Publications by Riccardo Agnello

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

Ambrogio Fasoli, Ivo Furno, Patrick Blanchard, 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

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

Optical emission spectroscopy and microwave reflectometry for magnetised plasmas: Applications to ion sources and fusion machines

Riccardo Agnello

. - Investigation of magnetised plasmas by advanced diagnostics is a relevant topic in the frame of ion sources for high-performance particle accelerators and in thermonuclear fusion research for energetic purposes. In this paper, we propose two different ...

SOC ITALIANA FISICA2024

Hosing of a Long Relativistic Particle Bunch in Plasma

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

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

Optimizing the ITER NBI ion source by dedicated RF driver test stand

Riccardo Agnello

The experimental fusion reactor ITER will feature two (or three) heating neutral beam injectors (NBI) capable of delivering 33(or 50) MW of power into the plasma. A NBI consists of a plasma source for production of negative ions (extracted negative ion cur ...

Institute of Physics2024

Filamentation of a relativistic proton bunch in plasma

Ambrogio Fasoli, Ivo Furno, Patrick Blanchard, 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

Numerical and experimental investigations of a microwave interferometer for the negative ion source SPIDER

Ivo Furno, Rémy Jacquier, Riccardo Agnello

The electron density close to the extraction grids and the co-extracted electrons represent a crucial issue when operating negative ion sources for fusion reactors. An excessive electron density in the plasma expansion region can indeed inhibit the negativ ...

IOP Publishing Ltd2023

Continuous pulse advances in the negative ion source NIO1

Riccardo Agnello

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 ke ...

2023

Development of the self-modulation instability of a relativistic proton bunch in plasma

Ambrogio Fasoli, Ivo Furno, Patrick Blanchard, Yanis Andrebe, Riccardo Agnello, Christine Stollberg, Sun Hee Kim, Ana Francisca Leal Silva Soares, Alban Sublet, Samuel Rey-Mermet

Self-modulation is a beam-plasma instability that is useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size ...

2023

A double-ended helicon source to symmetrize RAID plasma

Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne, Rémy Jacquier, Marcelo Baquero Ruiz, Riccardo Agnello, Christine Stollberg

Neutral Beam Injectors (NBI) for post-DEMO-like reactors must achieve a neutralization efficiency (fraction neutrals/ions) above 70%. To reach this, NBIs based on negative ions are necessary and an innovative concept of this type of injector is based on ph ...

2023