SCHEME FOR A COHERENTLY CONTROLLED PULSED ELECTRON-GUN

When the outer electron of an alkali atom in an electric field is lase r excited just above the field-induced ionization threshold, the elect ron 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 pulse s being nearly equally spaced in time. This system can be the source o f a picosecond pulsed electron gun. We show that it is possible to coh erently control the electron pulse frequency while the pulse train is being emitted. (C) 1998 Optical Society of America.