| Plasma based electron beam sources, which are now under development, will produce beams with much higher particle densities than are currently available. Plasma sources can create beams with brightness (the measure of achievable beam density) orders of magnitude greater than radio frequency photoinjectors, the current state-of-the-art. Plasma density transition trapping is one example of the many plasma electron beam source schemes under development. Plasma density transition trapping is a recently proposed self-injection mechanism for plasma wake field accelerators. The technique uses a sharp downward plasma density transition to trap and accelerate background plasma electrons in a plasma wake field.;This dissertation examines the different regimes in which plasma density transition trapping can operate and the quality of the electron beams captured in terms of emittance, energy spread, and brightness. This is accomplished using two-dimensional Particle-In-Cell (PIC) simulations which show that the captured beam parameters can be optimized by manipulating the overall plasma density, as well as the density profile. A general set of scaling laws is developed that predicts how the brightness of transition trapping beams, or the beams produced by any plasma system, scales with the plasma density. These scaling laws predict that beam brightness increases linearly with the plasma density of the source.;The design and execution of the first plasma density transition trapping experiment is also documented in this dissertation. Plasma with density on the order of 1013 cm−3 was used in the experiment. Plasma density transitions steep enough to produce trapping at this density were created and measured. Interaction between the plasma transition and a driving electron beam pulse did not, however, produce trapped electrons. Detailed measurements of the drive beam parameters revealed that it did not meet the trapping experiment design criteria. Simulations using the measured plasma and beam parameters predict zero captured charge in agreement with observations. |
