High-energy x-ray production with pyroelectric crystals

Abstract

The invention of pyroelectric x-ray generator technology has enabled researchers to develop ultraportable, low-power x-ray sources for use in imaging, materials analysis, and other applications. For many applications, the usefulness of an x-ray source is determined by its yield and endpoint energy. In x-ray fluorescence, for example, high-energy sources enable the excitation of the K-shell x-ray peaks for high-Z materials as well as the lower-energy L-shell peaks, allowing more positive sample identification. This report shows how a paired-crystal pyroelectric source can be used to approximately double the endpoint x-ray energy, in addition to doubling the x-ray yield, versus a single-crystal source. As an example of the advantage of a paired-crystal system, we present a spectrum showing the fluorescence of the K shell of thorium using a pyroelectric source, as well as a spectrum showing the fluorescence of the K shell of lead. Also shown is an x-ray spectrum with an endpoint energy of 215 keV.

Ionization mechanism of the ambient pressure pyroelectric ion source (APPIS) and its applications to chemical nerve agent detection

“…A mechanism of ionization involving a form of atmospheric pressure chemical ionization is proposed, whereby molecules that are detected as protonated species have undergone reaction with reactant ions present in humid air of the form ϩ H(H 2 O) n or Ϫ OH(H 2 O) n . Previous work by others on pyroelectric materials has revealed the production of ions and electrons from pyroelectric crystals [7][8][9][10][11][12][13][14][15] as well as field ionization of deuterium gas to form D ϩ , which is used in pyroelectric fusion experiments [16,17]. None of these studies involve ionization at ambient pressure as the chief mode of ionization.…”

A Novel Compact Pyroelectric X-Ray and Neutron Source

“…Therefore, it is possible that the endpoint energy would have appeared higher with improved detection efficiency at high energy. Nevertheless, the plot shown in Figure 4.15 is the highest-energy spectrum ever published from a pyroelectric x-ray source, and serves as a highlight to the advantages of paired-crystal technology 50 . …”

“…Improvements were later made to his design by utilizing a paired-crystal geometry in which the superposition of two pyroelectric fields allowed the doubling of the acceleration potential, x-ray energy, and x-ray yield 50 .…”

“…At that point, the ability of pyroelectric crystals to produce a high acceleration potential 50 had been verified, and ion and electron spectroscopy experiments had been performed 34 . However, the ability of the crystal to ionize a fill gas was of crucial importance to the prospect of pyroelectric fusion.…”

Enhancement of pyroelectric current induced by radiant heat

“…Pyroelectric crystals, especially LiTaO 3 , are intensively studied to accelerate ions [2] and to produce x-rays [3,4] and neutrons [5]. The typical crystal dimension used in many experiments is a radii 10-mm to 20-mm and length of 10-mm to 20-mm [6,7].…”