JP2011171056A - Solution plasma discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solution plasma discharge device that allows a plasma generation region between discharge electrodes to be expanded easily. <P>SOLUTION: The solution plasma discharge device is equipped with a discharge electrode 1a including a linear electrode, and a discharge electrode 1b including a needle electrode. The discharge electrode 1b is inclined toward a longitudinal direction of the discharge electrode 1a. Plasma 13 can be generated by only applying a voltage without increasing the applied voltage between the discharge electrodes 1a, 1b, even if distance between the discharge electrodes 1a, 1b is increased, thereby allowing the plasma generation region 14 to be expanded. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solution plasma discharge apparatus that can easily expand a plasma generation region between discharge electrodes.

  Among technologies using plasma, a technology for generating plasma in a liquid and applying it industrially is being developed. Such plasma in liquid is called “solution plasma” because it is mainly used in solution.

  Solution plasma is plasma generated between discharge electrodes by applying a voltage (high electric field) between two discharge electrodes arranged opposite to each other in a solution. Bubbles are generated around the generated plasma, the bubbles surround the plasma, and the solution surrounds the bubbles. In other words, the solution plasma is characterized by two interfaces: plasma / gas phase and gas phase / liquid phase. As described above, the solution plasma realizes a state in which the “high energy state” due to the plasma is confined in the solution. As a result, various chemical reactions are promoted in the gas phase, the liquid phase or the interface around the plasma. Industrial applications using this chemical reaction include water treatment, sterilization, waste treatment, creation of new materials, development of new synthetic methods for materials, surface modification, ultra-high speed processing, rare metal recovery, super-functional solutions, and aquaculture, etc. And biological cultures containing

  Non-Patent Document 1 describes a synthesis reaction of gold nanoparticles using solution plasma. FIG. 7 is a cross-sectional view showing a solution plasma discharge device (solution plasma generator) 121 described in Non-Patent Document 1. The solution plasma discharge apparatus 121 includes two wire-shaped metal electrodes 101 and 101 that face each other, and the wire-shaped metal electrodes 101 and 101 are fixed to the container 111 by holders 110 and 110, respectively. A chloroauric acid aqueous solution is used as the solution 112 in the container 111. In the solution plasma discharge apparatus 121, when a pulse voltage is applied between the wire-like metal electrodes 101 and 101, a plasma 113 is generated between the wire-like metal electrodes 101 and 101. As a result, gold in the solution 112 (chloroauric acid aqueous solution) is reduced, and gold nanoparticles having a diameter of 10 to 15 nm are synthesized.

  However, in the solution plasma discharge apparatus 121, when the distance between the wire-like metal electrodes 101 and 101 is increased, the applied voltage (plasma discharge start voltage) required for plasma generation increases according to the distance. As the applied voltage increases, the current flowing between the wire-like metal electrodes 101 and 101 also increases, and the surrounding electric and magnetic fields also increase. As a result, there is a problem that the temperature in the solution 112 increases, electromagnetic noise increases, and plasma emission increases.

  Therefore, in order to solve this problem, the inventors of the present application have disclosed a solution plasma discharge device in Patent Document 1. FIG. 8 is a cross-sectional view showing a solution plasma discharge device 221 described in Patent Document 1. As shown in FIG. The solution plasma discharge device 222 has a configuration in which two discharge electrodes 201 a and 201 b are fixed so as to penetrate through a silicon rubber substrate 202. The discharge electrode 201 a is fixed perpendicular to the substrate 202 and inserted into the recess 203. On the other hand, the discharge electrode 201 b is fixed horizontally with respect to the substrate 202 and inserted into the recess 203. The position of the discharge electrode 201b can be moved in the horizontal direction, and the distance from the discharge electrode 201a can be adjusted.

  In the solution plasma discharge apparatus 222, plasma is generated in the region C when a voltage is applied between the discharge electrodes 201a and 201b in a state where the discharge electrode 201b is close to the discharge electrode 201a. Bubbles generated by the plasma fill the recess 203 including the region C. Thereafter, when the discharge electrode 201b is moved away from the discharge electrode 201a, since the region C is already filled with bubbles, the distance between the discharge electrodes 201a and 201b can be increased while maintaining the plasma state.

  Therefore, the solution plasma discharge apparatus 222 can increase the distance between the discharge electrodes 201a and 201b while maintaining the plasma state without increasing the applied voltage. This lowers the voltage per distance between the discharge electrodes 201a and 201b, and reduces the flowing current. Therefore, the heat generated by plasma, electromagnetic wave noise, and the brightness of plasma emission can be reduced.

JP 2010-9993 A (published January 14, 2010)

Osamu Takai, “Nanoparticle Synthesis and Interface Control by Solution Plasma”, Grinding, Hosokawa Institute of Powder Technology, December 28, 2007, No. 51, p. 30-36

  However, the solution plasma discharge device of Patent Document 1 has a problem that the processing for expanding the distance between the discharge electrodes is complicated.

  Specifically, in the solution plasma discharge apparatus 222, in order to increase the distance between the discharge electrodes 201a and 201b and expand the plasma generation region, a multi-stage process is required. That is, first, plasma is generated in the region C in the recess 203 with the discharge electrode 201b close to the tip of the discharge electrode 201a. Next, the bubbles generated by the plasma are filled in the recess 203 including the region C. Subsequently, the discharge electrode 201b is gradually moved away from the discharge electrode 201a. This makes it possible to increase the distance between the discharge electrodes 201a and 201b without increasing the applied voltage.

  As described above, in the solution plasma discharge apparatus 222, complicated processing is required to increase the distance between the discharge electrodes 201a and 201b. In addition, in the solution plasma discharge apparatus 222, the substrate 202 having the recess 203 is also indispensable.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a solution plasma discharge apparatus that can easily expand a plasma generation region between discharge electrodes.

  In order to solve the above problems, a solution plasma discharge apparatus according to the present invention includes a pair of discharge electrodes arranged in a liquid, and applies a voltage between the discharge electrodes to cause discharge, thereby causing a discharge between the discharge electrodes. In the solution plasma discharge apparatus for generating plasma, one of the pair of discharge electrodes is a line electrode, the other is a needle electrode, and the needle electrode is disposed to be inclined with respect to the longitudinal direction of the line electrode. It is characterized by having.

  According to said structure, a pair of discharge electrode which consists of a line electrode and the needle electrode arrange | positioned with respect to a line electrode is provided. Thereby, even if the distance between the discharge electrodes is increased, plasma can be generated without increasing the applied voltage between the discharge electrodes. That is, plasma can be generated between discharge electrodes having a long distance by simply applying a voltage without performing a complicated process as in Patent Document 1. Therefore, the plasma generation region between the discharge electrodes can be easily expanded.

  In the solution plasma discharge apparatus according to the present invention, it is preferable that the distance from the tip of the needle electrode to the intersection of the extension line of the needle electrode and the line electrode is constant during the generation of the plasma.

  According to said structure, it is not necessary to change the distance between discharge electrodes during plasma generation. Therefore, the plasma generation region between the discharge electrodes can be expanded more easily.

  In the solution plasma discharge apparatus according to the present invention, it is preferable that an intermediate portion of the line electrode is disposed on an extension line of the needle electrode.

  According to said structure, a needle electrode is arrange | positioned facing the intermediate part of a line electrode. Thereby, the extension line of the needle electrode becomes the axis of symmetry of the line electrode. For this reason, line electrodes are symmetrically arranged on both sides of the extension line. Therefore, the plasma generation region can be further expanded.

  In the solution plasma discharge apparatus according to the present invention, it is preferable that the needle electrode is disposed perpendicular to the longitudinal direction of the line electrode.

  According to the above configuration, the angle formed by the extension line of the needle electrode and the longitudinal direction of the line electrode is 90 °. Thereby, the direction perpendicular to the extension line of the needle electrode becomes the longitudinal direction of the line electrode. That is, the distance in the longitudinal direction from the needle electrode to the line electrode is constant. Accordingly, it is possible to form a plasma generation region that spreads uniformly between the discharge electrodes.

  In the solution plasma discharge apparatus according to the present invention, the line electrode may be stretchable in the longitudinal direction.

  According to the above configuration, since the length of the line electrode varies, the length of the portion where the line electrode is exposed in the liquid (exposure length) also varies. As a result, the exposed length of the line electrode can be varied while keeping the shortest distance between the discharge electrodes constant. Therefore, the length of the line electrode can be finely adjusted so that the exposure length suitable for the state of the generated plasma is obtained.

  In the solution plasma discharge apparatus according to the present invention, as described above, one of the pair of discharge electrodes is a line electrode, the other is a needle electrode, and the needle electrode is in the longitudinal direction of the line electrode. It is the structure arrange | positioned in inclination. For this reason, there is an effect that the plasma generation region between the discharge electrodes can be easily expanded without performing complicated processing.

It is a perspective view of the vicinity of the plasma generation region in the solution plasma discharge apparatus according to the present invention. It is sectional drawing which shows the solution plasma discharge apparatus which concerns on this invention. It is a perspective view which shows another arrangement | positioning state of the discharge electrode in the solution plasma discharge apparatus which concerns on this invention. It is a figure which shows a plasma generation | occurrence | production area | region in the solution plasma discharge apparatus which concerns on this invention. (A) is a top view which shows a pair of discharge electrode arrange | positioned at I type, (b) is a figure which shows the plasma generation area | region which generate | occur | produced between the discharge electrodes of (a). (A) is a top view which shows a pair of discharge electrode arrange | positioned at V shape, (b) is a figure which shows the plasma generation | occurrence | production area | region which generate | occur | produced between the discharge electrodes of (a). It is sectional drawing of the solution plasma discharge device described in the nonpatent literature 1. It is sectional drawing of the solution plasma discharge apparatus described in patent document 1. FIG.

  An embodiment of the present invention will be described below with reference to the drawings.

  The solution plasma discharge device of the present invention expands the plasma generation region by a pair of discharge electrodes composed of a line electrode and a needle electrode.

FIG. 2 is a cross-sectional view showing a solution plasma discharge apparatus 21 according to an embodiment of the present invention. The solution plasma discharge device 21 is placed in the solution (liquid) 12 in the container 11.
A pair of discharge electrodes 1a and 1b is provided.

  The discharge electrode 1a is a line electrode provided horizontally (parallel to the liquid surface of the solution 12).

  On the other hand, the discharge electrode 1b is provided close to the discharge electrode 1a, and is inclined with respect to the longitudinal direction of the discharge electrode 1a. Further, the discharge electrode 1a is disposed on the extended line of the discharge electrode 1b. However, the tip of the discharge electrode 1a is not disposed on the extension line. In the present embodiment, the discharge electrode 1b is disposed perpendicular to the discharge electrode 1a, and an intermediate portion (center portion) of the discharge electrode 1a is disposed on an extension line of the discharge electrode 1b. Further, during plasma generation, the distance from the tip of the discharge electrode 1b to the intersection of the extension line of the discharge electrode 1b and the discharge electrode 1a is constant.

  The discharge electrodes 1a and 1b are covered with ceramic tubes 10 and 10 so as to have exposed portions in the solution 12. The length exposed in the solution 12 of the discharge electrode 1a (exposure length) is not particularly limited, but is 3 cm in the present embodiment. On the other hand, the length exposed in the solution 12 of the discharge electrode 1b (exposure length) is not particularly limited, but is 2 mm in the present embodiment. Further, the length of the discharge electrode 1a varies.

  A voltage is supplied to the discharge electrodes 1a and 1b from a power source (not shown). As a result, plasma is generated between the discharge electrodes 1a and 1b. The power supply conditions are not particularly limited as long as plasma is generated. That is, the voltage value, pulse width, pulse frequency, pulse waveform, etc. are not particularly limited.

  Further, the interelectrode distance, size, material, and the like of the discharge electrodes 1a and 1b are not particularly limited. In the present embodiment, a rod-shaped electrode having a diameter of 1 mm is used as the discharge electrode 1a, and a needle electrode having a diameter of 1 mm is used as the discharge electrode 1b. The distance between the discharge electrodes 1a and 1b is 5 mm, which is longer than that of a normal solution plasma discharge apparatus. The discharge electrodes 1a and 1b can be made of tungsten, copper, or other conductive material.

  The solution 12 may include an electrolyte for adjusting the conductivity of the solution 12 in addition to an arbitrary solute to be subjected to a chemical reaction. Further, the solution 12 does not need to contain a solute with the solvent itself as a target of reaction. The combination of the solute and the solvent constituting the solution 12, the concentration, conductivity, pH, etc. of the solution 12 may be set according to the purpose and are not particularly limited.

  Next, generation of plasma in the solution plasma discharge apparatus 21 will be described with reference to FIG. FIG. 1 is a perspective view showing the vicinity of the plasma generation region 14 of the solution plasma discharge device 21.

  When a voltage (for example, about 1100 V) is applied between the discharge electrodes 1a and 1b, the solution plasma discharge device 21 is discharged and plasma is generated between the discharge electrodes 1a and 1b. Further, during this discharge, the solution 12 is heated by the current flowing between the discharge electrodes 1a and 1b. Thereby, bubbles are generated in the solution 12, particularly around the plasma 13. Bubbles generated during voltage application surround the plasma 13 and the plasma state is stabilized and maintained inside the bubbles. The plasma generation region 14 includes a plasma 13 and a gas phase containing the plasma 13. Thus, the gas phase surrounds the plasma 13 (plasma phase), and the liquid phase surrounds the gas phase. Such a plasma state promotes various chemical reactions of molecules in the gas and in the solution.

  Here, if the plasma generation region 14 is wide, such various chemical reactions proceed efficiently. The plasma generation region 14 can be expanded by increasing the distance between the discharge electrodes 1a and 1b. However, when the distance between the discharge electrodes 1a and 1b is increased, the applied voltage required for plasma generation is usually increased according to the distance. For this reason, in Patent Document 1, a member (substrate 202) only for expanding a plasma generation region under a low voltage is an indispensable constituent requirement, and multistage processing is also an indispensable requirement.

  However, in the solution plasma discharge device 21 of this embodiment, the discharge electrode 1a is a line electrode, the discharge electrode 1b is a needle electrode, and the discharge electrode 1b is inclined with respect to the longitudinal direction of the discharge electrode 1a. Thereby, even if the distance between the discharge electrodes 1a and 1b is increased, the plasma 13 can be generated without increasing the applied voltage between the discharge electrodes 1a and 1b. That is, the plasma 13 can be generated between the discharge electrodes 1a and 1b having a long distance only by applying a voltage without performing a complicated process as in Patent Document 1. Therefore, the plasma generation region 14 between the discharge electrodes 1a and 1b can be easily expanded. Therefore, various chemical reactions can proceed efficiently. For example, the synthesis efficiency of nanoparticles can be increased.

  In Patent Document 1, there is no description or suggestion that one of the discharge electrodes 201a and 201b is a line electrode and the other is a needle electrode. That is, the effect that the plasma generation region 14 can be expanded in the solution plasma discharge device 21 is an effect unique to the present invention, which can be obtained only by arranging a specific discharge electrode in a specific arrangement.

  Further, the solution plasma discharge apparatus 21 does not require the substrate 202 having the recess 203 as in Patent Document 1 in order to increase the distance between the discharge electrodes 1a and 1b. For this reason, the number of parts can be reduced as compared with the solution plasma discharge device of Patent Document 1. Therefore, the configuration of the solution plasma discharge device 21 can be simplified.

  In the solution plasma discharge device 21, the distance from the tip of the discharge electrode 1b to the intersection of the extension line of the discharge electrode 1b and the discharge electrode 1a is constant during plasma generation (voltage is applied to the discharge electrodes 1a and 1b). Preferably there is. That is, in this case, it is not necessary to change the distance between the discharge electrodes 1a and 1b during plasma generation. Therefore, the plasma generation region 14 between the discharge electrodes 1a and 1b can be more easily expanded.

  Further, in the solution plasma discharge device 21, the discharge electrode 1a is extendable in the longitudinal direction, and the length of the discharge electrode 1a varies. However, the length of the discharge electrode 1a is not less than the length when the tip of the discharge electrode 1a is disposed on the extended line of the discharge electrode 1b. In other words, the length of the discharge electrode 1a varies within a range in which the discharge electrode 1b is disposed to be inclined with respect to the longitudinal direction of the discharge electrode 1a. In this case, the length of the portion where the discharge electrode 1a is exposed in the solution 12 (exposure length) also varies. Thereby, the exposure length of the discharge electrode 1a can be varied while keeping the shortest distance between the discharge electrodes 1a and 1b constant. Therefore, the length of the discharge electrode 1a can be finely adjusted so that the exposure length suitable for the state of the generated plasma 13 is obtained. Of course, the length of the discharge electrode 1a may not be changed (expanded).

  Further, in the solution plasma discharge device 21, the position of the discharge electrode 1b with respect to the discharge electrode 1a is not particularly limited as long as the discharge electrode 1b is inclined with respect to the longitudinal direction of the discharge electrode 1a. However, it is preferable that the intermediate part of the discharge electrode 1a is disposed on the extended line of the discharge electrode 1b. That is, like the solution plasma discharge device 21, it is preferable that the discharge electrode 1b is disposed so as to face the intermediate portion of the discharge electrode 1a. Thereby, the extension line of the discharge electrode 1b becomes an axis of symmetry of the discharge electrode 1a. That is, the discharge electrodes 1a are arranged symmetrically on both sides of the extension line. That is, the intersection of the extension line of the discharge electrode 1b and the discharge electrode 1a is substantially the middle point of the discharge electrode 1a. Thereby, the plasma generation region 14 extending in the longitudinal direction of the discharge electrode 1a is formed. Therefore, the plasma generation region can be further expanded.

  Moreover, in the solution plasma discharge apparatus 21, the discharge electrode 1b is arrange | positioned perpendicularly | vertically with respect to the longitudinal direction of the discharge electrode 1a. That is, the angle formed by the extension line of the discharge electrode 1b and the longitudinal direction of the discharge electrode 1a is 90 °. Thereby, the direction perpendicular to the extended line of the discharge electrode 1b becomes the longitudinal direction of the discharge electrode 1a. That is, the distance in the longitudinal direction from the discharge electrode 1b to the discharge electrode 1a is constant. Accordingly, it is possible to form the plasma generation region 14 that spreads evenly between the discharge electrodes 1a and 1b.

  In addition, the angle of the discharge electrode 1b with respect to the longitudinal direction of the discharge electrode 1a is not specifically limited. That is, this angle may be vertical, obtuse, or acute as long as the discharge electrode 1b is inclined with respect to the longitudinal direction of the discharge electrode 1a. FIG. 3 is a perspective view showing another arrangement state of the discharge electrodes 1a and 1b. In FIG. 3, the discharge electrode 1b is disposed at an acute angle with respect to the longitudinal direction of the discharge electrode 1a. Even in such an arrangement state, the plasma generation region (not shown) can be similarly expanded.

  Using the discharge electrode 1a (line electrode) and the discharge electrode 1b (needle electrode) arranged in a T shape as shown in FIG. 2, the distance between the discharge electrodes 1a and 1b (the extension line of the discharge electrode 1b from the tip of the discharge electrode 1b) The distance between the electrode and the discharge electrode 1a) was 5 mm, a voltage of 2000 V was applied between the discharge electrodes 1a and 1b for about 5 seconds, and the plasma generation region formed was observed. FIG. 4 is a diagram showing the observed plasma generation region.

  On the other hand, for comparison, the plasma generation region was similarly observed for two types of solution plasma discharge devices that differ only in the arrangement state of the discharge electrodes. In other words, as shown in FIG. 5A, one of the discharge electrodes 1c and 1c used was a needle electrode arranged in an I-shape opposed to each other. The other was a needle electrode as shown in FIG. 6A, in which the discharge electrodes 1d and 1d are arranged in a V shape when the extension lines of the discharge electrodes 1d and 1d are connected. In FIGS. 5 (a) and 6 (a), the distance between the discharge electrodes indicated by the double arrow is 5 mm.

  FIG. 5B is a view showing a plasma generation region generated between the discharge electrodes in FIG. FIG. 6B shows a plasma generation region generated between the discharge electrodes in FIG.

  As a result of examining the relationship between the arrangement state of the discharge electrode and the plasma generation region, as shown in FIG. 4, when the discharge electrodes 1a and 1b are arranged in a T-shape, the plasma generation region is spread evenly in a spherical shape. (The white part in the figure) was formed, and it was confirmed that the plasma generation region was expanded most.

  On the other hand, when the discharge electrodes are arranged in an I shape or a V shape as shown in FIGS. 5B and 6B, a linear plasma generation region is formed in a region connecting the tips of the discharge electrodes. However, no uniform spread was confirmed as in the plasma generation region of FIG.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range shown to the claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention can be used for material synthesis, liquid processing, processing and the like using solution plasma. In addition, diagnosis (observation) of the solution plasma state can be facilitated and applied to control of the solution plasma state.

1a Discharge electrode (line electrode)
1b Discharge electrode (needle electrode)
12 Solution (liquid)
13 Plasma 14 Plasma generation region 21 Solution plasma discharge device

Claims (5)

In a solution plasma discharge apparatus comprising a pair of discharge electrodes arranged in a liquid and generating a plasma between the discharge electrodes by applying a voltage between the discharge electrodes to cause discharge.
One of the pair of discharge electrodes is a line electrode, the other is a needle electrode,
The solution plasma discharge apparatus according to claim 1, wherein the needle electrode is disposed to be inclined with respect to the longitudinal direction of the line electrode.   2. The solution plasma discharge device according to claim 1, wherein a distance from the tip of the needle electrode to the intersection of the extension line of the needle electrode and the line electrode is constant during the generation of the plasma.   The solution plasma discharge device according to claim 1, wherein an intermediate portion of the line electrode is disposed on an extension line of the needle electrode.   The solution plasma discharge device according to any one of claims 1 to 3, wherein the needle electrode is disposed perpendicular to a longitudinal direction of the line electrode.   The solution plasma discharge device according to claim 1, wherein the line electrode is extendable in the longitudinal direction.