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Cold atomic beam ion source for focused ion beam applications



Brenton J. Knuffman, Adam V. Steele, Jabez J. McClelland


We report measurements and modeling performed on an ion source based on ionization of a laser-cooled atomic beam. We show a high brightness and a low energy spread, suitable for use in next-generation, high-resolution focused ion beam (FIB) systems. Our measurements of total ion current as a function of ionization conditions support a model that also predicts the cross-sectional current density and spatial distribution of ions created in the source. The model predicts a peak brightness of 2×107 Am 2sr 1eV 1 and an energy spread < 0.34 eV. The model is also combined with Monte-Carlo simulations of the inter-ion Coulomb forces to show that the source can be operated at several picoamperes with a brightness above 1×107 Am 2sr 1eV 1. We estimate that when combined with a conventional ion focusing column, an ion source with these properties could focus a 1 pA beam into a spot smaller than 1 nm. A total current greater than 5 nA was measured in a lower-brightness configuration of the ion source, demonstrating the possibility of a high current mode of operation.
Japanese Journal of Applied Physics


focused ion beams, cold atoms, laser cooling


Knuffman, B. , Steele, A. and McClelland, J. (2013), Cold atomic beam ion source for focused ion beam applications, Japanese Journal of Applied Physics, [online], , (Accessed July 21, 2024)


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Created July 22, 2013, Updated October 12, 2021