VNIIA neutron generators for thermonuclear research

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• VNIIA neutron generators for thermonuclear
  research
•  

  Yevgeni P. Bogolubov, Valentin I.
Ryzhkov, Sergey V. Syromukov  
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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

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• All-Russian Research Institute of Automatics
  named after
• N.L. Dukhov (VNIIA) is one of the leading
  institutions governed by Federal Agency of Atomic
  Energy.
• One of the basic activity lines in the institute
  is the development and manufacture of neutron
  generators using sealed accelerating tubes.
• All produced by VNIIA generators may be divided
  into three types depending upon physical
  principles underlying their operation.
• 1. Generators using vacuum tubes
• 2. Generators using gas-filled tubes
• 3. Generators using "plasma focus" chambers

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Applications.
• 1. Hazard material control and detection (nuclear
  materials, explosives, toxic agents, drugs)
• 2. Oilgas field logging
• 3. Neutron radiography and tomography
• 4. Scientific research including solar system
  planet study
• 5. Oncological patient radiotherapy
• VNIIA is the only firm in the world manufacturing
  such variety of generator types having so wide
  spectrum of specifications and parameters. You
  may familiarize with products of VNIIA on
  website www.vniia.ru .

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• VNIIA serially produces generators having flux
  up to 1010 n/s. Urgent thermonuclear problem,
  radiotherapy, neutron radiography gave impetus
  for the development of neutron generators having
  1010 - 1011 n/s flux.
• The basic part of generator is sealed
  accelerating tube just the tube defines
  generator parameters. Typical circuit for
  gas-filled neutron tube is shown in Fig.1.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov
Figure 1. Gas-filled neutron tube circuit
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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Sealed neutron tube contains ion source,
  accelerating electrode system, and target
  combined in hermetic sealed housing. Tube volume
  includes getter containing bound deuterium and
  tritium. While operation at heating getter
  deuterium and tritium release in tube volume and
  are ionized in ion source. Produced ions are
  formed in beam and accelerated between tube
  electrodes. Accelerated ions bombard target
  saturated with deuterium and tritium, and
  neutrons produce as a result of thermonuclear
  reactions.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Gas-filled tubes use self-saturating neutron
  target. Such targets are saturated by deuterium
  and tritium while bombarding by ion beam within
  all tube operation time. This method allows
  appreciable increase of gas-filled tube life time
  in comparison with vacuum tubes. Tube has
  antidynatron electrode (suppressor) providing
  suppression of secondary electron current from
  target.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Sealed tubes in powerful neutron generators are
  normally counted for 150-250 kV at ion current
  3-5 mA. Such parameters provide neutron flux
  (0,5-1)x1011 n/s.
• Due to thermonuclear reactions 3H(d,n)4He or
  2H(d,n)3He used in generators for neutron
  production the generators may be successfully
  used for thermonuclear facilities neutron field
  simulation.
• Portable neutron generators with sealed
  accelerating tubes are the most perspective for
  the purposes. The peculiarity of such generators
  is complete safety when switched off, simple
  operation, small sizes, and operation at any
  position of neutron unit.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Simulation of thermonuclear facility neutron
  fields requires minimum distortion of neutron
  spectrum from tube target and distortion in
  neutron emission isotropy. For generator these
  requirements mean decrease of material quantity
  near target. This especially relates to materials
  with high coefficient of fast neutron scattering.
  For solving the task we used powering circuit for
  tube with grounded target in the developed
  generators for thermonuclear research. In such
  generators tube's ion source is under high
  potential inside hermetic housing of neutron unit
  filled with high-voltage dielectric
  neutron-emitting target is grounded and jutted
  out of housing.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov
Figure 2. Neutron unit of generator with
grounded target
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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Figure 2 shows neutron unit of generator with
  grounded target. Tube's target juts out neutron
  unit at about 50 mm. Target is heated by ion
  beam. Therefore target is cooled with water.
  Water film thickness near target is about 1 mm.
  High-voltage dielectric thermal compensator is
  positioned by neutron unit side opposite to tube.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• Some thermonuclear research using neutron
  generator should be performed within many tens
  hours. Generator and radiation detectors will be
  placed at rather distance from each other
  materials effectively absorbing neutron emission
  will be placed between them. This stipulates more
  high requirements to neutron output and life time
  of sealed tube. Generator should provide neutron
  flux of about 1011 n/s and life time of sealed
  tube should be at least 100 hours.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• In some studies neutron unit will be placed
  inside thermonuclear facilities. This requires
  minimizing dimensions of generator's emitting
  module neutron unit. It is necessary to provide
  transportability, possible displacement of
  neutron unit in thermonuclear facility volume.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• The next requirement is the possibility to
  obtain 2,5 MeV neutrons from the 2H(d,n)3He
  reaction. This requirement is realized by use of
  sealed tube filled with deuterium. D-D neutron
  output is about 100 times less than d-t neutron
  output because of difference in sections.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• VNIIA is currently developing the ING-14 and
  ING-24 neutron generators intended for simulation
  of thermonuclear facilities neutron field.
• The ING-14 generator has flux up to 5x1010 n/s.
  Its development is now at final stage. Both
  generators are intended for continuous operation
  within many hours without interruption. They have
  grounded targets, placed beyond neutron units
  that, as shown above, decreases distortion of
  neutron spectrum and radiation isotropy.
  Generators contain neutron unit, power supply
  unit, and cable kit.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• The ING-14 generator uses the GNT5-67 sealed tube
  shown in Fig.3. The tube has ion source with cold
  cathode and permanent magnet. Housing of the tube
  is metal-glass. Tube is mounted on ING-14 neutron
  unit flange so that source and metal-glass
  housing are inside unit and target juts out unit
  at about 5 cm. ING-14 neutron unit photo is
  presented in Fig.4.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov
Figure 3 

• GNT5-67 sealed neutron tube
• Neutron energy 14 MeV
• Neutron flux 5?1010n/s

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov
Figure 4.

• ING-14 neutron generator with GNT5-67 sealed tube
• Neutron energy 14 MeV
• Neutron flux
  5?1010n/s

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

• The ING-24 neutron generator is designed for
  1011 n/s the generator contains metal-ceramic
  tube GNT1-100 photo of this tube is presented in
  Fig.5. This tube is also mounted on ING-24
  neutron unit flange having rather large
  dimensions and appearance analogous to ING-14.
  Target of GNT1-100 tube juts out flange sizes at
  5 cm too.
• ING-14 and ING-24 specifications are presented
  in the Table 1.

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov
Figure 5. 

• The GNT1-100 neutron tube
• Neutron energy 14 MeV
• Neutron flux 1011n/s

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The All-Russian Research Institute of Automatics
named after N.L. Dukhov
Specifications of VNIIA neutron generators for
thermonuclear research
Parameter ING-14 ING-24
Neutron flux, n/s 0,5?1011 1?1011
Target Grounded Grounded
Tube life time, hours 300 200
Accelerating voltage, kV 150 270
Emission mode steady steady
Power supply 220 V, 50-60 Hz 220 V, 50-60 Hz
Operation mode continuous continuous
Neutron unit dimensions, mm ?240?620 ?280?700
Power supply dimensions, mm 465?430?155 465?430?300
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The All-Russian Research Institute of Automatics
named after N.L. Dukhov

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• Thus VNIIA has scientific-technical, design,
  technological and production base for development
  and manufacture of a wide class of neutron
  generators, in that number, generators for
  thermonuclear facilities neutron fields
  simulation.
• VNIIA is interested in developing
  sciencetechnical co-operation in both delivery
  of generators designed for thermonuclear research
  and joint development of generators and equipment
  on their base.
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