Microwave artificial diamond production apparatus

Abstract

The present invention is a microwave artificial diamond production device, which comprises a reaction container and a microwave emission module. A diamond seed is placed in the reaction container. The microwave emission module comprises a mode conversion tube, a guide tube, a first waveguide tube and a first linear polarization microwave source, and a second waveguide tube and a first matching load connected in sequence. The mode conversion tube is connected to the reaction container and can convert microwave between circular polarization mode and linear polarization mode. The guide tube has a first opening and a second opening which are not parallel and are connected to the first waveguide tube and the second waveguide tube respectively. The first linear polarization microwave source is arranged in the first waveguide tube, and the first matching load is arranged in the second waveguide tube. In this way, the reflected microwave in the reaction container which is not used can be absorbed by the first matching load, thereby improving the diamond production efficiency.

Description

Technical Field

[0001] This invention relates to an apparatus for producing synthetic diamonds, and more particularly to an apparatus for producing synthetic diamonds using microwave plasma chemical vapor deposition (MPCVD). Background Technology

[0002] Existing MPCVD synthetic diamond production equipment includes a reaction chamber and a microwave emitting module. A diamond stage is installed within the reaction chamber; the microwave emitting module emits 2.45 GHz microwaves into the reaction chamber, creating a regional standing wave electric field at the diamond stage. During synthetic diamond production, a diamond seed crystal is placed on the diamond stage, and high-concentration methane is injected into the reaction chamber. The microwave energy emitted by the microwave emitting module heats the methane gas surrounding the diamond seed crystal to extremely high temperatures, forming plasma spheres. Carbon atoms in the methane gas are then attracted to the diamond seed crystal by the plasma, causing the diamond seed crystal to gradually grow into a larger synthetic diamond.

[0003] To enhance the production efficiency of synthetic diamond production equipment, Taiwan Patent No. TWI734405B discloses a synthetic diamond production device with a circularly polarized tube and a focusing mechanism. After the microwave is converted into circularly polarized microwave by the circularly polarized tube, it is focused on the diamond seed crystal by the focusing mechanism, so that plasma balls can be stably formed around the diamond seed crystal, thereby improving the production efficiency of synthetic diamonds.

[0004] However, during actual testing, it was found that while circularly polarized microwaves help stabilize the formation of plasma spheres, they also easily cause multiple reflections within the reaction cavity due to impedance mismatch. This results in complex, multi-reflection standing waves between the microwave emitting module and the reaction cavity, which in turn damages the stability of the plasma spheres surrounding the diamond seed crystal, leading to a decrease in production efficiency. In short, while the synthetic diamond production device designed according to Taiwan Patent No. TWI734405B can theoretically improve the production efficiency of synthetic diamonds, in actual operation, the accumulation of excessive useless microwave energy within the reaction cavity prevents the diamond production efficiency from reaching the expected level.

[0005] Therefore, existing synthetic diamond production equipment and its microwave emission module need to be improved. Summary of the Invention

[0006] In view of the aforementioned shortcomings and deficiencies of the prior art, the present invention provides a microwave artificial diamond production device that can avoid the formation of complex multi-reflection standing waves between the microwave transmitting module and the reaction cavity due to multiple microwave reflections within the reaction cavity.

[0007] To achieve the above objectives, the technical means employed in this invention is to design a microwave synthetic diamond production apparatus, comprising:

[0008] A reaction vessel, which is a hollow body, has a microwave viewing window for allowing external microwaves to penetrate into the reaction vessel. The reaction vessel has...

[0009] A diamond stage is disposed within the reaction vessel and defines a focusing region;

[0010] A microwave transmitting module is disposed outside the reaction vessel and emits circularly polarized microwaves toward the microwave window of the reaction vessel. The microwave transmitting module includes a mode converter, a guide tube, a first waveguide, and a first linearly polarized microwave source connected in sequence. The microwave transmitting module also includes a second waveguide and a first matching load.

[0011] The mode conversion tube has

[0012] A circular polarization opening is located at one end of the mode conversion tube and faces the microwave window of the reaction vessel;

[0013] A linear polarization opening is located at the other end of the mode switching tube. When external linearly polarized microwaves enter the mode switching tube through the linear polarization opening, the linearly polarized microwaves are converted into circularly polarized microwaves and emitted from the circularly polarized opening. When external circularly polarized microwaves enter the mode switching tube through the circularly polarized opening, the circularly polarized microwaves are converted into linearly polarized microwaves and emitted from the linearly polarized opening.

[0014] The guide tube has the following features:

[0015] A main opening is located at one end of the guide tube and is connected to the linear polarization opening of the mode conversion tube;

[0016] The first thing to say;

[0017] A second opening is located on the wall of the guide tube; the direction of the second opening is not parallel to the direction of the first opening;

[0018] One end of the first waveguide is connected to the first opening of the waveguide, and the other end is connected to the first linearly polarized microwave source;

[0019] The first linearly polarized microwave source generates linearly polarized microwaves, which are converted into circularly polarized microwaves by the mode conversion tube and emitted toward the microwave window of the reaction vessel through the circularly polarized opening of the mode conversion tube.

[0020] One end of the second waveguide is connected to the second opening of the guide tube;

[0021] The first matching load is located on the second waveguide;

[0022] A microwave lens is disposed between the circular polarization opening of the mode conversion tube of the microwave transmitting module and the diamond stage of the reaction vessel; the microwave lens focuses the circularly polarized microwaves emitted by the microwave transmitting module onto the focusing area of ​​the diamond stage.

[0023] Furthermore, in the microwave synthetic diamond production apparatus, the microwave transmitting module has a second linearly polarized microwave source disposed at the other end of the second waveguide; and a second matching load disposed at the first waveguide.

[0024] Furthermore, in the microwave synthetic diamond production apparatus, the guide tube of the microwave emitting module is a round tube; the first waveguide and the second waveguide of the microwave emitting module are square tubes.

[0025] Furthermore, in the microwave synthetic diamond production apparatus, the first opening of the guide tube is located at one end of the guide tube opposite to the main opening; the microwave emitting module has a square-to-round connecting tube, which connects the first waveguide tube and the first opening of the guide tube; the inner wall of the square-to-round connecting tube gradually changes from square to round.

[0026] Furthermore, in the microwave synthetic diamond production apparatus, the first opening of the guide tube is located at one end of the guide tube opposite to the main opening; the microwave transmitting module has a connecting sleeve fitted over the guide tube, and the second waveguide is connected to the outer wall of the connecting sleeve; the connecting sleeve has a conversion hole that extends from the outer wall to the inner wall and is an elongated hole; the two opposite openings of the conversion hole are respectively connected to the second opening of the guide tube and the second waveguide, and the width of the conversion hole gradually decreases towards the second opening.

[0027] Furthermore, in the microwave synthetic diamond production apparatus, the opposing walls of the conversion hole are stepped, causing the width of the conversion hole to gradually narrow towards the second opening.

[0028] Furthermore, in the microwave synthetic diamond production apparatus, the microwave emitting module has a connecting sleeve fitted over the guide tube, and the second waveguide is connected to the outer wall of the connecting sleeve; the connecting sleeve has a conversion hole that extends from the outer wall to the inner wall and is an elongated hole; the two opposite openings of the conversion hole are respectively connected to the second opening of the guide tube and the second waveguide, and the width of the conversion hole gradually decreases towards the second opening.

[0029] Furthermore, in the microwave synthetic diamond production apparatus, the opposing walls of the conversion hole are stepped, causing the width of the conversion hole to gradually narrow towards the second opening.

[0030] Furthermore, in the microwave synthetic diamond production apparatus, the first opening of the guide tube is located on the tube wall of the guide tube; the microwave emitting module has a connecting sleeve fitted over the guide tube, and the second waveguide is connected to the outer wall of the connecting sleeve; the connecting sleeve has two conversion holes; each conversion hole extends from the outer wall to the inner wall of the connecting sleeve and is an elongated hole; one of the two opposite openings of the conversion hole is connected to the first opening of the guide tube and the first waveguide respectively; the other of the two opposite openings of the conversion hole is connected to the second opening of the guide tube and the second waveguide respectively; the width of each conversion hole gradually decreases towards the outer wall of the guide tube.

[0031] Furthermore, in the microwave synthetic diamond production apparatus, the opening direction of the first opening of the guide tube is perpendicular to the opening direction of the second opening.

[0032] The advantage of this invention lies in that, by incorporating a mode conversion tube, a guide tube, and a first matching load into the microwave transmitting module, when circularly polarized microwaves in the reaction vessel are reflected due to impedance mismatch or other reasons, the reflected circularly polarized microwaves can be converted back into linearly polarized microwaves by the mode conversion tube. These microwaves are then emitted through the second opening of the guide tube to the first matching load, where they are converted into heat energy. In this way, the invention can channel unwanted microwave energy in the reaction vessel, prevent the formation of complex multi-reflection standing waves, and thus maintain the stability of the plasma sphere around the diamond seed crystal and improve diamond production efficiency.

[0033] Specifically, the linearly polarized microwaves emitted by the first linearly polarized microwave source enter the mode conversion tube through the guide tube, are converted into circularly polarized microwaves, and then injected into the reaction vessel to assist in diamond formation. The circularly polarized microwaves reflected from the reaction vessel are then converted back into linearly polarized microwaves by the mode conversion tube. However, after being converted twice by the mode conversion tube, the electric field angle of these linearly polarized microwaves (hereinafter referred to as reflected microwaves) becomes perpendicular to the original emitted linearly polarized microwaves. Therefore, the reflected microwaves can no longer leave the guide tube through the original first opening. Consequently, excessive useless microwave energy accumulates in the reaction cavity of the traditional Taiwanese patent No. TWI734405B. In contrast, the guide tube of this invention has a second opening that is not parallel to the first opening. Therefore, the reflected microwaves can leave the guide tube through the second opening, thereby dissipating the useless microwave energy in the reaction vessel. Attached Figure Description

[0034] Figure 1 This is a perspective view of the first embodiment of the present invention.

[0035] Figure 2 This is an exploded view of the three-dimensional components according to the first embodiment of the present invention.

[0036] Figure 3 This is a three-dimensional cross-sectional view of some components of the first embodiment of the present invention.

[0037] Figure 4 This is a longitudinal partial sectional view of the first embodiment of the present invention.

[0038] Figure 5 This is a cross-sectional schematic diagram of the first embodiment of the present invention.

[0039] Figure 6 This is a perspective view of the second embodiment of the present invention.

[0040] Figure 7 This is an exploded view of the three-dimensional components according to the second embodiment of the present invention.

[0041] Figure 8 This is a longitudinal sectional view of the second embodiment of the present invention.

[0042] Figure 9 This is the second embodiment of the present invention. Figure 8 A schematic diagram of the transverse cross-section of the AA section line. Detailed Implementation

[0043] The following description, in conjunction with the accompanying drawings and preferred embodiments of the invention, further illustrates the technical means employed by the present invention to achieve its intended purpose.

[0044] Please see Figure 1 , Figure 2 and Figure 4 As shown, the microwave synthetic diamond production apparatus of the present invention includes a reaction vessel 10, a microwave emitting module and a microwave lens 13.

[0045] The reaction vessel 10 is a hollow body. It has a microwave window 11 for allowing external microwaves to penetrate into the vessel. Specifically, the microwave window 11 is located on the outer shell of the reaction vessel 10. The reaction vessel 10 also has a diamond stage 12 disposed within it. A focusing region 121 is defined on the top surface of the diamond stage 12.

[0046] A microwave transmitting module is located outside the reaction vessel 10 and emits circularly polarized microwaves toward the reaction vessel 10. The microwave transmitting module includes a mode conversion tube 21, a guide tube 22, a first waveguide 31, a first linearly polarized microwave source 32, a second waveguide 41, and a first matching load 43; and in this embodiment, it further includes a square-to-circular connecting tube 23, a connecting sleeve 24, a second linearly polarized microwave source 42, and a second matching load 33. The mode conversion tube 21, guide tube 22, first waveguide 31, and first linearly polarized microwave source 32 are sequentially connected along a microwave path.

[0047] Specifically, the microwave transmitting module of this embodiment has a microwave superposition component 20, a first microwave component 30 and a second microwave component 40. The first microwave component 30 and the second microwave component 40 emit linearly polarized microwaves toward the microwave superposition component 20. The microwaves emitted by the two microwave components 30 and 40 overlap in the microwave superposition component 20 and enter the reaction container 10 together.

[0048] Please refer to the following: Figures 2 to 4 As shown, the microwave superposition assembly 20 includes the aforementioned mode conversion tube 21, guide tube 22, square-to-round connecting tube 23, and connecting sleeve 24; the first microwave assembly 30 includes the aforementioned first waveguide 31, first linearly polarized microwave source 32, and second matching load 33; the second microwave assembly 40 includes the aforementioned second waveguide 41, second linearly polarized microwave source 42, and first matching load 43.

[0049] The aforementioned mode conversion tube 21 has a circular polarization opening 211 at each end (e.g., Figure 4 (As shown) and a linear polarization opening 212. The circular polarization opening 211 is located at the lower end of the mode switching tube 21 and faces the microwave viewing window 11 of the reaction vessel 10. The linear polarization opening 212 is located at the upper end of the mode switching tube 21. The mode switching tube 21 can convert linearly polarized microwaves into circularly polarized microwaves, or convert circularly polarized microwaves into linearly polarized microwaves, depending on the direction of microwave propagation.

[0050] Specifically, when external linearly polarized microwaves enter the upper mode conversion tube 21 through the linear polarization opening 212, the linearly polarized microwaves are converted into circularly polarized microwaves and emitted from the lower circularly polarized opening 211. When external circularly polarized microwaves enter the mode conversion tube 21 through the lower circularly polarized opening 211, the circularly polarized microwaves are converted into linearly polarized microwaves and emitted from the upper linearly polarized opening 212.

[0051] The aforementioned guide tube 22 has a main opening 221, a first opening 222, and a second opening 223. In this embodiment, the main opening 221 and the first opening 222 are located at the lower end and upper end of the guide tube 22, respectively. The main opening 221 is connected to the linear polarization opening 212 of the mode conversion tube 21. The second opening 223 is located on the tube wall of the guide tube 22, that is, the direction of the second opening 223 is not parallel to the direction of the first opening 222, and specifically, the direction of the second opening 223 is perpendicular to the direction of the first opening 222. The guide tube 22 is preferably a circular tube, that is, both the main opening 221 and the first opening 222 are circular.

[0052] The aforementioned square-to-round connecting pipe 23 is located at the upper end of the guide pipe 22 and connects to the first opening 222. The inner wall of the square-to-round connecting pipe 23 gradually changes from square to round, so that a square connecting opening 231 and a round connecting opening 232 are formed at both ends of the square-to-round connecting pipe 23. The round connecting opening 232 connects to the first opening 222 of the guide pipe 22.

[0053] Please refer to the following: Figure 2 , Figure 3 and Figure 5 As shown, the aforementioned connecting sleeve 24 is fitted over the guide tube 22. A conversion hole 241 is formed on the connecting sleeve 24, extending from the outer wall surface to the inner wall surface of the connecting sleeve 24. The conversion hole 241 is an elongated hole extending vertically, but its direction of extension is not limited to this. The opening of the conversion hole 241 on the inner wall surface connects to the second opening 223 of the guide tube 22, and the width of the conversion hole 241 gradually decreases towards the second opening 223. In this embodiment, the relative walls of the two holes of the conversion hole 241 are stepped, causing the width of the conversion hole 241 to gradually decrease in a stepped manner. In this embodiment, the connecting sleeve 24 and the guide tube 22 are integrally formed. However, in other preferred embodiments, the connecting sleeve 24 is a tube body independent of the guide tube 22 and is provided to the guide tube 22 by welding or other means.

[0054] Please refer to the following: Figures 2 to 4 As shown, the aforementioned first waveguide 31 is preferably a square tube, one end of which is connected to the square connection opening 231 of the square-to-round connecting tube 23. That is, the first waveguide 31 is connected to the first opening 222 of the guide tube 22 through the square-to-round connecting tube 23.

[0055] The other end of the first waveguide 31 is connected to the aforementioned first linearly polarized microwave source 32. The first linearly polarized microwave source 32 generates TE10 linearly polarized microwaves 81. After passing through the square-to-round connecting tube 23, the guide tube 22, and the mode conversion tube 21, the TE10 linearly polarized microwaves 81 are converted into TE11 circularly polarized mode microwaves 83 by the mode conversion tube 21 and emitted towards the microwave window 11 of the reaction vessel 10 through the circularly polarized opening 211 of the mode conversion tube 21.

[0056] The second matching load 33 is disposed on the first waveguide 31. Specifically, a circulator 34 is disposed on the first waveguide 31. When microwaves traveling in the opposite direction toward the first linearly polarized microwave source 32 appear in the first waveguide 31 (i.e., microwaves generated by the second linearly polarized microwave source 42 described later, which are reflected by the reaction vessel 10, pass through the mode conversion tube 21, and then through the guide tube 22 and the square-to-round connecting tube 23, they travel toward the first linearly polarized microwave source 32), the circulator 34 will guide the reverse microwaves to the second matching load 33 and convert the microwaves into heat energy at the second matching load 33, thereby protecting the first linearly polarized microwave source 32 from the influence of the reverse microwaves and eliminating useless microwave energy in the device.

[0057] The aforementioned second waveguide 41 is preferably a square tube, one end of which is connected to the opening of the conversion hole 241 of the connecting sleeve 24 on the outer wall surface. That is, the second waveguide 41 is connected to the second opening 223 of the guide tube 22 through the connecting sleeve 24. The other end of the second waveguide 41 is connected to the aforementioned second linearly polarized microwave source 42.

[0058] The second linearly polarized microwave source 42 generates TE10 linearly polarized microwaves 91. After passing through the guide tube 22 and the mode conversion tube 21, the TE10 linearly polarized microwaves 91 are converted into TE11 circularly polarized mode microwaves 93 by the mode conversion tube 21 and emitted towards the microwave window 11 of the reaction vessel 10 through the circularly polarized opening 211 of the mode conversion tube 21. In other preferred embodiments, the second linearly polarized microwave source 42 may be omitted as appropriate.

[0059] The aforementioned first matching load 43 is disposed on the second waveguide 41. Specifically, a circulator 44 is disposed on the second waveguide 41. When microwaves traveling in the opposite direction toward the second linearly polarized microwave source 42 appear in the second waveguide 41 (i.e., microwaves generated by the first linearly polarized microwave source 32 are reflected by the reaction vessel 10, and after passing through the mode conversion tube 21, they cannot pass through the square-to-round connecting tube 23 due to the electric field direction, but will travel toward the second linearly polarized microwave source 42 through the guide tube 22), the circulator 44 guides the reverse microwaves in the second waveguide 41 to the first matching load 43 to protect the second linearly polarized microwave source 42 and eliminate useless microwave energy in the device.

[0060] The aforementioned microwave lens 13 is disposed between the circularly polarized opening 211 of the mode conversion tube 21 of the microwave transmitting module and the diamond stage 12 of the reaction vessel 10. The microwave lens 13 focuses the circularly polarized microwaves emitted by the microwave transmitting module onto the focusing region 121 of the diamond stage 12. In this embodiment, the microwave lens 13 is disposed outside the reaction vessel 10 and is located between the circularly polarized opening 211 of the mode conversion tube 21 of the microwave transmitting module and the microwave viewing window 11 of the reaction vessel 10. The microwave lens 13 is preferably a dielectric convex lens, but appropriate combinations of other convex and concave lenses can also achieve the same similar microwave focusing effect.

[0061] In use, the diamond seed crystal A is placed in the focusing region 121 of the diamond stage 12. The first linearly polarized microwave source 32 generates TE10 linearly polarized microwaves 81 in the first waveguide 31. After entering the guide tube 22 via the square-to-round connecting tube 23, the TE10 linearly polarized microwaves 81 are converted into TE11 linearly polarized microwaves 82 in the guide tube 22. At the same time, the second linearly polarized microwave source 42 generates TE10 linearly polarized microwaves 91 in the second waveguide 41. After passing through the conversion hole 241 of the connecting sleeve 24, the TE10 linearly polarized microwaves 91 form TE11 linearly polarized microwaves 92 in the guide tube 22.

[0062] Finally, the TE11 linearly polarized microwave 82 originating from the first linearly polarized microwave source 32 and the TE11 linearly polarized microwave 92 originating from the second linearly polarized microwave source 42 pass downward through the mode conversion tube 21, and are respectively converted by the mode conversion tube 21 into TE11 circularly polarized mode microwave 83 and TE11 circularly polarized mode microwave 93. After being concentrated by the microwave lens 13, they pass through the microwave window 11 and are focused into the focusing area 121 to produce synthetic diamonds.

[0063] When microwaves 83 and 93 in TE11 circular polarization mode are reflected within the reaction vessel 10, the microwaves originating from the first linearly polarized microwave source 32 are reflected and enter the second waveguide 41 through the second opening 223, where they are ultimately consumed and converted into heat by the first matched load 43. Simultaneously, microwaves originating from the second linearly polarized microwave source 42 are reflected and enter the first waveguide 31 through the first opening 222, where they are ultimately consumed and converted into heat by the second matched load 33. The specific process is detailed below:

[0064] When the TE11 circularly polarized microwave 83 originating from the first linearly polarized microwave source 32 is reflected, the reflected TE11 circularly polarized microwave 83 passes upward through the mode conversion tube 21 and forms a TE11 linearly polarized microwave 82' within the guide tube 22. However, after the TE11 linearly polarized microwave 82' is converted twice by the mode conversion tube 21, its electric field angle will be perpendicular to the linearly polarized microwave TE11 linearly polarized microwave 82. Therefore, the TE11 linearly polarized microwave 82' cannot return to the first waveguide 31 from the first opening 222, but will enter the second waveguide 41 from the second opening 223 and be consumed by the first matched load 43 and converted into heat.

[0065] The situation is roughly the same when the TE11 circularly polarized microwave 93 originating from the second linearly polarized microwave source 42 is reflected. That is, the reflected TE11 circularly polarized microwave 93 will pass upward through the mode conversion tube 21 and form TE11 linearly polarized microwave 92' in the guide tube 22. Although the TE11 linearly polarized microwave 92' cannot return to the second waveguide 41, it can be consumed and converted into heat by the second matched load 33 through the first waveguide 31.

[0066] Another advantage of the present invention is that the microwave field distribution of the circularly polarized microwave mode is more uniform than that of the commonly used linearly polarized microwave mode. Furthermore, the present invention can simultaneously set up a first linearly polarized microwave source 32 and a second linearly polarized microwave source 42, and can also increase the growth rate of artificial diamonds on the stage by superimposing the circularly polarized microwave power generated by the two microwave sources.

[0067] Please refer to the following: Figures 6 to 9 As shown, the second embodiment of the present invention is largely the same as the first embodiment, except that the first opening 222A of the guide tube 22A is located on the tube wall of the guide tube 22A; in addition, the connecting sleeve 24A has two conversion holes 241A, wherein the two opposite openings of one conversion hole 241A are respectively connected to the first opening 222A of the guide tube 22A and the first waveguide 31A, and the two opposite openings of the other conversion hole 241A are respectively connected to the second opening 223A of the guide tube 22A and the second waveguide 41A.

[0068] In summary, by configuring a mode conversion tube 21, a guide tube 22, and a first matching load 43, this invention enables the conversion of TE11 circularly polarized microwaves 83 originating from the first linearly polarized microwave source 32 back into linearly polarized microwaves when these microwaves are reflected from the reaction vessel 10 due to impedance mismatch or other reasons. The reflected microwaves are then converted back into linearly polarized microwaves by the mode conversion tube 21 and emitted through the second opening 223 of the guide tube 22 to the first matching load 43, where they are converted into heat energy. This allows the invention to channel unwanted microwave energy from the reaction vessel 10, preventing the formation of complex multi-reflection standing waves, thereby maintaining the stability of the plasma spheres surrounding the diamond seed crystal A and improving diamond production efficiency.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A microwave synthetic diamond production apparatus, characterized in that, Include: A reaction vessel, which is a hollow body, has a microwave viewing window for allowing external microwaves to penetrate into the reaction vessel. The reaction vessel has... A diamond stage is disposed within the reaction vessel and defines a focusing region; A microwave transmitting module is disposed outside the reaction vessel and emits circularly polarized microwaves toward the microwave window of the reaction vessel. The microwave transmitting module includes a mode converter, a guide tube, a first waveguide, and a first linearly polarized microwave source connected in sequence. The microwave transmitting module also includes a second waveguide and a first matching load. The mode conversion tube has A circular polarization opening is located at one end of the mode conversion tube and faces the microwave window of the reaction vessel; A linear polarization opening is located at the other end of the mode switching tube. When external linearly polarized microwaves enter the mode switching tube through the linear polarization opening, the linearly polarized microwaves are converted into circularly polarized microwaves and emitted from the circularly polarized opening. When external circularly polarized microwaves enter the mode switching tube through the circularly polarized opening, the circularly polarized microwaves are converted into linearly polarized microwaves and emitted from the linearly polarized opening. The guide tube has the following features: A main opening is located at one end of the guide tube and is connected to the linear polarization opening of the mode conversion tube; The first thing to say; A second opening is located on the wall of the guide tube; the direction of the second opening is not parallel to the direction of the first opening; One end of the first waveguide is connected to the first opening of the waveguide, and the other end is connected to the first linearly polarized microwave source; The first linearly polarized microwave source generates linearly polarized microwaves, which are converted into circularly polarized microwaves by the mode conversion tube and emitted toward the microwave window of the reaction vessel through the circularly polarized opening of the mode conversion tube. One end of the second waveguide is connected to the second opening of the guide tube; The first matching load is located on the second waveguide; A microwave lens is disposed between the circular polarization opening of the mode conversion tube of the microwave transmitting module and the diamond stage of the reaction vessel; the microwave lens focuses the circularly polarized microwaves emitted by the microwave transmitting module onto the focusing area of ​​the diamond stage.

2. The microwave synthetic diamond production apparatus as described in claim 1, characterized in that, This microwave transmitting module has A second linearly polarized microwave source is disposed at the other end of the second waveguide; the second linearly polarized microwave source generates linearly polarized microwaves, which are converted into circularly polarized microwaves by the mode conversion tube and emitted toward the microwave window of the reaction vessel through the circularly polarized opening of the mode conversion tube. A second matching load is provided on the first waveguide.

3. The microwave synthetic diamond production apparatus as described in claim 1 or 2, characterized in that, The guide tube of the microwave transmitting module is a circular tube; The first waveguide and the second waveguide of the microwave transmitting module are square tubes.

4. The microwave synthetic diamond production apparatus as described in claim 3, characterized in that, The first opening of the guide tube is located at one end of the guide tube opposite to the main opening; The microwave transmitting module has a square-to-round connecting tube, which connects the first waveguide and the first opening of the guide tube; the inner wall of the square-to-round connecting tube gradually changes from square to round.

5. The microwave synthetic diamond production apparatus as described in claim 3, characterized in that, The first opening of the guide tube is located at one end of the guide tube opposite to the main opening; The microwave transmitting module has a connecting sleeve that is fitted over the guide tube, and the second waveguide is connected to the outer wall of the connecting sleeve; the connecting sleeve has... A conversion hole extends from the outer wall of the connecting sleeve to the inner wall and is an elongated hole; the two opposite openings of the conversion hole are respectively connected to the second opening of the guide tube and the second waveguide, and the width of the conversion hole gradually decreases towards the second opening.

6. The microwave synthetic diamond production apparatus as described in claim 5, characterized in that, The walls of the two holes of the conversion hole are stepped, so that the width of the conversion hole gradually narrows towards the second opening.

7. The microwave synthetic diamond production apparatus as described in claim 4, characterized in that, The microwave transmitting module has a connecting sleeve that is fitted over the guide tube, and the second waveguide is connected to the outer wall of the connecting sleeve; the connecting sleeve has... A conversion hole extends from the outer wall of the connecting sleeve to the inner wall and is an elongated hole; the two opposite openings of the conversion hole are respectively connected to the second opening of the guide tube and the second waveguide, and the width of the conversion hole gradually decreases towards the second opening.

8. The microwave synthetic diamond production apparatus as described in claim 7, characterized in that, The walls of the two holes of the conversion hole are stepped, so that the width of the conversion hole gradually narrows towards the second opening.

9. The microwave synthetic diamond production apparatus as described in claim 3, characterized in that, The first opening of the guide tube is located on the tube wall of the guide tube; The microwave transmitting module has a connecting sleeve that is fitted over the guide tube, and the second waveguide is connected to the outer wall of the connecting sleeve; the connecting sleeve has... Two conversion holes; each conversion hole extends from the outer wall surface of the connecting sleeve to the inner wall surface and is an elongated hole; the two opposite openings of one conversion hole are respectively connected to the first opening of the guide tube and the first waveguide; the two opposite openings of the other conversion hole are respectively connected to the second opening of the guide tube and the second waveguide; the width of each conversion hole gradually decreases towards the outer wall surface of the guide tube.

10. The microwave synthetic diamond production apparatus as described in claim 1 or 2, characterized in that, The opening direction of the first opening of the guide tube is perpendicular to the opening direction of the second opening.

Images