Electron optics simulations of CNT-based x-ray source operating at low gate voltage

It is crucial to develop a CNT-based x-ray source operating at low gate voltage with high emission current density. We have performed electron optics simulations for a few potentially effective structures. For higher emission current at lower gate voltage, it is desirable to use an emitter shape with higher field enhancement factor. We have devised a structure with line emitters with a rectangular cross-section located at the center of gate opening. Extensive electron optics simulations showed that it operates at considerably lower voltages than the structure with flat emitter. Geometrical parameters including mesh gate opening size, and the width and height of emitter have been optimized. The optimum values were determined by compromising the emission current and the gate transmission rate.