Quasi-monoenergetic electron beams from a few-terawatt laser driven plasma acceleration using a nitrogen gas jet

An experimental investigation on the laser plasma acceleration of electrons has been carried out using 3 TW, 45 fs duration titanium sapphire laser pulse interaction with a nitrogen gas jet at an intensity of 2 × 1018 W cm−2. We have observed the stable generation of a well collimated electron beam with divergence and pointing variation ∼10 mrad from nitrogen gas jet plasma at an optimum plasma density around 3 × 1019 cm−3. The energy spectrum of the electron beam was quasi-monoenergetic with an average peak energy and a charge around 25 MeV and 30 pC respectively. The results will be useful for better understanding and control of ionization injection and the laser wakefield acceleration (LWFA) of electrons in high-Z gases and also towards the development of practical LWFA for various applications including injectors for high energy accelerators.