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Étude d'une source d'ions obtenue par extraction et accélération à partir d'une source plasma filaire

Abstract : In this study we first model a DC low pressure wire plasma source and then characterize the properties of an ion gun derived from the plasma source. In order to study the properties of the derived ion gun, we develop a particle-in-cell code fitted to the modelling of the wire plasma source operation, and validate it by confrontation with the results of an experimental study. In light of the simulation results, an analysis of the wire discharge in terms of a collisional Child-Langmuir ion flow in cylindrical geometry is proposed. We interpret the mode transition as a natural reorganisation of the discharge when the current is increased above a threshold value which is a function of the discharge voltage, the pressure and the inter-electrodes distance. In addition, the analysis of the energy distribution function of ions impacting the cathode demonstrates the ability to extract an ion beam of low energy spread around the discharge voltage assuming that the discharge is operated in its high pressure mode. An ion source prototype allowing the extraction and acceleration of ions from the wire source is then proposed. The experimental study of such a device confirms that, apart from a shift corresponding to the accelerating voltage, the acceleration scheme does not spread the ion velocity distribution function along the axis of the beam. It is therefore possible to produce tunable energy (0-5 keV) ion beams of various ionic species presenting limited energy dispersion (~ 10 eV). The typical beam currents are about a few tens of micro-amperes, and the divergence of such a beam is on the order of one degree. A numerical modelling of the ion source is eventually conducted in order to identify potential optimizations of the concept.
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https://pastel.archives-ouvertes.fr/pastel-00646821
Contributor : Renaud Gueroult <>
Submitted on : Wednesday, November 30, 2011 - 5:51:06 PM
Last modification on : Friday, October 16, 2020 - 3:21:33 AM
Long-term archiving on: : Friday, November 16, 2012 - 12:35:10 PM

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  • HAL Id : pastel-00646821, version 1

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Renaud Gueroult. Étude d'une source d'ions obtenue par extraction et accélération à partir d'une source plasma filaire. Physique des plasmas [physics.plasm-ph]. Ecole Polytechnique X, 2011. Français. ⟨pastel-00646821⟩

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