A megawatt level radio frequency fast-axis flow CO2 laser

Abstract

The application discloses a ten-thousand-watt radio frequency fast-axis flow carbon dioxide laser, which comprises a discharge electrode and a discharge glass tube with a hollow tube wall; the discharge electrode is arranged on the outer wall of the discharge glass tube; the discharge glass tube comprises a water inlet hole and a water outlet hole, and the water inlet hole and the water outlet hole are communicated with the hollow tube wall to form a cooling water channel; the water inlet hole is arranged at the exhaust end of the radio frequency fast-axis flow carbon dioxide laser, and the water outlet hole is arranged at the air inlet end of the radio frequency fast-axis flow carbon dioxide laser; a radio frequency power supply and a radio frequency adapter are connected with the discharge module and used for adjusting the temperature of the exhaust end of the radio frequency fast-axis flow carbon dioxide laser. The radio frequency adapter is arranged, so that the ten-thousand-watt radio frequency fast-axis flow carbon dioxide laser can reduce the temperature of the high-temperature gas discharged from the exhaust end of the discharge tube in a water cooling mode, the temperature of the air inlet end and the exhaust end of the discharge tube is maintained stable, the laser can obtain higher gain, and the output power of the laser is improved.

Description

Technical Field

[0001] This invention relates to the field of lasers, and more specifically, to a kilowatt-level radio frequency fast axial flow carbon dioxide laser. Background Technology

[0002] High-power radio frequency fast axial flow carbon dioxide lasers with a power of 10 kilowatts or more are used as extreme ultraviolet lithography sources and in particle acceleration experiments. Currently, most carbon dioxide lasers with a power of 10 kilowatts or more are maintained by a combination of fans and heat exchangers, using gas circulation to cool the temperature of the internal discharge region.

[0003] During laser operation, to ensure a sufficiently high laser gain, the temperatures at both the inlet and outlet of the discharge glass tube need to remain relatively stable. Since the gas mass flow rate provided by the fan in a carbon dioxide laser is already close to its limit, it is difficult to achieve temperature stability by further increasing the fan speed in a high-power carbon dioxide laser.

[0004] Therefore, existing cooling methods are insufficient to meet the demand for increasing laser output power by increasing the radio frequency electrical power deposition of carbon dioxide lasers. Summary of the Invention

[0005] The purpose of this invention is to provide a 10,000-watt-class radio frequency fast axial flow carbon dioxide laser, which can solve at least one of the aforementioned technical problems. The specific solution is as follows:

[0006] According to specific embodiments disclosed in this invention, a 10,000-watt-class radio frequency fast axial flow carbon dioxide laser is disclosed, comprising:

[0007] RF power supply;

[0008] A discharge module includes: a discharge electrode and a discharge glass tube with a hollow wall; the discharge electrode is disposed on the outer wall of the discharge glass tube; the discharge glass tube includes: a water inlet and a water outlet, the water inlet and the water outlet communicating with the hollow wall to form a cooling water channel; the water inlet is disposed at the exhaust end of the radio frequency fast axial flow carbon dioxide laser, and the water outlet is disposed at the air inlet end of the radio frequency fast axial flow carbon dioxide laser;

[0009] An RF adapter, connecting the RF power supply and the discharge module, is used to regulate the temperature at the exhaust end of the RF fast axial flow carbon dioxide laser.

[0010] Preferably, the discharge electrode comprises:

[0011] The first discharge electrode is connected to the ground wire;

[0012] The second discharge electrode includes multiple sub-discharge electrodes, which are sequentially connected by an insulating block.

[0013] Preferably, there are multiple radio frequency adapters;

[0014] Each of the aforementioned RF adapters is individually grounded;

[0015] Each of the radio frequency adapters is connected in series with the sub-discharge electrode and the radio frequency power supply, and multiple radio frequency adapters are connected in parallel with each other.

[0016] Preferably, the radio frequency adapter includes:

[0017] A first adjustable inductor is connected in series with the radio frequency power supply;

[0018] The second adjustable inductor is connected in parallel with the radio frequency power supply.

[0019] Preferably, the impedance Z of the equivalent circuit model of the discharge module satisfies the following relationship:

[0020]

[0021] Among them, R d Let j represent the imaginary part of the plasma resistance.

[0022] ω is the angular frequency of electrons in the gas medium of the discharge tube;

[0023] C0 is the capacitance of the discharge electrode, which is composed of the equivalent capacitances of various dielectrics connected in series.

[0024] Preferably, the capacitance C0 of the discharge electrode satisfies the following relationship:

[0025]

[0026] C i =ε i A / 4πkl i i = 1, 2, 3;

[0027] Where C1 represents the equivalent capacitance of the glass dielectric;

[0028] C2 represents the equivalent capacitance of air dielectric;

[0029] C3 represents the equivalent capacitance of the cooling water; k represents the electrostatic constant.

[0030] ε i and l i These represent the relative electrostatic constant and thickness of the corresponding medium, respectively.

[0031] Preferably, the first adjustable inductor L 串 It satisfies the following relationship:

[0032]

[0033] The second adjustable inductor L 并 It satisfies the following relationship:

[0034]

[0035] Among them, Z s The output impedance of the radio frequency power supply;

[0036] A represents the discharge area of ​​the discharge electrode.

[0037] Preferably, when the flow rate of the cooling water circuit is 20L / min, the temperature difference between the water inlet and the water outlet is 10±1℃, and the plasma temperature at the exhaust end is less than 220℃.

[0038] Preferably, the discharge electrode is arranged in a spiral or straight line on the outer wall of the discharge glass tube.

[0039] Preferably, the coolant used in the cooling water circuit is deionized water or a liquid with a conductivity of <10μS / cm.

[0040] Compared with the prior art, the solutions disclosed in this invention have at least the following beneficial effects:

[0041] This invention enables a 10,000-watt-level radio frequency fast axial flow carbon dioxide laser to reduce the temperature of the high-temperature gas exiting the discharge tube exhaust end through water cooling by setting an radio frequency adapter. This ensures that the temperature at the discharge tube inlet and outlet ends remains stable, allowing the laser to obtain a sufficiently high gain and improving the laser's output power. Attached Figure Description

[0042] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure of this invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0043] Figure 1 A schematic diagram of the overall structure of a 10,000-watt-level radio frequency fast axial flow carbon dioxide laser provided for an embodiment of the present invention;

[0044] Figure 2 for Figure 1 A sectional view;

[0045] Figure 3 The circuit schematic diagrams of multiple radio frequency adapters provided in the embodiments of the present invention are shown. Attached image description:

[0047] 1 Discharge module; 11 Discharge glass tube; 112 Air inlet; 113 Exhaust; 114 Water inlet; 115 Water outlet; 116 Cooling water channel; 12 Discharge electrode; 121 First discharge electrode; 122 Second discharge electrode.

[0048] 2. RF adapter; 21. Insulating block; 22. First adjustable inductor; 23. Second adjustable inductor.

[0049] 3. Radio frequency power supply. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, a 10,000-watt-level radio frequency fast axial flow carbon dioxide laser disclosed in this invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments disclosed in this invention, and not all of them. Based on the embodiments disclosed in this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the application. The singular forms “a,” “said,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0052] It should be understood that the term "and / or" used in this article 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 existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0053] It should be understood that although the terms first, second, third, etc., may be used to describe embodiments of this application, these terms should not be used in isolation. These terms are only used to distinguish between different terms. For example, first may also be referred to as second without departing from the scope of embodiments of this application, and similarly, second may also be referred to as first.

[0054] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0055] In the DC discharge process of a kilowatt-class low-power DC carbon dioxide laser, the electric field direction is parallel to the flow field direction, meaning the water cooling path is not in the discharge circuit and does not affect the DC glow discharge. Therefore, a three-layer glass tube structure can be used for kilowatt-class low-power DC carbon dioxide lasers, utilizing the middle layer of the glass tube for water cooling to maintain the temperature of the discharge region.

[0056] Unlike kilowatt-level low-power DC CO2 lasers, in 10-kilowatt-level and above high-power RF fast axial CO2 lasers, since the electric field direction is perpendicular to the flow field direction, and the discharge electrode surrounds the discharge glass tube, if cooling is still performed by passing cooling water through the glass tube, it will cause electromagnetic induction of the cooling water, resulting in a mismatch with the RF power supply and the inability to inject RF power.

[0057] Therefore, the present invention provides a 10,000-watt-level radio frequency fast axial flow carbon dioxide laser. By setting up a radio frequency adapter, the 10,000-watt-level radio frequency fast axial flow carbon dioxide laser can reduce the temperature of the high-temperature gas coming out of the exhaust end of the discharge tube through water cooling, thereby ensuring that the temperature of the gas inlet and exhaust ends of the discharge tube remains stable, so that the laser can obtain a sufficiently high gain and improve the output power of the laser.

[0058] The following is in conjunction with the appendix Figure 1-3 Detailed description of optional embodiments of the present invention.

[0059] like Figure 1-2 As shown, a 10,000-watt-class radio frequency fast axial flow carbon dioxide laser includes:

[0060] The discharge module 1 further includes: a discharge glass tube 11 with a hollow tube wall and a pair of discharge electrodes 12.

[0061] The discharge electrode 12 is disposed on the outer wall of the discharge glass tube 11, and an air medium layer exists between the discharge electrode 12 and the discharge glass tube 11.

[0062] Radio frequency (RF) power supply, used to provide power to the RF fast axial flow carbon dioxide laser.

[0063] RF adapter 2 connects to RF power supply and discharge module 1, and is used to regulate the temperature of exhaust end 113 of RF fast axial flow carbon dioxide laser.

[0064] In one embodiment of the present invention, the discharge electrode 12 is arranged in a spiral or straight shape on the outer wall of the discharge glass tube 11. The two ends of the discharge electrode 12 are sleeved on the tube wall of the discharge glass tube 11 by a fixing assembly.

[0065] Furthermore, the discharge glass tube 11 includes: a water inlet 114 and a water outlet 115.

[0066] The water inlet 114 and water outlet 115 are connected to the hollow portion of the discharge glass tube 11 to form a cooling water channel 116. The water inlet 114 is located near the exhaust end of the RF fast axial flow carbon dioxide laser, and the water outlet 115 is located near the gas inlet end of the RF fast axial flow carbon dioxide laser. During operation, by adding a cooling channel to the gas flow field circulation, the temperature of the high-temperature gas exiting from the exhaust end can be reduced, and the cooled gas can be recirculated back to the gas inlet end, thereby maintaining a stable temperature at the gas inlet end inside the discharge glass tube.

[0067] In this embodiment of the invention, in order to ensure that the cooling liquid on the inner wall of the discharge glass tube does not affect the discharge state during operation, the cooling liquid is selected as deionized water or other liquids with a specific conductivity of <10μS / cm.

[0068] In the operation of a 10,000-watt radio frequency carbon dioxide laser employing a gas flow circulation cooling mode, the temperature at the exhaust end gradually increases as the radio frequency power is deposited, eventually stabilizing within a stable temperature range. To ensure laser gain, the temperature at the exhaust end needs to be maintained below 220°C.

[0069] At this point, the temperature gradient between the exhaust end and the intake end can be roughly expressed as:

[0070]

[0071] Among them, P 注入 For the deposition of electrical power in the discharge region;

[0072] C 气体 v is the specific heat capacity of the gas. 气体 Let ρ be the gas flow velocity. 气体 The density of the gas;

[0073] S is the diameter of the discharge glass tube.

[0074] It can be seen that to increase the deposition of electrical power while maintaining a constant temperature gradient, it is necessary to increase the mass flow rate of the gas per unit time in the discharge region, i.e., to increase the fan speed. Currently, the flow field wind speed in high-power carbon dioxide lasers is already close to the speed of sound. If the wind speed reaches supersonic speed or above, phenomena such as shock waves and sound barriers will occur, severely affecting the discharge process. Furthermore, further increasing the fan speed in high-power carbon dioxide lasers is already very difficult in current industrial applications.

[0075] Therefore, when the cooling water circuit of this embodiment is used to reduce the temperature at the exhaust end, the power p of the cooling water circuit is... 水 The temperature gradient between the exhaust end and the intake end can be expressed as:

[0076] p 水 =C 水 G 水 ΔT 水

[0077]

[0078] Among them, C 水 This refers to the specific heat capacity of the coolant.

[0079] G 水 This refers to the mass flow rate of the coolant.

[0080] ΔT 水 This refers to the temperature difference between the water outlet and the water inlet.

[0081] It can be seen from the formula that at a gas flow velocity v 气体 Under certain conditions, as the electric power P in the discharge region is deposited... 注入 In this embodiment, the discharge module can maintain the temperature stability of the intake and exhaust ends to a certain extent, keeping the temperature at the exhaust end below 220°C.

[0082] For a standard industrial water chiller with a flow rate of 20L / min, when the injected electric power is increased to 14kW, the temperature difference between the outlet and inlet in this embodiment can be maintained at around 10℃.

[0083] As an alternative implementation, the discharge glass tube with hollow walls can be replaced by a discharge glass tube and a sealed glass tube nested outside the discharge glass tube. The space formed between the two glass tubes serves as a cooling water passage, with inlet and outlet holes located on the outer glass tube wall.

[0084] In embodiments of the present invention, the cooling water circuit causes temperature changes in the discharge glass tube, and the introduction of coolant medium parameters causes changes in the impedance of the discharge module. Furthermore, the spatial distribution of the discharge module temperature varies, resulting in different spatial distributions of the load impedance.

[0085] Therefore, in order to ensure that each area of ​​the discharge module achieves maximum power deposition after the addition of the cooling water circuit, this embodiment designs multiple RF adapters to match different temperature regions.

[0086] like Figure 3 As shown, in this embodiment, the first discharge electrode 121 is grounded, and the second discharge electrode 122 is divided into three sub-discharge electrodes. Each sub-discharge electrode is connected by an insulating block 21. Each sub-discharge electrode has a separate radio frequency adapter 2 to solve the problem of mismatch between the cooling water electromagnetic induction and the radio frequency power supply 3, which prevents the injection of radio frequency power.

[0087] Specifically, each RF adapter 2 is grounded separately, each RF adapter 2 is connected in series with the sub-discharge electrode and the RF power supply 3 respectively, and the three RF adapters 2 are connected in parallel with each other.

[0088] Each RF adapter includes:

[0089] The first adjustable inductor 22 is connected in series with the radio frequency power supply 3;

[0090] The second adjustable inductor 23 is connected in parallel with the radio frequency power supply 3.

[0091] Given the discharge current I(t) during gas discharge, it can be expressed as:

[0092]

[0093] Where m, e, T, and v(T) represent the electron mass, charge, temperature, and collision frequency, respectively.

[0094] n(T), A, U, and d represent the electron density, the discharge area of ​​the electrode, the voltage amplitude, and the discharge distance, respectively.

[0095] Therefore, the expression for the impedance of the equivalent circuit model of the discharge module can be obtained:

[0096] Z = R d +iX d =md[v(T)+iω] / n(T)e 2 A

[0097] R d =mdv(T) / n(T)e 2 A

[0098] X d =mdω / n(T)e 2 A

[0099] Among them, R dFor plasma resistance; X d For reactance;

[0100] ω is the angular frequency of electrons in the gas medium of the discharge tube;

[0101] During discharge, the discharge module is represented by the plasma resistor and the capacitance C0 of the discharge electrode connected in series, such as... Figure 3 As shown, the capacitance C0 of the discharge electrode is composed of the equivalent capacitances C1, C2, and C3 of the quartz glass dielectric, air dielectric, and deionized water dielectric connected in series. The expression for C0 is:

[0102]

[0103] C i =ε i A / 4πkl i i = 1, 2, 3;

[0104] Where C1 represents the equivalent capacitance of the glass dielectric;

[0105] C2 represents the equivalent capacitance of air dielectric;

[0106] C3 represents the equivalent capacitance of the cooling water; k represents the electrostatic constant.

[0107] ε i and l i These represent the relative electrostatic constant and thickness of the corresponding medium, respectively.

[0108] The plasma resistance can be determined by the ideal gas equation P = Nk in the discharge tube. B T(N is the total number of gas molecules, k) B (where is the Boltzmann constant and T is the thermodynamic temperature), and the threshold condition for the mixed gas to maintain self-sustaining discharge is E / N ≥ 3.5 x 10⁻⁶. - 16 Vcm 2 The plasma resistance R was calculated. d .

[0109] Therefore, the expression for the impedance of the equivalent circuit model of the discharge structure of a 10,000-watt RF-excited axial fast-flow carbon dioxide laser can be obtained as follows:

[0110]

[0111] Where P = Nk B T;P L For injected power

[0112] d is the discharge distance, and T is the thermodynamic temperature.

[0113] ω is the angular frequency of the radio frequency electric field;

[0114] k represents the electrostatic constant;

[0115] l1, l2, and l3 represent the thicknesses of the quartz glass medium, the air medium, and the deionized water medium, respectively.

[0116] ε1, ε2, and ε3 represent the relative electrostatic constants of the quartz glass medium, the air medium, and the deionized water medium, respectively.

[0117] According to the impedance matching theory of radio frequency circuits, when the load impedance and the radio frequency power supply impedance Z s (Z s When the impedance is 50Ω, the circuit power transfer efficiency is the highest. A system of equations can be established by combining the series and parallel connections of the first and second adjustable inductors:

[0118]

[0119] Among them, L 串 It is the first adjustable inductor;

[0120] L 并 This is the second adjustable inductor;

[0121] Z s The output impedance of the radio frequency power supply is denoted as .

[0122] When Z s When the Ω is 50Ω, the following can be obtained by solving the equation:

[0123] First adjustable inductor L 串 The numerical expression for is:

[0124]

[0125] Second adjustable inductor L 并 The numerical expression for is:

[0126]

[0127] Where k represents the electrostatic constant;

[0128] A represents the discharge area of ​​the discharge electrode.

[0129] Therefore, based on the temperature on the three discharge electrodes and the parameters of the discharge module, the values ​​of the first and second adjustable inductors on each RF adapter can be calculated.

[0130] In this embodiment, the influence of coolant on RF impedance matching is fully considered during the acquisition of RF adapter parameters. This allows the water cooling system to maintain stable temperatures at the inlet and outlet of the discharge tube of the 10,000-watt RF fast axial flow carbon dioxide laser, reducing the temperature gradient between the downdraft and updraft inside the discharge tube, ensuring maximum power deposition in the discharge area, and improving the output power of the laser.

[0131] In this embodiment, the adjustable inductor refers to the static matching of the entire impedance loop after the discharge operation has stabilized. This matching method is more suitable for fixed loads. It is not intended to adjust the impedance of the entire loop using an adjustable capacitor during laser operation to obtain a higher dynamic matching range. Dynamic matching, on the other hand, is suitable for situations where the load changes frequently.

[0132] In summary, when the flow rate of the connected water chiller is 20L / min, by using the RF adapter of the present invention, the temperature difference between the water inlet and the water outlet of the 10,000-watt RF fast axial flow carbon dioxide laser of the present invention can be 10±1℃, and the plasma temperature at the exhaust end can be less than 220℃, which meets the requirements of industrial development for increasing the power of carbon dioxide lasers.

[0133] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0134] The above embodiments are only used to illustrate the technical solutions disclosed in this invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments disclosed in this invention.

Claims

1. A multi-kilowatt radio frequency fast-axis flow carbon dioxide laser, characterized by, The application relates to a radio frequency fast axial flow carbon dioxide laser, which comprises the following parts: a radio frequency power supply; a discharge module, which comprises a discharge electrode and a discharge glass tube with a hollow tube wall; the discharge electrode is arranged on the outer wall of the discharge glass tube; the discharge glass tube comprises a water inlet hole and a water outlet hole, which form a cooling water channel in communication with the hollow tube wall; the water inlet hole is arranged at the exhaust end of the radio frequency fast axial flow carbon dioxide laser, and the water outlet hole is arranged at the air inlet end of the radio frequency fast axial flow carbon dioxide laser; a radio frequency adapter, which is connected with the radio frequency power supply and the discharge module and is used for adjusting the temperature of the exhaust end of the radio frequency fast axial flow carbon dioxide laser; the radio frequency adapter comprises: a first adjustable inductor, which is connected in series with the radio frequency power supply; a second adjustable inductor, which is connected in parallel with the radio frequency power supply.

2. The radio frequency fast-axis flowing carbon dioxide laser of claim 1, wherein, the discharge electrode comprises: a first discharge electrode, which is connected with a ground wire; a second discharge electrode, which comprises a plurality of sub-discharge electrodes connected in sequence through insulating blocks.

3. The radio frequency fast-axis flowing carbon dioxide laser of claim 2, wherein, the radio frequency adapter is multiple; each radio frequency adapter is independently grounded; each radio frequency adapter is connected in series with the sub-discharge electrode and the radio frequency power supply, and the multiple radio frequency adapters are connected in parallel with each other.

4. The radio frequency fast-axis flowing carbon dioxide laser of claim 1, wherein, The equivalent circuit model impedance Z of the discharge module satisfies the following relationship: where R d is the plasma resistance and j represents the imaginary part. omega is the angular frequency of electrons in the discharge tube gas medium; C0 is the capacitance of the discharge electrode connected in series with the equivalent capacitances of multiple media.

5. The radio frequency fast-axis flowing carbon dioxide laser of claim 4, wherein, The capacitance C0 of the discharge electrode satisfies the following relationship: C i = ε i A / 4πkl i , i = 1, 2, 3; wherein C1 represents the equivalent capacitance of the glass medium; C2 represents the equivalent capacitance of the air medium; C3 represents the equivalent capacitance of the cooling water; k represents the electrostatic force constant; and A represents the discharge area of the discharge electrode.

6. The radio frequency fast axial flow carbon dioxide laser according to claim 1, wherein A represents the discharge area of the discharge electrode; k represents the electrostatic force constant; l1, l2 and l3 respectively represent the thicknesses of the quartz glass medium, the air medium and the deionized water medium; and epsilon1, epsilon2 and epsilon3 respectively represent the relative electrostatic constants of the quartz glass medium, the air medium and the deionized water medium. When the flow rate of the cooling water channel is 20 L / min, the temperature difference between the water inlet hole and the water outlet hole is 10+ / -1 DEG C, and the plasma temperature of the exhaust end is less than 220 DEG C. ε i and l i respectively represent the relative static permittivity and thickness of the corresponding medium; The discharge electrode is arranged in the form of a helix or a straight line on the outer wall of the discharge glass tube. The cooling liquid used in the cooling water channel is deionized water or a liquid with an electric conductivity less than 10 mu S / cm. said first adjustable inductance L 串 satisfies the following relation: said second adjustable inductance L 并 satisfies the following relationship: wherein Z s is the output impedance of the RF power source; ​ ​ ​ ​ 7. The radio frequency fast-axis flowing carbon dioxide laser of claim 1, wherein, ​ 8. The radio frequency fast-axis flowing carbon dioxide laser of claim 1, wherein, ​ 9. The radio frequency fast-axis flowing carbon dioxide laser of claim 1, wherein, ​

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