Ion Effects and Ion Elimination in the Cornell ERL

In an energy recovery linac (ERL) where beam-loss has to be minimal, and where beam positions and emittances have to be very stable in time, optic errors and beam instabilities due to ion effects have to be avoided. Possibly the least unattractive way of eliminating ions in an ERL is the installation of clearing electrodes. We present calculations of the remnant ion density and its effect on the beam.