (KFE). The target is to extract negative ion beam with 200 keV, 0.5 A for 100 ms. The RF power supply of 400 kHz delivers over 40 kW to the ICP without the Faraday shield. The plasma is generated and turned off within 120 us, and the RF power supply is stabilized within tens of...
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Ms Silvia CANDELA (INFN, CRF), Ms Valentina CANDELA (INFN, CRF)06/10/2022, 08:55
When we speak about Additive Manufacturing (AM), we think of a rather new manufacturing approach that allows to create objects layer-by-layer and without limits of shape. AM covers a wide range of techniques, that differ from each other by the class of material used for the process, the appearance of the raw material (powder, wire, sheet, etc.) and the way it is added and joined to the...
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Hongyu WU (HUST)06/10/2022, 09:00
Abstract: In particle-in-cell (PIC)simulation, different particle injection method is used to maintain the plasma source term. Common particle injection methods include a) constant flux injection in which a fixed number of ion-electron pairs are injected each time step and b) pair re-injection in which the number of ion-electron pairs injected is according to the number of positive ions...
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Hui LI06/10/2022, 09:05
A fast electrostatic chopper is installed in the low-energy beam transport (LEBT) of China Spallation Neutron Source (CSNS) accelerator. It is used to chop the beam into pulses before RFQ accelerator. The chopped beam pulses synchronize with the period of Rapid Cycling synchrotron (RCS). But the electric field induced by this chopper will destroy the space charge compensation (SCC) in LEBT,...
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Pierluigi VELTRI (ITER Organization)06/10/2022, 09:10
DEMO-FNS facility (R = 3.2m, a = 1m, k = 2, B = 5T) will be a hybrid reactor designed to combine fusion and fission technologies. In a hybrid reactor the power is mainly produced by a fission blanket which is exposed to the neutron flux coming from confined plasma, or a fusion neutron source (FNS). Plasma parameters required for FNS steady-state operation are essentially lower as compared...
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Basile POURADIER DUTEIL06/10/2022, 09:15
SPIDER (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma), hosted at the Neutral Beam Test Facility (NBTF) in Padova, Italy, is the full scale prototype for the ITER Heating Neutral Beam (HNB) source.
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A collisional radiative model for caesium-hydrogen plasmas was recently developed. When used in conjunction with measurements from Optical Emission... -
Marco CAVENAGO (INFN-LNL)06/10/2022, 09:23
NIO1 (Negative Ion Optimization phase 1) is a compact multi-aperture radiofrequency H$^-$ ion source whose design was optimized for sustainable prolonged beam on target (BOT) operation; installation economy implied a drastic scaling as respect to fusion device D$^-$ sources. The latter in a consistent view for energy production request a beam on tokamak (BOT) span of 20 years, that is 6 10$^8$...
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Jacob M BERNER06/10/2022, 09:28
The work function of a surface can be determined by measuring the nA-photocurrents arising from the irradiation by light of different wavelengths. When the chosen photon energies are close to the work function, this energy threshold can be calculated using the Fowler method. As a novelty using fiber coupled LEDs as a light source of sufficient power, the work function inside a negative ion...
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Anna VNUCHENKO (CERN)06/10/2022, 09:33
The caesiated surface negative ion (H) source is the first element of CERN’s LINAC4 a linear injector designed to accelerate negative hydrogen ions to 160MeV. The IS03 ion source, used during Run 3, is operated at 35 mA beam intensity, H⁻ ions are generated via plasma volume and caesiated molybdenum (Cs-Mo) plasma electrode surface mechanisms. The 3D PIC-Monte Carlo ONIX (Orsay Negative Ion...
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Dr Palak JAIN (Consorzio RFX)06/10/2022, 09:38
SPIDER is a full-scale prototype of ITER HNBI radio frequency (RF) negative ion-source equipped with a 100 keV particle accelerator system. It has 4 RF circuits, each composed of an RF generator operating at a frequency of 1 MHz, rated power of 200 kW on 50 Ω load whose RF load is composed of a transmission line feeding a capacitor-based impedance matching network connected to two driver coils...
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Barbara ZANIOL (Consorzio RFX)06/10/2022, 09:43
SPIDER is the prototype source for ITER negative ion beams in operation at Padova PRIMA test facility since 2018. SPIDER mission is to produce an extracted negative ion beam of section 1.5x0.6 m2 and a current density of 355 A/m2 (H-) or 285 A/m2 (D-) while keeping the fraction of co-extracted electrons below 0.5 (H)/1 (D). During the experimental campaigns in SPIDER, the operating conditions...
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Carlo POGGI, emanuele SARTORI (unipd)06/10/2022, 09:48
Neutral Beam Injectors (NBIs) based on negative ions will be the workhorses of the ITER experiment, where they are expected to provide up to 33MW of power to heat the fusion plasma. The negative hydrogen ions are extracted from a RF plasma, in which a magnetic filter field cools down the electrons reaching the so-called expansion region allowing the formation of negative ions near the...
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Margherita UGOLETTI06/10/2022, 09:53
The large size and complexity of ITER negative ion source prototype play a key role in determining the homogeneity of the multi-beamlet negative ion beam current and divergence.
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Visible tomography, which has already proved capable of characterizing the isolated beamlet properties with high temporal and spatial resolutions, can be exploited to study the beam dependence on source parameters... -
Mrs ling YU (institute of plasma physics, chinese academy of science)06/10/2022, 09:58
As one of effective means for plasma heating and current driving, neutral beam injector have been installed in most of nuclear fusion experimental devices in the world. High power neutral beam long pulses are required for continuous heating was required according to the development and research of magnetic controlled fusion energy. Large area high current ion source is the key equipment of...
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Akbar HOSSAIN (University of Jyväskylä)06/10/2022, 10:03
The negative ion formation in the caesium sputter ion sources occurs on the surface of a cathode containing the ionized material. The cathode is covered by a thin layer of caesium (Cs), which lowers the work function of the surface enhancing the negative ion formation. Vogel [1] recently introduced a hypothesis that the negative ion current can be enhanced by exposing the cathode to a laser...
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Dr gwenael FUBIANI (CNRS)07/10/2022, 08:30
In this talk, we will describe in detail the consequences on the negative ion kinetics of the asymmetry in the plasma parameters perpendicular to the magnetic field direction (due to the plasma polarization induced by the Hall current intercepted by the ion source wall). This work is relevant to negative ion sources with a magnetic filter field producing an electron drift directed toward one...
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8. Study of plasma meniscus including the surface produced negative ions by using PIC-MCC simulationKenji MIYAMOTO07/10/2022, 09:00
It is essential to generate the negative ion beams with good beam optics for the negative ion sources. Negative ion beam optics is determined by the shape of the plasma meniscus, which is an ion emitting surface. However, for the electronegative plasma including the surface produced H- ions in the negative ion sources, the key parameters to control the plasma meniscus and the dependence on...
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Prof. Kenichi NAGAOKA (National Institute for Fusion Science)07/10/2022, 09:30
Dynamic responses of negative ion meniscus to externally applied RF field with 2% arc discharge power were investigated experimentally. Three types of responses were identified. First is the beamlet width oscillation with the same frequency as the applied RF field. The second is the oscillation of the beamlet axis. The third is the response of the time-averaged beamlet width. These responses...
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Christian WIMMER (Max-Planck-Inst. f. Plasmaphysik)07/10/2022, 10:00
The BATMAN Upgrade (BUG) test facility at IPP is contributing to the development of RF-driven H$^–$ sources towards the ITER neutral beam injection and beyond. BUG is equipped with an 1/8 size of the ITER NBI ion source and thus is highly flexible for setup changes or diagnostic access. The extraction and acceleration system consists of three grids (plasma grid PG, extraction grid EG and...
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Vincenzo VARIALE (Universita e INFN, Bari (IT))07/10/2022, 10:50
The Neutral Ion Beam Injection will be used to further heat the plasma temperature to reach the ignition of the fusion reaction to producing energy in ITER project and some energy efficiency is required. Recently a very simple beam energy recovery based on space charge effect has been proposed as an alternative to the Electrostatic Ion Dump since had some advantages in removing the residual...
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Shweta SHARMA07/10/2022, 11:20
One of the most significant applications of plasma-based hydrogen negative ion (H-) sources is the production of high current, large area H-beams, which are used for the neural beam injection (NBI) system of a fusion plasma reactor like ITER. Such beams demand high density, uniform plasma (~10^12/cm^3 with variation limited to 10%) with low electron temperature (≤ 1 eV) generated over a large...
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Ms Priti SINGH (Department of Energy Science and Engineering, Indian Institute of Technology Delhi), RAMESH NARAYANAN (Department of Energy Science and Engineering, Indian Institute of Technology Delhi, India)07/10/2022, 11:50
Hydrogen plasma with its multiple constituent species (H, H2 at ground and excited vibrational levels, H+, H2+, H3+, H-) offers a rich array of applications in diverse fields of science and technology such as in materials processing, production of ion beams for fusion plasma heating etc. In the present work, a combination of a solenoid and a set of five permanent ring magnets were used to...
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Mr Akbar HOSSAIN (University of Jyväskylä)07/10/2022, 12:20
The negative ion formation in the cesium sputter ion sources occurs on the surface of a cathode containing the ionized material. The cathode is covered by a thin layer of cesium (Cs), which lowers the work function of the surface enhancing the negative ion formation. Vogel [1] recently introduced a hypothesis that the negative ion current can be enhanced by exposing the cathode to a laser beam...
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Niek DEN HARDER (Max-Planck Institute for Plasma Physics)
The ITER NBI requires H-/D-beamlets with a low divergence, in view of the beamline transmission. Ion extraction and beamlet formation are typically studied with gun-type codes such as IBSimu, which do not treat the plasma explicitly. The beamlet particles are tracked through the full grid system; the compensating charge density in the plasma region is given by an analytical function. As a...
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Valeria CANDELORO
Cusp-shaped magnetic fields are widely used to confine plasmas in various applications. This kind of field topology is obtained by placing a set of permanent magnets with alternate orientation and regular step on the plasma chamber surfaces.
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Within this magnetic field configuration, plasma loss is localised in correspondence of the permanent magnets, where the field lines are perpendicular to...
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