Self-guided gas target and high harmonic generation device

Abstract

The application discloses a self-guiding gas target and a high harmonic generation device. The gas target body of the self-guiding gas target is internally formed with a first cavity, a light transmission hole and a second cavity which are in communication with each other. A first metal breakdown wall covers the light inlet side of the first cavity, and a second metal breakdown wall covers the light outlet side of the second cavity. A first gas extraction device is connected with the first metal breakdown wall and used for discharging the gas diffused into the first gas extraction device from the gas target body. A second gas extraction device is connected with the second metal breakdown wall and used for discharging the gas diffused into the second gas extraction device from the gas target body. The self-guiding gas target is guided in a self-guiding mode, so that the driving laser directly breaks through the metal breakdown wall to realize light transmission. The first gas extraction device and the second gas extraction device are connected with the relevant gas extraction device, which can effectively improve the high harmonic conversion efficiency, greatly reduce the absorption loss after the generation of the high harmonic, and thus realize the generation of the high harmonic with high photon flux.

Description

Technical Field

[0001] This application relates to the field of high-order harmonic technology, and in particular to a self-guided gas target and a high-order harmonic generation device. Background Technology

[0002] Higher harmonic radiation, a type of high-order nonlinear, non-perturbative radiation generated by the interaction of femtosecond laser pulses with matter, possesses excellent directionality and coherence. It also offers advantages such as tabletop compatibility, miniaturization, and low cost, making it a highly promising method for generating extreme ultraviolet (EUV) light sources. It holds significant application value in nanotechnology imaging, semiconductor detection, and quantum computer chip development.

[0003] However, current research on high-harmonic light sources still faces key challenges such as low conversion efficiency and low photon flux, which limit the further promotion of high-harmonic light sources in practical applications. Summary of the Invention

[0004] This application discloses a self-guided gas target and a high-order harmonic generation device, which can improve the conversion efficiency of high-order harmonics and greatly reduce the absorption loss of the generated high-order harmonics by the gas in the non-interactive region, thereby realizing the generation of high-photon flux high-order harmonics.

[0005] To achieve the above objectives, this application provides the following technical solution: In a first aspect, this application provides a self-guided gas target for generating high-order harmonics by interacting with a driving laser that enters the target and the gas. The target includes a first pumping device, a first metal penetration wall, a gas target body, a second metal penetration wall, and a second pumping device arranged sequentially along the optical path. Along the optical path, the gas target body has a first chamber, a light-transmitting hole, and a second chamber that are interconnected. A first metal-broken wall covers the light-incident side of the first chamber to allow the driving laser to enter the first chamber. A second metal-broken wall covers the light-exit side of the second chamber to allow the driving laser to leave the second chamber. The first metal-broken wall, the first chamber, the light-transmitting hole, the second chamber, and the second metal-broken wall cooperate to form a gas pool. An air inlet channel is also formed inside the gas target body, and the air inlet channel is connected to the gas pool. The first pumping device is connected to the first metal penetration wall and is used to discharge the gas that diffuses into the first pumping device from the gas pool after the driving laser penetrates the first metal penetration wall. The second pumping device is connected to the second metal penetration wall and is used to discharge the gas that diffuses into the second pumping device from the gas pool after the driving laser penetrates the second metal penetration wall.

[0006] The aforementioned self-guided gas target, through self-guidance, allows the driving laser to directly penetrate the sidewall of the gas target body, achieving light transmission. Furthermore, the gas target body is connected to a related pumping device, which not only effectively improves the high-order harmonic conversion efficiency but also significantly reduces absorption loss after high-order harmonic generation, thereby achieving high-photon flux high-order harmonic generation. The self-guided gas target of this application includes a first pumping device, a first metal penetration wall, a gas target body, a second metal penetration wall, and a second pumping device arranged sequentially along the optical path. Specifically, along the optical path, the gas target body has a first chamber, a light-transmitting hole, and a second chamber that are interconnected. The first metal penetration wall covers the light-incident side of the first chamber to allow the driving laser to enter the first chamber; the second metal penetration wall covers the light-exit side of the second chamber to allow the driving laser to leave the second chamber. The first metal penetration wall, the first chamber, the light-transmitting hole, the second chamber, and the second metal penetration wall cooperate to form a gas pool. An inlet channel is also formed inside the gas target body, and the inlet channel communicates with the gas pool. The driving laser interacts with the gas in the gas cell to generate higher harmonics, which continue to propagate coaxially with the remaining driving laser.

[0007] In application, a relevant focusing module can be used to focus the driving laser near the first and second metal-broken walls. It can be understood that the first and second metal-broken walls are thin metal walls. Since the driving laser is already focused into a relatively small spot near the first and second metal-broken walls, it can directly penetrate them to enter or leave the gas pool. This process of the driving laser directly penetrating the first and second metal-broken walls to form a light-transmitting hole is what we call self-guiding. Compared with the traditional method of drilling holes in the sidewalls, on the one hand, the light-transmitting hole formed by the driving laser directly penetrating the sidewalls in this application is smaller in size, which can improve the sealing of the gas target body, reduce gas leakage, maintain stable gas pressure in the gas pool, optimize the phase matching process of high-order harmonic generation, and improve the conversion efficiency of high-order harmonics; on the other hand, this application does not require the driving laser to be aligned with a pre-drilled light-transmitting hole on the gas target body, greatly simplifying the alignment process.

[0008] The first pumping device is connected to the first metal-broken wall and is used to discharge the gas diffused into the first pumping device from the gas pool after the driving laser breaks through the first metal-broken wall. The second pumping device is connected to the second metal-broken wall and is used to discharge the gas diffused into the second pumping device from the gas pool after the driving laser breaks through the second metal-broken wall. By setting the first pumping device and the second pumping device on the front and rear sides of the gas target body, this application can remove the gas diffused into the first pumping device and the second pumping device after the driving laser breaks through the first metal-broken wall and the second metal-broken wall, thereby reducing the influence of the rarefied gas in the non-interactive area on the driving laser and the absorption loss of the generated high-order harmonics, thus realizing the generation of high-photon flux high-order harmonics. Furthermore, when the self-guided gas target of this application is applied to a vacuum chamber, the first pumping device and the second pumping device can also reduce the amount of gas diffused into the vacuum chamber, reducing the pumping pressure of the vacuum pump connected to the vacuum chamber.

[0009] In some embodiments, the dimension of the first air extraction device along the optical path direction is larger than the dimension of the second air extraction device along the optical path direction.

[0010] In some embodiments, the length of the light-transmitting hole is 1mm-9mm.

[0011] In some embodiments, a cooling channel is also formed inside the gas target body for dissipating heat from the gas target body.

[0012] In some embodiments, the first pumping device has a window at one end away from the gas target body, and the light-incident side of the window is coated with an anti-reflection film.

[0013] In some embodiments, the second pumping device has a metal step on the side away from the gas target body, and a differential aperture is formed inside the metal step, which is coaxially arranged with the optical path.

[0014] In some embodiments, the thickness of the metal step along the optical path direction is 4 to 10 times the diameter of the differential aperture.

[0015] In some embodiments, sealing rings are provided between the first air extraction device and the gas target body, and between the second air extraction device and the gas target body.

[0016] In some embodiments, the first metal penetration wall, the gas target body, and the second metal penetration wall are integrally formed.

[0017] Secondly, this application provides a device for generating higher harmonics, comprising: Used to excite driving lasers that generate higher harmonics; A vacuum chamber, with a through-conducting flange installed on its cavity wall; A first vacuum pump is located outside the vacuum chamber and connected to the vacuum chamber; A second vacuum pump is located outside the vacuum chamber; As described in the first aspect, the self-guided gas target is disposed inside the vacuum chamber. Both the first and second pumping devices have pumping pipes, and the pumping pipes are connected to the second vacuum pump through the through-flange. The gas source is located outside the vacuum chamber and is connected to the gas inlet channel of the gas target body. Attached Figure Description

[0018] Figure 1 A schematic diagram of a high-order harmonic generation device provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a gas target body provided in an embodiment of this application; Figure 3 A schematic diagram of the structure of a gas target body and a second pumping device provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of a second air extraction device provided in an embodiment of this application; Icons: 1. Driving laser; 2. First pumping device; 3. First metal penetration wall; 4. Gas target body; 41. First chamber; 42. Light transmission hole; 43. Second chamber; 5. Second metal penetration wall; 6. Second pumping device; 7. Gas pool; 8. Inlet channel; 9. Window; 10. Metal step; 11. Differential aperture; 12. Cooling channel; 13. Sealing ring; 01. Vacuum chamber; 02. First vacuum pump; 03. Second vacuum pump; 04. Through-guide flange; 05. Self-guided gas target; 06. Gas source. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. In the description of the embodiments of this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0021] Firstly, such as Figures 1-4 As shown, this application provides a self-guided gas target for generating high-order harmonics by having a driving laser 1 enter it interact with the gas. The target includes a first pumping device 2, a first metal penetration wall 3, a gas target body 4, a second metal penetration wall 5, and a second pumping device 6 arranged sequentially along the optical path. Along the optical path, the gas target body 4 has a first chamber 41, a light-transmitting hole 42, and a second chamber 43 that are interconnected. A first metal penetration wall 3 covers the light-incident side of the first chamber 41 to allow the driving laser 1 to enter the first chamber. A second metal penetration wall 5 covers the light-exit side of the second chamber 43 to allow the driving laser 1 to leave the second chamber 43. The first metal penetration wall 3, the first chamber 41, the light-transmitting hole 42, the second chamber 43, and the second metal penetration wall 5 cooperate to form a gas pool 7. An air inlet channel 8 is also formed inside the gas target body 4, and the air inlet channel 8 is connected to the gas pool 7. The first pumping device 2 is connected to the first metal penetration wall 3 and is used to discharge the gas that diffuses into the first pumping device 2 from the gas pool 7 after the driving laser 1 penetrates the first metal penetration wall 3. The second pumping device 6 is connected to the second metal penetration wall 5 and is used to discharge the gas that diffuses into the second pumping device 6 from the gas pool 7 after the driving laser 1 penetrates the second metal penetration wall 5.

[0022] The aforementioned self-guided gas target enables the driving laser 1 to directly penetrate the sidewall of the gas target body 4 to achieve light transmission through a self-guided method. Furthermore, the gas target body 4 is connected to a related gas extraction device, which can not only effectively improve the high-order harmonic conversion efficiency, but also greatly reduce the absorption loss after the generation of high-order harmonics, thereby achieving high-photon flux high-order harmonic generation.

[0023] like Figure 1 and Figure 2As shown, the self-guided gas target of this application includes a first pumping device 2, a first metal-pierced wall 3, a gas target body 4, a second metal-pierced wall 5, and a second pumping device 6 arranged sequentially along the optical path. Specifically, along the optical path, the gas target body 4 has a first chamber 41, a light-transmitting hole 42, and a second chamber 43 that are interconnected. The first metal-pierced wall 3 covers the light-incident side of the first chamber 41 to allow the driving laser 1 to enter the first chamber 41; the second metal-pierced wall 5 covers the light-exit side of the second chamber 43 to allow the driving laser 1 to leave the second chamber 43. The first metal-pierced wall 3, the first chamber 41, the light-transmitting hole 42, the second chamber 43, and the second metal-pierced wall 5 cooperate to form a gas pool 7. An air intake channel 8 is also formed inside the gas target body 4, and the air intake channel 8 is connected to the gas pool 7. The driving laser 1 interacts with the gas in the gas pool 7 to generate higher harmonics, which continue to propagate coaxially backward with the remaining driving laser 1.

[0024] In application, a relevant focusing module can be used to focus the driving laser 1 near the first metal-pierced wall 3 and the second metal-pierced wall 5. It can be understood that the first metal-pierced wall 3 and the second metal-pierced wall 5 are thin metal walls. Since the driving laser 1 is already focused into a relatively small spot near the first metal-pierced wall 3 and the second metal-pierced wall 5, it can directly penetrate the first metal-pierced wall 3 and the second metal-pierced wall 5 to enter or leave the gas cell 7. This process of the driving laser 1 directly penetrating the first metal-pierced wall 3 and the second metal-pierced wall 5 to form a light-transmitting hole is what we call self-guiding. Compared with the traditional method of drilling holes in the sidewalls, on the one hand, the light-transmitting hole formed by the driving laser 1 directly penetrating the sidewalls in this application is smaller in size, generally in the tens to hundreds of nanometers range. This can improve the sealing performance of the gas target body 4, reduce gas leakage, maintain stable gas pressure in the gas cell, optimize the phase matching process of high-order harmonic generation, and improve the conversion efficiency of high-order harmonics. On the other hand, this application does not require the driving laser 1 to be aligned with a pre-drilled light-transmitting hole on the gas target body 4, greatly simplifying the light alignment process.

[0025] The first pumping device 2 is connected to the first metal-pierced wall 3 and is used to discharge the gas diffused into the first pumping device 2 from the gas pool 7 after the driving laser 1 penetrates the first metal-pierced wall 3. The second pumping device 6 is connected to the second metal-pierced wall 5 and is used to discharge the gas diffused into the second pumping device 6 from the gas pool 7 after the driving laser 1 penetrates the second metal-pierced wall 5. By setting the first pumping device 2 and the second pumping device 6 on the front and rear sides of the gas target body 4, this application can remove the gas diffused into the first pumping device 2 and the second pumping device 6 after the driving laser 1 penetrates the first metal-pierced wall 3 and the second metal-pierced wall 5, thereby reducing the influence of the rarefied gas in the non-interactive area on the driving laser 1 and the absorption loss of the generated high-order harmonics, thus realizing the generation of high-order harmonics with high photon flux. Furthermore, when the self-guided gas target of this application is applied to the vacuum chamber 01, the first pumping device 2 and the second pumping device 6 can also reduce the amount of gas diffused into the vacuum chamber 01, reducing the pumping pressure of the first vacuum pump 02 connected to the vacuum chamber 01.

[0026] It should be noted that, as Figure 3 As shown, in another possible implementation, the first metal breakdown wall 3 and the second metal breakdown wall 5 can also be disposed on the light-incident side and the light-outcident side of the light-passing aperture 42. That is, the specific positions of the first metal breakdown wall 3 and the second metal breakdown wall 5 can be adjusted according to the actual situation to make the conversion efficiency of higher harmonics higher and realize the generation of higher harmonics with high photon flux.

[0027] In some embodiments, such as Figure 1 As shown, a window 9 is provided at the end of the first extraction device 2 away from the gas target body 4, designed to allow the driving laser 1 to enter the first extraction device 2 and protect the driving laser 1 from the influence of the external environment. An antireflection film (not shown in the figure) is coated on the light-incident side of the window 9 to reduce the reflection and absorption of the driving laser 1, reduce stray light, and increase light transmittance. It should be noted that the installation method of the window 9 on the first extraction device 2 is not specifically limited.

[0028] In some embodiments, the second pumping device 6 is provided with a metal step 10 on the side away from the gas target body 4, and a differential aperture 11 is formed inside the metal step 10, which is coaxially arranged with the optical path.

[0029] One possible way to achieve this is, such as Figure 1 and Figure 4As shown, since high-order harmonics in the extreme ultraviolet band are easily absorbed by any medium, the second pumping device 6 of this application has a metal step 10 on the side away from the gas target body 4. A differential aperture 11 is formed inside the metal step 10 to allow the generated high-order harmonics and the remaining driving laser 1 to pass through together. The specific structure needs to be designed in conjunction with the structure of the gas target body 4. The differential aperture 11 is coaxially arranged with the optical path, and the diameter of the differential aperture 11 matches the spot size of the driving laser 1 after it diverges through the second metal penetration wall 5, which can prevent the remaining driving laser 1 from hitting the metal step 10 and causing heat generation.

[0030] In some embodiments, the dimension of the first air extraction device 2 along the optical path direction is larger than the dimension of the second air extraction device 6 along the optical path direction.

[0031] One possible way to achieve this is, such as Figure 1 As shown, along the optical path, the length of the first evacuation device 2 is greater than the length of the second evacuation device 6. In application, the length of the first evacuation device 2 should be designed to be as long as possible to avoid damage to the window 9 due to it being too close to the focal point of the driving laser 1. The length of the second evacuation device 6 should be as short as possible to ensure that the differential aperture 11 is closer to the focal point of the driving laser 1, so that the spot of the driving laser 1 passing through the differential aperture 11 is as small as possible, thus reducing gas flow. For example, as... Figure 4 As shown, the maximum length of the second air extraction device 6 along the optical path can be 39 mm.

[0032] In some embodiments, such as Figure 2 As shown, the length L1 of the light-transmitting aperture 42 is 1mm-9mm.

[0033] For example, the length of the light-transmitting aperture 42 can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, etc., and the specific size is not limited. It should be noted that the aperture size of the light-transmitting aperture 42 is usually made relatively large to better maintain the uniformity and stability of the gas pressure in the gas pool 7. Depending on the actual application, the aperture size of the light-transmitting aperture 42 can also be designed to other suitable sizes.

[0034] The length L1 of the aperture 42 significantly affects the phase matching of higher harmonic generation. Different driving laser powers and gas media correspond to different optimal gas target body lengths 4. By fabricating multiple gas target bodies 4 with different L1 lengths to optimize the phase matching of higher harmonics, the best higher harmonic generation efficiency can be achieved. The minimum length L1 of the aperture 42 can be 1.5 mm, and can be adjusted to be longer as needed. The self-guided gas target of this application can be adapted to various application environments for higher harmonic generation, thereby optimizing the higher harmonic generation efficiency under high-power and high-repetition-frequency laser driving conditions.

[0035] In some embodiments, a cooling channel 12 is also formed inside the gas target body 4 for dissipating heat from the gas target body 4.

[0036] One possible way to achieve this is, such as Figure 1 and Figure 2 As shown, the gas target body 4 is also designed with a cooling channel 12 to suppress the adverse effects of the temperature rise in the gas target body 4 after the driving laser 1 penetrates the first metal penetration wall 3 and the second metal penetration wall 5. It is understood that the cooling channel 12 has threads near the outer surface of the gas target body 4 for connection with a cooling medium, such as water. It should be noted that the cooling channel 12 should be designed as close as possible to the light-transmitting hole 42 to ensure that the temperature of the interaction zone between the driving laser 1 and the gas does not become too high, thereby reducing the thermal effects when the high-power driving laser penetrates the gas target body 4.

[0037] In some embodiments, the thickness of the metal step 10 along the optical path direction is 4 to 10 times the aperture of the differential aperture 11.

[0038] One possible way to achieve this is, such as Figure 1 and Figure 4 As shown, in this application, the wall thickness of the metal step 1 is set to 4 to 10 times the aperture of the differential aperture 11. For example, the aperture of the differential aperture 11 can be 2.5 mm, and correspondingly, the thickness of the metal step 10 is 10 mm. This setting can reduce airflow, thereby reducing the diffusion of gas from the gas pool 7 from the gas target body 4 into the second pumping device 6, reducing the absorption loss of high-order harmonics generated by the gas in the non-active area, further reducing the diffusion of gas into the vacuum chamber 01, and reducing the pumping pressure of the first vacuum pump 02 connected to the vacuum chamber 01.

[0039] In some embodiments, sealing rings 13 are provided between the first air extraction device 2 and the gas target body 4, and between the second air extraction device 6 and the gas target body 4.

[0040] One possible way to achieve this is, such as Figure 3As shown, both the gas target body 4 and the second pumping device 6 have screw holes at their assembly positions. The sealing ring 13 is pressed against the surface of the gas target body 4 by screws, thereby achieving a vacuum seal. Similarly, the installation method between the first pumping device 2 and the gas target body 4 is the same as that between the second pumping device 6 and the gas target body 4, and will not be described again here. It should be noted that the sealing ring 13 in this application can be a sealing part such as a rubber ring.

[0041] It should be noted that the sides of the first and second pumping devices 2 and 6 facing the gas target body 4 are both designed with a conical structure to ensure proper installation and matching between the first and second pumping devices 2 and 6 and the gas target body 4. The sides of the first and second pumping devices 2 and 6 facing away from the gas target body 4 are both designed with a cylindrical structure to match the diverging laser beam and to allow for faster pumping.

[0042] In some embodiments, the first metal penetration wall 3, the gas target body 4, and the second metal penetration wall 5 are integrally formed.

[0043] In one possible implementation, the first metal penetration wall 3 and the second metal penetration wall 5 of the gas target body 4 can be designed as an integral copper structure with the gas target body 4 to facilitate heat dissipation.

[0044] Of course, in another possible implementation, the first metal penetration wall 3 and the second metal penetration wall 5 can also be designed as separate metal sheets that are connected to the gas target body 4 by means of fixing with high thermal conductivity vacuum adhesive, etc. After use, they can be removed and replaced with new metal sheets to realize the reuse of the structure of the gas target body 4.

[0045] Secondly, such as Figure 1 As shown, this application embodiment provides a high-order harmonic generation device, including: 1. A driving laser used to generate higher harmonics; Vacuum chamber 01, with a through-conducting flange 04 installed on its cavity wall; The first vacuum pump 02 is located outside the vacuum chamber 01 and connected to the vacuum chamber 01; The second vacuum pump 03 is located outside the vacuum chamber 01; For example, the self-guided gas target 05 of the first aspect is set inside the vacuum chamber 01. The first pumping device 2 and the second pumping device 6 both have pumping pipes (not shown in the figure). The pumping pipes are connected to the second vacuum pump 03 through the through-flange 04. The gas source 06 is located outside the vacuum chamber 01 and is connected to the gas inlet channel 8 of the gas target body 4.

[0046] The gas inlet channel 8 of the gas target body 4 in this application is also equipped with a pressure fine-tuning valve and a vacuum gauge for finely adjusting the gas density in the gas pool 7 during the generation of higher harmonics. The gas can be different gases such as neon (Ne) or argon (Ar), or a mixture of several gases, depending on the requirements of the subsequent application for the harmonic wavelength and intensity. The first vacuum pump 02 can be a pump assembly such as a molecular pump or a mechanical pump, used to maintain the vacuum level in the vacuum chamber 01 at 1 × 10⁻⁶. -2 Below mbar.

[0047] The high-order harmonic generation device of this application has been applied to a laser-driven high-order harmonic generation device with an average power of 120W, generating high-order harmonics with an average power of 38W in the wavelength range of 8nm-15nm, and achieving a conversion efficiency of 3.5×10⁻⁶. -7 .

[0048] The high-harmonic generation device of this application is suitable for various high-harmonic generation conditions. The gas cell 7 can be filled with various different gases or gas mixtures, and the gas pressure adjustment range can be from tens of mbars to two atmospheres, allowing it to withstand high-power and high-repetition-frequency laser-driven environments. This provides favorable conditions for further optimization of high-harmonic light sources, lays the foundation for achieving higher photon flux high-harmonics, and is expected to be applied in various research fields such as attosecond science, femtosecond spectroscopy, and high-resolution imaging technology.

[0049] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A self-guided gas target for generating high-order harmonics by interacting with a driving laser entering it and the gas, characterized in that, It includes a first pumping device, a first metal penetration wall, a gas target body, a second metal penetration wall, and a second pumping device arranged sequentially along the optical path. Along the optical path, the gas target body has a first chamber, a light-transmitting hole, and a second chamber that are interconnected. A first metal-broken wall covers the light-incident side of the first chamber to allow the driving laser to enter the first chamber. A second metal-broken wall covers the light-exit side of the second chamber to allow the driving laser to leave the second chamber. The first metal-broken wall, the first chamber, the light-transmitting hole, the second chamber, and the second metal-broken wall cooperate to form a gas pool. An air inlet channel is also formed inside the gas target body, and the air inlet channel is connected to the gas pool. The first pumping device is connected to the first metal penetration wall and is used to discharge the gas that diffuses into the first pumping device from the gas pool after the driving laser penetrates the first metal penetration wall. The second pumping device is connected to the second metal penetration wall and is used to discharge the gas that diffuses into the second pumping device from the gas pool after the driving laser penetrates the second metal penetration wall.

2. The self-guided gas target according to claim 1, characterized in that, The dimension of the first air extraction device along the optical path is larger than the dimension of the second air extraction device along the optical path.

3. The self-guided gas target according to claim 1, characterized in that, The length of the light-transmitting hole is 1mm-9mm.

4. The self-guided gas target according to claim 1, characterized in that, The gas target body also has a cooling channel inside for dissipating heat from the gas target body.

5. The self-guided gas target according to claim 1, characterized in that, The first gas extraction device has a window at one end away from the gas target body, and the light-incident side of the window is coated with an anti-reflection film.

6. The self-guided gas target according to claim 1, characterized in that, The second gas extraction device has a metal step on the side away from the gas target body, and a differential aperture is formed inside the metal step. The differential aperture is coaxially arranged with the optical path.

7. The self-guided gas target according to claim 6, characterized in that, The thickness of the metal step along the optical path is 4 to 10 times the diameter of the differential aperture.

8. The self-guided gas target according to claim 1, characterized in that, A sealing ring is provided between the first air extraction device and the gas target body, and between the second air extraction device and the gas target body.

9. A device for generating higher harmonics, characterized in that, include: Used to excite driving lasers that generate higher harmonics; A vacuum chamber, with a through-conducting flange installed on its cavity wall; A first vacuum pump is located outside the vacuum chamber and connected to the vacuum chamber; A second vacuum pump is located outside the vacuum chamber; The self-guided gas target as described in any one of claims 1-8 is disposed inside the vacuum chamber, and both the first and second pumping devices have pumping pipes, the pumping pipes being connected to the second vacuum pump via the through-flange. The gas source is located outside the vacuum chamber and is connected to the gas inlet channel of the gas target body.

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