RU1820945C - Neutron pulse oscillator - Google Patents

Abstract

Usage: turf geophysics and other areas of neutron technology. SUMMARY OF THE INVENTION: the generator comprises a pulsed discharge transformer with a filler and a forming line electrode connected to an additional electrode, a composite cathode consisting of a cathode electrode and a truncated cone cathode located near the passage hole of the end anode in the vacuum chamber. The areas of location of the pulsed discharge and the anode are hermetically separated by a ferrite insulator and have a gas gap with an inert gas at high pressure. An additional electrode and a cathode electrode are placed in the gas gap. An additional electrode and cathode, as well as ion-forming targets located in the drift region of the vacuum chamber, are installed with the possibility of irradiation with laser pulses, and the electrodes in the gas gap with the possibility of blowing them with an inert gas. The generator is equipped with means for creating a longitudinal magnetic field, in the zone of influence of which ion-forming targets are mounted. A neutron-forming target is located on the inner surface of the chamber. All processes are synchronized with specified delay times using synchronization tools. 6 C.p. f-ly, 1 ill.

Description

The invention relates to neutron technology, to the field of constructing means for generating neutron radiation fluxes and can be used in nuclear geophysics, neutron-activation analysis and other fields of nuclear engineering and technology.

The aim of the invention is also to exacerbate the pulse front of the electron beam and increase the electron energy at the beginning of the electron current pulse.

The design of the inventive pulsed neutron generator is shown in the drawing.

The generator comprises a sealed cylindrical housing 1. The housing is divided into a number of zones, each of which has its own means of functioning. One of the zones is formed by a double-winding transformer containing the first winding 2, the second winding 3. The core 4 is predominantly made of ferrite or electrotechnical iron, as a good conductor, filler 5. Inside the transformer there is a hollow electrode 6 of the forming line, mounted on insulators 7. 8 The filler is oil, glycerin.

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deionized water. The transformer windings are electrically connected to the housing and the pulse power unit 9. Insulators 7, 8 are sealed in the housing.

The cathode consists of a cathode electrode 10 and the cathode 11 itself and is hermetically fixed in the cathode insulator 12. An additional electrode 13 is fixed in the insulator 8, separated from the cathode electrode 19 by a gas gap 14 filled with an inert gas (e.g., nitrogen) at high pressure ( about 20 atm). The cathode electrode 10 is connected to the mass through an inductance (not shown in the drawing) or ferrite 12 if it is sufficiently conductive. A gas convection means 15 (e.g. a fan) is installed in the gas gap 14. An additional electrode 13 and a cathode electrode 10 with a gas gap form a second zone, hermetically isolated from the zone of the transformer. Moreover, the additional electrode 13 is a continuation of the electrode 6 of the forming line. An optical window 16 for introducing laser radiation is made in the housing of the second zone. A laser 17 is used for this radiation, the rays of which are transported into the zone by means of a reflecting mirror 18 and a focusing and scanning system 19.

The third zone is a vacuum chamber 20 and is sealed off from the second zone by an insulator 12. Anode 21 is installed in the vacuum chamber, made in the form of an end wall with a passage hole 22, and Cathode-11 is made in the form of a truncated cone mainly of graphite. The forming line electrode 6, the additional electrode 13, the cathode electrode 10 and the cathode 11 are mounted coaxially with the axis of the generator, the apex of the cathode 11 being located near the passage hole 22. Behind the anode at predetermined distances from the generator axis, at selected distances from each other plasma-forming targets 23, the first of which is made of a conductive material and is installed following the anode 21 in electrical contact with it. The rest are installed in isolation from the anode on the means 24 for their fixation (for example, wire in the form of a spiral).

A portion of the vacuum chamber 20 forms a drift chamber 25. An optical window 26 for laser radiation is also provided in the housing in the area of the drift chamber in the housing. To irradiate the targets 23, as well as the cathode 11, the generator comprises a laser 27, a reflecting mirror 28, a multi-plate optical plate 29, and a system for focusing and scanning laser radiation 30 (in this case, for all targets at once). Around the targets 23, magnetic focusing lenses 31 are mounted in the housing. Vacuum

the chamber through the nozzle 32 is connected to a vacuum pump 33 for this part of the generator; on the inner end surface of the generator in the area of its drift chamber, a neutron-forming ion target 34 is mounted symmetrically with respect to the axis. To synchronize the formation processes, laser irradiation an additional electrode 13. of the cathode 11,

5 targets 23 with given delay times the generator contains a remote control 35 ... NII. :. -;. ; .:, -.-. ; . ; . L; :

A pulsed neutron generator operates as follows.

0, as a result of a specially selected discharge mode, explosive emission arises and plasma forms at cathode 11. Prior to the formation of this plasma, the first of the ion-forming targets 23 is irradiated with a laser pulse, owing to which, at the time of the explosion to this point and the mission, an anode hole 22 has a bunch of laser plasma with a surface close to flat. This contributes to the formation of

0 electron beam along the axis of the generator.

The implementation of the cathode insulator or part thereof of ferrite, and the cathode of graphite, previously irradiated with a laser, contributes to a significant exacerbation

5 of the pulse front of the electron beam and an increase in the electron energy at the beginning of the electron current pulse.

Electrons from the cathode plasma are accelerated to a planar laser-plasma

0 to the anode formed at the passage hole. The passage through the anode, an electron beam with a current greater than the limiting one, is locked in the drift chamber 25 and forms an electron above the second target 23

5 cloud. Thanks to synchronization means using the control panel 35 and one of the beams of the plasma forming system (27-30), by the time the electron beam is locked, the plasma bunch from the second target reaches the central axial zone and interacts with the electron beam. Due to this interaction, the bulk charge of the electron cloud of the beam is compensated by the plasma of the ion source

5 (second 23) and the electrons begin to move, the ions accelerate along the axis of the generator. This is facilitated by the effect on the electron cloud of the magnetic field of the focusing lenses 31. I will adjust the number of ions in the second laser bunch in place

blocking the electron beam (for example, by changing the energy and degree of focusing of laser radiation on a given target 23), can be used either as a source of accelerated ions, by introducing a transport channel into it, or, as in the proposed proposal, to generate a neutron flux.

Neutron flux is generated due to nuclear reactions. BeVd, n / B10, T / d, p / He or D / d, p / He3 under the influence of the corresponding accelerated ions on a neutron-forming target 34 mounted on the path of accelerated ions. This neutron generation scheme is generally implemented in a known generator.

A significant difference between the claimed technical solution and the known factor is the use of accelerating voltage pulse fronts and an electron beam in the proposed generator system of laser sharpeners. This became possible due to the introduction of a second zone into the generator with an additional electrode 13 and a cathode electrode 10 separated from each other by a gas gap 14. Before the breakdown charge is accumulated on the pulse arrester (the arrester can be represented as the capacitance between the electrodes - housing 1 and electrode 6 a forming line with a dielectric fluid 5) an additional electrode 13 is irradiated with weakly focused laser radiation using a system of elements t7-19.16. The laser pulse serves as a trigger for the accelerating voltage pulse arising on the electrode 13. As a result, the pulse itself appears with a shortened front through a gas gap filled with an inert gas, at high pressure, the voltage pulse charges the cathode electrode and the condition of explosive emission arises at cathode 11. By the moment of arrival of the accelerating voltage pulses, the cathode is also irradiated with a weakly focused laser pulse (one of the beams of a multipath plasma former). As a result of preliminary irradiation of the cathode and explosive emission, an electron beam pulse is also generated with a shortened front. This process is also facilitated by the shape of the cathode in the form of a truncated cone, its location with a pointed end near the anode hole 22, as well as ferrite filling in the insulator around the cathode.

Further, the process of formation of the ion beam and neutron flux occurs according to a well-known scheme, to prevent excessive heating in the frequency mode and

destruction of electrode systems (13, 10), the electrodes are blown with an inert gas using a fan.

It has been established that, as a result of the use of the 5th system of a double sharpener of the fronts of the pulses of the accelerating voltage and the beam of electrodes, it is possible to sharply change the spectrum of accelerated ions in the direction of increasing Experimental data show 10 that an increase of 2–3 times or more is possible without loss of the amount of ions themselves in the stream. The duration of the pulse fronts decreases and the coefficient of conversion of the energy of the electron beam Ne to the energy of the ion beam NI increases from 3 to 10% or more.

As a material of plasma-forming targets, it is possible to use TID, ZrD, neutron-forming targets - Be, D, 0 T, etc.

A further increase in the ion energy and, as a consequence, the resource of the ion-forming target in the proposed proposal is carried out using targets selected by 5 in an amount of more than two. Each subsequent target operates in the second, on. Zvol thereby reduce the load on each of them individually and increasing

ion acceleration effect.

0 Plasma formation processes can be synchronized on targets by selecting various degrees of focusing of rays on the target and by selecting distances between the targets and the axis of the drift 5 frvry camera. On the other hand, in order to limit in space the process of plasma formation on targets 23, the second and subsequent targets are preferably provided with slotted diaphragms (not shown in the drawing).

The generator assumes the availability of technical parameters for the electron beam: Its 200-500 KeV. I - 5-15 kA. g 10-30 not,% 2 not. 1 trace up to 50 Hz, where Its is the electron energy; I is the beam current; g-duration 5 pulses; TF - the duration of the front of the electron beam; Tsl is the pulse repetition rate.

For neutrons, Nn 109-10 neutrons / imp; units up to 50 Hz; Gimp 8-15 not, 0 neutron energy is 0.8-2.5 MeV.

Nuclear reactions of the type D + D (En ~ 2.5 MeV), T + D (En ~ 14 MeV), Be + D (En ~ 0.5-8 MeV), etc. are used.

The resource of use is on the order of 106 times, 5, but an increase of up to 108 and more times is possible. The width of the ion beam on the neutron-forming target is about 100 mm, and the beam divergence is 20 °.

As follows from the above data, the technical parameters of the claimed generator are much better than those of the known generator. Increased conversion efficiency reduces its energy consumption.

Formulas of the invention 1. A pulsed neutron generator containing a sealed cylindrical body, inside of which a cathode is mounted on an insulator along its longitudinal axis, connected to an accelerating voltage source, an anode made in the form of an end wall with a passage hole, coaxial with the cathode of the vacuum chamber formed inside the case by a sealed installation of a cathode insulator, and a cylindrical drift chamber located behind the anode coaxially with the vacuum chamber, flame-forming targets, the first of which are installed immediately behind the anode, and the second along the axis after the first one at a predetermined distance from the anode, a neutron-forming target on the inner surface of the drift chamber, a multipath laser plasma former with a system for generating, focusing and scanning laser radiation, synchronized with the accelerating source voltage, in the case of the fact that, in order to reduce power consumption, increase the density of the neutron flux in a pulse while decreasing its duration and increasing the life of the generator, d is made integral, consisting of the cathode itself in the form of a truncated cone, its apex facing the anode, and the cathode electrode, and is connected to the accelerating voltage source through an additional electrode isolated from the cathode electrode and placed together with the latter in the gas gap filled with the possibility of blowing with an inert gas at high pressure and formed between the vacuum chamber and the accelerating voltage source, made in turn in the form of a pulse transformer, the secondary winding orogo included between the body and

the electrode of the forming line, to which the additional electrode is connected, while the additional electrode and cathode are installed in the housing with the possibility of heating them with a weakly focused laser beam, act as sharpeners of the fronts of the accelerating voltage pulses and the electron beam, respectively, and the multi-beam laser plasma generator is equipped with synchronization means heating and plasma processes with predetermined delay intervals.

2. The generator according to claim 1, characterized in that, in order to sharpen the front of the electron beam pulse and increase the electron energy at the beginning of the electron current pulse, the cathode insulator is made of ferrite and the cathode is made of graphite.

3. The generator according to claim 1, characterized in that one of the beams of a multipath plasma former is used to heat the cathode.

"4. The generator according to claims 1 and 3, on the basis of which and so on. that the air former is made with a multi-wedged optical plate mounted in a laser radiation forming system and separated by focusing and scanning beams on the cathode and plasma forming targets.

5. Popp generator 1, 3, 4, because of the fact that the number of plasma-forming targets is more than two.

6. The generator according to claims 1, 3-5, with respect to the fact that the first plasma-forming target is made conductive, electrically connected to the anode, the rest at selected distances from each other each other is mounted at a different predetermined distance from the axis of the drift chamber, isolated from the anode, and used together with the first to process plasma formation with predetermined delay times.

7. The generator according to claims 1, 4-6, and so on, and that the second and subsequent targets are provided with space-delimiting and space-correcting plasma formation processes from them with slit diaphragms.