CN109545638B

CN109545638B - Terahertz extension interaction oscillator with resonant cavity and cross structure

Info

Publication number: CN109545638B
Application number: CN201811381757.4A
Authority: CN
Inventors: 李爽; 滕雁; 王东阳
Original assignee: Northwest Institute of Nuclear Technology
Current assignee: Northwest Institute of Nuclear Technology
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2021-01-05
Anticipated expiration: 2038-11-20
Also published as: CN109545638A

Abstract

The invention provides a terahertz extension interaction oscillator with a resonant cavity and a cross structure, which is greatly different from the traditional terahertz extension interaction oscillator. In the conventional device, the longitudinal electric field concentration is distributed in a certain direction (e.g., x or y direction), while in the device of the cross structure, the longitudinal electric field is distributed in two directions (i.e., x and y directions) at the same time. Therefore, in the structure, the energy exchange efficiency of the longitudinal electric field and the cylindrical electron beam can be effectively enhanced, and the output power can be effectively improved. By optimally designing the cross-type extended interaction oscillator working at 0.3THz, the final device can realize the power output of about 51.5W under the working conditions of 14kV and 0.1A. The crossed structure is suitable for improving the output power of the terahertz expansion interaction oscillator, and is particularly suitable for improving the engineering realizability and the working stability of a device under lower working current.

Description

Terahertz extension interaction oscillator with resonant cavity and cross structure

Technical Field

The invention belongs to a design scheme of a high-performance Terahertz source, and particularly relates to a Terahertz source for improving Terahertz (1 THz-10)¹²Hz) extends the output power of the interacting oscillator and the feasible high frequency architecture.

Background

Terahertz (THz) waves refer to frequencies from 0.3THz to 3THz (1THz ═ 10)¹²Hz), electromagnetic waves between millimeter waves and infrared light, the last frequency band that has not been fully appreciated and utilized by humans. The terahertz wave is located in a transition region from a macroscopic classical theory to a microscopic quantum theory, and due to the special position of the terahertz wave, the radiation has the unique advantages of strong permeability, high resolution, non-ionization propagation, rich spectral characteristics and the like. These characteristics of terahertz wavesThe method has great application potential in the fields of information communication, medical diagnosis, biotechnology, material science, astronomy, military and the like, and draws high attention to all countries in the world. In the terahertz technology, a terahertz radiation source is the basis of terahertz application, but due to the influence of factors such as unstable working and low output power of most of the existing terahertz sources at present in a room temperature environment, the further development of terahertz science is greatly restricted, so that the development of the terahertz radiation source with stable performance and high output performance is the root of the development of the terahertz technology.

To date, the method of vacuum electronics is the most common means of generating high power terahertz radiation at room temperature. In vacuum electronic Devices, Extended Interaction Devices (EIDs) are an important class of generating Devices, which mainly include oscillators and amplifiers. Especially, the Extended Interaction Oscillator (EIO) is developed very rapidly, and the commercial EIO has been developed to the 220GHz band at present. The CPI company in Canada is the most advanced and experienced unit for developing EIO development technology in the world at present, and a 220GHz continuous wave EIO device produced by the CPI company can achieve power output of about 10W, specifically refer to www.cpii.com, and embodies higher design and processing level.

However, as the operating frequency continues to increase, the structural size of the device is greatly reduced, and the power capacity in the device is severely limited. Meanwhile, the beam wave interaction process puts higher requirements on the working current intensity, and even exceeds the working current capability which can be realized by the conventional electron gun.

Disclosure of Invention

In order to solve the problems of limited power capacity and poor realizability of an EIO device in a terahertz frequency band, the invention provides a terahertz extended interaction oscillator with a cross structure. The structure is particularly suitable for working under the condition of lower current, so that the realizability of the terahertz EIO device can be effectively improved.

Meanwhile, on the basis of the structure, the invention optimally designs the extension interaction oscillator working at 0.3THz, and the device can stably work. Under the electron beam condition of 14kV and 0.1A, the power output of about 51.5W can be obtained.

The technical scheme of the invention is to provide a resonant cavity, wherein the length direction of the resonant cavity is defined as Z direction, and the height direction of the resonant cavity is defined as Y direction; the resonant cavity comprises n gap units arranged along the Z direction;

it is characterized in that:

each gap unit is formed by vertically intersecting two identical dumbbell-shaped resonance gaps and comprises a cross-shaped re-entry part and four vacuum parts positioned at the end parts of the re-entry part;

4n vacuum parts and n reentrant parts form a vacuum chamber of the resonant cavity;

the centers of the n reentrant portions are provided with communicated electron beam channels.

Further, n is equal to 16.

Further, the width GWA of the vacuum portion of each gap unit is 0.7mm, and the width GWB of the reentrant portion end is 0.4 mm; the height GHA of the vacuum part is 0.35mm, and the height GHB of the re-entry part is 0.8 mm; the diameter D of the electron beam channel is 0.24 mm; the thickness GLA of the vacuum portion was 0.2mm, and the thickness GLB of the re-entry portion was 0.1 mm.

The invention also provides a terahertz extension interaction oscillator with a cross structure, which comprises a resonant cavity and an output waveguide arranged on the resonant cavity; defining the length direction of a resonant cavity as the Z direction and the height direction of the resonant cavity as the Y direction; the resonant cavity comprises n gap units arranged along the Z direction;

it is characterized in that:

the centers of the n reentrant parts are provided with communicated electron beam channels;

the output waveguide comprises a coupling hole, a transition section and a standard waveguide, wherein the XZ surface section size of the coupling hole is smaller than that of the standard waveguide, and the transition section is formed by directly and smoothly connecting the coupling hole and two adjacent surfaces of the standard waveguide; the coupling hole is coupled with the cavity of the resonant cavity vacuum chamber.

Further, the coupling hole and the standard waveguide are both rectangular waveguides.

Further, n is equal to 16.

Further, the width GWA of the vacuum portion of each gap unit is 0.7mm, and the width GWB of the reentrant portion end is 0.4 mm; the height GHA of the vacuum part is 0.35mm, and the height GHB of the re-entry part is 0.8 mm; the diameter D of the electron beam channel is 0.24 mm; the thickness GLA of the vacuum portion was 0.2mm, and the thickness GLB of the re-entry portion was 0.1 mm. Wherein the thickness direction is the Z direction.

Further, the width OCW of the coupling hole is 0.5mm, and the width OWW of the standard waveguide is 0.7 mm;

the length OCL of the coupling hole is 0.2mm, the height OCH of the coupling hole is 0.1mm, the length OWL of the standard waveguide is 0.35mm, the height OWH of the standard waveguide is 0.4mm, and the height OTH of the transition section is 1.0 mm.

Unlike the conventional EIO structure, the gap unit of the crossed EIO structure is formed by vertically crossing two gap structures. The pair of the longitudinal electric field distributions of the cross-type EIO and the conventional EIO in the cross section is shown in fig. 6a and 6 b. In the structure, the longitudinal electric field is uniformly distributed in the circumferential direction of the electron beam, so that the electron beam can be more fully modulated, and the working efficiency of the device can be effectively improved. The characteristic impedance of the cross type EIO versus the conventional EIO is shown in fig. 7 for the same gap size and the same number of gaps. It can be seen that by adopting the cross-type structure, the characteristic impedance of the whole structure is greatly improved, which is very advantageous for improving the beam interaction efficiency.

The invention has the beneficial effects that:

1. the output power of the terahertz EIO can be effectively improved. According to the cross-type high-frequency structure provided by the invention, the gap structures are arranged in the x and y directions of the cross section, the energy of a cylindrical electron beam is fully utilized, the beam wave interaction efficiency can be effectively increased, and the output power of a device is improved. In the EIO, the output power may reach about 51.5W.

2. The requirement for operating current can be reduced. Because the cross structure can effectively improve the beam wave interaction efficiency, the device can obtain higher output power under lower current. Since the requirements on the operating current can be reduced, the feasibility of producing electron guns is improved.

3. The device can stably operate. In the structure, the device can effectively work under lower current through optimizing working voltage and current, so that self-oscillation of a mixed mode is avoided, and stable operation of the device is ensured.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a cross-type extended interaction oscillator;

in the figure, 1-electron beam channel, 2-gap unit, 3-output waveguide;

FIG. 2 is a schematic cross-sectional view of a gap cell;

FIG. 3 is an isometric view of the gap cell;

FIG. 4 is a schematic cross-sectional view of an output waveguide;

in the figure: 4-coupling hole, 5-transition section, 6-standard waveguide;

FIG. 5 is a schematic longitudinal cross-sectional view of an output waveguide;

FIG. 6a is a longitudinal electric field distribution of a crossed EIO in cross-section;

FIG. 6b shows the longitudinal electric field distribution of a conventional EIO in cross-section;

FIG. 7 is a comparison of the characteristic impedance of a cross-type EIO and a conventional EIO;

FIG. 8a is the output power of a crossed EIO;

FIG. 8b is the output signal frequency of the crossed EIO;

FIG. 9 is a comparison of the output power of a cross-type EIO and a conventional EIO at different operating currents.

Detailed Description

The invention is further described with reference to the following figures and examples.

As can be seen from fig. 1, the cross-type extended interaction oscillator of the present embodiment is mainly composed of an

electron beam channel

1, 16 identical gap cells 2, and an output waveguide 3. The output waveguide 3 is coupled to one of the gap units 2, and the electron beam channel 1 passes through the center of the gap unit 2, so that the electron beam interacts with the gap electric field to output the waveguide 3. The direct current electron beam enters the electron beam channel 1, and generates beam wave interaction with the electric field at each gap unit 2, energy is transferred to the electromagnetic wave, and the generated terahertz wave is radiated out through the output waveguide 3. The electron gun uses ideal electron beam injection, the working voltage is 14kV, the working current is 0.1A, the guiding magnetic field uses a uniform magnetic field, and the intensity is 1.0T.

As can be seen from fig. 2 and 3, the gap unit of the present embodiment is formed by two identical dumbbell-shaped gap structures which are vertically crossed, and includes a cross-shaped re-entry portion and vacuum portions located at four ends of the re-entry portion, and the electron beam channel is disposed in the center of 16 re-entry portions; the width GWA of the vacuum portion of each gap cell is 0.7mm, and the width GWB of the reentrant portion end is 0.4 mm; the height GHA of the vacuum part is 0.35mm, and the height GHB of the re-entry part is 0.8 mm; the diameter D of the electron beam channel is 0.24 mm; the thickness GLA of the vacuum portion was 0.2mm, and the thickness GLB of the re-entry portion was 0.1 mm. The thickness direction here is the Z direction.

As can be seen from fig. 4 and 5, the entire output waveguide 3 of this embodiment is composed of three portions, i.e., a standard waveguide 6, a transition section 5 and a coupling hole 4, and the transition section 5 is formed by directly and smoothly connecting two adjacent surfaces of the coupling hole 4 and the standard waveguide 6. Wherein the width of the coupling hole OCW is 0.5mm and the width of the standard waveguide OWW is 0.7 mm. The length OCL of the coupling hole is 0.1mm, the height OCH of the coupling hole is 0.1mm, the length OWL of the standard waveguide is 0.35mm, the height OWH of the standard waveguide is 0.4mm, and the height OTH of the transition section is 1.0 mm.

Unlike the conventional EIO structure, the gap unit of the crossed EIO structure is formed by vertically crossing two gap structures. The pair of the longitudinal electric field distributions of the cross-type EIO and the conventional EIO in the cross section is shown in fig. 6a and 6 b. It can be seen that in the cross type EIO structure, the longitudinal electric field is distributed in the direction around the electron beam, so that the electron beam can be modulated more fully, and the working efficiency of the device can be effectively improved. In the conventional EIO structure, the longitudinal electric field is applied to the electron beam only in the vertical direction. The characteristic impedance of the cross type EIO versus the conventional EIO is shown in fig. 7 for the same gap size and the same number of gaps. It can be seen that the characteristic impedance of the cross-type EIO is about 2-3 times that of the conventional EIO, and thus the beam interaction efficiency can be greatly improved in the cross-type EIO.

The basic working process is as follows:

the 0.3THz extension interaction oscillator adopting the cross structure is taken as an embodiment of the invention, and the working conditions of the device are that the electron beam intensity is 0.1A and the voltage is 14 kV.

Under the guidance of a uniform magnetic field of 1.0T, the cylindrical electron beams enter the high-frequency structure through the electron beam channel, and are continuously modulated by the gap electric field at the gap unit, and finally, a cluster is formed. Meanwhile, the clustered electron beams and longitudinal electric fields uniformly distributed in the circumferential direction of the clustered electron beams have strong interaction, and energy is transferred to electromagnetic waves, so that the energy of the electromagnetic waves is effectively amplified and radiated outwards along the output coupling holes. The calculation results of UNIPIC software are shown in fig. 8a and 8b, and it can be seen that the output power of the device is about 51.5W and the operating frequency is 318.54GHz under the structure. The device has stable working state. The comparison of the output power of the cross-type EIO and the conventional EIO under different operating current conditions is shown in fig. 9, and it can be seen that the output power of the cross-type EIO in this embodiment is much higher than that of the conventional EIO structure. Moreover, the output power advantage of the crossed EIO is more enhanced at low current conditions.

The cross-type high-frequency structure can not only improve the output power of the EIO device, but also enable the device to effectively work under lower current. The method can effectively improve the output performance of the device and greatly improve the engineering feasibility of the device.

Claims

1. A resonant cavity is defined, the length direction of the resonant cavity is the Z direction, and the height direction of the resonant cavity is the Y direction; the resonant cavity comprises n gap units arranged along the Z direction;

the method is characterized in that:

2. The resonant cavity of claim 1, wherein: n is equal to 16.

3. The resonant cavity of claim 2, wherein: the width GWA of the vacuum portion of each gap cell is 0.7mm, and the width GWB of the reentrant portion end is 0.4 mm; the height GHA of the vacuum part is 0.35mm, and the height GHB of the re-entry part is 0.8 mm; the diameter D of the electron beam channel is 0.24 mm; the thickness GLA of the vacuum portion was 0.2mm, and the thickness GLB of the re-entry portion was 0.1 mm.

4. A terahertz extension interaction oscillator with a cross structure comprises a resonant cavity and an output waveguide arranged on the resonant cavity; defining the length direction of a resonant cavity as the Z direction and the height direction of the resonant cavity as the Y direction; the resonant cavity comprises n gap units arranged along the Z direction;

the method is characterized in that:

the output waveguide comprises a coupling hole, a transition section and a standard waveguide, the cross section size of an XZ surface of the coupling hole is smaller than that of the XZ surface of the standard waveguide, and the transition section is formed by directly and smoothly connecting the coupling hole and two adjacent surfaces of the standard waveguide; the coupling hole is coupled with the cavity of the resonant cavity vacuum chamber.

5. The terahertz extension interaction oscillator of a cross structure of claim 4, wherein: the coupling hole and the standard waveguide are both rectangular waveguides.

6. The terahertz extension interaction oscillator of a cross structure of claim 4, wherein: n is equal to 16.

7. The terahertz extension interaction oscillator of a cross structure of claim 6, wherein: the width GWA of the vacuum portion of each gap cell is 0.7mm, and the width GWB of the reentrant portion end is 0.4 mm; the height GHA of the vacuum part is 0.35mm, and the height GHB of the re-entry part is 0.8 mm; the diameter D of the electron beam channel is 0.24 mm; the thickness GLA of the vacuum portion was 0.2mm, and the thickness GLB of the re-entry portion was 0.1 mm.

8. The terahertz extension interaction oscillator of a cross structure of claim 6, wherein: the width OCW of the coupling hole is 0.5mm, and the width OWW of the standard waveguide is 0.7 mm;