An active current-control unit composed of cascade transistors for extremely stabilizing emission currents from carbon nanotube field emitters

We propose an advanced active current-control (ACC) unit composed of two cascade transistors for extremely stabilizing field emission currents. The upper transistor connected to the cathode modulates high voltages for field emission while the other one regulates emission current stably. Using the ACC unit developed, very stable emission currents were achieved from the fully vacuum-sealed x-ray tube with carbon nanotube field emitters for long pulse sequence. The advanced ACC unit could provide commercial stability and reliability of field emission x-ray sources even in high voltage and/or high duty environments.