Compact Piezoelectric Transformer X-ray Source

A compact, lightweight, battery powered x-ray source using a piezoelectric transformer (PT) will be presented. The x-ray source will be used in a back-scatter detector designed for imaging plant root systems in order to determine phenotypical information. Piezoelectric transformers step up an input ac voltage much like their magnetic cousins, in a very compact and power efficient package. Voltage input to the PT induces mechanical strain which couples with a vibrational resonance in the crystal. The resonating piezoelectric crystal can in turn produce large voltage gain across the device. These transformers enable compact high voltage systems to be developed. The PT will feed into a Cockcroft- Walton multiplier (CW) which will step up the voltage output additionally for x-ray production. Two PT driven CW DC high voltage sources in a bi-polar configuration will double the maximum x-ray energy. The x-ray tube is under development with both field emitters and thermionic emitters being considered. Tests will be presented using a needle plane field emission cathode-anode configuration. Designs for a battery powered driver circuit for the PT and a CW driven compact xray source will be presented. $\mathrm{L}$ aboratory test results of these devices will also be presented.