RU2557325C2 - Discharge system for excimer laser (versions) - Google Patents

Abstract

FIELD: physics, optics.

SUBSTANCE: invention relates to laser engineering. The discharge system of an excimer laser includes a space discharge area (4) in a laser chamber (1) between first and second electrodes (2), (3), the longitudinal axes of which are parallel to each other; each preionisation unit (5) comprises a system for generating uniform complete creeping discharge on the surface of an extended dielectric plate (6), having an arched shape in the cross-section. The arched dielectric plate (6) can be in the form of a dielectric tube.

EFFECT: enabling laser energy and power increase.

21 cl, 13 dwg

Description

FIELD OF TECHNOLOGY.

The invention relates to quantum electronics, in particular to repetitively pulsed excimer lasers with UV preionisation by a sliding discharge, and can be used in the design and manufacture of excimer lasers and laser systems with high average radiation power.

BACKGROUND OF THE INVENTION

In high-power excimer lasers, the active medium is excited by a periodically pulsed volume discharge of high (2.5-5 atm) pressure in mixtures of inert gases (Ne, He, Xe, Kr, Ar) with halogen-containing molecules F ₂ , HCl at high ~ 1 MW / cm ³ pump power density. Such a discharge is fundamentally unstable, and the storage time by a volume discharge of a uniform shape usually does not exceed several tens of nanoseconds. Moreover, ensuring the optimal level of preionization of the active medium, which is subject to a number of changes during long-term continuous operation, is one of the main factors determining the achievement of high output characteristics of excimer lasers. In addition, the configuration of the UV preionization unit largely determines the geometry of the laser discharge system and, accordingly, the pumping conditions of the active medium.

In accordance with the needs of modern high-performance technologies using excimer lasers, their power is constantly increasing. However, an increase in the energy and average radiation power of gas-discharge excimer lasers has fundamental physical limitations, which, when the optimum values of the generation energy and pulse repetition rate are exceeded, cause a decrease in the laser efficiency, a decrease in the reliability and stability of its operation, and, ultimately, an increase in the cost of operating the laser.

All this determines the relevance of finding solutions to optimize the design and method of operation of excimer lasers, increase their power and stability, reduce the cost of generating lasing energy.

A known excimer laser discharge system [1], in which UV preionization is carried out by corona discharges ignited on the side of the high-voltage electrode. When used in an excimer laser, the discharge system makes it possible to efficiently obtain the generation energy at a high pulse repetition rate. The disadvantage of this device is the low level of preionization, limiting the possibility of increasing the aperture of the main discharge, increasing the generation energy and average laser power.

The discharge system of an excimer laser with UV preionization, emitted by radiation from two rows of sparks, automatically ignited when charging pulsed capacitors to the side of the high-voltage electrode located on the side of the wall of the laser chamber, is deprived of this drawback [2]. This system ensured the achievement of a high (600 W) average power of laser UV radiation in an excimer KrF laser. The disadvantage of an electrode system with a UV preionizer in the form of rows of separate spark gaps is the spatial heterogeneity of the preionization along the length of the electrodes, which reduces the laser efficiency and its complexity due to the need to seal dozens of current leads of the preionizer. In addition, spark gaps cause an increased entry into the gas of erosion products of the electrodes of the preionization unit, which reduces the lifetime of the laser gas mixture.

Partially these drawbacks are deprived of a discharge system of an excimer laser with preionization, which is carried out through a partially transparent electrode by UV radiation of a complete sliding discharge (SR) over a plane dielectric surface. plates [3]. This electrode system provides a high level and spatial uniformity of the preionization of the discharge zone between the high-voltage and grounded laser electrodes. The possibility of increasing the generation energy and average laser radiation power is achieved. At the same time, it is possible to reduce the energy pumped through the preionization unit several times, which, in turn, increases the lifetime of the gas mixture. When generating on XeCl, the average power of an excimer laser with this electrode system reached more than 1 kW. However, a partially transparent electrode with a preionization unit located on its reverse side has relatively large transverse dimensions, which increases the inductance of the discharge circuit. This factor limits the obtaining of highly efficient generation in excimer inert gas fluoride (KrF, ArF) lasers, for which a sharp dependence of the laser efficiency on the discharge circuit inductance is observed. In addition, partially transparent electrodes are complex and expensive to manufacture.

Partially these drawbacks are deprived of the excimer laser discharge system, containing an extended first electrode located on the side of the laser chamber wall located in the laser chamber, a second electrode, a volume discharge zone between the first and second electrodes, the longitudinal axes of which are parallel to each other, a preionization unit containing forming a uniform complete sliding discharge (CP) including a dielectric plate,

a firing electrode mounted on the front surface of the dielectric plate along it, and a long initiating electrode adjacent to the reverse side of the dielectric plate [4]. The CP formation system over the surface of an extended dielectric (sapphire) plate is located on the side of the second solid electrode. UV preionization from a sliding discharge provides a spatially uniform preionization of the discharge zone between the laser electrodes of optimally high intensity, with a relatively small energy input into the sliding discharge. All this makes it possible to obtain highly efficient laser generation with a high (up to 5 kHz) pulse repetition rate with a long lifetime of the gas mixture.

However, the CP formation system integrated into the laser gas flow circulation system has large transverse dimensions, which increases the cost of pumping gas. In addition, not all of the main discharge zone adjacent to the second electrode connected to the initiating electrode is optically connected to a part of the surface of the flat plate used to ignite the CP, which performs UV preionization. This makes it possible to obtain only a relatively narrow, £ 3 mm wide, discharge between the first and second electrodes and limits the possibility of obtaining high (over ~ 0.1 J / pulse) laser output energy when generated by ecimer molecules.

SUMMARY OF THE INVENTION

The objective of the invention is the creation of discharge systems that are integrated into the most powerful excimer lasers and laser systems of various configurations with the aim of highly efficiently increasing the generation energy and average power of laser UV radiation.

The technical result of the invention is to improve the discharge system of an excimer laser, increase the generation energy, average radiation power at high laser efficiency and reduce operating costs.

To solve these problems, an excimer laser discharge system is proposed that includes an extended first electrode located in the laser chamber mounted on the side of the laser chamber wall and a second electrode, a volume discharge zone between the first and second electrodes, the longitudinal axes of which are parallel to each other, at least , one preionization unit containing a system for generating a uniform complete sliding discharge (CP) between extended extended dielectric plates located on the surface with an igniting electrode and either an initiating electrode or an additional electrode connected to the initiating electrode, the extended dielectric plate has a curved cross section, the igniting electrode is mounted on the front surface of the curved dielectric plate along it, the extended initiating electrode is adjacent to the reverse surface

dielectric plate and at least adjacent to the initiating electrode, the extended portion of the reverse surface of the curved dielectric plate is cylindrical.

In embodiments of the invention, the CP forming system is mounted so that the generatrixes of the cylindrical surface of the curved dielectric plate are parallel to the longitudinal axes of the first and second electrodes.

In embodiments of the invention, the front and back sides of the curved dielectric plate are cylindrical.

In embodiments of the invention, at least a portion of the surface of the curved dielectric plate aligned with the surface of the initiating electrode is circularly cylindrical.

In embodiments of the invention, the curved dielectric plate is made in the form of an extended part of a cylindrical thin-walled dielectric tube enclosed between two longitudinal sections of the tube parallel to its longitudinal axis.

In embodiments of the invention, two identical preionization units are located on the sides of either the first solid electrode or the second solid electrode.

In embodiments of the invention, the front surface of the curved dielectric plate is convex.

In embodiments of the invention, either sapphire or ceramic, in particular Al ₂ O _{3, is} used as the material of the curved dielectric plate.

In embodiments of the invention, the initiating electrode is made either cooled by a gas stream or a liquid coolant.

In embodiments of the invention, each point of the discharge zone between the first and second electrodes is in the line of sight of at least a portion of the surface of the curved dielectric plate used to form the CP.

In embodiments of the invention, the front surface of the curved dielectric plate is concave.

In embodiments of the invention, a portion of the curved dielectric plate not used to form the CP is located on the back of either the first electrode or the second electrode.

In embodiments of the invention, the curved dielectric plate is made in the form of a cylindrical thin-walled dielectric tube with a longitudinal section.

In embodiments of the invention, the curved dielectric plate is made in the form of a cylindrical thin-walled dielectric tube with a longitudinal section, the initiating electrode is placed inside the dielectric tube, and an additional electrode is connected to the initiating electrode through a longitudinal section of the dielectric tube.

In embodiments of the invention, the CP forming system comprises, as a curved dielectric plate, a solid dielectric tube inside which is placed

the initiating electrode, while on the outer surface of the solid dielectric tube an additional electrode is placed.

It is preferable that the additional electrode is connected to the initiating electrode through the end face of the dielectric tube.

In embodiments of the invention, either an ignition electrode or an additional electrode is connected to either the first electrode or the second electrode.

In embodiments of the invention, an ignition electrode or an additional electrode is combined with either the first electrode or the second electrode.

In embodiments of the invention, either the first electrode or the second electrode is made partially transparent, having an extended niche on the back side, in which at least partially an extended preionization unit is placed, while in the preionization unit the CP formation system is made symmetrical with respect to a plane including itself along the longitudinal axis of the first and second electrodes, and contains two CP zones symmetrically located on both sides of the indicated plane.

In this case, it is preferable that a ceramic insulator with a p-shaped or U-shaped cross-section is placed at least partially in the extended niche, and the CP formation system is at least partially placed in the extended ceramic insulator.

In another aspect, the invention relates to an excimer laser discharge system including an extended first electrode located in the laser chamber mounted on the side of the laser chamber wall, a second electrode, a volume discharge zone between the first and second electrodes, the longitudinal axes of which are parallel to each other, and, at least one preionization unit, wherein each preionization unit contains a system for forming a uniform complete CP on the surface of a solid dielectric tube between extended ignitions a feeding electrode and an additional electrode mounted on the front surface of the dielectric tube along it, and inside the dielectric tube there is an extended initiating electrode adjacent to the reverse surface of the dielectric tube.

Preferably, the additional electrode is connected to the initiating electrode through the end face of the dielectric tube.

In embodiments of the invention, a firing electrode and an additional electrode are placed diametrically opposite on the front surface of a solid dielectric tube.

The above and other objects, aspects, features and advantages of the invention will become more apparent from the following description and claims.

The description is given in a form sufficient to understand the principles of the invention by specialists in the field of laser technology. A detailed description of the components of excimer gas-discharge lasers can be found in [1-3, 5].

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by the accompanying drawings, which are presented in a form sufficient to understand the principles of the invention and in no way limit the scope of the present invention.

Figure 1 - diagram of a discharge system with one block preionization.

Figure 2 is a diagram of a laser with a discharge system comprising two preionization units mounted on the sides of the second electrode.

Figure 3 is a diagram of a discharge system with two preionization units mounted on the sides of the first electrode.

Figure 4 is a diagram of a laser with a discharge system comprising two preionization units mounted on the sides of the first electrode.

5 is a diagram of a discharge system with preionization blocks, including a system for the formation of SR on a concave surface of the dielectric.

6 is a diagram of a laser with preionization radiation SR on the concave surface of the dielectric.

7 is a diagram of a discharge system with preionization units, including a system for the formation of SR on the surface of a dielectric tube with a longitudinal section.

Fig. 8 is a diagram of a laser with preionization units including a CP forming system along the surface of a dielectric tube with a longitudinal section.

Fig.9 is a diagram of a discharge system with two blocks preionization, including a system for the formation of SR on the surface of a solid dielectric tube.

Figure 10 is a diagram of a discharge system with preionization through a partially transparent first electrode.

11 is a diagram of a laser with preionization through a partially transparent first electrode.

12 is a diagram of a discharge system with a partially transparent first electrode and a CP forming system over the surface of a solid dielectric tube.

13 is a diagram of a laser with a partially transparent first electrode and a CP forming system over the surface of a solid dielectric tube.

In the drawings, matching device elements are denoted by the same reference numbers.

MODES FOR CARRYING OUT THE INVENTION

In accordance with the invention, the excimer laser discharge system comprises an extended first electrode 2 located in the laser chamber 1, mounted on the side of the laser chamber wall 1, a second electrode 3, a volume discharge zone 4 between the first and second electrodes 2, 3, the longitudinal axes of which are perpendicular to the plane FIG. 1 are parallel to each other. The discharge system also comprises a preionization unit 5 with a uniform complete sliding discharge (CP) formation system. The CP formation system includes an extended dielectric plate 6, igniting (as we call it) an electrode 7, mounted on the front surface 8 of the dielectric plate 6 along it, a long initiating (as we call it) electrode 9, adjacent to the reverse side 10 of the dielectric plate 6 and an extended additional (as we call it) electrode 14 located on the surface of the dielectric plate, which is either connected or combined (Fig. 1) with the initiating electrode 9. Necessary for a highly efficient For highly stable laser operation, uniformity of the completed CP is achieved when the interelectrode distance l of the CP formation system on the surface of the dielectric plate (6) between the ignition electrode (7) and the additional electrode (14) is not less than a certain characteristic value: l≥1.5 cm. the dielectric plate 6 has a curved cross section and at least a portion of the reverse surface 10 of the dielectric plate 6 adjacent to the extended initiating electrode 9 is cylindrical.

The excimer laser discharge system also contains a set of capacitors 12 connected to the first and second electrodes 2, 3, and a switching power supply 11 connected to the capacitors 12 and intended for their pulse charging to a breakdown voltage providing gas discharge between the first and second electrodes 2, 3 for exciting a laser gas mixture and generating a laser beam using a resonator (not shown). It is preferable that the switching power supply 11 is connected to the preionization unit 5 through additional capacitors 13 designed to provide automatic preionization when they are pulsed charging through the CP of the preionization unit 5.

The use of a curved dielectric plate in a complete sliding discharge formation system ensures the compactness of the laser discharge system, which leads to a decrease in the discharge circuit inductance and the possibility of a highly efficient increase in the generation energy, as well as

increasing the pulse repetition rate and increasing the average laser radiation power. The execution of at least a portion of the dielectric plate adjacent to the initiating electrode is cylindrical provides the relative ease of manufacture of the curved dielectric plate 6 and simplifies the combination of its reverse surface 10 with the surface of the extended initiating electrode 9, which is necessary for high uniformity of the CP.

In preferred embodiments of the invention, the CP forming system is installed so that the generatrices of the cylindrical surface 10 of the curved dielectric plate 6 are parallel to the longitudinal axes of the first and second electrodes 2, 3. The CP zone is parallel to the volume discharge zone 4. This ensures a uniform level of preionization along the entire length zones of volume discharge 4 and, accordingly, its high uniformity and resistance to acoustic disturbances in the regime with a high pulse repetition rate.

In the embodiment of the invention (FIG. 1), the preionization unit 5 is installed near the second electrode 3. Moreover, in accordance with one embodiment of the invention, the initiating electrode 9 of the CP formation system is connected to the second electrode 3 of the laser. This ensures the compactness of the device, reduces the inductance of the discharge circuit of the laser, increasing its efficiency.

In embodiments of the invention (Fig 1), the curved dielectric plate 6 is made in the form of an extended part of a cylindrical thin-walled dielectric tube enclosed between two longitudinal sections of the tube parallel to its longitudinal axis. This simplifies the manufacture of a curved dielectric plate 6.

In the embodiments of the invention (FIG. 1), the front 8 and back 10 sides of the curved dielectric plate 6 are circularly cylindrical. This provides a further simplification of the manufacture of a curved dielectric plate 6 when using a round-cylindrical dielectric tube as a blank.

To increase the generation energy and laser power in embodiments of the invention (FIGS. 2-9), the device comprises two identical preionization units 5 located on the sides of a solid either the first electrode 2 or the second electrode 3.

The features and advantages of the discharge system are more clearly illustrated when it is considered as part of an excimer laser. A gas-discharge excimer laser or a molecular fluorine laser, the cross section of which is shown in FIG. 2, contains a laser chamber 1 filled with a gas mixture. In the example embodiment of the invention (FIG. 2), the laser chamber 1 is made on the basis of a ceramic pipe, in which are located spaced apart from each other extended first electrode 2, located on the side of the wall of the laser chamber 1, and the second electrode 3.

Two identical preionization blocks 5 are located on the sides of the second electrode 3, made solid, which ensures the relative simplicity of the electrode, its high reliability and long life.

As a rule, the placement of CP formation systems near the second electrode 3 allows minimizing the inductance of the discharge circuit, which increases the efficiency of a high-energy excimer laser.

In each preionization unit 5, a complete CP is formed on the surface of the curved dielectric plate 6 between the ignition electrode 7 and the additional electrode 14. In this case, only the charging current of the capacitance of the part of the dielectric plate on which the CP is ignited is closed to the initiating electrode 9. In this regard, the extended massive initiating electrode 9 can be made of relatively cheap material, preferably with high thermal conductivity, for example, from A1. The additional electrode 14, to which the main current of the completed CP is closed, is made of erosion-resistant metal, for example, Ni, Cu-W, etc. Therefore, in embodiments of the invention, the additional electrode 14 of the CP formation system is aligned with the second laser electrode 3 (FIG. .2), either with the first electrode 2. In embodiments of the invention, the additional electrode 14 is connected to the second electrode 3, or with the first electrode 2. In preferred embodiments of the invention, the additional electrode 14 is connected to the initiating electrode 9 (Fig. 2). All this simplifies the electrical circuit of the CP formation system.

Outside the laser chamber 1, along it is a set of capacitors 12 connected to the first and second electrodes 2, 3 through busbars connected to the plates of the capacitors, electrical inputs 15, 16 of the laser chamber 1 and gas-permeable return conductors 17 located in the laser chamber 1 on both sides from the electrodes 2, 3. A pulse power supply 11 is connected to the capacitors 12. Also, the pulse power supply 11 is connected to the preionization unit 5 through additional electrical inputs 18 of the laser chamber 1 and gas-permeable additional body reverse conductors 19.

To update the gas in the zone of volume discharge 4 between the next discharge pulses in the laser chamber 1 is placed a gas circulation system containing

a diametrical fan 20, water-cooled tubes 21 of the heat exchanger, two extended spoilers 22 made in the ceramic embodiment of the invention, and extended guide vanes 23 for forming a gas flow (FIG. 2).

To generate a laser beam, a resonator is placed outside the laser chamber 1 (not shown for simplicity). The laser chamber may also contain a filter (not shown), in particular, electrostatic for cleaning the laser gas mixture from the erosion products of the elements of the laser chamber.

In embodiments of the invention (FIG. 1, FIG. 2), the front surface 8 of the curved dielectric plate 6 is convex. In contrast to the use of a flat dielectric plate known from [4], it is possible to integrate a highly efficient preionization unit 5 into the gas circulation system in such a way that the ignition and additional electrodes 7, 14 of the CP formation system do not prevent the formation of a high-speed gas flow in the zone of volume discharge 4.

In addition, in contrast to the discharge system with a flat dielectric plate, known from [4], for the formation of superlattices, the dark areas of the zone of volume discharge 4 near the second electrode 3 are eliminated. To realize the possibility of highly efficiently increasing the laser generation energy in the variants of the invention, each point of the zone of volume discharge 4 is in the line of sight of at least a portion of the discharge gap on the surface of the curved dielectric plate 6 used to form the SR. For this, the curved dielectric plates 6 of the two preionization units 5 must be installed so that the tangent to the surface of the first second electrode 3, perpendicular to the plane including the longitudinal axes of the first and second electrodes 2, 3, touches or intersects a part of the surface of each curved dielectric plate 6 used to ignite the CP. The high uniform level of preionization of the volume discharge zone 4, provided by the UV radiation of two superlattices, improves the uniformity and stability of the volume discharge, improves the stability of the output characteristics of the laser, and also increases the aperture of the laser beam, the generation energy, and the average laser radiation power.

The implementation of an extended dielectric plate curved in cross section, in particular, with a convex front surface allows you to remove the electrodes 7, 9, 14 of the systems of formation of CP from the zone of volume discharge 4 (Figure 2). This minimizes the distortions introduced by the preionization units 5 into the distribution of the electric field in the zone of the volume discharge 4, ensuring the uniformity of the volume discharge and the stability of its uniform shape to acoustic disturbances in the regime with a high pulse repetition rate. As a result, high stability of laser radiation energy from pulse to pulse and high quality of the laser beam are achieved.

For excimer lasers, the gas filling the laser chamber at a characteristic pressure in the range from 2.5 to 5 atm is a mixture of inert gases with halogen donors. In this regard, in embodiments of the invention, as the material of the curved dielectric plate 6 of each preionization unit 5, erosion-resistant and halogen-resistant dielectrics are preferably used: either sapphire or ceramics, in particular Al ₂ O ₃ , which provide a long lifetime of the dielectric plate in the preionization unit as well as the long lifetime of the laser gas mixture containing extremely chemically active components of F ₂ or HCl.

In the embodiment of the invention (FIG. 2), the initiating electrode 9 and the curved dielectric plate 6 adjacent to it, heated by CP, are cooled, at least in part, by heat transfer from the massive metal guide vane 23, which in turn is cooled by a gas stream circulating in the laser camera 1.

In embodiments of the invention, the initiating electrode 9 may be a cooled liquid coolant. For this, the initiating electrode may either have a channel for circulation of the coolant.

In embodiments of the invention, the initiating electrode 9 may be a cooled portion of the gas stream circulating in the laser chamber 1, having fins or pins of the radiator on the rear side of the initiating electrode 9.

The possibilities of achieving the maximum power of laser UV radiation in lasers and laser systems using laser chambers made on the basis of a ceramic tube are considered in more detail in [6].

In the embodiments of the invention illustrated in FIG. 3, two identical preionization units 5 are located on the sides of the first electrode 2. As a rule, this arrangement of CP forming systems simplifies the conductor system in the laser chamber 1.

In the embodiments of the invention (FIG. 3), in each preionization unit 5, an additional electrode 14 is installed on the back side 10 of the curved dielectric plate 6. Installing an additional electrode 14 on the back side 10 of the curved dielectric plate 6 at a small distance from its edge can further reduce the transverse size of the system the formation of a homogeneous SR. Due to this, the compactness of the discharge system and its low inductance are achieved, which increases the efficiency of a high-energy wide-aperture excimer laser.

In embodiments of the invention, the additional electrode 14 is combined with the initiating electrode 9, which in some cases simplifies the formation of a superlattice and the discharge system of the laser as a whole. For the same purpose, in embodiments of the invention, the ignition electrode 7 is aligned with the first electrode 2 (Figure 3).

The discharge system (Figure 3), made in accordance with the present invention, is applicable to high-power excimer lasers of various designs, including the laser design shown in Figure 2.

To illustrate, FIG. 4 shows a discharge system made in accordance with an embodiment of the present invention with respect to a high-power excimer laser with a design different from that previously discussed. For this embodiment of the invention, the laser chamber 1, made predominantly metal, contains extended ceramic containers 24 mounted near the first electrode 2. The end parts of each ceramic container 24 are hermetically attached to the ends of the laser chamber 1. In the ceramic containers 24 there are capacitors 12 connected inductively to the first and to the second electrodes 2, 3 through current leads 15, 16 and gas-permeable return current conductors 17. From the side of the first electrode 2 in the metal wall of the laser chamber 1 sealed high-voltage current leads 25 are installed, each of which is equipped with a ceramic insulator 26. Inside the laser chamber 1, on both sides of the ceramic containers 24 there are extended grounded conductors 27 connected to the metal wall of the laser chamber 1. In this case, the power supply 11 is connected inductively to the capacitors 12 through high-voltage current leads 25 and grounded current leads 27, as well as through high-voltage and grounded current leads 15, 16 of each ceramic container 24. Such a low-inductance connection Failure of the power source 11 to the capacitors 12 provides high values of the rate of rise of the electric field and the magnitude of the electric field in the discharge region 4 at the stage of breakdown. This improves the uniformity of the volumetric discharge of the laser and increases the stability of the uniform shape of the discharge to acoustic disturbances arising in the laser chamber at a high pulse repetition rate. The result is an increase in laser efficiency.

On both sides of the first solid electrode 2, two identical preionization units 5 are installed, each of which contains a CP formation system on the surface of a curved dielectric plate 6, made in the form of an extended part of a round-cylindrical thin-walled tube enclosed between its two longitudinal sections. Moreover, in each preionization unit 5, the ignition electrode 7 of the CP formation system mounted on the convex front surface of the curved dielectric plate 6 is connected to the first electrode 2, and the additional electrode 14 is connected to the initiating electrode 9 adjacent to the back side of the curved dielectric plate 6.

For automatic preionization, which simplifies the operation of the laser, additional capacitors 13 are placed in ceramic containers 24, the capacitance of which is many times smaller than the capacitance of capacitors 12, and they occupy a small part of the volume of containers 24. Additional capacitors 13 are connected to the preionization unit 5, namely, they are connected to an additional electrode 14 SR formation systems through additional current leads 18.

In Fig. 4, each ceramic container 24 has the shape of a rectangular tube, which ensures the compactness of the ceramic containers 24 with a high degree of their filling with ceramic capacitors 12 used for high-power gas-discharge lasers. As a result, a small inductance of the discharge circuit and an increase in the laser efficiency are achieved.

In the embodiments of the invention illustrated in FIG. 4, in order to reduce the inductance of the discharge circuit, the capacitors 12 are as close as possible to the discharge region 4. In these embodiments of the invention, extended ceramic containers 24 are placed to the side of the discharge region 4, forming their surfaces facing the discharge zone 4, located upstream and downstream of the discharge region 4, gas flow guides or spoilers that significantly change the direction of the gas flow when passing the discharge region 4. Such a geometry of the gas flow It can be effective because it eliminates the undesirable effect of separation of the gas stream from the second electrode 3 after the discharge region 4 passes through the stream. As described in more detail in [7], the use of ceramic containers with capacitors placed in them allows optimizing the geometry of the gas stream, discharge circuit, and excimer laser system in a wider range compared to known analogues. In addition, due to the placement of ceramic containers 24 on the sides of the discharge region 4, the capacitors 12 located therein can be as close as possible to the discharge region 4. Moreover, in the proposed invention, the wall of the container can be thinner than the wall of the ceramic discharge chamber of lasers known from [1] and used in the powerful VYPER double-beam laser system [8]. Accordingly, the inductance of the discharge circuit can be reduced. In addition, due to the use of preionization units 5, made in accordance with the present invention (Figure 4), the preionization level is higher than in analogues [1, 7] using corona discharge preionization. All this provides the possibility of increasing the stability of the output characteristics of the excimer laser, as well as the possibility of increasing the aperture of the volume discharge, energy and power of laser radiation at high laser efficiency.

In embodiments of the invention (Figure 5), in two identical preionization units 5 located on the sides of the first electrode 2, the front surface 8 of the curved dielectric plate 6 is concave. The curved dielectric plate 6 is preferably made in the form of an extended part of a circular cylindrical thin-walled tube, enclosed between two sections of the tube parallel to its longitudinal axis. Moreover, the reverse surface 10 of the curved dielectric plate 6 made of ceramic or sapphire is part of the outer surface of the round cylindrical tube, which facilitates the possibility of its processing with high accuracy during rotation of the workpiece tube. In addition, the extended surface of the initiating electrode adjacent to the reverse side of the dielectric plate 6 is concave round-cylindrical, which also facilitates the possibility of its precise machining with a milling tool. All this simplifies the manufacturing technology of the CP formation system with the exact combination of the surfaces of the curved dielectric plate 6 and the extended initiating electrode 9. As a result, highly efficient operation of the preionization unit 5 is achieved by ensuring high uniformity of the CP and efficient cooling of the curved dielectric plate 6 by means of the initiating electrode 9.

In accordance with embodiments of the invention, a portion of the curved dielectric plate that is not used to form a CP is located on the back of either the first electrode 2 (FIG. 5) or the second electrode 3 (FIG. 6), which also ensures compactness of the laser discharge circuit.

FIG. 6 illustrates an embodiment of the invention with two identical preionization units 5 mounted on the sides of the second electrode 3. In the embodiment of the invention (FIG. 6), the laser chamber 1 is predominantly ceramic. For automatic preionization, a switching power supply 11 is connected to each preionization unit 5 through additional capacitors 13, additional current leads 18 of the laser chamber, additional gas-permeable return current leads 19 and current leads 28 provided with ceramic insulators.

In these embodiments of the invention, along with the simplification of the manufacturing technology of the CP formation system, a small inductance of the discharge circuit is achieved, including by placing part of the curved dielectric plate 6 on the back side of either the first electrode 2 (Figure 5) or the second electrode 3 (Fig .6).

In the embodiments of the invention illustrated in FIG. 7, the discharge system comprises two identical CP formation systems 5 mounted on the side of the second electrode 3. In each of the two preionization units 5, the CP formation system is characterized by the following:

- curved dielectric plate 6 is made in the form of a cylindrical thin-walled dielectric tube with a longitudinal section 29,

- the initiating electrode 14 is placed inside the dielectric tube 6 and connected to the initiating electrode 9 through a longitudinal section 29 of the dielectric tube 6,

- an additional electrode 14 of each preionization unit 5 is connected to the second electrode 3.

Here, the section means that its transverse dimension is much smaller than the diameter of the tube and close in magnitude to the thickness of the thin-walled dielectric tube.

When the device is executed in the indicated form, an improvement in the compactness of the SL formation system and a decrease in the inductance of the discharge system are also achieved, which makes it possible to increase the efficiency of a wide-aperture high-energy excimer laser. The implementation of the curved dielectric plate 6 in the form of a ceramic tube with a longitudinal section 29, along with the compactness of the preionization unit, provides the relative simplicity of the manufacturing technology of the formation system of the CP. The implementation of the tube thin-walled, that is, with a value of its thickness not exceeding a certain upper boundary, provides at the stage of ignition of the SR high electric field strength on the surface discharge gap, necessary to obtain high uniformity of the completed SR. The characteristic dimensions of the thin-walled tube 6 may be as follows: diameter 15 mm, thickness 1.3 mm.

In Fig. 8, illustrating a discharge system comprising a high-power high-energy excimer laser, identical preionization units 5 with curved dielectric plates 6 in the form of a tube with a longitudinal section are located on both sides of the first electrode 2 in the laser chamber 1 made on the basis of a ceramic tube. In this embodiment, the simplicity and compactness of the discharge circuit of the system for the formation of superlattices is achieved by connecting or combining the ignition electrode 7 with the first laser electrode 2 and connecting the additional electrode 14 with additional capacitors 13 through additional current leads 18 installed in the wall of the laser chamber 1 along its length (without the use of additional gas-permeable return conductors 19, as in the schemes of Fig.2 and Fig.6).

In other embodiments of the invention, the CP formation system of each preionization unit 5 comprises, as a curved dielectric plate 6, an integral cylindrical thin-walled dielectric tube, inside which an initiating electrode 9 is placed, and an additional electrode 14 is placed on the outer surface of the whole dielectric tube (Fig. 9). In the embodiment of the invention (Fig. 9), two identical preionization units 5 are located on the sides of the second electrode 3. These embodiments of the invention, along with the compactness of the preionization units 5, make it possible to simplify the curved dielectric plate of the CP formation system even more. Moreover, in embodiments of the invention, an additional electrode, preferably, although not necessarily, is connected to the initiating electrode through the end of the dielectric tube, which increases the electric field in the plasma of the CP at the stage of its ignition and improves the uniformity of the completed CP.

These variants of the invention make it possible to minimize the size of the discharge system with preionization by UV radiation of the superlattice and to increase the generation energy and laser power when using simple and reliable solid laser electrodes, which generally simplifies the discharge system of the excimer laser.

A further increase in the generation energy and / or excimer laser power is possible when a partially transparent electrode is used in the discharge system.

In this regard, in embodiments of the invention, either the first electrode (Fig. 10-12) or the second electrode (Fig. 13) is partially transparent, the preionization unit 5 is placed on the back side of the partially transparent electrode, while the CP formation system is symmetrical about the plane 30, including the longitudinal axis 31, 32 of the first and second electrodes 2, 3, perpendicular to the plane of the drawing (Figure 10). Moreover, the CP formation system contains two CP zones symmetrically located on both sides of the indicated plane 30. Each CP zone is located on the surface of a curved dielectric plate between the ignition electrode 7 and the additional electrode 14 or the initiating electrode 9 in the absence of an additional electrode 14. With the exception of two end parts of an extended curved dielectric plate 6, two zones of the CP occupy the entire front surface 8 of the curved dielectric plate 6, located on the sides of the igniting electric Electrode 7. In embodiments of the invention, a part of the front surface of a partially transparent electrode adjacent to the zone of volume discharge 4 is made thin-walled, profiled on the front side and made with slotted holes 33.

In the embodiment of the invention (Figure 10), the curved dielectric plate 6 is made in the form of an extended part of a cylindrical thin-walled dielectric tube enclosed between two longitudinal sections of the tube parallel to its longitudinal axis. The front surface of the curved dielectric plate 6 is convex and faces the partially transparent first electrode 2. A part of the surface of the extended initiating electrode 9 is adjacent to the back side of the curved dielectric plate 6, and the other part of the surface of the initiating electrode 9 is connected or combined with the additional electrode 14. the electrode 7 of the CP formation system is mounted on a convex cylindrical surface of a curved dielectric plate 6 and is connected to a partially transparent first Electrode 2 wireways 34 mounted along the length of the ignitor 7 that act as anchorages ignitor 7 and practically does not decrease, due to the high transparency level preionization discharge area 4.

The partially transparent electrode 2 (Fig. 10) has an extended niche 35 on the back side, in which, at least partially, an extended preionization unit 5 is placed. This ensures the compactness of the electrode assembly and increases the efficiency of the preionization unit 5 by placing it in close proximity from discharge zone 4.

In embodiments of the invention, in an extended niche 35 of a partially transparent electrode 2 (FIG. 10), at least partially an extended ceramic insulator 36 is arranged with a π-shaped (FIG. 10) or p-shaped (not shown) cross-section. In this case, the preionization unit 5 is at least partially placed in an extended ceramic insulator 36 on the back side of the partially transparent electrode 2 (Figure 10). In these embodiments of the invention, the maximum compactness of the electrode assembly and the laser discharge system as a whole is achieved by eliminating parasitic breakdowns between the partially transparent electrode and the preionization unit using an extended ceramic insulator 36. To eliminate spurious breakdowns between the current leads 16 and 18, they should preferably be located in different transverse sections of the discharge system or in other words in a checkerboard pattern when viewed from above. At the same time, π-shaped flaps of the extended ceramic insulator 36 prevent spurious breakdown from the current lead 18 to the edge of the partially transparent electrode 2 (Figure 10).

A discharge system made in accordance with the present invention is applicable to high-power excimer lasers of various designs. To illustrate, Fig. 11 shows a discharge system made in accordance with an embodiment of the present invention with respect to a high-power excimer laser, in which the laser chamber 1, made mainly of metal, contains extended ceramic containers 24 mounted near a partially transparent first electrode 2. In ceramic containers 24, the end parts of which are hermetically fixed to the ends of the laser chamber 1, are placed capacitors 12, connected inductively to the first and second electrodes 2, 3 cut current leads 15, 16, installed in this embodiment of the invention in ceramic containers 24, and through gas-permeable return conductors 17. In this case, the power source 11 is inductively connected to the capacitors 12 through the high-voltage current leads 25 of the laser chamber 1 equipped with ceramic insulators 26 and the ground conductors 27, and also through high-voltage and grounded current leads 15, 16 of each ceramic container 24.

Placed in ceramic containers 24, additional capacitors 13, providing automatic preionization, are connected to the preionization unit 5 through additional current leads 18 installed in the ceramic container 24 along their length.

The preionization unit 5 is partially placed in an extended niche 35 on the back side of the partially transparent first electrode 2 (Fig. 11). Moreover, the CP formation system is made symmetrical with respect to the plane, including the longitudinal axis of the first and second electrodes 2, 3, and includes two CP zones symmetrically located on both sides of the specified plane. The firing electrode 7 mounted on the convex cylindrical surface of the curved dielectric plate 6 is connected to the partially transparent first electrode 2 by conductors 34. The curved dielectric plate 6 may be made in the form of a part of a circular cylindrical thin-walled dielectric tube with a longitudinal section. When this initiating electrode 9 is placed inside the dielectric tube, and an additional electrode 14 is connected to the initiating electrode 9 through a longitudinal section of the dielectric tube. Due to the execution in the indicated form, the system for forming a uniform extended SR is as compact as possible, which minimizes the transverse dimensions of the partially transparent electrode, on the reverse side of which a preionization unit 5 is installed, and reduces the inductance of the discharge circuit.

In embodiments of the invention, each ceramic container 24 is in the form of either a round or rectangular pipe (FIG. 11). In the latter case, a large compactness of the ceramic containers 24 is ensured with a high degree of filling of their volume with ceramic capacitors 12. As a result, a low inductance of the discharge circuit and an increase in the laser efficiency are achieved.

11, surface parts of each ceramic container 10 facing the discharge region 4 are mounted flush with the first electrode 2, forming gas flow guides located upstream and downstream near it. This allows you to generate a high-speed gas flow in the region of discharge 4.

By using a partially transparent electrode, the minimum coefficient K of gas change in the discharge volume at a high pulse repetition rate, which is sufficient to maintain maximum laser efficiency, is reduced. As a result of this, it is possible to increase the repetition rate of discharge pulses, increase the average radiation power at high laser efficiency and reduce operating costs.

An additional factor contributing to a decrease in the inductance of the discharge circuit is that during the preionization through the partially transparent first electrode 2, the insulating surfaces of the ceramic containers 24 facing the discharge region 4 are not exposed to UV radiation by the preionization unit 5, which makes the discharge circuit as compact as possible.

For operation with a high pulse repetition rate, the additional electrode 14 connected to the initiating electrode 9 is preferably provided with a cooled gas stream.

In embodiments of the invention (Figs. 12, 13), aimed at further simplifying the system for forming a CP, the curved dielectric plate 6 is made in the form of a solid dielectric tube, on the front outer surface of which a burning electrode 7 and an additional electrode 14 are diametrically opposed, FIG. .12 is a diagram of this embodiment of the invention with the first electrode 2 made partially transparent. In embodiments of the invention, an additional electrode 14 is connected to the initiating electrode 9 located inside the dielectric tube, through the end face of the dielectric tube, for example by an electrical conductor 37 (Figure 12). In this case, the initiating electrode 9 can be made in the form of a thin metal plate rolled into a tube with a diameter equal to the inner diameter of the dielectric tube (Fig. 12), and the electrical conductor 37 can be part of a thin metal plate (foil).

13 illustrates an embodiment of the invention with a second electrode 3 made partially transparent as part of an excimer laser with a laser tube 1 based on a ceramic tube. An embodiment of the invention using a second electrode made partially transparent provides a minimum inductance of the discharge circuit. This is achieved due to the fact that the preionization unit 5 and the current circuit SR are located outside the discharge circuit of the main volume discharge, which minimizes its inductance.

A discharge system with preionization through a partially transparent electrode (Figure 10-13) is characterized by a small (close to unity) gas change coefficient K in the discharge zone 4, which allows to increase the generation energy and excimer laser power while ensuring its high efficiency.

In accordance with an embodiment of the invention, the initiating electrode 9 may be made of a cooled liquid heat carrier. For this, the initiating electrode may either have a channel 38 for circulation of the coolant (Fig.13).

The discharge system of an excimer laser operates as follows. When you turn on the power source 11 between the first 2 and second 3 electrodes of the laser, as well as on the capacitors 12 connected to them, the voltage begins to increase. The potential of the high-voltage first electrode 2, located on the side of the wall of the gas-filled laser chamber 1, through additional capacitors 13, connecting the power source 11 with the preionization unit 5, located on the side of the second electrode 3 (Figure 1), is transmitted to the extended ignition electrode 7 mounted along the front surface 8 of an extended dielectric plate 6 having a curved shape in cross section. Between the ignition electrode 7 and the initiating electrode 9 of the CP formation system connected to the grounded second laser electrode 3, the voltage also begins to increase. On the front surface 8 of that part of the curved dielectric plate 6, to the reverse surface 10 of which is a cylindrical adjacent extended initiating electrode 9, an ionization wave develops. During the ionization wave propagation from the ignition electrode 7 to the initiating electrode 9, the distributed electric capacitance of the curved dielectric plate 6 is charged to a voltage approximately equal to the voltage of the ignition electrode 7. After the ionization wave propagates from the ignition electrode 7 to the initiating electrode 9, a completed sliding discharge is ignited between them whose current is limited by the charging current of the additional capacitors 13. The electrical capacitance of the additional capacitors 13 is selected a lot times less than the capacitance of the capacitors 12 connected to the first and second electrodes 2, 3, the longitudinal axes of which are parallel to each other. The UV radiation of the superlattice on the surface of the curved dielectric plate 6, forming a cylindrical surface 10 of which are parallel to the longitudinal axes of the first and second electrodes 2, 3, carries out the preionization of the discharge zone 4 between the first and second electrodes 2, 3. The preionization is carried out from the side of the second electrode 3 (Fig. one). After the voltage between the first and second electrodes - 3, 4 reaches the breakdown voltage, the main volume discharge occurs between them. The energy stored in the capacitors 12 is deposited in the volume discharge between the first and second electrodes 2, 3, which with the help of a resonator (not shown) allows to obtain the laser generation energy.

The use of a curved dielectric plate 6 in comparison with a flat one provides a compact system for the formation of superlattices and the laser discharge system as a whole, which reduces the inductance of the discharge circuit, provides the possibility of increasing the pulse repetition rate and increasing the average laser radiation power at high laser efficiency. Moreover, the execution of at least a portion of the dielectric plate adjacent to the initiating electrode, cylindrical provides relative ease of manufacture of the curved dielectric plate 6. Due to the fact that the generators of the cylindrical surface 10 of the curved dielectric plate 6 are parallel to the longitudinal axes of the first and second electrodes 2, 3 , the CP zone is parallel to the zone of volume discharge 4, providing a uniform level of preionization over the entire length of the extended zone of volume discharge 4. This provides a high homogeneity volume discharge laser and its resistance to acoustic disturbances in a mode with high pulse repetition frequency.

In embodiments of the invention (FIG. 1), a CP is implemented on the surface of a curved dielectric plate 6 made in the form of an extended part of a cylindrical thin-walled dielectric tube enclosed between two longitudinal sections of the tube parallel to its longitudinal axis. This simplifies the manufacture of the curved dielectric plate 6. In embodiments of the invention, to further simplify the CP device, the front 8 and the reverse 10 of which are preferably circular cylindrical on the surface of the curved dielectric plate 6.

The connection in embodiments of the invention of the initiating electrode 9 of the CP formation system with the second laser electrode 3 (FIG. 1) ensures the compactness of the device, simplifies it and reduces the inductance of the discharge circuit of the laser, increasing its efficiency.

When working with a high pulse repetition rate, a gas circulation system in the laser chamber 1 is used. The device cycle is repeated when the high-speed gas flow cooled by the tubes of the heat exchanger 21 is provided by a diametrical fan 20 and gas flow guides, which include spoilers 22 and guide vanes 23, will change the gas in the region of discharge 4 between the electrodes 2, 3 after the next laser pulse (Figure 2).

In embodiments of the invention, to increase the generation energy and laser power, preionization is carried out simultaneously by two identical preionization units 5 located on the sides of a solid either the first electrode 2 (Figs. 2, 4, 8) or the second electrode 3 (Figs. 3, 5-7 , 9). To this end, preionization is carried out by preionization units 5, so that each point of the discharge zone 4 is in the line of sight of at least part of the surface of the curved dielectric plate 6 used to form the CP. The execution of the first and second electrode continuous provides their relative simplicity, high reliability and long life.

In the embodiments of the invention (FIG. 2), the current of each CP flows along a circuit including, in addition to pulse-charged additional capacitors 13, additional electrical inputs 18 of the laser chamber 1 made in embodiments of the invention (FIGS. 2, 6, 8) based on ceramic pipes, and gas-permeable additional return current conductors 19, providing the possibility of gas circulation in the laser chamber 1.

In embodiments of the invention, a complete CP current flows between the ignition electrode and at least one extended additional electrode 14 (FIGS. 2-13), preferably connected to the initiating electrode 9, which simplifies the preionization unit 5. In embodiments of the invention, the additional electrode 14 of the formation system CP connected or combined with the second electrode 3 (Figure 2), or with the first electrode (these options are not shown for simplicity). All this simplifies the electrical circuit of the CP formation system.

In embodiments of the invention, the CPs are lit not only on the front surface 8 of the curved dielectric plate 6, but also on its extended lateral edge (Figs. 1, 3-6) and in some embodiments (Fig. 3) along a small part of the back surface 10. This allows further reduce the size of the CP formation system.

The current of the main volume discharge flows along a low-inductance discharge circuit, which includes capacitors 12, current leads of the laser housing 15, 16, gas-permeable return conductors 17, first and second electrodes 2, 3. In addition, a relatively small electric energy stored for pulse charging time in additional capacitors 13, which is partially allocated in the SR.

In the process, the devices ensure the absence of spurious breakdowns between the high-voltage first electrode 2 and the grounded current leads 16 due to their placement at a certain distance from each other. In some embodiments of the invention, the placement of CP formation systems near the second electrode 3 allows minimizing the discharge circuit inductance due to the closest possible approach to the first electrode 2 of the current leads 16 due to the absence of preionization blocks 5 near the first electrode 2 (Figure 2), which increases the efficiency of the high-energy excimer laser .

In the process of operation of the device due to the use of the convex front surface 8 of each curved dielectric plate 6, the preionization blocks 5, which provide a high uniform level of preionization at each point of the discharge zone 4, do not prevent the formation of a high-speed gas flow between the first and second electrodes 2, 3 (Figure 2 ) This improves the uniformity and stability of the volume discharge, provides an increase in the stability of the output characteristics of the laser, as well as the possibility of increasing the aperture of the laser beam, the generation energy, and the average laser radiation power. In addition, the electrodes 7, 9, 14 of the CP formation system are removed from the discharge zone 4 (FIG. 2). This minimizes the distortions introduced by the preionization units 5 into the distribution of the electric field strength in the zone of the volume discharge 4, ensuring the uniformity of the volume discharge and the stability of its uniform shape in the mode with a high pulse repetition rate. As a result, high stability of laser radiation energy from pulse to pulse and high quality of the laser beam are achieved.

To ensure a long life time of the curved dielectric plate 6 as part of the preionization unit 5, as well as a long life time of the laser gas mixture containing extremely chemically active components F ₂ or HCl, erosion-resistant and halogen-resistant dielectrics are preferably used as the material of the curved dielectric plate 6: either sapphire or ceramics, in particular Al ₂ O ₃ .

In the embodiment of the invention (FIG. 2), the initiating electrode 9 and the curved dielectric plate 6 adjacent to it, heated by CP, are cooled during operation, at least in part by heat transfer from the massive metal guide vane 23, which in turn is cooled by a gas stream, circulating in the laser chamber 1.

For effective cooling of the CP formation system in embodiments of the invention, the initiating electrode 9 or the additional electrode 14 may have radiator pins or radiator fins on the rear side perpendicular to the longitudinal axes of the first and second electrodes.

In embodiments of the invention, the initiating electrode 9 is cooled by a liquid coolant, for this the initiating electrode 9 has a channel 38 for circulating the coolant (Fig. 13).

In the example embodiments of FIGS. 4 and 11, using a power source 11, the capacitors 12 and the additional capacitors 13 are pulsed in two ceramic containers 24 located at least partially on the sides of the discharge zone 4 (FIG. 4), or on the sides of the first electrode 2 (Fig.11). The capacitors 12 are charged via a low-inductance electric circuit, which includes sealed high-voltage current leads 25 with ceramic insulators 26 mounted on the side of the first electrode 2 in the metal wall of the laser chamber 1 along it. The low inductance charging circuit of the capacitors 12 also includes current leads 15, 16 installed along the ceramic containers 24 and located inside the laser chamber 1 on both sides of the ceramic containers 24, extended grounded conductors 27 connected to the metal wall of the laser chamber 1. At the same time, auxiliary capacitors 13, also located, are charged. in ceramic containers 24. Charging auxiliary capacitors 13 is carried out through an electrical circuit that includes additional current leads 18 and an extended surface discharge gap between the ignition and additional electrodes 7, 14 of the preionization unit 5. Moreover, the optimized capacitance of the auxiliary capacitors 13 is many times smaller than the capacitance of the capacitors 12, which determines the relatively small energy input into the auxiliary sliding discharge of the preionization unit 5. In each preionization unit 5 UV radiation of an auxiliary complete sliding discharge over the surface of an extended sapphire plate 7 carries out preionization of the gas in the region s to defuse 4. Upon reaching the breakdown voltage across the electrodes 2, 3 therebetween volumetric gas discharge is ignited. The energy stored in the capacitors 12 is invested in a discharge along a low-inductance discharge circuit, including high-voltage and grounded current leads 15, 16 and gas-permeable return conductors 17 located on both sides of the first and second electrodes 2, 3. The discharge provides excitation of the gas mixture in the region of discharge 4, which makes it possible to obtain laser beam generation. When using a gas circulation system containing a diametrical fan 20, water-cooled heat exchanger tubes 21, gas flow guides, which include spoilers 22, guide vanes or vanes 23, and parts of the surface of ceramic containers 24 facing the discharge zone, will change gas in the region discharge 4, the laser cycle is repeated.

In these embodiments of the invention (Figs. 4, 11), the placement of capacitors 12 in ceramic containers 24 allows for a low inductance of the discharge circuit and an increase in the laser efficiency. In addition, the extended parts of the containers 24 facing the discharge zone, forming gas flow guides located upstream and downstream near it, can efficiently generate a high-speed gas flow between the laser electrodes, which makes it possible to realize a highly efficient laser operation with a high average radiation power.

In embodiments of the invention, the CP is ignited on the surface of a curved dielectric plate 6, the front surface of which is concave (Fg.5, 6). Moreover, in embodiments of the invention, the CPs are lit in two identical preionization units 5 located on the sides of either the first electrode 2 (FIG. 5) or the second electrode 3 (FIG. 6). In embodiments of the invention, the flow path of the CP may include current leads 28 provided with ceramic insulators (Figure 6). The curved dielectric plate 6 is preferably made in the form of an extended part of a circular cylindrical thin-walled tube, enclosed between two sections of the tube parallel to its longitudinal axis. In these embodiments of the invention, the surface treatment of the curved dielectric plate 6, more precisely, the outer surface of the workpiece tube, compatible with the surface of the initiating electrode 9, is facilitated. This simplifies the manufacturing technology of the CP formation system with the exact combination of the surfaces of the curved dielectric plate 6 and the extended initiating electrode 9. The result is achieved highly efficient operation of preionization unit 5 by ensuring high uniformity of the superlattice and efficient cooling of the curved die an insulating plate 6 by initiating electrode 9.

In accordance with embodiments of the invention, a portion of the curved dielectric plate not used to form a CP may be located on the back of either the first electrode 2 (FIG. 5) or the second electrode 3 (FIG. 6).

In these embodiments of the invention, along with the simplification of the manufacturing technology of the CP formation system, a small inductance of the discharge circuit is achieved, including by placing part of the curved dielectric plate 6 on the back side of either the first electrode 2 (Figure 5) or the second electrode 3 (Fig .6).

In embodiments of the invention, preionization is carried out from the side of either the first or second electrode (Figs. 7, 8) by two identical systems 5 for forming CP along the surface of a curved dielectric plate 6 made in the form of a cylindrical thin-walled dielectric tube with a longitudinal section 29. In this case, the initiating electrode 14 placed inside the dielectric tube 6, and an additional electrode 14 is connected to the initiating electrode 9 through a longitudinal section 29 of the dielectric tube 6.

When the device is executed in the indicated form, the greatest compactness of the SL formation system and a decrease in the inductance of the discharge system are achieved, which makes it possible to increase the efficiency of a wide-aperture high-energy excimer laser.

The implementation of the curved dielectric plate 6 in the form of a ceramic tube with a longitudinal section 29, along with the compactness of the preionization unit, provides the relative simplicity of the manufacturing technology of the formation system of the CP.

In embodiments of the invention (Figs. 9, 12, 13), the CPs are ignited on the surface of a curved dielectric plate 6, which is used as a solid dielectric tube, inside which an initiating electrode 9 is placed, with an additional electrode 14 placed on the outer surface of the solid dielectric tube. In embodiments of the invention, the additional electrode 14 is preferably connected to the initiating electrode through the end of the dielectric tube, for example, by an electrical conductor 37. In these embodiments of the invention, a slight difference in the operation of the preionization unit is that at the incomplete CP stage, the capacitance of the curved dielectric plate 6 is carried out along the electric circuit including an electrical conductor 37 connecting the additional electrode 14 to the initiating electrode 7 through the end face of the dielectric tube. When performed in this form, the design simplicity of a curved dielectric plate is ensured, its compactness, as well as the low inductance of the discharge system, which increases the efficiency of a high-energy wide-aperture excimer laser.

In embodiments of the invention, the preionization is carried out through a partially transparent either the first electrode 2 (Fig. 10-12) or the second electrode 3 (Fig. 13) by a preionization unit located on the back side of the partially transparent electrode. In these embodiments of the invention, with a CP forming system symmetrical with respect to a plane 30 including longitudinal axes 31, 32 of the first and second electrodes 2, 3, the CPs are lit on both sides of the ignition electrode 7 mounted on the convex cylindrical surface of the curved dielectric plate 6 and connected to a partially transparent first electrode 2 by conductors 34 (Fig.10-13). To ensure the compactness of the electrode assembly and increase the efficiency of the preionization unit 5, the CP is ignited in the immediate vicinity of the discharge zone 4 due to at least partial placement of the preionization unit 5 in an extended niche 35, made on the back side of the partially transparent electrode (Figure 10-13 )

To ensure greater compactness of the electrode assembly in embodiments of the invention, during the operation of the device, parasitic breakdowns between the preionization unit 5 and the partially transparent electrode are prevented due to at least partial placement of an extended ceramic insulator 36 with a π-shape (Figure 10), or -shaped cross-section (not shown) in an extended niche 35 of a partially transparent electrode. In this case, the preionization unit 5 is at least partially placed in an extended ceramic insulator 36 on the back of the transparently transparent electrode 2 (Figure 10). In these embodiments of the invention, the maximum compactness of the electrode assembly and the discharge system of the laser as a whole is achieved.

The implementation of the ignition system of the sliding discharge in the proposed form ensures the compactness of the preionizer located in the immediate vicinity of the partially transparent electrode. Compared with analogues, in which a flat dielectric plate is used to ignite a sliding discharge, the use of a curved dielectric plate in the form of a ceramic tube or its extended part significantly reduces the transverse size of the dielectric plate by up to a factor of seven due to the folding of the plate into the tube. In addition, the implementation of the SR ignition system in the proposed form avoids spurious breakdowns between the partially transparent electrode and the preionizer. All this allows to significantly, up to 2 times, reduce the transverse size of the partially transparent electrode. When using high-energy excimer lasers with a partially transparent electrode, minimizing the size of the highly efficient preionization unit based on a uniform extended SR integrated into the electrode assembly allows one to reduce the transverse dimensions of the partially transparent electrode and increase the generation energy and laser power at its high efficiency. In addition, reducing the transverse dimensions of the partially transparent electrode simplifies the design and technology of its manufacture, increases the reliability and lifetime of the partially transparent electrode, reduces the cost of generating energy during operation of a high-energy excimer laser.

The implementation of the discharge system of an excimer laser in accordance with the invention allows to reduce the transverse dimension of a highly efficient preionization unit with a uniform extended SR in the form of a plasma sheet. Due to this, the compactness of the discharge system and its low inductance are achieved, which increases the efficiency of the high-energy wide-aperture excimer laser and reduces operating costs.

In General, the implementation of the discharge system of the excimer laser in accordance with the invention allows to minimize the inductance of the discharge circuit while providing a high-speed gas flow between the electrodes and a small coefficient K of gas change between the electrodes, which allows to increase the generation energy and power of the excimer laser while reducing the cost of obtaining laser radiation.

INDUSTRIAL APPLICABILITY

The invention allows to create the most high-energy, powerful and highly efficient excimer lasers and laser systems with various combinations of radiation wavelength (from 157 to 351 nm), generation energy (from ~ 0.01 to more than 2 J / pulse) and pulse repetition rate (from ~ 300 Hz up to ~ 6000 Hz) for large industrial enterprises, scientific research and other applications. These include: the production of flat LCD and OLED displays by laser annealing, surface modification and hardening, 3D microprocessing of materials, the production of high-temperature superconductors by pulsed laser ablation, environmental monitoring using powerful UV lidars, the production of integrated circuits using laser VUV lithography, etc.

INFORMATION SOURCES

1. Patent US 6757315.

2. VM M Borisov, D Basting, U Stamm, et al, "Compact 600-W KrF laser", Quantum Electron, 1998, 28 (2), pp. 119-122.

Designations

1. laser camera

2. first electrode

3. second electrode

4. volume discharge zone

5. block preionization

6. dielectric plate

7. ignition electrode

8. the front surface of the dielectric plate

9. initiating electrode

10. the reverse surface of the dielectric plate

11. power supply

12. capacitors

13. additional capacitors

14. additional electrode

15, 16 high-voltage and grounded current leads

17. reverse current leads

18. additional current leads

19. additional return current leads

20. diametrical fan

21. heat exchanger tubes

22. spoilers

23. guide vanes

24. ceramic containers

25. high voltage current leads

26. ceramic insulators

27. long grounded conductors

28. current leads

29. longitudinal section of the dielectric tube

30. a plane including the longitudinal axis of the first and second electrodes

31, 32 longitudinal axis of the first and second electrodes

33. slotted holes of a partially transparent electrode

34. conductors

35. an extended niche on the back of a partially transparent electrode

36. long ceramic insulator

37. electrical conductor

38. channel for the circulation of the coolant

3. V. Borisov, I. Bragin. High-Energy Lasers. In Excimer Laser Technology. Ed. by D. Basting, G. Marowsky. Springer-Verglas Berlin Heidelberg (2005).

4. Patent EP 1 255 646 B1.

5. Patent US20030118072.

6. Patent application RU 2012131330.

7. Patent application RU 2012131348.

8. Coherent Inc. Excimer & UV Optical Systems Product Catalog 2012.

Claims (21)

1. A discharge system of an excimer laser, including an extended first electrode (2) located in the laser chamber (1), mounted on the side of the laser chamber wall (1), a second electrode (3), a volume discharge zone (4) between the first and second electrodes (2), (3), the longitudinal axes of which are parallel to each other, at least one preionization unit (5), containing
a system for generating a uniform complete sliding discharge (CP) between the extended ignition electrode (7) located on the surface of the extended dielectric plate (6) and either the initiating electrode (9) or an additional electrode (14) connected to the initiating electrode (9),
wherein the extended dielectric plate (6) has a curved shape in cross section,
a firing electrode (7) is mounted on the front surface (8) of the curved dielectric plate (6) along it,
an extended initiating electrode (9) is adjacent to the reverse surface (10) of the dielectric plate (6) and at least adjacent to the initiating electrode (9), the extended portion of the reverse surface (10) of the curved dielectric plate (6) is cylindrical. 2. The device according to claim 1, in which the CP formation system is installed so that the generators of the cylindrical surface of the curved dielectric plate (6) are parallel to the longitudinal axes of the first and second electrodes (2), (3). 3. The device according to claim 1, in which the front and back sides (8), (10) of the curved dielectric plate (6) are cylindrical. 4. The device according to claim 1, in which at least a portion of the surface of the curved dielectric plate (6), combined with the surface of the initiating electrode (9), is circularly cylindrical. 5. The device according to claim 1, in which the curved dielectric plate (6) is made in the form of an extended part of a cylindrical thin-walled dielectric tube enclosed between two longitudinal sections of the tube parallel to its longitudinal axis. 6. The device according to claim 1, in which two identical preionization units (5) are located on the sides of either the first electrode (20), made solid, or the second electrode (3), made solid. 7. The device according to claim 1, in which the front surface (8) of the curved dielectric plate (6) is convex. 8. The device according to claim 1, in which either sapphire or ceramic, in particular Al ₂ O _{3, is} used as the material of the curved dielectric plate (6). 9. The device according to claim 1, in which the initiating electrode (9) is made cooled by either a gas stream or a liquid coolant. 10. The device according to claim 1, in which each point of the discharge zone (4) between the first and second electrodes (2), (3) is in the direct line of sight of at least part of the surface of the curved dielectric plate (6) used for formation of SR. 11. The device according to claim 1, in which the front surface (8) of the curved dielectric plate (6) is concave. 12. The device according to claim 1, in which part of the curved dielectric plate (6), not used to form CP, is located on the back side of either the first electrode (2) or the second electrode (3). 13. The device according to claim 1, in which the curved dielectric plate (6) is made in the form of a cylindrical thin-walled dielectric tube with a longitudinal section (29). 14. The device according to claim 1, in which the curved dielectric plate (6) is made in the form of a cylindrical thin-walled dielectric tube with a longitudinal section (29), the initiating electrode (9) is placed inside the dielectric tube, and an additional electrode (14) is connected to the initiating electrode (9) through a longitudinal section (29) of the dielectric tube. 15. The device according to claim 1, wherein either the ignition electrode (7) or the additional electrode (14) is connected either to the first electrode (2) or to the second electrode (3). 16. The device according to any one of paragraphs. 1-5, 7-9, 12, 13, 15, in which either the first electrode (2) or the second electrode (3) is made partially transparent, having on the back side an extended niche (35), in which at least the extended preionization unit (5) is partially placed, while in the preionization unit (5) the CP formation system is made symmetrical with respect to the plane (30) including the longitudinal axes (31), (32) of the first and second electrodes (2), (3 ), and contains two CP zones symmetrically located on both sides of the indicated plane (30). 17. The device according to any one of paragraphs. 1-5, 7-9, 12, 13, 15, in which either the first electrode (2) or the second electrode (3) is made partially transparent, having on the back side an extended niche (35), in which at least partially
an extended ceramic insulator (36) with a U-shaped or U-shaped cross section is placed, and the CP formation system, at least partially located in the extended ceramic insulator (36), contains two CP zones symmetrically located on both sides of the plane ( 30), which includes the longitudinal axis (31), (32) of the first and second electrodes (2), (3). 18. The discharge system of an excimer laser, including an extended first electrode (2) located in the laser chamber (1), mounted on the side of the laser chamber wall (1), a second electrode (3), a volume discharge zone (4) between the first and second electrodes (2), (3), the longitudinal axes of which are parallel to each other, and at least one preionization unit (5), while
each preionization unit (5) contains a system for forming a uniform complete CP on the surface of the whole dielectric tube (6) between the extended ignition electrode (7) and the additional electrode (14) installed on the front surface of the dielectric tube (6) along it, inside the dielectric tube a long initiating electrode (9) is placed adjacent to the back surface (10) of the dielectric tube (6). 19. The device according to claim 18, in which the additional electrode (14) is connected to the initiating electrode (9) through the end face of the dielectric tube. 20. The device according to p. 18 with either a first electrode (2) or a second electrode (3) made partially transparent, having an extended niche on the back side (35), in which at least partially an extended preionization block (5 ), while in the preionization unit (5), the CP formation system is made symmetrical with respect to the plane (30), which includes the longitudinal axes (31), (32) of the first and second electrodes (2), (3), and contains two CP zones symmetrically located on both sides of the indicated plane (30). 21. The device according to any one of paragraphs. 18-20, in which the ignition electrode 7 and the additional electrode 14 are placed diametrically opposite on the front surface of a solid dielectric tube along it.

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