A5079811904- Particle accelerators and beam dynamics
- Magnetic confinement fusion research
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Gyrotron and Vacuum Electronics Research
- Fusion materials and technologies
- Laser-induced spectroscopy and plasma
- Dust and Plasma Wave Phenomena
- Atomic and Subatomic Physics Research
- Ion-surface interactions and analysis
- Muon and positron interactions and applications
- Plasma Applications and Diagnostics
- Scientific Measurement and Uncertainty Evaluation
- Additive Manufacturing and 3D Printing Technologies
- Electrohydrodynamics and Fluid Dynamics
- Mass Spectrometry Techniques and Applications
- Aquatic and Environmental Studies
- Diamond and Carbon-based Materials Research
- Additive Manufacturing Materials and Processes
- Anodic Oxide Films and Nanostructures
- Corrosion Behavior and Inhibition
- Spacecraft and Cryogenic Technologies
- Fusion and Plasma Physics Studies
Sorbonne Université
2024
CEA Cadarache
2023-2024
Centre National de la Recherche Scientifique
2007-2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2023-2024
Laboratoire de Physique des Plasmas
2024
École Polytechnique
2024
Laboratoire de Physique des Gaz et des Plasmas
2021-2023
Université Paris-Saclay
2023
Max Planck Institute for Plasma Physics
2011-2021
Max Planck Society
2011-2019
The ITER neutral beam system will be equipped with radio-frequency (RF) negative ion sources, based on the IPP Garching prototype source design. Up to 100 kW at 1 MHz is coupled RF driver, out of which plasma expands into main chamber. Compared arc driven sources are maintenance free and without evaporation tungsten. modularity driver concept permits supply large volumes. (one driver) demonstrated operation in hydrogen deuterium up one hour relevant parameters. ELISE test facility operating...
Axially resolved measurements of plasma parameters were performed by two Langmuir probes moving in parallel from the exit driver (where is generated) up to extraction region neighbourhood IPP RF negative hydrogen ion source prototype. At exit, show an unexpected inhomogeneity presence magnetic field: a cold and dense flows out top part while hot low density bottom part. A local relation between derived conservation energy flux.
The ITER neutral beam system requires a negative hydrogen ion of 48 A with an energy 0.87 MeV and deuterium 40 1 MeV. is extracted from large RF driven source the dimension 1.9 × 0.9 m 2 . An important role for transport ions to extractor suppression co-extracted electrons magnetic filter field in front extractor. For will be generated by current up 4 kA flowing through first grid extrapolation results obtained small IPP prototype source, where has different 3D structure as it permanent...
High power negative hydrogen ion sources operating at 0.3 Pa are a key component of the neutral beam injection systems for international fusion experiment ITER. To achieve required large current tolerable number co-extracted electrons source is equipped with magnetic filter field (up to 10 mT). The IPP prototype (1/8 area ITER source) has been flexible frame perform studies (position, polarity, strength). Axial profiles plasma parameters measured two Langmuir probes, positioned in upper and...
SPIDER is one of the two projects ITER Neutral Beam Test Facility (NBTF) under construction in Padova, Italy, at Consorzio RFX premises; it will have a 100 keV beam source with full-size prototype radiofrequency (RF) ion for Injector (NBI), designed to operate pulse length up 3600 s, featuring ITER-like filter field configuration, caesium oven layout and wide set diagnostics.These features allow reproducing operation like as cannot be done any other existing test facility.SPIDER realization...
The test facility ELISE represents an important step in the European R&D roadmap towards neutral beam injection (NBI) systems on ITER. provides early experience with operation of large radio frequency (RF) driven negative hydrogen ion sources. Starting first plasma pulses March 2013, has demonstrated stable 1 h discharges repetitive 10 s extraction every 3 min and deuterium at pressure 0.3 Pa required by Stable currents 9.3 A 5.8 have been extracted using only one quarter available RF power...
Systematic Langmuir probe measurements were performed during the caesium (Cs) conditioning of IPP prototype negative hydrogen ion source. Conditioning consists slowly injecting into source in order to increase extracted current and minimize co-extracted electrons. This process usually takes several days. Measurements taken near plasma grid (PG) where majority ions are created. A clear transition between a poorly conditioned (volume dominated H− production) well (surface was seen. By...
A 2D self-consistent fluid plasma model is employed for studying the in radio-frequency (RF)-driven negative hydrogen ion source prototype developed to equip neutral beam injector systems ITER. The considered its usual configuration with a cylindrical driver and magnetic filter field (MF) produced by permanent magnets arranged magnet frame movable along expansion chamber. accounts RF injection, bias potential applied at grid (PG) losses of particles electron energy third dimension, i.e....
The transport of protons in a RF-driven negative hydrogen ion source for ITER NBI was investigated by means 3D Monte Carlo code. As input the code consistent axial profile electrostatic potential complete constructed. difference between plasma generation volume and grid is range 10–20 V depends on RF power, filling pressure bias voltage. mean free path proton collisions with background gas several centimeters which that are noticeably decelerated scattered. velocity distribution function...
We measure H− negative ions by means of a mass spectrometer in helicon plasma reactor. The H2 operates at low injected RF power (50–300 W), capacitive regime, under pressure conditions (between 0.4 and 1 Pa). A highly oriented pyrolytic graphite (HOPG) sample centred the expanding chamber facing nozzle placed 40 mm away is negatively biased. Negative formed on surface upon positive ion bombardment are detected according to their energy spectrometer. obtain distribution function (IDF) showing...
A graphite sample is negatively biased in a hydrogen plasma. H− ions created on the surface are accelerated by sheath toward mass spectrometer where they detected according to their energy. The ion distribution function shows two contributions: main peak followed an energetic tail. It was previously proven backscattering of positive as negative responsible for high energy In this paper we demonstrate 75% production coming from sputtering adsorbed atoms ions. threshold mechanism around 20 eV...
In previous works, surface-produced negative-ion distribution-functions have been measured in H2 and D2 plasmas using graphite surfaces (highly oriented pyrolitic graphite). the present paper, we use srim software to interpret distribution-functions. For this purpose, of backscattered sputtered atoms arising due impact hydrogen ions on a-CH a-CD are calculated. The calculations confirm experimental deduction that backscattering sputtering mechanisms origin creation negative at surface. It is...
Negative hydrogen ion sources for fusion are based on the surface conversion process and operate with both cesium seeded deuterium plasmas. Although required extracted negative densities achieved, source performance is limited at present by amount of co-extracted electrons, which much higher in than up to now unknown reasons. Systematic Langmuir probe measurements combined emission spectroscopy have been carried out ITER prototype source. They show very similar electron temperatures plasma...
Continuing our previous studies concerning H− negative ion generation mechanisms on graphite surfaces in hydrogen plasma, we studied D− surface deuterium plasma. We measured the produced distribution functions (IDF) and compared them with ones. formation are identical to The backscattering of an incident positive as a accounts for IDF high energy part, while sputtering adsorbed atom mechanism two superimposed explaining main peak. maximum is always lower than that H−. This isotopic effect...
A study was conducted on the large 1/2-size ITER source RADI testbed in order to determine influence of magnetic field strength plasma parameters neighbourhood grid.The at is created by a current flowing grid; contrast small IPP prototype where permanent magnets are used.The investigations show homogeneity within 10 % near grid along direction lines as well reduction electron temperature.In perpendicular lines, and for strengths higher than 2.4 mT, density shows minimum due reduced transport...
BATMAN (Bavarian Test Machine for Negative ions) is a test facility equipped with 18 scale H− source the ITER heating neutral beam injection. Several diagnostics in boundary layer close to plasma grid (first of accelerator system) followed transition from volume surface dominated production starting Cs-free, cleaned and subsequent evaporation caesium, while has been operated at relevant pressure 0.3 Pa: Langmuir probes are used determine potential, optical emission spectroscopy follow...
It has been observed that there are differences between the uncompensated Langmuir probes installed in upper and lower areas of rf driven H− sources at IPP Garching. The two often had substantially different floating potentials or ion saturation currents. In an effort to understand reasons for these a probe analysis system was used on collect full current voltage characteristic. results show what is likely formation ion-ion plasma. paper shows effect beam extraction presence caesium characteristics.
The Source for Production of Ion Deuterium Extracted from Rf plasma (SPIDER) test facility is under construction in Padova to optimise the operation beam source ITER neutral injectors. SPIDER will be characterised by instrumented calorimeter STRIKE, whose main components are one-directional carbon-fibre-carbon-composite tiles. A small-scale version entire system has been employed BAvarian Test MAchine Negative ions (BATMAN) testbed arranging two prototype tiles vertical direction. paper...
A numerical model, based on the fluid plasma theory, has been used for description of spatial distribution parameters (electron density and temperature, potential as well densities three types positive hydrogen ions) in IPP prototype RF negative ion source. The model covers driver expansion region source with their actual size accounts presence magnetic filter field its value location bias applied to grid. obtained results show that without a two 2D geometries considered, respectively, an...
Neutral beam injection (NBI) systems are required for heating and current drive in the next generation fusion experiment ITER, strict requirements placed on beamlet core divergence (<7 mrad) transmission into tokamak. The measurement of single is challenging due to multi-beamlet nature negative ion sources that such systems; diagnostic compatible with large high power beams can only provide spatially averaged measurements, leading mixing signals within results. To improve...
Future magnetic-confinement nuclear fusion experiments will be using neutral beam injection (NBI) systems for plasma heating that are based on sources negative hydrogen ions as opposed to the positive mostly used date. An unavoidable effect in NBI (NNBI) is creation of acceleration region due collisions between fast and background gas. These accelerated back into ion source. At high extracted current densities from NNBI voltages—1 MeV case ITER—the resulting heat load backplate source...