Plasma head and plasma generation device

Abstract

This plasma head comprises: a pair of electrodes to which a voltage is applied and which convert a flowing process gas to plasma; a support portion that supports the electrodes; a grounding portion that contacts and grounds an electrode member including the electrodes and / or a member that is electrically connected to the electrodes; and one or more discharge-receiving portions that are provided to the support portion and are formed toward the electrode member.

Description

Plasma head and plasma generator

[0001] Disclosed herein are plasma heads and plasma generating devices.

[0002] A conventional plasma generator has been proposed in which, for example, a dielectric portion is provided on the opposing surfaces of a pair of electrodes, a slit passage that serves as a discharge portion is formed between these dielectric members by the electrodes, both widthwise ends of the dielectric member extend beyond the opposing surfaces of the electrodes, and a spacer is provided between these extended ends (for example, Patent Document 1).In this device, the inner widthwise end face of the slit passage formed by the spacer is positioned widthwise outward of the discharge portion, thereby alleviating electric field concentration at the inner widthwise end face of the slit passage for discharge.

[0003] Japanese Patent Application Laid-Open No. 2006-228658

[0004] In the above-mentioned plasma generator, if there is some abnormality in the grounded portion, for example, an arc may fall on the workpiece. In this plasma generator, the bottom plate facing the workpiece is used as a lightning rod, but if the bottom plate facing the workpiece cannot be disposed near the outlet, plasma processing may not be performed normally.

[0005] The present disclosure has been made in consideration of such problems, and has as its main object to provide a plasma head and a plasma generating device that can more reliably perform plasma processing.

[0006] In this disclosure, the following means are adopted to achieve the above-mentioned main object.

[0007] The plasma head of the present disclosure comprises a pair of electrodes to which a voltage is applied to convert a flowing process gas into plasma, a support portion that supports the electrodes, a grounding portion that contacts and grounds the electrodes and / or electrode members including members electrically connected to the electrodes, and one or more discharge receiving portions that are provided on the support portion and formed toward the electrode members.

[0008] With this plasma head, even when the grounding portion is unavailable, the arc is induced in the discharge receiving portion that is provided on the support portion and formed toward the electrode member, thereby further suppressing erroneous discharges and enabling more reliable plasma processing.

[0009] 1 is a schematic explanatory diagram showing an example of a plasma generation device 10. FIG. 2 is a perspective view and a cross-sectional view of a plasma head 40. FIG. 3 is an explanatory diagram of a rectification unit 50 and a discharge receiving unit 46. FIG. 4 is an explanatory diagram of a cover member 35 and a confirmation unit 36. FIG. 5 is an explanatory diagram of plasma processing when the brushes of the plasma heads 140 and 40 are worn out.

[0010] This embodiment will be described below with reference to the drawings. FIG. 1 is a schematic explanatory diagram showing an example of a plasma generator 10. FIG. 2 is a perspective view and a cross-sectional view of a plasma head 40. FIG. 3 is an explanatory diagram of a rectifier 50 and a discharge receiver 46. FIG. 4 is an explanatory diagram of a cover member 35 and a confirmation unit 36. In this embodiment, the left-right direction (X-axis), front-rear direction (Y-axis), and up-down direction (Z-axis) are assumed to be as shown in FIG. 1 for convenience. Here, the plasma generator 10 will be described as an atmospheric pressure plasma generator, for example.

[0011] The plasma generator 10 is a device that generates plasma under atmospheric pressure. As shown in Fig. 1, the plasma generator 10 includes an arm robot 12, a control device 20, a power supply device 28, a gas supply device 30, and a plasma head 40. The plasma generator 10 supplies power from the power supply device 28 to the plasma head 40 via a power cable, and supplies a process gas to be converted into plasma from the gas supply device 30 via a supply pipe 31. The plasma generator 10 irradiates the workpiece W with plasma gas from the plasma head 40 to perform surface treatment of the workpiece W.

[0012] The arm robot 12 is configured as a moving unit that moves the plasma head 40 to approach and move away from the workpiece W. The arm robot 12 may be configured as, for example, a vertically articulated five-axis robot or a six-axis robot. The arm robot 12 has a mounting unit 13, an arm 14, a drive motor 15, and a base 16. The mounting unit 13 is a portion to which the plasma head 40 can be attached and detached, and is disposed at the tip of the arm 14. The arm 14 is made up of multiple members pivotally supported by joint shafts and freely rotates around the joint shafts to move the plasma head 40 in three-dimensional space in the front-to-back, left-to-right, and up-to-down directions. The drive motor 15 is disposed on each joint shaft and drives the joint shafts to rotate. The base 16 supports and installs the arm 14. Note that, although the arm robot 12 is used as the moving unit here, an XY robot capable of moving the plasma head 40 in the up-to-down direction may also be used, provided that the plasma head 40 can be freely moved.

[0013] The control device 20 controls each device of the plasma generation device 10. The control device 20 includes a control unit 21, a memory unit 22, a communication unit 23, a display unit 24, and an operation unit 25. The control unit 21 is configured as a microprocessor centered on a CPU and controls the entire plasma generation device 10. The control unit 21 outputs control signals to the arm robot 12, power supply unit 28, gas supply unit 30, plasma head 40, etc. The memory unit 22 is a large-capacity storage medium such as a flash memory, and stores programs for controlling the plasma generation device 10 and job information including the shape of the workpiece W and the surface treatment position. The communication unit 23 is an interface for exchanging information with external devices such as a management server (not shown). The display unit 24 is a display that displays information to the operator. The operation unit 25 is used by the operator to input various information and includes various buttons, levers, etc. In the plasma generating device 10, the arm robot 12, power supply device 28, gas supply device 30, and plasma head 40 are described as being controlled by a single control device 20, but a control unit may be provided for each device, or each control process may be shared among multiple control units.

[0014] The power supply device 28 is a device that supplies power to the external electrode 41 and the internal electrode 42. The power supply device 28 generates high-frequency AC power from, for example, a commercial power source to be supplied to the pair of external electrode 41 and internal electrode 42 of the plasma head 40. The power supply device 28 supplies the generated AC power to the external electrode 41 and internal electrode 42 of the plasma head 40.

[0015] The gas supply device 30 supplies a process gas to the outer electrode 41 and the inner electrode 42 of the plasma head 40. The gas supply device 30 may be configured to supply a process gas containing at least one of an inert gas such as nitrogen and an active gas such as oxygen, for example, air, by pressure delivery. The gas supply device 30 includes a supply pipe 31, a supply valve 32, and a gas supply tank (not shown). The supply pipe 31 is a pipe connected between the supply tank of the gas supply device 30 and the plasma head 40. The supply valve 32 controls the supply and stop of the process gas. The gas supply device 30 may also include a heater for heating the process gas supplied to the plasma head 40, if necessary.

[0016] The plasma head 40 irradiates a workpiece W supported on a work table with plasma gas to modify the surface of the workpiece W. Examples of surface modification include a modification process that changes the surface from hydrophobic to hydrophilic. The plasma head 40 is removably attached to the mounting unit 13 of the arm robot 12. The base end of the plasma head 40 is attached to the mounting unit 13, and the tip end is covered by a cover member 35. A nozzle 47 that irradiates the plasma gas generated by the plasma head 40 is provided below the cover member 35. The plasma head 40 includes an external electrode 41, an internal electrode 42, a drive unit 43, a support unit 44, the nozzle 47, and a grounding unit 50.

[0017] The external electrode 41 is a member having a nozzle 47 formed therein and through which the process gas flows. The external electrode 41 is electrically grounded via a brush 51 serving as a grounding member of the grounding section 50. As shown in FIGS. 2 and 3 , the external electrode 41 is fixed to a holder 41 a. The holder 41 a is a cylindrical member disposed at the tip end of the main body 48 and through which the process gas flows. Note that the holder 46 is electrically connected to the external electrode 41, and therefore the holder 46 can also be considered part of the external electrode 41. The internal electrode 42 is housed inside the holder 41 a connected to the external electrode 41 and is an electrode that converts the process gas into plasma between the holder 41 and the external electrode 41. The internal electrode 42 is fixed to a holder 42 s and electrically connected to a power cable connected to the power supply 28. A voltage is applied to the process gas using power supplied from the power supply 28. The holder 42 a is connected to the power supply 28, is tapered toward the tip end, and is a member into which the internal electrode 42 can be inserted. Since the holder 42a is electrically connected to the internal electrode 42, the holder 42a can also be considered to be part of the internal electrode 42. A rectifying member 55 is disposed above the internal electrode 42. The rectifying member 55 is a member that converts the process gas into a spiral flow and circulates it between the external electrode 41 and the internal electrode 42 when converting the process gas into plasma. The plasma head 40 converts the process gas into plasma by applying a voltage to the process gas supplied between the external electrode 41 and the internal electrode 42, thereby generating plasma gas. The plasma head 40 includes components electrically connected to the external electrode 41 and the internal electrode 42, and for ease of explanation, these will be collectively referred to as "electrode members." The nozzle 47 is a tip member formed with an outlet for discharging the plasma gas. The nozzle 47 is disposed at the lower end of the plasma head 40 so as to face the workpiece W. An inner inclined surface 52 that is inclined toward the second member 57 is formed at the upstream end of the inner member 51 in the process gas flow direction. In the plasma head 40, a voltage is applied to the process gas supplied between the outer electrode 41 and the inner electrode 42, thereby converting the process gas into plasma and generating a plasma gas.

[0018] The drive unit 43 is a motor that rotates a main body 48 at the tip side of the plasma head 40. The plasma head 40 irradiates the workpiece W with plasma gas while rotating the main body 48. The main body 48 is provided with an external electrode 41, an internal electrode 42, a nozzle 47, and the like.

[0019] The support 44 is a member that supports the main body 48 of the plasma head 40 so that it can rotate about its axis. The support 44 is removably attached to the attachment part 13. In addition to supporting the main body 48, the support 44 also supports the supply pipe 31 connected to the gas supply device 30 and the power cable connected to the power supply device 28. The support 44 rotatably supports the main body 48 via a fixing member 45 disposed below the support 44. The fixing member 45 is a box-shaped member having walls and houses the upper side of the main body 48. The fixing member 45 is a conductive member to which a conductive cable (not shown) is connected and electrically grounded. As shown in FIGS. 2 and 3 , the fixing member 45 fixes the grounding portion 50 to the electrode member on a fixing surface extending perpendicular to the rotation axis of the main body 48 so that the grounding portion 50 can contact the electrode member. The fixing member 45 has an opening 49 formed therein that can house the main body 48, including the external electrode 41 and the internal electrode 42, without contacting the electrode member. The grounding portion 50 is fixed near the opening edge 49 a of the opening 49 .

[0020] As shown in FIG. 3 , the fixing member 45 is provided with a discharge receiving portion 46. The discharge receiving portion 46 is an effective portion for grounding the external electrode 41 when the grounding portion 50 for grounding the external electrode 41 does not function. The discharge receiving portion 46 is provided on the fixing member 45 of the support portion 44 and is formed facing the electrode member. This discharge receiving portion 46 is a conductive member that does not contact the electrode member and is grounded via the fixing member 45. The discharge receiving portion 46 is provided on the fixing member 45 on which the grounding portion 50 is disposed and which is electrically grounded. This discharge receiving portion 46 is formed on the fixing member 45 of the support portion 44 as a portion that protrudes toward the electrode member that rotates about its axis. The discharge receiving portion 46 may be a separate member disposed on the fixing member 45, or may be an integrally molded member in which a portion of the fixing member 45 is processed into a protruding shape. The discharge receiving portion 46 may be formed so that a portion of the fixing member 45 that is electrically grounded by the grounding portion 50 and faces the electrode member protrudes toward the electrode member. Alternatively, the discharge receiving portion 46 may be formed so as to protrude toward the electrode member at an opening edge 49 a of the fixing member 45. Only one discharge receiving portion 46 may be provided on the support portion 44 at a position facing the electrode member, or multiple discharge receiving portions 46 may be provided. Here, for example, one or more discharge receiving portions 46 may be provided, but one discharge receiving portion 46 may be provided on the front side of the plasma head 40, or multiple discharge receiving portions 46 may be provided at three positions between the three fixed positions of the grounding portion 50.

[0021] The grounding portion 50 contacts the external electrode 41 and / or an electrode member including a member electrically connected to the external electrode 41, thereby grounding the external electrode 41. The grounding portion 50 contacts the axially rotating main body 48 to electrically ground it. As shown in FIGS. 1 to 3 , the grounding portion 50 includes a brush 51 and a brush fixing portion 52. The brush 51 is a contact member that contacts the electrode member electrically connected to the external electrode 41. The brush 51 is formed of a conductive material such as carbon and is a consumable item that wears down with use. The brush 51 is replaced by an operator as it wears out. The brush fixing portion 52 is a member that fixes the brush 51 so that it can contact the electrode member. Since the electrode member rotates in the plasma head 40, the grounding portion 50 is fixed to three locations on the opening edge 49 a to further improve contact during rotation. The brush fixing portion 52 incorporates a biasing portion, such as a spring, that biases the brush 51 toward the electrode member. The external electrode 41 is grounded via a conductive brush 51, a brush fixing portion 52, a fixing member 45, a conductive cable, and the like.

[0022] The cover member 35 is a member that covers the electrode member of the plasma head 40. As shown in FIGS. 1 and 4 , the cover member 35 has a wall portion 36 that covers the electrode member and a confirmation portion 37 formed on the wall portion 36 so that the discharge receiving portion 46 can be visually confirmed. By covering the electrode member, the wall portion 36 protects the electrode member and increases the safety of the operator and surrounding area. The confirmation portion 37 may be an opening that allows the interior to be visually confirmed, or may be a window portion with a transparent window member fitted into the opening. One or more confirmation portions 37 may be provided depending on the location of the discharge receiving portion 46. When one discharge receiving portion 46 is provided on the front side of the plasma head 40, one confirmation portion 37 is provided at a position where the discharge receiving portion 46 can be confirmed. Furthermore, when multiple discharge receiving portions 46 are provided, multiple confirmation portions 37 may be provided depending on the locations of the discharge receiving portions 46. From this confirmation unit 37, the worker can check the status of the discharge receiving unit 46 and its surroundings, such as whether an arc discharge is occurring at the discharge receiving unit 46. Note that if one discharge receiving unit 46 and one confirmation unit 37 are provided, this is preferable because it makes it easier for the worker to check for an arc discharge.

[0023] Next, a surface modification process of the workpiece W using the plasma generator 10 configured as described above will be described. When a command to start the surface modification process is input from the operation unit 25, the control unit 21 first outputs a command signal to the gas supply device 30 to supply a process gas to the plasma head 40. Next, the control unit 21 moves the plasma head 40 using the arm robot 12 to a position facing the workpiece W, and rotates the main body 48 using the drive unit 43. Next, the control unit 21 applies a voltage between the external electrode 41 and the internal electrode 42 to convert the process gas into plasma, which is then irradiated onto the workpiece W.

[0024] FIG. 5 is an explanatory diagram of plasma processing when the brush of the plasma head 140, 40 is worn. FIG. 5A is an explanatory diagram of plasma processing using a conventional plasma head 140 without a discharge receiving portion 46, and FIG. 5B is an explanatory diagram of plasma processing using a plasma head 40 with a discharge receiving portion 46. When plasma processing is performed, the external electrode 41 of the plasma head 40 is grounded by the brush 51, but the brush 51 wears with use. The control device 20 of the plasma generator 10 may count the usage time of the brush 51 and determine when it is time to replace the brush 51. When the brush 51 needs to be replaced, the control device 20 can display a message or alarm on the display unit 24 to prompt the operator to replace the brush 51. However, this message or alarm can be reset using the operation unit 25, and it is difficult for the control device 20 to determine whether the brush 51 has actually been replaced. If the plasma head 40 is used without replacing the brush 51, a situation may occur in which the grounding portion 50 is not grounded. For example, as shown in Figure 5A, in a plasma head 140 without a discharge receiving portion 46, if the grounding portion 50 does not function and there is no return route for the high voltage, an erroneous discharge to nearby metal may occur. On the other hand, in a plasma head 40 in which the discharge receiving portion 46 is provided near the electrode member of the external electrode 41, the arc is guided to the discharge receiving portion 46, so a safe current loop can be formed via the discharge receiving portion 46. Furthermore, since the discharge receiving portion 46 is visible from the confirmation portion 37, the operator can visually check it and be prompted to replace the brush 51.

[0025] Here, the correspondence between the components of this embodiment and the components of the present disclosure will be clarified. The external electrode 41 and the internal electrode 42 of this embodiment are an example of a pair of electrodes of the present disclosure, the support portion 44 and the fixing member 45 are an example of a support portion and a fixing member, the ground portion 50 is an example of a ground portion, and the discharge receiving portion 46 is an example of a discharge receiving portion.

[0026] The plasma generator 10 of the present embodiment described above has a plasma head 40 including a pair of electrodes that generate plasma from a flowing process gas when a voltage is applied, a support portion 44 that supports the electrodes, a grounding portion 50 that contacts and grounds the electrodes and / or electrode members including members electrically connected to the electrodes, and one or more discharge receiving portions 46 that are provided on the support portion 44 and formed toward the electrode members. With this plasma head 40, even when the grounding portion 50 is unavailable, an arc is induced to the discharge receiving portion 46 that is provided on the support portion 44 and formed toward the electrode members, thereby further suppressing erroneous discharges and enabling more reliable plasma processing.

[0027] The plasma head 40 also includes a drive unit 43 that drives a main body 48, including an electrode member, to rotate about an axis. The support unit 44 supports the main body 48 for rotation about the axis. The grounding unit 50 contacts the axially rotating electrode member. The discharge receiving unit 46 is formed on the support unit 44 facing the axially rotating electrode member. This plasma head 40, which has an axially rotating electrode member, can perform plasma processing more reliably. Furthermore, this plasma head 40 can more easily provide the discharge receiving unit 46 because it only needs to be disposed on the outer periphery of the electrode member. The discharge receiving unit 46 may be a grounded conductive member that does not contact the electrode member. Furthermore, the discharge receiving unit 46 is provided on a fixed member 45 that is electrically grounded and has a grounding unit 50 disposed thereon. In this plasma head, the discharge receiving unit 46 can be easily grounded, further simplifying its structure and configuration. Furthermore, the discharge receiving portion 46 is provided with a grounding portion 50 for electrical grounding, and is formed by a part of the fixing member 45 that faces the electrode member and protrudes toward the electrode member without contacting it. In this plasma head 40, part of the fixing member 45 serves as the discharge receiving portion 46, which further simplifies the structure.

[0028] In the plasma head 40, the support portion 44 includes a fixing member 45 that fixes the grounding portion 50 so that it can contact the electrode member. The fixing member 45 has an opening that can accommodate the electrode therein, and the discharge receiving portion 46 is formed at the edge 49a of the opening of the fixing member 45, protruding toward the electrode member. In this plasma head 40, the discharge receiving portion 46 is formed at the edge 49a of the opening of the fixing member 45, further simplifying the structure. Furthermore, the plasma head 40 includes a cover member 35 that has a wall portion 36 that covers the electrode member and a confirmation portion 37 formed on the wall portion 36 so that the discharge receiving portion 46 can be visually confirmed. In this plasma head 40, the state of the grounding portion 50 can be indirectly confirmed by checking the state of the discharge receiving portion 46 using the confirmation portion 37. Furthermore, since only one discharge receiving portion 46 is provided on the support portion 44, it is easy to arrange the confirmation portion 37 and it is also easy for the operator to check whether or not an arc discharge is occurring at the discharge receiving portion 46. This allows the operator to recognize the wear state of the brush 51 of the grounding portion 50. The pair of electrodes in the plasma head 40 includes an external electrode 41 that is electrically grounded by the grounding portion 50 and through which the process gas flows, and an internal electrode 42 that is housed inside a holder 41a serving as an external electrode member to which the external electrode 41 is connected and to which a voltage is applied, thereby converting the process gas into plasma between the external electrode 41 and the internal electrode 42. In this plasma head 40, erroneous arc discharge between the electrodes having the external electrode 41 and the internal electrode 42 is further suppressed, thereby enabling more reliable plasma processing.

[0029] The plasma generator 10 also includes the above-described plasma head 40, a power supply device 28 that supplies power to the electrodes, and a gas supply device 30 that supplies a process gas to the electrodes. Because the plasma generator 10 includes the above-described plasma head, it is possible to further suppress erroneous arc discharge and more reliably perform plasma processing.

[0030] It goes without saying that the plasma head and plasma generation device of the present disclosure are not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure.

[0031] For example, in the above-described embodiment, the main body 48 is rotationally driven, but this is not particularly limited, and the main body 48 including the electrodes may not rotate. Even in such a plasma head 40, the presence of the discharge receiving portion 46 can further suppress erroneous discharges and more reliably perform plasma processing.

[0032] In the above-described embodiment, the discharge receiving portion 46 is provided on the conductive fixing member 45 on which the grounding portion 50 is disposed, but this is not particularly limited, and the discharge receiving portion 46 may be provided on a member different from the member on which the grounding portion 50 is disposed. Furthermore, the discharge receiving portion 46 may be provided on a non-conductive member.

[0033] In the above-described embodiment, the discharge receiving portion 46 is provided on the opening edge 49a of the fixing member 45, but the location where it is provided is not particularly limited thereto, and it may be provided on the grounding portion 50, such as the brush fixing portion 52. In this case, it is preferable because it makes it easier to ground the discharge receiving portion 46. Furthermore, the discharge receiving portion 46 may be a separate member attached to the fixing member 45, or may be integrated with the fixing member 45.

[0034] In the above-described embodiment, the cover member 35 is provided with the confirmation portion 37 for the opening, but this is not particularly limited, and the confirmation portion 37 may be omitted. Also, while the cover member 35 is provided on the plasma head 40, this is not particularly limited, and the cover member 35 may be omitted.

[0035] In the above-described embodiment, the present disclosure has been described as the plasma generating device 10, but is not particularly limited to this, and may be a plasma head 40 or a discharge receiving portion 46.

[0036] This specification also discloses the technical idea of ​​changing "the plasma head according to claim 1 or 2" to "the plasma head according to any one of claims 1 to 3" in claim 4 as originally filed, the technical idea of ​​changing "the plasma head according to claim 1 or 2" to "the plasma head according to any one of claims 1 to 4" in claim 5 as originally filed, the technical idea of ​​changing "the plasma head according to claim 1 or 2" to "the plasma head according to any one of claims 1 to 5" in claim 6 as originally filed, the technical idea of ​​changing "the plasma head according to claim 1 or 2" to "the plasma head according to any one of claims 1 to 6" in claim 7 as originally filed, and the technical idea of ​​changing "the plasma head according to claim 1 or 2" to "the plasma head according to any one of claims 1 to 7" in claim 8 as originally filed.

[0037] The present disclosure is applicable to the technical field of processing the surface of a workpiece.

[0038] 10 Plasma generator, 12 Arm robot, 13 Mounting section, 14 Arm, 15 Drive motor, 16 Base section, 20 Control device, 21 Control section, 22 Memory section, 23 Communication section, 24 Display section, 25 Operation section, 28 Power supply device, 30 Gas supply device, 31 Supply pipe, 32 Supply valve, 35 Cover member, 36 Wall section, 37 Confirmation section, 40, 140 Plasma head, 41 External electrode, 41a Holder, 42 Internal electrode, 42a Holder, 43 Drive section, 44 Support section, 45 Fixing member, 46 Discharge receiving section, 47 Nozzle, 48 Main body, 49 Opening, 49a Opening edge, 50 Grounding section, 51 Brush, 52 Brush fixing section, W Work.

Claims

1. A pair of electrodes that are applied with a voltage and plasmaize the flowing process gas, a support portion that supports the electrodes, a ground portion that contacts and grounds an electrode member including the electrodes and / or members electrically connected to the electrodes, and one or more discharge receiving portions provided in the support portion and formed toward the electrode member. A plasma head comprising the same.

2. The plasma head according to claim 1, further comprising a drive portion that rotationally drives the electrodes about an axis, wherein the support portion supports the electrodes so as to be rotatable about the axis, the ground portion contacts the axially rotating electrode member, and the discharge receiving portion is formed in the support portion toward the axially rotating electrode member. A plasma head.

3. The plasma head according to claim 1 or 2, wherein the discharge receiving portion is provided in a fixed member where the ground portion is disposed and electrically grounded.

4. The plasma head according to claim 1 or 2, wherein the discharge receiving portion is formed such that a part of a fixed member where the ground portion is disposed and electrically grounded and that faces the electrode member protrudes toward the electrode member side.

5. The plasma head according to claim 1 or 2, wherein one discharge receiving portion is provided in the support portion.

6. The plasma head according to claim 1 or 2, further comprising a cover member having a wall portion that covers the electrode member and a confirmation portion in which the discharge receiving portion is visibly formed in the wall portion.

7. The plasma head according to claim 1 or 2, wherein the electrodes include a cylindrical external electrode that is electrically grounded by the ground portion and through which the process gas flows, and an internal electrode that is housed inside the external electrode, to which a voltage is applied, and that plasmaizes the process gas between the external electrode.

8. A plasma generating device comprising the plasma head according to claim 1 or 2, a power supply device that supplies power to the electrodes, and a gas supply device that supplies the process gas to the electrodes.

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