A4 Article in conference proceedings
Photo-assisted O− and Al− production with a cesium sputter ion source (2021)

Tarvainen, O., Kronholm, R., Laitinen, M., Reponen, M., Julin, J., Toivanen, V., Napari, M., Marttinen, M., Kalvas, T., Faircloth, D., Koivisto, H., & Sajavaara, T. (2021). Photo-assisted O− and Al− production with a cesium sputter ion source. In Y. Belchenko, D. Faircloth, S. Lawrie, O. Tarvainen, & M. Wada (Eds.), NIBS 2020 : Seventh International Symposium on Negative Ions, Beams and Sources (Article 020001). American Institute of Physics. AIP conference proceedings, 2373. https://doi.org/10.1063/5.0057495

JYU authors or editors

Publication details

All authors or editors: Tarvainen, Olli; Kronholm, Risto; Laitinen, Mikko; Reponen, Mikael; Julin ,Jaakko; Toivanen, Ville; Napari, Mari; Marttinen, Miha; Kalvas, Taneli; Faircloth, Dan; et al.

Parent publication: NIBS 2020 : Seventh International Symposium on Negative Ions, Beams and Sources

Parent publication editors: Belchenko, Yuri; Faircloth, Dan; Lawrie, Scott; Tarvainen, Olli; Wada, Motoi

Place and date of conference: Online/ Oxford, United Kingdom, 1.-10.9.2020

eISBN: 978-0-7354-4109-5

Journal or series: AIP conference proceedings

ISSN: 0094-243X

eISSN: 1935-0465

Publication year: 2021

Number in series: 2373

Article number: 020001

Publisher: American Institute of Physics

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1063/5.0057495

Publication open access: Not open

Publication channel open access: 

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/77325

Abstract

It has been recently proposed that the production of negative ions with cesium sputter ion sources could be enhanced by laser-assisted resonant ion pair production. We have tested this hypothesis by measuring the effect of pulsed diode lasers at various wavelengths on the O− and Al− beam current produced from Al2O3 cathode of a cesium sputter ion source. The experimental results provide evidence for the existence of a wavelength-dependent photo-assisted enhancement of negative ion currents but cast doubt on its alleged resonant nature as the effect is observed for both O− and Al− ions at laser energies above a certain threshold. The beam current transients observed during the laser pulses suggest that the magnitude and longevity of the beam current enhancement depends on the cesium balance on the cathode surface. It is shown that the ions produced by the laser exposure originate from slightly different potential than the surface produced ions, which allows us to constrain the underlying physical mechanisms. It is concluded that the photo-assisted negative ion production could be of practical importance as it can more than double the extracted beam current under certain operational settings of the cesium sputter ion source. We discuss experiments designed to confirm or dispute the relevance of the ion pair production for negative ion production with cesium sputter ion sources and the possibility of ion pair production explaining the beneficial effect of xenon admixture on the negative ion yield of an RF-driven H− ion source.

Keywords: particle accelerators; ions; laser technology

Contributing organizations

Ministry reporting: Yes

VIRTA submission year: 2021

JUFO rating: 1