High energy and high intensity electron and X-ray beams by pyroelectric effect

Abstract

The production of x-rays has been a useful technique in many areas of science, medicine and various industries for over 100 years. Over this time various new methods of generating x-rays have been produced, allowing improved performance in existing applications as well as the application of x-rays in new areas. In this project a novel method of electron beam production, with the potential for development into a novel method of x-ray production is presented, using both pyroelectric and ferroelectric materials. The pyroelectric e ect, i.e. the generation of a charge due to a change in temperature is an e ect exhibited by certain dielectric materials. This e ect has previously been used in x-ray generation, and has been su ently successful that a commercial device has been produced: the Amptek Cool-X. While the Cool-X has only a limited electron / x-ray energy, high energy applications of this technology are present in the literature. This shows that these materials are capable of high voltages. However, the technique is not suitable for high beam intensity applications, limiting the potential use of pyroelectric x-ray devices. Ferroelectric electron emission is a technique used to generate elec- tron beams by applying a high voltage pulse to a specially prepared cathode. This technique has shown great potential for very high intensity pulsed electron beam generation. The major drawback of this technique is that while the cathodes are relitivly cheap and easy to produce, the other required equipment (such as high vacuum systems and high voltage pulse generators) is typically large and expensive. This project combines these two technologies to create an electron beam generation system that exhibits many of the ad- vantages of each technology, while minimizing the drawbacks. The result is a device using pyroelectric materials as voltage generatingelements for electron acceleration and high voltage pulse production, while a ferroelectric cathode is employed as the electron generating element. This system has been shown to, depending on con guation, be capable of accelerating voltages above 5 kV, and generating total collected charges of more than -40 nC per pulse.