Direct-current high-voltage pulse working high-current pulse neutron generator

Abstract

The invention provides a direct-current high-voltage pulse working high-current pulse neutron generator, and relates to the technical field of neutron generators, and the direct-current high-voltage pulse working high-current pulse neutron generator comprises a main arc power supply module (3), a high-voltage acceleration power supply module (9) and a neutron tube (12). According to the high-current pulse neutron generator, pulse parameters can be adjusted, implementation is simpler, the neutron pulse width is widened to several ms from sub-mu s, the application field of the high-current pulse neutron generator can be widened, and for example, an ms-level high-current pulse neutron source can be applied to mass flow velocity and component measurement based on neutron activation.

Description

Technical Field

[0001] The invention relates to the technical field of high-current pulse neutron generators, and in particular to a high-current pulse neutron generator operating with direct current high-voltage pulses. Background Art

[0002] The vacuum arc ion source containing hydrogen (deuterium) electrodes is sometimes also called a spark ion source. It originated in the 1950s and is mainly used to generate high-current pulsed hydrogen (deuterium) ion beams. Compared with traditional ion sources, this ion source does not require the introduction of additional neutral gas components during the discharge pulse process. Many metal materials located in the transition zone of the periodic table absorb a large amount of hydrogen through the exothermic process and store hydrogen in solid materials, with extremely high hydrogen storage density. The vacuum arc pulsed ion beam containing hydrogen (deuterium) electrodes is mainly used in high-current pulsed neutron generators, which are special neutron sources that can generate strong pulsed neutrons in a shorter pulse width. In terms of principle and structure, it is a miniature low-energy particle accelerator, mainly composed of a vacuum arc ion source, a beam optical system, a target and other auxiliary components. It is usually compact in structure, and each component is encapsulated in a ceramic tube or a glass tube to form a special electric vacuum device (usually called a neutron tube), which is combined with an external power supply system to form a high-current pulsed neutron generator. Under the action of large current, the deuterium ion source electrode releases deuterium gas and metal vapor, and is ionized to produce high-density plasma containing deuterium ions and other metal ions. After expansion through the expansion cup, it is accelerated by high voltage extraction in the beam optical zone, bombarding the deuterium target or tritium target, and a thermonuclear reaction occurs to produce neutrons. Neutron tubes based on Penning and radio frequency ion sources usually work in continuous mode, and the ion current intensity is usually in the order of hundreds of μA; while high-current pulsed neutron generators are significantly different. The working current intensity of this type of neutron generator is usually in the order of hundreds of mA to A, and the working pulse width ranges from sub-μs to several ms. It has the significant characteristics of high current, high pulse neutron yield, and compact size. It is widely used in important fields such as oil well logging, chemical warfare agent detection, contraband detection, uranium mine detection, biomedicine, deep earth and extraterrestrial body detection.

[0003] High-current pulsed neutron generators usually use pulsed high voltage to accelerate ion target to produce pulsed neutrons. The pulsed high voltage is usually generated by a high-voltage pulse transformer, and the primary current of the pulse transformer is usually generated by a high-voltage and high-current switch with a repetition frequency of several kV. Compared with DC high voltage, the pulsed high voltage has a short action time, and the insulating material can usually withstand a higher pulse voltage amplitude. The pulsed high voltage driving method used in the neutron generator can easily achieve a smaller volume size. For example, the high-current pulsed neutron generator currently produced by the All-Russian Institute of Automation in Russia uses a pulsed high voltage acceleration method, which has a small volume size and a high acceleration voltage.

[0004] However, the pulse acceleration method is limited by the high-voltage pulse transformer and the repetition frequency high-voltage switching device, which makes the neutron generator pulse width short and the output neutron pulse width cannot be adjusted. At the same time, the design requirements for the pulse transformer parameters are extremely high, and it is affected by the distribution parameters of the overall assembly structure of the generator, making the pulse transformer parameter design and control more difficult; and the long-life repetition frequency high-voltage switching device is also a key technical difficulty that this technical solution needs to overcome. For example, the Chinese invention patent with application number CN 202110388701.7 discloses a pulse power supply system and a neutron generator. The high-voltage acceleration power supply adopts a pulse voltage drive method and uses four pulse transformers to achieve positive and negative pulse acceleration high voltage, as well as the ion source main arc drive current suspended in the high-voltage acceleration voltage.

[0005] Therefore, this paper proposes a working and driving mode of a high-current pulsed neutron generator that uses DC high-voltage acceleration and pulse mode. The pulse parameters can be adjusted and the implementation is simpler, and the neutron pulse width is widened from sub-μs to several ms, which helps to broaden the application field of high-current pulsed neutron generators. For example, ms-level high-current pulsed neutron sources can be used in mass flow rate and composition measurement based on neutron activation. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a DC high-voltage pulse working high-current pulse neutron generator. The present invention aims to overcome the shortcomings of the prior art, such as the difficulty in designing a pulse transformer, the difficulty in implementing a long-life high-voltage switch, and the difficulty in adjusting the pulse width. The present invention is specifically implemented through the following technical solutions:

[0007] A DC high-voltage pulse working high-current pulse neutron generator comprises a main arc power supply module, a high-voltage acceleration power supply module and a neutron tube, wherein: a DC power supply and a main arc power supply ion source, an energy storage capacitor and a main switch are arranged in the main arc power supply module; the main arc power supply ion source and the energy storage capacitor are connected in parallel to the DC power supply, the main switch is placed in the branch where the main arc power supply ion source is located, and the main arc power supply ion source generates a current pulse waveform by controlling the conduction time of the main switch;

[0008] The high-voltage acceleration power supply module is provided with a voltage doubling circuit structure to amplify the input voltage and output it;

[0009] The neutron tube includes a neutron tube ion source, a beam optical system and a target; the neutron tube ion source generates plasma by discharge, and is accelerated into an ion beam by the beam optical system, and the accelerated ion beam bombards the target to generate neutrons;

[0010] The main arc power supply module provides pulse current for the neutron tube, discharges the neutron tube ion source in the neutron tube, and generates plasma; the high-voltage acceleration power supply module provides DC voltage for the beam optical system, and the plasma beam is accelerated to bombard the target, and a fusion reaction occurs to generate neutrons.

[0011] Optionally or preferably, a current limiting resistor R2 is further provided in the main arc power supply module; the current limiting resistor R2 is connected in series with the main arc power supply ion source to adjust the current amplitude flowing through the main arc power supply ion source.

[0012] Optionally or preferably, the high-voltage acceleration power supply module adopts a voltage doubling circuit structure, specifically:

[0013] The initial input voltage U in It is transformed into positive and negative symmetrical AC voltages U1 and -U1, and the multi-stage capacitor replenishes the circuit energy between pulse intervals, recharging the positive and negative symmetrical circuit to the initial value of the acceleration voltage; the total energy storage capacitor capacity C0 of the high-voltage acceleration power module satisfies:

[0014] C0·ΔU=I·Δt

[0015] Among them, ΔU is the voltage drop of the high-voltage acceleration power module during the load working cycle; I is the load current intensity of the high-voltage power supply; Δt is the load time period of the high-voltage power supply.

[0016] Optionally or preferably, the main arc power supply module, the high-voltage acceleration power supply module and the neutron tube are all installed in the generator housing; a feed connector is provided on the generator housing; the main arc power supply module and the high-voltage acceleration power supply module are both electrically connected to an external controller via the feed connector.

[0017] Optionally or preferably, the generator housing is filled with an insulating medium; the insulating medium is one of transformer oil, solid potting or insulating gas.

[0018] Optionally or preferably, the adjustable current amplitude range of the pulse current provided by the main arc power supply module is 1-1000A, and the adjustable pulse width range of the pulse current is 100ns-10ms.

[0019] Optionally or preferably, the trigger voltage output by the main arc power supply module is 1-10 kV.

[0020] Optionally or preferably, the voltage output of the high-voltage acceleration power module is in the range of 10-200 kV, and the pulse output current is in the range of 10 mA-10 A, and usually a larger pulse current intensity is output at a smaller working pulse width.

[0021] Based on the above technical solution, the following technical effects can be produced:

[0022] The invention provides a high-current pulse neutron generator operating in direct current high-voltage pulse mode, which can realize adjustable pulse parameters and is simpler to realize, and can widen the neutron pulse width from sub-μs to several ms, thus helping to broaden the application field of the high-current pulse neutron generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0024] Figure 1 It is a DC high-voltage pulse working high-current pulse neutron generator in the present invention;

[0025] Figure 2 is a circuit structure diagram of the power module in the present invention;

[0026] Figure 3 This is a circuit diagram of a double voltage high-voltage acceleration module in the present invention;

[0027] Figure 4 This is a circuit schematic diagram of a DC high-voltage pulse working high-current pulse neutron generator in the present invention;

[0028] Figure 5 The working principle simulation calculation of the DC high-voltage pulse working high-current pulse neutron generator in the present invention;

[0029] In the figure: 1-feed connector, 2-main arc power module control connection line, 3-main arc power module, 4-main arc power module output connection line, 5-generator housing, 6, controller and neutron generator connection line, 7-controller, 8-high voltage acceleration power module control connection line, 9-high voltage acceleration power module, 10, high voltage acceleration power module output connection line, 11-insulating medium, 12-neutron tube,

[0030] 301- DC power supply, 302- main arc power supply ion source, 303- energy storage capacitor, 304- main switch. DETAILED DESCRIPTION

[0031] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] like Figure 1-Figure 5 As shown:

[0035] This embodiment provides a DC high-voltage pulse working high-current pulse neutron generator, comprising a main arc power supply module 3, a high-voltage acceleration power supply module 9 and a neutron tube 12, wherein:

[0036] The main arc power supply module 3 is provided with a DC power supply 301, a main arc power supply ion source 302, an energy storage capacitor 303 and a main switch 304; the main arc power supply ion source 302 and the energy storage capacitor 303 are connected in parallel to the DC power supply 301, and the main switch 304 is placed in the branch where the main arc power supply ion source 302 is located, and the main arc power supply ion source 302 generates a current pulse waveform by controlling the conduction time of the main switch 304; in this embodiment, the on-resistance of the main arc power supply ion source 302 after breakdown is less than 1Ω; the current amplitude flowing through the main arc power supply ion source 302 is determined by the current limiting resistor R2;

[0037] The high-voltage acceleration power supply module 9 is provided with a voltage doubling circuit structure to amplify the input voltage and output it;

[0038] The neutron tube 12 includes a neutron tube ion source, a beam optical system and a target; the neutron tube ion source can be ionized into plasma and accelerated by the beam optical system, and the accelerated ion beam bombards the target to generate neutrons;

[0039] The main arc power supply module 3 provides a pulse current to the neutron tube 12, discharges the neutron tube ion source in the neutron tube 12, and generates plasma; the high-voltage acceleration power supply module 9 provides a DC voltage to the beam optical system, and the ion beam is accelerated to bombard the target, and a thermonuclear reaction occurs to produce neutrons.

[0040] In this embodiment, a current limiting resistor R2 is further provided in the main arc power supply module 3 ; the current limiting resistor R2 is connected in series with the main arc power supply ion source 302 to adjust the current amplitude flowing through the main arc power supply ion source 302 .

[0041] In this embodiment, the high-voltage acceleration power supply module 9 adopts a voltage doubling circuit structure, and is described as a double voltage circuit structure:

[0042] The initial input voltage U inIt is transformed into positive and negative symmetrical AC voltages U1 and -U1, and the multi-stage capacitors replenish the circuit energy between pulse intervals, recharging the positive and negative symmetrical circuit to the initial value of the acceleration voltage; Figure 3 As shown, the high voltage end of the AC voltage is grounded, and the voltage multiplication level is N. Ideally, the output voltage can reach 2N times of the AC voltage U1; the total energy storage capacitor capacity C0 of the high voltage acceleration power module 9 satisfies:

[0043] C0·ΔU=I·Δt

[0044] Wherein, ΔU is the voltage drop of the high-voltage acceleration power module 9 during the load working cycle; i is the load current intensity of the high-voltage power supply; Δt is the load time period of the high-voltage power supply;

[0045] In this embodiment, the voltage drop ΔU is approximately the initial input voltage U in 10% of the total current; I is also the beam current intensity of the neutron tube 12, which is in the order of hundreds of mA to A.

[0046] In this embodiment, the main arc power supply module 3, the high-voltage acceleration power supply module 9 and the neutron tube 12 are all installed in the generator housing 5; the generator housing 5 is provided with a feed connector 1; the main arc power supply module 3 and the high-voltage acceleration power supply module 9 are electrically connected to the external controller 7 through the feed connector 1.

[0047] In this embodiment, the generator housing 5 is filled with an insulating medium 11; the insulating medium 11 is one of transformer oil, solid potting or insulating gas. The miniaturization of the neutron generator can be achieved by filling the insulating medium.

[0048] In this embodiment, in the fields of oil well logging, uranium mine detection, etc., the neutron pulse width parameter usually required is 1μs~20μs. In order to meet the detection requirements, in this embodiment, the adjustable current amplitude range of the pulse current provided by the main arc power supply module 3 is 1-1000A, and the adjustable pulse width range of the pulse current is 100ns-10ms.

[0049] In this embodiment, the trigger voltage output by the main arc power supply module 3 is 1-10 kV. In this embodiment, the trigger voltage is 5 kV.

[0050] The design structure, function and connection form disclosed in this article can be realized by other means. For example, the embodiments described above are only schematic. For example, the working mode of the neutron tube can also choose to suspend the ion source above the accelerating high voltage. At this time, an isolated power supply method is required to power the main arc power supply of the ion source; for example, the voltage doubling circuit can also adopt a single voltage circuit topology according to practical conditions; the energy storage capacitor in the main arc power supply module can also adopt other current pulse generation methods, such as using a pulse forming line, inductive energy storage, etc. to generate current pulses; in addition, the various functional components in the various embodiments of this article can be integrated into one functional component, or each functional component can exist physically separately, or two or more functional components can be integrated into one functional component.

[0051] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A DC high-voltage pulse working high-current pulse neutron generator, characterized in that: It comprises a main arc power supply module (3), a high-voltage acceleration power supply module (9) and a neutron tube (12), wherein: The main arc power supply module (3) is provided with a direct current power supply (301), a main arc power supply ion source (302), an energy storage capacitor (303) and a main switch (304); the main arc power supply ion source (302) and the energy storage capacitor (303) are connected in parallel to the direct current power supply (301); the main switch (304) is placed in the branch where the main arc power supply ion source (302) is located, and the main arc power supply ion source (302) generates a current pulse waveform by controlling the conduction time of the main switch (304); the high-voltage acceleration power supply module (9) is provided with a voltage doubling circuit structure to amplify the input voltage and output it; The neutron tube (12) comprises a neutron tube ion source, a beam optical system and a target; the neutron tube ion source generates plasma by discharge, which is accelerated into an ion beam by the beam optical system, and the accelerated ion beam bombards the target to generate neutrons; The main arc power supply module (3) provides a pulse current for the neutron tube (12), discharges the neutron tube ion source in the neutron tube (12), and generates plasma; the high-voltage acceleration power supply module (9) provides a direct current voltage for the beam optical system, and the ion beam is accelerated to bombard the target, generating a fusion reaction to generate neutrons.

2. A DC high voltage pulse working high current pulse neutron generator according to claim 1, characterized in that: A current limiting resistor R2 is also provided in the main arc power supply module (3); the current limiting resistor R2 is connected in series with the main arc power supply ion source (302) and is used to adjust the current amplitude flowing through the main arc power supply ion source (302).

3. A DC high voltage pulse working high current pulse neutron generator according to claim 1, characterized in that: The high-voltage acceleration power supply module (9) adopts a voltage doubling circuit structure, specifically: The initial input voltage U in The circuit is converted into positive and negative symmetrical AC voltages U1 and -U1, and the multi-stage capacitors supplement the energy of the circuit between pulse intervals, so as to recharge the positive and negative symmetrical circuit to the initial value of the acceleration voltage; the total energy storage capacitor capacity C0 of the high-voltage acceleration power supply module (9) satisfies: C0·ΔU=I·Δt Wherein, ΔU is the voltage drop of the high-voltage acceleration power module (9) during the load working cycle; I is the load current intensity of the high-voltage power supply; and Δt is the load time cycle of the high-voltage power supply.

4. A DC high voltage pulse working high current pulse neutron generator according to claim 1, characterized in that: The main arc power module (3), the high-voltage acceleration power module (9) and the neutron tube (12) are all installed in a generator housing (5); a feed connector (1) is provided on the generator housing (5); the main arc power module (3) and the high-voltage acceleration power module (9) are both electrically connected to an external controller (7) via the feed connector (1).

5. A DC high voltage pulse working high current pulse neutron generator according to claim 4, characterized in that: The generator housing (5) is filled with an insulating medium (11); the insulating medium (11) is one of transformer oil, solid potting or insulating gas.

6. A DC high voltage pulse working high current pulse neutron generator according to claim 1, characterized in that: The adjustable current amplitude range of the pulse current provided by the main arc power supply module (3) is 1-1000A, and the adjustable pulse width range of the pulse current is 100ns-10ms.

7. A DC high voltage pulse working high current pulse neutron generator according to claim 1, characterized in that: The trigger voltage output by the main arc power supply module (3) is 1-10 kV.

8. The DC high-voltage pulse working high-current pulse neutron generator according to claim 1 is characterized in that: The voltage output by the high-voltage acceleration power supply module (9) is in the range of 10-200 kV, and the pulse output current is in the range of 10 mA-10 A. Usually, a larger pulse current intensity is output when the working pulse width is smaller.

Images