Plasma Evolution in Plasma Wakefield Accelerators

An integral part of plasma wakefield acceleration (PWFA) is producing, monitoring, and controlling a plasma source. Understanding the temporal evolution of plasma parameters allows for constraints on experimental lifetime and initial conditions. Recombination factors for low temperature (kBT less than the ionization energy), singly-ionized Argon and Hydrogen plasmas (nominal PWFA plasma sources) are investigated to develop a model of plasma decay. Due to the high density of the plasma sources collisional recombination and ionization dominates radiative processes, and the problem of modelling plasma decay simplifies to finding the recombination coefficients for these plasma sources. This recombination coefficient is presented as a function of plasma temperature to determine plasma decay for a variety of initial plasma conditions. Additionally, plasma temperature is modelled from the ponderomotive force of the ionizing laser pulse. Results are utilized for designing optimal PWFA experiments.