WO2011093545A1

WO2011093545A1 - Plasma generation device using electromagnetic waves and wave guide thereof

Info

Publication number: WO2011093545A1
Application number: PCT/KR2010/000615
Authority: WO
Inventors: 정태환
Original assignee: 주식회사 에스피에스
Priority date: 2010-01-29
Filing date: 2010-02-02
Publication date: 2011-08-04
Also published as: KR20110088658A

Abstract

The present invention relates to a plasma generation device using electromagnetic waves and a wave guide, and more specially, to a plasma generation device using electromagnetic waves, an atmospheric pressure plasma generation device in which high-density stable plasma can be generated regardless of a diameter of a dielectric tube by providing the dielectric tube which generates plasma in a taper part of the wave guide or in a first wave guide equipped in a higher position. According to the present invention, the atmospheric pressure plasma generation device using the electromagnetic waves comprises: the wave guide in which magnetron for oscillating the electromagnetic waves is provided; and the dielectric tube which is provided in the wave guide, and generates the plasma, wherein: the wave guide includes the first wave guide which has a first height, and the taper part which is equipped on an end of a body and is reduced as much as predetermined angles; and the dielectric tube is positioned in the taper part of the waveguide, in the first wave guide, or on the border between the taper part and the first wave guide. Since the volume and the height of the wave guide equipped with the dielectric tube from which the plasma is generated are large, the total strength of an electric field within the dielectric tube becomes strong. Further, it is possible to obtain larger plasma with high capacity and high density irrespective of the diameter of the dielectric tube.

Description

Plasma Generator Using Electromagnetic Wave and Waveguide for the Same

The present invention relates to a plasma generator using electromagnetic waves and a waveguide therefor, and more particularly, to an atmospheric pressure plasma generator and a waveguide capable of forming a large-capacity atmospheric plasma in a stable form.

When the temperature of a gaseous substance is continuously heated to raise its temperature, an aggregate of particles composed of an ion nucleus and free electrons is formed. This, together with the three forms of matter, solid, liquid, and gas, is called the 'fourth state of matter', and this state of matter is called plasma.

The plasma is generated as follows. Heat is applied to a solid with the lowest energy state of matter, and when the temperature rises, it becomes a liquid, and when heat energy is applied, it causes a transition to gas. Subsequently, when the gas receives more energy, ionized particles are produced that are different from the state transition, and the total number of charges of the cations and anions is about the same. This state is an electrically neutral plasma state.

This is a rare phenomenon on Earth, but in space, the steady state of almost all matter is plasma, and the sun's atmosphere is also filled with plasma. Plasma states that can be observed around us include fluorescent lamps used as lighting, neon signs commonly seen on the street, and lightning such as lightning that occurs frequently when showers occur. Aurora can also be regarded as light emitted by plasma.

The plasma can be used to synthesize artificial diamond, and surface treatment with plasma on the metal remains discovered in ancient historical sites can prevent wear and corrosion and improve the condition of the artifacts.

Plasma Display Panels (PDPs) using light emitted from plasma are widely used throughout the industry, and PDP TVs are a typical example. In addition, plasma can be used to replace fossil fuels such as petroleum and coal through nuclear fusion, and the world's major developed countries are actively researching to develop alternative energy sources using plasma.

In the modern industry, plasma is a high-tech material such as surface treatment of various materials, ion implantation, organic-inorganic film deposition and removal, cleaning operation, removal of toxic substances, sterilization, etc. It is used for various purposes in various fields ranging from environmental industry.

In addition, since plasma processing technology is much more advanced in precision than mechanical processing technology, it is important to be used as a core equipment for manufacturing products and parts in semiconductors, LCDs, and MEMS that require fine patterns.

It is known to produce plasma in vacuum or at atmospheric pressure.

The method of generating plasma in vacuum has many difficulties in practical application. Since the plasma is generated in a closed space in a vacuum, it is difficult to control the processing conditions in a material to be treated in an instant, and in a closed system, the processing is performed in a continuous process in which an article is moved. Has the disadvantage of being difficult.

There is a method of using an electromagnetic wave among the methods for generating a plasma at atmospheric pressure, which is known from the Patent No. 394994.

In the conventional plasma generator, as shown in FIGS. 1 to 3, the dielectric tube 12 and the 3-stub matching system 20 are arranged in the waveguide 18 so as to form a quarter interval of the intra-wavelength. When the magnetron 22 having the power supply system 24 oscillates the electromagnetic wave into the waveguide 18, it matches with the three-stub matching system 20 while supplying the maximum electric field in the dielectric tube 12 to generate plasma under atmospheric pressure. To be created.

The waveguide 18 is composed of a first waveguide, a tapered portion, and a low height portion as shown in FIG. The dielectric tube 12 is installed in the through hole 30 formed at the low height, and the magnetron 22 is installed in the insertion hole 32 formed in the first waveguide. And three stubs of the three-stub matching system 20 are installed outside the upper plate of the lower portion.

Between the end of the magnetron 22 and the waveguide 18, between the three stubs of the three-stub matching system 20, between the dielectric tube 12 and the adjacent stub, the tip of the dielectric tube 12 and the waveguide 18 The spacing of all is provided so that it is (lambda) g / 4.

The 3-stub matching system 20 is installed so that the spacing between the stubs is λg / 4 when the wavelength in the waveguide 18 is λg, so that the characteristic impedance of the waveguide 18 and the load impedance of the low height portion of the waveguide 18 are provided. It acts to transfer the maximum power to the load while matching. At this time, the electric field of the microwave generated by the magnetron 22 is maximized at the position where the dielectric tube 12 of the waveguide 18 is installed. At this time, the dielectric tube 12 is made of a quartz tube, and the inner wall thereof is coated with boron nitride 4 having high heat resistance, and is configured to withstand high temperature flames. When the torch gas 8 is supplied from the gas supply into the dielectric tube 12, the ignition device 14 supplies the initial electrons necessary for the discharge to discharge the dielectric tube 12. At this time, the plasma generated in the dielectric tube 12 by the electromagnetic wave having the maximum electric field is generated under atmospheric pressure, it is possible to generate the plasma at atmospheric pressure without a separate vacuum device. The plasma flame of high temperature (5000-6000 degreeC) is discharged through the torch exit of the dielectric tube 12.

Swirl gas (6) supplied to the dielectric pipe (12) together with the torch gas (8) is injected to have a spiral trajectory along the inner circumferential surface of the dielectric pipe to prevent overheating of the inner wall of the dielectric pipe by discharge heat, It collects the plasma flame discharged through the torch outlet.

However, arranging the dielectric tubes 12 at quarter intervals of the intra-wavelength of the waveguide 18 is merely a theory of rectangular waveguides. Depending on how the waveguide 18 is designed, spacing less than one quarter of the wavelength may be most efficient and may be optimized at spacings greater than one quarter. The general waveguide configuration of such an atmospheric pressure plasma generator is the same as that shown in FIG.

Referring to FIG. 1, first, the dielectric tube is inserted into a dielectric tube made of a ceramic, quartz tube, or the like at a point equal to 1/4 of the internal wavelength of the waveguide 18 to generate a plasma. However, in order to generate a plasma at atmospheric pressure conditions, a high-density electric field must be formed, unlike the plasma generating apparatus under vacuum conditions, the atmospheric pressure plasma achieves this through a narrower waveguide configuration. In this case, however, the dielectric tube must be provided in a narrow waveguide (particularly a waveguide having a low height in the case of a spherical waveguide) in which a high electric field is formed, so that plasma can be generated at atmospheric pressure.

However, the prior art has a problem that when the inner diameter of the dielectric tube 12 exceeds 27mm, the plasma is unstable and it is difficult to generate a large amount of plasma. Therefore, due to the low height and limited directness, the dielectric tube formed in the low height waveguide has its limitation in the internal volume for plasma generation, and as a result, the atmospheric pressure plasma has obvious limitations in terms of its capacity despite its high economy. There was.

Therefore, the first problem to be solved by the present invention is to provide a plasma apparatus capable of a larger capacity atmospheric pressure plasma by overcoming the limitation of the diameter of the dielectric tube that is recognized in the prior art.

In order to solve the above problems, the present invention is an atmospheric pressure plasma generating apparatus using an electromagnetic wave provided with a waveguide provided with a magnetron for oscillating electromagnetic waves, and a dielectric tube for generating plasma as installed in the waveguide, wherein the waveguide is made of A first waveguide having a height and a tapered portion provided at an end of the main body, the tapered portion being reduced by a predetermined angle, wherein the dielectric tube has a tapered portion of the waveguide, a first waveguide, or a tapered portion and a boundary between the first waveguide and the first waveguide. It provides an atmospheric pressure plasma generating apparatus characterized in that provided in.

In order to solve the above problems, the present invention also provides an atmospheric pressure plasma generating apparatus using an electromagnetic wave provided with a waveguide provided with a magnetron for oscillating electromagnetic waves, and a dielectric tube for generating plasma as installed in the waveguide. A first waveguide having a first height and a triangular shape or a ladder shape connected to an end of the first waveguide, wherein the dielectric tube is provided at a boundary with the triangular shape or the square shape or the first waveguide. An atmospheric pressure plasma generator is provided.

The tapered portion has a trapezoidal shape, and a second waveguide having a second height lower than the first height is provided at a rear end of the tapered portion, and the second waveguide is terminated before the λ / 4 point of the electromagnetic wave wavelength.

In one embodiment of the present invention, the dielectric tube is provided in the tapered portion, and the triangular portion or the ladder portion has a length shorter than λ / 4 of the electromagnetic wave wavelength. In addition, the end of the second waveguide has a shape that is not planar.

In order to solve the above problems, the present invention provides a waveguide for an atmospheric pressure plasma generator.

Since the plasma generator of the present invention has a large height and volume of the waveguide provided with the dielectric tube generating the plasma, the total intensity of the electric field in the dielectric tube is strong, and a larger and higher-capacity high density plasma is produced regardless of the diameter of the dielectric tube. It can achieve the effect of generating a stable and economical high temperature high density plasma without using a high power ignition device.

1 is a perspective view of a waveguide of a conventional plasma generator,

2 is a cross-sectional view of the dielectric tube installed in the waveguide of FIG.

3 is a circuit diagram of a magnetron and a power supply system installed in the waveguide of FIG. 1;

4 is a perspective view of a waveguide of one embodiment of a plasma generating device according to the present invention;

5 is a side view of the waveguide of FIG. 4;

6 and 7 are side views of a plate conduit of another embodiment of a plasma generating apparatus according to the present invention;

8 is three-dimensional coordinates for explaining variables a and b in the formula used to find the position of the dielectric tube in the waveguide where the electric field is maximum.

9 is a front view from above of various types of waveguides according to the present invention.

10 is a photograph of plasma generation in the dielectric tube according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 4 is a perspective view of a conduit tube and a dielectric tube, which are main components of the plasma generating apparatus, according to an embodiment of the present invention. FIG. 5 is a side view of the conduit tube of FIG.

4 and 5, in the embodiment, the waveguide includes a first waveguide 50a having a first height and a tapered portion 50b provided at one end of the first waveguide 50a and reduced at a predetermined angle. Include. In the prior art, the second end of the tapered portion 50 has a second waveguide having a height lower than the first height having a length of λ / 4 or more, and provided a dielectric tube at a point of λ / 4. When the second waveguide is not formed at the rear end of the tapered portion without forming such a complicated structure, or when the first waveguide is smaller than λ / 4, an electric field sufficient for generating an atmospheric pressure plasma has a larger volume of the tapered portion 50b or One point was found to occur in the waveguide 50a.

Therefore, the position of the dielectric tube in which the plasma is generated in the atmospheric pressure plasma generator according to the present invention is not the low height portion of the waveguide, but the taper portion 50b or the first waveguide 50a. That is, if sufficient atmospheric pressure is generated at the position, the volume of the waveguide and the dielectric tube penetrates also increases, thereby increasing the total capacity of the plasma.

In this case, when an electric field is applied to a larger volume waveguide (taper portion or first waveguide) to generate plasma, a dielectric tube may be installed in the waveguide having the volume condition. Compared with the above, it is possible to generate a large-capacity atmospheric plasma.

Referring to the operation principle of the plasma generating apparatus according to the above configuration of the present invention.

In the present invention, the dielectric tube 60 is provided in any one of the first waveguide 50a or the tapered portion 50b having a large volume as described above. However, the dielectric tube may be installed on the interface between the first waveguide and the tapered portion, and as long as it is provided in the waveguide having a volume larger than the second waveguide volume, it is not installed only in the second waveguide of low height as in the prior art. It belongs to the scope of the present invention. However, when a dielectric tube is formed only in a large volume waveguide, sufficient electric field required for plasma generation cannot be obtained, or even when plasma is generated, its intensity is very low and unstable. Accordingly, the present invention is connected to the other end of the tapered portion 50b so that the length of the second waveguide (lower height portion) having a lower height than the first waveguide (this is based on the direction in which the electric field is applied) within the waveguide. It is composed of less than one quarter of the electric wave wavelength lambda, so that a sufficient electric field is generated in the tapered portion or the first waveguide portion having a larger volume than the second waveguide, or the boundary region thereof. That is, according to the present invention, since the point of λ / 4 is formed at the low height of the waveguide, the length of the second waveguide portion is at least λ / 4 or more. However, even if the length of the second waveguide portion 50c is less than [lambda] / 4 even when the second waveguide portion constituting the second waveguide portion having an increased electric field density is present, even in a waveguide having a larger volume like the tapered portion 50b. An electric wave of a level required for plasma generation is applied, and this is applied to a large capacity of plasma.

4 shows an example in which the dielectric tube 60 is provided in the tapered portion 50b. Referring to FIG. 4, a through hole 51 having a dielectric tube is formed in the tapered portion 50b. A magnetron (not shown) for oscillating electromagnetic waves is provided in the first waveguide 50 (52 points) to apply an electric wave to the first waveguide. However, the point where the magnetron is provided does not need to be a λ / 4 point from the end of the waveguide as shown in FIG. 1, and may be located at various points. As described above, the present invention can generate the maximum atmospheric pressure plasma in various forms without limiting the position of the components, which will be described in detail below.

When the applied electric wave passes through the tapered portion 50b and is reflected at a length less than λ / 4, an electric field in which plasma can be formed is formed in the tapered portion 50b or the first waveguide 50a. At this time, the maximum electric field forming conditions can be freely configured according to the angle or length of the tapered portion (50b). .

The rear end of the tapered portion 50b may have various configurations as long as it is not a second waveguide configuration of lambda / 4 (electromagnetic wave wavelength) or more as in the prior art, and FIG. 5 shows a second waveguide having a short length (lower height than the first waveguide). The configuration is shown.

In particular, the length B of the tapered portion 50b and the length A of the second waveguide 50c having a low height can be freely selected, and must be limited to 1/4 times the wavelength of the electric field as in the prior art. There is no. For example, in the condition of 2.45 GHz, the tube wavelength is 21.34 cm, and the length of the taper portion and the second waveguide is n * 21.34, where n is a non-integer ratio and includes all ratios less than 1/4.

According to the present invention, in the case of the second waveguide in which the electric wave is applied and reflected, the length thereof is configured to be less than 1/4 of the wavelength of the electric field applied in the tube, thereby generating an electric field sufficient to generate plasma even at a taper of a larger volume. .

Therefore, the length of the waveguide portion can be freely selected without any particular limitation on the length condition of the waveguide portion as in the prior art.

Hereinafter, the method of deriving the maximum generation point of the electric field will be described in detail.

The position at which the electric field is maximized is derived from the three equations of Equation 1 derived from the Maxwell equation. At this time, it is possible to calculate the point where the electric field is maximized by adjusting the values of a and b.

[Revisions under Rule 91 20.05.2010]
Equation 1

Here, a and b are lengths on the x-axis and y-axis in the three-dimensional coordinates of FIG. 8, respectively.

The dielectric tube 60 may be made of quartz, ceramics, or the like, but the quartz tube was used in the present invention. Boron nitride (4) may be coated on the inner wall of the quartz tube as in the related art, but the boron nitride may not be coated when the quartz tube withstands high temperature with swirl gas flowing along the inner wall of the dielectric tube 60.

As described above, the larger the outer diameter of the dielectric tube 60, the weaker the electric field applied to the center of the dielectric tube 60 than the dielectric tube having the smaller outer diameter. However, in the case of the present invention, the dielectric tube 60 is located in the tapered portion 60 or the first waveguide 50a having a high height, and a sufficient electric field capable of forming a plasma is formed in the tapered portion or the first waveguide. Preferably, a dielectric tube is provided in the tapered portion where the electric field density is as high as possible, but the present invention is not limited thereto.

According to the present invention, the height and volume of the dielectric tube 60 included in the larger volume waveguide 50 can be increased, and as a result, the average electric field applied to the dielectric tube 60 becomes stronger. Therefore, even if the outer diameter of the dielectric tube 60 is increased, a stable large-capacity plasma can be generated.

6 and 7 are side views of the waveguide of another embodiment of the plasma generating apparatus according to the present invention, in which the second waveguide is not provided.

FIG. 6 shows a waveguide in which the tapered portions 50b form a triangle and the second height portion 50c is not provided. That is, in FIG. 6A, the tapered portion 50b forms a triangular portion, and its length (length in the direction in which the electric field is applied) should be less than 1/4 of the wavelength in the tube.

7 shows a waveguide in which the tapered portion 50b is a trapezoidal portion, and the tip height is a and there is no low height portion 50c. Even in this case, the trapezoidal portion should have a length less than 1/4 of the wavelength in the tube.

At this time, A, B, C indicating the length and a, b indicating the height are symbols indicating the internal length or height of the waveguide (see FIG. 8).

As described above, the waveguide of the present invention can be used in various forms.

The tip height of the tapered portion 50b may be 0 as shown in FIG. 6, or may be a non-zero as shown in FIG. 7, and thus may have a triangular or trapezoidal shape. Furthermore, the end of the waveguide is not only a general plane but also an end of various shapes. For example, curved shapes, triangular shapes, trapezoidal shapes, and the like are all possible, and the configuration of these various waveguide ends is disclosed in FIG. 9.

However, irrespective of the shape of the taper portion and the presence or absence of the second waveguide at the rear end of the taper portion, the length of the region in which the wavelength in the tube is integrated is less than 1/4 of the wavelength in the tube, and is provided in the largest volume of the region in which the dielectric tube is integrated. As long as they are installed, they all fall within the scope of the present invention.

9, a waveguide, that is, a second waveguide, according to an embodiment of the present invention may have a cross section of various non-planar surfaces such as a triangle, a curved surface, and a trapezoid. In this case, the electric field is integrated to a higher level. However, irrespective of the shape of the end portion, the second waveguide 50c has a length of less than 1 / 4λ, and the dielectric tube 60 is provided in the tapered portion 50b, which is also shown in FIG.

The dielectric tube is preferably a tapered portion, but the dielectric tube 60 may be a tapered portion 50b, a first waveguide 50a, or a tapered portion 50b regardless of the shape of the waveguide 50 including the tapered portion. ) At the boundary between the first waveguide 50a and the boundary between the tapered portion 50b and the second waveguide 50c (all of these cases have a larger area than the case where the dielectric waveguide is provided only in the second waveguide). Since the dielectric tube 60 is large in height and volume included in the waveguide 50, the intensity of the total electric field applied to the dielectric tube 60 increases, thereby generating a larger amount of plasma. As a result, the atmospheric pressure plasma can be generated even at a diameter of 27 mm or more, which is recognized as a limit value of the diameter of the dielectric tube in the prior art, which will be described in more detail in the following experimental example.

As a result, the electric discharge electric field of air is 30000 V / cm, and if a higher voltage is applied, plasma can be generated without an ignition device. If argon gas or helium gas is used, it can be discharged at a lower voltage. Therefore, it is easier to ignite using inert gas instead of air as torch gas.

When air is used as the swirl gas, plasma of 1 m or more can be generated. The temperature of plasma is 2000 degreeC or more.

Experimental Example 1

Experimental Example 1 is an experimental example when the dielectric tube 60 is located in the tapered portion 50b of the waveguide 50.

Shape of waveguide 50: first waveguide 50a: length C: 110 mm, height a + b: 34 mm

Taper portion 50b: length B: 76 mm, tip height a: 5 mm

Second waveguide 50c: length A: 5 mm, height a: 5 mm

Waveguide Width: 72.14mm

Distance from the tip of the lower portion of the waveguide to the center of the through hole 51: 69.85 mm

Diameter of the through hole 51: 50 mm

Outer diameter of dielectric tube: 50mm, inner diameter: 47mm, length: 1m, material: quartz tube

In this experimental example, the atmospheric pressure plasma was generated according to the configuration disclosed in FIG. 5, and in particular, the atmospheric pressure plasma was generated by a 50 mm dielectric tube corresponding to almost twice the diameter of the dielectric tube of 27 mm, which was recognized as a limitation in the prior art.

Magnetrons with 1kW and 1.2kW capacities were used, and air, oxygen, argon, helium, and nitrogen were used as torch gases. The experiment was then controlled from 7 to 20 lpm (increase flow rate or reduce power if arcing occurs). In addition, the swirl gas does not necessarily use air, and other gases (O ₂ , N ₂ , and H ₂ depending on the purpose of the experiment) were used regardless of the type if necessary.

This experiment confirmed that a stable and economical high density plasma was generated, which is shown in FIG. In particular, in the present experimental example, a UV lamp was used without a separate ignition device applying high power for generating the plasma. Due to the increased total electric field strength, the ignition was possible only with the UV lamp.

Experimental Example 2

In this experimental example, the dielectric tube exists at the interface between the first waveguide and the taper portion, except that the distance from the end of the second waveguide (low height portion) to the center of the through hole provided with the dielectric tube is 78 mm. Same as Example 1. In this Experimental Example, the intensity of the electric field was weaker than that of Experimental Example 1. In addition, the temperature and density of the plasma generated by the weakness of the electric field weakened somewhat. However, plasma was also generated in the present experimental example, and it can be seen that sufficient atmospheric pressure plasma can be generated even with a wider dielectric tube than the prior art.

Comparative Experimental Example 1

In the atmospheric pressure plasma generator having a second waveguide having a length of 1 / 4λ or more, as in the prior art, a narrow diameter (25 mm) dielectric tube according to the prior art is installed in a tapered portion, and then plasma is generated under the same conditions as in Experiment 1. However, the atmospheric pressure plasma was not sufficiently formed.

Therefore, it is fully demonstrated from the above experimental results that the waveguide and the dielectric tube configuration according to the present invention can form a large-capacity stable plasma in a larger diameter dielectric tube.

Although the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various changes or modifications can be made within the spirit and scope of the invention, and such changes or modifications are consequently claimed. You will have to belong to the range.

Claims

In the atmospheric pressure plasma generator using an electromagnetic wave provided with a waveguide provided with a magnetron for oscillating electromagnetic waves, and a dielectric tube provided in the waveguide to generate plasma,

The waveguide includes a first waveguide having a first height and a tapered portion provided at an end of the main body and reduced by a predetermined angle.

The dielectric tube is an atmospheric pressure plasma generator, characterized in that provided on the boundary of the tapered portion, the first waveguide, or the tapered portion and the first waveguide of the waveguide.
In the atmospheric pressure plasma generator using an electromagnetic wave provided with a waveguide provided with a magnetron for oscillating electromagnetic waves, and a dielectric tube provided in the waveguide to generate plasma,

The waveguide includes a first waveguide having a first height and a triangular shape or a ladder shape connected to an end of the first waveguide, wherein the dielectric tube is at a boundary with the triangular shape or the square shape or the first waveguide. Atmospheric pressure plasma generator, characterized in that provided.
The method of claim 1,

The atmospheric pressure plasma generator, characterized in that the tapered portion has a trapezoid.
The method of claim 1,

A second waveguide having a second height lower than the first height is provided at the rear end of the tapered portion, wherein the second waveguide is terminated before the λ / 4 point of the electromagnetic wave wavelength.
The method of claim 4, wherein

The dielectric tube is an atmospheric pressure plasma generator, characterized in that provided in the tapered portion.
The method of claim 2,

The triangular portion or ladder portion has a length of less than λ / 4 of the electromagnetic wave wavelength, the atmospheric pressure plasma generating apparatus.
The method of claim 4, wherein

An end portion of the second waveguide is an atmospheric pressure plasma generator, characterized in that the non-planar shape.
A waveguide for an atmospheric pressure plasma generator according to any one of claims 1, 3 to 5 or 7.