Production of collimated MeV electron beam in carbon nanotube array irradiated by super-intense femtosecond laser

A super-intense 30 fs laser pulse (peak power: 286 TW) is focused on a ∼1 mm thick carbon nanotube (CNT) array and a collimated MeV electron beam is detected at rear of CNT array. Most of these fast electrons are in a beam of divergence angle lower than 2° that is one order of magnitude lower than the MeV electron divergence (30-50°) in the general laser-matter interaction experiments. By simulation, we capture the detailed behaviors of fast electrons in CNT array. It is found that the fast electron pulse excites a strong electric field perpendicular to the tube axis in conductive CNT array that guides these ultra-hot electrons to propagate along the CNT and collimates the divergent fast electron beam into a tight beam. These results show a method to generate collimated and even focused MeV electron beams by using CNTs.