Fast microfocus cold cathode x-ray tube based on carbon nanotube array

A cold cathode x-ray tube based on carbon nanotube (CNT) with a vertically-aligned morphology has been fabricated for miniature X-ray source application. The vertically-aligned carbon nanotube was grown by microwave plasma enhanced chemical vapor deposition method. A maximum emission current of 200
$\mu \mathrm{A}$
is achieved with a maximum current density of more than 10 A/cm
²
from the CNT emitter. We have optimized the beam convergence on the target of the microfocus X-ray tube and a focal spot size of 5 μm was achieved. X-ray images of JIMA card, chips, multilayer printed circuit board and field programmable gate array were demonstrated with approximately 5 μm width.