Role of lattice structure and low temperature resistivity on fast electron beam filamentation in carbon

Dance, R J and Butler, N M H and Gray, R J and MacLellan, D A and Rusby, D R and Scott, G G and Zielbauer, B and Bagnoud, V and Xu, H and Robinson, A P L and Desjarlais, M P and Neely, D and McKenna, P (2015) Role of lattice structure and low temperature resistivity on fast electron beam filamentation in carbon. Plasma Physics and Controlled Fusion, 58 (1). 014027. ISSN 0741-3335

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    Abstract

    The influence of low temperature (eV to tens-of-eV) electrical resistivity on the onset of the filamentation instability in fast-electron transport is investigated in targets comprising of layers of ordered (diamond) and disordered (vitreous) carbon. It is shown experimentally and numerically that the thickness of the disordered carbon layer influences the degree of filamentation of the fast-electron beam. Strong filamentation is produced if the thickness is of the order of 60 μm or greater, for an electron distribution driven by a sub-picosecond, mid-1020 Wcm-2 laser pulse. It is shown that the position of the vitreous carbon layer relative to the fast-electron source (where the beam current density and background temperature are highest) does not have a strong effect because the resistive filamentation growth rate is high in disordered carbon over a wide range of temperatures up to the Spitzer regime.