JP2005123034A - Plasma generating electrode and plasma reactor - Google Patents

Abstract

A plasma generating electrode capable of generating a stable and uniform plasma with high efficiency is provided.
Two or more plate-like unit electrodes 2 facing each other, and a surface 7 having a length corresponding to the length in the longitudinal direction of both end portions 6 of the unit electrode 2 and facing each other, A plasma generating electrode 1 including one or more sets of holding members 5 that hold the unit electrode 2 at a predetermined interval by being sandwiched between both end portions 6 of the unit electrode 2, and each unit is opposed to each other. At least one of the electrodes 2 includes a ceramic body 3 serving as a dielectric and a conductive film 4 disposed inside the ceramic body 3, and a pair of holding members 5 are on one surface 7 facing each other. Furthermore, the plasma generating electrode 1 having a groove 8 extending in the longitudinal direction of one surface 7 over the entire length.
[Selection] Figure 1

Description

The present invention relates to a plasma generating electrode and a plasma reactor. More specifically, the present invention relates to a plasma generating electrode and a plasma reactor capable of generating a stable and uniform plasma with high efficiency.

Silent discharge occurs when a dielectric is placed between two fixed electrodes and a high voltage alternating current or periodic pulse voltage is applied. In the resulting plasma field, active species, radicals, and ions are generated. It is known that gas reaction and decomposition are promoted, and it is known that this can be used to remove harmful components contained in exhaust gas discharged from engines and various incinerators.

For example, by passing exhaust gas discharged from an engine or various incinerators through the plasma field, for example, plasma that treats NO _x , carbon particulates, HC, CO, etc. contained in the exhaust gas A plasma reactor using a generation electrode is disclosed (for example, see Patent Document 1).
JP 2001-164925 A

However, the plasma generating electrode used in such a plasma reactor has a problem that stable and uniform plasma cannot be generated with high efficiency. In particular, creeping discharge occurs along the inner surface of the holding member for holding both ends of each electrode, and stable plasma cannot be efficiently generated between the opposing electrodes.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a plasma generating electrode and a plasma reactor capable of generating a stable and uniform plasma with high efficiency.

In order to achieve the above object, the present invention provides the following plasma generating electrode and plasma reactor.

[1] Two or more plate-like unit electrodes facing each other, and having a length corresponding to the length in the longitudinal direction of both end portions of the unit electrode and having one surface facing each other, And a pair of holding members that hold the unit electrodes so as to form a space between the unit electrodes at a predetermined interval by being sandwiched between both ends, and voltage between the unit electrodes. A plasma generating electrode capable of generating plasma by applying at least one of the unit electrodes facing each other, a ceramic body serving as a dielectric, and a conductive body disposed within the ceramic body And a pair of holding members having a groove extending over the entire length in the longitudinal direction of the one surface on the one surface facing each other. The pole.

[2] The plasma generating electrode according to [1], wherein the concave groove is composed of two or more planes or one or more curved surfaces, or one or more planes and one or more curved surfaces.

[3] The plasma generating electrode according to [1] or [2], wherein a shape of a cross section perpendicular to the longitudinal direction of the concave groove is a quadrilateral or more polygonal shape, a semicircular shape, a semielliptical shape, or a bullet shape.

[4] When the shape of the cross section perpendicular to the longitudinal direction of the concave groove is a quadrilateral or more polygon, the one surface of the holding member, the surface of the concave groove, and the concave groove in the cross section. The plasma generating electrode according to any one of [1] to [3], wherein the space side angle is 90 to 270 degrees.

[5] The overall length including the concave groove on the one surface of the holding member in a cross section perpendicular to the longitudinal direction of the holding member is 1.3 to 10 times the width of the one surface of the holding member. The plasma generating electrode according to any one of [1] to [4].

[6] The space-side angle formed by the one surface of the holding member and the surface of the unit electrode in a cross section perpendicular to the longitudinal direction of the holding member is 90 degrees or more. The plasma generating electrode according to any one of [1] to [5].

[7] The above [1] to [6], wherein the holding member contains at least one compound selected from the group consisting of aluminum oxide, magnesium oxide, silicon oxide, silicon nitride, zirconia, mullite, cordierite, and crystallized glass. ] The plasma generating electrode in any one of.

[8] The ceramic body is made of aluminum oxide, magnesium oxide, silicon oxide, silicon nitride, aluminum nitride, mullite, cordierite, magnesium-calcium-titanium oxide, barium-titanium-zinc oxide, and barium-titanium. The plasma generating electrode according to any one of [1] to [7], which contains at least one compound selected from the group consisting of a system oxide.

[9] The [1] to [1], wherein the conductive film contains at least one metal selected from the group consisting of tungsten, molybdenum, manganese, chromium, titanium, zirconia, nickel, iron, silver, copper, platinum, and palladium. 8] The plasma generating electrode according to any one of the above.

[10] The plasma generating electrode according to any one of [1] to [9], and a case body having a gas flow path (gas flow path) containing a predetermined component therein, wherein the gas is A plasma reactor capable of causing the predetermined component contained in the gas to react with plasma generated by the plasma generating electrode when introduced into the gas flow path of the case body.

[11] The plasma reactor according to [10], further including a pulse power source for applying a voltage to the plasma generating electrode.

[12] The plasma reactor according to [11], wherein the pulse power source includes at least one SI thyristor therein.

The plastic plasma generating electrode of the present invention can generate stable and uniform plasma with high efficiency. In addition, since the plasma reactor of the present invention includes such a plasma generation electrode, energy saving can be realized and reaction efficiency can be improved.

Hereinafter, embodiments of a plasma generating electrode and a plasma reactor according to the present invention will be described in detail with reference to the drawings. However, the present invention is not construed as being limited thereto, and the scope of the present invention is not limited thereto. Various changes, modifications, and improvements can be made based on the knowledge of those skilled in the art without departing from the scope.

FIG. 1 is a cross-sectional view showing a cross section perpendicular to the longitudinal direction of both end portions of a unit electrode in one embodiment of the plasma generating electrode of the present invention. FIG. 2 is a perspective view showing an example of a holding member constituting the plasma generating electrode of the present embodiment. FIG. 3 is an enlarged view of the plasma generating electrode holding member shown in FIG.

As shown in FIGS. 1 to 3, the plasma generating electrode 1 according to the present embodiment corresponds to the length in the longitudinal direction of two or more plate-like unit electrodes 2 facing each other and both end portions 6 of the unit electrode 2. And having one surface 7 facing each other and being sandwiched between both end portions 6 of the unit electrode 2, the unit electrodes 2 are separated from each other by a predetermined interval, and a space 14 is formed therebetween. A plasma generating electrode 1 that includes one or more sets of holding members 5 that are held so as to be formed, and is capable of generating plasma by applying a voltage between the unit electrodes 2. 2 (both in FIG. 1) have a ceramic body 3 as a dielectric and a conductive film 4 disposed inside the ceramic body 3, and a set of holding members 5 are mutually connected. On one opposing surface 7, In the longitudinal direction of the surface 7 of, and has a groove 8 which extends over its entire length.

As described above, the unit electrode 2 used in the plasma generating electrode 1 of the present embodiment is a so-called barrier discharge type electrode having a ceramic body 3 and a conductive film 4 as a dielectric. Compared with the case where the discharge is performed alone, it is possible to reduce the offset discharge such as a spark and to cause a small discharge between the unit electrodes 2 at a plurality of locations. Such a plurality of small discharges can reduce power consumption because less current flows compared to sparks and other discharges. Furthermore, due to the presence of a dielectric, the discharge occurs before the start of ion movement. It stops, electron movement is dominant between the unit electrodes 2, and non-thermal plasma without temperature rise can be generated. The plasma generating electrode 1 of the present embodiment purifies ozone by reacting oxygen contained in a plasma reactor that reacts with a gas containing a predetermined component, for example, an exhaust gas treatment device that treats exhaust gas or air. It can be used for an ozonizer or the like.

Further, in the present embodiment, one or more sets of holding members 5 holding the unit electrode 2 are disposed on one surface 7 facing each other over the entire length in the longitudinal direction of the one surface 7. Since the groove 8 is extended, it is possible to effectively prevent the creeping discharge that occurs via the one surface 7 of the holding member 5 when performing the above-described discharge, and the unit electrode A stable and uniform plasma can be generated between the two. As shown in FIG. 4A, when one surface 37 of the holding member 35 constituting the plasma generating electrode 31 is flat, not only the stable and uniform plasma cannot be generated, but also the unit electrodes 32 are mutually connected. When a voltage is applied between them, a creeping discharge 39 occurs along one surface 37 of the holding member 35, so that its energy efficiency is lowered. As shown in FIG. 4B, such creeping discharge 39 causes the outer edge portion 38 of the conductive film 34 disposed inside the unit electrode 32 to be closer to the space side (inner side than the one surface 37 of the holding member 35. ) Is disposed in the ceramic body 33 in a state of being located)), but if configured in this way, the ratio of the area of the portion capable of generating plasma to the area of the entire surface of the unit electrode 32 As a result, the plasma generating electrode 31 is undesirably enlarged. As shown in FIG. 1, in the present embodiment, the outer edge portion of the conductive film 4 disposed inside the unit electrode 2 is substantially at the same position as the one surface 7 of the holding member 5 or from the one surface 7. Even in a configuration that is located on the outside (in FIG. 1, located on the outside of the one surface 7 of the holding member 5), it is possible to effectively prevent creeping discharge that occurs on the one surface 7 of the holding member 5. Thus, plasma can be effectively generated from the entire area of the unit electrode 2 excluding the portion held by the holding member 5.

In the holding member 5 used in the present embodiment, the concave groove 8 is preferably composed of two or more planes or one or more curved surfaces, or one or more planes and one or more curved surfaces. Further, the shape of the cross section perpendicular to the longitudinal direction of the concave groove 8 is not particularly limited, but a U-shape (square) as shown in FIG. 2, an ellipse as shown in FIG. Or a semicircular shape in which the surface 9 of the concave groove 8 and the one surface 7 of the holding member 5 are formed as a continuous curved surface. As a suitable example, a polygonal shape, a bullet shape, or the like can be given. By setting it as such a cross-sectional shape, the creeping discharge which arises along the one surface 7 of the holding member 5 can be prevented effectively. In the following description of the present embodiment, “the cross section of the concave groove” simply means “a cross section perpendicular to the longitudinal direction of the concave groove”. Further, as shown in FIG. 7, the holding member 5 used in the present embodiment is configured such that one surface 7 of the holding member 5 and the surface 9 of the concave groove 8 are formed of a continuous or discontinuous curved surface. There may be.

Moreover, as shown in FIGS. 1-3, in the plasma generating electrode 1 of this Embodiment, the shape of the cross section perpendicular | vertical to the longitudinal direction of the ditch | groove 8 is a polygon more than a square (in FIGS. 1-3). In the cross section, the angle A on the space 14 side constituted by one surface 7 of the holding member 5, the surface 9 of the concave groove 8, and the surfaces 9 of the concave groove 8 is 90 to 90. It is preferably 270 degrees. When the angle A on the space 14 side constituted by one surface 7 of the holding member 5, the surface 9 of the groove 8, and the surfaces 9 of the groove 8 is less than 90 degrees or exceeds 270 degrees, the angle There is a possibility that the plasma is not generated effectively due to the concentration of the discharge. Further, for example, as shown in FIG. 5, when the surface 9 of the concave groove 8 is formed of a curved surface, one surface 7 of the holding member 5 and the surface 9 of the concave groove 8 formed of a curved surface It is preferable that the angle A on the space 14 side constituted by the tangent line at the contact point is 90 to 270 degrees. Moreover, although illustration is abbreviate | omitted, when one surface of a holding member is comprised from a curved surface, it is preferable similarly that the angle by the side of the space comprised by the tangent is 90-270 degree | times. Furthermore, in the case where one surface of the holding member is composed of two or more planes, the angle on the space side constituted by the surfaces of the holding member in a cross section perpendicular to the longitudinal direction of the holding member Is preferably 90 to 270 degrees.

In the present embodiment, as shown in FIGS. 1 and 3, the entire length L including the concave groove 8 of one surface 7 of the holding member in the cross section perpendicular to the longitudinal direction of the holding member 5 is It is preferably 1.3 to 10 times, more preferably 2 to 5 times, the width D of one surface (the length corresponding to the distance between the opposing unit electrodes 2). Note that the total length L including the concave groove 8 on the one surface 7 of the holding member 5 is, for example, as shown in FIG. 3, when the concave groove 8 has a U-shaped (square) cross section. This is the length of the portion indicated by the wavy line corresponding to the side and bottom surfaces of the groove 8 and the top surface (the one surface 7) (hereinafter, simply referred to as “the total length of one surface”). If the total length L of the one surface 7 of the holding member is smaller than 1.3 times the width D of the one surface 7 of the holding member 5, a sufficient creeping distance may not be ensured. If the total length L of the one surface 7 of the holding member 5 is larger than 10 times the width D of the one surface 7 of the holding member 5, abnormal discharge does not occur, but the space 14 formed by the holding member 5 is Since it becomes large, reaction efficiency may fall. When the cross-sectional shape of the concave groove is a semicircular shape, a semielliptical shape, or the like, the total length of one surface of the holding member is the sum of the arc length and the straight portions on both sides.

In addition, as shown in FIGS. 1 to 3, in the plasma generating electrode 1 of the present embodiment, the angle on the space 14 side constituted by one surface 7 of the holding member 5 and the surface of the unit electrode 2. B is preferably 90 degrees or more. With this configuration, abnormal discharge can be suppressed at the interface between the unit electrode 2 and the holding member 5.

Moreover, as shown in FIG. 8, the angle on the holding member 5 side constituted by the holding member 5 and the unit electrode 2 is 90 degrees or more, and the angle on the space 14 side is 90 degrees or more. Highly stable discharge space can be obtained.

As shown in FIG. 3, the holding member 5 used in the plasma generating electrode 1 of the present embodiment can hold both end portions 6 well with the unit electrodes 2 spaced apart from each other by a predetermined distance. Preferably, the holding member 5 is selected from the group consisting of aluminum oxide, magnesium oxide, silicon oxide, silicon nitride, zirconia, mullite, cordierite, and crystallized glass. It preferably comprises at least one compound. Moreover, since the holding member 5 holds the unit electrode 2 to which a voltage is applied, it preferably has electrical insulation. Specifically, the dielectric breakdown voltage of the holding member 5 is preferably 5 kV / mm or more.

The shape of the surface other than the one surface 7 of the holding member 5, the width D of the one surface, and the like can be appropriately selected and determined according to the unit electrode 2 used. For example, the width D of the one surface 7 of the holding member 5 corresponds to the interval between the opposing unit electrodes 2 and can be determined by the required plasma intensity, the power source that applies the voltage, or the like. preferable. Specifically, for example, when the plasma generating electrode 1 is used to convert NO _{x in} the exhaust gas to NO ₂ , the width D of one surface of the holding member may be set to 0.3 to 2.0 mm. preferable.

The material of the ceramic body 3 constituting the unit electrode 2 is not particularly limited as long as it can be suitably used as a dielectric. For example, the ceramic body 3 is made of aluminum oxide or magnesium oxide. At least one compound selected from the group consisting of silicon oxide, silicon nitride, aluminum nitride, mullite, cordierite, magnesium-calcium-titanium oxide, barium-titanium-zinc oxide, and barium-titanium oxide It is preferable to contain. By including such a compound, the ceramic body 3 excellent in thermal shock resistance can be obtained. The ceramic body 3 used in the present embodiment can be formed using, for example, a tape-shaped ceramic green sheet or a sheet obtained by extrusion molding. It can also be formed using a flat plate produced by a powder dry press. In addition, the magnitude | size of the ceramic body 3 is not specifically limited, According to the intended purpose, it can determine suitably.

The conductive film 4 constituting the unit electrode 2 is not particularly limited as long as it can generate plasma by applying a voltage between the unit electrodes 2. 4 preferably contains at least one metal selected from the group consisting of tungsten, molybdenum, manganese, chromium, titanium, zirconia, nickel, iron, silver, copper, platinum, and palladium.

Further, the method for disposing the conductive film 4 is not particularly limited, but it is preferable that the conductive film 4 is formed and disposed by coating the ceramic body 3. Specific examples of suitable methods include screen printing, calendar roll, spray, electrostatic coating, dip, knife coater, chemical vapor deposition, physical vapor deposition, and the like. According to such a method, the conductive film 4 having excellent surface smoothness and a small thickness can be easily formed.

The thicknesses of the ceramic body 3 and the conductive film 4 are appropriately determined in consideration of the magnitude and strength of the plasma to be generated, the voltage applied to the unit electrode 2, and the like.

In addition, when discharging by applying a voltage between the unit electrodes 2, it is necessary to apply a voltage directly to the conductive film 4, so that the unit electrode 2 has either one of the end portions 6. In this case, it is preferable that a predetermined power source (not shown) and the conductive film 4 be energized. In FIG. 1, the unit electrodes 2 are configured to be alternately energized at the end portions 6 on different sides.

Further, in the plasma generating electrode 1 shown in FIG. 1, all the unit electrodes 2 have a ceramic body 3 serving as a dielectric, and a conductive film 4 disposed inside the ceramic body 3. In the present embodiment, it is only necessary that at least one unit electrode 2 has a ceramic body 3 and a conductive film 4. For example, as shown in FIG. 9, one unit electrode constituting the plasma generating electrode 1. 2a may include the ceramic body 3 and the conductive film 4, and the other unit electrode 2b may be composed of a plate electrode having simple conductivity. In this case, the configuration of the other unit electrode 2b is not particularly limited, but a conventionally known electrode, for example, a plate-like electrode formed of a conductive metal can be suitably used. 1 and 9 show the plasma generating electrode 1 composed of eight unit electrodes 2, the number of unit electrodes 2 is not limited to this. In FIG. 9, the same components as those in the plasma generating electrode 1 shown in FIG.

Hereinafter, the manufacturing method of the plasma generating electrode of this Embodiment is demonstrated concretely.

First, a slurry for forming a tape-shaped ceramic green sheet to be a ceramic body constituting the plasma generating electrode (ceramic green sheet working slurry) is prepared. This slurry is prepared by blending an appropriate binder, a sintering aid, a plasticizer, a dispersant, an organic solvent and the like with a predetermined ceramic powder. Although it does not specifically limit as ceramic powder mentioned above, For example, powders, such as an alumina, mullite, cordierite, silicon nitride, aluminum nitride, can be used conveniently. The sintering aid is preferably added in an amount of 3 to 10 parts by mass with respect to 100 parts by mass of the ceramic powder. The plasticizer, dispersant and organic solvent are used to form a conventionally known ceramic green sheet. Plasticizers, dispersants and organic solvents used in the resulting slurry can be suitably used. The ceramic green sheet working slurry may be in the form of a paste.

Next, the obtained ceramic green sheet working slurry is molded to have a predetermined thickness according to a conventionally known technique such as a doctor blade method, a calendar method, a printing method, a reverse roll coater method, etc. Form. The ceramic green sheets formed in this way are processed as cutting, cutting, punching, formation of communication holes, etc., or as an integrated laminate by thermocompression bonding or the like with a plurality of ceramic green sheets laminated. It may be used.

On the other hand, a conductor paste for forming a conductive film is prepared. This conductor paste can be obtained, for example, by adding a solvent such as binder and terpineol to molybdenum powder and kneading sufficiently using a triroll mill. In addition, you may add an additive to a conductor paste as needed in order to improve adhesiveness and sintering property with the ceramic green sheet mentioned above.

The conductive paste thus obtained is printed on the surface of the ceramic green sheet using screen printing or the like to form a conductive film having a predetermined shape.

Next, a ceramic green sheet on which a conductive film is printed and a ceramic green sheet different from this are laminated so as to cover the printed conductive film, thereby obtaining a ceramic green sheet in which the conductive film is disposed. When laminating the ceramic green sheets, it is preferable to laminate while pressing at a temperature of 100 ° C. and a pressure of 10 MPa.

Next, a ceramic green sheet having a conductive film disposed therein is fired to form unit electrodes. In this way, the necessary number of unit electrodes are formed for the plasma generating electrode.

Separately, a holding member for holding both end portions of the unit electrode is manufactured. Specifically, for example, a mixed powder of alumina powder and organic binder is subjected to die press molding, binder calcination, and main firing, and the length corresponding to the length in the longitudinal direction of both end portions of the unit electrode is set. One or more holding members are formed. After that, on one surface of the holding member, a concave groove extending in the longitudinal direction of the one surface over the entire length is formed by grinding or the like. Note that the concave groove of the holding member is not formed by grinding or the like as described above, but may be formed by molding a mixed powder as a raw material by die press molding.

Next, using the holding member thus obtained, a plasma generating electrode is manufactured by holding a predetermined number of unit electrodes at predetermined intervals. At this time, an electrode having a ceramic body and a conductor manufactured by the above-described method may be used for all of the unit electrodes facing each other, and such an electrode is only one of the unit electrodes facing each other, A conventionally known electrode such as a metal plate may be used as the electrode. Note that the method of manufacturing the plasma generating electrode of the present embodiment is not limited to the above method.

Next, an embodiment of the plasma reactor of the present invention will be specifically described. 10A is a cross-sectional view of one embodiment of the plasma reactor of the present invention cut along a plane including the gas flow direction, and FIG. 10B is a cross-sectional view taken along line AA in FIG. It is sectional drawing in a line.

As shown in FIGS. 10 (a) and 10 (b), the plasma reactor 11 of the present embodiment is one embodiment of the plasma generating electrode of the present invention (plasma generating electrode) as shown in FIG. 1) and a case body 12 having a gas flow path (gas flow path 13) containing a predetermined component therein, and plasma is generated when the gas is introduced into the gas flow path 13 of the case body 12. Predetermined components contained in the gas can react with the plasma generated by the electrode 1. The plasma reactor 11 of the present embodiment can be suitably used for an exhaust gas treatment device, an ozonizer for purifying ozone by reacting oxygen contained in air or the like. In particular, as described above, the plasma generating electrode 1 includes one or more sets of holding members 5 having the concave grooves 8 on one surface facing each other. Creeping discharge along the surface of the plasma reactor 11 is effectively prevented, energy saving of the plasma reactor 11 can be realized, and reaction efficiency can be improved.

The material of the case body 12 constituting the plasma reactor 11 according to the present embodiment is not particularly limited. For example, the ferrite body has excellent conductivity, is light and inexpensive, and has little deformation due to thermal expansion. Stainless steel or the like is preferable.

Although not shown, the plasma reactor of the present embodiment may further include a power source for applying a voltage to the plasma generating electrode. As this power source, a conventionally known power source can be suitably used as long as it can supply a current capable of effectively generating plasma. The power source described above is preferably a pulse power source, and more preferably, the power source has at least one SI thyristor therein. By using such a power source, plasma can be generated more efficiently.

In addition, the plasma reactor according to the present embodiment may be configured to supply current from an external power source instead of the configuration including the power source as described above.

The current supplied to the plasma generating electrode constituting the plasma reactor can be selected and determined as appropriate depending on the intensity of the plasma to be generated. For example, when the plasma reactor is installed in the exhaust system of an automobile, the current supplied to the plasma generating electrode is a direct current with a voltage of 1 kV or more, a peak voltage of 1 kV or more, and the number of pulses per second is 100 or more. A pulse current that is (100 Hz or more), an alternating current that has a peak voltage of 1 kV or more and a frequency of 100 or more (100 Hz or more), or a current obtained by superimposing any two of these is preferable. With this configuration, plasma can be generated efficiently.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Example 1)
A plasma generating electrode comprising thirty plate-shaped unit electrodes facing each other and a holding member that is held between both end portions of the unit electrode to hold the unit electrodes at a predetermined interval. Manufactured. The unit electrode constituting the plasma generating electrode has a ceramic body serving as a dielectric, and a conductive film disposed inside the ceramic body.

The ceramic body constituting the unit electrode is formed using a ceramic green sheet containing alumina. In the present embodiment, as shown in FIG. 11, the surface shape of the ceramic body 3 is a rectangle having a length of 90 mm and a width of 50 mm. The thickness was 1 mm. In addition, the conductive film 4 was formed by printing inside a substantially central portion of the ceramic body 3 using a paste containing tungsten. The size of the conductive film 4 was 84 mm in length, 45 mm in width, and 10 μm in thickness. The longitudinal end portions 6 of the ceramic body 3 each have a portion where the conductive film 4 is not disposed by 3 mm.

The holding member 5 has a width D of one surface 7 of 1 mm, the length of the portion holding the end 6 of the unit electrode 2 in the longitudinal direction is 50 mm, and the length in the short direction is 5 mm. The holding member 5 is provided with a semi-elliptical concave groove 8 whose cross-sectional shape is 2 mm deep from the one surface 7 in the longitudinal direction of the one surface 7 over the entire length. Set up.

A plasma reactor (reactor) was manufactured by arranging such a plasma generating electrode inside a predetermined case body. A power source having an SI thyristor was connected to the plasma reactor, and plasma was generated under conditions of 2 kHz, 6 kV, and 50 mJ / pulse. A uniform discharge was generated on the entire surface of the unit electrode, and a stable plasma could be generated.

(Comparative Example 1)
As shown in FIG. 12, the holding member 35 has one surface 37 that is flat, the width of one surface 37 of the holding member 35 is 1 mm, and the length in the longitudinal direction of the portion that holds the end 36 of the unit electrode 32. The plasma generating electrode 31 is manufactured in the same manner as in Example 1 except that the length in the short direction is 3 mm, and a plasma reactor (not shown) is manufactured using the plasma generating electrode 31. Manufactured.

When the same power source as that used in Example 1 was connected to this plasma reactor and plasma was generated under conditions of 2 kHz and 5 kV, creeping discharge occurred on one surface of the holding member. In order to generate plasma without causing creeping discharge, 6.5 kV, 60 mJ / pulse of higher energy was required as compared with Example 1.

(Comparative Example 2)
As shown in FIG. 13, the plasma generating electrode 31 configured in the same manner as in Comparative Example 1 except that the conductive film 34 of the unit electrode 32 constituting the plasma generating electrode 31 is 80 mm long, 45 mm wide, and 10 μm thick. A plasma reactor (not shown) was manufactured using the plasma generating electrode 31. In the plasma generating electrode 31 used in Comparative Example 2, the distance between one surface 37 of the holding member 35 and the outer edge portion 38 of the conductive film 34 is 2 mm.

When the same power source as that used in Example 1 was connected to this plasma reactor and plasma was generated under the conditions of 2 kHz, 6 kV, 48 mJ / pulse, one surface 37 of the holding member 35 and the outer edge of the conductive film 34 were obtained. No discharge occurred in the 2 mm portion between the portion 38 and uniform plasma could not be generated.

Since the plasma generating electrode and the plasma reactor of the present invention can generate stable and uniform plasma with high efficiency, ozone is produced by reacting oxygen contained in an exhaust gas processing apparatus for processing exhaust gas or air. It can be suitably used for an ozonizer to be purified.

It is sectional drawing which shows a cross section perpendicular | vertical to the longitudinal direction of the both ends of a unit electrode in one embodiment of the plasma generation electrode of this invention. It is a perspective view which shows an example of the holding member which comprises one embodiment of the plasma generation electrode of this invention. It is the enlarged view to which the holding member of the plasma generation electrode shown in FIG. 1 was expanded. 4A and 4B are cross-sectional views showing a cross section perpendicular to the longitudinal direction of both end portions of the unit electrode in a plasma generating electrode having a flat one surface of the holding member. It is a perspective view which shows the other example of the holding member which comprises one embodiment of the plasma generation electrode of this invention. It is a perspective view which shows the other example of the holding member which comprises one embodiment of the plasma generation electrode of this invention. It is a perspective view which shows the other example of the holding member which comprises one embodiment of the plasma generation electrode of this invention. It is a perspective view which shows the other example of the holding member which comprises one embodiment of the plasma generation electrode of this invention. It is sectional drawing which shows a cross section perpendicular | vertical to the longitudinal direction of the both ends of the unit electrode in other embodiment of the plasma generation electrode of this invention. 10A is a cross-sectional view of one embodiment of the plasma reactor of the present invention cut along a plane including the gas flow direction, and FIG. 10B is a cross-sectional view taken along line AA in FIG. It is sectional drawing in a line. It is an expanded sectional view which shows a part of cross section perpendicular | vertical to the longitudinal direction of the both ends of a unit electrode in Example 1 of the plasma generating electrode of this invention. It is an expanded sectional view which shows a part of cross section perpendicular | vertical to the longitudinal direction of the both ends of a unit electrode in the comparative example 1 of the plasma generating electrode of this invention. It is an expanded sectional view which shows a part of cross section perpendicular | vertical to the longitudinal direction of the both ends of a unit electrode in the comparative example 2 of the plasma generating electrode of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plasma generating electrode, 2 ... Unit electrode, 2a ... One unit electrode, 2b ... The other unit electrode, 3 ... Ceramic body, 4 ... Conductive film, 5 ... Holding member, 6 ... End part, 7 ... One surface 8 ... concave groove, 9 ... surface, 11 ... plasma reactor, 12 ... case body, 13 ... gas flow path, 14 ... space, 31 ... plasma generating electrode, 32 ... unit electrode, 33 ... ceramic body, 34 ... conductive Membrane, 35 ... holding member, 36 ... end, 37 ... one surface, 38 ... outer edge, 39 ... creeping discharge, A, B ... angle, D ... width of one surface, L ... one surface of holding member Total length including the concave groove.

Claims (12)

Two or more plate-like unit electrodes facing each other, and having a length corresponding to the length in the longitudinal direction of both end portions of the unit electrode and having one surface facing each other, of the both end portions of the unit electrode And a pair of holding members that hold the unit electrodes at a predetermined interval so as to form a space therebetween, and apply a voltage between the unit electrodes. A plasma generating electrode capable of generating plasma by
At least one of the unit electrodes facing each other has a ceramic body serving as a dielectric, and a conductive film disposed inside the ceramic body,
A plasma generating electrode in which a set of the holding members has a concave groove extending over the entire length in the longitudinal direction of the one surface on the one surface facing each other. The plasma generating electrode according to claim 1, wherein the concave groove is composed of two or more planes or one or more curved surfaces, or one or more planes and one or more curved surfaces. 3. The plasma generating electrode according to claim 1, wherein a shape of a cross section perpendicular to the longitudinal direction of the concave groove is a quadrilateral or more polygonal shape, a semicircular shape, a semielliptical shape, or a bullet shape. When the shape of the cross section perpendicular to the longitudinal direction of the concave groove is a quadrilateral or more polygonal shape, the one surface of the holding member, the surface of the concave groove, and the surfaces of the concave groove in the cross section The plasma generating electrode according to any one of claims 1 to 3, wherein the space-side angle is 90 to 270 degrees. The overall length including the concave groove on the one surface of the holding member in a cross section perpendicular to the longitudinal direction of the holding member is 1.3 to 10 times the width of the one surface of the holding member. The plasma generating electrode according to any one of 1 to 4. The angle on the space side constituted by the one surface of the holding member and the surface of the unit electrode in a cross section perpendicular to the longitudinal direction of the holding member is 90 degrees or more. The plasma generating electrode according to any one of the above. The said holding member contains at least 1 type of compound chosen from the group which consists of aluminum oxide, magnesium oxide, silicon oxide, silicon nitride, zirconia, mullite, cordierite, and crystallized glass. Plasma generating electrode. The ceramic body is aluminum oxide, magnesium oxide, silicon oxide, silicon nitride, aluminum nitride, mullite, cordierite, magnesium-calcium-titanium oxide, barium-titanium-zinc oxide, and barium-titanium oxide. The plasma generating electrode according to any one of claims 1 to 7, comprising at least one compound selected from the group consisting of: The conductive film includes at least one metal selected from the group consisting of tungsten, molybdenum, manganese, chromium, titanium, zirconia, nickel, iron, silver, copper, platinum, and palladium. The plasma generating electrode as described. A plasma generating electrode according to any one of claims 1 to 9, and a case body having a gas passage (gas passage) containing a predetermined component therein, wherein the gas flows in the case body. A plasma reactor capable of causing the predetermined component contained in the gas to react with the plasma generated by the plasma generating electrode when introduced into the channel. The plasma reactor according to claim 10, further comprising a pulse power source for applying a voltage to the plasma generating electrode. The plasma reactor according to claim 11, wherein the pulse power source has at least one SI thyristor therein.

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