JP4963360B2 - Portable atmospheric pressure plasma generator - Google Patents

Description

  The present invention relates to a portable atmospheric pressure plasma generator capable of diverting a small cylinder that can stably generate plasma even with a small gas flow rate.

  At present, in atmospheric pressure plasma generators, high-power plasma torches that apply the thermal action of plasma, corona discharges and dielectrics that make use of so-called non-thermal equilibrium, high electron temperature, low density and low thermal load Barrier discharge plasma generators are the mainstream.

  Even in a non-thermal equilibrium state where the neutral gas temperature is much lower than the electron temperature, the temperature of the neutral gas reaches several hundred degrees, so in the case of a plasma torch with a nozzle inner diameter of about 1 cm, helium gas is several tens of liters per minute to have a cooling effect. The current situation is also flowing.

  Regarding the plasma torch in a non-thermal equilibrium state, there are proposals in Patent Documents 1 and 2.

The technique proposed in Patent Document 1 is “having a cylindrical discharge portion in which one or a plurality of cylindrical discharge spaces are formed between a high-voltage electrode and a ground electrode with a dielectric applied to or opposite to the electrode surface. A reaction gas composed of a monomer gas corresponding to the film forming species or a plasma gas corresponding to the process and an inert gas flows in from the gas introduction part upstream of the cylindrical discharge part and passes through the cylindrical discharge space. From the outlet provided on the downstream side of the discharge part, consisting of a structure that jets to the surface of the object to be treated,
A blowout that is excited by plasma when a reactive gas passes through a cylindrical discharge space where a high voltage is applied between the electrodes and glow discharge or silent discharge is performed near atmospheric pressure, and film formation or surface modification is performed on the surface of the material to be processed. A mold surface treatment apparatus.

  Further, the technique proposed in Patent Document 2 is an improvement of the technique of Patent Document 1, and “a metal tube provided with a tip at the outlet end edge is used as a high-voltage electrode, and the outlet of this high-voltage electrode metal tube” More inert gas and / or air, or a mixed gas of these and reactive gas is blown out to apply a voltage to the high-voltage electrode metal tube to generate a discharge with respect to the stray capacitance under atmospheric pressure, and plasma "Atmospheric pressure blowing plasma reactor".

  According to the above Patent Documents 1 and 2, the usefulness of surface modification and deposition is recognized for plasma processing at atmospheric pressure.

  However, since the degree of surface modification and deposition strongly depends on the excited state of the gas in the plasma, the processing energy (excitation gas energy) and processing time (excitation gas irradiation amount) are determined depending on the object to be processed, the gas species and the atmosphere. If the gas is not properly selected, desired surface treatment accuracy and reproducibility cannot be obtained. Excessive plasma irradiation also dissolves the sample base material and generates unnecessary reaction products.

  In order to increase the processing time using an atmospheric pressure plasma source that is easy to carry, the gas flow rate must be reduced according to the effective volume of the limited gas cylinder.

  In this case, the vicinity of the discharge part is heated, and it begins to adversely affect the stabilization of the plasma, such as deformation of the electrode structure and impurities released from the material of the discharge part. In addition, since the discharge voltage at the time of plasma generation increases, the apparatus becomes larger due to the increase in power supply capacity, making it difficult to carry. This problem can be alleviated by Patent Document 3, but becomes expensive because a new high-frequency power source for ignition is required. Furthermore, the power supply structure is complicated, and it is difficult to configure the system as a portable plasma source.

  Moreover, in the current general apparatus, the plasma generation power and gas supply lines are separate systems, and the workability cannot be said to be good.

Japanese Patent No. 2589599 Japanese Patent No. 3207469 JP 2002-008894 A

  An object of the present invention is to provide a portable atmospheric pressure plasma generator capable of stabilizing a desired gas excitation state with a small gas flow rate while improving the conventional thermal equilibrium type plasma torch technology. It is another object of the present invention to provide a portable atmospheric pressure plasma generator capable of downsizing the system by facilitating ignition and reducing power supply capacity by mechanical improvement of only the plasma torch tip.

1 of the present invention is a ground electrode disposed on the outer peripheral portion of the outer insulating tube so as to be movable in the axial direction;
An auxiliary electrode having the same potential as that of the ground electrode, disposed at the outer periphery of the outer insulating tube,
An inner insulating pipe disposed along the axis of the outer insulating pipe;
A high-speed nozzle for gas introduction disposed at the rear end of the external insulating tube;
A power electrode arranged in the inner insulating tube and configured to bring a part or the whole into contact with a plasma gas generated by ionizing a gas introduced from the high-speed nozzle; and
A plasma gas outlet opening at the tip of the outer insulating tube;
A gas supply unit that supplies a gas for generating plasma to the high-speed nozzle;
A programmable high-frequency power source that supplies high-frequency power for discharge between the ground electrode and the auxiliary electrode and the power electrode,
The ground electrode can be moved from a position closest to the tip of the power electrode to a position as close to the auxiliary electrode as necessary to avoid the power electrode from becoming hot, and during plasma ignition, A portable atmospheric pressure plasma generator characterized in that a ground electrode is positioned closest to the tip of the power electrode .

According to the second aspect of the present invention, in the portable atmospheric pressure plasma generator according to the first aspect of the present invention, a pulse bias voltage is applied between the power electrode and a workpiece to be processed by a pulse bias power source. It is a thing.

In the portable atmospheric pressure plasma generator 1 or 2 of the present invention, 3 of the present invention is for observing the light emission state in the vicinity of the outlet of the outer insulating tube to the tip of the outer insulating tube. It is an extension of the optical fiber conduit.

A fourth aspect of the present invention is the portable atmospheric pressure plasma generator according to the third aspect of the present invention, wherein the optical fiber conduit is connected to a spectroscopic analyzer, and the gas excitation state around the outlet is spectroscopically monitored by the spectroscopic analyzer. The obtained excited state data is compared with the reference excited state data, so that a desired gas excited state is obtained, the high frequency voltage / current waveform of the programmable high frequency power source, the gas species mixing ratio supplied by the gas supply unit, and It is configured to control various gas flows.

  According to the portable atmospheric pressure plasma generator 1 of the present invention, it is possible to irradiate the surface of the object with higher energy positive ions using the same atmospheric pressure plasma excitation power source as in the prior art. Even at the flow rate, the plasma can be extracted from the outlet longer. It is also possible to obtain a large-area atmospheric pressure plasma source by bundling this plasma torch.

  According to the portable atmospheric pressure plasma generating apparatus 2 of the present invention, a function of accelerating ions and strongly impacting the object to be processed is required, for example, when roughing the surface of the object to be processed without excessive heating. It is effective in the case. A pulse bias should be applied between the power electrode and the workpiece to be processed while the carrier wave of the programmable high-frequency power supply is paused. This can be easily performed by a non-contact relay using a semiconductor element or the like. Can be configured.

  According to the portable atmospheric pressure plasma generator 3 of the present invention, the light emission state in the vicinity of the plasma blowout port from the blowout port at the tip can be observed well, and when the plasma is generated and extinguished, Excited states can also be observed.

  According to the portable atmospheric pressure plasma generator 4 of the present invention, the high-frequency voltage / current waveform of the programmable high-frequency power source, the mixing ratio of the gas species supplied by the gas supply unit, and various gas flows are appropriately controlled. Since it is possible, a desired gas excitation state can be obtained reliably.

  FIG. 1 is an explanatory diagram showing the portable atmospheric pressure plasma generator of the present invention and the entire system including the same. This system is roughly divided into a plasma generation device / spectral analysis system A, a multi-flexible feeder system B, and a plasma generation / light detection system (portable atmospheric pressure plasma generator) C as viewed from the upstream side of the gas flow.

  As shown in FIG. 1, the plasma generating device / spectral analysis system A includes a plasma generating programmable high-frequency power supply unit A-1, a pulse bias power supply unit A-2, a spectral analysis unit A-3, and a gas. A supply unit A-4 and a personal computer (hereinafter abbreviated as PC) unit A-5 are included.

  The programmable high frequency power supply unit A-1 employs one that can generate a burst-like voltage waveform as shown in FIG. This is a power source for discharge, and is supplied between the power electrode 3 of the discharge section C-1 and the movable ground electrode 4 and auxiliary electrode 4a, and controls the plasma density, space potential, and electron temperature. The waveform is in a burst shape as described above. From the above viewpoint, the amplitude, the carrier frequency, the repetition frequency, and the duty ratio can be appropriately controlled. For example, those capable of controlling these in a range of 0 to 2 kV, 1 to 20 MHz, 1 kHz to 100 kHz, and 5 to 95% are suitable.

  The pulse bias power supply unit A-2 controls the bias voltage and thereby controls the ion bombardment energy, and the power electrode 3 and the conductor of the discharge unit C-1 described later in the portable atmospheric pressure plasma generator C A pulse voltage in which the former is a high voltage and the latter is a low voltage is applied to the object to be processed. The output waveform is suitably configured so that it can be controlled in the range of amplitude 0 to 6 kV, pulse width 0 to 100 μs, and repetition frequency 1 kHz to 100 kHz, for the above purpose. As described above, the repetition frequency is applied to the programmable high-frequency power supply unit A-2 in order to apply it between the power electrode and the workpiece to be processed while the carrier of the programmable high-frequency power supply unit A-2 is stopped. Correspond with that of -1.

  As the spectroscopic analysis unit A-3, for example, a unit having 1024 diffraction gratings and a CCD array 1024ch and having an exposure time in the range of 40 ms to 20 s can be adopted.

  The gas supply unit A-4 can be composed of a gas cylinder, a valve disposed in the opening thereof, and a controller for controlling the valve. The gas cylinder should be determined in relation to the portable atmospheric pressure plasma generator C. In relation to the planned gas cylinder, for example, the gas cylinder has a size within 350, 80, and 80 mm and has a gas pressure resistance of 20 MPa. The thing used by specification can be adopted. The pressure reducing valve attached to the gas cylinder is provided with pressure sensors on the primary side and the secondary side, and it is appropriate that each pressure value can be monitored successively by the PC section A-5. Also, as the valve, for example, a piezo-type valve is adopted, a mass flow controller is incorporated as a controller, and the valve opening and closing and the gas flow range of 0.05 to 5 l / min (1 atm, 0 ° C) are controlled by the PC section A-5. It can be so. Of course, these are determined in relation to the planned portable atmospheric pressure plasma generator C.

  As the PC unit A-5, for example, a general one having a performance of CPU: PENTIUM (registered trademark) 4-3 GHz and memory: 512 MB or more can be adopted. It is appropriate that each part in the plasma generating apparatus / spectral analysis system A is incorporated in one box. For example, as shown in FIG. 1, only the PC part A-5 is placed outside the box. And connecting each other with communication standards such as USB, RS-232C, GP-IB, and controlling other components in the plasma generating apparatus / spectroscopy system A including the interlocking relays 10a and 10b described later. It can also be.

  The multi-flexible feeder system B includes a plasma generation power supply line section B-1, a gas supply line section B-2, a fiber light transmission line section B-3, and a pulse bias voltage application line section B-4. Consists of. As shown in FIG. 2, for example, they are arranged concentrically to form a single flexible line, and considering the convenience of use, the total length is usually within 3 m and the allowable curvature is about 10 cm. Is appropriate.

  The power supply line section B-1 is arranged concentrically with the mesh-shaped power sleeve B-1b and the mesh-shaped power sleeve B-1b in the same manner as the mesh-shaped grounding sleeve B-1a, with the former on the outside and the latter on the inside. Are each held by a flexible insulating material, for example, a PTFE (polytetrafluoroethylene) tube (insulating sleeve). Each dimension is not limited to a specific one, but the thickness of the insulating material is assumed to be about 0.5 mm, and power to be supplied and a gas introduction pipe B-2a constituting a gas supply line section B-2 to be described later and In consideration of the above relationship, it is appropriate that the inner diameter of the ground sleeve B-1a is 6 mm, the thickness is 0.2 mm, the inner diameter of the power sleeve B-1b is 3.8 mm, and the thickness is 0.2 mm. It is.

  Needless to say, the power sleeve B-1b and the ground sleeve B-1a of the power supply line section B-1 include a power electrode 3 and a ground electrode 4 which will be described later, respectively. Are electrically connected to the programmable high frequency power supply unit A-1 for generating plasma. The auxiliary electrode 4a described later is connected in parallel with the ground electrode 4. In addition, the power electrode 3 and the programmable high frequency power supply unit A-1 are connected via one interlocking relay 10a as shown in FIG. 3 (b).

  As the gas introduction pipe B-2a constituting the gas supply line section B-2, various pipe materials can be used. For example, a PTFE pipe is adopted, and these are provided inside the power supply line section B-1. And can be arranged closely in a concentric manner. When the power supply line section B-1 is composed of the ground sleeve B-1a, the power sleeve B-1b, and the insulating material between and around the outer periphery as described above, the gas introduction pipe B-2a It is appropriate to arrange in such a manner that it is in close contact with the inner side of the innermost power sleeve B-1b.

  In the multi-flexible feeder system B, the fiber optical transmission line part B-3 is between the power supply line part B-1 and the gas introduction pipe B-2a constituting the gas supply line part B-2 or It can distribute | arrange in any site | part of those outermost peripheral parts. Of course, it is arranged between the above two by using a groove formed along the length direction on the outer surface of a pipe material such as a PTFE pipe constituting the gas introduction pipe B-2a. This is advantageous because the conduits can be arrayed.

  In this case, a plurality of grooves are formed on the outer surface of the gas introduction pipe B-2a constituting the gas supply line section B-2 at a constant angular interval in the circumferential direction and in the direction along the length direction. An optical fiber conduit is embedded in the groove, thereby forming a fiber optical transmission line portion B-3. When a PTFE pipe is used as the gas introduction pipe B-2a, as described above, the optical fiber conduit has a room to be arranged as described above, and therefore has a corresponding peripheral wall thickness. Needless to say, it should be.

  The pulse bias voltage application line portion B-4 can also be used as the power sleeve B-1b of the power supply line portion B-1. As a result, the manufacturing process can be simplified and the cost can be reduced. However, if the length of the multi-flexible feeder system B is several meters, the line capacity of the power supply line section B-1 will increase, and if this is also used, the pulse waveform will be lost. It should be done. In this case, a single conductor is insulated and coated between the power supply line section B-1 of the multi-flexible feeder system B and the gas introduction pipe B-2a constituting the gas supply line section B-2, or at the end thereof. It can be routed to any part of the outer periphery.

  The single-wire conductor is arranged together with the optical fiber conduit in the groove formed along the length direction on the outer surface of the gas introduction pipe B-2a in the same manner as the fiber optical transmission line section B-3. It is also possible to do so. In this case, the conducting wire is arranged in parallel between these two optical fiber conduits adjacent to each other in the circumferential direction.

  The pulse bias voltage applying line section B-4 is connected to the power electrode 3 to be described later on the plasma generating discharge section C-1 via the other interlocking relay 10b on the high voltage side of the pulse bias power supply section A-2. To do. The low voltage side of the pulse bias power supply unit A-2 is connected to the object to be processed by a conductive wire extending from here. When pulse bias is used in combination, the interlocking relay 10a and the interlocking relay 10b are complementary to the zero voltage interval indicated by the voltage waveforms of the programmable high frequency power supply A-1 and the pulse bias power supply unit A-2. It is assumed that the relay drive is set appropriately so that power can be supplied. In the above manner, the plasma state is maintained for several μs immediately after the plasma generating carrier wave is stopped. Therefore, if the rest time of the carrier for plasma generation is set to several μs, the plasma state is maintained while the pulse bias voltage is applied as described above. As described above, it is effective to apply a pulse bias using the above structure when a function for accelerating ions and strongly impacting the object to be processed is required. In addition, these interlocking relays 10a and 10b can be constituted by semiconductor elements. The operation of the interlocking relays 10a and 10b can be controlled by the PC unit A-5 as described above.

The application of the above pulse bias is based on the following experimental results.
A choke coil is inserted between the pulse bias power source A-2 and the interlocking relay 10b and between the pulse bias power source A-2 and the movable ground electrode 4, and one interlocking relay 10a is used as a capacitor. Instead, when the other interlocking relay 10b is closed at the same time and a DC bias (-300V) is applied between the power electrode 3 and the workpiece (stainless steel SUS304) for several seconds, the surface of the workpiece is Particle impact marks (on the order of several μm in depth) of particles considered to be positive ions contained in the torch-like plasma generated continuously immediately before the application of the DC bias were observed.

From the above results, it is best to apply a high voltage pulse (for example, 5 kV, 20 μs, 10 kHz) instead of the above-mentioned DC bias in order to roughen the surface at high speed while suppressing overheating of the workpiece. It is self-evident.

  Furthermore, the fiber light transmission line part B-3 is connected to the spectroscopic analysis part A-3 so as to transmit light detected by the light detection part C-2 described later for detecting plasma emission.

  The portable atmospheric pressure plasma generator C, which is the plasma generation-light detection system, includes a discharge unit C-1 for generating plasma and a light detection unit C-2 for detecting plasma emission. As shown in FIG. 3 (b), these are arranged to be arranged in a cylindrical outer insulating tube 8 and a small-diameter inner insulating tube 9 arranged along the axis.

  The discharge section C-1 for generating plasma is composed of a power electrode 3, a movable ground electrode 4, an auxiliary electrode 4a, and a high-speed nozzle for introducing gas. It is attached to the insulating tube 8 and the internal insulating tube 9.

  The power electrode 3 is configured, for example, as an L-shaped central conductor, and as shown in FIG. 3 (b), the axial direction portion 3a is inserted into the internal insulating tube 9, and from the rear end of the central conductor. The vicinity of the outer end of the vertical portion 3b extending in the perpendicular direction is set on the outer insulating tube 8. A locking groove is formed in the outer insulating tube 8 in the axial direction from the rear end, and the vicinity of the outer end of the vertical portion 3b is inserted into the locking groove so as to contact the downstream end thereof. It is appropriate to arrange. In this case, as described above, the inner insulating tube 9 is coaxially fixed and held on the outer insulating tube 8 through the longitudinal portion 3b of the central conductor constituting the power electrode 3 disposed thereon. It will be.

  The outer insulating tube 8 and the inner insulating tube 9 can be made of, for example, quartz glass.

  The movable ground electrode 4 is formed as an annular conductor, and as shown in FIGS. 3 (a) and 3 (b), is externally slidably provided on the outer periphery of the outer insulating tube 8 along its axial direction. . The sliding range of the ground electrode 4 is set so that the power electrode 3 can be moved to the distal end side of the outer insulating tube 8 as much as necessary to avoid a high temperature. For example, the power electrode 3 is configured so as to be reciprocally movable by approximately 10 mm from the vicinity corresponding to the inside and outside of the power electrode 3 to the distal end side of the external insulating tube 8. The configuration for reciprocal movement is free.

  The auxiliary electrode 4a is arranged in parallel with the ground electrode 4 as described above. The auxiliary electrode 4a is formed as an annular conductor, like the ground electrode 4, and is externally fixed to the outer periphery of the distal end of the external insulating tube 8 as shown in FIG. The auxiliary electrode 4a is covered with an insulating jacket 14 fixed to the outer insulating tube 8 on the tip side. The insulating jacket 14 is also preferably made of quartz glass. It is also possible to make the tip of the outer insulating tube 8 thin at the tip of the plasma outlet, and accordingly, make the ring outer diameter of the auxiliary electrode 4a smaller than that of the ground electrode 4.

  The light detection part C-2 for detecting the plasma emission can be composed of a plurality of optical fiber conduits 5, 5... Extending from the rear end to the front end of the outer insulating tube 8. Although it can be arranged over the outer peripheral portion of the outer insulating tube 8, as shown in FIGS. 3 (a) and 3 (b), the outer insulating tube 8 has a configuration in which it is arranged at constant angular intervals in the peripheral thick portion. Is more preferable. At this time, the tip of each optical fiber conduit 5, 5... Is as close as possible to the tip of the external insulating tube 8. The optical fiber conduits 5, 5... Can be arranged in the peripheral thick portion of the outer insulating tube 8 by forming the outer insulating tube 8 and then embedding the conduit therein. .

  The high-speed nozzle is configured at the rear end of the outer insulating tube 8, that is, at the center of the upstream end. As this high speed nozzle, various supersonic nozzles can be adopted. For example, as shown in FIG. 3 (b), a cylindrical Laval nozzle 1 can be fitted into the rear end of the outer insulating tube 8.

  As shown in FIG. 3B, the distal end of the external insulating tube 8 is in an open state as it is and serves as a plasma gas outlet.

  Therefore, according to this system including the portable atmospheric pressure plasma generator of the present invention, as described above, the programmable high-frequency power supply unit A-1 having the same specifications as those of the conventional atmospheric pressure plasma excitation power supply is used. The surface of the workpiece can be irradiated with positive ions of energy.

  In addition, the gas supplied from the gas supply unit A-4 of the plasma generation device / spectroscopy system A to the portable atmospheric pressure plasma generator C through the multi-flexible feeder system B constitutes the discharge unit C-1 through the high-speed nozzle. It is introduced into the outer insulating tube 8 at a high speed. Thus, even when the gas introduced into the outer insulating tube 8 is at a low flow rate, the dielectric barrier discharge part is well plasmified, and the generated plasma is longer from the outlet at the tip of the outer insulating tube 8. Can be withdrawn. In other words, in addition to the ground electrode 4 movably arranged in the middle of the outer periphery of the outer insulating tube 8, an auxiliary electrode 4a is arranged on the outer periphery of the tip, and output from the programmable high frequency power source A-1 between these and the power electrode Since the high frequency voltage to be applied is applied, the electric field line density near the tip of the outer insulating tube 8 is increased, and the seed plasma from the dielectric barrier discharge portion located upstream thereof is spatially increased to increase the density of the seed plasma. Atmospheric pressure plasma can be drawn out of the outlet.

  In addition, since the optical fiber conduits 5, 5... Are extended to the tip of the outer insulating tube 8, the plasma emission state in the vicinity of the outlet at the tip is detected well, and this is used for generating plasma through the multi-flexible feeder system B. It is transmitted to the spectroscopic analysis unit A-3 of the instrument / spectrometric analysis system A, and the gas excited state in the plasma and the excited state of the surface of the object to be processed are observed, and this observation result data is input to the PC unit A-5. In the PC unit A-5, the observation result data is compared with the reference state data which is the data of the desired gas excitation state, and based on the comparison result, the amplitude, frequency, etc. of the programmable high frequency power supply unit A-1 The output waveform, the mixing ratio of the gas species supplied from the gas supply unit A-4, the flow rate of each gas species, and the like are appropriately controlled to ensure a desired gas excitation state.

  Further, as described above, the ground electrode 4 arranged on the outer periphery of the outer insulating tube 8 is configured to be movable in the axial direction of the outer insulating tube 8 so that the ground electrode 4 can be brought close to the power electrode 3 when the plasma is ignited. It is possible to move and thereby obtain a relatively low discharge start voltage, and by cooling the power electrode 3 by narrowing the nozzle diameter of the high-speed nozzle, the plasma can be stably maintained at a low gas flow rate.

  Thus, the programmable high frequency power source A-1 for generating plasma and the gas cylinder of the gas supply unit A-4 can be miniaturized, and a small system including a small portable atmospheric pressure plasma generator can be provided.

In addition, according to this system including the portable atmospheric pressure plasma generator of the present invention, a pulse bias is applied between the power electrode and the workpiece to be processed while the carrier wave of the programmable high frequency power supply is stopped. By accelerating the ions and bombarding the workpiece,
The surface can be roughened without excessive heating.

  This embodiment relates to a system including the portable atmospheric pressure plasma generator of the embodiment, and the outline of the overall configuration is as shown in FIG.

  As shown in FIG. 1, this system is composed of a plasma generating device / spectral analysis system A, a multi-flexible feeder system B, and a portable atmospheric pressure plasma generator C as viewed from the upstream side of the gas flow. Is.

  As shown in FIG. 1, the plasma generating device / spectral analysis system A includes a plasma generating programmable high-frequency power supply unit A-1, a pulse bias power supply unit A-2, a spectral analysis unit A-3, and a gas. It comprises a supply unit A-4 and a PC unit (personal computer unit) A-5.

  The programmable high frequency power supply A-1 generates a burst-like voltage / current waveform as shown in FIG. 4 (a), and its amplitude, carrier frequency, repetition frequency, and duty ratio are 0 to 2 kV, 1 to It is configured to be controllable in the range of 20 MHz, 1 kHz to 100 kHz, and 5 to 95%.

Explaining this in detail, the programmable high-frequency power supply unit A-1 refers to the effective value output as the amplitude, which can be controlled in the range of 0 to 2 kV as described above. The carrier frequency is the reciprocal of the period t shown in FIG. 4A (1), and can be controlled in the range of 1 to 20 MHz as described above. The repetition frequency is the reciprocal of the total time (t _on + t _off ) of the _on time and off time of the carrier shown in (1) of FIG. 4 (a), which is 1 kHz to 100 kHz as described above. It can be controlled in a range. Further, the duty ratio is a 100 fraction [100 t _on / (t _on + t _off )] of the _on time (t _on ) with respect to the total time (t _on + t _off ), which is 5 as described above. Control is possible in the range of ~ 95%.

  In the pulse bias power supply unit A-2, the former has a high voltage between the power electrode 3 of the discharge unit C-1 of the portable atmospheric pressure plasma generator C and the object 7 to be processed, and the latter is Connection is made so as to apply a pulse voltage that is a low voltage. The output waveform is configured such that it can be controlled in the range of amplitude 0 to 6 kV, pulse width 0 to 100 μs, and repetition frequency 1 kHz to 100 kHz.

  The spectroscopic analysis unit A-3 has a number of diffraction gratings of 1024, a CCD array of 1024ch, and an exposure time ranging from 40 ms to 20 s.

  The gas supply unit A-4 is composed of a gas cylinder, a valve disposed in the opening thereof, and a controller for controlling the valve. The gas cylinder used had an outer shape of 350, 80, and 80 mm and a gas pressure resistance of 20 MPa. The pressure reducing valve attached to the gas cylinder is provided with pressure sensors on the primary side and the secondary side so that each pressure value can be successively monitored by the PC section A-5. In addition, a piezo-type valve is adopted as the valve, and a mass flow controller is incorporated as a controller so that the valve opening and closing and the gas flow range of 0.05 to 5 l / min (1 atm, 0 ° C) can be controlled by the PC section A-5. It is a thing.

  The PC part A-5 adopts a general notebook type CPU having a performance of CPU: PENTIUM (registered trademark) 4-3 GHz, memory: 512 MB or more, and each part of the plasma generating apparatus / spectral analysis system A And connected to the USB communication standard to control other components in the plasma generation apparatus / spectroscopy system A including the interlocking relays 10a and 10b. .

  The multi-flexible feeder system B includes a plasma generation power supply line section B-1, a gas supply line section B-2, a fiber light transmission line section B-3, and a pulse bias voltage application line section B-4. Consists of. As shown in FIG. 2, they were concentrically arranged to form a single flexible line, with a total length of 3 m and an allowable curvature of 10 cm.

  As shown in FIG. 2, the power supply line section B-1 is concentric with a mesh-like power sleeve B-1b as well as a mesh-like ground sleeve B-1a, with the former on the outside and the latter on the inside. The outer periphery and the outer periphery thereof were respectively held by insulating sleeves B-1c and B-1c made of PTFE (polytetrafluoroethylene). The insulation sleeve B-1c has a thickness of 0.5 mm, the ground sleeve B-1a has an inner diameter of 6 mm, its thickness is 0.2 mm, the power sleeve B-1b has an inner diameter of 3.8 mm, and its thickness is 0.2 mm. 2 mm. In any case, the length is 3 m as described above.

  As the gas supply line section B-2, a PTFE gas introduction pipe B-2a is adopted. As shown in FIG. 2, the inside of the power supply line section B-1, that is, a power sleeve having an inner diameter of 3.8 mm. They were placed concentrically with B-1b in such a manner that they were inserted inside. This PTFE gas introduction tube B-2a has an inner diameter of 2 mm and a peripheral side thickness of 0.7 mm.

  The fiber optical transmission line part B-3 uses a groove disposed along the length direction on the outer surface of the PTFE gas introduction pipe B-2a constituting the gas supply line part B-2. The optical fiber conduits B-3a, B-3a,. As shown in FIG. 2, these optical fiber conduits B-3a, B-3a... Are arranged at a constant angular interval of 45 degrees in the circumferential direction in the groove on the outer surface of the gas introduction pipe B-2a. And it arranged in the direction along the length direction. These optical fiber conduits B-3a, B-3a,... Are formed after the gas introduction pipe B-2a is formed and then embedded in the grooves of the array.

  The optical fiber conduit B-3a described above has a diameter of 200 μm and a transmission wavelength of 200-950 nm.

  The pulse bias voltage application line section B-4 is a PTFE gas introduction pipe B-2a that constitutes the gas supply line section B-2 in the same manner as the fiber optical transmission line section B-3. By embedding it in a groove on the outer surface of this, a pulse bias voltage application line B-4a was constructed. In this case, the conducting wire constituting the pulse bias voltage applying line B-4a is arranged in parallel between the two optical fiber conduits B-3a and B-3a adjacent in the circumferential direction.

  The portable atmospheric pressure plasma generator C is composed of a discharge part C-1 for generating plasma and a light detection part C-2 for detecting plasma emission. As shown in FIG. 3 (b), these are arranged in a cylindrical outer insulating tube 8 and a small-diameter inner insulating tube 9 arranged along the axis.

  The discharge part C-1 is composed of a power electrode 3, a movable ground electrode 4, a fixed auxiliary electrode 4a, and a Laval nozzle 1 for gas introduction, and as described above, these are external insulating tubes. 8 and the inner insulating tube 9.

  In this embodiment, the power electrode 3 is configured as an L-shaped central conductor, and as shown in FIG. 3B, the axial direction portion 3a is inserted into the inner insulating tube 9, and the central conductor is The vicinity of the outer end of the vertical portion 3b extending in the direction perpendicular to the rear end is set on the outer insulating tube 8. A locking groove is formed in the outer insulating tube 8 from its rear end in the axial direction, and the vicinity of the outer end of the vertical portion 3b is inserted into the locking groove so as to contact the downstream end thereof. It is arranged in. As described above, in this embodiment, the inner insulating tube 9 is fixedly held coaxially to the outer insulating tube 8 via the longitudinal portion 3b of the central conductor constituting the power electrode 3 disposed thereon. It is supposed to be done.

  The outer insulating tube 8 and the inner insulating tube 9 are both made of quartz glass, and the outer insulating tube 8 has a straight cylindrical shape, as shown in FIG. Both the upstream end and the downstream end) are open, and the inner insulating tube 9 is closed at the front end (downstream end) and opened at the rear end (upstream end) as shown in FIG. It has a test tube configuration. In this embodiment, the outer diameter of the outer insulating tube 8 is 5.3 mm, the thickness of the peripheral side portion is 0.65 mm, the outer diameter of the inner insulating tube 9 is 2 mm, and the thickness is 0.5 mm. It is configured.

  The diameter of the L-shaped central conductor constituting the power electrode 3 is 0.5 mm, the length of the axial direction portion 3 a is 10 mm, and the length of the vertical direction portion 3 b is 3 mm.

  As shown in FIGS. 3 (a) and 3 (b), the movable ground electrode 4 is formed as an annular conductor, and is slidably provided on the outer periphery of the outer insulating tube 8 along its axial direction. . The sliding range of the ground electrode 4 is between the vicinity of the portion that substantially matches the inside and outside of the power electrode 3 and the portion on the tip (downstream end) side of the external insulating tube 8 by about 10 mm from the portion. This range is freely movable. The ground electrode 4 was 5 mm wide and 0.2 mm thick.

  The auxiliary electrode 4a is formed as an annular conductor, like the ground electrode 4, and is externally fixed to the outer periphery of the distal end of the external insulating tube 8 as shown in FIG. 8 is covered with an insulating jacket 14 made of quartz glass fixed to the front end side. The auxiliary electrode 4a has a downstream end located at a position retracted 1 mm upstream from the downstream end of the external insulating tube 8. The auxiliary electrode 4a is electrically connected in parallel with the ground electrode 4. The auxiliary electrode 4a has a width of 5 mm and a wall thickness of 0.2 mm, similar to the ground electrode 4.

  As shown in FIGS. 3A and 3B, the light detection unit C-2 for detecting the plasma emission has eight optical fiber conduits 5 extending from the rear end to the front end of the outer insulating tube 8 as shown in FIGS. In addition, the outer insulating tube 8 has a configuration in which the outer insulating tube 8 is arranged at a constant angular interval of 45 degrees in the circumferential direction in the thick portion on the peripheral side. At this time, the distal end portions of the optical fiber conduits 5, 5... Are close to the distal end (downstream end) of the outer insulating tube 8 up to 0.3 mm. The optical fiber conduits 5, 5... Are arranged in the peripheral side thick portion of the outer insulating tube 8 after the outer insulating tube 8 is molded, and the optical fiber conduits 5, 5. Was done by.

  The optical fiber conduits 5, 5,... Are those having a diameter of 200 μm and a transmission wavelength of 200-950 nm because the optical fiber conduit B-3a constituting the fiber optical transmission line section B-3 is used as it is. .

  As shown in FIG. 3 (b), the Laval nozzle 1 has a cylindrical outer shape and has a concave lens shape with a vertical cross section, and has a diameter of 0.2 mmφ at the center viewed from the end face direction and a depth (length). ) Is a product having a 0.5 mm nozzle hole. As described above, the outer insulating pipe 8 is concentrically fitted and fixed to the rear end, that is, the upstream end.

  As shown in FIG. 1, an outer shell C-3 having a larger diameter is coupled to the rear end (upstream side end) of the outer insulating pipe 8, and a gas flow switch C is connected to the outer shell C-3. -3a and gas excitation switch C-3b are arranged. The gas flow switch C-3a is a switch that opens and closes an opening / closing valve (not shown) arranged immediately before the Laval nozzle 1, and the gas excitation switch C-3b includes the programmable high-frequency power supply unit A-1 and the pulse bias. This is a switch for turning on / off the power supply unit A-2.

  The configuration of each part of the system including this portable atmospheric pressure plasma generator is as described above, but the flexible feeder system B is connected to the upstream plasma generating device / spectral analysis system A and the downstream as shown below. The system is completed by connecting to the portable atmospheric pressure plasma generator C.

  Thus, the power sleeve B-1b and the ground sleeve B-1a of the power supply line section B-1 respectively connect the power electrode 3, the ground electrode 4 and the auxiliary electrode 4a of the plasma generating discharge section C-1 to the programmable high frequency power supply section. Electrical connection to A-1. The power electrode 3 and the programmable high-frequency power supply unit A-1 are connected via an interlocking relay 10a as shown in FIG. 3 (b). This interlocking relay 10a includes a semiconductor element including the interlocking relay 10b described later.

  The pulse bias voltage application line section B-4 connects the power electrode 3 of the plasma generating discharge section C-1 and the high voltage side of the pulse bias power supply section A-2 via the interlocking relay 10b. The low voltage side of the pulse bias power supply unit A-2 is individually connected to the object to be processed 7 side with a lead wire separately extended from here. When the pulse bias is used together, the one interlocking relay 10a is opened at the time when the carrier wave of the programmable high frequency power supply A-1 is cut off, and at the same time, the other interlocking relay 10b is closed, so that only the pulse voltage is applied to the power electrode 3. Is supplied. In this case, the pulse width is smaller than the pause time of the carrier wave, and the repetition period is made to coincide with that of the burst voltage waveform. Such a pulse bias is applied when ions need to be accelerated and strongly bombarded to the object 7 when it is desired to roughen without excessively heating the surface of the object 7 to be processed. When the programmable high-frequency power source A-1 is configured to include the pulse having a large slew rate that is superimposed on the burst voltage waveform at the timing, the pulse bias power source unit A-2, the bias voltage application line unit B-4 and interlocking relays 10a and 10b are unnecessary.

  The fiber light transmission line part B-3 is connected at one end to the spectroscopic analysis part A-3, and the other end is extended as it is as a light detection part C-2 for detecting plasma emission.

  The gas supply line section B-2 is connected to the gas supply section A-4 at one end and connected to the upstream side of the Laval nozzle 1 at the other end.

  Next, a mechanism by which a desired gas excited state can be obtained by a system including the above portable atmospheric pressure plasma generator will be described with reference to FIGS.

  The gas flow switch C-3a is operated to open the on-off valve immediately before the Laval nozzle 1, and the gas excitation switch C-3b is turned on.

  Thus, helium gas is supplied from the gas cylinder of the gas supply unit A-4, and as shown by an arrow 6 in FIG. 3B, this is introduced up to the Laval nozzle 1 and through the Laval nozzle 1, 0.5 liters per minute. The helium gas is introduced into the central portion of the upstream end of the outer insulating tube 8 at a high speed at (0.5 l / min). At this time, the movable ground electrode 4 is moved to the upstream side so as to approach the axial portion 3a of the L-shaped central conductor as the power electrode 3. Thus, a relatively low discharge start voltage is obtained, and plasma ignition is facilitated with a small power source capacity. The ignited plasma can be stably maintained even at a low gas flow rate by cooling the power electrode 3 by narrowing the nozzle diameter with the Laval nozzle 1.

  At this time, the programmable high frequency power supply unit A-1 has a waveform as shown in (2) of FIG. 4A, that is, a voltage of 2 MHz, a carrier frequency of 2 MHz, an amplitude of 100 V, a repetition frequency of 100 kHz, and a duty ratio of 30%. A current waveform is generated and supplied between the power electrode 3, the movable ground electrode 4 and the auxiliary electrode 4a. When this amplitude is increased, the dielectric is between about 800 V and the ground electrode 4 located on the outer periphery of the outer insulating tube 8 and the power electrode 3 in the inner insulating tube 9 as shown in FIG. A body barrier discharge is generated, during which dielectric barrier discharge plasma 13 is generated.

  Next, by further increasing the amplitude of the high-frequency voltage / current output from the programmable high-frequency power supply unit A-1, as shown in FIG. 8 can be pulled out of the tip. Thus, the torch-like plasma 12 is generated as shown in FIG.

  Thereafter, the movable ground electrode 4 is moved away from the axial portion 3a of the L-shaped central conductor, which is the power electrode 3, and is brought closer to the auxiliary electrode 4a. In this way, it is possible to prevent the power electrode 3 from becoming high temperature and generating impurities.

  When plasma is generated by a waveform having a carrier frequency of 2 MHz, an amplitude of 900 V, a repetition frequency of 100 kHz, and a duty ratio of 30%, that is, the waveforms of FIGS. 4 (a)-(2), it is shown in FIGS. 4 (a)-(1). Compared to the case where the waveform is generated with a larger duty ratio, a plasma state having a lower electron temperature is realized.

  In this case, as shown in FIG. 4 (c), the energy necessary for chemical reaction such as ionization of nitrogen gas and dissociation of oxygen gas is specific to atoms and molecules, so oxygen molecules that are components of the atmospheric atmosphere. And nitrogen molecules are less likely to ionize.

  The gas excitation state in the above plasma is detected by the optical fiber conduits 5, 5... Embedded in the extended state up to the tip (downstream end) of the outer insulating tube 8, and this is detected as the fiber of the multi-flexible feeder system B. The light can be guided to the spectroscopic analysis part A-3 via the optical transmission line part B-3 and monitored by this.

  When monitored in this way, as shown in FIG. 4 (d) -2, it can be seen that the excitation spectrum of oxygen molecules having a wavelength of around 800 nm appears more intensely as a light emission phenomenon in the plasma gas.

  When the excited state of the nitrogen molecular gas is required, the programmable high frequency power supply unit A-1 controls the PC unit A-5 to generate a waveform output with a large duty ratio shown in FIGS. 4 (a)-(1). You just have to operate it. As a result, as shown in FIG. 4D, it can be seen that the excitation spectrum of nitrogen molecules having a wavelength of about 200 to 400 nm appears more intensely.

  Thus, the portable atmospheric pressure plasma generator C can control the excitation state of the plasma generation gas within a certain range by controlling the output waveform of the programmable high-frequency power supply unit A-1 according to the purpose.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the portable atmospheric pressure plasma generator of this invention, and the whole system containing this. Cross-sectional explanatory drawing which shows the outline | summary of the multi-flexible feeder of an Example. (a) is a cross-sectional explanatory view showing the plasma discharge structure and fiber light detection function in the main part of the portable atmospheric pressure plasma generator of the embodiment, (b) is the portable atmospheric pressure plasma generator of the embodiment. Side surface explanatory drawing explaining the plasma discharge structure and fiber light detection function which start. (a) is a diagram showing the output waveform of the programmable high-frequency power supply unit when generating plasma using the portable atmospheric pressure plasma generator of the embodiment, (b) is a diagram showing the energy distribution of plasma electrons corresponding to the waveform (C) is a figure which shows an example of the chemical reaction which arises in a plasma, (d) -1 and (d) -2 are figures which show an example of the emission spectrum of the plasma to produce | generate.

Explanation of symbols

A Plasma generator / spectroscopy system
A-1 Programmable high frequency power supply
A-2 Pulse bias power supply
A-3 Spectroscopic analysis unit
A-4 Gas supply unit
A-5 PC section (personal computer) section
B Multi-flexible feeder system
B-1 Power supply line
B-1a Grounding sleeve
B-1b Power sleeve
B-1c Insulation sleeve
B-2 Gas supply line
B-2a Gas introduction pipe
B-3 Fiber optical transmission line
B-3a optical fiber conduit
B-4 Pulse bias voltage application line
B-4a Pulse bias voltage application line
C Portable atmospheric pressure plasma generator
C-1 Discharge part
C-2 Photodetector
C-3 outer shell
C-3a Gas flow switch
C-3b Gas excitation switch 1 Laval nozzle 3 Power electrode 3a Axial part 3b Longitudinal part 4 Ground electrode 4a Auxiliary electrode 5 Optical fiber conduit 6 Gas flow arrow 7 Processed object 8 External insulation pipe 9 Internal insulation pipe 10a Programmable high-frequency voltage Interlocking relay for intermittent operation 10b Interlocking relay for intermittent pulse bias voltage 14 Insulation jacket

Claims (4)

A ground electrode arranged on the outer periphery of the outer insulating tube so as to be movable in the axial direction;
An auxiliary electrode having the same potential as that of the ground electrode, disposed at the outer periphery of the outer insulating tube,
An inner insulating pipe disposed along the axis of the outer insulating pipe;
A high-speed nozzle for gas introduction disposed at the rear end of the external insulating tube;
A power electrode arranged in the inner insulating tube and configured to bring a part or the whole into contact with a plasma gas generated by ionizing a gas introduced from the high-speed nozzle; and
A plasma gas outlet opening at the tip of the outer insulating tube;
A gas supply unit that supplies a gas for generating plasma to the high-speed nozzle;
A programmable high-frequency power source that supplies high-frequency power for discharge between the ground electrode and the auxiliary electrode and the power electrode,
The ground electrode can be moved from a position closest to the tip of the power electrode to a position as close to the auxiliary electrode as necessary to avoid the power electrode from becoming hot, and during plasma ignition, A portable atmospheric pressure plasma generator characterized in that a ground electrode is positioned closest to the tip of the power electrode . 2. The portable atmospheric pressure plasma generator according to claim 1, wherein a pulse bias voltage is applied between the power electrode and a workpiece to be processed by a pulse bias power source.   The portable atmospheric pressure plasma generator according to claim 1 or 2, wherein an optical fiber conduit is extended to observe the light emission state in the vicinity of the air outlet at the distal end of the external insulating tube up to the distal end of the external insulating tube.   The optical fiber conduit is connected to a spectroscopic analyzer, and the gas excited state around the outlet is spectroscopically monitored by the spectroscopic analyzer, and the obtained excited state data is compared with the reference excited state data to obtain a desired gas excited state. The portable atmospheric pressure plasma generator according to claim 3, configured to control a high-frequency voltage / current waveform of the programmable high-frequency power source, a gas species mixing ratio supplied by the gas supply unit, and various gas flows so as to be obtained. .

Images