This thesis documents the study of elementary processes in interaction of intense, ultrashort
laser pulses with underdense plasmas. Main objective of this thesis is to understand the
basic phenomena resulting from the interaction of ultra-short ultra-intense laser pulses with
matter and to study the mechanism which eventually leads to generation of high energetic
electrons, in laser based plasma accelerators. In a broad prospective, the work here can be
described as a detailed experimental and numerical study of laser matter interaction, plasma formation and acceleration of particles. The motivation for these experiments arises from
the fact that the results are relevant from both fundamental and applied research point of
view.