Gate offset and emitter design effects of triode cold cathode electron beams on focal spot sizes for x-ray imaging techniques

We report on the structural effects of a carbon nanotube based cold cathode electron beam (C-beam) module on focal spot sizes (FSSs) for high resolution x-ray imaging applications without additional focusing components. A simple combination of vertically aligned carbon nanotubes and gate mesh structure achieved FSS of 252 and 410 μm for longitudinal and transverse directions, respectively. As design parameters of the modules, gate offsets, gate hole pitch, and emitter area effects of C-beam modules on FSS were optimized. We expect that our simple but sophisticated C-beam module structure will pave next generation x-ray devices not only for high quality x-ray imaging but cost-effective ways for mass production.