A terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma

Abstract

The invention discloses a terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma, and belongs to the field of terahertz wave technology. The terahertz radiation source comprises a vacuum diode assembly and a magnetized coaxial plasma gun assembly. The vacuum diode assembly comprises at least a diode cathode and a diode anode, and the magnetized coaxial plasma gun assembly comprises at least a solenoid coil, a fast gas injection valve, a coaxial gun inner electrode and a coaxial gun outer electrode. The invention generates a high-current relativistic electron beam through a vacuum diode assembly, and generates a magnetized plasma through a magnetized coaxial plasma gun assembly, forming a low-density electron beam injected into a high-density plasma, and exciting electromagnetic radiation with a frequency in the range of 0.1THz-10THz, covering the entire terahertz band.

Description

Technical Field

[0001] The invention relates to the technical field of terahertz waves, and in particular to a terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma. Background Art

[0002] Terahertz waves are electromagnetic radiation with a frequency range of 0.1THz-10THz. This frequency band is between the microwave band and the infrared band in the electromagnetic spectrum and is a transitional area for the study of electronics and photonics. Terahertz waves have high penetration, low energy, ultra-high bandwidth, spectral resolution, high resolution and water absorption characteristics, so they have important applications in many fields such as military, medicine, communications, materials science, astronomy, industrial testing, and homeland security.

[0003] Terahertz radiation sources are the basis for terahertz information systems to achieve information transmission, detection and perception, so their research has always been one of the important directions of terahertz research. Traditionally, there are two methods for developing terahertz radiation sources. One is to increase the frequency based on microwave radiation sources based on electronic methods, and the other is to reduce the frequency based on light sources based on photonic methods. However, these two radiation sources have various difficulties when working in the terahertz frequency band.

[0004] The output frequency range of traditional terahertz radiation sources is mostly limited to 1-3THz, the tuning method is relatively complex, and the energy conversion efficiency is low. This problem is an important bottleneck problem faced by the development of terahertz science and technology, and it is also a key problem that needs to be solved urgently in the field of terahertz research. Summary of the invention

[0005] The object of the present invention is to provide a terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma, aiming to solve one of the technical problems existing in the above-mentioned prior art. To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows:

[0006] A terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma, comprising:

[0007] A magnetized coaxial plasma gun assembly, the magnetized coaxial plasma gun assembly comprising a solenoid coil, a fast gas injection valve, a coaxial gun inner electrode and a coaxial gun outer electrode;

[0008] A vacuum diode assembly, the vacuum diode assembly comprising a diode cathode and a diode anode;

[0009] Among them, the inner electrode of the coaxial gun is located at one end of the outer electrode of the coaxial gun, and a vacuum chamber is formed between the inner electrode of the coaxial gun and the outer electrode of the coaxial gun, a plurality of the rapid gas injection valves are evenly arranged on the periphery of the outer electrode of the coaxial gun, the anode of the diode is installed in the inner electrode of the coaxial gun through a diode insulating support, the cathode of the diode is arranged at one end of the anode of the diode away from the insulating support of the diode, and the solenoid coil is installed on the periphery of the anode of the diode through a coil support.

[0010] The present invention generates a high-current relativistic electron beam through a vacuum diode component and a magnetized coaxial plasma gun component to generate a magnetized plasma, forming a low-density electron beam that is injected into a high-density plasma to excite electromagnetic radiation with a frequency in the range of 0.1THz-10THz, covering the entire terahertz band.

[0011] As a further technical solution of the present invention, an end of the inner electrode of the coaxial gun away from the diode insulating support is fixedly connected to an inner electrode connecting flange, and an end of the outer electrode of the coaxial gun close to the inner electrode connecting flange is fixedly connected to an outer electrode connecting flange, and the inner electrode connecting flange and the outer electrode connecting flange are fixedly connected via a ceramic insulating tube and a polytetrafluoroethylene insulating tube.

[0012] As a further technical solution of the present invention, a plurality of coaxial cable inner electrode connection pressing blocks are evenly arranged on the outer periphery of the inner electrode connection flange.

[0013] As a further technical solution of the present invention, a plurality of external electrode adapter blocks are evenly arranged on the outer periphery of the external electrode connecting flange.

[0014] As a further technical solution of the present invention, one end of the external electrode adapter block away from the external electrode connecting flange is fixedly connected to the external electrode extension flange.

[0015] As a further technical solution of the present invention, the side of the outer electrode epitaxial flange away from the outer electrode adapter block is fixedly connected to the coaxial cable outer electrode flange through a plurality of electrical connection columns.

[0016] As a further technical solution of the present invention, a plurality of connecting column insulating sleeves are fixedly connected between the outer electrode epitaxial flange and the coaxial cable outer electrode flange, and one connecting column insulating sleeve is correspondingly arranged for each electrical connecting column.

[0017] As a further technical solution of the present invention, a plurality of coaxial cable outer electrode connecting pressing blocks are evenly arranged on the outer periphery of the coaxial cable outer electrode flange.

[0018] As a further technical solution of the present invention, two plasma diagnosis upper windows are arranged on the periphery of the outer electrode of the coaxial gun, and the plasma diagnosis upper windows are used for measuring the magnetic field of the magnetized plasma.

[0019] As a further technical solution of the present invention, four plasma diagnostic horizontal windows are arranged on the periphery of the outer electrode of the coaxial gun, and the plasma diagnostic horizontal windows are used to measure the average density and radiation intensity of the magnetized plasma string.

[0020] The present invention has the following beneficial effects:

[0021] The present invention drives the vacuum diode assembly through a pulse power supply to make it explode and emit a high-current relativistic electron beam. The high-current relativistic electron beam has low density and long pulse width quality. It also generates a magnetized plasma through a magnetized coaxial plasma gun assembly. The magnetized plasma has a spherical mark magnetic field configuration to extend its life and has high density characteristics. When a low-density electron beam is injected into a high-density plasma, the electrons in the plasma will be repelled by the electron beam and then return to their original positions under the action of the restoring force, and finally form a plasma oscillation near the oscillation frequency of the plasma frequency, which is called a plasma tail field. The plasma tail field modulates the electron beam to achieve positive feedback interaction. When the modulation reaches the nonlinear stage, the system will excite electromagnetic wave radiation near the plasma frequency and its multiples. When the plasma density is 1.24×10 20 m -3 to 1.24×10 24 m -3 When in the range of 0.1 THz to 10 THz, the plasma frequency covers the entire terahertz band. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings.

[0023] Figure 1 It is a schematic diagram of the overall structure of the terahertz radiation source of the present invention;

[0024] Figure 2 is another schematic diagram of the overall structure of the terahertz radiation source of the present invention;

[0025] Figure 3 It is a schematic cross-sectional view of the overall structure of the terahertz radiation source of the present invention;

[0026] Figure 4 This is a schematic diagram of the principle of the electron beam driving terahertz radiation in the magnetized plasma of the present invention.

[0027] In the figure: 1. cathode of diode; 2. anode of diode; 3. solenoid coil; 4. rapid gas injection valve; 5. inner electrode of coaxial gun; 6. outer electrode of coaxial gun; 7. insulating support of diode; 8. inner electrode connecting flange; 9. outer electrode connecting flange; 10. ceramic insulating tube; 11. polytetrafluoroethylene insulating tube; 12. inner electrode connecting block of coaxial cable; 13. outer electrode adapter block; 14. outer electrode epitaxial flange; 15. electrical connection column; 16. outer electrode flange of coaxial cable; 17. insulating sleeve of connection column; 18. outer electrode connecting block of coaxial cable; 19. upper window of plasma diagnosis; 20. horizontal window of plasma diagnosis; 21. outlet flange of coaxial gun; 22. support frame; 23. support platform; 24. coil support; 25. gas injection window. DETAILED DESCRIPTION

[0028] 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.

[0029] In the description of the present invention, it should be understood that terms such as "up", "down", "left", "right", "front" and "back" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, and a specific direction structure and operation. Therefore, they should not be understood as limitations on the present invention.

[0030] In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] See also Figure 1-4 As shown, an embodiment of the present invention provides a terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma, including a vacuum diode assembly and a magnetized coaxial plasma gun assembly. A high-current relativistic electron beam is generated by the vacuum diode assembly, and a magnetized plasma is generated by the magnetized coaxial plasma gun assembly, forming a low-density electron beam injected into a high-density plasma, exciting electromagnetic radiation with a frequency in the range of 0.1THz-10THz, covering the entire terahertz band.

[0032] The vacuum diode assembly at least comprises a diode cathode 1 and a diode anode 2, and the magnetized coaxial plasma gun assembly at least comprises a solenoid coil 3, a fast gas injection valve 4, a coaxial gun inner electrode 5 and a coaxial gun outer electrode 6.

[0033] See also Figure 3 As shown, in this embodiment, the diode anode 2 is installed in the coaxial gun inner electrode 5 through the diode insulating support 7, and the diode cathode 1 is arranged in the diode anode 2 at one end away from the diode insulating support 7 and maintained in a high vacuum state, with a vacuum degree better than 10 -4 Pa. During operation, a negative high voltage (-1MV to -200kV) is applied to the cathode 1 of the diode to cause it to explode and emit a strong relativistic electron beam, while the diode anode 2 serves as an external electrode and is grounded. The diode anode 2 is fixed and pressed to the diode insulating support 7 by a fluororubber sealing ring to form a vacuum isolation state, and is electrically insulated from the electrode 5 inside the coaxial gun. It is worth noting that the structure of the vacuum diode assembly is very important for the quality of the electron beam, and has an important influence on the beam current, electron beam energy and energy dispersion. In order to realize a high-power, long-pulse terahertz radiation source, the relativistic electron beam needs to have a long pulse width, usually in the range of nanoseconds to microseconds (usually 100ns), to ensure the continuity and stability of the radiation.

[0034] See also Figure 3 As shown, in this embodiment, the solenoid coil 3 is installed on the periphery of the diode anode 2 through the coil support 24, and the solenoid coil 3 is wound on the coil support 24 by enameled wire and filled with insulating glue. Energy is stored through a capacitor (capacitance value is in the range of 100μF to 1mF), and the load solenoid coil 3 is energized after the thyristor switch is turned on, generating a pulse current (current size is in the range of 0 to 150kA), and forming an approximately stable bias magnetic field (magnetic field maximum value is in the range of 0 to 0.5T) during the plasma formation period, which is used for the formation of the plasma ball mark magnetic field configuration. The formation of the plasma ball mark magnetic field configuration can delay the plasma life and will affect the time length of the terahertz wave pulse. By changing the solenoid voltage (0 to 2kV), the magnetic field of the plasma itself is changed (the maximum magnetic field is in the range of 0 to 0.5T), thereby changing the terahertz wave pulse width (usually in the range of 1ns to 1μs).

[0035] See also Figure 1As shown, in this embodiment, eight gas injection windows 25 are evenly arranged on the outer circumference of the coaxial gun outer electrode 6, and a fast gas injection valve 4 is installed on each gas injection window 25. The fast gas injection valve 4 and the gas injection window 25 are fixed and pressed by a fluororubber sealing ring to form a vacuum isolation state. Energy is stored in a capacitor (capacitance value is in the range of 100μF to 1mF), and the coil of the load fast gas injection valve 4 is energized after the thyristor switch is turned on, driving the gas valve coil, generating electromagnetic force on the piston, thereby forming mechanical movement, and quickly injecting gas into the vacuum chamber between the coaxial gun inner electrode 5 and the coaxial gun outer electrode 6. The gas intake in the vacuum chamber is controlled by simultaneously adjusting the gas valve voltage (50V to 500V) and pulse width (100μs to 500μs) of the eight fast gas injection valves 4, thereby controlling the plasma density, and achieving a plasma density range of 1.24×10 20 m -3 to 1.24×10 24 m -3 .

[0036] See also Figure 3 As shown, in this embodiment, the end of the coaxial gun inner electrode 5 away from the diode insulating support 7 is fixedly connected to the inner electrode connection flange 8, and the end of the coaxial gun outer electrode 6 close to the inner electrode connection flange 8 is fixedly connected to the outer electrode connection flange 9. Sixteen coaxial cable inner electrode connection blocks 12 are installed on the outer periphery of the inner electrode connection flange 8 by screws to press the sixteen coaxial cable inner electrodes to form an electrical connection, and are electrically connected to the corresponding pulse power supply. Energy is stored through a capacitor (capacitance value is in the range of 10μF to 200μF), and is turned on through an ignition tube, a semiconductor switch or a gas switch, and a negative high voltage (-35kV to -5kV) is applied to the coaxial gun inner electrode 5, forming a strong electric field between the coaxial gun outer electrode 6, breaking down the neutral gas, and forming a plasma ring, wherein the plasma peak current is 50kA to 500kA, and the pulse width is 100μs to 300μs. The inner electrode connecting flange 8 is electrically insulated and vacuum isolated from the outer electrode connecting flange 9 through a ceramic insulating tube 10 and a polytetrafluoroethylene insulating tube 11. The inner electrode 5 of the coaxial gun is fixed and pressed to the diode insulating support 7 through a fluororubber sealing ring to form a vacuum isolation state and is electrically insulated from the diode anode 2.

[0037] See also Figure 3As shown, in this embodiment, the coaxial gun outer electrode 6 is welded to the outer electrode connection flange 9. Sixteen outer electrode adapter blocks 13 are mounted on the outer electrode connection flange 9 by screws, and are connected to the outer electrode extension flange 14 by screws. The outer electrode extension flange 14 and the coaxial cable outer electrode flange 16 are electrically connected to thirty-two electrical connection columns 15 by bolts. Sixteen coaxial cable outer electrode connection pressing blocks 18 are mounted on the coaxial cable outer electrode flange 16 by screws, and the sixteen coaxial cable outer electrodes are pressed to form an electrical connection, and are electrically connected to the corresponding pulse power supply. Thirty-two connection column insulating sleeves 17 are arranged on the thirty-two electrical connection columns 15. Two plasma diagnostic upper windows 19 are distributed on the coaxial gun outer electrode 6, which are used to measure the magnetic field of the magnetized plasma, using a two-dimensional magnetic probe (polar magnetic probe and circumferential magnetic probe). Four plasma diagnostic horizontal windows 20 are distributed on the coaxial gun outer electrode 6, which are used to measure the average density and radiation intensity of the magnetized plasma chord. The average density of the plasma string is measured by a 1550 nm wavelength laser fiber interferometer, and the radiation intensity is measured by a photoelectric converter, covering the optical wavelength range of 200 nm to 1100 nm. The coaxial gun outlet flange 21 is welded to the coaxial gun outer electrode 6. The support frame 22 is fixed to the coaxial gun outer electrode 6 by screws, and is fixed to the support platform 23 by screws. For the safety of the overall operation of the device, the coaxial gun outer electrode 6 is grounded.

[0038] Working principle of the present invention:

[0039] See also Figure 4 As shown in Figure 1, when a low-density electron beam is injected into a high-density plasma, the space charge force of the electron beam is very weak. At this time, the electrons of the plasma will be repelled by the electron beam, and then return to their original positions under the action of the restoring force, and finally rise to the plasma frequency ( ,in is the electron charge, is the plasma density, is the vacuum dielectric constant and The oscillation frequency of the electron mass forms plasma oscillation near the equilibrium position, which is called the plasma tail field. The plasma tail field modulates the electron beam to achieve positive feedback interaction. When the modulation reaches the nonlinear stage, the system will stimulate electromagnetic wave radiation near the plasma frequency and its multiples. When the plasma density is 1.24×10 20 m -3 to 1.24×10 24 m -3The plasma frequency is 0.1THz to 10THz, covering the entire terahertz band. The present invention generates a high-current relativistic electron beam through a vacuum diode and a magnetized coaxial gun to generate a magnetized plasma, forming a low-density electron beam that is injected into a high-density plasma to excite terahertz radiation with a frequency in the range of 0.1THz-10THz.

[0040] The terahertz radiation source is based on the mechanism of terahertz radiation excited by the interaction between the self-modulated electron beam and the plasma tail field, and its radiation frequency is near the plasma frequency and its frequency multiples. The invention scheme combines a high-current relativistic electron beam diode and a magnetized coaxial plasma gun to achieve high-efficiency energy conversion and high-power terahertz radiation. The high-current relativistic electron beam is driven on the diode by a pulse power supply and emitted by the diode cathode 1. The magnetized coaxial plasma gun consists of a solenoid coil 3, a fast gas injection valve 4 and a coaxial electrode, which are driven by corresponding pulse power supplies to generate a bias magnetic field, fast gas injection and magnetized plasma. The terahertz radiation source aims to solve the power limitation problem of radiation sources in the terahertz frequency band, provide a new technology solution for terahertz radiation sources, increase the frequency of electromagnetic wave radiation sources to the terahertz frequency band, and achieve high-efficiency and high-power radiation.

[0041] The above is a detailed description of the preferred embodiments of the present invention, which cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma, characterized in that: include: A magnetized coaxial plasma gun assembly, the magnetized coaxial plasma gun assembly comprising a solenoid coil (3), a fast gas injection valve (4), a coaxial gun inner electrode (5) and a coaxial gun outer electrode (6); A vacuum diode assembly, comprising a diode cathode (1) and a diode anode (2); The coaxial gun inner electrode (5) is located at one end of the coaxial gun outer electrode (6), and a vacuum chamber is formed between the coaxial gun inner electrode (5) and the coaxial gun outer electrode (6); a plurality of the rapid gas injection valves (4) are evenly arranged on the periphery of the coaxial gun outer electrode (6); the diode anode (2) is installed in the coaxial gun inner electrode (5) through a diode insulating support (7); the diode cathode (1) is arranged at one end of the diode anode (2) away from the diode insulating support (7); and the solenoid coil (3) is installed on the periphery of the diode anode (2) through a coil support (24).

2. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 1, characterized in that: An end of the coaxial gun inner electrode (5) away from the diode insulating support (7) is fixedly connected to an inner electrode connecting flange (8), and an end of the coaxial gun outer electrode (6) close to the inner electrode connecting flange (8) is fixedly connected to an outer electrode connecting flange (9), and the inner electrode connecting flange (8) and the outer electrode connecting flange (9) are fixedly connected via a ceramic insulating tube (10) and a polytetrafluoroethylene insulating tube (11).

3. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 2, characterized in that: A plurality of coaxial cable inner electrode connection pressing blocks (12) are evenly arranged on the outer periphery of the inner electrode connection flange (8).

4. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 2, characterized in that: A plurality of external electrode adapter blocks (13) are evenly arranged on the outer periphery of the external electrode connecting flange (9).

5. A terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 4, characterized in that: One end of the external electrode adapter block (13) away from the external electrode connecting flange (9) is fixedly connected to the external electrode extension flange (14).

6. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 5, characterized in that: The side of the outer electrode extension flange (14) away from the outer electrode adapter block (13) is fixedly connected to the coaxial cable outer electrode flange (16) via a plurality of electrical connection columns (15).

7. A terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 6, characterized in that: A plurality of connection column insulating sleeves (17) are also fixedly connected between the outer electrode extension flange (14) and the coaxial cable outer electrode flange (16), and one connection column insulating sleeve (17) is correspondingly provided for each electrical connection column (15).

8. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 7, characterized in that: A plurality of coaxial cable outer electrode connecting pressing blocks (18) are evenly arranged on the outer periphery of the coaxial cable outer electrode flange (16).

9. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 1, characterized in that: Two plasma diagnosis upper windows (19) are arranged on the periphery of the coaxial gun outer electrode (6), and the plasma diagnosis upper windows (19) are used for measuring the magnetic field of magnetized plasma.

10. The terahertz radiation source driven by an electron beam in a magnetized coaxial gun plasma according to claim 9, characterized in that: Four plasma diagnostic horizontal windows (20) are also arranged on the periphery of the coaxial gun outer electrode (6), and the plasma diagnostic horizontal windows (20) are used to measure the average density and radiation intensity of the magnetized plasma string.

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