Particle-in-cell simulations of plasma accelerators and electron-neutral collisions - art. no. 101302

We present 2D simulations of both beam- driven and laser- driven plasma wak efield accelerators, using the object- oriented particle- in- cell code XOO PIC, which is time explicit, fully electromagnetic, and capable of running on massively parallel supercomputers. Simulations of laser- driven wakefiel ds with low (similar to 10(16) W/cm(2) ) and high (similar to 10(18) W/cm(2 )) peak intensity laser pulses are conducted in slab geometry, showing agre ement with theory and fluid simulations. Simulations of the E- 157 beam wak efield experiment at the Stanford Linear Accelerator Center, in which a 30 GeV electron beam passes through 1 m of preionized lithium plasma, are cond ucted in cylindrical geometry, obtaining good agreement with previous work. We briefly describe some of the more significant modifications to XOOPIC r equired by this work, and summarize the issues relevant to modeling relativ istic electron- neutral collisions in a particle- in- cell code.