ABSTRACT
The field emission miniature X-ray tubes (FE-MXT) are cutting-edge applications of nanotechnology, with massive potential in medicine and biology, as well as in microelectronics. One important aspect of MXTs is related to the resolution in X-ray imaging. X-rays are generated by striking the metal target with accelerated electrons. MXTs would, thus, promise fine image resolution never attained to date with bulky X-ray tubes. Field-electron emission, abbreviated as “field emission”, is a quantum mechanical process of electron tunneling; free electrons at the Fermi level in a non-insulating solid tunnel through the potential barrier sloped at the negatively biased surface. Medical X-ray tubes currently in use are mostly of diode type. In diode tubes, the electron current is solely controlled by the potential difference between cathode and anode. In FE X-ray tubes, the electron current is exponentially dependent on the inter-electrode potential, so a slight increase in the potential leads to a great increase in the electron current output, and vice-versa.
