  In the framework of the Low Emittance Gun (LEG) project, high gradient
acceleration of a low emittance electron beam will be necessary. In order to
achieve this acceleration a -500 kV, 250 ns FWHM, pulse will be applied in
between two electrodes. Those electrodes should sustain the pulsed field
without arcing, must not outgass and must not emit electrons. Ion back
bombardment, and dark current will be damageable to the electron source as well
as for the low emittance beam. Electrodes of commercially available OFE copper,
aluminium, stainless steel, titanium and molybdenum were tested following
different procedures including plasma glow discharge cleaning.
