A Simple Method for Damping Transverse Motion of a High Intensity Electron Beam

We describe a simple electrostatic focusing method which efficiently damps transverse motion of a high intensity (both high current and high particle energy) electron beam. The principle is to create an electrostatic central force anharmonic potential field which phase mix damps transverse beam motion into increased beam emittance. The non-linear electrostatic field is created by a very resistive wire (L/ R time ~2 ns) strung axially down the accelerator vacuum pipe. Positive image charge equal to ~1/2 the negative beam charge is induced onto the wire. Since the beam self fields cancel to within 1/γ
²
, the resultant wire electric field dominates. Experimental results showing the guiding, focusing and damping of transverse motion will be presented.