Patent ID: 8492978

Claim:
An electron beam tube comprising: a tube body; a cathode mechanically affixed to the tube body through an insulating element and configured to emit an electron beam comprising an operating electron beam current, wherein the cathode is connected to a cathode biasing circuit adapted to apply a bias voltage to the cathode; an anode affixed to the tube body through an insulating element and held in proximity to the cathode, wherein the anode is connected to an anode bias circuit adapted to apply a bias voltage to the anode; a focusing electrode mechanically affixed to the tube body through an insulating element and held in proximity to the cathode and the anode, wherein the focusing electrode is connected to a focusing electrode bias circuit adapted to apply a bias voltage to the focusing electrode; and a switching mechanism configured to change a voltage bias applied to at least two of the cathode, the anode, and the focusing electrode, such that the operating electron beam current is reduced to be substantially equal to zero; wherein the switching mechanism comprises a first switch that is operatively coupled to the cathode bias circuit and a second switch that is operatively coupled to the focusing electrode bias circuit, such that upon actuation of the switching mechanism, a bias voltage applied to the cathode is changed and a bias voltage applied to the focusing electrode is changed; wherein the switching mechanism further comprises a third switch that is operatively coupled to the anode bias circuit, such that upon actuation of the switching mechanism, a bias voltage applied to the anode is changed and a bias voltage applied to the focusing electrode is changed.