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Riccardo Agnello

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Publications associées (46)

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Helicon wave plasma generated by a resonant birdcage antenna: magnetic field measurements and analysis in the RAID linear device

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, Rémy Jacquier, Riccardo Agnello

This paper describes a helicon-wave-sustained plasma generated by a novel birdcage antenna with cosine azimuthal current distribution. The resonant birdcage source maintains a stable intense plasma column from low (300 W) to high (10 kW) steady-state RF po ...

2021

A 1.5D fluid-Monte Carlo model of a hydrogen helicon plasma

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, Rémy Jacquier, Riccardo Agnello

Helicon plasma sources operating with hydrogen or deuterium might be attractive for fusion applications due to their higher power efficiency compared to inductive radiofrequency plasma sources. In recent years, the resonant antenna ion device (RAID) has be ...

2022

Magnetic field configurational study on a helicon-based plasma source for future neutral beam systems

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, Rémy Jacquier, Riccardo Agnello

A helicon-based plasma source is under development and exploration at CEA-IRFM to produce an efficient and dense magnetized plasma column. The final objective of this development is the extraction and acceleration of a blade-like negative ion beam in view ...

IOP PUBLISHING LTD2019

Negative Hydrogen Ions in a Helicon Plasma Source

Riccardo Agnello

There is nowadays a large interest to employ helicon plasmas as sources of negative ions for Neutral Beam Injectors (NBIs). Helicon plasma sources offer a number of advantages compared to current Inductive Couple Plasma (ICP) negative ions source, such as ...

EPFL2020

Ion heating and flows in a high power helicon source

Alan Howling, Ivo Furno, Gennady Plyushchev, Rémy Jacquier, Riccardo Agnello

We report experimental measurements of ion temperatures and flows in a high power, linear, magnetized, helicon plasma device, the Resonant Antenna Ion Device (RAID). Parallel and perpendicular ion temperatures on the order of 0.6 eV are observed for an rf ...

Amer Inst Physics2017

The AWAKE Run 2 Programme and Beyond

Patrick Blanchard, Ambrogio Fasoli, Ivo Furno, Yanis Andrebe, Riccardo Agnello, Christine Stollberg

Plasma wakefield acceleration is a promising technology to reduce the size of particle accelerators. The use of high energy protons to drive wakefields in plasma has been demonstrated during Run 1 of the AWAKE programme at CERN. Protons of energy 400 GeV d ...

2022

Cavity ring-down spectroscopy to measure negative ion density in a helicon plasma source for fusion neutral beams

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, Yanis Andrebe, Gennady Plyushchev, Rémy Jacquier, Riccardo Agnello

Cavity Ring Down Spectroscopy (CRDS) is used to measure the D- absolute density produced in the helicon plasma reactor RAID (Resonant Antenna Ion Device) at the Swiss Plasma Center. The birdcage geometry of the helicon antenna produces a homogeneous, high- ...

2018

Filamentation of a relativistic proton bunch in plasma

Patrick Blanchard, Ambrogio Fasoli, Ivo Furno, Yanis Andrebe, Riccardo Agnello, Christine Stollberg

We show in experiments that a long, underdense, relativistic proton bunch propagating in plasma undergoes the oblique instability, which we observe as filamentation. We determine a threshold value for the ratio between the bunch transverse size and plasma ...

2024

Helicon wave-generated plasmas for negative ion beams for fusion

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, Gennady Plyushchev, Rémy Jacquier, Claudio Marini, Riccardo Agnello

In the next generation of fusion reactors, such as DEMO, neutral beam injectors (NBIs) of high energy (0.8-1 MeV) deuterium atom swith high wall-plug efficiency (>50%) will be required to reach burning plasma conditions and to provide a significant amount ...

2017

Study of Negative Ion Beamlets Produced in SPIDER by Beam Emission Spectroscopy

Riccardo Agnello

Among the beam diagnostics routinely employed in source for production of ion of deuterium (SPIDER), beam emission spectroscopy (BES) provides valuable information for beam characterization, thus driving source optimization methods. In particular, this tec ...

2022

First operations with caesium of the negative ion source SPIDER

Basile Marie Jacques Pouradier Duteil, Riccardo Agnello

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 the optimization of the full-scale plasma source in the SPIDER test stand. The production of H- or D- ions ...

IOP Publishing Ltd2022

Controlled Growth of the Self-Modulation of a Relativistic Proton Bunch in Plasma

Patrick Blanchard, Ambrogio Fasoli, Ivo Furno, Yanis Andrebe, Riccardo Agnello, Christine Stollberg

A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self -modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility ...

2022

First B-dot measurements in the RAID device, an alternative negative ion source for DEMO neutral beams

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, Gennady Plyushchev, Rémy Jacquier, Claudio Marini, Basile Marie Jacques Pouradier Duteil, Riccardo Agnello

As a new concept of Neutral Beam Injectors (NBI) for DEMO-like reactors, SIPHORE (IRFM, CEA, in France) expects to extract negative deuterium ions and photo-neutralize the accelerated D-. The Swiss Plasma Center (SPC) of EPFL is involved in this project by ...

Elsevier B.V.2019

Thomson scattering measurements in the divertor region of the TCV Tokamak plasmas

Patrick Blanchard, Basil Duval, Pierre-François Isoz, Pierre Lavanchy, Xavier Llobet, Blaise Marlétaz, Ivo Furno, Yanis Andrebe, Severino Antonioni, Jonathan Sylvain Masur, Steve Couturier, Joan Decker, Riccardo Agnello, Hugo Antoine Georges Arnichand

In order to better study conventional and alternative divertor configurations, the TCV Tokamak was recently upgraded. In-vessel graphite baffles were installed in the TCV chamber to delimit a separate divertor chamber from the core that required enhanced d ...

2019

Lessons learned after three years of SPIDER operation and the first MITICA integrated tests

Basile Marie Jacques Pouradier Duteil, Riccardo Agnello

ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system, to reach the desired performances during its various phases of operation. The 16.5 MW expected neutral beam power p ...

2023

Experimental study of wakefields driven by a self-modulating proton bunch in plasma

Patrick Blanchard, Ambrogio Fasoli, Alan Howling, Ivo Furno, Yanis Andrebe, Sun Hee Kim, Rémy Jacquier, Ishkhan Gorgisyan, Riccardo Agnello, Yiming Li

We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. We show that the wakefields' growth and amplitude increase with increasing seed amplitude as well as with the ...

2020

Experimental Observation of the Motion of Ions in a Resonantly Driven Plasma Wakefield Accelerator

Patrick Blanchard, Ambrogio Fasoli, Ivo Furno, Yanis Andrebe, Riccardo Agnello, Christine Stollberg

We show experimentally that an effect of motion of ions, observed in a plasma-based accelerator, depends inversely on the plasma ion mass. The effect appears within a single wakefield event and manifests itself as a bunch tail, occurring only when sufficie ...

2025

Hosing of a Long Relativistic Particle Bunch in Plasma

Patrick Blanchard, Ambrogio Fasoli, Ivo Furno, Yanis Andrebe, Alban Sublet, Sun Hee Kim, Riccardo Agnello, Christine Stollberg

Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, selfmodulation in the perpendicular plane, at frequencies clo ...

Amer Physical Soc2024

Characterization of Cs-free negative ion production in the ion source SPIDER by cavity ring-down spectroscopy

Riccardo Agnello

The neutral beam injectors of the ITER experiment will be based on negative ion sources for the generation of beams composed by 1MeV H/D particles. The prototype of these sources is currently under testing in the SPIDER experiment, part of the Neutral Beam ...

2022

Technology challenges and integration of the plasma position reflectometer in RFX-mod2

Riccardo Agnello

The integration of the new plasma position reflectometer in the RFX-mod2 experiment (the upgraded version of the previous RFX-mod that operated until 2015) is presented in this contribution. Particular attention has been devoted to the high field side subs ...

Elsevier Science Sa2024