Publications de Alan Howling | EPFL Graph Search

Publications associées (68)

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

Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne, 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

Hydrogen-dominated plasma, due to silane depletion, for microcrystalline silicon deposition

Christoph Hollenstein, Alan Howling, Raffaello Sobbia

Plasma conditions for microcrystalline silicon deposition generally require a high flux of atomic hydrogen, relative to SiH alpha=0 -> 3 radicals, on the growing film. The necessary dominant partial pressure of hydrogen in the plasma is conventionally obta ...

American Vacuum Society2010

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

Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne, 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

RNA Sequencing of Arabidopsis thaliana Seedlings after Non-Thermal Plasma-Seed Treatment Reveals Upregulation in Plant Stress and Defense Pathways

Ivo Furno, Alan Howling, Alexandra Waskow

Not all agricultural practices are sustainable; however, non-thermal plasma treatment of seeds may be an eco-friendly alternative to improve macroscopic plant growth parameters. Despite the numerous successful results of plasma-seed treatments reported in ...

2022

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

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

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

A double-ended helicon source to symmetrize RAID plasma

Ivo Furno, Alan Howling, Riccardo Agnello, Marcelo Baquero Ruiz, Philippe Frédérique Bruno Guittienne, Rémy Jacquier, Christine Stollberg, Renat Karimov, Simon Pierre Henri Vincent

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

Two-fluid solutions for Langmuir probes in collisionless and isothermal plasma, over all space and bias potential

Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne

This paper presents solutions for the classical one-dimensional (1D radial and Cartesian) problem of Langmuir probes in a collisionless, isothermal plasma. The method is based on two-fluid equations derived from the first two moments of Vlasov's equation. ...

2018

Application of Thomson scattering to helicon plasma sources

Ivo Furno, Patrick Blanchard, Alan Howling, Yanis Andrebe, Riccardo Agnello, Rémy Jacquier, Hugo Antoine Georges Arnichand, Alban Sublet

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

Slip Ring Test Assembly With Increased Breakdown Voltage Limit for High-Voltage Bus Satellites

Ivo Furno, Alan Howling, Fabio Avino

In this article, a setup including a passive gas breakdown mitigation technique for satellite slip ring assemblies (SRAs) is introduced and tested. The setup features a central conducting ring, separated from two external conducting limiting discs (LDs) by ...

2020

Direct current breakdown in gases for complex geometries from high vacuum to atmospheric pressure

Christoph Hollenstein, Alan Howling, Ralph Schnyder

The demand for improved performances of power transmission devices requires ever smaller dimensions and higher working voltages which lead to increased risk of breakdown, for example, in satellite slip rings. Previous works are mostly limited to breakdown ...

Iop Publishing Ltd2013

Spectroscopic characterisation of H2 and D2 helicon plasmas generated by a resonant antenna for neutral beam applications in fusion

Basil Duval, Ivo Furno, Alan Howling, Alexander Karpushov, Philippe Frédérique Bruno Guittienne, Rémy Jacquier, Riccardo Agnello, Gennady Plyushchev, Kevin Henricus Annemarie Verhaegh, Claudio Marini

A new generation of neutral beam systems will be required in future fusion reactors, such as DEMO, able to deliver high power (up to 50 MW) with high (800 keV or higher) neutral energy. Only negative ion beams may be able to attain this performance, which ...

IOP Publishing Ltd2017

Analysis of resonant planar dissipative network antennas for rf inductively coupled plasma sources

Christoph Hollenstein, Alan Howling, Philippe Frédérique Bruno Guittienne

The analysis of a radio-frequency (RF) planar antenna is presented for applications in plasma processing. The antenna is a network of elementary meshes composed of inductive and capacitive elements which exhibits a set of resonant modes. The high currents ...

Iop Publishing Ltd2014

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

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

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

Radio frequency breakdown between structured parallel plate electrodes with a millimetric gap in low pressure gases

Christoph Hollenstein, Alan Howling, Boris Legradic

This paper presents an investigation into radio frequency (rf) breakdown for electrodes with holes or protrusions, approximating the situation in real reactors and providing a benchmark for fluid simulations. rf breakdown curves (voltage versus pressure) g ...

American Institute of Physics2010

Negative ion source development for a photoneutralization based neutral beam system for future fusion reactors

Basil Duval, Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne, Rémy Jacquier, Riccardo Agnello, Claudio Marini

In parallel to the developments dedicated to the ITER neutral beam (NB) system, CEA-IRFM with laboratories in France and Switzerland are studying the feasibility of a new generation of NB system able to provide heating and current drive for the future DEMO ...

Iop Publishing Ltd2016

Multiple dehydrogenation reactions of negative ions in low pressure silane plasma chemistry

Christoph Hollenstein, Alan Howling, Antoine Descoeudres

Micro-particle formation in low pressure silane (SiH4) plasmas has been of technical interest and concern for at least 40 years. Negative ion plasma chemistry is a candidate for the initial nucleation, which has been extensively studied both experimentally ...

2020

Industrial plasmas in academia

Christoph Hollenstein, Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne

The present review, written at the occasion of the 2014 EPS Innovation award, will give a short overview of the research and development of industrial plasmas within the last 30 years and will also provide a first glimpse into future developments of this i ...

Iop Publishing Ltd2015

Low ion energy RF reactor using an array of plasmas through a grounded grid

Christoph Hollenstein, Alan Howling, Michaël Chesaux

A reactor using localized remote plasma in a grid electrode is presented in this study. The aim is to reduce the ion bombardment energy inherent in RF capacitively coupled parallel plate reactors used to deposit large area thin film silicon solar cells. Hi ...

A V S Amer Inst Physics2013

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

Ivo Furno, Alan Howling, Philippe Frédérique Bruno Guittienne, 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

Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

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

A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmis ...

2017