Publications by Riccardo Agnello

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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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

. - 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 ...

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 ...

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 ...

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 ...

Riccardo Agnello

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

First operations with caesium of the negative ion source SPIDER

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

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

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

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

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

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

Hosing of a Long Relativistic Particle Bunch in Plasma

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

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

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

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

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

Improvement of SPIDER diagnostic systems

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