Giuseppe Chitarin

Giuseppe Chitarin
University of Padova | UNIPD · Department of Management and Engineering

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180
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Publications

Publications (180)
Article
This topical review gathers the last updates concerning caesium-free negative ion sources presented during the 63rd Course of the International school of Quantum Electronics of the Ettore Majorana Foundation and European collaborative works related to these lectures. Hence, beyond the frame of this course this topical review addresses both theoreti...
Article
It is a widely recognized phenomenon that, in negative ion sources for NBI, the magnetic fields in the source cause an asymmetry of the current density at the meniscus, which affects the beam optics. In order to achieve a more realistic estimation of the negative ion beam optics, the ion current density profile at the beamlet meniscus is sometimes...
Article
To reach fusion conditions and control the plasma configuration in ITER, the next step in tokamak fusion research, two neutral beam injectors (NBIs) will supply 16.5 MW each, by neutralizing accelerated negative hydrogen or deuterium ions. The requirements of ITER NBIs (40A/1 MeV D- ions for ≤1 h, 46A/870 keV H- ions for ≤1000 s) have never been si...
Article
In SPIDER the negative ions are extracted from a plasma generated with RadioFrequency drivers, each fed with a power up to 100 kW at the frequency of 1 MHz. One of its distinguishing characteristics is the source fully installed within a vacuum vessel and operated in the residual gas pressure, including the matching networks for the driver impedanc...
Article
In multi-beamlet negative ion accelerators for neutral beam injectors, the transverse magneticfield necessary for suppressing the co-extracted electrons induces a deflection of the negativeion beamlets that must be corrected. For the design, particle-tracing simulation codes are usedto compute ion trajectories and optical properties of the beamlets...
Article
SPIDER is the prototype of the ion source of the neutral beam injector (NBI) for ITER, and is currently in operation at the Neutral Beam Test Facility (NBTF), Consorzio RFX, Padova, Italy. The magnetic field is important in SPIDER and, in general, in negative ion sources. It is required for filtering the fast electrons in the plasma source (magneti...
Article
The requirements of ITER neutral beam injectors (1 MeV, 40 A negative deuterium ion current for 1 h) have never been simultaneously attained; therefore, a dedicated Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Padova, Italy). The NBTF includes two experiments: SPIDER (Source for the Production of Ions of Deuterium Extracted from R...
Article
Megavolt ITER Injector and Concept Advancement (MITICA) is the full-size prototype of the neutral beam injector (NBI) for the ITER currently under construction at the neutral beam test facility (NBTF) (Consorzio RFX, Padova, Italy). One of the main issues of such a complex machine is to secure a stable voltage holding of the ion source--accelerator...
Article
In the framework of the collaboration between Consorzio RFX (Padova, Italy) and QST (Naka, Japan) two experimental campaigns have been organized on the Negative Ion Test Stand (NITS) in Naka, employing an ITER-like multi-beamlet configuration. These campaigns were aimed at compensating for the undesired magnetic deflection of the ion beam. The expe...
Article
The SPIDER Beam Source (BS), the first prototype of a full scale ion source for the ITER Heating Neutral Beam injector, was delivered to the Neutral Beam Test Facility (NBTF) site in Padova (Italy) after about five years procurement phase. A huge effort was devoted during the procurement for quality controls and testing at the supplier’s workshops....
Article
Complex network theory offers new tools to tackle controllability of systems such as processes affecting generation, extraction and acceleration of negative ions in ion beam sources. A model has therefore been developed and tested for the negative ion beam source NIO1. Preliminary results show good agreement between model predictions and experiment...
Article
To reach fusion conditions and control plasma configuration in ITER, a suitable combination of additional heating and current drive systems is necessary. Among them, two Neutral Beam Injectors (NBI) will provide 33 MW hydrogen/deuterium particles electrostatically accelerated to 1 MeV; efficient gas-cell neutralisation at such beam energy requires...
Conference Paper
In June 2018 the SPIDER device, which is the full-size prototype of the negative ion source and extractor for the ITER Heating Neutral Beam has entered the first operation phase at the Neutral Beam Test Facility (NBTF) in Padova, Italy. This paper describes the present status of the device, the experimental plans and the results obtained during the...
Conference Paper
The high-Q operation of the ITER tokamak will require two Neutral Beam Injectors (NBIs) for plasma heating and current drive. Each beam will be generated by a 40 A current of Deuterium negative ions, accelerated up to the specific energy of 1 MeV and then neutralized. The power delivered to the plasma by each NBI shall reach 16 MW with a duration u...
Conference Paper
During 2016, a joint experimental campaign was carried out by QST and Consorzio RFX on the Negative Ion Test Stand (NITS) at the QST Naka Fusion Institute, Japan, with the purpose of validating some design solutions adopted in MITICA, which is the full-scale prototype of the ITER NBI, presently under construction at Consorzio RFX, Padova, Italy. Th...
Conference Paper
The characterization of the plasma generated by a Hall Effect thruster operating in Nitrogen and Hydrogen is presented. Measurements of the spatial profiles of the electron temperature and density of the plume have been obtained by scanning the region outside the exit plane of the thruster through a Langmuir probe. The measurements are aimed to det...
Conference Paper
The ITER tokamak requires two injectors of neutral beams resulting from the neutralisation of accelerated negative hydrogen/deuterium ions. To optimise the source operation, a specific test facility (“PRIMA”) was established in Padova, comprising the experiment SPIDER (full-size negative ion source with 40A beam, 100keV particle energy). The design...
Conference Paper
Negative ion sources are a key component of neutral beam injection systems, which are used in fusion experiments to raise the plasma parameters to start ignition. A novel concept for a negative ion source based on existing well tested Hall thrusters (HT) is presented. The thruster scheme is modified in order to maximize the hydrogen dissociation so...
Conference Paper
The optics design of the multi-beamlet negative ion accelerator for MITICA has been verified by means of specific experiments in the NITS test facility at the QST lab, employing a scaled-down configuration having the same features as the accelerator of MITICA and ITER HNB. The experiments confirmed the validity of the accelerator design. However it...
Article
High power neutral beam injectors, like those for ITER, must satisfy very demanding parameters (40 A of negative ion current accelerated up to 1 MV for one hour). They are made of various components, which influence each other, so that the global performances eventually require the simultaneous control of several interacting parameters: thus the NB...
Article
NBImag is a code suitable for the design and optimization of complex magnetic field configurations, such as that of a multiaperture, multistage negative ion source and accelerator. The NBImag code has been developed for the design of the ITER neutral beam injector, whose full-size prototype, MITICA, is presently under construction in Padua, Italy....
Article
Full-text available
The 2014–2016 JET results are reviewed in the light of their significance for optimising the ITER research plan for the active and non-active operation. More than 60 h of plasma operation with ITER first wall materials successfully took place since its installation in 2011. New multi-machine scaling of the type I-ELM divertor energy flux density to...
Article
This paper reports the main recent results of the RFX-mod fusion science activity. The RFX-mod device is characterized by a unique flexibility in terms of accessible magnetic configurations. Axisymmetric and helically shaped reversed-field pinch equilibria have been studied, along with tokamak plasmas in a wide range of q(a) regimes (spanning from...
Book
The book, in Italian, presents the fundamentals of Electric Engineering and is devoted to undergratuate non-electric engineering programs
Conference Paper
An innovative magnetic configuration called ADCM (Asymmetric Deflection Compensation Magnets) has been recently proposed for the cancellation of the “criss-cross” deflection of ion trajectories in multi-beamlet negative ion accelerators. Such undesired deflection occurs due to the transverse magnetic field, which is necessary for the suppression of...
Conference Paper
Full-text available
In order to understand the physics mechanism of a negative ion extraction in negative ion sources, an emission surface of the negative ions around an aperture at a plasma grid, so-called a meniscus, has been analyzed by an inverse calculation of the negative ion trajectory in a two dimensional beam analysis code. In this method, the meniscus is def...
Article
Full-text available
The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of the ITER heating neutral beam injector, and SPIDER, the full-size radio frequency negative-ions source. The NBTF realization and the exploitation of SPI...
Article
SPIDER is one of two projects of the ITER Neutral Beam Test Facility under construction in Padova, Italy, at the Consorzio RFX premises. It will have a 100 keV beam source with a full-size prototype of the radiofrequency ion source for the ITER neutral beam injector (NBI) and also, similar to the ITER diagnostic neutral beam, it is designed to oper...
Article
A common problem of the multi-beamlet, negative-ion based Heating Neutral Beam (HNB) Injectors presently used in fusion research, is the undesired deflection of negative ions due the permanent magnets embedded in the Extraction Grid (EG) for the suppression of the unwanted co-extracted electrons. A new solution has been recently developed at Consor...
Article
Full-text available
Neutral beam injection is one of the most important methods of plasma heating in thermonuclear fusion experiments, allowing the attainment of fusion conditions as well as driving the plasma current. Neutral beams are generally produced by electrostatically accelerating ions, which are neutralised before injection into the magnetised plasma. At the...
Article
ITER Neutral Beam Injectors (NBIs) need to be shielded from the relatively strong stray magnetic field generated by the Poloidal Field Coils of the Tokamak. For this reason both the Heating Neutral Beams (HNB) and the Diagnostic Neutral Beam (DNB) will be provided with a Passive Magnetic Shield and with a system of Active Correction and Compensatio...
Article
Full-text available
The heating neutral beam injectors (HNBs) of ITER are designed to deliver 16.7 MW of 1 MeV D⁰ or 0.87 MeV H⁰ to the ITER plasma for up to 3600 s. They will be the most powerful neutral beam (NB) injectors ever, delivering higher energy NBs to the plasma in a tokamak for longer than any previous systems have done. The design of the HNBs is based on...
Article
Neutral beam injectors are among the most important methods of plasma heating in magnetic confinement fusion devices. The propagation of the negative ions, prior to their conversion into neutrals, is of fundamental importance in determining the properties of the beam, such as its aiming and focusing at long-distances, so as to deposit the beam powe...
Article
The physics of the interaction between a liquid metals and an externally applied magnetic field is analysed starting from the basic equations of the phenomena involved: electromagnetic fields, fluid dynamics, viscosity and surface tension. A set of general equations is deduced to describe a levitation melting system. The equations are progressively...
Article
Substantial progresses have been achieved in the realization of the ITER Neutral Beam Test Facility (NBTF) hosted in Padova, Italy; the buildings, completed by the end of 2015, are being progressively filled with new systems and components. The realization of SPIDER, the ITER full-size negative ion source, is well advanced and important progress is...
Article
Full-text available
The development of the NBI systems for ITER requires unprecedented parameters (40 A of negative ion current accelerated up to 1 MV for one hour) so that a test facility is in the final phase of construction at Consorzio RFX (Padova, Italy), housing two experiments. A full-size negative ion source, SPIDER, aims at demonstrating the creation and extr...
Article
The heating neutral beam (HNB) systems at ITER are designed to inject a total of 33 MW of either 1 MeV D<sup>0</sup> or 870 keV H<sup>0</sup> beams into the ITER plasma using two injectors with a possible addition of a third injector later to increase the injected power to ~50 MW. The injectors operate in a radioactive environment and should surviv...
Article
Full-text available
The megavolt ITER injector and concept advancement experiment is the prototype and the test bed of the ITER heating and current drive neutral beam injectors, currently in the final design phase, in view of the installation in Padova Research on Injector Megavolt Accelerated facility in Padova, Italy. The beam source is the key component of the syst...
Article
The negative-ion accelerator for the MITICA neutral beam injector has been designed and optimized in order to reduce the thermo-mechanical stresses in all components below limits compatible with the required fatigue life. However, deviation from the expected beam performances can be caused by "off-normal" operating conditions of the accelerator. Th...
Article
In view of the realization of the negative ion beam injectors for ITER, a test facility, named SPIDER, is under construction in Padova (Italy) to study and optimize production and extraction of negative ions. The present paper is devoted to the analysis of the expected first operations of SPIDER in terms of single-beamlet and multiple-beamlet simul...
Article
SPIDER (Source for Production of Ions of Deuterium Extracted from a Rf plasma) is an ion source test bed designed to extract and accelerate a negative ion current up to 40 A and 100 kV whose first beam is expected by the end of 2016. Two main effects perturb beamlet optics during the acceleration stage: space charge repulsion and the deflection ind...
Article
A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed...
Article
The MITICA experiment (Megavolt ITER Injector & Concept Advancement) is the prototype and the test bed of the Heating and Current Drive Neutral Beam Injectors, which will be necessary for the full-performance exploitation of ITER. MITICA injector experiments shall demonstrate the reliable and accurate emission of a 17 MW beam of neutral particles f...
Article
The ITER Neutral Beam Test Facility (PRIMA) is presently under construction at Consorzio RFX (Padova, Italy). PRIMA includes two experimental devices: an ITER-size ion source with low voltage extraction, called SPIDER, and the full prototype of the whole ITER Heating Neutral Beams (HNBs), called MITICA.The purpose of MITICA is to demonstrate that a...
Article
The RFX-mod device is operated both as a reversed field pinch (RFP), where advanced regimes featuring helical shape develop, and as a tokamak. Due to its flexibility, RFX-mod is contributing to the solution of key issues in the roadmap to ITER and DEMO, including MHD instability control, internal transport barriers, edge transport and turbulence, i...
Article
The physics design of the accelerator for the heating neutral beamline on ITER is now fnished and this paper describes the considerations and choices which constitute the basis of this design. Equal acceleration gaps of 88mm have been chosen to improve the voltage holding capability while keeping the beam divergence low. Kerbs (metallic plates arou...
Article
Full-text available
The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1 MV a 40 A beam of negative deuterium ions, to deliver to the plasma a power of about 17 MW for one hour. As these requirements have never been experimentally met, it was recognized as necessary to setup a test facility, PRIMA (Padova Research on ITER...
Article
This paper describes the R&D work performed in support of the design of the alumina insulators for the MITICA Neutral Beam Injector. The ceramic insulators are critical elements, both from the structural and electrical point of view, of the 1 MV electrostatic accelerator of the MITICA injector, as they are required to sustain both the mechanical lo...
Article
MITICA is a prototype of the heating neutral beam (HNB) Injectors for ITER, built with the purpose of validating the injector design and optimizing its operation. Its goal is to produce a focused beam of neutral particles (H or D) with energy up to 1 MeV and power of 16 MW for 1 h. MITICA includes a Radio Frequency (RF) Plasma Source for the produc...
Conference Paper
The design of the magnetic field configuration in the SPIDER and MITICA negative ion beam sources has evolved considerably during the past four years. This evolution was driven by three factors: 1) the experimental results of the large RF-driven ion sources at IPP, which have provided valuable indications on the optimal magnetic configurations for...
Conference Paper
Neutral beam injection is the main method for plasma heating in magnetic confinement fusion devices. In high energy injector (E>100 keV/amu), neutrals are obtained with reasonable efficiency by conversion of negative ions (H- or D-) via electron detachment reactions. In the case of ITER injectors, which shall operate at 1 MeV, a total ion current...
Conference Paper
Full-text available
The ITER project requires additional heating provided by two injectors of neutral beams resulting from the neutralisation of accelerated negative ions. To study and optimise negative ion production, the SPIDER test facility (particle energy 100keV; beam current 50A) is under construction in Padova, with the aim of testing beam characteristics and...
Article
MITICA is the complete full-scale prototype of a 17 MW heating neutral beam injector for ITER. This experimental device, presently under construction in Padova, includes a negative ion source (H- or D-), and an electrostatic accelerator (1 MV, 40 A, 3600 s). Voltage holding is recognized to be one of the most critical issues for the 1 MV accelerato...
Article
Neutral beam injectors are the main source of plasma heating in advanced fusion devices. To support the realization and optimize the performances of the injectors of ITER tokamak, a dedicated test bed is under construction at Consorzio RFX, Padova. This facility will include a full scale prototype of the injector, named megavolt ITER injector conce...
Article
A comprehensive set of research and development activities has been carried out at Consorzio RFX regarding the construction of the grids for the ITER neutral beam injectors, in order to validate the proposed manufacturing methodologies, to further develop the details of the engineering design, and to adapt existing production techniques to the spec...
Article
The injection of high energy beams of neutral particles is a fundamental method for plasma heating to ignition in the advanced fusion devices. The requirements of the heating neutral beam to be installed on ITER Tokamak and of the full scale prototype megavolt ITER injector and concept advancement represent a large extrapolation from existing devic...
Article
The Source for Production of Ion of Deuterium Extracted from Rf plasma (SPIDER) test facility is under construction in Padova to optimise the operation of the beam source of ITER neutral beam injectors. The SPIDER beam will be characterised by the instrumented calorimeter STRIKE, whose main components are one-directional carbon-fibre-carbon-composi...
Article
Two Neutral Beam Injectors (NBI) are foreseen to provide a substantial fraction of the heating power necessary to ignite thermonuclear fusion reactions in ITER. The development of the NBI system at unprecedented parameters (40 A of negative ion current accelerated up to 1 MV) requires the realization of a full scale prototype, to be tested and opti...
Article
A new magnetic configuration is proposed for the suppression of co-extracted electrons in a negative-ion accelerator. This configuration is produced by an arrangement of permanent magnets embedded in one accelerator grid and creates an asymmetric local magnetic field on the upstream and downstream sides of this grid. Thanks to the "concentration" o...
Article
MITICA (Megavolt ITER Injector Concept Advancement) is a test facility for the development of a full-size heating and current drive neutral beam injectors for the ITER Tokamak reactor. The optimized electrostatic and magnetic configuration has been defined by means of an iterative optimization involving all the physics and the engineering aspects....
Article
This paper summarizes the progress of R&D activities related to the design of in-vessel magnetic sensors for measurement of the equilibrium field in ITER and the associated mechanical support and connection system. The background to the design activities, developed in the last few years in the framework of several collaborations, is provided in the...
Conference Paper
The injection of high energy beams of neutral particles is a fundamental method for plasma heating to ignition in the advanced fusion devices. In order to realize the neutral beam injectors (NBIs) operating on the ITER tokamak the construction of a dedicated test facility is in progress at Consorzio RFX, Padova. This facility will host a full scale...
Conference Paper
MITICA is the complete full-scale prototype of a 17 MW Heating Neutral Beam Injector for ITER. This experimental device, presently under construction in Padova, includes a negative Ion Source (H- or D-), and an electrostatic Accelerator (1 MV, 40 A, 3600 s). Voltage holding is recognized to be one of the most critical issues for the 1 MV accelerato...
Conference Paper
A comprehensive set of R&D activities has been carried out at Consorzio RFX regarding the construction of the grids for the ITER Neutral Beam Injectors, in order to validate the proposed manufacturing methodologies, to further develop the details of the engineering design, and to adapt existing production techniques to the specific case. In the fra...
Conference Paper
MITICA is a prototype of the Heating Neutral Beam (HNB) Injectors for ITER [1]. The MITICA scientific objective is to validate the design and optimize the operating performances of the injector before installation on ITER. The magnetic field configuration in the injector is critical for obtaining the required efficiency and beam optics. In order to...
Conference Paper
The MITICA experiment will be the full scale prototype of the neutral beam injectors to be installed on the ITER device. Its aim is to demonstrate and optimise a 16 MW neutral beam power, obtained by neutralization of a 56 A deuterium negative ion beam D- accelerated to an energy of 1 MeV. Since the current expected density available at the source...
Conference Paper
Full-text available
An experimental Cold Crucible Levitation Melting system has been designed, built and commissioned at the Dept. of Management and Engineering (DTG) of the University of Padova in Vicenza. The system is able to process few hundreds of grams of light metal alloy in air, in medium or high vacuum conditions or in inert gas atmosphere, and it has been de...
Conference Paper
Full-text available
The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1MV a 40A beam of negative deuterons, delivering to the plasma about 17MW up to one hour. As these requirements have never been experimentally met, it was decided to build a test facility, PRIMA (Padova Research on ITER Megavolt Accelerator), in Italy,...