Two-dimensional dynamics of the plasma wakefield accelerator

The plasma wakefield accelerator (PWFA) is an accelerator concept based on utilizing a large amplitude plasma wave to accelerate relativistic electrons to ultra-high energy. The plasma wave represents the wave produced by a relativistic beam as it passes through a cold plasma. As the beam enters the plasma its space charge polarizes the background. When the beam tail passes the plasma is left with a large oscillating induced charge. The wakefields are derived assuming that the charge and current profiles of the driving bunch remain fixed. An estimate is made of the condition necessary for maintaining the profile of the driving bunch. The current required to result in an accelerating field approaching the wavebreaking limit is estimated. The beam dynamics for a small beam are simulated based on these estimates. The results of the studies reported indicate that the self-consistent transverse motion of the driving bunch makes pulse tailoring impossible to maintain. 4 refs., 5 figs