RU2553088C1 - Braking radiation pulse shaping device - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: braking radiation pulse shaping device contains the generator with the inductive storage and the electrically fused series connected conductors with different diameters, the accelerating tube with the vacuum diode with the "inversed" cathode, the attenuating discharger, the diameter d_i and the length l_i of the electrically fused conductors 2 are determined by the formulas:

, where d_i - is the diameter of the electrically fused conductor; W - the power stored in the generator; ρ - wave resistance of discharge loop;

, where l_i - length of series connected electrically fused conductors; S_i - area of their cross section, γ - specific electric resistance; ρ - wave resistance of discharge loop; k≥0.03 - empirically found proportionality coefficient.

EFFECT: shaping of a series of sequence of brake radiation impulses with the minimum size of a focal spot for registration of fast processes.

2 cl, 4 dwg

Description

The invention relates to high-voltage pulsed technology, in particular, to the formation of pulses in an accelerating tube, and can be used in a direct-acting pulsed X-ray accelerator with electric exploding conductors to obtain successive high-intensity bursts of bremsstrahlung for recording fast processes in optically dense media.

A device for implementing a method of generating single pulses of bremsstrahlung for recording fast processes in X-ray installations, described in the article K.F. Zelinsky, I.A. Troshkina, V.A. Zuckerman's “Two-electrode pulsed x-ray tube”, PTE, 1963, No. 2, p. 140, consisting of an anode, cathode, current lead connected to the anode, an output window and an insulating casing.

The disadvantage of the described device is the inability to generate a series of consecutive pulses of bremsstrahlung necessary to obtain dynamic data on the development of fast processes.

The closest and taken as a prototype is the device described in the patent of the Russian Federation No. 2113052, IPC Н03K 3/53 entitled "Method for generating a pulse of bremsstrahlung of complex shape and a device for its implementation", containing a pulse voltage generator on electrically explosive conductors, sharpening the spark gap and accelerator tube.

The disadvantages of the described device are:

- the focal spot of the radiation generated in the accelerator tube with a “direct” cathode has large dimensions (more than 20 mm in both directions), which is unacceptable for x-ray diffraction of fast processes, since one of the main requirements for the radiation source is the minimum size of the focal radiation spots;

- instability of the position of the focus of radiation on the anode (target);

- the large size and complexity of the design (to accommodate two pulse voltage generators on electrically explosive conductors requires a large area of the room).

The objective of the invention is to provide a device for forming a series of successive pulses of bremsstrahlung with a minimum focal spot size for recording fast processes.

The technical result that allows us to solve the problem lies in the fact that the proposed relations determine the parameters of electroexplosive conductors to obtain a series of successive high-voltage pulses in a direct-acting accelerator with a “reverse” cathode in the accelerator tube to form a series of successive bremsstrahlung pulses in the accelerator tube diode, allowing to register fast processes.

This is achieved by the fact that in the device containing the pulse voltage generator on the electric exploding conductors, the sharpening discharger and the accelerating tube, according to the invention, the accelerating tube is equipped with a vacuum diode with a “reversed” cathode, the electric exploding conductors are made with different diameters and connected in series, the length and the diameter of the exploding conductors is determined by the following formulas:

, где

where

d _i is the diameter of the electroexplosive conductor;

W is the energy stored in the generator;

ρ is the wave resistance of the discharge circuit.

, где

where

l _i is the length of the series-connected electrically explosive conductors;

S _i is the cross-sectional area of series-connected electrically explosive conductors;

γ is the electrical resistivity;

ρ is the wave impedance of the discharge circuit;

k≥0.03 - empirically determined coefficient of proportionality.

In addition, the generator with inductive storage is assembled according to the Arkadyev-Marx scheme.

The presence in the claimed invention features that distinguish it from the prototype, allows us to consider it appropriate to the condition of "novelty."

New features (namely, that the accelerator tube is equipped with a vacuum diode with a “reverse” cathode, while the parameters of the exploding conductors, length and diameter, are determined by the formulas:

, где

where

d _i is the diameter of the electroexplosive conductor;

W is the energy stored in the generator;

ρ is the wave resistance of the discharge circuit.

, где

where

l _i is the length of the series-connected electrically explosive conductors;

S _i is the cross-sectional area of series-connected electrically explosive conductors;

γ is the electrical resistivity;

ρ is the wave impedance of the discharge circuit;

k≥0.03 - an empirically determined coefficient of proportionality) are not identified in technical solutions of a similar purpose. On this basis, we can conclude that the claimed invention meets the condition of "inventive step".

The invention is illustrated in the following drawings.

Figure 1 presents a diagram of a device for generating a pulse of bremsstrahlung.

Figure 2 shows the characteristic oscillograms of the mode of generation of two consecutive pulses of bremsstrahlung.

Figure 3 shows the x-ray of the static position of the model assembly for an example of a specific implementation of the proposed device.

Figure 4 shows the x-ray of the explosive experiment for two-frame registration of the expansion of the steel plate 9.

The following notation is introduced in the drawings:

1 - pulse voltage generator;

2 - exploding conductors;

3 - sharpening spark gap;

4 - accelerating tube;

5 - pulses of bremsstrahlung;

6 - current through the accelerating tube

7 - voltage on the accelerating tube

8 - current through electric explosive conductors

9 - steel plate;

10 - foam plates;

11 - lead foil;

12, 13 - layers of explosive.

The device operates as follows.

When the pulse voltage generator 1 is triggered, a consecutive explosion of conductors 2 of various diameters and lengths, calculated from the proposed dependencies, by the total current flowing through them, generating a series of high-voltage pulses, occurs. Serial high-voltage pulses through the sharpening spark gap 3 are switched to the accelerating tube 4, where as a result of the breakdown of the vacuum diode a series of successive pulses of bremsstrahlung is formed. Using the principle of a “reversed” cathode in the diode of an accelerating tube allows us to obtain the minimum size of the focal spot of radiation.

The calculation of the parameters of electroexplosive conductors was carried out using the criteria for obtaining the maximum power value for accelerators with electric explosion of conductors formulated in the monograph “Pulse electron accelerators with inductive energy storage”, ed. V.P. Kovaleva, Snezhinsk, 2012

An example of a specific implementation.

The invention is implemented on the X-ray accelerator IGUR-3,5. The main parts of the accelerator are: inductive-capacitive energy storage device (IENE), consisting of an impulse voltage generator 1 assembled according to the Arkadyev-Marx scheme, and an inductive energy storage device, an explosion site for electrically explosive conductors 2, a sharpening spark gap 3 and an accelerating tube 4 with a vacuum diode, consisting of a cathode ring and an anode rod (the principle of the "inverse" cathode). The use of a “reverse” cathode in the diode of the accelerating tube allows one to obtain the minimum size of the radiation focal spot equal to the diameter of the anode rod.

Inductive energy storage, the explosion of conductors 2 and the sharpening spark gap 3 form a pulse formation system. When the pulse generator 1 is triggered, a sequential explosion of electrically exploding conductors 2 of different diameters by a common current occurs. The selection of electrically exploded copper conductors was carried out based on the calculation of the parameters of the discharge circuit and the design dimensions of the pulse generation system of the IGUR-3,5 accelerator (ρ = 7.8 Ohm, l ₁ + l ₂ = 4000 mm, where l ₁ , l ₂ are the lengths of consecutive conductors )

The diameter of the series-connected electroexplosive copper conductors is selected from the ratio

, где

where

d _i ≤0.48 mm (S _i ≤0.1 mm ² )

W is the energy stored in the Arkadyev-Marx generator.

The lengths of series-connected electrically exploding copper conductors are selected from the relation

l _i is the length of the series-connected electrically explosive conductors;

S _i is the cross-sectional area of series-connected electrically explosive conductors;

γ is the electrical resistivity of copper;

ρ is the wave impedance of the discharge circuit;

k≥0.03 - empirically determined proportionality coefficient

The calculations were carried out for series-connected conductors 0.08 mm≤d ₁ ≤0.12 mm and 0.14 mm≤d ₂ ≤0.45 mm, respectively 0.0064 mm ² ≤S ₁ ≤0.011 mm ² and 0.015 mm ² ≤S ₂ ≤0.16 mm ² , based on the condition for choosing the diameter of the conductor. The lengths of the series-connected conductors were selected based on the structural dimensions of the pulse formation system (l ₁ + l ₂ = 4000 mm).

Having transformed the last inequality, we obtained the condition for selecting the lengths of series-connected copper conductors depending on their cross-sectional area:

Substituting the cross-sectional values of conductors satisfying condition (1) in pairs into expressions (2), we obtain sets of lengths of electrically exploding conductors connected in series. The development of the regime for generating two consecutive pulses of bremsstrahlung consists in the selection of sets of series-connected conductors of different diameters to obtain the desired time interval between pulses and the maximum amplitudes of the successive pulses.

At the time of current interruption, two consecutive high-voltage pulses are formed in the IENE circuit on the high-voltage collector of the pulse formation system. Through the sharpening spark gap 3, the high-voltage pulses are switched into the accelerating tube 4. In a vacuum diode, during the breakdown of the cathode-anode gap, two consecutive bremsstrahlung pulses are generated.

Figure 2 shows the characteristic oscillograms of the mode of generation of two consecutive pulses of bremsstrahlung. On beam 5, two peaks of successive pulses of bremsstrahlung with a time interval between them of 1.72 μs are clearly visible. The oscillogram also shows the pulses of currents and voltages of the accelerator tube 6, 7, the current through electrically exploding conductors of different diameters 8. The use of the proposed device for generating pulses of bremsstrahlung made it possible to carry out multi-frame single-angle radiography of fast processes. Figure 3 shows the x-ray of the static position of the model assembly, consisting of a steel plate 9, foam plates 10, lead foil 11 and layers of explosive 12, 13. Figure 4 shows the x-ray of an explosive experiment on two-frame registration of expansion of a steel plate. The X-ray diffraction pattern clearly shows the position of the steel plate 9 at the time of recording t _γ1 = 37.5 μs and the position at the time t _γ2 = 39.1 μs.

The inventive device for generating pulses of bremsstrahlung has made it possible to form a series of successive pulses of bremsstrahlung with a minimum focal spot size for recording fast-moving processes, i.e. multi-frame single-angle radiography of fast processes.

For the claimed invention, in the form described in the claims, the possibility of implementing the device and the ability to ensure the achievement of the perceived by the applicant technical result is confirmed. Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (2)

1. Device for generating a bremsstrahlung pulse, comprising a generator with an inductive storage device and electrically exploding consecutively connected conductors of different diameters, an accelerating tube, sharpening a spark gap, characterized in that the accelerating tube is equipped with a vacuum diode with a “reversed” cathode, the length and diameter of the electrically exploding conductors determined by the formulas:

where
d _i is the diameter of the electroexplosive conductor;
W is the energy stored in the generator;
ρ is the wave impedance of the discharge circuit;

where
l _i is the length of the series-connected electrically explosive conductors;
S _i is the cross-sectional area of series-connected electrically explosive conductors;
γ is the electrical resistivity;
ρ is the wave impedance of the discharge circuit;
k≥0.03 - empirically determined coefficient of proportionality. 2. The device for generating a bremsstrahlung pulse according to claim 1, characterized in that the generator with inductive storage is assembled according to the Arkadyev-Marx scheme.

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