Plasma Lens Experiments at the Final Focus Test Beam*

We intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter egime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. WC will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam ionization of a working gas. At an increased bunch population of 2.5 X IO’“, tunneling ionization of a gas target by an electron beam- an effect which has never been observed bcforc- should he significant. The compactness of our device should prove to be of interest for applications at the SLC and the next generation linear colliders. I