Accelerating neutron tube

FIELD: electricity.

SUBSTANCE: device contains a sealed case with a cylindrical cathode and a target applied on its surface, which are placed inside the case coaxially, and an anode covered symmetrically by the cathode. At that the anode in the claimed device is made as two butt-placed symmetrical rods with diameter a, at which butt ends there are caps made of deuterated metal and shifted in regard to each other per distance d along the tube axis of symmetry, the cathode diameter b meets inequality 0.2<a/b<0.3 while the anode diameter meets inequality 0.2<a/d<1.0.

EFFECT: improving energetic efficiency of neutron generation.

1 dwg

The invention relates to the field of accelerator technology, in particular to the vacuum devices for generating neutrons by nuclear interaction of pulsed flow of accelerated nuclei of hydrogen with solid targets, containing the heavy isotopes of hydrogen.

Known vacuum neutron tubes (EIT) [1, 2], in which the acceleration of deuterons to a solid target containing tritium in a nuclear fusion reaction to form a stream of fast neutrons.

In these devices the acceleration of deuterons is along the symmetry axis of the EIT, which limits Persians the diode system, and hence the neutron flux emitted by the target. Therefore, such devices are difficult to use in transportable equipment neutron elemental analysis, as well as for the detection and identification of concealed dangerous items and substances.

Also known vacuum neutron tube, described in [3]. In this tube the acceleration of deuterons is carried out in the radial direction, perpendicular to the axis of symmetry, which allows to significantly increase Persians diode system. This technical solution can be selected as a prototype, as the most similar in essential characteristics to declare.

This device comprises a sealed enclosure, inside of which are coaxially arranged qi is andrijeski the cathode with the target printed on its inner surface and containing the heavy isotopes of hydrogen, the anode symmetrically covered by the cathode and cylindrical mesh electrode displacement, located in front of the target and intended to suppress the emission of electrons from the target.

The disadvantage of this device is its low energy efficiency when working BHT-mode generation of a large neutron flux (>10⁹n/s in the full solid angle). When implementing these modes electrode suppress the emission of electrons from the target itself becomes a source of electrons in the field, explosive and autoelectronic emission.

The technical result of the proposed device is to increase the energy efficiency of generation of neutrons.

This result is achieved that the device containing a sealed enclosure, inside of which are coaxially arranged cylindrical cathode target containing the heavy isotopes of hydrogen deposited on its inner surface, and an anode symmetrically covered by the cathode, the anode is made in the form of two opposing symmetrical rods in diameter and, at the ends of which are placed the nozzle of the metal saturated with deuterium, are displaced relative to each other by a distance d along the axis of symmetry of the tube, the diameter of the cathode b must satisfy NERV is NSTU

$$0.2<\frac{a}{b}<\mathrm{0.3,}(1)$$

and the diameter of the anode inequality

$$0.2<\frac{a}{d}<1.0(2)$$

Schematic section of the device represented in figure 1. It contains the following items: cathode 1, anode rods 2, the insulator 3, deuterated nozzles 4, target 5.

The device operates as follows. The amount of anode rods serves a voltage pulse with an amplitude of 2 to 10 kV and up to 10 µs. One of the terminals is grounded. As a result, the gap between the nozzles, saturated with deuterium, is formed by a vacuum arc. Its electrode spots emit a jet of plasma, containing deuterons. Synchronously with the pulse at the cathode is supplied a negative accelerating pulse amplitude (100÷500) kV. Due to the resulting radial electric field is the acceleration of deuterons to the cylindrical target, containing the heavy isotopes of hydrogen. In the result of nuclear reactions T(d, n)⁴He or D(d, n)³He targets formed the fast neutron flux.

To work effectively condition the device must meet the requirements of the magnetic isolation of the accelerating gap, when the electrons cannot reach the anode. In this EIT source azimuthal magnetic field is the current flowing in the anode in the arc discharge. Estimates show that the condition for magnetic isolation is the fulfillment of the inequality:

$$I\ge \frac{I_A}{2\ln \frac{b}{a}}{\left[\frac{eU}{m{c}^2}\left(1+\frac{eU}{2m{c}^2}\right)\right]}^{1/2}$$,

where$$I_A=\frac{4\pi {\epsilon }_{0}m{c}^3}{e}\cong 17KA$$

- current alfvén, m, e are mass and charge of the electron, U is the amplitude of the accelerating pulse, c is the speed of light.

For optimal from the point of view of the emitted neutron flux, the geometric dimensions of the diode held a special computer experiment. The experiment was limited to the joint solution of the equations of dynamics and self-consistent Poisson's equation by the method of "large particles" [4].

As a result, the ATA busting the geometric dimensions of the diode were set ratio (1), where it is possible to achieve the maximum value of the neutron flux emitted by the diode in the full solid angle.

The relation (2) is determined through the above-mentioned range of possible variations of the voltage between the anode rods and conditions of vacuum breakdown.

Thanks to magnetic isolation is the suppression of the electronic conductivity of the accelerating gap. Due to this increase in energy efficiency of generation of neutrons and increase the neutron yield by increasing perveance diode system.

Development and implementation of the proposed device should improve performance studies of rocks containing productive hydrocarbons, uranium and precious metals by the method of neutron elemental analysis, as well as work related to the search and identification of hidden dangerous goods neutron methods.

Sources of information

1. Bespalov J.F. ñ, Vasin B.C., Ovsyannikov D.B Compact pulsed neutron tube HT-16, HT-19. Sat. Downhole neutron generators, VNIIG, lecture notes, M, 1973, s-87.

2. Bessarabian YG, Betuli A.A., Bobylev V.T. and other Pulsed neutron generators vacuum neutron tubes. Sat. materials of International scientific-technical conference "Portable neutron generators and technologies on their basis is, M, VNIIA them. D. spirit, 2005, p.72.

3. Bespalov J.F. ñ, Mintz AS, Pleshakova R.P., Shikanov AU Pulsed neutron generator. As the USSR №457406, 1972.

4. Radikov V.I. Calculation of electromagnetic fields in the structures of complex geometry. Problems of atomic science and technology. Ser. Nuclear physics research, 1990, V. 10(18). P.50-53.

Accelerator neutron tube containing a sealed enclosure, inside of which are coaxially arranged cylindrical cathode with a target printed on its inner surface, and an anode symmetrically covered by the cathode, characterized in that, to increase the energy efficiency of generation of neutrons, the anode is made in the form of two opposing symmetrical rods in diameter and, at the ends of which are placed the nozzle of the metal saturated with deuterium, are displaced relative to each other by a distance d along the axis of symmetry of the tube, the diameter of the cathode b must satisfy the inequality
$$0.2<\frac{a}{b}<0.3$$,
and the diameter of the anode inequality
$$0.2<\frac{a}{d}<1.0$$.