Applications of pyroelectric particle accelerators
01 Aug 2007-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms (Elsevier)-Vol. 261, Iss: 1, pp 110-113
TL;DR: In this article, a pyroelectric X-ray generator with a potential on the order of 100kV was presented, which is great enough to eject electrons from the crystal for the production of characteristic or bremsstrahlung X-rays, or to cause field ionization near a tip mounted to the crystal.
Abstract: The discovery of pyroelectric X-ray generation in 1992 by Brownridge has led to a recent surge of interest in the use of the pyroelectric effect as a means of producing useful radiation. By heating or cooling a pyroelectric crystal such as lithium tantalate (LiTaO3) in a vacuum, a potential on the order of 100 kV can be generated. This potential is great enough to eject electrons from the crystal for the production of characteristic or bremsstrahlung X-rays, or to cause field ionization near a tip mounted to the crystal. By using the combined fields of two polarized crystals, the acceleration potential can be doubled, with one crystal acting as a particle emitter and the other crystal serving as a target. Such a paired-crystal system was used to generate X-rays with energies of greater than 200 keV, and can be used to fluoresce the K shell of thorium (Z = 92). An alternative use of pyroelectric sources is the field ionization of a dilute gas. If the positively-charged crystal is used to ionize a deuterium gas, and the target crystal is coated with deuterated target, the deuterium ions can be accelerated into the target at high enough energy to cause D–D fusion. Results verifying the production of D–D fusion neutrons from a pyroelectric source will be presented. Future applications of pyroelectric accelerator technology, such as the use of the electron beam for materials testing, will also be discussed.
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TL;DR: In this paper, the potential and field strength of two-crystal pyroelectric accelerators were derived for a single-crystall system and for a two-carcinear system.
Abstract: Derivations for equations for calculating the potential and field strength in both single-crystal and two-crystal pyroelectric accelerators are presented. Such expressions for the single-crystal system are well established in the literature, but with cursory derivations. We provide a rigorous derivation of the single-crystal system and expand upon this physical understanding to derive expressions for the potential and field in a two-crystal system. The expressions are verified with finite element modeling and compared with experimental results. This allows for better understanding of pyroelectric accelerators.
30 citations
TL;DR: In this article, the applicability of polarized ferroelectric ceramics as a pyroelectric in a Pyroelectric accelerator has been shown by experiments, where the spectra of X-ray radiation of energy up to tens of keV, generated by accelerated electrons, have been measured on heating and cooling of the Ceramics in vacuum.
Abstract: The applicability of polarized ferroelectric ceramics as a pyroelectric in a pyroelectric accelerator is shown by experiments. The spectra of X-ray radiation of energy up to tens of keV, generated by accelerated electrons, have been measured on heating and cooling of the ceramics in vacuum. It is suggested that curved layers of polarized ferroelectric ceramics be used as elements of ceramic pyroelectric accelerators. Besides, nanotubes and nanowires manufactured from ferroelectric ceramics are proposed for the use in nanometer-scale ceramic pyroelectric nanoaccelerators for future applications in nanotechnologies.
21 citations
TL;DR: GODDESS as mentioned in this paper is a coupling of ORRUBA to the gamma-ray detector array Gammasphere, which has been developed in order to facilitate the high-resolution measurement of direct reactions in normal and inverse kinematics with stable and radioactive beams.
13 citations
11 Mar 2011-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the authors demonstrate a 14.1 MeV neutron source by which deuterons are accelerated into a tritiated target via the action of a pyroelectric crystal.
Abstract: We demonstrate a compact 14.1 MeV neutron source by which deuterons are accelerated into a tritiated target via the action of a pyroelectric crystal. At the ion currents we measured, the expected flux is about 3×10 5 neutrons per second. Although our measured flux was much less than expected, spectral analysis of the neutron signal unambiguously verified a 14.1 MeV neutron signal far above background. The experimental fusion rate is limited by surface flashover and the time development of a surface barrier on the target due to chemical contamination. Various improvements in the, management of flashover originating from triple points and stabilization of field ionization tips are discussed.
9 citations
TL;DR: In this paper, an experimental analysis in combination with simulation studies was reported to investigate possible sources of the self-focused electron beam effect in a pyroelectric crystal, where the surface of the crystal was divided into six separated parts and the rate of surface electric charge production was measured accordingly.
Abstract: Pyroelectric crystals are used to produce high energy self-focused electron beams. Here, an experimental analysis in combination with simulation studies will be reported to investigate possible sources of this effect. In the experiments, the surface of crystal was divided into six separated parts and the rate of surface electric charge production was measured accordingly. A non-steady and spatially non-uniform distribution of the surface charge generation was observed, in which it tends to a uniform distribution in the course of experiment. The obtained surface electric charges from the experiments were used to simulate the electric field and potential around the crystal by COMSOL Multiphysics. It was observed that emitted electrons from the crystal surface were focused, and the non-uniformity in spatial charge is responsible for this phenomenon.
8 citations
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Book•
01 Dec 1961
TL;DR: In this article, the theory of field emission and its application in adaption is discussed. But the application of field ionization to adsorption has not been discussed in detail.
Abstract: Contents: Theory of Field Emission. Field-Emission Microscopy and Related Topics. Field Ionization and Related Phenomena. Some Applications of Field Emission to Adsorption. Some Miscellaneous Applications of Field Emission.
1,283 citations
"Applications of pyroelectric partic..." refers methods in this paper
...We also demonstrate fusion neutron production using pyroelectric crystals, and suggest methods of improving the neutron yield....
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TL;DR: The electron emission from ferroelectrics (FEE) is an unconventional electron emission effect as discussed by the authors, which is a tunneling emission current which screens uncompensated polarization charges, generated by a deviation of macroscopic spontaneous polarization from its equilibrium state under pyroelectric effect, piezoelectric effect, or polarization switching.
Abstract: Electron emission from ferroelectrics (FEE) is an unconventional electron emission effect. Methods of FEE excitation are quite different compared to classic electron emission from solids. Two kinds of FEE have been observed, “weak” and “strong.” “Weak” electron emission (current density 10−12–10−7 A/cm2) occurs from polar surfaces of ferroelectric materials in the ferroelectric phase only. A source of the electric field for “weak” FEE excitation is an uncompensated charge, generated by a deviation of macroscopic spontaneous polarization from its equilibrium state under a pyroelectric effect, piezoelectric effect, or polarization switching. The FEE is a tunneling emission current which screens uncompensated polarization charges. It is shown that the FEE is an effective tool for direct domain imaging and studies of electronic properties of ferroelectrics. “Strong” FEE, which is 10–12 orders of magnitude higher than “weak” FEE, achieves 100 A/cm2 and is plasma-assisted electron emission. Two modes of the sur...
333 citations
TL;DR: It is reported that gently heating a pyroelectric crystal in a deuterated atmosphere can generate fusion under desktop conditions and it is anticipated that the system will find application as a simple palm-sized neutron generator.
Abstract: Many methods of reproducing nuclear fusion — the process that powers the Sun — at the table-top scale have been tried, but failed to convince. Remember ‘cold fusion’? More recently, fusion linked to sonoluminescence is still controversial. Now comes a claim from the labs of the University of California at Los Angeles of unequivocal evidence of nuclear fusion in a simple room-temperature experiment. They report that gently heating a pyroelectric crystal — material that becomes charged when heated — causes ionization of a surrounding deuterium gas. The ions bombard a deuterated solid target with such energy that a large neutron signal is detected, a hallmark of deuterium fusion. Though not a viable power source, ‘crystal fusion’ may find application as a generator of neutrons for imaging technology. While progress in fusion research continues with magnetic1 and inertial2 confinement, alternative approaches—such as Coulomb explosions of deuterium clusters3 and ultrafast laser–plasma interactions4—also provide insight into basic processes and technological applications. However, attempts to produce fusion in a room temperature solid-state setting, including ‘cold’ fusion5 and ‘bubble’ fusion6, have met with deep scepticism7. Here we report that gently heating a pyroelectric crystal in a deuterated atmosphere can generate fusion under desktop conditions. The electrostatic field of the crystal is used to generate and accelerate a deuteron beam (> 100 keV and >4 nA), which, upon striking a deuterated target, produces a neutron flux over 400 times the background level. The presence of neutrons from the reaction D + D → 3He (820 keV) + n (2.45 MeV) within the target is confirmed by pulse shape analysis and proton recoil spectroscopy. As further evidence for this fusion reaction, we use a novel time-of-flight technique to demonstrate the delayed coincidence between the outgoing α-particle and the neutron. Although the reported fusion is not useful in the power-producing sense, we anticipate that the system will find application as a simple palm-sized neutron generator.
221 citations
125 citations