Enhanced transport of relativistic electrons through nanochannels

Abstract

Efficient transport of fast electrons driven by intense laser solid interaction depends crucially on optimal target design. We demonstrate a hybrid target design that incorporates two important features—efficient generation of relativistic electrons and their unimpeded transport in dense media. The target was fabricated on a porous alumina base consisting of an array of sublambda cylindrical holes partially filled with Cu nanorods, such that light field propagates in the hollow channels, located ahead of the metallic fillings. The hollow array acts as an efficient source of hot electrons when driven by relativistically intense, femtosecond laser pulses and shows a 60-fold enhancement in electron flux compared to a solid target. This enhancement is ascribed to an increased penetration of laser through subwavelength pores and enhanced local electric fields. The metal doped part facilitates efficient transport of the generated electrons, due to its large background conductivity. A 4-fold enhancement in target rear side electron flux is observed compared with unfilled porous alumina.