SPIDER (Source for the Production of Ions
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...
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...
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...
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...
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...
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.
At the end of 2021, a scheduled long-term shutdown started to perform major...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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,...
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...
