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Multilayer graphene sheets were prepared by heat treatment of polyimide films at temperatures of up to 3000 °C. The sheets consist of highly oriented graphite layers with excellent mechanical robustness and flexibility. Key features of these sheets include their high thermal conductivity in the in-plane direction, good mechanical properties, and high carbon purity. The results suggest that the multilayer graphene sheets have great potential for charge stripping foils that persist even under the highest ion beam intensities irradiation and can be used for accelerator applications. [ABSTRACT FROM AUTHOR]

Using the transmission-line theory, we investigate properties of wave propagation and resonance in a pre-Cantor multilayer called pre-Cantor bars whose interval is [0,L]. When the stage number n increases, the pre-Cantor bar will not transmit almost anywhere for [variant_greek_epsilon]r2 > 1 where [variant_greek_epsilon]r2 is the ratio of dielectric constants of two kinds of layers. For resonance frequencies of the n-th pre-Cantor bar, the largest amplitude of voltage at the midpoint of the bar, V(L2), increases double-exponentially because of the inequality |V(L2)|≤[variant_greek_epsilon]r22n-2. For such a resonance frequency, the amplitude of the voltage at the midpoint of an interval [L3k+1,2L3k+1] is given by |V(L2·3k)|≤[variant_greek_epsilon]r22n-k-2 where k = 1,2, ..., n - 1. Because the voltage |V(x)| is localized around x = L2, the electro-magnetic wave (EM) localization occurs for the resonance frequencies of the pre-Cantor bar of the higher stages. Using a microstripline of the 3rd stage Cantor structure we will show that the measured transmission spectrum is consistent with the ideal one if the dissipation factor of the substrate is tan δ = 0.023 that is a typical value for the substrate of glassy epoxy resin in microwave frequencies. [ABSTRACT FROM AUTHOR]