Energy tuner for a gated field emission cathode device, and associated method

A tunable field emission cathode device, comprising:

• a cathode element having a field emission surface and being electrically-connected to ground;
• a gate electrode element disposed in spaced-apart relation to the field emission surface of the cathode element so as to define a first gap therebetween, the gate electrode element being arranged to have a gate voltage applied thereto by a gate voltage source to form a first electric field about the gate electrode element within the first gap, the field emission surface emitting electrons in response to the first electric field, the electrons emitted from the field emission surface being accelerated by the first electric field through the gate electrode element;
• an anode element spaced apart from the cathode element, with the gate electrode element disposed therebetween, the anode element being arranged to have an anode voltage applied thereto by an anode voltage source to form a second electric field about the anode element, the second electric field attracting the electrons emitted through the gate electrode element;
• and
• a tuning electrode element disposed in spaced-apart relation to the gate electrode element, between the gate electrode element and the anode element, so as to define a second gap therebetween, the tuning electrode element being arranged to have a tuning voltage applied thereto by a tuning voltage source to form a third electric field about the tuning electrode element, the electrons directed through the gate electrode element being decelerated by the third electric field and directed through the tuning electrode element toward the anode element,
• wherein the gate voltage source is configured to apply a positive voltage to the gate electrode element and the tuning voltage source is configured to apply a negative voltage to the tuning electrode element, and wherein the tuning voltage applied by the tuning voltage source is variable in relation to the gate voltage applied by the gate voltage source to attenuate an energy and a waveform of the electrons directed through the tuning electrode element over a time period.