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Alan Howling

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Publications associées (70)

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

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

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

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

Alan Howling, Ivo Furno, 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

Gas breakdown mitigation in satellite slip rings

Alan Howling, Ivo Furno, Paul Jeroen Laureis Martens, Fabio Avino

Direct current (DC) gas breakdown is experimentally investigated for high-voltage circular conductors and insulators that reproduce the main features of a satellite slip ring. Breakdown voltages are measured in the pressure range 10 ...

2019

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

Two-fluid plasma model for radial Langmuir probes as a converging nozzle with sonic choked flow, and sonic passage to supersonic flow

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno

Using the Lambert function, Guittienne et al. [Phys. Plasmas 25, 093519 (2018)] derived two-fluid solutions for radial Langmuir probes in collisionless and isothermal plasma. In this Brief Communication, we point out the close analogy with classical compre ...

American Institute of Physics (AIP)2019

RF bias to suppress post-oxidation of mu c-Si:H films deposited by inductively-coupled plasma using a planar RF resonant antenna

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

One challenge for microcrystalline silicon (mu c-Si:H) deposition is to achieve high deposition rates while maintaining high quality films. In this work, an inductively-coupled plasma (ICP) is used to deposit mu c-Si:H on glass substrates by means of a nov ...

2018

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

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

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- ...

2018

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

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno

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

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

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

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

Ion heating and flows in a high power helicon source

Alan Howling, Ivo Furno, Gennady Plyushchev, Rémy Jacquier, Riccardo Agnello

We report experimental measurements of ion temperatures and flows in a high power, linear, magnetized, helicon plasma device, the Resonant Antenna Ion Device (RAID). Parallel and perpendicular ion temperatures on the order of 0.6 eV are observed for an rf ...

Amer Inst Physics2017

Complex image method for RF antenna-plasma inductive coupling calculation in planar geometry: II. Measurements on a resonant network (vol 24, 065015, 2015)

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

Iop Publishing Ltd2017

Helicon wave-generated plasmas for negative ion beams for fusion

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

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 ...

2017

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

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno, 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

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

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

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

Method and device for determining plasma characteristics

Philippe Frédérique Bruno Guittienne, Alan Howling, Ivo Furno

The invention relates to a method and a device for determining plasma characteristics, the method comprising the steps of: - arranging a measurement probe (2) having a self-inductance in proximity to a plasma (3) to establish inductive coupling between the ...

2016

Industrial plasmas in academia

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

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

Complex image method for RF antenna-plasma inductive coupling calculation in planar geometry. Part I: basic concepts

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

The coupling between an inductive source and the plasma determines the power transfer efficiency and the reflected impedance in the primary circuit. Usually, the plasma coupling is analysed by means of a transformer equivalent circuit, where the plasma ind ...

Iop Publishing Ltd2015

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