Excimer lamp

Abstract

The invention provides an excimer lamp. The purpose of the present invention is to efficiently irradiate an ultraviolet irradiation object with ultraviolet light in an excimer lamp. An excimer lamp of an ultraviolet irradiation device is provided with a discharge vessel (520) and a processing vessel (530), an expanded diameter portion (561) is provided to a dielectric (560) of the discharge vessel (520), and a large diameter portion (523) is provided to a discharge tube (521) of the discharge vessel (520). The processing container (530) is welded to the expanded-diameter section (561) and the large-diameter portion (523), and a flow path (R) is formed around the discharge container (520), the flow path (R) being a fluid that is an object to be irradiated with ultraviolet light.

Description

TECHNICAL FIELD

[0001] The present application relates to an excimer lamp. BACKGROUND

[0002] In an excimer lamp, it is possible to emit light by discharging by applying a high-frequency voltage between electrodes, and to irradiate ultraviolet rays radiated from a discharge vessel to a processing object or the like. Also, it is possible to generate ozone by irradiating ultraviolet rays to a raw material gas for ozone generation.

[0003] In an ultraviolet irradiation device, an ozone generation device, it is required to effectively irradiate ultraviolet rays to a flow path in which a raw material gas or the like flows. For example, there is known an ultraviolet irradiation device in which an ultraviolet irradiation space is provided around a light emitting tube (see Patent Document 1). Here, the light emitting tube and an outer tube are arranged in a concentric circular shape, and between them, an ultraviolet irradiation object such as water is supplied to a processing space and discharged.

[0004] Also, there is known an ozone generation device in which an excimer lamp of a double tube structure is arranged in a cylindrical housing, and a flow path for a raw material gas to flow is formed (see Patent Document 2). Here, the excimer lamp is inserted through the outer tube to provide a flow path tube for ozone generation and a flow path tube for a cooling medium to flow.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-138014

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2016-37416

[0007] In the case of an excimer lamp, it is necessary to configure a flow path tube or the like that surrounds the light emitting tube in accordance with the size thereof, and it is difficult to form a flow path along the surface of the lamp while maintaining a distance interval that does not attenuate ultraviolet rays. SUMMARY

[0008] Therefore, in an excimer lamp, it is required to effectively irradiate ultraviolet rays to an ultraviolet irradiation object.

[0009] The excimer lamp of the present application can be applied to an ultraviolet irradiation device, which has an electrode and a tubular discharge vessel that forms a discharge space around the electrode. Also, the structure of the electrode (inner electrode) is various. It is not limited to a structure that employs a foil electrode covered with a dielectric, and it is possible to employ an inner electrode that is rod-shaped or plate-shaped or the like. Also, it is possible to employ a structure in which the inner electrode is exposed to the discharge space.

[0010] The excimer lamp of the present application has a tubular discharge vessel that forms a discharge space, and an outer vessel that forms a flow path between the discharge vessel, and the end portion of the flow path in at least one of the lamp axial directions is formed at a position that is closer to the center of the lamp axial direction than the end portion of the discharge vessel.

[0011] For example, at least one end portion of the flow path in the lamp axial direction can be formed at a position closer to the central side in the lamp axial direction than the end portion of the cylindrical portion of the discharge vessel. The gap distance of the flow path in the lamp axial direction can be constant in the cylindrical portion of the discharge vessel.

[0012] The gap distance of the flow path in the lamp radial direction can be smaller than the thickness of the outer vessel. For example, the gap distance of the flow path in the lamp radial direction can be set to a range of 0.2 mm or more and 2 mm or less.

[0013] For example, an excimer lamp having a pair of electrodes provided inside the discharge vessel and outside the outer vessel can be constructed. At least one end portion of the flow path can be formed at a position closer to the end portion in the lamp axial direction than a range in which the pair of electrodes face each other.

[0014] For example, an excimer lamp having an inner electrode provided inside the discharge vessel can be constructed. At least one end portion of the flow path can be formed at a position closer to the end portion in the lamp axial direction than the end portion of the inner electrode.

[0015] The other end portion of the flow path can be formed to the end portion side in the lamp axial direction beyond the end portion of the cylindrical portion of the discharge vessel. Also, the length of the flow path in the lamp axial direction can be longer than the length of the cylindrical portion in the lamp axial direction.

[0016] Another aspect of the excimer lamp of the present application further has a vessel (here, referred to as an outer vessel) that covers the discharge vessel and forms a flow path between the discharge vessel. For example, the outer vessel is provided with a flow inlet and a flow outlet (flow path pipe), and a fluid such as a gas or a liquid flows in the flow path.

[0017] The excimer lamp can irradiate ultraviolet rays to a fluid flowing in the flow path, or can irradiate ultraviolet rays to an ultraviolet ray irradiation target object housed in the lamp. The outer vessel has various forms, and for example, a cylindrical portion that surrounds a discharge space of the discharge vessel can be formed in a circular cross section. Also, the outer vessel can be disposed coaxially with the discharge vessel. Here, the flow path is formed throughout the entire range of the circumferential direction of the discharge vessel with respect to the discharge space.

[0018] In the present application, the outer vessel is integrated with the discharge vessel by being fused to the discharge vessel. For example, the outer vessel made of a glass material such as quartz glass can be integrated with the discharge vessel by being fused. The outer vessel can be fused in a manner of surrounding the discharge vessel.

[0019] Another aspect of the excimer lamp of the present application forms a flow path around a discharge space, and has both a function as an ultraviolet ray irradiation lamp and a function as a processing vessel for an ultraviolet ray target object. Such an excimer lamp is effective for an ultraviolet ray irradiation device or the like that radiates ultraviolet rays of a peak wavelength that attenuates greatly when passing through a fluid.

[0020] As for the fusion portion of the discharge vessel and the outer vessel, various fusions can be performed. For example, the outer vessel is fused to the discharge vessel in the vicinity of the end portion of the discharge vessel along the lamp axis in a manner deviated from the discharge region. Alternatively, the outer vessel can be fused to the discharge vessel in the vicinity of the flow path tube (flow inlet, flow outlet, etc.) connected to the flow path.

[0021] For example, the outer vessel can be fused to the discharge vessel in a manner that the distance interval (width) of the flow path is substantially constant in the cylindrical portion surrounding the discharge space of the discharge vessel, and the direction and cross-sectional area of the flow path flow are changed in the vicinity of the end portion of the discharge vessel.

[0022] The outer vessel can be fused to the portion of the discharge vessel that protrudes more than other portions. As the protruding portion, for example, a flange-like portion can be formed in the discharge vessel.

[0023] The discharge vessel has various forms, and an extension portion extending from one end portion can be provided. For example, the extension portion can be configured to cover a portion of the dielectric of the electrode. In this case, the flange-like portion can be provided to the extension portion.

[0024] Further, the outer vessel can be configured to be fused to the end portion of the discharge vessel. Alternatively, the outer vessel can be fused to the end portion of the discharge vessel or an exhaust pipe formed in the vicinity of the end portion.

[0025] A structure in which the outer vessel is covered with a reflective film that reflects ultraviolet rays can also be employed. For example, a reflective film that reflects ultraviolet rays radiated from the discharge space can be provided to cover the discharge vessel over a range including the central portion of the lamp up to the lamp end portion side along the tube axis beyond the fusion portion of the outer vessel and the discharge vessel. The reflective film can cover the outer surface of the flow path tube provided to the outer vessel and connected to the flow path.

[0026] The structure of the outer electrode opposite to the above-described electrode is various. The outer electrode can be provided to the outer surface side of the processing vessel. For example, the above-described reflective film can be configured as the outer electrode. Further, an electrode configuration in which a wire-like electrode is wound around the outer surface of the outer vessel can also be employed.

[0027] According to the present application, in an excimer lamp, ultraviolet rays can be effectively irradiated to an ultraviolet ray irradiation target. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a cross-sectional view of the excimer lamp of the ultraviolet ray irradiation apparatus of the first embodiment along the lamp axis.

[0029] Figure 2 is a cross-sectional view along Figure 1 II-II line of the excimer lamp of the ultraviolet ray irradiation apparatus of the first embodiment.

[0030] Figure 3is a cross-sectional view of an excimer lamp of the first modification example.

[0031] Figure 4 is a cross-sectional view of an excimer lamp of the second modification example.

[0032] Figure 5 is a cross-sectional view of an excimer lamp of the ultraviolet irradiation device of the second embodiment.

[0033] Figure 6 is a cross-sectional view of an excimer lamp of the ultraviolet irradiation device of the third embodiment.

[0034] Figure 7 is a cross-sectional view of an excimer lamp of the third modification example of the first embodiment.

[0035] Explanation of Reference Numerals

[0036] 1: ultraviolet irradiation device; 10: excimer lamp; 20: discharge vessel; 21: discharge tube; 23: large-diameter portion; 30: treatment vessel; 40: electrode (inner electrode); 50: reflective film (outer electrode); 60: dielectric; 61: enlarged-diameter portion; 63: flange-like portion; 500: ultraviolet irradiation device; 510: excimer lamp; 520: discharge vessel; 521: discharge tube; 523: large-diameter portion; 530: treatment vessel; 540: electrode (inner electrode); 550: reflective film (outer electrode); 560: dielectric; 561: enlarged-diameter portion; 563: flange-like portion. DETAILED DESCRIPTION

[0037] Hereinafter, an ultraviolet irradiation device having an excimer lamp of the present embodiment will be described with reference to the drawings.

[0038] Figure 1 is a cross-sectional view of an excimer lamp of the ultraviolet irradiation device of the first embodiment along a lamp axis. Figure 2 is a cross-sectional view along Figure 1 II-II line.

[0039] The ultraviolet irradiation device 500 has an excimer lamp 510 and a power supply section (not shown), and a power supply wire 70 is connected to the power supply section. The excimer lamp 510 is configured as an ultraviolet irradiation lamp in which a tubular discharge vessel 520 and a treatment vessel (outer vessel) 530 are integrated. Here, a gas such as air or a liquid such as water is supplied to the ultraviolet irradiation device 500 as an ultraviolet irradiation target.

[0040] The discharge vessel 520 is configured of a dielectric material such as quartz glass, and an electrode 40 is disposed inside the discharge vessel 520 along a tube axis (hereinafter, referred to as a lamp axis C). The electrode 40 is configured as a foil electrode extending along the lamp axis C, and an end portion 40T1 of the electrode 40 on one side in the direction of the lamp axis C is connected to the power supply rod (power supply wire) 70.

[0041] The electrode 40 is covered with a dielectric 560 made of quartz glass or the like so as to be buried without being exposed to the discharge space S. The dielectric 560 has a tapered portion (hereinafter, referred to as an enlarged diameter portion) 561 that extends along the lamp axis C and that is enlarged in diameter from the vicinity of the end portion 40T1 of the electrode 40.

[0042] The discharge vessel 520 has a portion (hereinafter, referred to as a discharge tube) 521 that is a bottomed cylinder, and is fused at the end portion 521T1 to the enlarged diameter portion 561. In the discharge space S formed between the discharge tube 521 and the dielectric 560, a rare gas such as xenon gas, or a mixed gas of a rare gas and a halogen gas is enclosed as a discharge gas.

[0043] The discharge tube 521 is formed into a bottomed cylinder with the discharge tube end portion (hereinafter, also referred to as a front end face) 521T3 as a bottom. The discharge tube 521 has a cylindrical portion (hereinafter, referred to as a cylindrical portion) 521K whose diameter is constant along the lamp axis C, and has a shoulder portion 521R2 whose diameter is reduced from the end portion 521T2 of the cylindrical portion 521K toward the front end face 521T3. The front end face 521T3 of the discharge tube 521 is formed with a protruding portion (hereinafter, referred to as an exhaust pipe) 522 that protrudes along the lamp axis C. The front end 560T2 of the dielectric 560 reaches an inner space of the exhaust pipe 522.

[0044] The shoulder portion 521R2 is formed with a protruding portion (hereinafter, referred to as a large diameter portion) 523 whose thickness and outer diameter are larger than those of other portions and that protrudes in the radial direction than the inner surface of the treatment vessel 530. The outer diameter D5 of the large diameter portion 523 is larger than the inner diameter D4 of the treatment vessel 530 and is smaller than the outer diameter D6 of the treatment vessel 530.

[0045] The dielectric 560 has a protruding portion (hereinafter, referred to as an extension portion) 562 that extends from the enlarged diameter portion 561 to a position outside the discharge tube range L3. The extension portion 562 extends along the lamp axis C and covers the power supply wire 70. Here, the interval L3 along the lamp axis C from the shoulder portion 521R2 of the discharge tube 521 to the enlarged diameter portion 561 of the dielectric 560 is referred to as a discharge tube range. Also, here, the interval L2 in which the cylindrical portion 521 is formed is referred to as a cylindrical range.

[0046] The treatment vessel 530 that is a tube is also made of a dielectric such as quartz glass as with the discharge vessel 520. One end portion 530T1 of the treatment vessel 530 is fused to the enlarged diameter portion 561 of the dielectric 560, and the other end portion 530T2 is fused to the large diameter portion 523. The end portions 530T1, 530T2 of the treatment vessel 530 become end portions RT1, RT2 of the flow path R, respectively.

[0047] The discharge vessel 520 and the processing vessel 530 are covered with a reflective film 50 that reflects ultraviolet rays. Here, the reflective film 50 is configured as an electrode (outer electrode) provided outside the processing vessel 530 in pair with an electrode 40 (hereinafter, referred to as inner electrode) provided inside the discharge vessel 520. The reflective film 50 is configured of, for example, a thin metal film such as an aluminum film.

[0048] As shown in FIG. 1, the reflective film 50 covers the discharge vessel 520 and the processing vessel 530 over a range from a front end of the exhaust pipe 522 of the front end face 521T3 that is exposed without being covered by the processing vessel 530 to a central portion of the lamp, further to the extension portion 562 that exceeds the enlarged diameter portion 561 on the lamp end portion side. Figure 1

[0049] The pair of electrodes configured of the inner electrode 40 and the reflective film 50 as the outer electrode are disposed in opposition along the lamp radial direction within a range along the lamp axis (hereinafter, referred to as electrode opposing range) LI. The outer diameter D2 of the extension portion 562 is larger than the outer diameter Dl of a portion (hereinafter, referred to as small diameter portion) 565 that covers the inner electrode 40.

[0050] An end portion RT2 of one side of the flow path R, that is, an end portion 530T2 of one side of the processing vessel 530 is located along the lamp axis C at a position closer to the central side of the lamp axis than the front end face 521T3 of the discharge pipe 521, that is, within the discharge pipe range L3. Also, the end portion RT2 of one side of the flow path R is located at a position closer to the end portion side of the lamp axis than the electrode opposing range LI.

[0051] An end portion RTl of the other side of the flow path R, that is, an end portion 530Tl of the other side of the processing vessel 530 is located along the lamp axis C at a position closer to the central side of the lamp axis than the enlarged diameter portion 561 of the discharge vessel 520, that is, within the discharge pipe range L3. An interval (hereinafter, referred to as flow path length) L4 from the end portion RTl to the end portion RT2 of the flow path R is longer than the electrode opposing range LI and shorter than the discharge pipe range L3.

[0052] The processing vessel 530 has a flow inlet 531 and a flow outlet 532. The fluid flows in from the flow inlet (flow path pipe) 531 via a pipe not shown, flows in the direction from the end portion RTl to the end portion RT2, and flows out from the flow outlet (flow path pipe) 532. Note that the flow inlet 531 and the flow outlet 532 are not limited to a structure in which they are opened in the same direction in the circumferential direction, and for example, a structure in which they are opened in different directions in the circumferential direction, such as a structure in which they are opened toward opposite sides in the radial direction, can be employed.

[0053] ​The inlet 531 of the processing container 530 is formed near the end RT1 of the flow path R, and is radially opposite to the expanded diameter portion 561 of the discharge capacitor 520. The inlet 531 may also be configured to be radially opposite to the end 40T1 of the inner electrode 40.

[0054] The outlet 532 of the processing container 530 is formed near the end RT2 of the flow path R on the lamp center side, which is larger than the large diameter portion 523, and is radially opposite to the end 40T2 of the inner electrode 40. The outlet 532 may also be configured to be radially opposite to the dielectric 560 (front end 560T2) on the lamp front side, which is larger than the end 40T1 of the inner electrode 40.

[0055] The light emitted from the discharge space S is transmitted to the inlet 531 and the outlet 532. By placing a light sensor near the inlet 531 or the outlet 532, or by visual inspection, the light emitted from the inlet 531 or the outlet 532 to the outside of the lamp can be detected, and the lamp-on status of the excimer lamp 510 can be confirmed.

[0056] Alternatively, the direction of fluid flow can be changed to flow from outlet 532 to inlet 531. In this case, the fluid that flows in from outlet 532 and is exposed to ultraviolet light flows out from inlet 531.

[0057] The flow rate (flow rate) of a fluid flowing in flow path R can be measured using various methods. For example, the flow rate can be adjusted based on the intensity of ultraviolet radiation, or the fluid can be made to flow intermittently (stop flowing) so that the fluid receiving ultraviolet radiation is temporarily stopped within the cylindrical region R2 (flow path R).

[0058] like Figure 2 As shown, the inner electrode 40, dielectric 560, and discharge capacitor 520 (discharge tube 521) are coaxially arranged, and the processing container 530 is coaxially arranged with the discharge capacitor 520. The flow path R of the excimer lamp 510 is formed such that the gap distance G2 of its cylindrical region R2 is constant along the lamp axis C.

[0059] Here, the polarities of the inner electrode 40 and the reflective film 50, which serves as the outer electrode, are set as anode and cathode, respectively. The inner electrode 40 and the reflective film 50, which serve as the outer electrode, are positioned radially opposite each other within the electrode opposition range L1. Furthermore, a high-frequency (e.g., in the range of several kHz to tens of MHz) and high-voltage (e.g., in the range of several kV to tens of kV) power supply is provided to the excimer lamp 510 via the power supply rod 70, applying a high-frequency, high-electric field to the discharge space S and the cylindrical region R2. As a result, a dielectric barrier discharge is generated in the discharge region of the discharge space S, and excimer light of a specified spectrum (e.g., wavelength of 172 nm) is emitted from the discharge space S and irradiates the cylindrical region R2 (flow path R).

[0060] As described above, the inner electrode 40 is a foil electrode, which is an electrode formed to be very thin in thickness relative to width, has a flat portion of constant thickness and wedge-shaped portions that are sharpened from both ends of the width direction of the flat portion to both ends of the width direction of the foil electrode, and both ends of the width direction of the foil electrode are sharpened to the extent of being edge-like in a cross section indicated by a point.

[0061] The dielectric 560 (small diameter portion 565) has a cross-sectional shape that matches the configuration and shape of the foil electrode, and reduces the difference in distance (distance from the thickness of the foil electrode) from any surface of the foil electrode to the outer surface of the dielectric 560.

[0062] Specifically, the cross section of the dielectric 560 in the radial direction of the lamp is set to be long elliptical or long circular. In other words, the cross section of the dielectric 560 is elliptical. The dielectric 560 is substantially the same cross-sectional shape along the tube axis (lamp axis) C throughout the range in which the foil electrode is covered.

[0063] In this way, the dielectric 560 of the cross-sectional long elliptical or cross-sectional long circular shape covers the inner electrode 40 as the foil electrode in a state of being coaxially arranged with the inner electrode 40 as the foil electrode, and the dielectric 560 is coaxially arranged with the discharge vessel 520. Therefore, the electric field strength does not become excessively large in the vicinity of both ends of the inner electrode 40, and it is possible to prevent deviation of the discharge along the circumferential direction of the lamp.

[0064] On the other hand, since both ends of the inner electrode 40 are sharpened (wedge-shaped), it is possible to easily utilize electric field concentration even when there is a cylindrical region R2 around the discharge space S, and to perform start-up by applying a relatively low voltage. In this way, since the outer electrode is not arranged within the cylindrical region R2 (outer surface 520S of the discharge vessel 520), there is no concern that impurities contained in the outer electrode will mix into the fluid.

[0065] In addition, the structure of the inner electrode 40 is various. It is not limited to the structure described above that employs a foil electrode covered by the dielectric 560, and it is also possible to employ an inner electrode that is rod-shaped or plate-shaped or the like. Furthermore, it is also possible to employ a structure in which the inner electrode is exposed to the discharge space.

[0066] In the excimer lamp 510 of the present embodiment, for example, the axial length (light emitting length) of the discharge vessel 520 can be set to a range of 20 mm to 400 mm. Furthermore, the outer diameter of the discharge vessel 520 (discharge tube 521) can be set to a range of 6 mm to 30 mm, and preferably to a range of 8 mm to 25 mm.

[0067] The wall thickness of the discharge vessel 521 can be set to a range of 0.7 mm to 2 mm, for example, in consideration of preventing deterioration of the discharge vessel caused by excimer light and suppressing an increase in the discharge start voltage. Also, the inner diameter of the discharge vessel 521 can be set to a range of 4 mm to 28 mm, and preferably to a range of 5 mm to 23 mm, for example, in consideration of suppressing discharge instability caused by a long discharge distance and insufficient illuminance caused by a short discharge distance.

[0068] The distance interval between the outer surface of the dielectric 560 and the inner surface of the discharge vessel 521, i.e., the discharge distance, can be set to a range of 1 mm to 13 mm, and preferably to a range of 2 mm to 12 mm, for example, in consideration of preventing insufficient illuminance caused by narrow regionalization of the discharge space, preventing destabilization of the discharge caused by expansion of the discharge distance, and the like.

[0069] The shape and size of the treatment container 530 are set in accordance with the ultraviolet intensity, the flow characteristics (flow rate, flow volume, pressure) of the fluid that is the object of ultraviolet irradiation, the size of the discharge vessel 520, such as the outer diameter D3 of the discharge vessel 521, the outer diameter D6 of the treatment container 530, and the like.

[0070] The thickness T1 of the discharge vessel 520 (discharge vessel 521) is set to a range of 0.7 mm to 2 mm, for example. The thickness T2 of the treatment container 530 is set to a range of 0.5 mm to 3 mm. The gap distance of the cylindrical region R2 of the flow path R, i.e., the distance interval G2 between the outer surface of the cylindrical portion 521K of the discharge vessel 520 and the inner surface of the treatment container 530, is set to be equal to or less than the thickness T2 of the treatment container 530. Here, the distance interval G2 is set to a range of 0.2 mm to 6 mm. It can be set to a range of 0.2 mm to 2 mm, respectively, for example.

[0071] As described above, the excimer lamp 510 of the present embodiment is configured such that the discharge vessel 520 and the treatment container 530 are fused, and the flow path R as the treatment space is formed in the cylindrical portion 521K of the discharge vessel 521 around the discharge vessel 520. Since it is a lamp configuration in which the discharge space S is formed around the inner electrode 40, the flow path R becomes a space that is annular (cylindrical) along the outer surface of the discharge vessel 520 (discharge vessel 521), and it is possible to efficiently irradiate the ultraviolet light radiated from the discharge space S to the entire circumferential range of the discharge vessel 521 to the fluid.

[0072] Furthermore, not only the ultraviolet rays radiated from the discharge vessel 520, but also the ultraviolet rays are transmitted inside the tube wall of the dielectric 560, the discharge tube 521, and further to the inside of the tube wall of the processing vessel 530 by multiple reflection. By such an effect of transmitting the ultraviolet rays like an optical fiber, the ultraviolet rays can be irradiated to the fluid from four directions of the flow path R. In particular, the discharge vessel 520 and the processing vessel 530 are each made of the same raw material such as quartz glass, and are integrated with the enlarged diameter portion 561 of the discharge vessel 520 and the large diameter portion 523 by fusion, so that the ultraviolet rays are easily transmitted to the inside of the tube wall of the processing vessel 530.

[0073] Furthermore, by covering the discharge vessel 520 and the processing vessel 530 with the reflecting film 50, the ultraviolet rays can be irradiated to the fluid from the reflecting film 50 side. Also, the reflecting film 50 functions as an outer electrode in close contact with the discharge vessel 520, so that the light emission efficiency of the discharge space S and the reflection efficiency of the reflecting film 50 can be improved.

[0074] Since the processing vessel 530 is fused with the enlarged diameter portion 561 and the large diameter portion 523 located near both end portions of the discharge vessel 520, the discharge vessel 520 and the processing vessel 530 can be coaxially arranged with high precision. In particular, when the gap distance G2 of the cylindrical region R2 of the flow path R is smaller than the thickness Tl of the discharge vessel 520 (the discharge tube 521) and also smaller than the thickness T2 of the processing vessel 530, the discharge vessel 520 and the processing vessel 530 can be coaxially arranged with high precision.

[0075] Thus, the gap distance of the flow path R, that is, the distance between the outer surface of the cylindrical portion 521K of the discharge vessel 520 and the inner surface of the processing vessel 530, G2 (mm), is uniform in the circumferential direction in the cylindrical region R2 surrounding the cylindrical portion 521K. Also, since the enlarged diameter portion 561 is thicker than the extension portion 562 and the large diameter portion 523 is thicker than the other portions of the discharge tube 521, the lamp breakage from the fusion portion as a starting point due to a sharp pressure change caused by the flow rate adjustment of the fluid or the like can be prevented.

[0076] In particular, the outer surface of the large diameter portion 523 whose outer diameter is formed smaller than the outer diameter of the processing vessel 530 is formed in a curved surface shape so that the radial thickness continuously changes in the axial direction, and the outer surface of the fusion portion of the large diameter portion 523 and the end portion 530T2 is formed in a curved surface shape so that the outer peripheral surface of the processing vessel 530 and the outer peripheral surface of the discharge vessel 520 are continuously connected.

[0077] Thus, not only can the mechanical strength of the vicinity of the end portion of the flow path be increased by making the welded portion thick-walled to prevent the lamp from breaking, but also the formation of a minute wedge-shaped gap as a starting point of the lamp breaking on the outer surface of the welded portion can be suppressed, and the outer surface of the welded portion is covered by the reflective film (outer electrode) without a gap. The outer surface of the welded portion of the enlarged diameter portion 561 and the end portion 530T1 can also be formed in a curved shape.

[0078] Such an excimer lamp 510 can be manufactured, for example, by the following manufacturing method.

[0079] First, a convex portion (large diameter portion) having an outer diameter larger than the inner diameter of the insertion port of the processing container is formed on both end portions of the discharge vessel. Then, the exhaust pipe is welded to the opening (exhaust port) of one of the end portions of the discharge vessel.

[0080] Then, the dielectric formed with the sealing portion covering the electrode and the enlarged diameter portion is inserted into the opening (insertion port) of the other end portion of the discharge vessel. At this time, the dielectric is inserted so that the front end thereof reaches the inner space of the exhaust pipe.

[0081] After the dielectric is inserted, the opening (insertion port) of the other end portion of the discharge vessel is welded to the enlarged diameter portion, thereby forming the discharge container. In addition, the diameter of the enlarged diameter portion of the dielectric can be made larger than the inner diameter of the insertion port of the processing container.

[0082] Next, the discharge container is inserted into the tubular processing container having the flow inlet and the flow outlet formed near both ends and being open at both ends from the opening portion (insertion port) of one end. At this time, the large diameter portion of the discharge container is brought into abutment (fit) with the opening portion.

[0083] The large diameter portion of the discharge container becomes a support structure that supports the opening portion (end portion) of the processing container, thereby coaxially arranging (temporarily fixing) the processing container and the discharge container. In addition, the processing container can also be temporarily fixed by the enlarged diameter portion. Then, the end portion (opening portion) of the processing container is welded to the large diameter portion and the enlarged diameter portion of the discharge container.

[0084] Thus, before the discharge container and the processing container are welded, the large diameter portion (or the enlarged diameter portion) of the discharge container supports the end portion of the processing container, thereby enabling the discharge container and the processing container to be coaxially arranged with high precision and then welded.

[0085] Further, the large diameter portion (enlarged diameter portion) functions as a support member for the sealing portion of the flow path, thereby eliminating the need to arrange a support member in the flow path, and thus the ultraviolet rays radiated from the outer surface of the discharge container are not blocked by the support member. Further, there is no concern that abnormal discharge (creeping discharge) along the support member will occur in the flow path in which high frequency and high voltage are applied by the pair of electrodes.

[0086] Further, regarding the protruding portion, instead of the large-diameter portion (or the enlarged diameter portion) of the discharge tube in which the outer diameter of the protruding portion is larger than that of the other portions as described above, a structure in which the protruding portion protrudes in a part of the circumference can be adopted. For example, a structure in which a semispherical or cylindrical protrusion is provided in a part of the circumference of the discharge tube, and the end portion (the opening portion) of the outer vessel before welding is supported coaxially by abutting against the protrusion, and then is welded to be integrated can be adopted.

[0087] Impurities are removed by vacuuming through the exhaust pipe, and then the discharge gas is sealed. Thereafter, the exhaust pipe is sealed by heating and deforming. The outer electrode (the reflective film) is provided on the outer surface over a range from the front end of the sealed exhaust pipe to the central portion of the lamp, and further to the lamp end portion side beyond the welded portion of the outer vessel and the discharge vessel along the pipe axis. By sufficiently removing impurities after the discharge vessel and the processing vessel are welded and before the discharge gas is sealed, a desired lamp performance can be obtained.

[0088] Regarding the flow path formed by welding the discharge vessel 520 and the processing vessel 530, a structure in which the protruding portion is provided in the extension portion and the shoulder portion of the discharge vessel is not limited, and welding as shown below can be performed.

[0089] Figure 3 is a cross-sectional view of the excimer lamp of the first modified example.

[0090] The ultraviolet irradiation device 1 has an excimer lamp 10 and a power supply portion (not shown), and a power supply line 70 is connected to the power supply portion. The excimer lamp 10 is configured as an ultraviolet irradiation lamp in which a tubular discharge vessel 20 and a processing vessel (an outer vessel) 30 are integrated.

[0091] A non-sealed portion 60P that is not sealed with the electrode 40 is provided between the front end 40T2 of the electrode 40 and the front end 60T2 of the dielectric 60. An auxiliary discharge space P for point-light starting is formed inside the non-sealed portion 60P. The auxiliary discharge space P is in a reduced pressure state lower than the atmospheric pressure. Further, a rare gas that reduces the voltage at the time of point-light starting can be sealed in the auxiliary discharge space P at a pressure lower than the atmospheric pressure.

[0092] The discharge tube 21 of the discharge vessel 20 is welded at the end portion 21T1 thereof to the enlarged diameter portion 61 of the dielectric. The discharge tube 21 is in a bottomed cylindrical structure in which a shoulder portion 21R2 is provided between a front end face 21T3 serving as a bottom portion and a cylindrical portion 21K having a constant diameter along the lamp axis C. Further, a protruding portion (an exhaust pipe) 22 that protrudes along the lamp axis C is formed at the end portion 21T3 of the discharge tube 21.

[0093] The extension 62 of the dielectric 60 has a flange-like portion 63 that protrudes in the radial direction and has a thickness and an outer diameter that are larger than those of other portions. The end portion 30T1 of the treatment container 30 on one side is fused to the flange-like portion 63 to form an end portion RT1 of the flow path R.

[0094] A large-diameter portion 23 that protrudes in the radial direction and has a thickness and an outer diameter that are larger than those of other portions is formed in the vicinity of the end portion 21T2 of the cylindrical portion 21K of the discharge tube 21. The outer diameter D5 of the large-diameter portion 23 is larger than the inner diameter D4 of the treatment container 30 and smaller than the outer diameter D6 of the treatment container 30.

[0095] The discharge vessel 20 and the treatment container 30 are covered with a reflective film 50 that reflects ultraviolet rays. The reflective film 50 covers the discharge vessel 20 and the treatment container 30 up to a portion (exposed portion) 64 that is not covered by the treatment container 30 and from which the extension 62 is exposed. The outer diameter D2 of the extension 62 including the exposed portion 64 is larger than the outer diameter D1 of a portion (small-diameter portion) 65 that covers the inner electrode 40.

[0096] An end portion RT2 of the flow path R on the side of the exhaust pipe 22 is formed at a position that is closer to the center of the lamp axis than the front end surface 21T3 of the discharge vessel 20, that is, within the discharge tube range L3. Here, the end portion RT2 is formed at a position that is closer to the center of the lamp axis than the end portion 21T2 of the cylindrical portion 21K of the discharge vessel 20, that is, within the cylinder range L2, and at a position that is outside the electrode-opposing range LI and closer to the end portion side of the lamp axis than the end portion 40T2 of the inner electrode 40.

[0097] An end portion RT1 of the flow path R on the side of the exposed portion 64 is formed at a position that is closer to the end portion side of the lamp axis than the enlarged-diameter portion 61 of the discharge vessel 20, that is, outside the discharge tube range L3. An interval (hereinafter referred to as flow path length) L4 from the end portion RT2 to the end portion RT1 of the flow path R is longer than the discharge tube range L3.

[0098] The flow inlet 31 of the treatment container 30 is formed in the vicinity of the end portion RT1 of the flow path R. The end portion RT1 is located at a position that is closer to the end portion side of the lamp than the cylindrical portion 21K of the discharge tube 21 (outside the cylinder range L2) and at a position that is closer to the exposed portion 64 side than the enlarged-diameter portion 61 of the discharge vessel 20 (outside the discharge tube range L3) along the lamp axis C. Further, the end portion RT1 is opposite a space region (hereinafter referred to as enlarged region) R1. The enlarged region R1 is located between the enlarged-diameter portion 61 and the flange-like portion 63 and has a larger cross-sectional area of the flow path than other portions.

[0099] The gap distance along the radial direction of the enlarged region Rl, that is, the distance between the outer surface of the extension 62 and the inner surface of the processing vessel 30, G1, is longer than the gap distance of the cylindrical space region (cylindrical region) R2 surrounding the cylindrical portion 21K, that is, the distance between the outer surface of the cylindrical portion 21K and the inner surface of the processing vessel 30, G2.

[0100] The flow outlet 32 of the processing vessel 30 is formed near the end portion RT2 of the flow path R on the central side of the large diameter portion 23, and opposes the auxiliary discharge space P (non-sealed portion 60P) along the radial direction of the lamp.

[0101] Such an excimer lamp 10 can be manufactured by the same manufacturing method as the above-described manufacturing method, except for the structure in which the end portion (opening portion) of the processing vessel is fused to the flange-like portion.

[0102] Figure 4 is a cross-sectional view of an excimer lamp of a second modification.

[0103] The excimer lamp 100 has a discharge vessel 120 and a processing vessel 130. The outer diameter D5 of the flange-like portion 163 of the extension 162 of the discharge vessel 120 (dielectric 160) is larger than the outer diameter of the cylindrical portion 121K of the discharge tube 121 and the inner diameter of the processing vessel 130, and is preferably smaller than the outer diameter of the processing vessel 130.

[0104] The processing vessel 130 is fused to the flange-like portion 163 at one end portion (insertion opening) 130Tl and is fused to the exhaust pipe 122, which is a protruding portion of the discharge vessel 120 (discharge tube 121), at the other end portion 130T2. By the fusion, the end portions RTl, RT2 of the flow path R are formed.

[0105] As with the first modification of the first embodiment, the flange-like portion of the discharge vessel supports the end portion of the processing vessel before the discharge vessel is fused to the processing vessel, so that the discharge vessel and the processing vessel can be coaxially arranged with high precision and then fused.

[0106] An enlarged region Rl is formed near the flow inlet 131 of the flow path R. Also, in the second modification, an enlarged region R3 is formed at a position on the front end side of the exhaust pipe 122 from the cylindrical portion 121K along the lamp axis and near the flow outlet 132 of the flow path R.

[0107] An enlarged region R3 is formed between the outer peripheral surface of the exhaust pipe 122, the end portion 121T3 of the discharge pipe 121 and the shoulder portion 121R2 of the outer surface, and the inner surface of the end portion 130T2 of the processing vessel 130. The gap distance in the radial direction of the enlarged region R3, that is, the distance interval between the outer surface of the exhaust pipe 122 and the inner surface of the processing vessel 130 (hereinafter, also referred to as the gap distance) G3 is longer than the distance interval G1 of the enlarged region R1, the distance interval G2 of the cylindrical region R2.

[0108] Thus, a lamp configuration is provided in which the outer surface of the discharge vessel 120 surrounded by the cylindrical region R2 is closer to the inner surface of the processing vessel 130 than the outer surface of the discharge vessel 120 surrounded by the enlarged region R1. Also, the enlarged region R3 having the flow outlet 132 is formed on the exhaust pipe 122 side beyond the discharge pipe range L3, and the flow path length L4 of the flow path R is longer than the discharge pipe range L3 (cylindrical range L2) on both end portion sides along the lamp axis C. The ultraviolet rays radiated from the discharge space S are irradiated to the fluid flowing in the flow path R formed longer along the lamp axis C.

[0109] It can also be configured such that the end portion 130T2 of the processing vessel 130 is fused to the shoulder portion 121R2 formed between the end portion 121T3 of the exhaust pipe side of the discharge pipe 121 and the end portion 121T2 of the cylindrical portion 121K. In this case, the shoulder portion 121R2 is integrated with the large diameter portion 163, and thus the outer diameter of the shoulder portion 21R2 of the discharge pipe 121 is formed larger than other portions.

[0110] Next, the ultraviolet irradiation device of the 2nd embodiment will be described using Figure 5 The ultraviolet irradiation device of the 2nd embodiment will be described. In the 2nd embodiment, the fused portion of the discharge vessel and the processing vessel is provided to the discharge pipe.

[0111] Figure 5 is a cross-sectional view of the excimer lamp of the ultraviolet irradiation device of the 2nd embodiment.

[0112] The excimer lamp 300 has a tubular discharge vessel 320, a processing vessel 330, and the end portion 321T1 of the discharge pipe 321 constituting the discharge vessel 320 is fused to the enlarged diameter portion 361 of the dielectric 360 as in the 1st embodiment. On the other hand, in the cylindrical portion 321K of the discharge pipe 321, a large diameter portion 323 having a thickness and an outer diameter larger than other portions and protruding in the radial direction than the inner surface of the processing vessel 330 is provided at a position on the lamp central (front end surface 321T3) side than the end portion 321T1.

[0113] The outer diameter D5 of the large diameter portion 323 is formed to be larger than the inner diameter of the treatment vessel 330, here, smaller than the outer diameter of the treatment vessel 330. The one end portion 330T1 of the treatment vessel 330 is fused to the large diameter portion 323 to form the end portion RT1 of the flow path R. Also, the other end portion 330T2 is fused to the cylindrical outer peripheral surface of the exhaust pipe 322 of the discharge vessel 320 projecting along the lamp axis C to form the end portion RT2 of the flow path R.

[0114] The flow inlet 331 of the treatment vessel 330 is formed at a position on the lamp central side of the large diameter portion 323 of the discharge vessel 320 and radially opposite to the end portion 40T1 of the inner side electrode 40. Also, the flow outlet 332 of the treatment vessel 330 is located at a position on the front end side of the exhaust pipe 322 than the cylindrical range L2. The flow path length L4 of the flow path R is longer than the cylindrical range L2.

[0115] The outer diameter of the large diameter portion 323 of the discharge vessel 320 is larger than the outer diameter of the cylindrical portion 321K of the discharge pipe 321 and the inner diameter of the treatment vessel 330, here, smaller than the outer diameter of the treatment vessel 330. The end portion 330T1 of the treatment vessel 330 is fused to the large diameter portion 323, whereby the end portion of the treatment vessel can be supported by the large diameter portion of the discharge vessel before the discharge vessel and the treatment vessel are fused, whereby the discharge vessel and the treatment vessel can be coaxially arranged with high precision and then fused.

[0116] On the other hand, since the flow inlet 331 is formed at a position opposite to the inner side electrode 40, the fluid in the vicinity of the flow inlet 331 is also irradiated with ultraviolet rays, and ultraviolet rays can be irradiated over the entire range from the flow inlet 331 to the flow outlet 332 of the flow path R.

[0117] It can also be configured such that not only the end portion 321T1 of the discharge pipe 321 is fused to the enlarged diameter portion 361 of the dielectric 360, but also the large diameter portion 323 of the discharge pipe 321 is fused to the enlarged diameter portion 361. In this case, the enlarged diameter portion 361 is formed in one body with the large diameter portion 323, and the outer diameter of the end portion 321T1 of the discharge pipe 321 is formed to be larger than the other portions.

[0118] The end portion 330T2 of the treatment vessel 330 can also be configured to be fused to the large diameter portion provided to the shoulder portion 321R2 of the discharge pipe 321 as in the first embodiment. Or it can also be configured to be fused to the large diameter portion provided to the front end surface side of the cylindrical portion of the discharge pipe 321 as in the first modification of the first embodiment.

[0119] Such an excimer lamp 300 can be manufactured, for example, by the following manufacturing method.

[0120] First, for a discharge tube of which one end is to be fused with an exhaust pipe and which is formed with a large diameter portion at both ends, a large diameter portion is formed which has an outer diameter larger than the inner diameter of the insertion port of the treatment container. Then, the exhaust pipe is fused with the one open end (exhaust port) of the discharge tube.

[0121] Next, a discharge tube is inserted into the treatment container of which both ends are open with a flow inlet and a flow outlet formed at both end sides, from the one open end (insertion port), and the large diameter portion of the discharge tube is butted against (fitted into) the open end.

[0122] The large diameter portion of the discharge tube becomes a support structure that supports the open end (end) of the treatment container, whereby the treatment container and the discharge tube are coaxially arranged (temporarily fixed). Then, the one end (open end) of the treatment container is fused with the large diameter portion of the discharge tube, and the other end is fused with the outer peripheral surface of the exhaust pipe.

[0123] A dielectric formed with a diameter expanding portion and covering an electrode is inserted into the discharge tube so that a part of the front end of the dielectric reaches the internal space of the exhaust pipe. After the insertion, the end of the discharge tube is fused with the diameter expanding portion of the dielectric. After the fusion, impurities are removed by vacuuming through the exhaust pipe. Then, after the discharge gas is enclosed, the exhaust pipe is sealed by heating and deforming. An outer electrode (reflective film) is provided on the outer surface over a range from the front end of the sealed exhaust pipe, including the central portion of the lamp, to a part of the exposed portion of the flange-like portion along the pipe axis.

[0124] Thus, after the discharge tube is fused with the treatment container to form a flow path, the discharge tube is fused with the dielectric to form a discharge space, whereby when the treatment container is fused, the mixing of impurities into the discharge tube can be suppressed, and the desired lamp performance is obtained.

[0125] Next, a Figure 6 A third embodiment of the excimer lamp will be described. In the third embodiment, the discharge tube extends beyond the diameter expanding portion of the dielectric, and a large diameter portion is provided at the extended portion.

[0126] Figure 6 is a cross-sectional view of the excimer lamp of the third embodiment.

[0127] The excimer lamp 400 has a discharge vessel 420, a treatment container 430, and a discharge tube 421 constituting the discharge vessel 420 is formed with an extended portion 424 that extends along the lamp axis C beyond the diameter expanding portion 461 of the dielectric 460. Further, a large diameter portion 423 having a thickness and an outer diameter larger than those of other portions and protruding in the radial direction beyond the inner surface of the treatment container 430 is provided at a part of the extended portion 424 of the discharge tube 421.

[0128] One end portion 430T1 of the treatment container 430 is fused to the large diameter portion 423 of the discharge tube 421 to form an end portion RT1 of the flow path R, and the other end portion 430T2 is fused to the exhaust pipe 422 of the discharge tube 421 as a protruding portion protruding along the lamp axis C to form an end portion RT2 of the flow path R.

[0129] The flow inlet 431 of the treatment container 430 is formed at a position on the lamp center side of the large diameter portion 423 of the discharge container 420 and opposite the diameter expansion portion 461. Also, the flow outlet 432 of the treatment container 430 is located at a position on the front end side of the exhaust pipe 422 from the end portion 40T2 of the inner electrode 40. The flow path length L4 of the flow path R is longer than the discharge tube length L3.

[0130] By providing the large diameter portion 423 at the extension portion 424 of the discharge container 420, the treatment container 430 is formed in a shape extending beyond the diameter expansion portion 461 of the discharge container 420 to the extension portion 462, the flow path length L4 of the flow path R along the lamp axis C is increased, and is longer than the discharge tube length L3 (cylindrical length L2) on both end portions of the lamp along the lamp axis C. Light radiated from the discharge space S is transmitted through the diameter expansion portion 461 and the extension portion 424 to be radiated to the fluid.

[0131] Also, the reflective film 50 covers the discharge container 420 and the treatment container 430 over a range from the front end of the exhaust pipe 422 of the discharge container 420 to the lamp center portion and further to the portion of the extension portion 424 beyond the large diameter portion 423, and on the other hand, the end portion 424T of the extension portion 424 is not covered by the reflective film 50. By exposing the end portion 424T of the extension portion 424, abnormal discharge caused by surface discharge and insulation breakdown via the extension portion 462 of the dielectric 460 between the reflective film 50 and the power supply rod 70 can be suppressed.

[0132] In addition, with respect to the extension portion 424, instead of being formed as a portion of the discharge tube 421 as described above, a structure can be adopted in which the extension portion is prepared as another member and is fused to the discharge tube 421. For example, the discharge tube can use synthetic quartz glass having a high ultraviolet transmittance, and the extension portion can use fused quartz which is relatively low in price. Also, in order to increase the ultraviolet transmittance, the discharge tube can use thin quartz glass, and the extension portion can use a glass tube having a thickness.

[0133] Further, in addition to the fusion of the end portion 421T1 of the discharge tube 421 and the enlarged diameter portion 461 of the dielectric 460, the large diameter portion 423 can be fused with the enlarged diameter portion 461 of the dielectric 460. In this case, the thickness of the end portion 421T1 of the discharge tube 421 is formed to be thicker than the other portions. As for the end portion 430T2 of the process container 430, it can be configured to be fused with the large diameter portion provided to the shoulder portion 421R2 of the discharge tube 421, as in the first embodiment. Or it can be configured to be fused with the large diameter portion provided to the front end surface side of the cylindrical portion of the discharge tube 421, as in the first modification of the first embodiment.

[0134] Such an excimer lamp 400 can be manufactured, for example, by the following manufacturing method.

[0135] First, a large diameter portion having an outer diameter larger than the inner diameter of the insertion port of the process container is formed to the discharge tube which is open at both ends. The exhaust pipe is inserted into the dielectric covering the electrode from the opening (exhaust port) of one side of the discharge tube (insertion port). Then, the opening (insertion port) of the other side of the discharge tube is fused with the enlarged diameter portion of the dielectric, and a discharge container is formed.

[0136] Next, with respect to the process container which is open at both ends and has a flow inlet and a flow outlet formed on both end sides, the discharge container is inserted from the opening portion of one side (from the insertion port), and the large diameter portion of the discharge container is abutted (fitted) to the opening portion. The large diameter portion of the discharge container becomes a support structure that supports the opening portion (end portion) of the process container, and thus the process container and the discharge container are coaxially arranged (temporarily fixed). Then, one end portion (opening portion) of the process container is fused with the large diameter portion of the discharge tube, and the other end portion is fused with the outer peripheral surface of the exhaust pipe.

[0137] Vacuuming is performed through the exhaust pipe to remove impurities. Then, after the discharge gas is enclosed, the exhaust pipe is sealed by heating and deforming, and the outer electrode (reflective film) is arranged on the outer surface between the front end of the fused exhaust pipe and a part of the extension portion.

[0138] In the first to third embodiments, a structure in which a reflective film is provided as an outer electrode is adopted, but an electrode of another mode can be provided.

[0139] Figure 7 is a cross-sectional view showing an excimer lamp of the third modification of the first embodiment. Except for the structure of the outer electrode, the rest is the same structure as the second modification of the first embodiment (refer to Figure 4 ).

[0140] In the excimer lamp 200', the outer electrode 50' is provided to the outer peripheral surface of the processing vessel 230. The outer electrode 50' is spirally wound around the outer peripheral surface of the processing vessel 230 between the electrically conductive cylindrical members 51A, 51B along the lamp axis C, and is arranged in a manner separated at a prescribed interval. According to this structure, the ultraviolet rays are also transmitted inside the tube wall of the processing vessel 230 via the extension portion 262 of the discharge vessel 220 by multiple reflection, and the ultraviolet rays are effectively irradiated to the fluid.

[0141] The excimer lamp described above is characterized in that the processing vessel and the discharge vessel are integrated by being fused together. According to this structure, the flow inlet and flow outlet positions can be set to match the axial length of the inner electrode, that is, the opposing interval (electrode opposing range LI) of the reflection film and the inner electrode, and the space of the flow path R along the lamp axis can be adjusted.

[0142] Further, by forming a thick wall portion around the extension portion of the dielectric or around the outer peripheral surface of the discharge tube, it is possible to suppress the occurrence of lamp breakage starting from the fused portion due to a sharp pressure change of the fluid or the like. Further, it is possible to cause the ultraviolet rays radiated from the discharge space to sufficiently irradiate the fluid flowing into and out of the excimer lamp.

Claims

1. An excimer lamp, characterized in that, The excimer lamp has: A tubular discharge capacitor that forms a discharge space; and The outer container forms a flow path between itself and the discharge capacitor. At least one end of the flow path along the lamp axis is formed at a position closer to the center of the lamp axis than the end of the discharge capacitor.

2. The excimer lamp according to claim 1, characterized in that, At least one end of the flow path along the lamp axis is formed at a position closer to the central side of the lamp axis than the end of the cylindrical portion of the discharge capacitor.

3. The excimer lamp according to claim 2, characterized in that, In the cylindrical portion of the discharge capacitor, the gap distance of the flow path is constant along the lamp axis.

4. The excimer lamp according to claim 3, characterized in that, The gap distance along the radial direction of the flow path is less than the thickness of the outer container.

5. The excimer lamp according to claim 4, characterized in that, The gap distance along the radial direction of the flow path is set to be between 0.2 mm and 2 mm.

6. The excimer lamp according to claim 5, characterized in that, The excimer lamp has a pair of electrodes disposed inside the discharge capacitor and outside the outer container. At least one end of the flow path is formed at a position closer to the lamp axial end side than the range opposite the pair of electrodes.

7. The excimer lamp according to claim 6, characterized in that, The capacitor has an inner electrode. At least one end of the flow path is formed at a position closer to the lamp axial end side than the end of the inner electrode.

8. The excimer lamp according to claim 7, characterized in that, The other end of the flow path extends beyond the end of the cylindrical portion of the discharge capacitor and is formed on the axial end side of the lamp.

9. The excimer lamp according to claim 8, characterized in that, The length of the flow path along the lamp axis is longer than the length of the cylindrical portion along the lamp axis.

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