  We present a novel concept for the generation of gigahertz repetition rate
high brightness electron bunches. A custom design 100 kV thermionic gun
provides a continuous electron beam, with the current determined by the
filament size and temperature. A 1 GHz rectangular RF cavity deflects the beam
across a knife-edge, creating a pulsed beam. Adding a higher harmonic mode to
this cavity results in a flattened magnetic field profile which increases the
duty cycle to 30%. Finally, a compression cavity induces a negative
longitudinal velocity-time chirp in a bunch, initiating ballistic compression.
Adding a higher harmonic mode to this cavity increases the linearity of this
chirp and thus decreases the final bunch length. Charged particle simulations
show that with a 0.15 mm radius LaB6 filament held at 1760 K, this method can
create 279 fs, 3.0 pC electron bunches with a radial rms core emittance of
0.089 mm mrad at a repetition rate of 1 GHz.
