V. Candeloro
A5007959932- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Fusion materials and technologies
- Superconducting Materials and Applications
- Plasma Applications and Diagnostics
- Magnetic Properties and Applications
- Electric Motor Design and Analysis
- Induction Heating and Inverter Technology
- Ionosphere and magnetosphere dynamics
- Particle Accelerators and Free-Electron Lasers
University of Padua
2019-2024
National Agency for New Technologies, Energy and Sustainable Economic Development
2022-2024
Centro Ricerche FIAT
2023
Abstract The negative-ion based neutral beam injector for heating and current drive of the ITER plasma (ITER HNB) is under development, at present focusing on optimization full-scale source in SPIDER test stand. production H − or D ions ion low work function surfaces obtained by caesium evaporation. This paper describes conditioning procedure corresponding performances during first operation with caesium. Technical solutions to overcome limitations stand are described. influence parameters...
Giant negative ion sources for neutral beam injectors deliver huge currents, thanks to their multi-beamlet configuration. As the single-beamlet optics defines transmission losses along beamline, extraction of a similar current all beamlets is extremely desirable, in order facilitate source operation (i.e., around perveance match). This Review investigates correlation between vertical profile intensity and profiles plasma properties at region source, focusing on influence increasing cesium...
An overview of the recent operations and main results cesium injection in Source for Production Ions Deuterium Extracted from Rf plasma (SPIDER) negative ion source are described this contribution. In experiments without injection, all SPIDER plants were tested to verify basic expectations on operational parameters (e.g., electron cooling effectiveness magnetic filter field) determine its region. For beam properties, it was shown that current density varies across vertical direction....
The neutral beam test facility (NBTF), built in Consorzio RFX (Padua, Italy), aims at optimizing the ITER injectors through dedicated devices. hosts full-size prototype of ion source injectors, for production ions deuterium extracted from a radiofrequency plasma (SPIDER), radio frequency-based, cesium-assisted negative source. is by triode with total acceleration voltage up to 108 kV; each grid provided 1280 apertures. On side, electrode [plasma (PG)] partially covered an additional [bias...
SPIDER is the full-scale prototype of plasma source negative-ion driven neutral beam injector for heating and current drive ITER plasma. The uniqueness complexity system requested this ad hoc test stand aiming at optimizing performance RF inductively generated plasma, negative ion production extraction, electron filtering, robustness controllability all systems required to work together. After about three years operation, presently in a long shutdown, which whole accelerator were dismounted....
Abstract Cusp-shaped magnetic fields are widely used to confine plasmas in various applications. This field configuration allows localise plasma losses: the width of such loss cone, usually called leak width, was found be proportional geometric mean ion and electron Larmor radii, so that it becomes smaller for increasing intensity. At same time, diffusion towards walls is reduced regions where lines parallel surfaces, leading formation a Plasma Exclusion Zone (PEZ) whose characteristic...
This contribution describes the commissioning and first operation of a fixed triple Langmuir probe in source for production ions deuterium extracted from radio frequency plasma (SPIDER), full-scale prototype negative-ion ITER neutral beam injectors. diagnostic is capable measuring time evolution main features entire duration discharge, allowing to correlate local properties, such as density, electron temperature, potential, control parameters, i.e., filter field intensity, (RF) power, bias...
Abstract Three years of experiments on SPIDER allowed characterization the main features source plasma and negative ion beam, in original design configuration. For large dimensions chamber, extraction area, investigation single-beamlet currents uniformity had to be carried out extend knowledge gained smaller prototype sources. The configuration multiple RF drivers filter field topologies were found cause a peculiar behavior confinement drivers, creating left-right asymmetries which also...
SPIDER is the 100 keV full-size Negative Ion Source prototype of ITER Neutral Beam Injector, operating at Consorzio RFX in Padova, Italy. The largest world, generates an RF driven plasma from which Deuterium or Hydrogen negative ions are produced and extracted. At end 2021, a scheduled long-term shutdown started to introduce major modifications improvements aiming solve issues drawbacks identified during first three years operations. action period was disassembly characterization beam source...
SPIDER is the prototype ion source of MITICA, full-size neutral beam heating system conceived for ITER tokamak. It includes eight drivers to heat and sustain inductively coupled plasma (ICP). Owing their near cylindrical symmetry, coupling between radio-frequency (RF) active currents studied using a 2D electromagnetic approach with simplified expressions electrical conductivity taken from literature. The power absorbed by effect induced in lowering inductance driver are based on data...
Stable and uniform beams with low divergence are required in particle accelerators; therefore, beyond the accelerated current, measuring beam current spatial uniformity stability over time is necessary to assess performance, since these parameters affect perveance thus optics. For high-power operating long pulses, it convenient directly measure a non-intercepting system due heat management requirement. Such needs be capable of vacuum presence strong electromagnetic fields overvoltages,...
Movable electrical probes were used to diagnose the beam flux profile and potential of ion beams since early 1960s. Experimental measurements plasmas can provide essential data related space charge neutralization, but current–voltage characteristics obtained from such are dominated by impact ion-induced secondary emission. In this work, we present an analysis Langmuir in a negative beam. We identify discuss separately contributions collected current given plasma ions electrons, stripped...
Abstract The experimental fusion reactor ITER will feature two (or three) heating neutral beam injectors (NBI) capable of delivering 33(or 50) MW power into the plasma. A NBI consists a plasma source for production negative ions (extracted ion current up to 329 A/m 2 in H and 285 D) then accelerated 1 MeV one hour. is neutralized, residual are electrostatically removed before injection. beamline was designed divergence between 3 7 mrad. NBIs relies on RF-driven, Inductively-Coupled Plasmas...
Abstract SPIDER, an RF-driven negative ion source in the Neutral Beam Test Facility (NBTF), serves as prototype for ITER's neutral beam injector (NBI). It is composed of 8 drivers powered by 4 RF generators, aiming to accelerate 50 A hydrogen ions 100 KeV with a uniformity target 10%. The experiment, launched 2018, tested production using caesium. Results match those similar facilities, but SPIDER faces challenges due its size, multiple drivers, and non-uniform plasma expansion. These issues...
Abstract Most of the currently operating Negative ion Neutral Beam Injectors (N-NBIs) exploit filament powered sources for generation beam ions. Being widely used in fusion experiments, arc technology has been thoroughly investigated and optimized over years, allowing to achieve excellent performances terms extracted optics. The source geometry, magnetic field topology power strongly influence both plasma discharge background gas properties and, consequently, features. In this framework,...
This contribution describes the design of a movable Langmuir probe system to be permanently installed in SPIDER negative ion source. diagnostic aims at measuring axial profiles plasma density, electron temperature and floating potential both driver expansion region, with view further investigate positive dynamics. Furthermore, deeper understanding formation mechanism RF coupling can provided, e,g. via estimation Electron Energy Distribution Function (EEDF) inside driver. Thermal analyses...
SPIDER is the prototype ion source of MITICA, full-size neutral beam heating system conceived for ITER tokamak. It includes eight drivers to heat and sustain inductively coupled plasma (ICP). Owing their near cylindrical symmetry, coupling between radio-frequency (RF) active currents studied using a 2D electromagnetic approach with simplified expressions electrical conductivity taken from literature. The power absorbed by effect induced in lowering inductance driver are based on data...
Abstract The ITER fusion reactor will be heated by fast neutral beams generated accelerating and neutralizing negative ions, produced in a RF inductively-coupled plasma which expands through region featuring magnetic filter. During the current shut down of SPIDER device (until 2023) some modifications have been planned to improve system performance. These are based on experience gained during operation previous years include, among others, addition further sets permanent magnets expansion...