LATERAL TRANSPORT OF FAS T ELECTRONS IN HIGH- INTENSITY LASER-PLASMA INTERACTIONS

Lateral fast electron transport in intense laser-plasma interactions has been studied. The lateral electron transport is identified by multipeak distributions of the fast electrons emitted along the front and rear target surfaces. PIC simulations shown that this is induced by the spontaneous electrostatic and magnetic fields. The fields at the target surface can be us ed to confine and guide fast electron propagation with shaped targets. Transport of fast electrons in the interaction of ultrashort high-intensity laser pulses with targets have attracted great interests due to their potential applications in fast ignition scheme for inertial confined fusion(1). Besides the longitudinal transport into the high density plasma regions, lateral transport of hot electrons along target surfaces has also identified by observation of x-ray(2,3) and ion emissions (4). Such surface transport has been used to explain why a re-entry cone target can increase the neutron yield by three orders than that from a plane target (5,6,7). In our previous experiments we have observed a distinct fast electron beam emitted along the target surface for large laser incidence angles (8). In this paper, we have demonstrated that the fast electron beams can also be emitted along the target surface due to the lateral transport for moderate incidence angles. This transport and the spontaneous electrostatic and magnetic fields can be used to guide fast electron propagation with shaped targeted. The experiments were carried out using the Xtreme Light II (XL-II) laser system at the Institute of Physics, Chinese Academy of Sciences. The laser system can produce a linearly polarized pulse with energy up to 500 mJ in a duration of 30 fs at a wavelength of 800 nm. The amplified spontaneous emission (ASE) was measured to be ~10-5 of the peak intensity of