The generation of an ultrashort relativistic electron bunch from a strong laser-plasma interaction have been studied by particle-in-cell simulations and observed experimentally. The electron beam was generated from the plasma created by focusing 12 TW (tera watt) laser pulse at the edge of helium gas jet expanded into the vacuum from a pulsed supersonic nozzle. The laser pulse duration was 50∼fs (femtosecond). In the interaction of 50 fs, 12 TW laser pulse with plasma of density of 5 ×
10^{19}
cm
^{-3}
, the electron generation was observed in the simulation at the very beginning of the interaction region. The plasma electrons were gaining higher energies by the huge longitudinal electric fields (created by the laser pulse) as they move through the rest of the plasma following the laser pulse. In the experiment, the electron beam transverse profile and its total charge have been measured in the forward direction (the same direction of the laser pulse) by using imaging plate and Faraday-cup, respectively.
