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Riccardo Agnello

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Related publications (46)

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

Negative hydrogen ion dynamics inside the plasma volume of a linear device: Estimates from particle-in-cell calculations

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

Negative hydrogen or deuterium ions are the precursor particles used to generate a high power beam of neutrals in order to heat the tokamak plasma core of magnetic fusion devices, inject current, and to some extent control instabilities. In the case of ITE ...

2021

Laser photo-detachment combined with Langmuir probe in magnetized electronegative plasma: how the probe size affects the plasma dynamic?

Ivo Furno, Riccardo Agnello

Laser photo-detachment combined with a Langmuir probe (LP) is used to diagnose negative ion properties in electronegative plasmas. The technique relies on the combined use of a laser pulse and an LP. The laser pulse converts negative ions into electron-ato ...

2021

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

Experimental study of extended timescale dynamics of a plasma wakefield driven by a self-modulated proton bunch

Patrick Blanchard, Ambrogio Fasoli, Alan Howling, Ivo Furno, Yanis Andrebe, Rémy Jacquier, Riccardo Agnello

Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bun ...

2021

Latest experimental and theoretical advances in the production of negative ions in caesium-free plasmas

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

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 thes ...

2021

Simulation and experimental study of proton bunch self-modulation in plasma with linear density gradients

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

We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechae ...

2021

Vibrational excitation and dissociation of deuterium molecule by electron impact

Ivo Furno, Riccardo Agnello

A theoretical investigation of electron-D-2 resonant collisions-via the low-lying and the Rydberg states of D-2(-)-is presented for vibrational excitation, dissociative electron attachment and dissociative excitation processes by using the local-complex-po ...

2021

On the road to ITER NBIs: SPIDER improvement after first operation and MITICA construction progress

Elena Gaio, Riccardo Agnello, Michele Fadone, Alberto Ferro

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 ...

2021

Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma

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

We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufticient initial amplitude [>= (4.1 +/- 0.4) MV/m], the phase of ...

2021

Development and first operation of a cavity ring down spectroscopy diagnostic in the negative ion source SPIDER

Riccardo Agnello

The neutral beam injectors of the ITER experiment will rely on negative ion sources to produce 16.7 MW beams of H/D particles accelerated at 1 MeV. The prototype of these sources was built and is currently operated in the SPIDER (Source for the Production ...

2021

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, Shuai Liu

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

Negative ion characterization in a helicon plasma source for fusion neutral beams by cavity ring-down spectroscopy and Langmuir probe laser photodetachment

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

Negative ions are characterized in the helicon plasma source resonant antenna ion device (RAID) at the Swiss plasma center by means of cavity ring-down spectroscopy (CRDS) and Langmuir probe (LP)-assisted laser photodetachment. A high density and axially h ...

IOP Publishing Ltd2020

Application of Thomson scattering to helicon plasma sources

Patrick Blanchard, Alan Howling, Ivo Furno, Yanis Andrebe, Alban Sublet, Rémy Jacquier, Riccardo Agnello

The possibility of performing electron density and temperature measurements in a high power helicon plasma is a crucial issue in the framework of the AWAKE (Advanced WAKefield Experiment) project, which demonstrates acceleration of particles using GeV m(-1 ...

Cambridge University Press2020

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

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

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, 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

H0LiCOW-IX. Cosmographic analysis of the doubly imaged quasar SDSS 1206+4332 and a new measurement of the Hubble constant

Georges Meylan, Frédéric Courbin, Vivien François Bonvin, Riccardo Agnello, Hung-Hsu Chan, Adriano Agnello

We present a blind time-delay strong lensing (TDSL) cosmographic analysis of the doubly imaged quasar SDSS 1206+4332. We combine the relative time delay between the quasar images, Hubble Space Telescope imaging, the Keck stellar velocity dispersion of the ...

OXFORD UNIV PRESS2019

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

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

Negative ion characterization in a helicon plasma source for fusion neutral beams by cavity ring-down spectroscopy and Langmuir probe laser photodetachment

Riccardo Agnello

2019

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