Publications by Riccardo Agnello

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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 ...

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 ...

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 ...

Three years of experiments on SPIDER allowed characterization of the main features of the source plasma and of the negative ion beam, in the original design configuration. For the large dimensions of the source chamber, and of the extraction area, the inve ...

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 ...

The primary goals of the STRong lensing Insights into the Dark Energy Survey (STRIDES) collaboration are to measure the dark energy equation of state parameter and the free streaming length of dark matter. To this aim, STRIDES is discovering strongly lense ...

The Heating Neutral Beam Injectors (HNBs) for ITER will have to deliver 16.7 MW beams of H/D particles at 1 MeV energy. The beams will be produced from H -/D- ions, generated by a radiofrequency plasma source coupled to an ion acceleration system. A protot ...

The negative ion source SPIDER at Consorzio RFX (Italy) is a crucial experimental step towards the development of the Heating Neutral Beam (HNB) injectors for ITER. The goal of SPIDER is to operate and optimize a full-scale negative ion source in hydrogen ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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- ...

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 ...

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 ...

Riccardo Agnello

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

A double-ended helicon source to symmetrize RAID plasma

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

Highlights of recent SPIDER results and improvements

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

The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign - I. Overview and classification of candidates selected by two techniques

Characterization of cesium and H-/D- density in the negative ion source SPIDER

Measurement of stripping losses in the negative ion source SPIDER

Application of Thomson scattering to helicon plasma sources

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

Vibrational excitation and dissociation of deuterium molecule by electron impact

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

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

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

Continuous pulse advances in the negative ion source NIO1

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

The AWAKE Run 2 Programme and Beyond

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

Filamentation of a relativistic proton bunch in plasma

Helicon wave-generated plasmas for negative ion beams for fusion