阅读说明：本技术 一种小型化高耦合阻抗的互补开口谐振环慢波结构 (Miniaturized high-coupling-impedance complementary split resonant ring slow-wave structure ) 是由 段兆云 王新 罗恒宇 张宣明 江胜坤 王战亮 巩华荣 宫玉彬 于 2019-08-26 设计创作，主要内容包括：本发明公开了一种小型化高耦合阻抗的互补开口谐振环慢波结构,属于真空微波电子、加速器和切伦科夫粒子探测器等技术领域。该慢波结构包括金属圆波导和其内部沿轴线填充的CSRR单元阵列,其中互补开口谐振环具有较强的谐振特性,可以通过改变互补开口谐振环的横向尺寸实现任意的工作频率。本发明的慢波结构与同频段(S波段)的传统慢波结构相比,其横截面积只有同频段传统耦合腔慢波结构的1/8～1/9,而耦合阻抗为S波段传统耦合腔慢波结构的2～4倍。由于该慢波结构具有小型化和高耦合阻抗的特点,故本发明能够应用于小型化、高效率和高功率的线性注真空电子器件、加速器和切伦科夫粒子探测器等领域当中。(The invention discloses a miniaturized high-coupling-impedance complementary split resonant ring slow-wave structure, and belongs to the technical fields of vacuum microwave electrons, accelerators, Cerenkov particle detectors and the like. The slow wave structure comprises a metal circular waveguide and a CSRR unit array filled in the metal circular waveguide along the axis, wherein the complementary split resonant ring has strong resonance characteristics, and any working frequency can be realized by changing the transverse dimension of the complementary split resonant ring. Compared with the traditional slow wave structure of the same frequency band (S wave band), the slow wave structure has the cross section area of 1/8-1/9 of the traditional coupling cavity slow wave structure of the same frequency band, and the coupling impedance is 2-4 times of that of the traditional coupling cavity slow wave structure of the S wave band. The slow wave structure has the characteristics of miniaturization and high coupling impedance, so the invention can be applied to the fields of miniaturization, high-efficiency and high-power linear beam vacuum electronic devices, accelerators, Cerenkov particle detectors and the like.)

1. A miniaturized high-coupling-impedance complementary split ring slow-wave structure is characterized by comprising a metal circular waveguide 7 and a CSRR unit array filled with the metal circular waveguide along the axis;

the CSRR unit array comprises N CSRR units which are periodically arranged, wherein N is a positive integer; the CSRR unit comprises a circular metal inner ring 2, a middle split ring 3 and a circular metal outer ring 4 which are concentrically arranged from inside to outside, and an electron beam channel is arranged in the middle of the metal inner ring 2; a first metal bridge 1 is connected between the metal inner ring 2 and the metal outer ring 4, and a second metal bridge 5 is connected between the middle split ring 3 and the metal outer ring 4; the outer side of the metal outer ring 4 is tightly attached to the circular waveguide 7; the first metal bridge 1 and the second metal bridge 5 are located on the same diameter.

2. The miniaturized high-coupling-impedance complementary split-ring slow-wave structure as claimed in claim 1, wherein the number of split rings in the middle of the CSRR unit is increased or decreased according to the target frequency; when the number of the middle opening rings is more than or equal to 2, the opening positions of two adjacent middle opening rings rotate 180 degrees.

3. A miniaturized high-coupling-impedance complementary split-ring slow-wave structure as claimed in claim 1, wherein the size of the split of said intermediate split ring 3 is adjusted for adjusting the operating frequency of the slow-wave structure.

4. The miniaturized high-coupling-impedance complementary split ring resonator slow-wave structure of claim 1, wherein the inner side of the metal inner ring 2 is further provided with closely attached inner drift tubes, and a gap is formed between two adjacent inner drift tubes.

Technical Field

The invention belongs to the technical field of vacuum microwave electronic devices, accelerators, Cerenkov particle detectors and the like, and particularly relates to a complementary open resonant ring slow-wave structure with miniaturization and high coupling impedance.

Background

Vacuum electronic devices have become core devices in the fields of accelerators, microwave heating, communications, radar, electronic warfare, and high power microwave weapons due to their unique power, efficiency, bandwidth, and gain advantages. The traveling wave tube is widely applied to the aspects of aerospace, medical treatment, industry, particle detection technology and the like as a most widely applied vacuum electronic device. The slow-wave structure is used as the core part of the traveling wave tube, and the characteristics of the slow-wave structure directly determine the overall performance of the traveling wave tube, including working bandwidth, electronic efficiency, gain, output power and the like. The traditional helix slow wave structure and the coupled cavity slow wave structure are widely applied to various traveling-wave tubes and have advantages in bandwidth and power capacity. However, with the continuous development of scientific technology, especially the high-speed development of semiconductor devices, besides the traditional target parameters of bandwidth, power, efficiency and gain, the miniaturization and easy integration of the structure are becoming an important index of vacuum electronic devices. Vacuum electronic devices based on conventional slow-wave structures are subject to size sharing effects and specific mode distributions in the structures in terms of miniaturization and electronic efficiency, and face a great challenge in the direction of mutual integration with semiconductor devices.

The size of conventional vacuum electronic devices is limited by the size-sharing effect, which is approximately half a wavelength in lateral diameter or length. Taking a typical S-band 3GHz coupled cavity traveling wave tube as an example, the radius of a coupled cavity is about 22mm, and the wavelength diameter ratio lambda/D (a quantity for representing the transverse dimension of the device, the larger the ratio is, the more obvious the miniaturization of the device is) is 2.27; on the other hand, the coupled cavity traveling wave tube has a narrow bandwidth and relatively high coupling impedance relative to the spiral line traveling wave tube, so that the coupled cavity traveling wave tube has high electronic efficiency and output power in the wave injection interaction process. Even so, the coupling impedance of the cavity traveling wave tube does not exceed 1000 Ω (typical value is 300-500 Ω) (V.L. Christie, L.Kumar, and N.Balakrishnan, "Improved equivalent impedance model of reactive narrow-wave structures for TWTs," micro.Opt. technol. Lett., vol.35, No.4, pp.322-326,2002.). In 2014, an invention patent (segment megacloud, king comma, yellow auspicious, and the like, a small all-metal slow-wave device, application number: 201410280414) of electronic science realizes an all-metal slow-wave device in an S wave band, the transverse dimension of the all-metal slow-wave device is 1/2-1/3 of a traditional coupling cavity traveling wave tube, the coupling impedance is about 1200 ohms, and compared with a traditional coupling cavity slow-wave structure, the all-metal slow-wave device has certain advantages in the aspects of the transverse dimension and the coupling impedance. Compared with the traditional coupling cavity slow-wave structure, the novel coupling cavity slow-wave structure has the advantages that the miniaturization is extremely obvious in size (the cross section area is 1/9 of the S-band traditional coupling cavity slow-wave structure), and the coupling impedance is higher (more than 1900 ohms and 2-4 times of that of the S-band traditional coupling cavity slow-wave structure). The advantages of miniaturization and high coupling impedance of the present invention are very prominent even when compared with the all-metal miniaturized slow wave structure at the present stage.

In order to realize the miniaturization of the device, one of the key factors is to realize the miniaturization of the slow-wave structure, and for the same type of coupled cavity slow-wave structure, the coupling impedance of the slow-wave structure is not reduced, i.e. higher coupling impedance is obtained on the basis of miniaturization, so that the electric vacuum device based on the slow-wave structure has the advantages of more compact structure, higher electronic efficiency and high power. An important solution is to abandon the traditional slow wave structure and adopt a new idea to design the slow wave structure. It has been found that the fundamental mode resonance frequency of the Complementary Split Ring Resonator (CSRR) depends mainly on the distribution path of its internal high frequency current, regardless of the lateral dimensions of the externally loaded waveguide. That is, theoretically, the slow-wave structure working in any frequency band can be designed by changing the path of the high-frequency current on the CSRR. The slow wave structure of the complementary split ring resonator provided by the invention is characterized in that: 1) a brand-new extremely miniaturized CSRR unit structure is designed; 2) the complementary split resonant ring slow-wave structure composed of the CSRR units and the circular waveguide has the characteristics of miniaturization (lambda/D is 6.6) and high coupling impedance (more than 1900 omega in the whole dispersion passband), and the characteristic is remarkably superior to that of the conventional slow-wave structure; 3) a section of drift tube can be loaded on the outer side of an electron beam channel of the complementary split resonant ring slow-wave structure to adjust the working frequency, the bandwidth and the phase velocity of electromagnetic waves; 4) the 0 th spatial harmonic of the slow wave structure is a forward wave and can propagate a slow electromagnetic wave.

Disclosure of Invention

The object of the present invention is to solve the problem of the size of the slow wave structure in the prior art and to improve the coupling impedance thereof. The invention creatively fills the CSRR unit array in the metal circular waveguide, and provides a miniaturized and high-coupling-impedance slow wave structure which can be applied to a linear microwave injection vacuum electronic device, an accelerator and a Cerenkov particle detector.

The technical scheme adopted by the invention is as follows:

a miniaturized high-coupling-impedance complementary split-ring slow-wave structure comprises a metal circular waveguide 7 and a CSRR unit array filled in the metal circular waveguide along the axis.

The CSRR unit array comprises N CSRR units which are periodically arranged, wherein N is a positive integer; the CSRR unit comprises a circular metal inner ring 2, a middle split ring 3 and a circular metal outer ring 4 which are concentrically arranged from inside to outside, and an electron beam channel is arranged in the middle of the metal inner ring 2; a first metal bridge 1 is connected between the metal inner ring 2 and the metal outer ring 4, and a second metal bridge 5 is connected between the middle split ring 3 and the metal outer ring 4; the outer side of the metal outer ring 4 is tightly attached to the circular waveguide 7; the first metal bridge 1 and the second metal bridge 5 are located on the same diameter.

The number of split rings of the CSRR unit may be increased or decreased as required by the target frequency. When the number of the middle opening rings is more than or equal to 2, the opening positions of two adjacent middle opening rings rotate 180 degrees.

Further, the size of the opening of the intermediate open ring 3 can be adjusted to adjust the working frequency of the slow wave structure.

Furthermore, the inner side of the metal inner ring 2 is also provided with closely attached inner drift tubes, and a gap is arranged between every two adjacent inner drift tubes for expanding the bandwidth of the slow wave structure.

Compared with the conventional coupled cavity slow wave structure, the complementary split ring resonator slow wave structure provided by the invention is composed of the CSRR unit array and the metal circular waveguide, and has obvious difference with the conventional coupled cavity slow wave structure. According to the invention, the CSRR unit array is loaded in the circular waveguide, so that the transverse size of the slow wave structure can be reduced at will theoretically.

The invention has the beneficial effects that: according to the invention, the CSRR unit array is introduced into the circular waveguide, so that the problem of large transverse size of the traditional slow wave structure is solved, and the weight and the volume of the slow wave structure are reduced; and the complementary split-ring slow-wave structure has the characteristic of higher coupling impedance, so that the electric vacuum device based on the slow-wave structure has higher electronic efficiency. Further, the bandwidth of the slow wave structure can be expanded by adding a section of inner drift tube on the inner metal ring of the CSRR unit. The complementary open resonant ring slow-wave structure has wide application prospect in developing high-efficiency and miniaturized vacuum electronic devices, accelerators and Cerenkov particle detectors.

Drawings

Fig. 1 is a schematic diagram of a complementary split ring resonator slow-wave structure according to the present invention, wherein (a) is a front view structural diagram of a CSRR unit having 1 split ring; (b) is a cross-sectional view of the overall slow-wave structure of the embodiment;

FIG. 2 is a schematic diagram of high-frequency current distribution on a CSRR cell structure according to an embodiment;

FIG. 3 is an axial electric field profile of a periodic slow wave structure of an embodiment;

FIG. 4 is a graph of simulated dispersion curves for the slow wave structure of an embodiment;

FIG. 5 is a graph of coupling impedance of an embodiment;

FIG. 6 is a graph of normalized phase velocity for an embodiment;

fig. 7 is an extended structure of the CSRR cell of the embodiment, wherein (a) is a schematic structural view of the CSRR cell with an internal drift tube; (b) CSRR units with 0 split rings, (c) CSRR units with 2 split rings.

Detailed Description

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

The present embodiment provides a miniaturized, high-coupling-impedance complementary split-ring slow-wave structure, and its structural schematic diagram is shown in fig. 1, in which (a) is a structural schematic diagram of a CSRR unit, and (b) is an overall structural schematic diagram of a complementary split-ring slow-wave structure (including a split-ring in the middle and without an internal drift tube).

The slow wave structure of the embodiment is composed of a metal circular waveguide 7 and N CSRR unit structures filled in the metal circular waveguide, each CSRR unit comprises a circular metal inner ring 2, a middle open ring 3 and a circular metal outer ring 4 which are concentrically arranged from inside to outside, and an electron beam channel is arranged in the middle of the metal inner ring 2; a first metal bridge 1 is connected between the metal inner ring 2 and the metal outer ring 4, and a second metal bridge 5 is connected between the middle split ring 3 and the metal outer ring 4; the outer side of the metal outer ring 4 is tightly attached to the circular waveguide 7; the first metal bridge 1 and the second metal bridge 5 are located on the same diameter. As shown in fig. 1, in the present embodiment, the CSRR cell structure size is: the radius r1 of the electron beam channel 6 of the CSRR unit is 2mm, and the width w1 of the circular metal inner ring 2 is 1.5 mm; the inner diameter r2 of the intermediate split ring 3 is 4.5mm, and the width w2 of the intermediate split ring 3 is 1 mm; the inner diameter r3 of the circular metal outer ring 4 is 6.5mm, and the width w3 of the circular metal outer ring 4 is 1 mm; the width t of the first metal bridge 1 and the second metal bridge 5 are both 1 mm. The diameter D of the circular waveguide of the slow wave structure is 15mm, the period length p of the slow wave structure is 14mm, and the thickness h of the CSRR unit is 1 mm.

Based on the parameters of the CSRR unit and the slow-wave structure of the structure of fig. 1, the distribution of the high-frequency current on the CSRR unit is obtained through the eigen-mode simulation of the unit period as shown in fig. 2, and it can be seen that the path of the high-frequency current is distributed along the inner ring, the middle ring and the outer ring of the CSRR unit, which indicates that the metal ring of the CSRR unit can be changed arbitrarily to change the path of the high-frequency current, thereby changing the operating frequency of the slow-wave structure, i.e., the operating frequency range can be adjusted arbitrarily by changing the structure of; the field distribution of the eigenmode of the corresponding unit period is shown in fig. 3, and the field distribution corresponding to the fundamental mode (the first mode) can be found to be a quasi-TM mode, which has a strong axial electric field, indicating that the slow-wave structure has a high coupling impedance. The dispersion corresponding to the fundamental mode is shown in fig. 4, and it can be found that the dispersion band of the slow-wave structure of the embodiment is 3.075GHz-3.192GHz when the period length p of the slow-wave structure is 14mm and the inner diameter D of the slow-wave structure is 15 mm; coupling impedance curves as shown in fig. 5, the coupling impedance is greater than 1900 ohms throughout the dispersion band. The cross section area of the complementary split ring slow-wave structure provided by the invention is 1/8-1/9 of the traditional coupling cavity slow-wave structure, and the coupling impedance is 2-4 times of the traditional coupling cavity slow-wave structure. Further obtaining the normalized phase velocity vp/c (where vp is the phase velocity of the electromagnetic wave, and c is the optical velocity of free space) as shown in fig. 6, it can be found that the phase velocity of the 0 th spatial harmonic of the slow wave structure is smaller than the optical velocity. Further, on the basis of the CSRR unit of the embodiment, by providing a closely attached inner drift tube inside the inner metal ring, as shown in fig. 7(a), the operating bandwidth can be extended; by reducing the number of the intermediate split rings, as shown in fig. 7(b), or increasing the number of the intermediate split rings, as shown in fig. 7(c), the operating frequency can be adjusted, so that the complementary split resonant ring slow-wave structure can operate at any target frequency.

In summary, the complementary split-ring slow-wave structure provided by the invention has the characteristics of miniaturization and high coupling impedance, has potential advantages of miniaturization, high electronic efficiency and high power for vacuum electronic devices developed by using the complementary split-ring slow-wave structure, and especially has an important application value for developing low-frequency-band, narrow-band and high-power traveling wave tubes. Meanwhile, according to the requirement of the target frequency, the working frequency band of the slow-wave structure can be adjusted to the target working frequency by changing the number of the middle open rings and the sizes of the openings of the CSRR units; an internal drift tube can be loaded on an inner ring of the CSRR unit according to the requirement of a design target on the working bandwidth, so that the working bandwidth of the CSRR unit is expanded; and for the requirements of different target powers, the dispersion curve of the slow wave structure can be adjusted by adjusting the period length of the slow wave structure, so that the slow wave structure has different normalized phase speeds, namely different electron beam voltages, and the output power of the device is adjusted. In addition, the slow wave structure provided by the invention is beneficial to developing a traveling wave tube because the 0 th spatial harmonic of the dispersion curve of the fundamental wave is a forward wave, however, the slow wave structure can work in a backward wave area by utilizing the-1 st spatial harmonic or a higher-order mode, so that the backward wave tube with a miniaturized structure is developed. The complementary open resonant ring slow-wave structure provides a new design idea for developing high-performance vacuum electronic devices, accelerators, Cerenkov particle detectors and the like.