X-ray wakefield acceleration in a nanotube

Electrons can be accelerated to high energies in the wakefield when a short pulse laser or beam passes through a plasma [1]. Experiments have shown that the GeV energy can be obtained over centimeter acceleration in gas plasma with the optical laser. Laser wakefield theory shows that for a given laser the energy gain is inversely proportional to the plasma density and low density implies a much longer acceleration length, which means the scheme of ultrahigh energy gain wakes the acceleration length longer. The recent proposed generation of the X-ray laser pulse provides us an attractive way to get ultrahigh energy [2]. Due to the much higher critical density for the X-ray laser pulse, solid density materials can be chosen, which causes stronger wakefield and ultrahigh energy gain with a compact structure [3]. Motivated by this, we explore the X-ray wakefield accelerator in a nanotube and get the scalings of acceleration.\\[4pt] [1] T. Tajima, J.M. Dawson, Phys. Rev. Lett. \textbf{43}, 267 (1979).\\[0pt] [2] G. Mourou, et al., Eur. Phys. J. \textbf{223}, 1181 (2014).\\[0pt] [3] T. Tajima, Eur. Phys. J. \textbf{223}, 1037 (2014).