Guiding of highly charged ions through tilted capillaries promises to develop into a tool to efficiently collimate and focus low-energy ion beams to sub-micrometer spot size. One control parameter to optimize guiding is the residual electrical conductivity of the insulating material. Its strong, nearly exponential temperature dependence is the key to transmission control and can be used to suppress transmission instabilities arising from flux fluctuations of incident ions which otherwise would lead to Coulomb blocking of the capillary. We demonstrate the strong dependence of transmission of Ar 7+ ions through a single macroscopic glass capillary on temperature and ion flux. Results in the regime of dynamical equilibrium can be described by balance equations in the linear-response regime.

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PACS 34.35.+a-Interactions of atoms and molecules with surfaces PACS 79.20.-m-Impact phenomena (including electron spectra and sputtering) PACS 68.49.Sf-Ion scattering from surfaces (charge transfer, sputtering, SIMS) Abstract-We report the formation of nano-sized pits on poly(methyl methacrylate) after exposure to slow highly charged ion beams. The pits are formed on the polymer surface as a direct result of individual ion impacts. Intermittent contact mode atomic-force microscopy was employed to study the size evolution of the pits in dependence of potential and kinetic energies of the incident ions. A potential energy threshold value of approximately 7 keV was found for pit formation. Above this value an increase in potential energy results in an increasing pit volume, while the pit shape can be tuned by varying the kinetic energy.

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