JP7235545B2 - Plasma device - Google Patents

Description

Embodiments of the present invention relate to plasma devices.

In recent years, attention has been focused on techniques for treatment, sterilization, and the like using plasma or chemically active species generated by plasma. For example, chemically active species have an anti-inflammatory effect, and are known to enhance the repairing effect of inflamed tissue. In addition, it is possible to generate plasma at normal temperature and normal pressure, and it is also possible to directly irradiate a living body with plasma or an active gas containing chemically active species.

Japanese Patent No. 6230411

Since it is necessary to apply an extremely high voltage to generate plasma, the effect is also great. For example, electromagnetic waves generated by the flow of high-voltage current may affect surrounding devices. Further, in order to irradiate an irradiation target with plasma or active gas, it is necessary to generate plasma near the irradiation target and irradiate it quickly. Therefore, the plasma generation position cannot be limited to a specific area where safety is ensured. Therefore, it is important to ensure the safety of plasma equipment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma apparatus that is safer than conventional ones.

A plasma apparatus, which is one embodiment of the present invention, includes a plasma generator, a supply, a high voltage line, and a ground line. The plasma generator generates plasma. The supply supplies power to the plasma generator. The high voltage line carries power from the supply to the plasma generator. The ground wire electrically grounds the plasma generator. Also, the ground wire includes a first conductor, a first insulating layer, and a first shield layer. The first conductor is electrically grounded. The first insulating layer is provided so as to cover the outer periphery of the conductor. The first shield layer is conductive and provided so as to cover the outer periphery of the first insulating layer.

Schematic diagram showing an example of a plasma apparatus according to an embodiment of the present invention. The figure which shows typically the structural example inside a plasma generator. FIG. 4 is a diagram schematically showing an internal configuration example of a high-voltage line and a ground line; The figure which shows typically the example of an internal structure near the terminal of a plasma generator. FIG. 4 is a diagram schematically showing an internal configuration example of a connection cable; The figure explaining the bending test with respect to a connection cable. The figure which shows the result of a bending test.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(One embodiment of the present invention)
FIG. 1 is a schematic diagram showing an example of a plasma apparatus according to one embodiment of the present invention. A plasma device 1 according to one embodiment of the present invention includes a plasma generator 11 , a supply device 12 and a connection cable 13 . A high-voltage wire 131 , a ground wire 132 , and a gas supply pipe 133 are accommodated in the connection cable 13 .

The plasma device 1 of this embodiment is a device that generates plasma in atmospheric pressure and irradiates gas containing chemically active species generated by the plasma. Here, gas containing chemically active species is described as atmospheric pressure plasma. A chemically active species is an atom, molecule, ion, etc. in a highly reactive state. Examples of chemically active species include reactive oxygen species and reactive nitrogen species. Examples of active oxygen species include hydroxyl radicals, singlet oxygen, ozone, hydrogen peroxide, superoxide anion radicals, and the like. Examples of active nitrogen species include nitric oxide, nitrogen dioxide, peroxynitrite, peroxynitrite, dinitrogen trioxide, and the like. However, the chemically active species generated by the plasma device 1 of this embodiment are not limited to those illustrated.

Atmospheric pressure plasma has efficacy such as bactericidal and cell activation. Therefore, by irradiating an affected area with atmospheric pressure plasma, it is possible to treat a living body such as a human or an animal. For example, it is known that periodontal disease is improved by using atmospheric pressure plasma. However, the plasma device 1 is not limited to medical applications, and can be used for various applications such as promoting plant growth and sterilizing equipment.

Since the distance that chemically active species can diffuse is extremely short, the atmospheric pressure plasma must be generated and irradiated near the irradiation target of the atmospheric pressure plasma. For example, the distance from the irradiation port of the atmospheric pressure plasma to the irradiation target may be about 5 mm. Therefore, an instrument that generates and irradiates atmospheric pressure plasma must be of a size and weight that can be held by fingers and brought close to the irradiation target. Therefore, a high voltage generation circuit for generating high voltage, gas required for generating atmospheric pressure plasma, etc. cannot be included in the instrument.

Therefore, in this embodiment, the plasma apparatus is divided into separate housings for the plasma generator 11 and the supply device 12 , and the connection cable 13 connects the plasma generator 11 and the supply device 12 . The plasma generator 11 has a size and weight that can be held by fingers and brought close to an irradiation target, and generates and irradiates plasma and atmospheric pressure plasma. Electric power and gas required for generating atmospheric pressure plasma are supplied from a supply device 12 in a housing different from that of the plasma generator 11 via a connection cable 13 . More specifically, the power is supplied via a high voltage line 131 and the gas is supplied via a gas supply pipe 133 . In order to distinguish from atmospheric pressure plasma, the gas is hereinafter referred to as atmospheric pressure plasma generating gas.

The supply device 12 boosts an alternating current from a general power source such as a household power source using a built-in high voltage generation circuit, converts it to a high voltage, and supplies it to the plasma generator 11 . The AC voltage to be supplied is assumed to be approximately 12 to 14 kVpp, but may be determined as appropriate. For example, in order to keep the temperature of generated plasma low, it is preferably 20 kVpp or less. Also, in order to efficiently generate plasma, it is preferably 5 kVpp or less. The unit "Vpp (Volt peak to peak)" representing the AC voltage is the potential difference between the highest value and the lowest value of the AC voltage waveform. A portable power supply may be used instead of a general power supply.

The frequency of the alternating current supplied to the plasma generator 11 is assumed to be approximately 7 kHz, but may be determined appropriately. The frequency is preferably 0.5 kHz or more and less than 20 kHz, more preferably 1 kHz or more and less than 15 kHz, still more preferably 2 kHz or more and less than 10 kHz, particularly preferably 3 kHz or more and less than 9 kHz, and most preferably 4 kHz or more and less than 8 kHz. Each upper limit value is set to keep the temperature of the generated plasma low, and each lower limit value is set for plasma generation efficiency.

The supplier 12 is connected to a container for storing the atmospheric pressure plasma generating gas, and supplies the atmospheric pressure plasma generating gas in the container to the plasma generator 11 at a predetermined supply rate. A flow rate controller such as an automatic control valve may be used to adjust the supply speed. The supply rate of the atmospheric pressure plasma generating gas is assumed to be approximately 3 L per minute (3 L/min), but may be determined appropriately. For example, it is preferably 1 L/min or more in order to suppress the temperature rise of the object to be irradiated. In addition, it is preferably 10 L/min or less for cleaning, activation, or promotion of healing by atmospheric pressure plasma. Depending on the structure of the plasma generator 11, the supply pressure is assumed to be 0.2 to 0.25 MPa. The container may be housed inside the supply device 12 or may be externally attached to the supply device 12 .

The gas for generating atmospheric pressure plasma is not particularly limited as long as it is a gas capable of generating chemically active species. Examples of gases that can be used as the atmospheric pressure plasma generating gas include nitrogen and rare gases. Moreover, these gases may be used individually by 1 type, and may be used in combination of 2 or more types. In addition, it is preferable that the gas for plasma generation contains nitrogen as a main component. Here, "mainly composed of nitrogen" means that the content of nitrogen in the plasma generating gas is more than 50% by volume. That is, the nitrogen content in the plasma generating gas is preferably more than 50% by volume, more preferably 70% by volume or more, and particularly preferably 90% to 100% by volume. Gas components other than nitrogen in the plasma generating gas are not particularly limited, and examples thereof include oxygen and rare gases.

The plasma generator 11 generates atmospheric pressure plasma using the electric power and the atmospheric pressure plasma generating gas thus supplied. Generation of atmospheric pressure plasma in the plasma generator 11 will be described. FIG. 2 is a diagram schematically showing an internal structural example of the plasma generator 11. As shown in FIG. FIG. 2 shows a cross section parallel to the longitudinal direction of the plasma generator 11 . Also, FIG. 2 shows a portion related to the generation of atmospheric pressure plasma, and other portions are omitted. As shown in FIG. 2, the plasma generator 11 includes a tubular dielectric 111, an internal electrode 112, and an external electrode 113. As shown in FIG.

Tubular dielectric 111 is a cylindrical dielectric. Tubular dielectric 111 is installed such that the axial direction of tubular dielectric 111 is substantially parallel to the longitudinal direction of plasma generator 11 . The end of the gas supply pipe 133 exists within or is close to the hollow of the tubular dielectric 111 . The gas supply pipe 133 transfers the atmospheric pressure plasma generation gas from the supplier 12 to the plasma generator 11 . Therefore, the atmospheric pressure plasma generating gas flows from the gas supply pipe 133 into the hollow of the tubular dielectric 111 as indicated by the arrow G in FIG. Also, the atmospheric pressure plasma generating gas flows toward the tip of the plasma generator 11 . Here, the end connected to the connection cable 13 of the plasma generator 11 is defined as the terminal end, and the opposite side is defined as the distal end.

An internal electrode 112 is installed in the hollow of the tubular dielectric 111 so as to be separated from the inner wall of the tubular dielectric 111 . The internal electrode 112 is a conductor and is installed such that the longitudinal direction of the internal electrode 112 is substantially parallel to the axial direction of the tubular dielectric 111 . In the example of FIG. 2, threads are formed on the outer peripheral surface of the internal electrode 112 in order to generate and maintain plasma with low power. However, the shape of the internal electrode 112 is not limited as long as plasma can be generated between it and the external electrode 113 . For example, the internal electrode 112 may be coiled.

A high voltage line 131 is connected to the internal electrode 112 . The high-voltage line 131 is also connected to the supplier 12 and transmits the power V from the supplier 12 to the plasma generator 11 (specifically, the internal electrode 112 within the plasma generator 11).

It is also conceivable to control the start and stop of plasma generation with an operation switch provided on the plasma generator 11 . In that case, the high voltage line 131 is also connected to the operating switch.

An external electrode 113 that is a cylindrical conductor is installed so as to cover the outer periphery of the tubular dielectric 111 . Moreover, as shown in FIG. 2, the external electrode 113 is installed so that a part of the internal electrode 112 exists in the hollow of the external electrode 113 .

Also, the external electrode 113 is connected to one end of the ground wire 132 . The ground wire 132 is in electrical contact with the ground through a metal fitting or the like connected to the other end of the ground wire 132 . That is, the ground wire 132 electrically grounds the plasma generator 11 .

When electric power is supplied to the internal electrode 112, plasma is generated in the plasma generation region 114 inside the tubular dielectric 111 indicated by the dotted frame in FIG. The atmospheric pressure plasma generation gas that has passed through the plasma generation region 114 reacts with the plasma and is ionized to become chemically active species. This creates an atmospheric pressure plasma.

The tip of the plasma generator 11 is opened as an irradiation port, and the irradiation port reaches the tubular dielectric 111 . The end of the tubular dielectric 111 on the tip side of the plasma generator 11 is also opened. Therefore, the atmospheric pressure plasma generated within the tubular dielectric 111 is irradiated to the outside through the irradiation port as indicated by the arrow P in FIG. In addition, as shown in FIG. 2, in order to make it easier to irradiate the irradiation target with the atmospheric pressure plasma, the tip of the plasma generator 11 may be provided with a nozzle that covers the irradiation port.

By applying a high voltage between the internal electrode 112 and the external electrode 113 in this manner, atmospheric pressure plasma is generated. When atmospheric pressure plasma is generated, a high voltage current flows through the high voltage line 131 and electromagnetic waves are generated around the high voltage line 131 . The high-voltage line 131 is accommodated in the connecting cable between the plasma generator 11 and the feeder 12 but exists outside the housings of the plasma generator 11 and the feeder 12 . Therefore, devices around the connection cable 13 including the high-voltage line 131 may be affected by the electromagnetic waves, that is, electromagnetic interference (EMI), which may cause problems such as malfunction. Therefore, it is necessary to prevent electromagnetic waves from leaking from the connection cable 13 .

Also, when atmospheric pressure plasma is generated, a discharge current flows between the internal electrode 112 and the external electrode 113 , and this discharge current causes a protective conductor current to flow through the ground wire 132 . Therefore, electromagnetic waves are generated not only from the high voltage line 131 but also from the ground line 132 . Therefore, it is preferable to take measures against electromagnetic wave leakage not only for the high-voltage line 131 but also for the ground line 132 .

FIG. 3 is a diagram schematically showing an internal configuration example of the high-voltage line 131 and the ground line 132. As shown in FIG. FIG. 3A shows a cross section perpendicular to the longitudinal direction of the high voltage wire 131 . As shown in FIG. 3A, the high voltage line 131 includes a conductor 1311, an insulating layer 1312, and a conductive shield layer 1313. As shown in FIG. A conductor 1311 exists in the center of the high voltage line 131 . An insulating layer 1312 is provided so as to cover the outer circumference of the conductor 1311 . Further, a shield layer 1313 is provided so as to cover the outer circumference of the insulating layer 1312 .

FIG. 3B shows a cross section perpendicular to the longitudinal direction of the ground wire 132 . As shown in FIG. 3B, the ground wire 132 includes a conductor 1321, an insulating layer 1322, and a conductive shield layer 1323. As shown in FIG. A conductor 1321 is present in the center of the ground wire 132 . An insulating layer 1322 is provided so as to cover the outer circumference of the conductor 1321 . Furthermore, a shield layer 1323 is provided so as to cover the outer circumference of the insulating layer 1322 . In the example of FIG. 3, the high-voltage line 131 and the ground line 132 are composed of the same components, although the symbols of the components are changed.

Conductor 1311 of high voltage line 131 transmits power from supply 12 to plasma generator 11 . On the other hand, the conductor 1321 of the ground wire 132 is electrically grounded and passes the protective conductor current. As materials for the conductors 1311 and 1321, materials generally used as conductors of electric wires, such as copper, copper foil threads, copper alloys, copper-clad steel wires, and aluminum, may be used. The structure of the conductor may also be a general structure, and is assumed to be a flexible stranded wire.

Insulating layers 1312 and 1322 are made of insulators and insulate conductors 1311 and 1321 from the outside, respectively. As a material for the insulator, a material used for general electric wire insulators, such as thermosetting resin and thermoplastic resin, may be used. Examples of thermoplastic resins include polyethylene, polypropylene, polyvinyl chloride, polystyrene, and acrylonitrile-butadiene-styrene resin (ABS resin). Examples of thermosetting resins include phenol resins, melamine resins, urea resins, epoxy resins, unsaturated polyester resins, silicone resins, and the like.

Shield layers 1313 and 1323 prevent electromagnetic waves generated by currents flowing through conductors 1311 and 1321 from leaking to the outside. Braided conductors, ie, braided wires, may be used as shield layers 1313 and 1323 . The braided wire is obtained by weaving fibrous conductors into a mesh. The braided wire can form the shield layers 1313 and 1323 without gaps and with sufficient flexibility. Examples of the material for the braid include metal strands, copper foil threads, combinations thereof, and the like. The metal wire is exemplified by a copper wire, a copper alloy wire, or a plated wire. The copper foil thread is obtained by winding copper foil around an insulating thread. Instead of the braided wire, the shield layer may be constructed by winding a conductive wire, a conductive tape, a metal foil, or the like around the insulator.

The shield layers 1313 and 1323 may be composed of multiple layers. For example, it is assumed that the braid material, winding method, etc. are changed in each layer.

In addition, the shield layers 1313 and 1323 can also be electrically grounded and serve to ground the plasma generator 11 . As a result, it is possible to prevent a contact current from flowing to a living body that touches the housing of the plasma generator 11 . Also, when the shield layers 1313 and 1323 are electrically grounded, the shielding effect against electromagnetic waves is enhanced, and leakage of electromagnetic waves can be further prevented.

For example, shield layers 1313 and 1323 are in contact with the housing of plasma generator 11 and the housing of feeder 12 . It is also assumed that the housing of the feeder 12 is electrically grounded by the ground wire of the general power supply used by the feeder 12 . In this case, the plasma generator 11 is electrically grounded together with the feeder 12 . The plasma generator 11 can also be electrically grounded by removing a portion of the insulating layer 1322 of the ground wire 132 and bringing the exposed conductor 1321 into contact with the inside of the housing of the plasma generator 11 . Thus, the shield layers 1313 and 1323 can have not only the function of shielding electromagnetic waves but also the function of electrically grounding the plasma generator 11 and the like.

FIG. 4 is a diagram schematically showing an internal structural example near the end of the plasma generator 11. As shown in FIG. FIG. 4 shows the high voltage line 131 and the ground line 132, and the gas supply pipe 133 is omitted. In the example of FIG. 4, shield layers 1313 and 1323 are formed of braided wires. Assume that the braided wire is electrically grounded. As shown in FIG. 4, a metal foil 1314 is wound around the shield layer 1313 and a metal foil 1324 is wound around the shield layer 1323 . Therefore, the outer diameters of the portions of the high-voltage wire 131 and the ground wire 132 wound with metal foil are larger than the outer diameters of the other portions.

A screw hole 115 sandwiched between the high voltage wire 131 and the ground wire 132 is also shown. The housing of the plasma generator 11 is composed of several parts, and the screw holes 115 are used to fasten the screws that connect the parts together. A high-voltage wire 131 and a ground wire 132 are placed in a gap between the screw hole 115 and the inner wall of the housing. This restricts the movement of the high-voltage wire 131 and the ground wire 132 so that the metal foils 1314 and 1324 physically contact the housing without a fixing member. In this way, the housing of the plasma generator 11 can be electrically grounded.

Also, as in the example of FIG. 4, both shield layers 1313 and 1323 preferably serve as grounds. When the shield layers 1313 and 1323 are braided wires, even if one of the braided wires cannot obtain the effect of grounding due to disconnection or the like, grounding can be ensured through the other braided wire.

The number of times the metal foil is wound may differ between the high-voltage wire 131 and the ground wire 132 . If the number of times is equal for the high voltage wire 131 and the ground wire 132 , the outer diameter of the ground wire 132 remains smaller than the outer diameter of the high voltage wire 131 . Therefore, as shown in FIG. 4, when the gaps between the high-voltage wire 131 and the ground wire 132 are substantially equal, the ground wire 132 is more likely to separate from the housing than the high-voltage wire 131 without the fixing member. Therefore, in the case of the installation location as shown in FIG. 4, it is conceivable to wind the ground wire 132 with more metal foil than the high voltage wire 131 so that the outer diameters of the ground wire 132 and the high voltage wire 131 are approximately equal. As a result, the degree of electrical connection between the ground wire 132 and the housing is substantially equal to the degree of electrical connection between the high-voltage line 131 and the housing. Equalizing the degree of electrical connection in this manner is preferable in terms of ensuring grounding to the housing. By adjusting the number of windings of the metal foil in this way, it is conceivable to adjust the thickness of the metal foil and strengthen the degree of contact between the plasma generator 11 and the housing.

The contact current may be prevented by forming the housing of the plasma generator 11 using an insulating material. The insulating material may be the same as the insulator forming insulating layers 1312 and 1322 .

Note that the high-voltage line 131 and the ground line 132 may have layers other than those described above. For example, layers may be provided outside of shield layers 1313 and 1323 to prevent damage. Moreover, when there are four or more layers, there may be another layer between the shield layer and the insulating layer.

Also, as shown in FIG. 1 , the high voltage line 131 and the ground line 132 are housed in the connection cable 13 at least between the plasma generator 11 and the supply device 12 . The connection cable 13 is assumed to be a hollow cable covered with an insulator, ie a sheath cable. In addition, the sheath cable may have a shield layer that covers the high voltage wire 131 and the ground wire 132 . Since the high-voltage wire 131 and the ground wire 132 are accommodated in the shield layer in the connection cable 13, leakage of electromagnetic waves can be further prevented.

However, as described above, when the number of layers of each of the high-voltage line 131, the ground line 132, and the connection cable 13 increases, the flexibility of the connection cable 13 becomes a problem. The connection cable 13 preferably has flexibility so as not to hinder the movement of the plasma generator 11, but the more layers it has, the less flexibility the connection cable 13 has. Moreover, if the gas supply pipe 133 is also accommodated in the connection cable 13 as shown in FIG. 1, the flexibility is further reduced.

Due to the flexibility of the connection cable 13 , the outer diameter of the ground wire 132 is preferably smaller than the outer diameter of the high voltage wire 131 . The high-voltage wire 131 needs to have a sufficient outer diameter to allow current to flow for plasma generation. , the flexibility of the sheath cable is reduced. Therefore, although it is possible to use the same cable as the high-voltage wire 131 for the ground wire 132, it is possible to use a cable different from the high-voltage wire 131 so that the outer diameter of the ground wire 132 is smaller than the outer diameter of the high-voltage wire 131. preferable. Specifically, the outer diameter of ground wire 132 is preferably less than two-thirds the outer diameter of high-voltage wire 131 . In other words, the outer diameter of high-voltage wire 131 is preferably 1.5 times or more the outer diameter of ground wire 132 . In this way, it is preferable to keep the outer diameter of the connection cable 13 small and secure sufficient space in the connection cable 13 to maintain the flexibility of the connection cable 13 .

From the viewpoint of ease of movement of the plasma generator 11, it is preferable that the cross section perpendicular to the longitudinal direction of the connection cable 13 is circular. Therefore, the outer diameters of the high-voltage wire 131 and the ground wire 132 are preferably adjusted so that the circular shape is maintained. For example, it is conceivable to prevent the circle from being distorted by limiting the outer diameter of the high-voltage wire 131 to three times or less than the outer diameter of the ground wire 132 .

It is conceivable to provide a common shield layer covering the high-voltage line 131 and the ground line 132 instead of providing a shield layer for each of the high-voltage line 131 and the ground line 132, but sufficient flexibility must be ensured. becomes difficult. Also, the high voltage line 131 and the ground line 132 may affect each other. Therefore, as described above, it is preferable to provide shield layers 1313 and 1323 for high voltage line 131 and ground line 132, respectively, and to make the outer diameters of shield layers 1313 and 1323 different as described above.

FIG. 5 is a diagram schematically showing an internal configuration example of the connection cable 13. As shown in FIG. FIG. 5 shows a section perpendicular to the longitudinal direction of the connection cable 13 . A high voltage line 131 , a ground line 132 and a gas supply pipe 133 are contained in the hollow of the connection cable 13 . It is conceivable that the connection cable 13 is made of, for example, polyvinyl chloride resin, polyurethane resin, or the like so as to protect the accommodated cable from external forces.

The material of the gas supply pipe 133 is not particularly limited, and known materials used for the gas supply pipe 133 can be applied. For example, a resin pipe, a rubber tube, or the like can be used as the material of the gas supply pipe 133 . Due to the flexibility of the connection cable 13, it is preferable to use a highly flexible material for the gas supply pipe 133.

In the example of FIG. 5, when the shield layers 1313 and 1323 are braided wires, that is, when the outer diameter of the braided wire of the high-voltage wire 131 is larger than the outer diameter of the braided wire of the ground wire 132, both braided wires It is conceivable that the lifetimes of For example, the degree of damage when the connection cable 13 is bent is considered to vary depending on the outer diameter of the braided wire. Therefore, a bending test was performed on the connection cable 13 to investigate damage to the braided wire due to bending.

FIG. 6 is a diagram explaining a bending test for the connection cable 13. FIG. A bending test is performed using two cylindrical jigs 2 . As shown in FIG. 6, the jig 2 is arranged so that its axial direction is horizontal. The connection cable 13 is passed vertically so as to be sandwiched between the two jigs 2 . In this state, while applying a constant load W to the lower end of the connection cable 13, the upper end of the connection cable 13 is bent so as to contact the upper side of one jig 2, and then contact the upper side of the other jig 2. Bend. Bending in these two directions is alternately repeated.

In this test, a wire with an outer diameter of 5.5 mm and a withstand voltage of 30 kV was used as the high-voltage wire 131 . The diameter of the conductor 1311 of the high voltage line 131 is 4.3 mm, and the thickness of the shield layer 1313 is 0.3 mm. The shield layer 1313 uses a braided wire of 0.10 mm nickel-plated Cu wire. The braid density is 99.9%. An electric wire with an outer diameter of 3.2 mm was used as the ground wire 132 . The conductor 1321 of the ground wire 132 is equivalent to 18 AWG (American wire gauge). The shield layer 1323 of the ground wire 132 is the same as the shield layer 1313 of the high voltage wire 131 . A sheath cable with an outer diameter of 14 mm and an outer layer thickness of 2 mm was used as the connection cable 13 , and a flexible air tube with an outer diameter of 4 mm was used as the gas supply pipe 133 .

FIG. 7 is a diagram showing the results of bending tests. FIG. 7A shows the results for the high voltage line 131. FIG. FIG. 7B shows the results for the ground wire 132. FIG. The horizontal axis in FIG. 7 indicates the number of times of bending, and the vertical axis indicates the resistance value of the braided wire. When an abnormality occurs due to bending, the resistance value begins to vary and gradually increases. Therefore, occurrence of abnormality can be recognized from the resistance value.

As shown in FIG. 7A, there is no variation in the resistance value of the braided wire of the high-voltage wire 131 up to 200,000 bends. On the other hand, the resistance value of the braided wire of the ground wire 132 started to fluctuate and gradually increased after 120,000 times. Therefore, it is considered that a braided wire with a smaller outer diameter is more likely to break.

Thus, the braided wire of the ground wire 132 having a small outer diameter is more likely to break than the braided wire of the high-voltage wire 131 . Therefore, in preparation for breakage of shield layer 1323 of ground wire 132, shield layer 1313 of high-voltage wire 131 should preferably also serve as a ground for the plasma generator, as shown in FIG. In order to prevent failures, it is assumed that the connection cable 13 will be replaced periodically, but it is preferable that the replacement timing be based on the ground wire 132 having a small outer diameter.

As described above, in the plasma device 1 of the present embodiment, not only the high-voltage line 131 but also the ground line 132 has the shield layer 1323, so electromagnetic wave leakage can be prevented more effectively than the existing device. Also, by electrically grounding the shield layers 1313 and 1323 and bringing them into contact with the housing of the plasma generator 11, the plasma generator 11 can be electrically grounded and contact current can be prevented.

In this embodiment, from the viewpoint of the operability of the person who operates the plasma generator 11, the electric power and the atmospheric pressure plasma generating gas are supplied from one supply device 12. FIG. However, there may be a case where power and gas for generating atmospheric pressure plasma are supplied from separate suppliers 12 . Therefore, the high-voltage line 131, the ground line 132, and the gas supply pipe 133 do not necessarily have to be accommodated in one connection cable 13. FIG.

It should be noted that the described embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 Plasma Device 11 Plasma Generator 111 Tubular Dielectric 112 Internal Electrode 113 External Electrode 114 Plasma Generation Region 115 Screw Hole 12 Feeder 13 Connection Cable 131 High Voltage Line 1311 High Voltage Line Conductor 1312 High Voltage Line Insulating Layer 1313 High Voltage Line Shielding Layer 1314 High voltage wire metal foil 132 Earth wire 1321 Earth wire conductor 1322 Earth wire insulation layer 1323 Earth wire shield layer 1324 Earth wire metal foil 133 Gas supply pipe 2 Jig G Plasma generating gas P Atmospheric pressure plasma

Claims (7)

a plasma generator;
a power supply for powering the plasma generator;
a high voltage line that transmits power from the feeder to the plasma generator;
a ground wire that electrically grounds the plasma generator;
a sheath cable housing the high voltage line and the ground line between the plasma generator and the feeder;
with
The ground wire
an electrically grounded first conductor;
a first insulating layer provided to cover the outer periphery of the first conductor;
a conductive first shield layer provided to cover the outer periphery of the first insulating layer;
with
The high voltage line is
a second conductor for transmitting power from the supply to the plasma generator;
a second insulating layer provided to cover the outer periphery of the second conductor;
a conductive second shield layer provided to cover the outer periphery of the second insulating layer;
with
the second shield layer is electrically grounded and in contact with a housing of the plasma generator;
The outer diameter of the second shield layer is larger than the outer diameter of the first shield layer
plasma equipment. 2. The plasma device of claim 1, wherein the first shield layer is a braided conductor. 3. The plasma device of claim 1 or 2, wherein the first shield layer is electrically grounded and in contact with the housing of the plasma generator. 4. The plasma device according to any one of claims 1 to 3, wherein the second shield layer is a braided conductor. 5. The plasma apparatus according to any one of claims 1 to 4, wherein the outer diameter of the second shield layer is 1.5 times or more the outer diameter of the first shield layer. 6. The plasma apparatus according to any one of claims 1 to 5, wherein the sheath cable has a third shield layer covering the ground wire and the high voltage wire. further comprising a gas supply pipe for transmitting gas supplied from the supplier to the plasma generator;
7. The plasma apparatus according to any one of claims 1 to 6 , wherein the gas supply pipe is housed in the sheath cable between the plasma generator and the supplier.

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