CN102956415A - Ray representation method of gyrotron quasi-optical output system - Google Patents

Abstract

The invention discloses a ray representation method of a gyrotron quasi-optical output system, and relates to the microwave technology. The method comprises the following steps of: a) determining an incident light angle; b) selecting the curved surface shape of two mirror reflectors; c) orderly placing the first mirror reflector and the second mirror reflector on an output light path of a gyrotron radiator; d) converting the propagation characteristics of a millimeter wave beam on the first mirror reflector and the second mirror reflector into a light propagation process of a light ray on the first mirror reflector and the second mirror reflector; e) charting the reflected propagation path of the light ray in a first mirror reflector and second mirror reflector conversion system; f) according to the propagation path chart formed in the step e), guiding design and rectification of the curved surface of the reflector of a quasi-optical mode converter, and finishing. The representation method provided by the invention is accurate, simple, practical and low in cost.

Description

A Ray Representation Method of Quasi-light Output System of Gyrotron

technical field

The invention relates to microwave technology, in particular to a high-power gyrotron millimeter-wave source, and is a ray representation of a gyrotron quasi-light output system. the

Background technique

Gyrotron is a kind of fast-wave device developed based on the mechanism of electron gyrotron maser. Its working mechanism can be understood as using the change of gyrotron frequency of electrons in the magnetic field and the grouping of electrons through the relativistic effect to make electrons interact with synchronous electromagnetic waves. role, excited to produce high-energy microwave radiation. The structure of the gyrotron is relatively simple, and it can generate high pulse peak power and continuous wave power in various ways in the millimeter and submillimeter wave bands, filling the gap of traditional microwave tubes and lasers in this wave band. At present, gyrotrons have been widely used in plasma heating of controlled thermonuclear fusion, high-energy particle accelerators, millimeter-wave directed energy weapons, material processing, and plasma chemistry. the

With the development of gyrotrons towards high frequency and high power, most of their working modes adopt low-loss high-order cavity modes, and the most typical working modes are TE _0n angular symmetric mode, TE _mn side gallery mode (m>>n and n=1 or 2) and TE _mn asymmetric phantoms (m>>1 and n>2). Due to the serious diffraction and polarization loss of the high-order mode in the cavity during transmission, it is actually not suitable for the transmission in free space. The high-order mode in the cavity must be converted into a low-order waveguide mode or free space that is convenient for transmission. Gaussian beam. In order to directly convert the complex field structure of the high-order working mode in the gyrotron into a linearly polarized Gaussian beam, it can be realized by a quasi-optical mode converter. In general, a quasi-optical mode converter is composed of an electrically large waveguide radiator with an open end and two curved mirror systems (as shown in Figure 1). In Figure 1, the mark 1 is the cavity, the mark 2 is the radiator, the mark 3 is the first specular reflector, the mark 4 is the second specular reflector, the mark 5 is the output window, the mark 6 is the microwave beam, and the mark 7 is the electron beam . For millimeter waves or submillimeter waves, the quasi-optical mode converter is electrically large in both horizontal and vertical dimensions. When high-frequency simulation software is used to perform full three-dimensional high-frequency simulation calculations on the quasi-optical mode converter It is difficult to effectively and quickly guide the design work of quasi-optical mode converters when huge computing resources and computers are required.

Contents of the invention

The purpose of the invention is to disclose a ray representation method of a quasi-light output system of a gyrotron to solve the problems in the prior art. the

For achieving the above object, technical solution of the present invention is:

A ray representation of a gyrotron quasi-light output system, which comprises the steps of:

a) Determine the incident light angle;

b) Select the curved surface shape of the two specular reflectors;

c) placing the first specular reflector and the second specular reflector on the output light path of the gyrotron radiator in sequence;

d) According to the principle that the millimeter wave beam generated from the gyrotron radiator is equivalent to the light ray, the propagation characteristics of the millimeter wave beam on the first specular reflector and the second specular reflector are equivalent to the light ray passing through the first specular reflector and the light propagation process on the second specular reflector;

e) According to the law of optical reflection and using CAD drawing tool software, the reflection propagation path of the light ray in the conversion system of the first specular reflector and the second specular reflector is clearly expressed;

f) According to the propagation path diagram in step e), understand and grasp the propagation path of the millimeter wave beam in the entire conversion system, if it meets the requirements, guide the design of the quasi-optical mode converter mirror surface and surface correction, and complete. the

The curved surface shape of the specular reflector in the step b) is a paraboloid, a cylinder, an ellipsoid, a sphere or a hyperboloid. the

The ray representation of the quasi-light output system of the gyrotron, in the step f), if the step

If the propagation path diagram in e) does not meet the requirements, return to step b) and proceed again. the

The ray representation of the gyrotron quasi-optical output system is used to represent the application ray of the gyrotron quasi-optical output system, the application ray of the gyrotron quasi-optical resonant cavity or the application ray of optical devices. the

The representation method of the invention is accurate, simple, practical and low in cost, and can guide the design and correction of the curved surface of the reflector of the quasi-light mode converter. the

Description of drawings

Figure 1 is a gyrotron with a built-in quasi-optical mode converter;

Figure 2a-Figure 2e is a parabolic mirror reflector, used to demonstrate the step-by-step implementation process of the ray representation of the gyrotron quasi-light output system on the mirror reflector; where:

Figure 2a is a parabolic specular reflector generated by CAD drawing software;

Fig. 2b has provided a bundle of light rays sent by the light source (placed on the focus O position) of the parabolic specular reflector;

Fig. 2c is that there is a plane passing through the vertex of the light ray and the parabolic specular reflector, and there is an intersection line between the plane and the parabolic specular reflector, and the intersecting line is a parabolic curve; the point a is used as the datum plane, and the datum plane is perpendicular to the parabolic curve;

Figure 2d takes the datum plane as a symmetrical plane, and makes a mirror image of the light ray to form a reflected ray, and thus completes a reflection process of the light emitted by the light source (point O) on the parabolic mirror reflector;

Figure 2e is another five light rays (marked as 11-15 respectively) and their corresponding reflected rays;

Fig. 3 is a ray representation flow chart of a gyrotron quasi-light output system of the present invention. the

Labels in the figure:

Cavity-1 Radiator-2 First specular reflector-3

Second Specular Reflector-4 Output Window-5 Microwave Beam-6

Electron Beam-7 Light Ray-8 Reflected Light Ray-8a

Intersection line-9 Datum plane-10

Five Rays of Light - 11, 12, 13, 14, 15

Five reflected rays - 11a, 12a, 13a, 14a, 15a. 

Detailed ways

A ray representation method of a gyrotron quasi-light output system of the present invention is based on the ray-like characteristics of millimeter waves or submillimeter waves, the millimeter wave beam generated from the gyrotron radiator is equivalent to an optical ray, and the millimeter wave beam is first The propagation characteristics on the first specular reflector and the second specular reflector are equivalent to the ray propagation process of light rays on the first specular reflector and the second specular reflector; according to the law of optical reflection and by means of CAD drawing tool software, the The reflection propagation path of the light ray in the conversion system of the first specular reflector and the second specular reflector is clearly expressed, so as to understand and grasp the propagation path of the millimeter wave beam in the entire conversion system to guide the optical mode converter Design and surface modification of mirror surfaces. the

Embodiments of the present invention will be described below with reference to the accompanying drawings. the

Figure 1 is a gyrotron with a built-in quasi-optical mode converter. The quasi-optical mode converter includes a radiator and two specular reflectors (the number of specular reflectors is related to the conversion quality and mode conversion efficiency of the Gaussian beam at the output window). In the gyrotron interaction cavity, the high-order working mode interacts with the cyclotron beam to generate high-power millimeter waves. The millimeter waves are radiated by the radiator and adjusted by the reflection of the mirror reflector 3 and the mirror reflector 4 successively. The distribution of high-order modes The millimeter wave is converted into a Gaussian distributed millimeter wave, and finally sent out through the output window. the

According to the light-like characteristics of the millimeter wave or submillimeter wave, the propagation characteristics of the millimeter wave beam generated from the radiator on the conversion system composed of the specular reflector 3 and the specular reflector 4 are equivalent to the light rays of the light rays on the conversion system Propagation process: According to the law of optical reflection and with the help of CAD drawing tools, the reflection propagation path of light rays in the conversion system can be clearly expressed, so as to understand and master the propagation characteristics of the millimeter wave beam in the entire conversion system. the

In order to illustrate the implementation process of the ray representation of the quasi-light output system of the gyrotron, the propagation process of the light ray is demonstrated by taking a specular reflector as a parabolic surface as an example. In order to clearly describe the process of light ray formation and its drawing description, each step and each figure are used to illustrate. Figures 2a-2e show the reflection and drawing process of the light rays emitted by the light source (placed at the focal point O) on the parabolic mirror reflector according to the law of optical reflection and by means of CAD drawing tools. Figure 2a is a parabolic specular reflector generated by CAD drawing software. Fig. 2b shows a beam of light rays 8 emitted by the light source (placed at the focal point O) of the parabolic specular reflector, and the light ray 8 intersects the parabolic specular reflector at point a. There is a plane through the vertex of the light ray 8 and the parabolic specular reflector, and there is an intersection line 9 between the plane and the parabolic specular reflector, and the intersecting line 9 is a parabolic curve; the point a is used as the datum plane 10, and the datum plane 10 is perpendicular to the parabolic curve 9, as shown in Figure 2c. Taking the reference plane 10 as the symmetry plane, making the mirror image of the light ray 8, the reflected light 8a is formed. So far, the first reflection process of the light emitted by the light source (point O) on the parabolic mirror reflector is completed, as shown in Figure 2d. Similarly, another five light rays (marked as 11-15 respectively) and their corresponding reflected rays (marked as 11a-15a respectively) can be made, as shown in FIG. 2e. It can be seen from the figure that since the light source is placed at the focal point of the parabolic mirror reflector, the reflected light rays (number: 11a-15a) are parallel to each other, that is to say, the light emitted from the focal point is the outgoing light after being reflected by the parabolic mirror reflector It is a parallel light, which also verifies the correctness of the drawing method and process. In Fig. 2a-Fig. 2e, although the incident light is emitted by the focal point, in the actual quasi-light mode changer, the incident light of the specular reflector is the incident light at a specific angle (the angle is determined by the radiator), but the light is on the mirror surface The reflection on the reflector and its drawing process are exactly the same as those in Figure 2a-2e. The light reflected by the specular reflector is the incident light on the next-level specular reflector, and its reflection and drawing process are still the same, so the 2a-Fig. 2e completely describe the ray representation of the quasi-light output system of the gyrotron. the

A ray representation method of a quasi-light output system of a gyrotron according to the present invention, the process flow is shown in FIG. 3 . Include steps:

a) Determine the incident light angle;

b) Select the curved surface shape of the two specular reflectors, the curved surface shape is a paraboloid, a cylinder, an ellipsoid, a sphere or a hyperboloid;

c) placing the first specular reflector and the second specular reflector on the output light path of the gyrotron radiator in sequence;

d) According to the principle that the millimeter wave beam generated from the gyrotron radiator is equivalent to the light ray, the propagation characteristics of the millimeter wave beam on the first specular reflector and the second specular reflector are equivalent to the light ray passing through the first specular reflector and the light propagation process on the second specular reflector;

e) According to the law of optical reflection and using CAD drawing tool software, the reflection propagation path of the light ray in the conversion system of the first specular reflector and the second specular reflector is clearly expressed;

f) According to the propagation path diagram in step e), understand and grasp the propagation path of the millimeter wave beam in the entire conversion system, if it meets the requirements, that is to guide the design of the quasi-optical mode converter mirror surface and surface correction, and complete;

If the requirements are not met, return to step b) and proceed again. the

Claims (4)

1. the ray representation of the quasi-optical output system of gyrotron is characterized in that, comprises step:

A) determine angle of incident light;

B) curve form of selection two specular reflectors;

C) the first specular reflector, the second specular reflector sequentially are positioned on the output light path of gyrotron radiator;

D) according to the millimeter wave beam that produces from the gyrotron radiator and the principle of light ray equivalence, be the light transmition process of light ray on the first specular reflector and the second specular reflector with millimeter wave beam in the equivalence of the propagation characteristic on the first specular reflector and the second specular reflector;

E) according to the optical reflection law and with CAD drafting instrument software, with the reflected propagation paths drawing of light ray in the first specular reflector and the second specular reflector converting system, clearly express;

F) according to step e) propagation path figure, understand and grasp the propagation path of millimeter wave beam in whole converting system, if meet the requirements, namely instruct design and the curved surface correction of quasi-Optical Mode Converter curved surface of reflector, finish.

2. the ray representation of the quasi-optical output system of gyrotron as claimed in claim 1 is characterized in that, described step b) in the curve form of specular reflector be parabola, cylinder, ellipsoid, sphere or hyperboloid.

3. the ray representation of the quasi-optical output system of gyrotron as claimed in claim 1 is characterized in that, described step f) in, if step e) propagation path figure undesirable, return step b), re-start.

4. the ray representation of the quasi-optical output system of gyrotron as claimed in claim 1, it is characterized in that, the ray representation of the quasi-optical output system of described gyrotron is used for the quasi-optical output system of gyrotron and uses the expression that ray, the quasi-optical resonant cavity application ray of gyrotron or optics are used ray.

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