JP4978566B2 - Atmospheric pressure plasma generation method and apparatus - Google Patents

Description

  The present invention relates to an atmospheric pressure plasma generation method and apparatus, and more particularly to an atmospheric pressure plasma generation method and apparatus that reduce noise emitted from atmospheric pressure plasma.

  Conventionally, plasma is generated by supplying a plasma generating gas to a predetermined reaction space under atmospheric pressure or a pressure near it, and applying a high-frequency voltage to an antenna or electrode disposed in the vicinity of the reaction space. Such an atmospheric pressure plasma generator is known (see, for example, Patent Document 1).

  A configuration example of this type of atmospheric pressure plasma generator will be described with reference to FIGS. As shown in FIG. 11, a gas 13 is supplied from one end 11 a of a reaction tube 11 that forms a predetermined reaction space, and a matching antenna 7 is connected from a high-frequency generator 3 to a coiled antenna 6 disposed around the reaction tube 11. By applying a high-frequency voltage via the, a plasma 14 is generated in the reaction space in the reaction tube 11 and the plasma 14 is blown out from the other end 11 b of the reaction tube 11. As shown in FIG. 12, the matching circuit 7 includes an inductance element 8 (L1) disposed between one end 6a of the antenna 6 and the high-voltage terminal side of the high-frequency generator 3, and a ground terminal side of the high-frequency generator 3 A capacitor element 9 (C1) disposed between the other end 6b of the antenna 6 and a capacitor element 10 (C2) disposed in parallel with the antenna 6 between the high-voltage terminal and the ground terminal of the high-frequency generator 3 It consists of and. Further, as shown in FIG. 13, the plasma head 2 that generates plasma 14 and irradiates the surface to be processed includes a reaction tube 11 and an antenna 6, a matching circuit 7, and both ends of the reaction tube 11. The surroundings are covered with a shielding cover 15 made of a metal material except for the portion, and the connector 5 of the coaxial cable 4 to which a high-frequency voltage is supplied from the high-frequency generator 3 is provided so as to protrude from the shielding cover 15 and discharged to the outside. The thing of the structure which aimed at reduction of the high frequency noise which is considered is considered.

Further, as an atmospheric pressure plasma generator for preventing the emission of high frequency noise, a device having a structure as shown in FIG. 15 is known (see, for example, Patent Document 2). In FIG. 15, a pair of electrodes 62 a and 62 b are arranged on the outer periphery of a rectangular tube-shaped reaction vessel 61 that supplies gas from one end with an axial center interval, and a high-frequency power supply 63 applies an antiphase to the matching circuit 64. A high-frequency voltage having phases opposite to each other is applied to the pair of electrodes 62a and 62b via the means 65. The anti-phase applying means 65 includes a primary winding 66 connected to the matching circuit 64 and a secondary winding 67 whose ground point 68 is grounded. One end 67a of the secondary winding 67 is connected to one electrode 62a. The other end 67b is connected to the other electrode 62b. Accordingly, in the conventional configuration, as shown in FIG. 16A, the high-voltage terminal and the ground terminal of the high-frequency power source are connected to both the electrodes 62a and 62b, the other electrode 62b is at the ground potential, and the one electrode 62a has a predetermined value. Since a high frequency voltage of voltage V is applied, high frequency noise is emitted to the outside. In this configuration, as shown in FIG. 16B, a pair of high frequency power sources 63a having ground terminals connected to each other, The high-voltage terminal 63b is connected to the electrodes 62a and 62b, respectively, and a high-frequency voltage having a voltage of V / 2 opposite to each other is applied to the electrodes 62a and 62b. Thus, the high frequency noises cancel each other, and the high frequency noises can be prevented from being emitted to the outside.
Japanese Patent No. 3616088 JP 2001-334147 A

  By the way, in the atmospheric pressure plasma generator as shown in FIGS. 11 and 12, the reaction tube from which the plasma 14 blows out even in the case where the plasma head 2 covered with the shielding cover 15 as shown in FIG. 13 is provided. It has been found that there is a problem that high-frequency noise emitted from the other end 11b of 11 cannot be eliminated.

  Further, as shown in FIG. 13, when the antenna 21a is disposed at a predetermined distance from the other end 11b of the reaction tube 11 and the noise emitted by the noise measuring means 21 is measured, as shown in FIG. Since the matching circuit 7 is adjusted and set so that the reflected wave is close to zero when the plasma 14 is turned on, a reflected wave of 6 to 7 W is generated when the plasma 14 is turned off. Is less than 65 dBμV / m when the plasma is extinguished, but a high noise of 70 to 75 dBμV / m is measured when the plasma is turned on, and noise countermeasures are required.

  On the other hand, the noise countermeasure disclosed in Patent Document 2 is an antenna or electrode configuration that cannot apply a reverse-phase voltage centered on the ground potential, for example, a coil shape or a wave disposed near the reaction tube 11. There is a problem that it is difficult to apply to a configuration in which plasma is generated by applying a high-frequency voltage to both ends of the antenna 6 having a shape. Even if a high-frequency voltage having an opposite phase is applied, it is found that there is a problem that it is difficult to effectively reduce noise because a large phase shift easily occurs in the high-frequency region. did. Furthermore, it was found that noise was emitted from the plasma 14 to be blown out as the experiment was repeated, and it was found that measures to reduce such noise were also necessary. In this way, the generation of high-frequency noise in the atmospheric pressure plasma generator is diverse, and there are various regulations regarding high-frequency noise in each country, so it is possible to effectively reduce high-frequency noise of any level. Proposals for new solutions are required.

  The present invention solves the above-described conventional problems, and provides an atmospheric pressure plasma generation method and apparatus that can reliably prevent high-frequency noises that are generated variously in the process of generating atmospheric pressure plasma from being released to the surroundings. For the purpose.

  The atmospheric pressure plasma generation method of the present invention includes a plasma generation step of generating a plasma by supplying a gas to a reaction space near the atmospheric pressure and applying a high frequency voltage, and a noise canceling antenna disposed in the vicinity of the plasma generation position. A noise canceling radio wave generating step of generating a noise canceling radio wave by supplying a high frequency voltage having a predetermined phase difference and a predetermined amplitude at the same frequency as the high frequency voltage, the predetermined phase difference and the predetermined amplitude being The noise measured in the vicinity of the plasma generation position is set in advance so as to be minimal or in the vicinity thereof. In addition, the atmospheric pressure vicinity means the pressure of the vicinity including atmospheric pressure, and is specifically the pressure range of about 500 mmHg-1500 mmHg.

  According to this configuration, noise is measured in the vicinity of the plasma generation position, and a high-frequency voltage having a predetermined phase difference and a predetermined amplitude is applied to the noise canceling antenna disposed in the vicinity of the plasma generation position so that the noise approaches the minimum. By generating a noise canceling radio wave, even if a variety of noises are generated, it can be reliably erased with a noise canceling radio wave adjusted and set to correspond to it, generating atmospheric pressure plasma Thus, it is possible to reliably prevent high-frequency noise generated in various ways from being released to the surroundings.

  Further, when the predetermined phase difference and the predetermined amplitude are changed between when the plasma is turned on and when the plasma is turned on, even if the generation state of high frequency noise generated when the plasma is turned on and turned off differs, Alternatively, since the phase and amplitude of the high-frequency voltage supplied to the electrodes are changed, it is possible to reliably prevent high-frequency noise from being emitted at any time.

  In addition, a plasma generation step of supplying a gas to a reaction space near the atmospheric pressure and generating a plasma by applying a high frequency voltage, and a noise canceling antenna disposed near the plasma generation position at the same frequency as the high frequency voltage. A noise canceling radio wave generating step of generating a noise canceling radio wave by supplying a high frequency voltage having a predetermined phase difference and a predetermined amplitude, and measuring the predetermined phase difference and the predetermined amplitude in the vicinity of the plasma generation position The noise may be controlled to be minimal or in the vicinity thereof, and the feedback control may be continuously performed while generating plasma.

  In addition, when the high-frequency voltage is in the RF frequency band, VHF frequency band, or microwave frequency band, inductively coupled plasma can be efficiently generated particularly under atmospheric pressure, and in that case, the phase Since the deviation easily occurs, the above effect is remarkably exhibited, which is particularly preferable.

  An atmospheric pressure plasma generator of the present invention includes a plasma head having a reaction space near atmospheric pressure and an antenna or an electrode disposed in the vicinity of the reaction space, a gas supply unit for supplying gas to the reaction space, A high-frequency generator that applies a high-frequency voltage to the antenna or electrode, a matching circuit that is disposed between the high-frequency generator and the antenna or electrode, and that adjusts the reflected power from the antenna or electrode; A noise canceling antenna disposed in the vicinity of the outside, a noise canceling voltage applying means for applying to the noise canceling antenna a high frequency voltage having the same frequency as the high frequency voltage and having a predetermined phase difference and a predetermined amplitude, and a plasma generation position The predetermined phase difference and predetermined amplitude at which the noise measured in the vicinity is minimum or in the vicinity thereof are preset and based on the set value It is obtained and a control unit for controlling the high-frequency voltage outputted from the noise erasing voltage applying means.

  According to this configuration, the noise is measured in the vicinity of the plasma generation position, and the noise erasing voltage applying means is controlled by the control unit, and the high-frequency voltage having a predetermined phase difference and a predetermined amplitude so as to bring the noise close to the minimum. To the noise canceling antenna placed near the plasma generation position, noise canceling radio waves can be generated from the noise canceling antenna so that the noise can be canceled. It can be surely erased by the noise elimination radio wave that has been set and adjusted, and it is possible to reliably prevent the high-frequency noise that is generated variously in the process of generating atmospheric pressure plasma from being released to the surroundings.

  In addition, when the control unit is configured to change the predetermined phase difference and the predetermined amplitude between when the plasma is turned on and when the plasma is turned off, the generation state of the high-frequency noise generated when the plasma is turned on and off is different. However, since the phase and amplitude of the high-frequency voltage supplied to the antenna are changed correspondingly, it is possible to reliably prevent high-frequency noise from being emitted at any time.

  In addition, a plasma head having a reaction space near atmospheric pressure and an antenna or electrode disposed in the vicinity of the reaction space, a gas supply unit that supplies gas to the reaction space, and a high-frequency voltage to the antenna or electrode A high frequency generator to be applied, a matching circuit that is disposed between the high frequency generator and the antenna or electrode, and that adjusts reflected power from the antenna or electrode, and noise that is disposed in or near the plasma head An erasing antenna, a noise erasing voltage applying means for applying a high frequency voltage having the same frequency as the high frequency voltage and having a predetermined phase difference and a predetermined amplitude to the noise erasing antenna, and noise measured in the vicinity of the plasma generation position is minimized The high frequency voltage output from the noise erasing voltage applying means is controlled so that the predetermined phase difference and predetermined amplitude in the vicinity thereof are obtained. A configuration in which a control unit which may be continuous feedback control while generating a plasma.

The plasma head includes the reaction space and an antenna or an electrode, and generates a primary plasma. A mixed gas of an inert gas and a reactive gas is introduced into a space communicating with the reaction space. A secondary plasma generator that generates a secondary plasma by colliding the primary plasma with a second gas consisting of the secondary gas, and develops the secondary plasma with a small primary plasma generated with a small electric power. Therefore, it is possible to efficiently generate high-pressure atmospheric pressure plasma, and according to the above configuration, it is possible to reliably prevent noise generated from such a plasma head.

  The plasma head is covered with a shielding cover made of a metal material except for a portion for injecting the primary plasma or the secondary plasma and a portion for supplying the gas and the second gas. It is suitable to incorporate. By doing so, the antenna or electrode of the plasma generation unit and the matching circuit are shielded by the metal material, so that it is possible to reliably prevent noise generated inside from being released to the outside, and Since only the gas supply portion emits noise, it is possible to more reliably prevent noise from being emitted to the outside of the plasma head.

  If the noise canceling antenna is arranged near the antenna or electrode and built in the plasma head, the noise canceling action can be achieved in the plasma head, and the protrusion that may interfere with surrounding members during the operation of the plasma head. It can be set as a compact structure without an object.

  According to the atmospheric pressure plasma generation method and apparatus of the present invention, noise is measured in the vicinity of the plasma generation position, and a predetermined phase difference is applied to the noise canceling antenna disposed in the vicinity of the plasma generation position so that the noise approaches the minimum. By generating a noise canceling radio wave by supplying a high frequency voltage having a predetermined amplitude, it is possible to reliably erase even a variety of generated noise with a noise canceling radio wave set and adjusted to correspond to it. Therefore, it is possible to reliably prevent various noises generated in the process of generating atmospheric pressure plasma from being emitted to the surroundings.

  Hereinafter, each embodiment of the atmospheric pressure plasma generator according to the present invention will be described with reference to FIGS.

(First embodiment)
First, a first embodiment of the atmospheric pressure plasma generator of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the atmospheric pressure plasma generator 1 of the present embodiment has an RF frequency band, a VHF frequency band, or a microwave frequency band using a plasma head 2 and a commercial AC power source (not shown) as power sources. A high-frequency voltage generator 3 that generates a high-frequency voltage, and is configured to supply the high-frequency voltage from the high-frequency voltage generator 3 through the coaxial cable 4 and the connector 5 provided in the plasma head 2. The basic configuration of the plasma head 2 is the same as the conventional configuration described with reference to FIGS. 11 and 12, and as shown in FIG. 11, a reaction tube 11 made of a dielectric material and forming a reaction space therein. And a coiled or corrugated antenna 6 disposed in the vicinity of the reaction tube 11, via a matching circuit 7 that reduces the reflected wave from the antenna 6 to the antenna 6 from the high frequency generator 3. A high frequency voltage is applied. The matching circuit 7 is built in the plasma head 2, and as shown in FIG. 12, an inductance element 8 (L1) disposed between the high voltage terminal 5a of the connector 5 and one end 6a of the antenna 6, and the ground of the connector 5 The capacitor element 9 (C1) on the turn side disposed between the terminal 5b and the other end 6b of the antenna 6 and the high voltage terminal 5a of the connector 5 and the ground terminal 5b disposed in parallel with the antenna 6 It is comprised with the load side capacitor | condenser element 10 (C2).

  In addition, the gas supply unit 12 is configured to supply a gas 13 for plasma generation made of an inert gas or a mixed gas of an inert gas and a reactive gas from one end 11a of the reaction tube 11 to the internal reaction space. . Thus, plasma 14 is generated in the reaction space in the reaction tube 11 by supplying a gas 13 to the reaction space in the reaction tube 11 and applying a high-frequency voltage from the high-frequency generator 3 to the antenna 6 via the matching circuit 7. Then, the plasma 14 is blown out from the other end 11 b of the reaction tube 11.

  The plasma head 2 has only one end 11a and the other end 11b of the reaction tube 11 protruding, and its outer surface is covered with a metal shielding cover 15, and high frequency noise generated by the antenna 6 and the matching circuit 7 is externally generated. Is prevented from being released. Further, a part of the connector 5, that is, a connection terminal 5 c for connecting the connector terminal 5 d on the coaxial cable 4 side protrudes from the shielding cover 15.

  A noise canceling antenna 16 is disposed in the vicinity of the reaction tube 11 serving as a plasma generating unit inside or outside the plasma head 2. A high-frequency voltage having the same frequency as the high-frequency voltage supplied to the antenna 6 from the high-frequency generator 3 via the phase circuit 17 and the amplifier 18 and having a predetermined phase difference and a predetermined amplitude is applied to the noise canceling antenna 16. It is comprised so that it may apply. These phase circuit 17 and amplifier 18 constitute a noise elimination voltage applying means 19 and a control unit 20 is configured to adjust and set the phase difference and amplitude. Note that a high frequency voltage is applied to one end of the noise erasing antenna 16 and the other end is grounded (GND).

  Reference numeral 21 denotes noise measuring means for measuring noise emitted from the plasma head 2, and the antenna 21a is arranged at a predetermined distance L (3 m) from the other end 11b of the reaction tube 11 from which the plasma 14 blows out. Noise measurement is performed by the 3m method. The control unit 20 is set in advance so that the noise measured by the noise measuring unit 21 is minimized or in the vicinity thereof, and the phase circuit 17 and the amplifier 18 are adjusted by the control unit 20.

  In the present embodiment, a CR circuit composed of a known capacitive element and a resistive element is applied to the phase circuit 17, and a known amplifier whose output is changed by changing the gate voltage is applied to the amplifier 18. Furthermore, as described with reference to FIG. 14, since the level of noise emitted differs between when the plasma 14 is turned on and when the plasma 14 is turned off, the phase circuit 17 and the amplifier 18 are different in each case. Adjusted.

  The setting of the control unit 20 for adjusting the phase circuit 17 and the amplifier 18 is performed in advance before shipment of the atmospheric pressure plasma generator 1 or before actual operation. Further, adjustment is set by stopping operation during actual operation as required. The actual setting operation involves applying a high-frequency voltage from the high-frequency generator 3 to the antenna 6 via the matching circuit 7 and supplying a gas 13 to the reaction tube 11 to turn on the plasma 14 having a predetermined power. 3 and the gas supply unit 12 are adjusted and the adjustment value is set in the control unit 20, and then the adjustment value in a state where the plasma 14 is turned off is set in the control unit 20. Next, with the plasma 14 turned off, the noise is measured by the noise measuring means 21, and the adjustment value is set by adjusting the CR circuit of the phase circuit 17 so that the measured value is minimized or in the vicinity thereof. That is, as shown in FIG. 2A, with the amplification factor of the amplifier 18 kept constant, between the high frequency generator 3 (point A in FIG. 1) and the phase circuit 17 exit (point D in FIG. 1). The noise measurement level is measured while changing the phase angle by adjusting the phase circuit 17, the phase circuit 17 is adjusted to the phase angle a at which the noise measurement level is minimum or close thereto, and the adjustment value is sent to the control unit 20. Next, as shown in FIG. 2 (b), the noise measurement level is measured while changing the amplification degree of the amplifier 18, and the amplifier 18 is adjusted to the amplification degree b at which the noise measurement level is minimized or in the vicinity thereof. The adjustment value is set in the control unit 20. Next, with the plasma 14 turned on, the phase circuit 17 is similarly adjusted, the adjustment value is set in the control unit 20, the amplifier 18 is adjusted, and the adjustment value is set in the control unit 20. Thus, during actual operation of the atmospheric pressure plasma generator 1, the control circuit 20 automatically adjusts the phase circuit 17 and the amplifier 18 to the respective set values when the plasma 14 is turned off and when the plasma 14 is turned on. The release level of is reliably suppressed to a minimum.

  As a configuration in which the phase is changed between when the plasma 14 is turned on and when the plasma 14 is turned off, the phase circuit 17 and the CR circuit, as shown in FIG. It is composed of a plurality of divided energization paths 22a having an energization path length d between a point D of the outlet terminal and a parallel energization path 22b and a switch 23 (SW) for opening / closing the same in any divided energization path 22a. A configuration may be adopted in which the current path 22 is provided and the phase is changed by changing the length of the current path at a high frequency by opening and closing the switch 23 (SW). That is, when the switch 23 (SW) is opened as shown in FIG. 3A, the current path length between the H point and the D point is 3d with respect to the high frequency, whereas FIG. ), When the switch 23 is closed, the energization path length between the point H and the point D becomes as short as 2d with respect to the high frequency. Therefore, at a high frequency, the phase can be delayed with respect to the case of FIG. 3B by opening the switch 23 (SW) as shown in FIG. 3A, and can be easily switched by the switch 23 (SW).

  By adjusting and setting the phase circuit 17 and the amplifier 18 as described above, the phase at the point A of the output terminal of the high frequency generator 3 and the phase at the point B of the other end of the antenna 6 (see FIG. 12). The phase at the point C of the other end 11b of the discharge tube 11 that is the blow-out part of the plasma 14, the phase at the point D at the outlet of the adjusted phase circuit 17, and the phase at the point E at the outlet of the amplifier 18 4 and the phase at point F of the noise canceling antenna 16 are as shown in FIG. Actually, a slight phase shift occurs between the point B and the point C, and there is also a phase shift between the point E and the point F. However, the phase is adjusted and set according to the noise level measured by the noise measuring unit 21, and finally In addition, since the phase and amplitude at the point C and the phase and amplitude at the point F cancel each other out of phase with each other, it is possible to reliably prevent noise from being emitted to the periphery.

(Second Embodiment)
Next, a second embodiment of the atmospheric pressure plasma generator of the present invention will be described with reference to FIGS. In the following description of the embodiments, the same components as those of the preceding embodiments are denoted by the same reference numerals, and the description thereof will be omitted. Only differences will be mainly described.

  In the first embodiment, the example is shown in which the operator reads the measurement result by the noise measuring means 21 and operates the control unit 20 according to the measurement result to adjust the phase circuit 17 and the amplifier 18. In the present embodiment, as shown in FIG. 5, the measurement result by the noise measuring means 21 is input to the control unit 20, and the control unit 20 is set so that the measured noise becomes the minimum or the vicinity thereof. The phase circuit 17 and the amplifier 18 are adjusted based on the setting.

  Further, in the present embodiment, as shown in FIG. 6, the phase circuit 17 includes an energization path 22 including a large number (1 to N) of divided energization paths 22a and parallel energization paths 22b parallel to the respective divided energization paths 22a. The switch 23 (SW1, SW2,... SW (N-1), SWN) for opening / closing each parallel energization path 22b is provided, and the control unit 20 controls the opening / closing of each switch 23. Has been. The gate voltage of the amplifier constituting the amplifier 18 is controlled by an amplification factor control means including a D / A converter of the control unit 20. The phase circuit 17 may be provided with a CR circuit, but may not be provided.

  According to the present embodiment, the control unit 20 is automatically set based on the measurement result by the noise measurement unit 21 so that the measured noise is minimum or in the vicinity thereof. The amplifier 18 is automatically adjusted.

(Third embodiment)
Next, a third embodiment of the atmospheric pressure plasma generator of the present invention will be described with reference to FIGS.

  In the present embodiment, as shown in FIG. 7, the high frequency generator 3, the phase circuit 17, the amplifier 18, and the controller 20 are built in the control device 24 to form a unit, and the control device 24 and the plasma head 2 are connected to the coaxial cable 3. The noise elimination antenna 16 is built in the plasma head 2 and a connector 25 connected to the noise elimination antenna 16 is provided on the shielding cover 15 so that the amplifier 18 and the connector 25 of the control device 24 are connected. A coaxial cable 26 is used for connection. An opening 27 is formed in the shielding cover 15 for guiding the electromagnetic wave radiated from the noise erasing antenna 16 to the blowing portion of the plasma 14 and erasing the noise radiated from the plasma 14. In addition, in the example of FIG. 7, although the example comprised by the circular short cylindrical body is shown as the opening 27 which derives electromagnetic waves outside, as shown in FIG. 8, the square hole arrange | positioned in the position shown in figure You may comprise.

  In the above embodiment, an example in which the plasma head 2 includes the reaction tube 11 and the antenna 6 has been shown. However, as shown in FIG. 9, the plasma head 2 reacts around the lower end 11 b of the reaction tube 11. A cylindrical or rectangular mixed gas container 28 extending downward from the lower end 11b of the pipe 11 is disposed, and a plurality of gas supply ports 29 for supplying the mixed gas 33 to the inside are disposed at the upper part of the peripheral wall. The mixed gas region 30 is formed in the mixed gas container 28 by supplying the mixed gas 33 from the gas supply port 29, and the plasma 14 blown out from the reaction tube 11 collides with the mixed gas region 30. The configuration may be such that the secondary plasma 31 is generated, and the secondary plasma 31 is blown out from the lower end opening of the mixed gas container 28 to irradiate the surface 32 to be processed. Also in the case of such a plasma head 2, noise emission can be similarly prevented by applying the present invention.

  Further, as shown in FIG. 10A, the reaction space is not limited to the plasma head 2 in which high frequency power is applied by the coiled antenna 6 to generate the inductively coupled plasma 14 as described above. A pair of electrodes 43a and 43b are disposed on both sides of the substrate 41 via a dielectric 42, a high frequency voltage is applied between the electrodes 43a and 43b, and a gas (inert gas or inert gas) is applied from one end of the reaction space 41. The same effect can be obtained by applying the present invention to the plasma head 2 configured to blow out the capacitively coupled plasma 45 from the other end of the reaction space 41 by supplying a mixed gas 44 of gas and reactive gas). Can be played.

  Further, as shown in FIG. 10B, a pair of electrodes 47a and 47b are arranged on the outer periphery of a reaction tube 46 made of a dielectric material with an interval in the axial direction, and a high-frequency voltage is applied between the electrodes 47a and 47b. The plasma 45 may be blown out from the other end of the reaction tube 46 by applying and supplying the gas 44 from one end of the reaction tube 46. Further, as shown in FIG. 10C, a pair of electrodes 49a and 49b are arranged on the outer periphery of a reaction tube 48 made of a rectangular dielectric material having a long and narrow cross-sectional shape with a space in the axial direction, and the electrode 49a 49b, a high-frequency voltage may be applied between them.

  Further, as shown in FIG. 10 (d), an inner electrode 51 is disposed inside a reaction tube 50 made of a dielectric, an outer electrode 52 is disposed on the outer periphery, and a high frequency voltage is applied between the electrodes 51 and 52 to react. A configuration may be adopted in which plasma 45 is generated in the reaction tube 50 by supplying gas into the tube 50 and blown out from the blowing port 53. Furthermore, as shown in FIG. 10 (e), the tip of the inner electrode 54 is conical, the outer surface of the conical portion 55 is covered with a dielectric 56, and the outside is surrounded by a reaction space 57. An outer electrode 58 formed with a blowout opening 60 is disposed opposite to the tip of the conical portion 55, and gas is supplied into the space 57 from a gas supply passage 59 formed in the outer electrode 58, and the inner electrode 54 and A configuration may be adopted in which a high-frequency voltage is applied between the outer electrodes 58 to generate plasma in the reaction space 57 and blow out from the blow-out port 60. Further, various other configurations can be applied as the plasma head 2.

  Note that the present invention is not limited to the above-described embodiment, and with the configuration shown in the second embodiment, the noise level is continuously measured by the noise measuring unit 21, and the measured value of the noise measuring unit 21 is measured. The phase circuit 17 and the amplifier 18 may be controlled continuously or intermittently so that is less than a predetermined value. The measured value of the noise measuring means 21 changes greatly depending on the position of the plasma head 2 and the surrounding environment, and the phase circuit 17 and the amplifier 18 may be controlled following the changed value. .

  Further, the arrangement position of the noise measuring means 21 is not limited to that shown in the above embodiment, and may be arranged at a position where noise is desired to be reduced. Further, the number of noise canceling antennas 16 is not limited to one, and a plurality of noise canceling antennas 16 are arranged, and corresponding noise canceling voltage applying means, phase circuits, amplifiers, etc. are provided to lower the measurement value by the noise measuring means 21. You may do it.

  According to the atmospheric pressure plasma generation method and apparatus of the present invention, noise is measured in the vicinity of the plasma generation position, and a predetermined phase difference is applied to the noise canceling antenna disposed in the vicinity of the plasma generation position so that the noise approaches the minimum. By generating a noise canceling radio wave by supplying a high frequency voltage having a predetermined amplitude, it is possible to reliably erase even a variety of generated noise with a noise canceling radio wave set and adjusted to correspond to it. It is possible to reliably prevent various noises generated during the generation process of atmospheric pressure plasma from being released to the surroundings, so that various atmospheric pressure plasma generators, especially small atmospheric plasma generators mounted on various devices, can be generated. It can utilize suitably for an apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS The whole block diagram of 1st Embodiment of the atmospheric pressure plasma generator of this invention. Explanatory drawing of the adjustment setting process of the phase circuit and amplifier in the embodiment. The structural example of the phase circuit in the embodiment is shown, (a), (b) is a figure which shows a phase switching state. Explanatory drawing of the phase state in each site | part in the embodiment. The whole block diagram of 2nd Embodiment of the atmospheric pressure plasma generator of this invention. The block diagram of the structural example of the phase circuit of the same embodiment, and a control part. The whole block diagram of 3rd Embodiment of the atmospheric pressure plasma generator of this invention. The perspective view which shows the modification structural example of the plasma head of the embodiment. The longitudinal cross-sectional view which shows the modification structural example of the plasma generation part applicable to each embodiment of this invention. The other various modified structural examples of the plasma generation part applicable to each embodiment of this invention are shown, (a)-(c) is a perspective view, (d), (e) is a longitudinal cross-sectional view. The schematic block diagram of the atmospheric pressure plasma generator of the 1st prior art example. The block diagram of the matching circuit of the prior art example. The external appearance perspective view of the conventional example. Explanatory drawing of the noise level and the output of a reflected wave at the time of plasma lighting and extinguishing in the conventional example. The block diagram of the atmospheric pressure plasma generator of the 2nd prior art example. The high frequency voltage waveform applied to an electrode is shown, (a) is waveform explanatory drawing of a comparative example, (b) is waveform explanatory drawing in the prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Atmospheric pressure plasma generator 2 Plasma head 3 High frequency generation part 6 Antenna 7 Matching circuit 11 Reaction tube 12 Gas supply part 13 Gas 14 Plasma 15 Shielding cover 16 Noise elimination antenna 17 Phase circuit 18 Amplifier 19 Noise elimination voltage application means 20 Control part 21 Noise measurement means

Claims (10)

A plasma generation step of generating a plasma by supplying a gas to a reaction space near atmospheric pressure and applying a high-frequency voltage;
A noise canceling radio wave generating step of generating a noise canceling radio wave by supplying a high frequency voltage having a predetermined phase difference and a predetermined amplitude at the same frequency as the high frequency voltage to a noise canceling antenna disposed in the vicinity of the plasma generation position. Have
The method for generating atmospheric pressure plasma, wherein the predetermined phase difference and the predetermined amplitude are set in advance so that noise measured in the vicinity of the plasma generation position is minimized or in the vicinity thereof.   2. The atmospheric pressure plasma generation method according to claim 1, wherein the predetermined phase difference and the predetermined amplitude are changed when the plasma is turned on and off. A plasma generation step of generating a plasma by supplying a gas to a reaction space near atmospheric pressure and applying a high-frequency voltage;
A noise canceling radio wave generating step of generating a noise canceling radio wave by supplying a high frequency voltage having a predetermined phase difference and a predetermined amplitude at the same frequency as the high frequency voltage to a noise canceling antenna disposed in the vicinity of the plasma generation position. Have
An atmospheric pressure plasma generation method, wherein the predetermined phase difference and the predetermined amplitude are controlled so that noise measured in the vicinity of the plasma generation position is minimized or in the vicinity thereof.   4. The atmospheric pressure plasma generation method according to claim 1, wherein the high-frequency voltage is an RF frequency band, a VHF frequency band, or a microwave frequency band. A plasma head having a reaction space near atmospheric pressure and an antenna or electrode disposed in the vicinity of the reaction space;
A gas supply unit for supplying gas to the reaction space;
A high frequency generator for applying a high frequency voltage to the antenna or electrode;
A matching circuit that is disposed between the high-frequency generator and the antenna or electrode and adjusts the reflected power from the antenna or electrode;
A noise canceling antenna disposed in the plasma head or in the vicinity of the outside;
A noise erasing voltage applying means for applying a high frequency voltage having the same frequency as the high frequency voltage and having a predetermined phase difference and a predetermined amplitude to a noise erasing antenna;
The predetermined phase difference and the predetermined amplitude at which the noise measured near the plasma generation position is minimized or in the vicinity thereof are set in advance, and control for controlling the high frequency voltage output from the noise erasing voltage applying means based on the set value And an atmospheric pressure plasma generator.   6. The atmospheric pressure plasma generation apparatus according to claim 5, wherein the control unit changes the predetermined phase difference and the predetermined amplitude between when the plasma is turned on and when the plasma is turned off. A plasma head having a reaction space near atmospheric pressure and an antenna or electrode disposed in the vicinity of the reaction space;
A gas supply unit for supplying gas to the reaction space;
A high frequency generator for applying a high frequency voltage to the antenna or electrode;
A matching circuit that is disposed between the high-frequency generator and the antenna or electrode and adjusts the reflected power from the antenna or electrode;
A noise canceling antenna disposed in the plasma head or in the vicinity of the outside;
A noise erasing voltage applying means for applying a high frequency voltage having the same frequency as the high frequency voltage and having a predetermined phase difference and a predetermined amplitude to a noise erasing antenna;
A control unit that controls the high-frequency voltage output from the noise erasing voltage application means so that the noise measured near the plasma generation position is the minimum or near the predetermined phase difference and the predetermined amplitude. An atmospheric pressure plasma generator characterized by. The plasma head includes a primary plasma generation unit that includes the reaction space and an antenna or an electrode to generate primary plasma, and a mixed gas of an inert gas and a reactive gas that is introduced into a space communicating with the reaction space. The atmospheric pressure plasma generation according to any one of claims 5 to 7, further comprising a secondary plasma generation unit that generates a secondary plasma by colliding the primary plasma with a second gas. apparatus. The plasma head is covered with a shielding cover made of a metal material except for the portion for injecting the primary plasma or the secondary plasma and the portion for supplying the gas and the second gas, and has a matching circuit incorporated therein. The atmospheric pressure plasma generator according to claim 8, wherein:   The atmospheric pressure plasma generator according to any one of claims 5 to 9, wherein the noise canceling antenna is disposed in the vicinity of the antenna or the electrode and is built in the plasma head.

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