  In this dissertation, a fully object-oriented, fully relativistic,
multi-dimensional Particle-In-Cell code was developed and applied to answer key
questions in plasma-based accelerator research. The simulations increase the
understanding of the processes in laser plasma and beam-plasma interaction,
allow for comparison with experiments, and motivate the development of
theoretical models.
  The simulations support the idea that the injection of electrons in a plasma
wave by using a transversely propagating laser pulse is possible. The beam
parameters of the injected electrons found in the simulations compare
reasonably with beams produced by conventional methods and therefore laser
injection is an interesting concept for future plasma-based accelerators.
  Simulations of the optical guiding of a laser wakefield driver in a parabolic
plasma channel support the idea that electrons can be accelerated over
distances much longer than the Rayleigh length in a channel. Simulations of
plasma wakefield acceleration in the nonlinear blowout regime give a detailed
picture of of the highly nonlinear processes involved. Using OSIRIS, we have
also been able to perform full scale simulations of the E-157 experiment at the
Stanford Linear Accelerator Center. These simulations have aided the
experimentalists and they have assisted in the development of a theoretical
model that is able to reproduce some important aspects of the full PIC
simulations.
  Update (2015): This dissertation was originally written in 2000. I am making
it now available on arXiv with the hope that some its content might proof
useful to the users of the OSIRIS code which has continued to be utilized by a
number of research groups since it was originally written as part of the
research presented in this dissertation.
