Measuring the thickness of carbon stripper foils using electron microscopy images
To date, research focused on the development and improvement of manufacturing methods for thin-film stripper foils used in accelerator technology to extract accelerated ion beams is of particular importance. One of the priorities is to increase the service life of such foils, which is associated with the significant complexity of the replacement process. This work is devoted to the experimental determination using electron microscopy methods of the thickness of a carbon film produced by vacuum-arc deposition of carbon on a glass substrate as a result of spraying a graphite rod. Samples of a carbon film, both in the initial state and exposed to an accelerated electron beam, were considered as objects of analysis. For a preliminary assessment of the surface density of the manufactured foil, the gravimetric method was used, while the assumption was made about the uniformity of carbon deposition on the surface. The analysis of the studied samples was carried out using two approaches based both on the analysis of electron microscopic images obtained when the object was positioned in a plane perpendicular to the direction of the main electron beam, and on measurements when the object was placed on a slide table mounted at an angle of 52° with respect to the direction of the primary electron beam. The obtained images clearly show two formed film layers with a thickness from 0.4 to 0.9 μm, while the total film thickness ranged from 1.2 to 2.0 μm with an average value of 1.4 μm. The density of the film material was also calculated, which turned out to be slightly higher than the density of carbon black and less than the density of graphite. The results obtained by the two methods for determining the thickness of the sample are consistent with each other, and also correspond to the calculated thickness of the film.
Authors: Z. G. Lyullin, S. A. Trifonov, S. V. Grigorenko, D. K. Kostrin
Direction: Physics
Keywords: stripper foil, cyclotron accelerator, surface structure, surface density, electron microscopy, layer thickness
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