Pyroelectric fusion
Encyclopedia
Pyroelectric fusion refers to the technique of using pyroelectric
crystal
s to generate high strength electrostatic fields to accelerate deuterium
ion
s (tritium
might also be used someday) into a metal hydride target also containing deuterium (or tritium) with sufficient kinetic energy to cause these ions to undergo nuclear fusion
. It was reported in April 2005 by a team at UCLA
. The scientists used a pyroelectric
crystal heated from −34 to 7 °C (−29 to 45 °F), combined with a tungsten
needle to produce an electric field
of about 25 gigavolts per meter to ionize and accelerate deuterium
nuclei into an erbium deuteride target. Though the energy of the deuterium ions generated by the crystal has not been directly measured, the authors used 100 keV (a temperature of about 109 K
) as an estimate in their modeling. At these energy levels, two deuterium nuclei can fuse together to produce a helium-3
nucleus, a 2.45 MeV neutron
and bremsstrahlung
. Although it makes a useful neutron generator, the apparatus is not intended for power generation since it requires far more energy than it produces.
and Walton
in 1932 (see Cockroft-Walton generator
). Indeed, the process is used today in thousands of miniaturized versions of their original accelerator, in the form of small sealed tube neutron generator
s, in the petroleum exploration industry.
The process of pyroelectricity has been known from ancient times.[1] The first use of a pyroelectric field to accelerate deuterons was in 1997 in an experiment conducted by Drs. V.D. Dougar Jabon, G.V. Fedorovich, and N.V. Samsonenko.[2] This group was the first to utilize a lithium tantalate
pyroelectric crystal in fusion experiments.
The novel idea with the pyroelectric approach to fusion is in its application of the pyroelectric effect to generate the accelerating electric fields. This is done by heating the crystal from −30°C to +45°C over a period of a few minutes.
probe attached to a pyroelectric crystal in order to increase the electric field strength.[3] Brian Naranjo, a graduate student working on his Ph.D. degree under Putterman, conducted the experiment demonstrating the use of a pyroelectric power source for producing fusion on a laboratory bench top device.[4] The device used a lithium tantalate
pyroelectric crystal to ionize deuterium atoms and to accelerate the deuterons towards a stationary erbium
dideuteride (D
2) target. Around 1000 fusion reactions per second took place, each resulting in the production of an 820 keV
helium-3
nucleus
and a 2.45 MeV
neutron. The team anticipates applications of the device as a neutron generator
or possibly in microthrusters for space propulsion.
A team at Rensselaer Polytechnic Institute
, led by Dr. Yaron Danon and his graduate student Jeffrey Geuther, improved upon the UCLA experiments using a device with two pyroelectric crystals and capable of operating at non-cryogenic temperatures.[5][6]
Nuclear D-D fusion driven by pyroelectric crystals was proposed by Naranjo and Putterman in 2002.[7] It was also discussed by Brownridge and Shafroth in 2004.[8] The possibility of using pyroelectric crystals in a neutron production device (by D-D fusion) was proposed in a conference paper by Geuther and Danon in 2004[9] and later in a publication discussing electron and ion acceleration by pyroelectric crystals.[10] None of these later authors had prior knowledge of the earlier 1997 experimental work conducted by Dougar Jabon, Fedorovich, and Samsonenko.[2] The key ingredient of using a tungsten needle to produce sufficient ion beam current for use with a pyroelectric crystal power supply was first demonstrated in the 2005 Nature paper, although in a broader context tungsten emitter tips have been used as ion sources in other applications for many years. In 2010 it was found that tungsten emitter tips are not necessary to increase the acceleration potential of pyroelectric crystals; the acceleration potential can allow positive ions to reach kinetic energies between 300 and 310 keV.[11]
Pyroelectric fusion has been hyped in the news media,[12] which has overlooked the earlier experimental work of Dougar Jabon, Fedorovich and Samsonenk.[2] Pyroelectric fusion is not related to the earlier claims of fusion reactions, having been observed during sonoluminescence
(bubble fusion
) experiments conducted under the direction of Dr. Rusi P. Taleyarkhan of Purdue University
.[13] In fact, Naranjo of the UCLA team has been one of the main critics of these earlier prospective fusion claims from Taleyarkhan.[14]
The first successful results with pyroelectric fusion using a tritiated target was reported in 2010.[15] The UCLA team of Putterman and Naranjo worked with Dr. T. Venhaus of Los Alamos National Laboratory
to measure a 14.1 MeV neutron signal far above background. This was a natural extension of the earlier work with deuterated targets.
Pyroelectricity
Pyroelectricity is the ability of certain materials to generate a temporary voltage when they are heated or cooled. The change in temperature modifies the positions of the atoms slightly within the crystal structure, such that the polarization of the material changes. This polarization change...
crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s to generate high strength electrostatic fields to accelerate deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s (tritium
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
might also be used someday) into a metal hydride target also containing deuterium (or tritium) with sufficient kinetic energy to cause these ions to undergo nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
. It was reported in April 2005 by a team at UCLA
University of California, Los Angeles
The University of California, Los Angeles is a public research university located in the Westwood neighborhood of Los Angeles, California, USA. It was founded in 1919 as the "Southern Branch" of the University of California and is the second oldest of the ten campuses...
. The scientists used a pyroelectric
Pyroelectricity
Pyroelectricity is the ability of certain materials to generate a temporary voltage when they are heated or cooled. The change in temperature modifies the positions of the atoms slightly within the crystal structure, such that the polarization of the material changes. This polarization change...
crystal heated from −34 to 7 °C (−29 to 45 °F), combined with a tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
needle to produce an electric field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
of about 25 gigavolts per meter to ionize and accelerate deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
nuclei into an erbium deuteride target. Though the energy of the deuterium ions generated by the crystal has not been directly measured, the authors used 100 keV (a temperature of about 109 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
) as an estimate in their modeling. At these energy levels, two deuterium nuclei can fuse together to produce a helium-3
Helium-3
Helium-3 is a light, non-radioactive isotope of helium with two protons and one neutron. It is rare on Earth, and is sought for use in nuclear fusion research...
nucleus, a 2.45 MeV neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
and bremsstrahlung
Bremsstrahlung
Bremsstrahlung is electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus. The moving particle loses kinetic energy, which is converted into a photon because energy is conserved. The term is...
. Although it makes a useful neutron generator, the apparatus is not intended for power generation since it requires far more energy than it produces.
History
The process of light ion acceleration using electrostatic fields and deuterium ions to produce fusion in solid deuterated targets was first demonstrated by CockcroftJohn Cockcroft
Sir John Douglas Cockcroft OM KCB CBE FRS was a British physicist. He shared the Nobel Prize in Physics for splitting the atomic nucleus with Ernest Walton, and was instrumental in the development of nuclear power....
and Walton
Ernest Walton
Ernest Thomas Sinton Walton was an Irish physicist and Nobel laureate for his work with John Cockcroft with "atom-smashing" experiments done at Cambridge University in the early 1930s, and so became the first person in history to artificially split the atom, thus ushering the nuclear age...
in 1932 (see Cockroft-Walton generator
Cockcroft-Walton generator
The Cockcroft–Walton generator, or multiplier, is an electric circuit which generates a high DC voltage from a low voltage AC or pulsing DC input...
). Indeed, the process is used today in thousands of miniaturized versions of their original accelerator, in the form of small sealed tube neutron generator
Neutron generator
Neutron generators are neutron source devices which contain compact linear accelerators and that produce neutrons by fusing isotopes of hydrogen together. The fusion reactions take place in these devices by accelerating either deuterium, tritium, or a mixture of these two isotopes into a metal...
s, in the petroleum exploration industry.
The process of pyroelectricity has been known from ancient times.[1] The first use of a pyroelectric field to accelerate deuterons was in 1997 in an experiment conducted by Drs. V.D. Dougar Jabon, G.V. Fedorovich, and N.V. Samsonenko.[2] This group was the first to utilize a lithium tantalate
Lithium tantalate
Lithium tantalate , is a crystalline solid which possesses unique optical, piezoelectric and pyroelectric properties which make it valuable for nonlinear optics, passive infrared sensors such as motion detectors, terahertz generation and detection, surface acoustic wave applications, cell phones...
pyroelectric crystal in fusion experiments.
The novel idea with the pyroelectric approach to fusion is in its application of the pyroelectric effect to generate the accelerating electric fields. This is done by heating the crystal from −30°C to +45°C over a period of a few minutes.
Results since 2005
In April 2005 a UCLA team headed by the Distinguished Professor of Chemistry and Fellow of the Royal Society James K. Gimzewski and Professor of Physics Seth Putterman utilized a tungstenTungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
probe attached to a pyroelectric crystal in order to increase the electric field strength.[3] Brian Naranjo, a graduate student working on his Ph.D. degree under Putterman, conducted the experiment demonstrating the use of a pyroelectric power source for producing fusion on a laboratory bench top device.[4] The device used a lithium tantalate
Lithium tantalate
Lithium tantalate , is a crystalline solid which possesses unique optical, piezoelectric and pyroelectric properties which make it valuable for nonlinear optics, passive infrared sensors such as motion detectors, terahertz generation and detection, surface acoustic wave applications, cell phones...
pyroelectric crystal to ionize deuterium atoms and to accelerate the deuterons towards a stationary erbium
Erbium
Erbium is a chemical element in the lanthanide series, with the symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements on Earth...
dideuteride (D
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
2) target. Around 1000 fusion reactions per second took place, each resulting in the production of an 820 keV
Kev
Kev can refer to:*Kev Hawkins, a fictional character.*Kevin, a given name occasionally shortened to "Kev".*Kiloelectronvolt, a unit of energy who symbol is "KeV".* Krefelder Eislauf-VereinKEV can refer to:...
helium-3
Helium-3
Helium-3 is a light, non-radioactive isotope of helium with two protons and one neutron. It is rare on Earth, and is sought for use in nuclear fusion research...
nucleus
Atomic nucleus
The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The...
and a 2.45 MeV
MEV
MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...
neutron. The team anticipates applications of the device as a neutron generator
Neutron generator
Neutron generators are neutron source devices which contain compact linear accelerators and that produce neutrons by fusing isotopes of hydrogen together. The fusion reactions take place in these devices by accelerating either deuterium, tritium, or a mixture of these two isotopes into a metal...
or possibly in microthrusters for space propulsion.
A team at Rensselaer Polytechnic Institute
Rensselaer Polytechnic Institute
Stephen Van Rensselaer established the Rensselaer School on November 5, 1824 with a letter to the Rev. Dr. Samuel Blatchford, in which van Rensselaer asked Blatchford to serve as the first president. Within the letter he set down several orders of business. He appointed Amos Eaton as the school's...
, led by Dr. Yaron Danon and his graduate student Jeffrey Geuther, improved upon the UCLA experiments using a device with two pyroelectric crystals and capable of operating at non-cryogenic temperatures.[5][6]
Nuclear D-D fusion driven by pyroelectric crystals was proposed by Naranjo and Putterman in 2002.[7] It was also discussed by Brownridge and Shafroth in 2004.[8] The possibility of using pyroelectric crystals in a neutron production device (by D-D fusion) was proposed in a conference paper by Geuther and Danon in 2004[9] and later in a publication discussing electron and ion acceleration by pyroelectric crystals.[10] None of these later authors had prior knowledge of the earlier 1997 experimental work conducted by Dougar Jabon, Fedorovich, and Samsonenko.[2] The key ingredient of using a tungsten needle to produce sufficient ion beam current for use with a pyroelectric crystal power supply was first demonstrated in the 2005 Nature paper, although in a broader context tungsten emitter tips have been used as ion sources in other applications for many years. In 2010 it was found that tungsten emitter tips are not necessary to increase the acceleration potential of pyroelectric crystals; the acceleration potential can allow positive ions to reach kinetic energies between 300 and 310 keV.[11]
Pyroelectric fusion has been hyped in the news media,[12] which has overlooked the earlier experimental work of Dougar Jabon, Fedorovich and Samsonenk.[2] Pyroelectric fusion is not related to the earlier claims of fusion reactions, having been observed during sonoluminescence
Sonoluminescence
Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound.-History:The effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. H. Frenzel and H. Schultes put an ultrasound transducer in a tank of...
(bubble fusion
Bubble fusion
Bubble fusion, also known as sonofusion, is the non-technical name for a nuclear fusion reaction hypothesized to occur during a high-pressure version of sonoluminescence, an extreme form of acoustic cavitation...
) experiments conducted under the direction of Dr. Rusi P. Taleyarkhan of Purdue University
Purdue University
Purdue University, located in West Lafayette, Indiana, U.S., is the flagship university of the six-campus Purdue University system. Purdue was founded on May 6, 1869, as a land-grant university when the Indiana General Assembly, taking advantage of the Morrill Act, accepted a donation of land and...
.[13] In fact, Naranjo of the UCLA team has been one of the main critics of these earlier prospective fusion claims from Taleyarkhan.[14]
The first successful results with pyroelectric fusion using a tritiated target was reported in 2010.[15] The UCLA team of Putterman and Naranjo worked with Dr. T. Venhaus of Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
to measure a 14.1 MeV neutron signal far above background. This was a natural extension of the earlier work with deuterated targets.
See also
- Neutron sourceNeutron sourceA Neutron source is a device that emits neutrons. There is a wide variety of different sources, ranging from hand-held radioactive sources to neutron research facilities operating research reactors and spallation sources...
s - Neutron generatorNeutron generatorNeutron generators are neutron source devices which contain compact linear accelerators and that produce neutrons by fusing isotopes of hydrogen together. The fusion reactions take place in these devices by accelerating either deuterium, tritium, or a mixture of these two isotopes into a metal...
- PyroelectricityPyroelectricityPyroelectricity is the ability of certain materials to generate a temporary voltage when they are heated or cooled. The change in temperature modifies the positions of the atoms slightly within the crystal structure, such that the polarization of the material changes. This polarization change...
- Pyroelectric crystalPyroelectric crystalPyroelectric crystals are crystals that generate electricity when heated. It is similar to piezoelectricity.-Crystal symmetry:Crystal structures can be divided into 32 classes, or point groups, according to the number of rotational axes and reflection planes they exhibit that leave the crystal...
External links
- "UCLA crystal fusion website"
- "Mostly cold fusion"
- "Physics News Update 729"
- "Coming in out of the cold: nuclear fusion, for real | csmonitor.com"
- "Nuclear fusion on the desktop...really! - Science - MSNBC.com - an article to hype the great UCLA team! Again, see reference 2 (above) for who should first get the credit"
- "Supplementary methods for "Observation of nuclear fusion driven by a pyroelectric crystal" is found in reference 3 (above)"