  The properties of the electron source define the ultimate limit of the beam
quality in linear accelerators like Free Electron Lasers (FEL). The goal is to
develop an electron gun delivering beam emittance lower than current state of
the art. Such a gun should reduce the cost and size of an X-ray Free Electron
Laser (XFEL). In this paper we present two concepts of field emitter cathodes
which could potentially produce low emittance beam. The first challenging
parameter for such cathode is to emit peak current as high as 5 A. This is the
minimum current requirement for the XFEL concept from Paul Scherrer Institut.1
Maximum current of 0.12 A and 0.58 A have been reached respectively with field
emitter arrays (FEA) and single needle cathodes. Laser assisted field emission
gave encouraging results to reach even higher peak current and to pre-bunch the
beam.
