JP7634922B2 - Excimer lamp, method for lighting an excimer lamp, and method for manufacturing an excimer lamp - Google Patents

Description

The present invention relates to an excimer lamp, and in particular to the configuration of the discharge space.

A double-tube structure lamp is known among excimer lamps (see Patent Document 1). In this lamp, a dielectric covering a foil-shaped inner electrode is placed inside the discharge tube, and a voltage is applied between the outer electrode and inner electrode provided on the outer surface of the discharge tube. This causes excimer light such as ultraviolet light to be emitted from the discharge space formed between the dielectric and the discharge tube.

In addition, to ensure that high-output excimer lamps are lit, an excimer lamp is known that is equipped with a start-up assistance function that discharges at a voltage lower than the discharge start voltage (see Patent Document 2). In this lamp, a start-up assistance discharge space filled with a gas with a low starting voltage is formed along the lamp axis direction within the inner tube of the double-tube structure lamp. Ultraviolet light emitted from the start-up assistance discharge space irradiates the gas in the main discharge space, causing a discharge in the main discharge space.

JP 2012-38658 A JP 2017-4702 A

In the case of a lamp configuration in which the starting-assistance discharge space is formed over the entire inner tube, the main discharge space and the starting-assistance discharge space are formed concentrically, which places limitations on the size of the discharge tube. As a result, for example, it may be difficult to place an excimer lamp inside the jacket tube with only a small gap between them.

Therefore, there is a need to provide an excimer lamp that can be adapted to a variety of usage environments while improving the lamp's lighting startability.

The excimer lamp according to one aspect of the present invention comprises a dielectric covering a foil electrode arranged along the lamp axis direction, and a discharge vessel that is welded to the dielectric to form a main discharge space, and the dielectric has an extension that extends from an end of the discharge vessel. In the extension, the foil electrode is partially sealed to the dielectric so that an auxiliary discharge space is formed inside the dielectric. Here, "sealed" refers to welding the foil electrode to the dielectric so that it is sealed (hermetically sealed).

The auxiliary discharge space can be formed between the surface of the inner electrode and the inner surface of the dielectric so that the electric field strength varies along at least one of the lamp axial direction and the lamp circumferential direction. For example, the electric field strength can be varied by the cross-sectional shape of the foil electrode, the way in which the spatial region changes near the boundary between the auxiliary discharge space and the sealed portion of the foil electrode and the dielectric, etc.

For example, the foil electrode can be formed so that its edge is narrower than its center (e.g., in a knife-edge shape). In this case, the edge of the foil electrode can be configured to be separated from the inner surface of the dielectric in the auxiliary discharge space, making it possible to vary the electric field strength along the circumferential direction of the lamp. Alternatively, the edge of the foil electrode can be sealed to the dielectric in the auxiliary discharge space, making it possible to vary the electric field strength along the lamp axial direction near the boundary.

The foil electrode can be constructed as a single unit, or as multiple foil electrodes. For example, the foil electrode can be constructed as a first electrode portion disposed inside the discharge vessel, and a second electrode portion electrically connected to the first foil electrode portion by a power supply line or the like and disposed inside the extension portion.

The discharge vessel can be configured, for example, so that the tip of the dielectric fits into a small diameter portion provided at the tip of the discharge vessel, and the tip of the foil electrode along the lamp axis is located rearward of the small diameter portion.

The auxiliary discharge space can be formed so that the distance between the dielectric and the foil electrode along the width direction of the foil electrode is shorter on the edge side than in the center. Also, the auxiliary discharge space can be formed so that the distance between the dielectric and the foil electrode along the length direction of the foil electrode is shorter on the end side than in the center.

In one aspect of the present invention, a method for lighting an excimer lamp involves forming an auxiliary discharge space between the surface of the inner electrode and the inner surface of the inner tube in an extension extending from the enlarged diameter portion of the inner tube to the outside of the outer tube, and irradiating a portion of the light emitted from the auxiliary discharge space in the lamp axial direction to the main discharge space through the tip of the inner tube on the main discharge space side and the enlarged diameter portion.

The manufacturing method of an excimer lamp according to one aspect of the present invention includes the steps of inserting a foil-shaped inner electrode into a glass tube that will become the inner tube, sealing the inner tube by reducing the pressure inside the inner tube or sealing a rare gas in the inner tube at atmospheric pressure or less, heating and reducing the diameter of the inner tube to partially fuse the inner tube to the inner electrode so that an auxiliary discharge space is formed at least partially along the axial direction of the inner tube, and inserting the inner tube into the glass tube that will become the discharge tube and fusing the outer tube to the inner tube so that a portion of the inner tube extends from the discharge tube.

The present invention provides an excimer lamp that can be adapted to a variety of usage environments while improving the lamp's lighting startability.

1 is a schematic cross-sectional view of the excimer lamp of the present embodiment as viewed from the side. 1 is a schematic cross-sectional view of an excimer lamp according to an embodiment of the present invention, as viewed from the axial direction. 1 is a schematic cross-sectional view of the excimer lamp of the present embodiment as viewed from the side.

Below, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a schematic cross-sectional view of an excimer lamp according to this embodiment as viewed from the side. Figure 1 is a schematic cross-sectional view of an excimer lamp according to this embodiment as viewed from the axial direction. Figure 2 corresponds to a cross-sectional view taken along line B-B in Figure 1. The cross-sectional view in Figure 1 corresponds to a cross-sectional view taken along a line passing through the central axis of the lamp in Figure 2.

The excimer lamp 10 includes a discharge vessel 10T formed by an outer tube 20 and an inner tube 50, both of which are made of a dielectric material such as quartz glass and have a substantially cylindrical cross section. A foil electrode (hereinafter referred to as the inner electrode) 30 extending in a strip shape having a width along the tube radial direction (hereinafter also referred to as the lamp radial direction) is covered by a columnar dielectric (hereinafter referred to as the inner tube) 50 along the tube axis (hereinafter also referred to as the lamp axis) C. The inner electrode 30 is not exposed to the annular discharge space (hereinafter referred to as the main discharge space) S1 formed between the outer tube 20 and the inner tube 50. Here, the inner tube 50 is formed to have a substantially circular cross section.

The excimer lamp 10 has a portion (hereinafter referred to as an extension portion) 52 that is not covered by the outer tube 20 and extends beyond the end 20T2 of the discharge vessel 10T (outer tube 20) along the lamp axis C, and the power supply line 70 passes through the inside of the end 50T2. However, the extension portion 52 may be formed by welding a separate member different from the inner tube 50. The small diameter portion 22 formed during the lamp manufacturing process protrudes from the discharge vessel 10T (outer tube 20) toward the lamp tip along the lamp axis C.

The diameter of the small diameter portion 22 is smaller than the diameter of the discharge vessel 10T, i.e., a portion of the lamp axial range, and is smaller than the diameter of the range along the lamp axial direction in which the outer electrode 40 is disposed (herein referred to as the axial arrangement range). Here, the tip side of the outer tube 20 is heated and deformed to reduce its diameter, and a tip tube with a smaller diameter than the outer tube 20 is welded to form the small diameter portion 22 integrally with the discharge vessel 10T. Note that the tip tube used in lamp manufacturing may be provided in a position separate from the small diameter portion.

In this embodiment, the end 50T1 of the inner tube 50 enters the small diameter portion 22 and contacts the small diameter portion 22. Therefore, the inner tube 50 is stably held coaxially within the outer tube 20. In addition, the outer surface of the end 50T1 of the inner tube 50 has a tapered convex curved surface, and the inner surface of the small diameter portion 22 has a tapered concave curved surface.

This allows them to be stably held coaxially without damage even in the event of dimensional errors caused by the respective heat forming processes. While forming such a fitted state, the position of the tip 30T1 of the inner electrode 30 along the lamp axis C is located toward the rear end (center of the discharge vessel) of the small diameter portion 22, without penetrating into the internal space of the small diameter portion 22.

An electrode (hereinafter referred to as the outer electrode) 40 is disposed on the outer surface 20S of the outer tube 20. The outer electrode 40 is configured in this case by winding a linear electrode portion made of a conductive metal along the surface of the outer tube 20, and is wound in a spiral shape along the tube axis C at a predetermined interval.

The axial arrangement range L of the outer electrode 40 is determined to be 20T0, which is a constant inner diameter portion between the tapered ends 20T1 and 20T2 of the outer tube 20 (hereinafter referred to as the cylindrical portion). The axial length of the inner electrode 30 corresponds to the axial arrangement range L of the outer electrode 40. The power supply line 70 connected to the end of the inner electrode 30 is connected to an externally installed power supply unit (not shown), and power is supplied to the excimer lamp 10 via the power supply line 70.

By applying a high frequency (e.g., in the range of several kHz to several tens of MHz) and a high voltage (e.g., in the range of several kV to several tens of kV) to the inner electrode and the outer electrode, excimer light is emitted from the discharge space S1. Here, ultraviolet light (e.g., wavelength 172 nm) is emitted outside the discharge vessel. Therefore, the excimer lamp 10 can be used in an ozone generator that generates ozone to sterilize and deodorize, and can also be used in an ultraviolet irradiation device that directly irradiates an object with ultraviolet light.

A discharge space S2 for assisting in starting the lamp (hereinafter referred to as the auxiliary discharge space) is formed in the extension 52. As shown in FIG. 1, a portion of the extension 52 of the inner tube 50 along the lamp axis C is not partially welded (sealed) all around the circumferential direction of the inner electrode 30. On the other hand, both axial ends 30T1 and 30T2 of the inner electrode 30 are sealed to the inner tube 50 all around. This forms the auxiliary discharge space S2.

Here, the range M (auxiliary discharge space range) of the auxiliary discharge space S2 along the lamp axis C is determined to be a section outside the axial arrangement range of the inner electrode 30 corresponding to the axial arrangement range L of the outer electrode 40. That is, in the axial arrangement range L of the outer electrode 40, in the ranges of both ends 30T1, 30T2 of the inner electrode 30, the inner electrode 30 is sealed to the inner tube 50 around the entire circumferential direction. In contrast, in the middle part of the extension 52 of the inner tube 50, the entire outer peripheral surface of the inner electrode 30 is exposed, and the auxiliary discharge space S2 is formed to surround it. In addition, in the auxiliary discharge space range M, the outer diameter of the inner tube 50 is larger than in other ranges.

At both ends ST1, ST2 of the inner surface of the inner electrode 30 exposed to the auxiliary discharge space S2 (both ends of the auxiliary discharge space range M), the distance between the inner electrode 30 and the inner tube 50 gradually decreases, and the discharge space area narrows toward both ends 50T1, 50T2 of the inner tube 50. The inner electrode 30 is sealed to the inner tube 50 while the distance between the inner surface of the inner tube 50 and the outer surface of the inner electrode 30 gradually decreases. The outer diameter of the inner tube 50 also gradually decreases, and the outer surface forms a smoothly curved surface.

The spatial shape of the auxiliary discharge space S2 has a wider radial cross-sectional area toward the center of the lamp (auxiliary discharge space range M), and the spatial area narrows toward the small diameter portion 22 and the extension portion 52 at both ends of the discharge vessel 10T. Therefore, the distance L1 along the lamp diameter direction between the outer peripheral surface of the inner tube 50 and the inner peripheral surface of the inner tube 50 in the central portion along the lamp axis C of the auxiliary discharge space S2 is longer than the distance L2 at both ends ST1, ST2 of the inner surface of the inner tube 50 exposed to the auxiliary discharge space S2.

In addition, both edges 30T3, 30T4 of the foil-like inner electrode 30 are knife-edge shaped, and the inner electrode 30 becomes sharp from the center in the width direction toward the edge (end), and its thickness becomes thinner than the thickness at the center in the width direction, and both edges 30T3, 30T4 are sharp.

Therefore, the auxiliary discharge space S2 has a wider radial cross-sectional area toward the center in the width direction (lamp radial direction) of the inner electrode 30 (see FIG. 2). Therefore, the length of the distance between the inner surface of the inner electrode 30 and the outer surface of the inner tube 50 along the lamp radial direction is longer in the thickness direction near the center (lamp central axis) than in the width direction near both edges 30T3 and 30T4 of the inner electrode 30 (corresponding to L1 in FIG. 1). The distance T1 is longer in the thickness direction near the center (lamp central axis).

That is, the auxiliary discharge space S2 (discharge space regions S2A, S2B) narrows toward the ends 30T1, 30T2 in the length direction (lamp axis direction) along the surface of the foil-shaped inner electrode 30 and toward the edges 30T3, 30T4 in the width direction (lamp radial direction).

The auxiliary discharge space S2 is in a reduced pressure state lower than atmospheric pressure, or a rare gas (lower than atmospheric pressure) that lowers the voltage at the start of lighting is enclosed in the auxiliary discharge space S2. When a high-frequency high voltage is applied between the inner electrode 30 and the outer electrode 40, a discharge occurs first in the auxiliary discharge space S2 due to the reduced pressure state of the auxiliary discharge space S2, with a lighting start voltage lower than that of the main discharge space S1. Then, a portion of the light (ultraviolet light in this case) emitted from the auxiliary discharge space S2 in the lamp axial direction is irradiated to the main discharge space S1 through the inner tube 50.

Moreover, most of the space between both ends 30T1, 30T2 of the inner electrode 30 is in contact with the inner tube 50 while embedded therein, and parts of both edges 30T3, 30T4 of the inner electrode 30 are exposed to the auxiliary discharge space S2, forming a spatial region with high electric field strength in the auxiliary discharge space S2, which is in a reduced pressure state. This ensures that a discharge occurs in the auxiliary discharge space S2 with a lower lighting start voltage than the main discharge space S1. It also reduces the power required during lamp lighting, and suppresses wear due to discharge on the inner electrode 30 (particularly the edges).

A portion of the light emitted in the lamp axial direction from the discharge generated in the auxiliary discharge space S2 is repeatedly reflected inside the tube wall of the inner tube 50 (at the boundary surface of the tube wall), and is transmitted toward the end 50T1 of the inner tube 50 due to the so-called fiber effect. A portion of the ultraviolet light transmitted by the fiber effect passes through the expanded diameter portion 51 of the inner tube 50 and is irradiated from the end 20T2 of the outer tube 20 into the main discharge space S1.

In addition, part of the light emitted in the lamp axial direction is irradiated from the end 20T1 of the outer tube 20 through the end 50T1 of the inner tube 50 into the main discharge space S1 from the end 20T1 of the outer tube 20, because the end 50T1 of the inner tube 50 partially enters and contacts the small diameter portion 22. The ultraviolet light transmitted by this fiber effect is irradiated into the main discharge space S1, causing a discharge in the main discharge space S1. In this way, by forming an auxiliary discharge space S2 in part of the extension 52 of the inner tube 50, the lighting start-up performance is improved.

Here, the auxiliary discharge space S2 is formed as a minute discharge space region where the radiated light reaches the main discharge space S1, and is not formed as a discharge space region having a space occupying most of the extension portion 52 of the inner tube 50. However, because the auxiliary discharge space S2 is formed in an adjacent position along the lamp axis direction outside the discharge vessel 10T, the voltage applied between the inner electrode 30 and the outer electrode 40 is suppressed while the lamp is lit (while the main discharge is occurring). By suppressing the required power, the lamp durability and lamp life can be improved.

In addition, since the auxiliary discharge space S2 is formed coaxially with the inner tube 50, light is irradiated from both ends 50T1 and 50T2 of the inner tube 50 from the auxiliary discharge space S2 toward the main discharge space S1. This allows a stable main discharge to occur in the main discharge space S1.

The illuminance distribution (light distribution) along the outer periphery of the discharge vessel varies depending on the shape of the discharge vessel and the position of the discharge generated inside it. Furthermore, the discharge state is affected by the electric field strength distribution determined by the relative positions of the electrodes (anode and cathode) and the shapes of the inner tube and auxiliary discharge space. However, the above-mentioned excimer lamp 10 does not change the outer shape or discharge state of a conventional excimer lamp with a double-tube structure, so it is possible to improve the lighting startability in ultraviolet irradiation devices and ozone generators without affecting lamp characteristics such as discharge maintenance voltage and illuminance distribution or the power supply characteristics suitable for them.

Illumination startability can be understood by the certainty (probability [%]) that, when a voltage is applied to an excimer lamp, a stable illumination state in which the desired radiation spectrum is obtained from the discharge in the discharge vessel is reached. Excimer lamps require certainty of illumination startability (100% reliability) even in low temperature conditions, in darkness, or after a long period of inactivity. In this embodiment, however, a stable illumination state can be reliably reached without using a large illumination power supply or a light source for auxiliary illumination start-up, meaning that illumination start-up can be achieved with virtually 100% certainty.

The formation spatial region of the auxiliary discharge space S2 in the extension portion 52, and the formation section M along the lamp axis C can be adjusted as appropriate. For example, by welding only the two edge portions 30T3, 30T4 of the inner electrode 30 to the inner tube 50 so that they are not exposed, two discharge space regions S2A, S2B spatially separated by the foil-shaped inner electrode 30 can be formed as the auxiliary discharge space S2. In addition, the surface of the inner electrode may be coated (covered) with a dielectric material for the specified auxiliary discharge space range M, so that the two edge portions 30T3, 30T4 of the inner electrode 30 are not exposed to the auxiliary discharge space S2.

Such an excimer lamp 10 can be manufactured, for example, by the following manufacturing method.

A glass tube (inner tube) with a cylindrical cross section that serves as a covering for the foil electrode (inner electrode) is formed from a dielectric material that is transparent to the light emitted from the discharge formed in the auxiliary discharge space. After the inner tube is formed, a power supply wire is connected to the foil electrode by resistance welding or the like, and the foil electrode is inserted into the cylindrical glass tube with a bottom.

After inserting the foil electrode that will become the inner electrode into the glass tube that will become the inner tube, the glass tube is reduced in pressure (vacuum) and sealed. At this time, a rare gas may be sealed inside the glass tube at atmospheric pressure or below. Then, while rotating the glass tube, it is heated to soften and shrink (reduced in diameter) so that an auxiliary discharge space is partially formed at the end of the glass tube, and the glass tube and the inner electrode are partially fused together.

In this case, by bringing only the edges of the foil electrode along the width direction (tube diameter direction) into close contact with the inner surface of the glass tube, the edges of the foil electrode are not exposed, and a space where the glass tube and the foil electrode are not in contact can be formed as an auxiliary discharge space.

One end of the glass tube that will become the inner tube is heated to form a brim-shaped (so-called abacus bead-shaped) enlarged diameter section. Alternatively, the glass tube may not be rotated, and only the part of the glass tube that faces the inner circumferential surface and the edge of the foil electrode may be heated along the axial direction to seal them together. The end of the foil electrode along its length (tube axis direction) is sealed in the entire circumferential direction, so that the end of the foil electrode is embedded in the glass tube and is not exposed to the auxiliary discharge space.

As for the outer tube, one end of the quartz tube, which is transparent to the wavelengths of ultraviolet light emitted from the discharge formed in the main discharge space, is reduced in diameter and an open introduction tube (tip tube) is provided, while the outer tube is formed with an open sealing section with the expanded diameter section of the inner tube.

Then, the inner tube is inserted into the outer tube so that they are coaxially arranged, and the discharge tube and the expanded diameter section of the inner tube are heat-fused together to form a discharge vessel. After that, a vacuum is drawn through the introduction tube to remove impurities, and the discharge vessel is filled with discharge gas, and the introduction tube is heat-melted to hermetically seal it. After that, the outer electrode is placed on the outer surface of the outer tube.

In this embodiment, the inner electrode 30 extends into the discharge vessel 10T and into the extension portion 52, but different inner electrodes may be disposed in the discharge vessel 10T and the extension portion 52.

Figure 3 is a schematic cross-sectional view of a modified excimer lamp of this embodiment, viewed from the side. Here, two foil-shaped inner electrodes 30A, 30B are connected by an internal power supply line 71. The inner electrode 30B is provided in an extension 52 of the inner tube 50 located outside the outer tube 20. The inner electrodes 30A, 30B face each other, and their radial cross-sectional positions (extension directions) are the same.

As in this embodiment, an auxiliary discharge space S2 is formed in the extension 52 of the inner tube 50. Even when two inner electrodes 30A, 30B are provided in this manner, the lamp can be lit and its performance can be improved, as in this embodiment. In addition, by using the internal power supply wire 71, the power consumed while the lamp is lit can be further reduced.

The enlarged diameter portion 51 has a larger outer diameter (wall thickness) than the other portions of the inner tube 50, and is difficult to reduce in diameter by heating. Therefore, by disposing the internal power supply wire 71 in the enlarged diameter portion 51, it is possible to achieve both thermal reduction of the internal power supply wire 71 in the enlarged diameter portion 51 and welding to the end portion 20T2 of the outer tube 20, making manufacturing easier.

In addition, the portions of the inner electrodes 30A and 30B where the electric field is concentrated, particularly the knife-edge shaped edges 30T3 and 30T4, are spaced apart from the enlarged diameter portion 51. By spacing the inner electrodes 30A and 30B apart from the enlarged diameter portion 51 in this way, it is possible to reliably prevent abnormal discharge (creeping discharge) near the end 20T2 of the outer tube.

The outer electrodes may be embedded in the inner wall of the discharge tube so as to face each other, or one may be embedded and the other disposed on the outer surface of the discharge tube. In addition, the light emitted from the auxiliary discharge space is not limited to ultraviolet light, and may be visible light.

10 Excimer lamp 20 Outer tube 30 Inner electrode (foil electrode)
40 Outer electrode 50 Inner tube (dielectric)
70 Power supply line 71 Internal power supply line

Claims (11)

a dielectric covering the foil electrodes disposed along the lamp axial direction;
a discharge vessel that is fused to the dielectric to form a main discharge space,
the dielectric has an extension extending from an end of the discharge vessel,
an excimer lamp comprising: said foil electrode and said dielectric body; said foil electrode being partially sealed to said dielectric body in said extending portion so as to form an auxiliary discharge space that is closed as a space inside said dielectric body; The excimer lamp of claim 1, characterized in that the auxiliary discharge space is formed between the surface of the foil electrode and the inner surface of the dielectric such that the electric field strength varies along at least one of the lamp axial direction and the lamp circumferential direction. An excimer lamp as described in claim 1 or 2, characterized in that the edge of the foil electrode is separated from the inner surface of the dielectric in the auxiliary discharge space. The excimer lamp according to claim 1 or 2, characterized in that the edge of the foil electrode is sealed to the dielectric in the auxiliary discharge space. An excimer lamp according to any one of claims 1 to 4, characterized in that the foil electrode has a first electrode portion disposed inside the discharge vessel and a second electrode portion electrically connected to the first electrode portion and disposed inside the extension portion. a dielectric covering the foil electrodes disposed along the lamp axial direction;
a discharge vessel that is fused to the dielectric to form a main discharge space,
the dielectric has an extension extending from an end of the discharge vessel,
In the extension portion, the foil electrode is partially sealed to the dielectric so that an auxiliary discharge space is formed inside the dielectric,
The tip position of the tip of the dielectric body enters into a small diameter portion provided at the tip of the discharge vessel,
2. An excimer lamp according to claim 1, wherein a tip position of said foil electrode along the lamp axis is located rearward of said small diameter portion. a dielectric covering the foil electrodes disposed along the lamp axial direction;
a discharge vessel that is fused to the dielectric to form a main discharge space,
the dielectric has an extension extending from an end of the discharge vessel,
In the extension portion, the foil electrode is partially sealed to the dielectric so that an auxiliary discharge space is formed inside the dielectric,
An excimer lamp characterized in that the auxiliary discharge space is formed so that the distance between the dielectric and the foil electrode along the width direction of the foil electrode is shorter at the edge side than at the center. a dielectric covering the foil electrodes disposed along the lamp axial direction;
a discharge vessel that is fused to the dielectric to form a main discharge space,
the dielectric has an extension extending from an end of the discharge vessel,
In the extension portion, the foil electrode is partially sealed to the dielectric so that an auxiliary discharge space is formed inside the dielectric,
An excimer lamp characterized in that the auxiliary discharge space is formed so that the distance between the dielectric and the foil electrode along the longitudinal direction of the foil electrode is shorter at the ends than at the center. An excimer lamp comprising an inner tube covering a foil electrode disposed along the lamp axis, and an outer tube fused to an enlarged diameter portion of the inner tube to form a main discharge space between the inner tube and the outer tube,
an auxiliary discharge space is formed between a surface of the foil electrode and an inner surface of the inner tube in an extension portion extending from the expanded diameter portion to the outside of the outer tube;
A method for operating an excimer lamp, comprising the steps of: irradiating a portion of the light emitted from the auxiliary discharge space in the lamp axial direction to the main discharge space through the tip of the inner tube on the main discharge space side and the expanded diameter portion. inserting a foil-shaped inner electrode into a glass tube that will become an inner tube;
a step of reducing the pressure inside the inner tube and sealing it, or sealing a rare gas in the inner tube at atmospheric pressure or lower;
a step of heating the inner tube and reducing its diameter so as to partially fuse the inner tube to the inner electrode so that an auxiliary discharge space is formed at least partially along the tube axis direction inside the inner tube;
and a step of inserting the inner tube into a glass tube which serves as a discharge tube, and fusing an outer tube to the inner tube so that a portion of the inner tube extends from the discharge tube and the auxiliary discharge space is located outside the discharge tube. 11. The method for manufacturing an excimer lamp according to claim 10, wherein the discharge tube is heat-fused integrally with the enlarged diameter portion of the inner tube to form a main discharge space.

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