Gas laser and waste heat recovery system

Abstract

To provide a gas laser and a waste heat recovery system equipped with a new light source that emits excitation light.SOLUTION: A gas laser includes gas as a laser medium, a thermal radiation source having wavelength selectivity and emitting excitation light for exciting the gas by thermal radiation, and an optical resonator that resonates emission light emitted from the gas by the excitation light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to gas lasers and waste heat recovery systems. [Background technology]

[0002] Non-Patent Document 1 discloses a carbon dioxide gas laser excited by a discharge. Non-Patent Document 2 discloses a carbon dioxide gas laser excited by a hydrogen bromide laser.

[0003] Non-Patent Document 3 discloses a thermal radiation source that uses a plasmonic metamaterial. The thermal radiation source has wavelength selectivity. Non-Patent Document 4 discloses a thermal radiation source that emits thermal radiation when heated by electrical current. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] A. Yariv, “Quantum Electronics 3rd Edition”, Wiley (1989) p.216-224 [Non-patent document 2] TY Chang and OR Wood, "Optically pumped atmospheric-pressure CO2 laser", Applied Physics Letters21 (1972) 19 [Non-patent document 3] X. Liu, et al, "Taming theBlackbody with Infrared Metamaterials as Selective Thermal Emitters",Physical Review Letters 107 (2011) 045901 [Non-patent document 4] Ueba, Takahara, "Control of thermal radiation spectrum by metafilament", 74th Autumn Meeting of the Japan Society of Applied Physics, (2013), 18a-C14-7 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors have searched for a new light source that emits excitation light for exciting a gas.

[0006] The present disclosure provides a gas laser and waste heat recovery system with a novel light source that emits excitation light. [Means for solving the problem]

[0007] The gas laser according to the embodiment includes a gas as a laser medium, a wavelength-selective thermal radiation source that emits excitation light for exciting the gas by thermal radiation, and an optical resonator that resonates the emitted light emitted from the gas in response to the excitation light. [Effects of the Invention]

[0008] SUMMARY OF THE INVENTION In accordance with the present disclosure, a gas laser and waste heat recovery system is provided that includes a novel light source that emits excitation light. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically illustrating a gas laser according to an embodiment. [Figure 2] FIG. 2 is a graph showing an example of the thermal radiation spectrum of a thermal radiation source. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a gas laser according to another embodiment. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a plan view showing an example of a thermal radiation source. [Figure 6] FIG. 6 is a plan view showing a part of FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a cross-sectional view schematically showing a gas laser according to another embodiment. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] FIG. 10 is a cross-sectional view schematically showing a gas laser according to another embodiment. [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 12 is a cross-sectional view schematically showing a gas laser according to another embodiment. [Figure 13] FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. [Figure 14] FIG. 14 is a cross-sectional view schematically showing a gas laser according to another embodiment. [Figure 15] FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. [Figure 16] FIG. 16 is a plan view showing an example of a thermal radiation source. [Figure 17] FIG. 17 is a cross-sectional view schematically showing a gas laser according to another embodiment. [Figure 18] FIG. 18 is a cross-sectional view taken along line XVIII-XVIII in FIG. [Figure 19] FIG. 19 is a diagram schematically illustrating a waste heat recovery system according to one embodiment. [Figure 20] FIG. 20 is a diagram schematically illustrating a waste heat recovery system according to another embodiment. [Figure 21] FIG. 21 is a diagram schematically showing a waste heat recovery system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. (1) A gas laser comprising: a gas as a laser medium; a wavelength-selective thermal radiation source that emits excitation light for exciting the gas by thermal radiation; and an optical resonator that resonates the emitted light emitted from the gas in response to the excitation light.

[0011] In the gas laser, the thermal radiation source emits excitation light by thermal radiation. The excitation light causes the gas to emit light that resonates, resulting in the emission of laser light. The gas laser includes a new light source that emits excitation light.

[0012] (2) In the above (1), a heat insulating region may be provided between the gas and the thermal radiation source. In this case, even if the temperature of the thermal radiation source is high, the increase in the gas temperature can be suppressed. Therefore, the decrease in the oscillation efficiency of the laser light can be suppressed.

[0013] (3) In the above (1) or (2), the gas laser may further include a container for accommodating the gas, the container may be cylindrical and extend along an axis, and the thermal radiation source may extend along the axis. In this case, the thermal radiation source can irradiate excitation light toward the gas over a long region along the axis.

[0014] (4) In any one of (1) to (3) above, the gas laser may further include a container for storing the gas, and the inner surface of the container may include a reflective surface for reflecting the excitation light. In this case, the excitation light that reaches the reflective surface without being absorbed by the gas can be reflected back toward the gas.

[0015] (5) In the above (4), the reflecting surface may be disposed so as to face the thermal radiation source. In this case, even if the excitation light reflected by the reflecting surface is not absorbed by the gas, the reflected excitation light returns to the thermal radiation source. Therefore, the energy required to heat the thermal radiation source can be reduced.

[0016] (6) In any one of the above (1) to (5), the thermal radiation source may include a resistance heating element, and the gas laser may further include a power source connected to the resistance heating element. In this case, the thermal radiation source can be heated by applying current.

[0017] (7) In any one of the above (1) to (6), the thermal radiation source may include a conductor, and the gas laser may further include a coil for induction heating the conductor and an AC power supply for supplying AC power to the coil. In this case, the thermal radiation source can be heated without contact.

[0018] (8) In any one of the above (1) to (7), the gas laser may further include an electromagnetic wave generator for irradiating the thermal radiation source with electromagnetic waves to heat the thermal radiation source. In this case, the thermal radiation source can be heated without contact.

[0019] (9) In any one of (1) to (8) above, the gas laser may further include a container for storing the gas, and the container may include a metal member. In this case, the gas can be cooled by the metal member.

[0020] (10) In any one of the above (1) to (9), the gas laser may further include a cooler that cools the gas. In this case, the gas can be cooled in the cooler.

[0021] (11) In any one of (1) to (10) above, the gas laser may further include a container for storing the gas, the thermal radiation source may be disposed outside the container, and the container may include a material that transmits the excitation light. In this case, the degree of freedom in disposing the thermal radiation source is improved.

[0022] (12) A waste heat recovery system comprising a gas laser according to any one of (1) to (11) above and a heating element for heating the thermal radiation source of the gas laser. In this case, the heating element heats the thermal radiation source, causing the thermal radiation source to emit excitation light. As a result, laser light is emitted from the gas laser.

[0023] (13) In the above (12), the waste heat recovery system may further include a photovoltaic cell that converts laser light from the gas laser into electricity. In this case, the waste heat can be recovered and used as electricity.

[0024] (14) In the above (12) or (13), the waste heat recovery system may further include a chemical reaction device to which the laser light from the gas laser is irradiated. In this case, the waste heat can be recovered and used as heat for a chemical reaction.

[0025] [Details of the embodiments of the present disclosure] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0026] FIG. 1 is a schematic diagram illustrating a gas laser according to one embodiment. The gas laser 10 shown in FIG. 1 includes a gas serving as a laser medium, a wavelength-selective thermal radiation source 14, and an optical resonator 16. The gas serving as the laser medium may be contained in a container 12. The thermal radiation source 14 emits excitation light TR for exciting the gas by thermal radiation. The optical resonator 16 can resonate the light emitted from the gas by the excitation light TR. This causes laser light L to be emitted from the gas laser 10.

[0027] The container 12 may be cylindrical and extend along the axis Ax. In one example, the container 12 is a cylinder having an outer diameter of 26 mm, an inner diameter of 24 mm, and a length of 120 mm.

[0028] The thermal radiation source 14 may be disposed outside or inside the container 12. When the thermal radiation source 14 is disposed outside the container 12, the container 12 may include a material that transmits the excitation light TR. The container 12 may include at least one of aluminum oxide, zinc oxide, zinc sulfide, zinc selenide, silicon, calcium fluoride, magnesium fluoride, sodium chloride, polyethylene, polypropylene, and polystyrene. Examples of aluminum oxide include sapphire. The reflectivity of the outer surface of the container 12 with respect to the excitation light TR may be 1% or less. The inner surface of the container 12 may include a reflective surface that reflects the excitation light TR. The reflectivity of the inner surface of the container 12 with respect to the excitation light TR may be 90% or more. The reflective surface may be disposed to face the thermal radiation source 114.

[0029] The optical resonator 16 may be, for example, a Fabry-Perot optical resonator. The optical resonator 16 may include a first mirror M1 and a second mirror M2. The first mirror M1 and the second mirror M2 are arranged facing each other along the axis Ax. The reflectivity of the first mirror M1 for the emitted light is greater than the reflectivity of the second mirror M2 for the emitted light. This allows the laser light L to be emitted from the second mirror M2. In one example, the reflectivity of the first mirror M1 is 95%, and the reflectivity of the second mirror M2 is 90%. The first mirror M1 may cover a first opening of the cylindrical container 12. The first opening is located at a first end of the container 12 along the axis Ax. The second mirror M2 may cover a second opening of the cylindrical container 12. The second opening is located at a second end of the container 12 along the axis Ax. The container 12 and the optical resonator 16 may seal the gas in the container 12. In this case, a device for gas exchange is not required. This allows for a reduction in the size of the gas laser 10. The gas laser 10 can be installed with greater freedom.

[0030] The gas in the container 12 may contain at least one gas selected from the group consisting of carbon dioxide (CO2), nitrogen oxides (N2O, NO2, etc.), sulfur oxides (SO2, etc.), ozone (O3), ammonia (NH3), methane (CH4), and primary alcohols as a laser medium. The gas in the container 12 may be a mixed gas containing a first gas selected from the group consisting of a laser medium and a second gas different from the first gas. The second gas may contain at least one gas selected from the group consisting of helium (He), hydrogen (H2), and water vapor (H2O). The second gas can shift the energy level of the first gas to a lower ground level. The second gas can also cool the first gas. The gas in the container 12 may not contain nitrogen. In one example, the gas in the container 12 contains carbon dioxide (e.g., 50% by volume) and helium (e.g., 50% by volume). The pressure of the gas in the container 12 may be, for example, atmospheric pressure (1×10 5 Pa).

[0031] FIG. 2 is a graph showing an example of the thermal radiation spectrum of a thermal radiation source. The horizontal axis of FIG. 2 represents wavelength. The vertical axis of FIG. 2 represents spectral intensity. The thermal radiation spectrum SP0 shown in FIG. 2 represents an example of the thermal radiation spectrum emitted from a black body. The thermal radiation spectrum SP1 shown in FIG. 2 represents an example of the spectrum of excitation light TR emitted from the thermal radiation source 14. The thermal radiation spectrum SP1 has a first peak in a wavelength range of 3 μm or more (e.g., 4.3 μm). The thermal radiation spectrum SP1 may have a second peak in a wavelength range of 2 to 3 μm. The intensity of the second peak is smaller than the intensity of the first peak.

[0032] The thermal radiation source 14 may include at least one of a photonic crystal, a microcavity, and a plasmonic metasurface. The spectrum of the excitation light TR emitted from the thermal radiation source 14 has a peak at the excitation wavelength of the gas serving as the laser medium.

[0033] The thermal radiation source 14 may be a diamond having a sufficient thickness, or zinc sulfide or zinc selenide doped with a transition metal such as iron or chromium. For example, a diamond having a thickness of about 1 mm can operate as a wavelength-selective radiation source with a wavelength of 4 μm to 6 μm. The thermal radiation source 14 may also be a photonic crystal containing these materials.

[0034] In the gas laser 10, the thermal radiation source 14 emits excitation light TR by thermal radiation. The excitation light TR resonates with the light emitted from the gas, thereby emitting laser light L. Therefore, the gas laser 10 includes the thermal radiation source 14 as a new light source for emitting excitation light TR. The gas laser 10 does not require a high-voltage power supply for discharge, as it does not require a discharge. This allows the gas laser 10 to be made smaller and lighter. Furthermore, in gas lasers other than carbon dioxide lasers, the energy conversion efficiency is low when the gas is excited by discharge or laser. For example, when the gas is excited by laser, the energy conversion efficiency for converting electrical energy into light energy is less than 10%. In contrast, the gas laser 10 excites the gas by thermal radiation, resulting in a high energy conversion efficiency. For example, when the gas is excited by thermal radiation, the energy conversion efficiency for converting electrical energy into light energy is 10% or higher.

[0035] Fig. 3 is a cross-sectional view schematically showing a gas laser according to another embodiment. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. The gas laser 10A shown in Figs. 3 and 4 may have the same configuration as the gas laser 10, except for the following points. The gas laser 10A may include a thermal radiation source 114 and a power supply 30 instead of the thermal radiation source 14. The gas laser 10A may further include a container 18, a sealing member 20, and a protrusion 22.

[0036] The container 18 is disposed outside the container 12. The container 18 is spaced apart from the container 12. The container 18 may be cylindrical and extend along the axis Ax. In one example, the container 18 is a cylinder having an outer diameter of 50 mm, an inner diameter of 46 mm, and a length of 120 mm. The container 12 and the container 18 may form a double pipe.

[0037] The sealing member 20 seals the space between the container 12 and the container 18. One sealing member 20 is disposed between the container 12 and the container 18 at a first end of the container 12 along the axis Ax. In one example, the sealing member 20 is an annular member. Another sealing member 20 is disposed between the container 12 and the container 18 at a second end of the container 12 along the axis Ax. The container 12, the container 18, and the sealing member 20 may be formed by a single member. The space between the container 12 and the container 18 may be evacuated. An inert gas may be sealed in the space between the container 12 and the container 18. Examples of the inert gas include nitrogen, argon, and krypton. The pressure of the inert gas may be 1 Pa or less.

[0038] A gas may be allowed to flow in the space between the container 12 and the container 18 without using the sealing member 20. The gas flows from the first end to the second end of the container 12 along the axis Ax. The gas may be a gas that does not easily absorb the excitation light TR. This makes it easier for the excitation light TR to reach the gas in the container 12.

[0039] The thermal radiation source 114 may be disposed outside the container 12. The thermal radiation source 114 may be disposed between the container 12 and the container 18. A thermal insulation region TIR may be provided between the container 12 and the thermal radiation source 114. The thermal insulation region TIR may be a reduced-pressure space between the container 12 and the container 18. The thermal radiation source 114 may be connected to the container 18 by at least one protrusion 22. A small contact area between the thermal radiation source 114 and the protrusion 22 can suppress heat dissipation from the thermal radiation source 114 to the protrusion 22. Therefore, the thermal radiation source 114 can be heated efficiently. Reducing the number of protrusions 22 can reduce the contact area between the thermal radiation source 114 and the protrusion 22. Reducing the cross-sectional area of ​​the protrusion 22 perpendicular to the protruding direction of the protrusion 22 can reduce the contact area between the thermal radiation source 114 and the protrusion 22.

[0040] The gas laser 10A may include multiple (e.g., eight) heat radiation sources 114. Each heat radiation source 114 may extend along the axis Ax. Each heat radiation source 114 may be a plate-like member having a first surface 114a and a second surface 114b. The first surface 114a is a surface from which the excitation light TR is emitted. The first surface 114a may face the axis Ax and the outer surface of the container 12. The second surface 114b is a surface opposite to the first surface 114a. The second surface 114b may face the inner surface of the container 18. The multiple heat radiation sources 114 may be arranged to surround the axis Ax and the container 12 in a cross section perpendicular to the axis Ax. Adjacent heat radiation sources 114 may be connected to form a single heat radiation source 114. In this case, the heat radiation source 114 may be cylindrical.

[0041] The gas laser 10A may include a power supply 30 connected to the thermal radiation source 114. The power supply 30 is located outside the vessel 18. The power supply 30 may be connected to multiple thermal radiation sources 114 in parallel. The power supply 30 may be a DC power supply. A conductor between the thermal radiation source 114 and the power supply 30 may extend along the protrusion 22.

[0042] When power is supplied from the power supply 30 to each thermal radiation source 114, excitation light TR is emitted from each heated thermal radiation source 114 to the gas in the container 12. The gas is excited by the excitation light TR, and laser light L is emitted from the gas laser 10A. In one example, when a voltage of 5 V is supplied from the power supply 30 to the thermal radiation source 114, laser light L having an output of 0.6 W is emitted. Excitation light TR emitted from one thermal radiation source 114 that is not absorbed by the gas may be incident on another thermal radiation source 114. In this case, a decrease in the temperature of the thermal radiation source 114 to which the excitation light TR is incident is suppressed.

[0043] FIG. 5 is a plan view showing an example of a thermal radiation source. FIG. 6 is a plan view showing a part of FIG. 5. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. As shown in FIGS. 5 to 7, the thermal radiation source 114 may include a substrate SB and a conductor pattern region CP provided on the substrate SB. The substrate SB is, for example, a glass substrate or a polymer substrate. In one example, the substrate SB has a main surface with long sides of 100 mm and short sides of 15 mm, and a thickness of 2 mm.

[0044] The conductor pattern region CP is provided on the first surface 114a of the thermal radiation source 114. The conductor pattern region CP may be a meandering strip-shaped region on the first surface 114a. In one example, the conductor pattern region CP is a strip-shaped region having a width of 2.3 mm that meanders at intervals of 0.2 mm.

[0045] The conductor pattern region CP includes a first layer L1, a second layer L2, and a third layer L3. The first layer L1, the second layer L2, and the third layer L3 are sequentially provided on the substrate SB. The first layer L1 and the second layer L2 may extend over the entire conductor pattern region CP. The first layer L1 may be a metal layer. The first layer L1 is, for example, an aluminum layer. In one example, the first layer L1 has a thickness of 100 nm. The second layer L2 may be a dielectric layer. The second layer L2 is, for example, an aluminum oxide layer. In one example, the second layer L2 has a thickness of 50 nm. The third layer L3 may be a metal layer. The third layer L3 is, for example, an aluminum layer. The third layer L3 may be a plurality of island patterns arranged in an array spaced apart from one another. In one example, the plurality of island patterns are provided at a pitch of 1500 nm. In one example, each island pattern has a square main surface with sides of 980 nm and a thickness of 100 nm.

[0046] The power supply 30 in Figure 3 may be connected to the first layer L1, which is a resistive heating element of the thermal radiation source 114. The positive electrode of the power supply 30 may be connected to a first end of the conductor pattern region CP. The negative electrode of the power supply 30 may be connected to a second end of the conductor pattern region CP. When a current flows through the first layer L1, the conductor pattern region CP is heated.

[0047] Gas laser 10A provides the same effects as gas laser 10. In addition, the following effects are also provided.

[0048] When the heat insulating region TIR is provided between the container 12 and the thermal radiation source 114, it is possible to suppress an increase in the temperature of the gas inside the container 12 even if the temperature of the thermal radiation source 114 is high. Therefore, it is possible to suppress a decrease in the oscillation efficiency of the laser light L.

[0049] When the thermal radiation source 114 extends along the axis Ax, the thermal radiation source 114 can irradiate the excitation light TR toward the gas over a long region along the axis Ax. When the thermal radiation source 114 is provided so as to surround the axis Ax in a cross section perpendicular to the axis Ax, the thermal radiation source 114 can irradiate the excitation light TR toward the gas from many directions.

[0050] When the inner surface of the container 12 includes a reflective surface that reflects the excitation light TR, the excitation light TR that reaches the reflective surface without being absorbed by the gas can be reflected back toward the gas.

[0051] When the reflective surface on the inner surface of the container 12 is disposed so as to face the thermal radiation source 114, even if the excitation light TR reflected by the reflective surface is not absorbed by the gas, the reflected excitation light TR returns to the thermal radiation source 114. Therefore, the energy required to heat the thermal radiation source 114 can be reduced.

[0052] When the thermal radiation source 114 has a first layer L1 and the power supply 30 is connected to the first layer L1, the thermal radiation source 114 can be heated by applying current.

[0053] When the thermal radiation source 114 is disposed outside the container 12 and the container 12 contains a material that transmits the excitation light TR, the degree of freedom in arranging the thermal radiation source 114 is improved.

[0054] Fig. 8 is a cross-sectional view schematically showing a gas laser according to another embodiment. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 8. The gas laser 10B shown in Figs. 8 and 9 may have the same configuration as the gas laser 10A, except for the following points. The gas laser 10B may include a container 112 instead of the container 12. The gas laser 10B may include a dielectric member 118a instead of the container 18.

[0055] The container 112 includes a dielectric member 112a and a metal member 40. The dielectric member 112a and the metal member 40 extend along an axis Ax. In one example, the dielectric member 112a is a semi-cylinder having an outer diameter of 26 mm, an inner diameter of 24 mm, and a length of 120 mm. An example of the material of the dielectric member 112a is the same as the example of the material of the container 12 in FIG. 1.

[0056] The metal member 40 is, for example, an aluminum member. The metal member 40 may be a plate-shaped member extending along the axis Ax. The metal member 40 has a recess RS1 extending along the axis Ax. An inner surface 40b of the recess RS1 forms a part of the inner surface of the container 112. In one example, the inner surface 40b is the inner surface of a semicylinder having an inner diameter of 26 mm. The inner surface 40b may be a reflective surface that reflects the excitation light TR. The reflectivity of the inner surface 40b with respect to the excitation light TR may be 90% or more. The inner surface 40b may be arranged to face the thermal radiation source 114.

[0057] The gas laser 10A may include a dielectric member 118a disposed outside the dielectric member 112a. The dielectric member 118a is spaced apart from the dielectric member 112a. The dielectric member 118a may extend along the axis Ax. In one example, the dielectric member 118a is a semi-cylinder having an outer diameter of 50 mm, an inner diameter of 46 mm, and a length of 120 mm. An example of the material of the dielectric member 118a is the same as the example of the material of the container 18 in FIG. 3.

[0058] The metal member 40 may be connected to the dielectric member 112a and the dielectric member 118a. The metal member 40 and the sealing member 20 may seal the space between the dielectric member 112a and the dielectric member 118a. The thermal radiation source 114 may be disposed in the space between the dielectric member 112a and the dielectric member 118a. The thermal radiation source 114 may be connected to the dielectric member 118a by at least one protrusion 22.

[0059] The metal member 40 may include a flow path 40a for flowing a cooling fluid. The cooling fluid may include water. In one example, the temperature of the cooling fluid is room temperature (25°C).

[0060] Gas laser 10B provides the same effects as gas laser 10A. Furthermore, gas laser 10B can cool the gas inside vessel 112 using metal member 40. If metal member 40 includes flow path 40a, the gas cooling effect is enhanced.

[0061] Fig. 10 is a cross-sectional view schematically showing a gas laser according to another embodiment. Fig. 11 is a cross-sectional view taken along line XI-XI in Fig. 10. The gas laser 10C shown in Figs. 10 and 11 may have the same configuration as the gas laser 10A, except for the following points. The gas laser 10C may include a container 212 instead of the container 12. The gas laser 10C may include a thermal radiation source 214 instead of the thermal radiation source 114. The gas laser 10C may further include a cooler 50. The gas laser 10C may not include the power supply 30.

[0062] The container 212 includes a main body 212a, a gas supply pipe 212b connected to the main body 212a, and a gas exhaust pipe 212c connected to the main body 212a. The main body 212a may have the same configuration as the container 12 except for the following points: The main body 212a may have a first opening connected to the gas supply pipe 212b and a second opening connected to the gas exhaust pipe 212c.

[0063] The cooler 50 is connected to the gas supply pipe 212b and the gas exhaust pipe 212c. The cooler 50 exchanges heat with the gas G in the container 212. This cools the gas G. The gas G circulates between the container 212 and the cooler 50 through the gas supply pipe 212b and the gas exhaust pipe 212c.

[0064] The thermal radiation source 214 may be disposed outside the container 18. The thermal radiation source 214 may extend along the axis Ax. The thermal radiation source 214 may be provided to surround the container 18. The thermal radiation source 214 may be a cylindrical member extending along the axis Ax. The thermal radiation source 214 may have a first surface 214a and a second surface 214b. The first surface 214a is a surface from which the excitation light TR is emitted. The first surface 214a faces the outer surface of the container 18. The first surface 214a may be in contact with the outer surface of the container 18. The second surface 214b is a surface opposite to the first surface 214a. The second surface 214b is a surface that recovers heat from a heating element located outside the gas laser 10C. The second surface 214b may be in contact with the heating element. In this case, the thermal radiation source 214 is heated by heat transfer. The second surface 214b may be separated from the heating element. In this case, the thermal radiation source 214 is heated by thermal radiation from the heating element. The temperature of the heating element may be 300°C or higher. The thermal radiation source 214 may be disposed inside the container 18. The gas laser 10C may not include the container 18. In this case, the thermal radiation source 214 also functions as the container 18.

[0065] Gas laser 10C can achieve the same effects as gas laser 10A. Furthermore, gas laser 10C can cool the gas in container 212 using cooler 50. Gas laser 10C can emit laser light L using heat emitted from a heat source using heat radiation source 214. There is no need to supply power to heat radiation source 214 from power supply 30.

[0066] In other gas lasers 10, 10A, 10B, a thermal radiation source 214 may be used, thereby eliminating the need for power supply 30.

[0067] In other gas lasers 10, 10A, 10B, the vessel 212 and cooler 50 may be used to cool the gas within the vessel 212.

[0068] Fig. 12 is a cross-sectional view schematically showing a gas laser according to another embodiment. Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 12. The gas laser 10D shown in Figs. 12 and 13 may have the same configuration as the gas laser 10B, except for the following points. The gas laser 10D may include a thermal radiation source 214 instead of the thermal radiation source 114. The gas laser 10D may include a metal member 42 instead of the dielectric member 118a. The gas laser 10D may include a heat insulating material 44. The gas laser 10D may not include the power supply 30.

[0069] The metal member 42 may be disposed outside the container 112. The metal member 42 is, for example, an aluminum member. The metal member 42 may be a plate-shaped member extending along the axis Ax. The metal member 42 has a recess RS2 extending along the axis Ax. An inner surface 42b of the recess RS2 faces the dielectric member 112a. The inner surface 42b is spaced apart from the dielectric member 112a. In one example, the inner surface 42b is the inner surface of a semicylinder having an inner diameter of 100 mm. A thermal radiation source 214 is provided between the inner surface 42b and the dielectric member 112a.

[0070] The metal member 42 may have a flow path 42a for flowing a high-temperature fluid. The high-temperature fluid may include a high-temperature gas such as steam. In one example, the temperature of the high-temperature fluid is 300°C. The metal member 42 may be heated by a heating element. In this case, the metal member 42 does not need to have the flow path 42a. The heating element may be in contact with the metal member 42 or may be separated from the metal member 42.

[0071] The insulating material 44 may be disposed between the metal member 40 and the metal member 42. The insulating material 44 may connect the metal member 40 and the metal member 42 to each other. The insulating material 44 may extend along the axis Ax. The insulating material 44 may include, for example, porous calcium silicate.

[0072] The container 112, the metal member 42, and the thermal insulator 44 may seal the space between the dielectric member 112a and the inner surface 42b.

[0073] Gas laser 10D can provide the same effects as gas laser 10B. Furthermore, gas laser 10D can heat heat radiation source 214 by means of metal member .

[0074] In other gas lasers 10, 10A, 10B, and 10C, a metal member 42 and a heat radiation source 214 may be used, thereby eliminating the need for a power supply 30.

[0075] FIG. 14 is a cross-sectional view schematically showing a gas laser according to another embodiment. FIG. 15 is a cross-sectional view taken along line XV-XV in FIG. 14. The gas laser 10E shown in FIGS. 14 and 15 may have the same configuration as the gas laser 10A, except for the following points. The gas laser 10E may include a thermal radiation source 314 instead of the thermal radiation source 114. The gas laser 10E may include a heating device 130 instead of the power supply 30. The gas laser 10E may include a container 12 having a rectangular parallelepiped outer shape. The gas laser 10E may include a container 18 having a rectangular parallelepiped outer shape.

[0076] In a cross section perpendicular to the axis Ax, the container 12 has a rectangular outer shape. In a cross section perpendicular to the axis Ax, the thermal radiation source 314 may extend along the long sides of the rectangle of the container 12. The thermal radiation source 314 may also extend along the short sides of the rectangle of the container 12, or may not be disposed on the short sides of the rectangle. Even if the thermal radiation source 314 is disposed only on the long sides of the rectangle of the container 12, the gas in the container 12 can be excited with high efficiency.

[0077] The thermal radiation source 314 may be disposed between the container 12 and the container 18. The thermal radiation source 314 may be a plate-like member having a first surface 314a and a second surface 314b. The first surface 314a is a surface from which the excitation light TR is emitted. The first surface 314a faces the axis Ax and the outer surface of the container 12. The second surface 314b is a surface opposite to the first surface 314a. The second surface 314b faces the inner surface of the container 18.

[0078] Fig. 16 is a plan view showing an example of a heat radiation source. The heat radiation source 314 shown in Fig. 16 may include a substrate SB and a conductor pattern region CP1 provided on the substrate SB. The conductor pattern region CP1 is provided on a first surface 314a of the heat radiation source 314. The conductor pattern region CP1 has the same configuration as the conductor pattern region CP, except that it is provided in a spiral shape on the first surface 314a.

[0079] 14 and 15, the heating device 130 includes a coil 132 for inductively heating the conductors of the thermal radiation source 314 (e.g., the first layer L1 and the third layer L3 of the conductor pattern area CP1), and an AC power supply 134 for supplying AC power to the coil 132. The coil 132 may be a spiral coil. The spiral coil has a pattern corresponding to the conductor pattern area CP1. The coil 132 faces the conductor pattern area CP1 of the thermal radiation source 314. In one example, the frequency of the AC power supply 134 is 50 Hz.

[0080] The gas laser 10E provides the same effects as the gas laser 10A. Furthermore, the gas laser 10E allows the heating device 130 to heat the heat radiation source 314 in a non-contact manner. This reduces the amount of heat that is released from the heat radiation source 314 to the outside through the conductor. This allows the heat radiation source 314 to be heated efficiently. If the coil 132 is a spiral coil having a pattern corresponding to the conductor pattern region CP1, the efficiency of energy conversion from electrical energy to thermal energy can be improved.

[0081] The thermal radiation source 314 and the heating device 130 may be used in other gas lasers 10, 10A, 10B, 10C, and 10D, so that the thermal radiation source 314 can be heated without contact.

[0082] In other gas lasers 10, 10A, 10B, 10C, and 10D, a container 12 having a rectangular parallelepiped outer shape and a container 18 having a rectangular parallelepiped outer shape may be used.

[0083] Fig. 17 is a cross-sectional view schematically showing a gas laser according to another embodiment. Fig. 18 is a cross-sectional view taken along line XVIII-XVIII in Fig. 17. The gas laser 10F shown in Figs. 17 and 18 may have the same configuration as the gas laser 10A, except for the following points. The gas laser 10F may include an electromagnetic wave irradiator 230 instead of the power supply 30.

[0084] The electromagnetic wave irradiator 230 irradiates the thermal radiation source 114 with electromagnetic waves to heat the thermal radiation source 114. The electromagnetic wave irradiator 230 includes an antenna 232 that emits electromagnetic waves and a high-frequency power supply 234 connected to the antenna 232. In one example, the frequency of the high-frequency power supply 234 is 2.4 GHz. The frequency of the electromagnetic waves emitted from the electromagnetic wave irradiator 230 may be from 100 Hz to 10 GHz. For example, the thermal radiation source 114 can be heated by dielectric heating by irradiating it with microwaves. The thermal radiation source 114 may include a dielectric material. Each of the container 12 and the container 18 may include a material that is transparent to electromagnetic waves.

[0085] The gas laser 10F can achieve the same effects as the gas laser 10A. Furthermore, the gas laser 10F can heat the heat radiation source 114 in a non-contact manner using the electromagnetic wave irradiator 230. This can suppress the heat that is released from the heat radiation source 114 to the outside through the conductor. This allows the heat radiation source 114 to be heated efficiently.

[0086] The electromagnetic wave irradiator 230 may be used in the other gas lasers 10, 10A, 10B, 10C, 10D, and 10E, thereby allowing the heat radiation source 14, 114, and 214 to be heated without contact.

[0087] FIG. 19 is a schematic diagram illustrating a waste heat recovery system according to one embodiment. The waste heat recovery system 100 shown in FIG. 19 includes a gas laser 10 and a heating element HD for heating the thermal radiation source 14 of the gas laser 10. The waste heat recovery system 100 may include multiple gas lasers 10. The heating element HD may be in contact with the thermal radiation source 14 or may be spaced apart from the thermal radiation source 14. The heating element HD may be a high-temperature solid or a high-temperature fluid. The waste heat recovery system 100 may also include an optical absorber LA that absorbs laser light L emitted from each gas laser 10. The optical absorber LA may be at least one of a photovoltaic cell and a chemical reactor.

[0088] In the waste heat recovery system 100, the heat radiation source 14 of the gas laser 10 is heated by the heat generating element HD, causing the heat radiation source 14 to emit excitation light TR. As a result, laser light L is emitted from each gas laser 10. The laser light L is irradiated toward the light absorber LA and absorbed by the light absorber LA. Therefore, the waste heat of the heat generating element HD can be recovered and utilized in the light absorber LA. Because the laser light L has high focusing ability, the laser light L from multiple gas lasers 10 can be focused into a narrow area. Therefore, the temperature of the light absorber LA can be made higher than the temperature of the heat generating element HD. The heat generating element HD may have a large surface area for heat dissipation. In this case, the number of gas lasers 10 that can be installed can be increased. This allows the temperature of the light absorber LA to be increased.

[0089] The waste heat recovery system 100 may include gas lasers 10, 10A, 10B, 10C, 10D, 10E, and 10F instead of the gas laser 10.

[0090] FIG. 20 is a schematic diagram illustrating a waste heat recovery system according to another embodiment. The waste heat recovery system 100A shown in FIG. 20 includes a gas laser 10, water vapor HW as a heating element for heating the thermal radiation source 14 of the gas laser 10, and a photovoltaic cell LA1 for converting laser light L from the gas laser 10 into electricity. The waste heat recovery system 100A may include multiple gas lasers 10. The water vapor HW is generated by heating water using the heat dissipation section HP of the device AP. The water vapor HW flows from the heat dissipation section HP toward the gas laser 10. The water vapor HW is cooled by heating the thermal radiation source 14. The cooled water vapor HW is supplied to a condenser CD where it condenses. The condensed water is returned to the device AP by a pump PM.

[0091] In the waste heat recovery system 100A, the heat radiation source 14 is heated by the water vapor HW, causing the heat radiation source 14 to emit excitation light TR. As a result, laser light L is emitted from the gas laser 10. The laser light L is irradiated toward the photocell LA1 and converted into electricity in the photocell LA1. The waste heat recovery system 100A allows waste heat to be recovered and used as electricity. Because the laser light L has high focusing properties, the laser light L from multiple gas lasers 10 can be focused into a narrow area. This allows for increased power generation by the photocell LA1. The power generation efficiency of the photocell LA1 can also be improved.

[0092] The waste heat recovery system 100A may include gas lasers 10, 10A, 10B, 10C, 10D, 10E, and 10F instead of the gas laser 10.

[0093] FIG. 21 is a schematic diagram showing a waste heat recovery system according to another embodiment. The waste heat recovery system 100B shown in FIG. 21 may be a system for synthesizing ammonia by the Haber-Bosch process. The waste heat recovery system 100B includes a gas laser 10, ammonia gas NH as a heating element for heating the thermal radiation source 14 of the gas laser 10, and a chemical reaction device RA to which laser light L from the gas laser 10 is irradiated. The chemical reaction device RA may include a catalyst CT. In one example, the temperature of the catalyst CT is 500°C. The catalyst CT includes iron, aluminum oxide, and potassium oxide.

[0094] The waste heat recovery system 100B includes a gas supply source GS that supplies nitrogen and hydrogen to a chemical reactor RA. A compressor CM is disposed between the gas supply source GS and the chemical reactor RA. The nitrogen and hydrogen supplied from the gas supply source GS are compressed in the compressor CM and then supplied to the chemical reactor RA. In the chemical reactor RA, the nitrogen and hydrogen react with each other in the presence of a catalyst CT to synthesize ammonia gas NH. In one example, the temperature of the ammonia gas NH in the chemical reactor RA is 480°C. The ammonia gas NH is supplied to a gas laser 10 and heats a thermal radiation source 14 of the gas laser 10. The ammonia gas NH is cooled by heating the thermal radiation source 14. The cooled ammonia gas NH is supplied to a cooler CL and cooled there. The cooled ammonia gas NH is supplied to a condenser CD and condenses there. The condensed ammonia is returned to the compressor CM by a pump PM.

[0095] According to the waste heat recovery system 100B, the heat radiation source 14 is heated by the ammonia gas NH, causing the heat radiation source 14 to emit excitation light TR. As a result, laser light L is emitted from the gas laser 10. The laser light L is irradiated toward the chemical reaction device RA and heats the catalyst CT in the chemical reaction device RA. This reduces the energy required to heat the catalyst CT. In this way, according to the waste heat recovery system 100B, waste heat can be recovered and used as heat for chemical reactions.

[0096] The waste heat recovery system 100B may include gas lasers 10, 10A, 10B, 10C, 10D, 10E, and 10F instead of the gas laser 10.

[0097] Although the preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments.

[0098] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0099] 10...Gas laser 10A...Gas laser 10B...Gas laser 10C...Gas laser 10D...Gas laser 10E...Gas laser 10F...Gas laser 12...Container 14...Thermal radiation source 16...Optical resonator 18…Container 20...Sealing member 22...Protrusion 30...Power supply 40...Metal parts 40a...flow path 40b...Inner 42...Metal parts 42a...flow path 42b...Inner 44...Insulation material 50...Cooler 100...Waste heat recovery system 100A...Waste heat recovery system 100B...Waste heat recovery system 112...Container 112a...Dielectric member 114...Thermal radiation source 114a…First page 114b…Second side 118a...Dielectric member 130...Heating device 132...Coil 134…AC power supply 212…Container 212b...Gas supply pipe 212c...Gas exhaust pipe 214…Thermal radiation source 214a…First page 214b…Second side 230...Electromagnetic wave irradiator 232...Antenna 234...High frequency power supply 314…Thermal radiation source 314a…First page 314b…Second side AP…device Ax…Axis CD...Condenser CL…Cooler CM...Compressor CP: Conductive pattern area CP1: Conductive pattern area CT…Catalyst G...gas GS...Gas supply source HD…heating element HP...Heat radiation part HW...water vapor L...laser light L1…1st layer L2…Second layer L3…Third layer LA...light absorber LA1...Photocell M1...1st mirror M2: Second mirror NH...ammonia gas PM…Pump RA: Chemical reactor RS1…Concave RS2…recess SB...Substrate SP0...thermal radiation spectrum SP1: Thermal radiation spectrum TIR: Thermal insulation region TR…Excitation light

Claims

1. a gas as a laser medium; a wavelength-selective thermal radiation source that emits excitation light for exciting the gas by thermal radiation; an optical resonator for resonating emitted light emitted from the gas in response to the excitation light; A gas laser comprising:

2. 10. The gas laser of claim 1, further comprising an insulating region between said gas and said thermal radiation source.

3. Further comprising a container for containing the gas; The container has a cylindrical shape extending along an axis, 3. A gas laser as claimed in claim 1 or 2, wherein the thermal radiation source extends along the axis.

4. Further comprising a container for containing the gas; 3. The gas laser according to claim 1, wherein the inner surface of the vessel includes a reflective surface that reflects the excitation light.

5. 5. The gas laser of claim 4, wherein the reflective surface is positioned to face the thermal radiation source.

6. the thermal radiation source comprises a resistive heating element; 3. The gas laser of claim 1, further comprising a power supply connected to the resistive heating element.

7. the thermal radiation source comprises a conductor; a coil for inductively heating the conductor; an AC power source for supplying AC power to the coil; 3. The gas laser of claim 1, further comprising:

8. 3. The gas laser of claim 1, further comprising an electromagnetic wave generator for irradiating said thermal radiation source with electromagnetic waves to heat said thermal radiation source.

9. Further comprising a container for containing the gas; 3. The gas laser of claim 1, wherein the vessel comprises a metal member.

10. 3. The gas laser of claim 1, further comprising a cooler for cooling the gas.

11. Further comprising a container for containing the gas; the thermal radiation source is located outside the vessel; 3. The gas laser according to claim 1, wherein the container includes a material that transmits the excitation light.

12. a gas laser according to claim 1 or 2; a heating element for heating the thermal radiation source of the gas laser; A waste heat recovery system comprising:

13. 13. The waste heat recovery system of claim 12, further comprising a photovoltaic cell for converting laser light from the gas laser into electricity.

14. The waste heat recovery system according to claim 12 , further comprising a chemical reaction device that is irradiated with laser light from the gas laser.

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