Neutron Generators

The Neutron Generators with suitable examples and sketches are discuss here advanced. It is needed to read as engineer student.

Types of neutron sources:

1. Isotopic (ampoule) sources.
2. The accelerator as a source of neutrons.
3. Neutron generators.
4. Reactors:
5. industrial research: – continuous; – impulse.
6. Plasma traps.

Neutron Generators

The neutron generator uses the same nuclear physics reactions as the accelerator to produce neutrons. The most widely used are generators in the 3T (d, n) 4He reactions; less often, generators in the 2D (d, n) 3He reactions are used. The cross section maxima of these reactions are observed at low energies (Fig. 2.4), which means that it is possible to use not large accelerators, but so-called cascade generators. As a rule, deuterons are accelerated. The generator consists of an ion source; accelerator tube; converter targets from tritium or deuterium; power supplies of an ion source.

The target converters of neutron generators that allow obtaining high-intensity neutron fluxes are usually solid-state and are thin layers (up to several tens of micrometers) of titanium, scandium, or zinc deposited on a copper substrate (Fig. 2.5). These metals are capable of forming the so-called metallic hydrides. So titanium or scandium hydrides are capable of holding up to two hydrogen isotope atoms per metal atom. This property of metal hydrides makes it possible to use them as accumulators of hydrogen isotopes and, in particular, to make target converters from them. The energy lost by a beam of charged particles in a target can reach large values ​​(up to tens of kilowatts per square centimeter). This requires efficient cooling. Water cooling is commonly used. In addition, the target often represents a rapidly rotating

A section of a neutron generator target: 1) a titanium layer, 2) cooling channels, 3) a copper substrate

disk. Thus, the effective area over which the beam enters increases. In fig. 2.6 shows a simplified diagram of a neutron generator. At low deuteron energies, alpha particles from the 3T (d, n) 4He reaction fly out of the converter target at angles close to 180 ° relative to the direction of neutron emission. If alpha particles are detected, then the corresponding neutrons turn out to be “tagged”. The energies and directions of departure from a neutron converter target through kinematic relations are uniquely related to the energies and angles of departure of alpha particles. Thus, electron collimation of the neutron beam can be realized. The moment of neutron emission from the target is also recorded by detecting the accompanying alpha particles, which can be used in the time-of-flight technique.

On neutron generators using the 3T (d, n) 4He reaction, it is possible to obtain neutron fluxes of up to ~ 1014 neutrons / s at a solid angle of 4π. In “standard” neutron generators they are noticeably smaller (~ 1010 neutrons / s). Neutron generators are made on the basis of vacuum and gas-filled neutron tubes and chambers with a plasma focus (Fig. 2.7). Neutron generators can be very small-sized, for example, for working in wells. In fig. 2.8 priv

The appearance of several neutron generators developed by FSUE VNIIA for radiation analysis equipment was denied.

Neutron tubes and plasma focus chambers manufactured by FSUE VNIIA

The Neutron Generators with suitable examples and sketches are discuss here advanced. It is needed to read as engineer student.

Reference Neutron Generators

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