Test Results of the Plasma Source for Underdense Plasma Lens Experiments at the UCLA Neptune Lab

A plasma source was developed at UCLA for planned underdense plasma lens experiments, where the plasma density is less than the electron beam density. The argon plasma, produced by a discharge between a LaB6 cathode at 1330 C and a tantalum anode, is con ned by a solenoidal magnetic eld and ows transversely across the electron beam path. Extensive test of the plasma source is under way for various conditions before it is assembled with the UCLA photocathode-based electron linac. In particular, di erent longitudinal (with respect to the electron beam) plasma pro les and e ective plasma lengths can be obtained by adjusting the moveable sliding door between the plasma source and the transverse beamline. Test results of the plasma source are presented.