Plasma density transition trapping and acceleration of plasma electrons in a plasma wakefield

Summary form only given. Plasma density transition trapping is a proposed self-injection scheme for plasma wakefield accelerators. This technique uses a sharp downward plasma density transition to trap and accelerate background plasma electrons in a plasma wakefield. A proof-of-principle experiment designed to demonstrate this type of injection is underway at the Fermilab NICADD Photoinjector Laboratory. The goal of experiment is to capture a /spl sim/100 pC beam with /spl sim/4% rms energy spread out of a 2/spl times/10/sup 13/ cm/sup -3/ peak density plasma using a 14 MeV drive beam of charge 6-12 nC. We report on initial particle trapping results.