A scheme for a coherently controlled pulsed electron gun

When the outer electron of an alkali atom in an electric field is laser excited just above the field-induced ionization threshold, the electron ejection will not be instantaneous. Calculations show there are a number of energy regions where, upon short-pulse laser excitation, the atom will eject a train of electron probability pulses with the pulses being nearly equally spaced in time. This system can be the source of a picosecond pulsed electron gun. We show that it is possible to coherently control the electron pulse frequency while the pulse train is being emitted.