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Neutron generators are neutron source
Neutron source

Neutron source is a general term referring to a variety devices that emit neutrons, irrespective of the mechanism used to produce the neutrons. Depending upon variables including the energy of the neutrons emitted by the source, the rate of neutrons emitted by the source, the size of the source, the cost of owning and maintaining the source,...
 devices which contain compact linear accelerators and that produce neutron
Neutron

The neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.Neutrons are usually found in atomic nucleus....
s by fusing isotopes of hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 together. The fusion
Nuclear fusion

In nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus....
 reactions take place in these devices by accelerating either deuterium
Deuterium

Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen ....
, tritium
Tritium

Tritium is a radioactive isotope of hydrogen. The atomic nucleus of tritium contains one proton and two neutrons, whereas the nucleus of Hydrogen atom contains one proton and no neutrons....
, or a mixture of these two isotopes into a metal hydride target which also contains either deuterium, tritium or a mixture. Fusion of deuterium atoms (D + D) results in the formation of a He-3 ion and a neutron with a kinetic energy of approximately 2.5 MeV
MEV

MeV and meV are Multiple of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:...
.






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Neutron generators are neutron source
Neutron source

Neutron source is a general term referring to a variety devices that emit neutrons, irrespective of the mechanism used to produce the neutrons. Depending upon variables including the energy of the neutrons emitted by the source, the rate of neutrons emitted by the source, the size of the source, the cost of owning and maintaining the source,...
 devices which contain compact linear accelerators and that produce neutron
Neutron

The neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.Neutrons are usually found in atomic nucleus....
s by fusing isotopes of hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 together. The fusion
Nuclear fusion

In nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus....
 reactions take place in these devices by accelerating either deuterium
Deuterium

Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen ....
, tritium
Tritium

Tritium is a radioactive isotope of hydrogen. The atomic nucleus of tritium contains one proton and two neutrons, whereas the nucleus of Hydrogen atom contains one proton and no neutrons....
, or a mixture of these two isotopes into a metal hydride target which also contains either deuterium, tritium or a mixture. Fusion of deuterium atoms (D + D) results in the formation of a He-3 ion and a neutron with a kinetic energy of approximately 2.5 MeV
MEV

MeV and meV are Multiple of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:...
. Fusion of a deuterium and a tritium atom (D + T) results in the formation of a He-4 ion and a neutron with a kinetic energy of approximately 14.1 MeV.

Thousands of such small, relatively inexpensive systems have been built over the past five decades.

Neutron Generator


Sealed Neutron Tubes


Ion Sources


Spark Gap


Cold Cathode (Penning)


Hot Cathode


Microwave


Electron Cyclotron Resonance (ECR)


Radio Frequency (RF)


Field Ionization and Field Desoprtion


Targets


High Voltage Power Supplies


One particularly interesting approach for generating the high voltage fields needed to accelerate ions in a neutron tube is to use a pyroelectric crystal. In April 2005 researchers at UCLA demonstrated the use of a thermally cycled pyroelectric crystal to generate high electric fields in a neutron generator application. In February 2006 researchers at Rensselaer Polytechnic Institute
Rensselaer Polytechnic Institute

Rensselaer Polytechnic Institute, or RPI, is a Private university research university located in Troy, New York, New York, United States. RPI was founded in 1824 by Stephen Van Rensselaer III for the "application of science to the common purposes of life", and is the oldest technological university in the English-speaking world....
 demonstrated the use of two oppositely poled crystals for this application. Using these low-tech power supplies it is possible to generate a sufficiently high electric field
Electric field

In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field ....
 gradient across an accelerating gap to accelerate deuterium ions into a deuterated target to produce the D + D fusion reaction. These devices are similar in their operating principle to conventional sealed-tube neutron generators which typically use Cockcroft-Walton
Cockcroft-Walton generator

The Cockcroft-Walton generator, or multiplier, was named after the two men who in 1932 used this circuit design to power their particle accelerator, performing the first artificial nuclear disintegration in history....
 type high voltage power supplies. The novelty of this approach is in the simplicity of the high voltage source. Unfortunately, the relatively low accelerating current that pyroelectric crystals can generate, together with the modest pulsing frequencies that can be achieved (a few cycles per minute) limits their near-term application in comparison with today's commercial products (see below). Also see pyroelectric fusion
Pyroelectric fusion

Pyroelectric fusion refers to the technique of using pyroelectricity crystals to generate high strength electrostatic fields to accelerate deuterium ions into a metal hydride target also containing deuterium with sufficient kinetic energy to cause these ions to undergo nuclear fusion....
.

High Voltage Insulation


Other Neutron Generator Technologies


In addition to the conventional neutron generator design described above several other approaches exist to use electrical systems for producing neutrons.

Inertial Electrostatic Confinement/Fusor

Another type of innovative neutron generator is the inertial electrostatic confinement
Inertial electrostatic confinement

Inertial electrostatic confinement is a concept for retaining a Plasma using an electrostatic field. The field accelerates charged particles radially inward, usually in a spherical but sometimes in a cylindrical geometry....
 fusion device. This neutron generator differs from the conventional ion beam onto solid target types because it avoids using a solid target which will be sputter eroded causing metalization of insulating surfaces. Depletion of the reactant gas within the solid target is also avoided. Far greater operational lifetime is achieved. Originally called a fusor, it was invented by Philo Farnsworth
Philo Farnsworth

Philo Taylor Farnsworth was an United States inventor. He is best known for inventing the first completely electronic television. In particular, he was the first to make a working electronic image pickup device , and the first to demonstrate an all-electronic television system to the public....
, the inventor of electronic television
Television

Television is a widely used telecommunication mass-media for transmitting and receiving moving , either monochrome or color, usually accompanied by sound....
. This type of neutron generator is manufactured by NSD-Fusion. (Note: An extensive discussion of this technology is available in the fusor
Fusor

The Farnsworth?Hirsch Fusor, or simply fusor, is an apparatus Invention by Philo T. Farnsworth to create nuclear fusion. It has also been developed in various incarnations by researchers including Elmore, Tuck, and Watson, and more lately by George Miley and Robert W....
 wiki.)


Dense Plasma Focus


Organizations that manufacture neutron generators

  • , Adelphi Technology (USA)
  • , Baker Hughes (USA)
  • , EADS SODERN (France)
  • , Halliburton (USA)
  • , Hotwell GmbH (Austria) [Using neutron tubes from VNIIA]
  • , Lawrence Berkeley National Laboratory (USA)
  • , NSD-Fusion (Germany)
  • , Sandia National Laboratories (USA)
  • , Schlumberger (USA)
  • , Thermo Fisher Scientific (USA)
  • , VNIIA All Russia Research Institute of Automatics (Russia)


See also


  • Fast neutron
  • Nuclear fission
    Nuclear fission

    In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the atomic nucleus of an atom splits into smaller parts, often producing free neutrons and lighter atomic nucleus, which may eventually produce photons ....
  • Nuclear fusion
    Nuclear fusion

    In nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus....
  • Neutron source
    Neutron source

    Neutron source is a general term referring to a variety devices that emit neutrons, irrespective of the mechanism used to produce the neutrons. Depending upon variables including the energy of the neutrons emitted by the source, the rate of neutrons emitted by the source, the size of the source, the cost of owning and maintaining the source,...
  • Neutron moderator
    Neutron moderator

    In nuclear engineering, a neutron moderator is a medium which reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235....
  • Radioactive decay
    Radioactive decay

    Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide....
  • Radioactivity
  • Slow neutron


External links

  • , AIP, The Industrial Physicist