CN117673685A - Radiator design method, radiator and multi-frequency millimeter wave mode conversion system - Google Patents
Radiator design method, radiator and multi-frequency millimeter wave mode conversion system Download PDFInfo
- Publication number
- CN117673685A CN117673685A CN202311502047.3A CN202311502047A CN117673685A CN 117673685 A CN117673685 A CN 117673685A CN 202311502047 A CN202311502047 A CN 202311502047A CN 117673685 A CN117673685 A CN 117673685A
- Authority
- CN
- China
- Prior art keywords
- radiator
- field distribution
- mode
- frequency
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000013461 design Methods 0.000 title claims abstract description 32
- 238000012937 correction Methods 0.000 claims abstract description 92
- 230000009191 jumping Effects 0.000 claims description 15
- 230000005540 biological transmission Effects 0.000 claims description 11
- 238000004364 calculation method Methods 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 3
- 238000011161 development Methods 0.000 abstract description 4
- 230000003287 optical effect Effects 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000004891 communication Methods 0.000 abstract description 2
- 238000005457 optimization Methods 0.000 description 13
- 238000010586 diagram Methods 0.000 description 8
- 230000000694 effects Effects 0.000 description 3
- 230000001788 irregular Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000004422 calculation algorithm Methods 0.000 description 2
- 239000008358 core component Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Landscapes
- Aerials With Secondary Devices (AREA)
Abstract
The invention discloses a radiator design method, a radiator and a multi-frequency millimeter wave mode conversion system, belonging to the field of wireless communication, wherein the design method comprises the following steps: on the basis of optimizing the circular waveguide radiator under different single frequency points, selecting a corresponding structure with highest efficiency, calculating a weighting coefficient, evaluating the frequency points needing to be continuously optimized and cooperatively optimizing the radiator structure so as to obtain high-purity Gaussian beams under the condition of multiple frequencies. The design method also provides a radiator and a multi-frequency millimeter wave mode conversion system. The multi-frequency millimeter wave mode conversion system only uses the radiator, the focusing mirror and the group of phase correction mirrors, realizes the output of Gaussian beams with higher purity, has simple design structure and low development difficulty, and solves the technical problems that the existing technology for designing the optical mode converter cannot be suitable for various frequencies and modes, has larger diffraction loss, has low Gaussian fundamental mode purity and the like.
Description
Technical Field
The invention belongs to the field of wireless communication, and particularly relates to a radiator design method, a radiator and a multi-frequency millimeter wave mode conversion system.
Background
Megawatt gyrotron is used as a high power millimeter wave source for Electron Cyclotron Resonance Heating (ECRH) or Electron Cyclotron Current Drive (ECCD) in magneto-confined fusion, etc. In megawatt gyrotrons, the resonant cavity typically operates in a higher order mode. In general, higher order phantoms are not suitable for direct useTransmission is performed, otherwise large transmission loss is caused. In general, a quasi-optical mode converter built in a gyrotron is required to perform mode conversion on a high-order body mode output by a resonant cavity, so that the mode conversion is converted into a high-purity Gaussian fundamental mode (TEM) which is convenient for efficient transmission 00 And (5) a mould). The megawatt gyrotron has high power level and has strict requirements on diffraction loss of an optical mode conversion system.
The radiator is used as one of core components of the mode conversion system and is used for converting millimeter waves in the gyrotron. The diffraction loss of the mode conversion system can be reduced by optimally designing the radiator structure. In the prior art, a radiator (such as a Fu Lasuo f radiator) with a smooth inner wall and no perturbation structure is adopted, so that the radiator is generally only suitable for millimeter wave conversion of a low-order mode under a low power condition, and a good conversion effect on millimeter waves of a high-order mode is difficult to obtain. In addition, most of the existing radiator structures and mode conversion systems have higher conversion efficiency for one or more specific frequencies and corresponding modes, and when the radiator structures and mode conversion systems are applied to other frequencies and modes, larger diffraction loss is generated, which causes TEM 00 The content of the mold is reduced.
The phase correction mirror is also one of the core components of the mode conversion system, and is used for performing phase correction on millimeter waves output from the radiator so as to obtain an output beam with higher Gaussian content. The phase correction mirrors adopted in the prior art are all smooth mirror structures, and parameters which can be changed in the design process are only the shape characteristic parameters of the smooth curved mirror, such as focal length, and the like, so that output beams with higher Gaussian content are difficult to obtain in multiple frequency and multiple modes.
Disclosure of Invention
Aiming at the defects and improvement demands of the prior art, the invention provides a radiator design method, a radiator and a multi-frequency millimeter wave mode conversion system, and aims to reduce diffraction loss of multi-frequency and multi-mode millimeter waves.
To achieve the above object, according to a first aspect of the present invention, there is provided a radiator design method, the radiator inner wall being provided with a disturbance, the design method comprising:
s1, calculating the disturbance amplitude of the inner wall of the radiator corresponding to millimeter waves under each frequency and mode;
s2, selecting a radiator with highest millimeter wave mode conversion efficiency and corresponding frequency and mode as a current radiator, and selecting the frequency and mode to be optimized;
s3, inputting the millimeter waves of each current frequency and mode to be optimized into the current radiator, and calculating the field distribution of the millimeter waves output by the current radiator and the disturbance amplitude of the inner wall of the corresponding current radiator; calculating the correlation coefficient between each field distribution and the target field distribution, and taking the magnitude of the correlation coefficient as the weight of the corresponding frequency and mode; the target field distribution is Gaussian-like distribution;
s4, multiplying the disturbance amplitude in the S3 by the weight of the corresponding frequency and mode, and adding the disturbance amplitude of the current radiator to serve as the updated current radiator; judging whether the correlation coefficients in the step S3 reach a preset threshold value, if not, taking the frequency and the mode corresponding to the correlation coefficient which does not reach the preset threshold value as the frequency and the mode to be optimized currently, and jumping to the step S3;
if yes, the updated current radiator is used as the optimal radiator.
Further, in S2, selecting a radiator with the highest millimeter wave mode conversion efficiency and corresponding mode, includes:
s21, respectively inputting millimeter waves in other frequencies and modes into corresponding radiators of the millimeter waves in the current frequencies and modes, and calculating field distribution of the millimeter waves corresponding to the radiators;
s22, calculating correlation coefficients between each field distribution and the target field distribution respectively, and taking the weighted average of the correlation coefficients as the comprehensive correlation coefficients of the radiators corresponding to the millimeter waves under the current frequency and the mode;
s23, selecting the next frequency and mode as the current frequency and mode, and jumping to S21 until the comprehensive correlation coefficient of the radiator corresponding to the millimeter wave under each frequency and mode is obtained;
s24, selecting the radiator with the highest comprehensive correlation coefficient as the radiator with the highest millimeter wave mode conversion efficiency and corresponding frequency and mode.
Further, in S2, selecting the frequency and mode to be optimized includes: and selecting the frequency and mode corresponding to the correlation coefficient between each field distribution and the target field distribution, which is obtained in the step S22, being lower than the set threshold value as the frequency and mode to be optimized.
Further, S1 includes:
s11, inputting millimeter waves under the current frequency and mode into a current radiator to obtain field distribution of output millimeter waves as current field distribution; the disturbance amplitude of the inner wall of the current radiator is 0;
s12, extracting the phase of the current field distribution, subtracting the phase of the current field distribution from the phase of the target field distribution, and substituting the obtained phase difference value into a disturbance calculation equation to obtain the current disturbance amplitude;
s13, substituting the current disturbance amplitude into a scalar diffraction equation, and obtaining new millimeter wave field distribution by adopting two-dimensional fast Fourier transform;
s14, taking the field distribution of the new millimeter wave as the current field distribution, and calculating the correlation coefficient of the current field distribution and the target field distribution; judging whether the correlation coefficient exceeds a preset threshold value or not;
if not, jumping to S12;
if yes, taking the current disturbance amplitude as the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under the current frequency and the mode; and taking the next frequency and mode as the current frequency and mode, and jumping to S11 until the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under each frequency and mode is obtained.
According to a second aspect of the invention, there is provided a radiator provided with a disturbance in its inner wall, the radiator being obtained by the design method according to any one of the first aspects.
According to a third aspect of the present invention, there is provided a multi-frequency millimeter wave mode conversion system comprising: a radiator, a focusing mirror and a phase correction mirror; the radiator is obtained by the design method according to any one of the first aspect, or the radiator is the radiator according to the second aspect;
the radiator is used for pre-bunching the input multi-frequency multi-mode millimeter waves;
the focusing lens is used for carrying out angular beam focusing on the millimeter waves of the pre-focusing beam;
the phase correction mirror is used for carrying out phase correction on millimeter waves after the angular beam focusing so as to output millimeter waves with Gaussian modes under corresponding frequencies from the gyrotron output window.
Further, the phase correction mirror comprises a first phase correction mirror and a second phase correction mirror; and the millimeter waves after the angular beam focusing pass through the first phase correcting mirror and the second phase correcting mirror in sequence for phase correction.
Further, the mirror surfaces of the first phase correcting mirror and the second phase correcting mirror are provided with disturbance structures, and the design method of the first phase correcting mirror and the second phase correcting mirror comprises the following steps:
s1, transmitting the millimeter wave of each frequency and mode output from the focusing mirror to the field distribution of a first phase correction mirror in a forward direction as a current field distribution; wherein the initial disturbance amplitude of the first phase correction mirror and the second phase correction mirror is 0;
s2, extracting amplitude B and phase B of each frequency and mode passing through the current field distribution, and transmitting millimeter waves to phase c of the field distribution of the second phase correcting mirror in the forward direction;
s3, assuming that a Gaussian millimeter wave is emitted from the output window of the gyrotron and is reversely transmitted to the second phase correcting lens, extracting the amplitude E and the phase E of the assumed field distribution at the second phase correcting lens to obtain the disturbance amplitude Deltax of the second phase correcting lens corresponding to each frequency and each mode 2 ＝(e-c)/(2kcosα 2 )，α 2 Representing the tilt of the second phase correction mirror, k representing the wavenumber of the millimeter wave in free space; taking the disturbance amplitude weighted average as the disturbance amplitude of the current second phase correction mirror;
s4, forming new field distribution at the second phase correcting mirror by the amplitude E of the assumed field distribution and the phase c of the forward transmission field distribution; extracting new field distribution reverse transmission to firstThe phase f of the field distribution at the phase correction mirror obtains the disturbance amplitude deltax of the first phase correction mirror corresponding to the current frequency and the mode 1 ＝(f-b)/(2kcosα 1 )，α 1 Representing the tilt angle of the first phase correction mirror; taking the disturbance amplitude weighted average as the disturbance amplitude of the current first phase correction mirror;
s5, forming new field distribution at the current first phase correction mirror by the amplitude B of the forward transmission field distribution and the phase f, taking the new field distribution as the current field distribution, jumping to S2, and taking the disturbance amplitude of the current first phase correction mirror and the disturbance amplitude of the second phase correction mirror as optimal disturbance if the preset cycle number is reached, so as to obtain the optimal first phase correction mirror and the optimal second phase correction mirror.
Further, the focusing lens is a quasi-elliptic cylindrical lens.
Further, the mirror equation of the focusing mirror is:
wherein l represents a propagation distance between the millimeter wave of the pre-beam output from the radiator and the focusing mirror surface;R c radius of the powder, l 1 And l 2 For the two focal lengths of the focusing mirror, < >>An exit angle from the radiator for the pre-bunched millimeter wave.
In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be obtained:
(1) According to the radiator structure designed by the invention, the disturbance structure is arranged on the inner wall of the radiator, millimeter waves are used as geometric light beams, local background refractive index changes are introduced on a transmission path of the light waves by utilizing micro disturbance to realize selection and conversion of different modes, the correlation coefficient between the radiator output field distribution and the target field distribution with the disturbance structure is calculated, the disturbance of the radiator is updated by taking the magnitude of the correlation coefficient as the weight of the corresponding frequency and mode, the optimization result under each single frequency point is subjected to weighted analysis to realize cooperative optimization under multiple frequency points, and the optimized radiator structure with the disturbance structure can be suitable for multi-frequency multi-mode high-order millimeter waves through iterative operation, can obtain output beams with similar Gaussian distribution close to the target field distribution, and can reduce diffraction loss of the multi-frequency multi-mode millimeter waves and improve the content of finally obtained Gaussian fundamental modes by using the Gaussian beams.
(2) Further, when the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under each frequency and mode is calculated, the existing integral equation method is not adopted, the phase of the field distribution is subtracted from the target field distribution, then two-dimensional fast Fourier transform is adopted to obtain new field distribution of the millimeter wave, the field distribution of the millimeter wave is taken as the field distribution of the millimeter wave under the current frequency and mode, and the corresponding disturbance amplitude of the inner wall of the radiator is calculated in a mode of calculating the correlation coefficient between the field distribution of the millimeter wave and the target field distribution; compared with the existing integral equation method, the method can skillfully utilize the advantages of two-dimensional fast Fourier transform, improve the calculation speed and further improve the optimization efficiency.
(3) Further, when initial iterative optimization is performed, the frequency with highest millimeter wave mode conversion efficiency and the radiator corresponding to the mode are selected as the current radiator, so that the iterative times can be reduced, the convergence speed of the algorithm is increased, and the optimization efficiency is further improved.
(4) Furthermore, the first phase correcting mirror and the second phase correcting mirror are irregular mirror surfaces, and the disturbance structure on the two phase correcting mirrors is designed through iteration optimization, and as the disturbance design of the phase correcting mirrors considers the correlation between the output field distribution corresponding to each frequency and mode and the target Gaussian field distribution, the first phase correcting mirror and the second phase correcting mirror designed in the invention can be used for carrying out phase adjustment on millimeter waves, so that phase correction applicable to a plurality of frequency points can be realized, and output beams with higher Gaussian content can be obtained.
(5) Furthermore, in the multi-frequency millimeter wave mode conversion system, the focusing mirror surface equation determined according to the propagation distance between the beam output by the radiator and the focusing mirror surface only considers the angular focusing of the beam output by the radiator, omits the adjustment of the angular phase difference in the propagation process of millimeter waves, and directly corrects the angular phase difference by adopting the phase correction mirror, so that the focusing mirror surface equation is simpler compared with the existing equation which is adapted to different mirrors according to different output positions of the radiator.
(6) The multi-frequency millimeter wave mode conversion system only uses the radiator, the focusing mirror and the group of phase correction mirrors, realizes the output of Gaussian beams with higher purity, has simple design structure and low development difficulty, and solves the technical problems that the existing technology for designing the optical mode converter cannot be suitable for various frequencies and modes, has larger diffraction loss, has low Gaussian fundamental mode purity and the like.
Drawings
Fig. 1 is a flowchart of a radiator design method in embodiment 1 of the present invention.
Fig. 2 is a schematic diagram of a multi-frequency millimeter wave mode conversion system in embodiment 3 of the present invention.
FIG. 3 shows 105GHz and TE according to an embodiment of the present invention 18,6 And (5) a radiator inner wall disturbance structure development diagram.
FIG. 4 shows 105GHz and TE according to an embodiment of the present invention 18,6 Schematic diagram of the distribution of the field on the inner wall of the radiator.
Fig. 5 is a schematic diagram of an ideal field distribution.
Fig. 6 is a schematic diagram of a quasi-elliptical cylindrical lens field distribution according to an embodiment of the present invention.
Fig. 7 is a schematic diagram of a mirror structure of a first phase correction mirror according to an embodiment of the present invention.
Fig. 8 is a schematic diagram of a mirror structure of a second phase correction mirror according to an embodiment of the invention.
Fig. 9 is a schematic diagram of an output field distribution after being rectified by a first phase rectification mirror and a second phase rectification mirror in an embodiment of the present invention.
The same reference numbers are used throughout the drawings to reference like elements or structures, wherein:
1-radiator, 2-focusing mirror, 3-first phase correction mirror, 4-second phase correction mirror, 5-output window.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In the present invention, the terms "first," "second," and the like in the description and in the drawings are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
Example 1
As shown in fig. 1, the present invention provides a design method of a radiator, wherein a disturbance is provided on an inner wall of the radiator, and the design method includes:
s1, calculating the disturbance amplitude of the inner wall of the radiator corresponding to millimeter waves under each frequency and mode; wherein the millimeter wave is a millimeter wave of a higher order mode;
s2, selecting a radiator with highest millimeter wave mode conversion efficiency and corresponding frequency and mode as a current radiator, and selecting the frequency and mode to be optimized;
s3, inputting the millimeter waves of each current frequency and mode to be optimized into the current radiator, and calculating the field distribution of the millimeter waves output by the current radiator and the disturbance amplitude of the inner wall of the corresponding current radiator; calculating the correlation coefficient between each field distribution and the target field distribution, and taking the magnitude of the correlation coefficient as the weight of the corresponding frequency and mode; the target field distribution in the embodiment is gaussian-like distribution;
s4, multiplying the disturbance amplitude in the S3 by the weight of the corresponding frequency and mode, and adding the disturbance amplitude of the current radiator to serve as the updated current radiator; judging whether the correlation coefficients in the step S3 all reach a preset threshold value, if not, taking the frequency and the mode corresponding to the correlation coefficient which does not reach the preset threshold value as the current frequency and the mode to be optimized, and jumping to the step S3; if yes, the updated current radiator is used as the optimal radiator.
Specifically, in S1, calculating the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave in each frequency and mode includes:
s11, inputting millimeter waves under the current frequency and mode into a current radiator to obtain field distribution of output millimeter waves as current field distribution; the disturbance amplitude of the inner wall of the current radiator is 0;
s12, extracting the phase of the current field distribution, subtracting the phase of the current field distribution from the phase of the target field distribution, and substituting the obtained phase difference value into a disturbance calculation equation to obtain the current disturbance amplitude;
s13, substituting the current disturbance amplitude into a scalar diffraction equation, and obtaining new millimeter wave field distribution by adopting two-dimensional fast Fourier transform;
s14, taking the field distribution of the new millimeter wave as the current field distribution, and calculating the correlation coefficient of the current field distribution and the target field distribution; judging whether the correlation coefficient exceeds a preset threshold value or not;
if not, jumping to S12;
if yes, taking the current disturbance amplitude obtained in the step S12 as the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under the current frequency and the mode; and taking the next frequency and mode as the current frequency and mode, and jumping to S11 until the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under each frequency and mode is obtained.
Specifically, in S12, the target field distribution may be decomposed into nine different modes according to table 1 for the current frequency and mode, and the desired target field distribution may be obtained by superimposing the power ratios of the nine different modes.
TABLE 1TE mode selection and relative Power level superimposed into Gaussian fundamental mode
In table 1, the power ratio corresponding to this mode is shown in parentheses.
Specifically, in S2, selecting a radiator with the highest millimeter wave mode conversion efficiency and corresponding mode includes:
s21, respectively inputting millimeter waves in other frequencies and modes into corresponding radiators of the millimeter waves in the current frequencies and modes, and calculating field distribution of the millimeter waves corresponding to the radiators;
s22, calculating correlation coefficients between each field distribution and the target field distribution respectively, and taking the weighted average of the phase relation numbers as the comprehensive correlation coefficient of the radiator corresponding to the millimeter wave under the current frequency and mode;
s23, selecting the next frequency and mode as the current frequency and mode, and jumping to S21 until the comprehensive correlation coefficient of the radiator corresponding to the millimeter wave under each frequency and mode is obtained;
s24, selecting the radiator with the highest comprehensive correlation coefficient as the radiator with the highest millimeter wave mode conversion efficiency and corresponding frequency and mode.
Specifically, in S2, selecting the frequency and mode to be optimized includes:
and selecting the frequency and mode corresponding to the correlation coefficient between each field distribution and the target field distribution, which is obtained in the step S22, being lower than the set threshold value as the frequency and mode to be optimized.
Specifically, in S3, calculating a corresponding disturbance amplitude of the inner wall of the current radiator includes:
extracting the phase of the field distribution of the millimeter wave corresponding to the output of the current radiator; and subtracting the phase of the field distribution from the phase of the target field distribution, and substituting the obtained phase difference value into a disturbance calculation equation to obtain the corresponding disturbance amplitude.
According to the radiator structure designed by the invention, the disturbance structure is arranged on the inner wall of the radiator, millimeter waves are used as geometric light beams, local background refractive index changes are introduced on a transmission path of the light waves by utilizing micro disturbance to realize selection and conversion of different modes, the correlation coefficient between the radiator output field distribution and the target field distribution with the disturbance structure is calculated, the disturbance of the radiator is updated by taking the magnitude of the correlation coefficient as the weight of the corresponding frequency and mode, the optimization result under each single frequency point is subjected to weighted analysis to realize cooperative optimization under multiple frequency points, and the optimized radiator structure with the disturbance structure can be suitable for multi-frequency multi-mode high-order millimeter waves through iterative operation, can obtain output beams with similar Gaussian distribution close to the target field distribution, and can reduce diffraction loss of the multi-frequency multi-mode millimeter waves and improve the content of finally obtained Gaussian fundamental modes by using the Gaussian beams.
Meanwhile, when the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under each frequency and mode is calculated, the existing integral equation method is not adopted, the phase of the field distribution is subtracted from the target field distribution, the two-dimensional fast Fourier transform is adopted to obtain the new field distribution of the millimeter wave, the field distribution of the millimeter wave is taken as the field distribution of the millimeter wave under the current frequency and mode, and the corresponding disturbance amplitude of the inner wall of the radiator is calculated in a mode of calculating the correlation coefficient between the field distribution of the millimeter wave and the target field distribution; compared with the existing integral equation method, the method can skillfully utilize the advantages of two-dimensional fast Fourier transform, improve the calculation speed and further improve the optimization efficiency.
And when initial iterative optimization is carried out, the frequency with highest millimeter wave mode conversion efficiency and the radiator corresponding to the mode are selected as the current radiator, so that the iterative times can be reduced, the convergence speed of the algorithm is increased, and the optimization efficiency is further improved.
Example 2
The embodiment of the invention provides a radiator structure, wherein the inner wall of a radiator is provided with disturbance; wherein the radiator is obtained by the radiator design method in embodiment 1.
Example 3
As shown in fig. 2, an embodiment of the present invention provides a multi-frequency millimeter wave mode conversion system, including: a radiator 1, a focusing mirror 2 and a phase correction mirror; wherein the radiator 1, the focusing mirror 2 and the phase correction mirror are all arranged in the gyrotron; the radiator is the radiator obtained by the radiator design method in the embodiment 1, or/and the radiator in the embodiment 2;
a radiator 1 for pre-bunching an input multi-frequency multi-mode millimeter wave;
a focusing mirror 2 for performing angular focusing on the millimeter waves of the pre-focusing;
and the phase correction mirror is used for carrying out phase correction on the millimeter waves after the angular beam focusing, and further outputting the millimeter waves with Gaussian modes under corresponding frequencies from the output window 5 of the gyrotron.
Specifically, in the embodiment of the present invention, the focusing mirror 2 is a quasi-elliptical cylindrical mirror, and can receive and focus the output beam of the radiator through its specific focusing property and beam size matching capability. The quasi-elliptical cylindrical mirror has two foci, one focus being located in the centre of the radiator and the other focus being located at a distance l from the centre of the radiator 2 Is a position of (c).
The mirror equation of the focusing mirror 2 is:
where l represents a propagation distance between the millimeter wave of the pre-beam output from the radiator 1 and the mirror surface of the focusing mirror 2;R c radius of the powder, l 1 And l 2 For the two focal lengths of the focusing mirror 2, < >>To output an exit angle of millimeter waves from the radiator 1.
In the multi-frequency millimeter wave mode conversion system, the focusing mirror surface equation determined according to the propagation distance between the beam output by the radiator and the focusing mirror surface only considers the angular beam focusing of the beam output by the radiator, omits the adjustment of the angular phase difference of millimeter waves in the propagation process, and directly corrects the angular phase difference by adopting the phase correction mirror, so that the focusing mirror surface equation is simpler compared with the existing equation which is adapted to different mirrors according to different output positions of the radiator.
As preferable, the phase correction mirror in the embodiment of the present invention includes a first phase correction mirror 3 and a second phase correction mirror 4; the mirror surfaces of the first phase correcting mirror 3 and the second phase correcting mirror 4 are provided with disturbance structures, and millimeter waves of each frequency and mode output from the focusing mirror pass through the first phase correcting mirror 3 and the second phase correcting mirror 4 in sequence for phase correction; the design method of the first phase correction mirror 3 and the second phase correction mirror 4 comprises the following steps:
s1, transmitting the millimeter wave of each frequency and mode output from the focusing mirror to the field distribution of the first phase correction mirror 3 in the forward direction as the current field distribution; setting the initial disturbance amplitude of the first phase correction mirror 3 and the second phase correction mirror 4 to 0;
s2, extracting amplitude B and phase B of each frequency and mode passing through the current field distribution, and transmitting millimeter waves to phase c of the field distribution of the second phase correcting mirror 4 in the forward direction;
s3, a Gaussian millimeter wave is emitted from the output window of the assumed gyrotron and is reversely transmitted to the second phase correcting mirror 4, the assumed field distribution of the Gaussian millimeter wave reversely transmitted to the second phase correcting mirror 4 is calculated, the amplitude E and the phase E of the assumed field distribution are extracted, and the disturbance amplitude Deltax of the second phase correcting mirror 4 corresponding to each frequency and each mode is obtained 2 ＝(e-c)/(2kcosα 2 ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein alpha is 2 Represents the tilt angle of the second phase correction mirror 4; k represents the wavenumber of the millimeter wave in the free space; taking the weighted average of the disturbance amplitude of the second phase correction mirror 4 corresponding to each frequency and each mode as the disturbance amplitude of the current second phase correction mirror 4;
s4, forming a new field distribution at the second phase correction mirror 4 by the amplitude E of the assumed field distribution and the phase c of the forward transmission field distribution; is transmitted back to the first phase correction mirror 3 from the new field distribution and the corresponding field distribution is extractedPhase f, obtaining disturbance amplitude Deltax of the first phase correction mirror 3 corresponding to the current frequency and mode 1 ＝(f-b)/(2kcosα 1 ) Wherein alpha is 1 Representing the tilt angle of the first phase correction mirror 3; taking the disturbance amplitude weighted average of the first phase correction mirror 3 corresponding to each frequency and each mode as the disturbance amplitude of the current first phase correction mirror 3;
s5, forming new field distribution at the current first phase correction mirror 3 by the amplitude B of the forward transmission field distribution and the phase f, taking the new field distribution as the current field distribution, jumping to S2, and taking the disturbance amplitude of the current first phase correction mirror 3 and the disturbance amplitude of the second phase correction mirror 4 as optimal disturbance if the preset cycle number is reached, so as to obtain the optimal first phase correction mirror 3 and the second phase correction mirror 4.
According to the invention, the first phase correction mirror 3 and the second phase correction mirror 4 are irregular mirror surfaces, and the disturbance structures on the two phase correction mirrors are designed through iterative optimization, and as the disturbance design of the phase correction mirrors considers the correlation between the output field distribution corresponding to each frequency and mode and the target Gaussian field distribution, the first phase correction mirror 3 and the second phase correction mirror 4 designed in the invention can be used for carrying out phase adjustment on millimeter waves, so that phase correction applicable to a plurality of frequency points can be realized, and output beams with higher Gaussian content can be obtained.
The multi-frequency millimeter wave mode conversion system only uses the radiator, the focusing mirror and a group of phase correction mirrors, realizes the output of Gaussian beams with higher purity, and has simple design structure and low development difficulty. The technical problems that the existing technology for designing the alignment optical mode converter cannot be suitable for various frequencies and modes, the diffraction loss is large, the Gaussian fundamental mode purity is low and the like are solved.
Simulation results of the transformation system of the present invention are further described below with specific examples.
The embodiment of the invention is applied to the frequency of 105GHz, and the working mode is TE 18,6 The initial radius of the radiator is 20.5mm and the length is 140mm; the optimized inner wall package was obtained by the design method of example 1A radiator comprising an irregular perturbation structure; in the embodiment of the invention, the disturbance structure on the inner wall of the radiator is a perturbation structure, and the amplitude of disturbance is +/-1 mm.
The optimized radiator structure is shown in fig. 3, the corresponding field distribution is shown in fig. 4, and the ideal field distribution is shown in fig. 5; the vector correlation coefficient with the ideal field (gaussian-like distribution) at the end of the radiator can be 97.9% by the optimized radiator, and the scalar correlation coefficient is 99.4%. That is, the radiator structure designed by the invention can set the frequency to 105GHz and the working mode to TE 18,6 The millimeter wave of the (C) is converted into the millimeter wave with Gaussian-like distribution, the conversion efficiency is higher, and similar better effects can be still achieved under other frequencies and modes.
In the design of the quasi-elliptic cylindrical mirror, in order to receive as many microwaves radiated by a radiator as possible and realize a certain focusing effect, l 1 Requires more than twice the inner radius of the radiator, l 2 As much as possible, a value of at least 10l is chosen 1 . In the embodiment of the invention, in l 1 Selected as 50mm, l 2 2000mm, 105GHz frequency, TE mode 18,6 The field distribution on the quasi-elliptic cylindrical mirror is calculated as shown in fig. 6, and it can be seen that the field distribution on the quasi-elliptic cylindrical mirror is also a gaussian-like distribution field.
For 105GHz, TE 18,6 The structures of the radiator and the quasi-elliptic cylindrical mirror are designed, the phase correction mirror structure which is designed through iterative optimization is shown in fig. 7 and 8, and the vertical axis represents the amplitude of the mirror disturbance. The output field distribution after the first phase correcting mirror and the second phase correcting mirror are integrated is calculated based on scalar diffraction theory, and the final field distribution is obtained, as shown in fig. 9, and the distribution is quite close to ideal Gaussian distribution, and the correlation coefficient can reach 97.97%.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. A radiator design method, characterized in that the radiator inner wall is provided with a disturbance, the design method comprising:
s1, calculating the disturbance amplitude of the inner wall of the radiator corresponding to millimeter waves under each frequency and mode;
s2, selecting a radiator with highest millimeter wave mode conversion efficiency and corresponding frequency and mode as a current radiator, and selecting the frequency and mode to be optimized;
s3, inputting the millimeter waves of each current frequency and mode to be optimized into the current radiator, and calculating the field distribution of the millimeter waves output by the current radiator and the disturbance amplitude of the inner wall of the corresponding current radiator; calculating the correlation coefficient between each field distribution and the target field distribution, and taking the magnitude of the correlation coefficient as the weight of the corresponding frequency and mode; the target field distribution is Gaussian-like distribution;
s4, multiplying the disturbance amplitude in the S3 by the weight of the corresponding frequency and mode, and adding the disturbance amplitude of the current radiator to serve as the updated current radiator; judging whether the correlation coefficients in the step S3 reach a preset threshold value, if not, taking the frequency and the mode corresponding to the correlation coefficient which does not reach the preset threshold value as the frequency and the mode to be optimized currently, and jumping to the step S3;
if yes, the updated current radiator is used as the optimal radiator.
2. The design method according to claim 1, wherein in S2, selecting the radiator with the highest millimeter wave mode conversion efficiency and the corresponding mode includes:
s21, respectively inputting millimeter waves in other frequencies and modes into corresponding radiators of the millimeter waves in the current frequencies and modes, and calculating field distribution of the millimeter waves corresponding to the radiators;
s22, calculating correlation coefficients between each field distribution and the target field distribution respectively, and taking the weighted average of the correlation coefficients as the comprehensive correlation coefficients of the radiators corresponding to the millimeter waves under the current frequency and the mode;
s23, selecting the next frequency and mode as the current frequency and mode, and jumping to S21 until the comprehensive correlation coefficient of the radiator corresponding to the millimeter wave under each frequency and mode is obtained;
s24, selecting the radiator with the highest comprehensive correlation coefficient as the radiator with the highest millimeter wave mode conversion efficiency and corresponding frequency and mode.
3. The design method according to claim 2, wherein in S2, selecting the frequency and mode to be optimized comprises: and selecting the frequency and mode corresponding to the correlation coefficient between each field distribution and the target field distribution, which is obtained in the step S22, being lower than the set threshold value as the frequency and mode to be optimized.
4. The design method according to claim 1, wherein S1 includes:
s11, inputting millimeter waves under the current frequency and mode into a current radiator to obtain field distribution of output millimeter waves as current field distribution; the disturbance amplitude of the inner wall of the current radiator is 0;
s12, extracting the phase of the current field distribution, subtracting the phase of the current field distribution from the phase of the target field distribution, and substituting the obtained phase difference value into a disturbance calculation equation to obtain the current disturbance amplitude;
s13, substituting the current disturbance amplitude into a scalar diffraction equation, and obtaining new millimeter wave field distribution by adopting two-dimensional fast Fourier transform;
s14, taking the field distribution of the new millimeter wave as the current field distribution, and calculating the correlation coefficient of the current field distribution and the target field distribution; judging whether the correlation coefficient exceeds a preset threshold value or not;
if not, jumping to S12;
if yes, taking the current disturbance amplitude as the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under the current frequency and the mode; and taking the next frequency and mode as the current frequency and mode, and jumping to S11 until the disturbance amplitude of the inner wall of the radiator corresponding to the millimeter wave under each frequency and mode is obtained.
5. A radiator, characterized in that the radiator is provided with turbulence in its inner wall, which radiator is obtained by the design method according to any one of claims 1-4.
6. A multi-frequency millimeter wave mode conversion system, comprising: a radiator, a focusing mirror and a phase correction mirror; wherein the radiator is obtained by the design method of any one of claims 1 to 4, or the radiator is the radiator of claim 5;
the radiator is used for pre-bunching the input multi-frequency multi-mode millimeter waves;
the focusing lens is used for carrying out angular beam focusing on the millimeter waves of the pre-focusing beam;
the phase correction mirror is used for carrying out phase correction on millimeter waves after the angular beam focusing so as to output millimeter waves with Gaussian modes under corresponding frequencies from the gyrotron output window.
7. The multiple frequency millimeter wave mode conversion system according to claim 6, wherein said phase correction mirror comprises a first phase correction mirror and a second phase correction mirror; and the millimeter waves after the angular beam focusing pass through the first phase correcting mirror and the second phase correcting mirror in sequence for phase correction.
8. The system according to claim 7, wherein the first phase correction mirror and the second phase correction mirror are provided with disturbance structures on mirror surfaces, and the method for designing the first phase correction mirror and the second phase correction mirror comprises:
s1, transmitting the millimeter wave of each frequency and mode output from the focusing mirror to the field distribution of a first phase correction mirror in a forward direction as a current field distribution; wherein the initial disturbance amplitude of the first phase correction mirror and the second phase correction mirror is 0;
s2, extracting amplitude B and phase B of each frequency and mode passing through the current field distribution, and transmitting millimeter waves to phase c of the field distribution of the second phase correcting mirror in the forward direction;
s3, assuming that a Gaussian millimeter wave is emitted from the output window of the gyrotron and is reversely transmitted to the second phase correcting lens, extracting the amplitude E and the phase E of the assumed field distribution at the second phase correcting lens to obtain the disturbance amplitude Deltax of the second phase correcting lens corresponding to each frequency and each mode 2 ＝(e-c)/(2kcosα 2 )，α 2 Representing the tilt of the second phase correction mirror, k representing the wavenumber of the millimeter wave in free space; taking the disturbance amplitude weighted average as the disturbance amplitude of the current second phase correction mirror;
s4, forming new field distribution at the second phase correcting mirror by the amplitude E of the assumed field distribution and the phase c of the forward transmission field distribution; extracting new field distribution and reversely transmitting the new field distribution to the phase f of the field distribution at the first phase correcting lens to obtain the disturbance amplitude deltax of the first phase correcting lens corresponding to the current frequency and the mode 1 ＝(f-b)/(2kcosα 1 )，α 1 Representing the tilt angle of the first phase correction mirror; taking the disturbance amplitude weighted average as the disturbance amplitude of the current first phase correction mirror;
s5, forming new field distribution at the current first phase correction mirror by the amplitude B of the forward transmission field distribution and the phase f, taking the new field distribution as the current field distribution, jumping to S2, and taking the disturbance amplitude of the current first phase correction mirror and the disturbance amplitude of the second phase correction mirror as optimal disturbance if the preset cycle number is reached, so as to obtain the optimal first phase correction mirror and the optimal second phase correction mirror.
9. The system of any of claims 6-8, wherein the focusing mirror is a quasi-elliptical cylindrical mirror.
10. The multiple frequency millimeter wave mode conversion system according to claim 9, wherein the mirror equation of the focusing mirror is:
wherein l represents a propagation distance between the millimeter wave of the pre-beam output from the radiator and the focusing mirror surface;R c radius of the powder, l 1 And l 2 For the two focal lengths of the focusing mirror, < >>An exit angle from the radiator for the pre-bunched millimeter wave. />
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311502047.3A CN117673685A (en) | 2023-11-10 | 2023-11-10 | Radiator design method, radiator and multi-frequency millimeter wave mode conversion system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311502047.3A CN117673685A (en) | 2023-11-10 | 2023-11-10 | Radiator design method, radiator and multi-frequency millimeter wave mode conversion system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117673685A true CN117673685A (en) | 2024-03-08 |
Family
ID=90074352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311502047.3A Pending CN117673685A (en) | 2023-11-10 | 2023-11-10 | Radiator design method, radiator and multi-frequency millimeter wave mode conversion system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117673685A (en) |
-
2023
- 2023-11-10 CN CN202311502047.3A patent/CN117673685A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Bogdashov et al. | Mirror synthesis for gyrotron quasi-optical mode converters | |
| Teniente et al. | Design guidelines of horn antennas that combine horizontal and vertical corrugations for satellite communications | |
| CN108134163B (en) | The aiming light mode converting means and its method of Terahertz multimode frequency is adjustable gyrotron | |
| Jin et al. | Quasi-optical mode converter/mirror system for a high-power coaxial-cavity gyrotron | |
| CN105529538B (en) | A kind of high power millimeter wave broadband mode converter based on continuous optical grating construction | |
| Wang et al. | A broadband TE 01–TE 11 mode converter with elliptical section for Gyro-TWTs | |
| Zhao et al. | Design of quasi-optical mode converter for 170-GHz TE 32, 9-mode high-power gyrotron | |
| CN117673685A (en) | Radiator design method, radiator and multi-frequency millimeter wave mode conversion system | |
| CN102956415A (en) | Ray representation method of gyrotron quasi-optical output system | |
| Kowalski et al. | Simple correctors for elimination of high-order modes in corrugated waveguide transmission lines | |
| JP3166869B2 (en) | Method for converting a TE mode to an EHmn-type hybrid mode, and a helical aperture antenna for implementing the method | |
| Shapiro et al. | Study of combined transmission line for high power wave generated by a gyrotron in the millimetre wavelength range | |
| Jin et al. | A Compact Dual-Mirror Design of Quasi-Optical Mode Converter for Gyrotron Application | |
| CN110739519B (en) | Phase correction surface type power combiner design method based on quasi-optical theory | |
| Jin et al. | High-efficiency quasi-optical mode converter for the coaxial cavity gyrotron | |
| Choi et al. | Calculation of radiation from a helically cut waveguide for a gyrotron mode converter in the quasi-optical approximation | |
| Sobolev et al. | Minimization of diffraction losses in big gaps of multi-mode waveguides | |
| CN112764214A (en) | Diffraction simulation method for generating hollow light beam | |
| Vernon | High-power microwave transmission and mode conversion program | |
| Rock et al. | A power-optimizing integrated design of a dual-frequency gyrotron quasi-optical mode converter | |
| Zhu et al. | Discussion on the Phase-Correction Mirror in the Quasi-Optical Mode Converter | |
| CN116413924A (en) | Millimeter wave annular beam implementation method and system | |
| Zhang et al. | Design of 170GHz TE 11-HE 11 Mode Converter | |
| Jin et al. | Design of matching optics unit (MOU) for coaxial ITER gyrotron | |
| Thumm et al. | Quasi-optical mode converters in advanced high-power gyrotrons for nuclear fusion plasma heating |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |