Study of Condensable Ion Production by Resonant Laser Ionization

Abstract : This doctoral thesis describes the implementation, optimization and development of a Resonant Ionization Laser Ion Source (RILIS) at the GANIL facility (Caen, France). The RILIS is a selective ion source technique which is based on a step-wise resonant excitation process where the elements of interest are ionized via atomic resonant excitation by laser radiation. The off-line RILIS test bench at GANIL consists of three tunable titanium:sapphire lasers and a hot-cavity ion source. In this thesis, a new three-step Zn ionization scheme was developed and the already known ionization schemes for Sn have been compared in order to identify the best ionization scheme for a titanium:sapphire laser system. Furthermore, several configurations of the ion source geometry were tested (two diameters and two lengths) in order to provide an optimal ionization efficiency and ion beam emittance. An increasing of the ionizer diameter was found to enhance the production of laser ionized elements, while no enhancement was observed by modifying the ionizer length. The time-of-flight of the generated ions was also studied for the different ion source configurations at several temperatures. The time-of-flight can provide crucial information about the ion formation inside the ion source cavity. In addition, a technique to measure the convolution of the spatial and energetic spread of the ion bunches at the detection point was developed. Finally, two contamination reduction techniques were studied: Firstly, the ions trajectories through the ion source cavity can be modified by the electric field generated due to resistive heating. Therefore, a study of the appropriate configuration of the electric field direction was performed to reduce the alkali contamination of the ion beam. Secondly, a low work function material was tested in order to reduce the production of alkali contaminants and molecular sidebands generated inside the ion source.
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Submitted on : Wednesday, May 11, 2016 - 9:45:56 AM
Last modification on : Thursday, February 1, 2018 - 1:33:46 AM
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  • HAL Id : tel-01314260, version 1

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Jose Luis Henares Gonzalez. Study of Condensable Ion Production by Resonant Laser Ionization. Accelerator Physics [physics.acc-ph]. Normandie Université, 2016. English. ⟨tel-01314260⟩

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