An apparatus and method for controlling electron flow within a plasma to produce a controlled electron beam is provided. A plasma is formed between a cathode and an acceleration anode. A control anode is connected to the plasma and to the acceleration anode via a switch. If the switch is open, the ions from the plasma flow to the cathode and plasma electrons flow to the acceleration anode. With the acceleration anode suitably transparent and negatively biased with a DC high voltage source, the electrons flowing from the plasma are accelerated to form an electron beam. If the switch is closed, the ions still flow to the cathode but the electrons flow to the control anode rather than the acceleration anode. Consequently, the electron beam is turned off, but the plasma is unaffected. By controlling the opening and closing of the switch, a controlled pulsed electron beam can be generated.