Laser wakefield acceleration and plasma collisions: What they are, how the two relate, and methods of simulation
Date:
Laser wakefield acceleration (lwfa) is a means of accelerating electrons to energies up to several GeV. It is becoming an attractive experimental tool because it can produce electron bunches comparable to large facilities like SLAC or CERN in a few centimeters versus several kilometers. Additionally, with the advancement of laser technology, we are now reaching a point where we can create denser plasmas, which, combined with lwfa electron bunches, leads to collisions and collisional ionization effects that become important. In this talk, I will give a brief overview of laser wakefield acceleration: how it is accomplished, how it compares to the alternative rf means of accelerating particles, and its future prospects. Then, I will discuss the physics and computational methods behind collisions and collisional ionization within plasmas. In particular I will focus on the models I am implementing to realize this physics within the particle-in-cell code OSIRIS, i.e. a modified binary encounter Bethe model to calculate collisional cross-sections and the approach proposed by Pérez (2012) to implement the collisional interactions. Finally, I will discuss the propagation of high-energy, high-density electron bunches in air and how collisions (and other effects) may play an important role in helping or hindering the total distance they can travel.