JP2003257698A - Laser plasma x-ray generating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser plasma X-ray generating device capable of decreasing the amount of gas emission from a cryo-material to be emitted upon condensed irradiation with pulse laser beams to a great extent and reducing the capacity of a gas exhausting means to collect the substances generated. <P>SOLUTION: The laser plasma X-ray generating device is structured so that a cryo-target groove 51 is provided at the surface of a rotor 11 and a pressure collecting wall 52 and a gas exhausting nose 53 are fixed to a stationary wall 50 in predetermined positions mating with the cryo-target groove 51. The rotor 11 rotating is cooled by an ultra-low temperature fluid 13, and to the surface of the rotor 11, the cryo-material is spouted from a cryo-target material supplying nozzle 21 which is cooled under control, and thereby a cryo-target layer 22 in the form of crystallized particulates is produced. The pressure collecting wall 52 scratches together the cryo-material in the surrounding area and forms a cryo-target band in the position of the cryo-target groove 51, and a beam condensing irradiation point for the pulse laser beams is located in the center of the band. The cryo-target band is formed in such a dimension that the plasma generated inside does not damage the wall of the base board of the rotor 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryo-target material that changes the state from liquefaction to solidification by cooling a cryogenic material that is chemically inert and is gaseous at room temperature. It is supplied as a cryo target layer by spraying on the surface such as the cylindrical side surface and the bottom flat surface of the rotating body which has a good cylindrical side surface and is cooled to a cryogenic temperature, and this cryo target layer has a high peak power. The present invention relates to a laser plasma X-ray generator that generates pulse X-rays from plasma generated by repeatedly irradiating pulsed laser light.

Particularly, by limiting the amount of fine particles generated by the target material generated and scattered by the irradiation of the repetitive pulsed laser light having a high peak power to a small amount and collecting the fine particles, a stable and high average value can be obtained continuously. The present invention relates to a laser plasma X-ray generator capable of generating output pulsed X-rays.

[0003]

2. Description of the Related Art A high-temperature and high-density laser plasma is generated by focusing a pulsed laser beam having a high peak power on a point having a diameter of 100 μm or less, and irradiating this on a solid target. It is 1 that a pulsed X-ray of brightness is emitted as a laser plasma X-ray.
It has been known since the 970s. Then, as the pulse energy of laser light is improved, investigation of its physical characteristics is progressing.

Regarding the application of laser plasma X-rays, many techniques have been disclosed as medical applications and as light source for X-ray lithography. After that, as part of the laser fusion research, laser plasma X-rays were energetically studied, and the laser wavelength, the intensity dependence, the target element dependence, etc., of the X-ray spectrum intensity were clarified. In particular, it has been found that the total conversion efficiency from the energy of the incident laser to the X-ray energy is extremely high, from several percent to 10 percent, and it is possible to realize a high-energy pulsed YAG laser capable of a high repetition rate of several 100 Hz. With the progress of technology, the development for practical use of laser plasma X-ray having a high average output by high repetition was made.

As a target for generating a plasma by converging an incident laser, US Pat.
syth et al; S. Patent 4,70
No. 0,371 (Oct. 13, 1987) ”. However, all of these targets are copper (C
u), aluminum (Al), gold (Au), etc., which is a solid material mainly composed of a metal, the material near the condensing point evaporated by laser heating is the inner surface of the chamber wall or the laser plasma X-ray that is emitted. There is a problem that the fine particles that collect on the surface of the expensive X-ray mirror and are scattered will damage the surface of the X-ray mirror. The reason is that the solid material of the target material may be deposited and adhered to the surface of the X-ray mirror to strongly absorb the X-rays and / or may become crystal fine particles to damage the surface of the X-ray mirror. This is because the reflectivity of the mirror decreases and the effective intensity of usable X-rays decreases with time. Therefore, it is necessary to regularly replace the expensive X-ray mirror.

Further, since the target used is repeatedly focused and irradiated with laser light, the target has a short life due to evaporation and abrasion, and must be replaced frequently.

Conventionally, in this type of laser plasma X-ray generator, as a method for solving the above-mentioned problems, a substance that is chemically inert and is in a gas state at room temperature, such as xenon (X
A cryomaterial obtained by cooling a rare gas such as e) and liquefying or solidifying it is used for the cryotarget layer.

For example, as shown in FIG. 13, an apparatus for continuously supplying a cryo target made of a cryo material which has been cooled and liquefied or solidified is disclosed in Japanese Patent Laid-Open No. 1-6349 (Japanese Patent No. 2614457). Has been done.

That is, as shown in FIG. 9, a belt conveyor 102 having a continuously moving rotating endless belt is provided inside the vacuum chamber 101, and a liquefied or solidified cryomaterial is supplied from a supply path 103 to the rotating endless belt. Is continuously supplied and deposited on the surface of the substrate to form a cryo target layer 104.

On the other hand, the pulsed laser light enters the vacuum chamber 101 through the entrance, and forms a focused irradiation point 105 on the cryo-target layer 104 attached on the surface of the moving rotating endless belt. Therefore, at the focused irradiation point 105, the cryomaterial of the cryotarget layer 104 is turned into plasma and emits pulse X-rays, and the pulse X-rays are extracted to the outside through the X-ray emission port.

In the cryo target layer 104 which is made into plasma at this converging irradiation point 105 and made a hole, the cryo material is continuously supplied from the cryo material supply path 103 onto the surface of the rotating endless belt, and the cryo target is supplied. Layer 1
04 is restored.

In the laser plasma X-ray generator for transporting the cryo target layer to the laser condensing point by using the above rotating endless belt, the rotating endless belt is cooled only when it comes into contact with the cryogenic rotating body. There is a problem that the life of the rotating endless belt is shortened due to the effects of bending and stretching at an extremely low temperature, and it is difficult to keep the temperature of the surface on which the supplied cryomaterial is supplied at a stable low temperature. There is a problem.

Further, since it is difficult to obtain a uniform thickness along the surface of the cryo target layer formed on the rotating endless belt by being supplied from the supply path of the cryo material, it is difficult to obtain the normal direction of the surface of the cryo target layer. There is also a problem in that the relative position of the converging irradiation point of the laser light with respect to (1) may deviate from a predetermined position depending on the position of the surface, and the intensity of the generated X-ray is not stable.

In order to solve such a problem, instead of a belt conveyor using a rotating endless belt, for example,
As disclosed in Japanese Patent Laid-Open No. 2001-015296, FIG.
There is a device for continuously supplying a cryo target made of a cryo material that can be liquefied or solidified when cooled as shown in FIG.

That is, in the illustrated laser plasma X-ray generator, the rotating body 11 is provided inside the vacuum chamber 110.
1, the rotary body 111 has a rotary shaft 112 rotated by a rotary drive mechanism and a cylindrical surface having good thermal conductivity as the surface of the cryo target, and the cryogenic fluid 113 is internally provided through the rotary shaft 112. It is circulated to cool the side surface to an extremely low temperature.

On the other hand, the target supply mechanism 120 is cooled to be liquefied or solidified and is chemically inert, and gas such as xenon (Xe) at room temperature is used as a cryotarget material from the supply path 121 to the surface of the rotor 111. To form a cryo target layer 122 having a predetermined thickness.

In the laser plasma X-ray generator, the focused irradiation point 130 of the cryo target layer 122 is focused and irradiated with the repetitive pulsed laser light 131 having a high peak power, and the plasma generated here produces pulsed X-rays. 132
Occurs.

As described above, the cryotarget layer 122 reproduced by rotating the rotator 111 can be continuously supplied to the focused irradiation point 130 of the pulsed laser light 131. Therefore, the rotating body 11 having good thermal conductivity
1 is cooled to an extremely low temperature and the cryo target layer 12 is formed on the surface.
When forming 2, the thickness of the cryo target layer 122 can be appropriately set by setting the rotation speed of the rotating body 111, the temperature of the rotating body surface, the supply amount of the cryo material supplied to the rotating body surface, and the like. Further, since the position of the focused irradiation point 130 of the pulse laser can be sequentially moved by the rotation of the rotator 111, it is possible to prevent damage to the rotator 111 due to the plasma generated at the focused point of the pulse laser.

Further, as shown in the figure, a fixed wall 150 is provided which surrounds the rotating body 111 with a gap and receives the cryomaterial for confining in the gap to set environmental conditions including the speed and the ambient temperature of the rotating body 111. , Rotating rotating body 111
The cryo-material adhering to the cylindrical surface of is formed into a cryo-target layer 122 with a substantially uniform thickness. Therefore, the cryo-target layer in the liquefied state or the solidified state can be stably formed on the surface of the rotating body 111, and plasma is always generated at the focused irradiation point 130 of the pulsed laser light 131 under the same stable condition. be able to.

However, as shown in FIG. 15, with the cryo target layer 122 formed on the surface of the rotating body 111 described above, the pulse laser light 1 of 0.7 J / 20 ns is used.
When 31 is irradiated to the focused irradiation point 130, high-temperature and high-pressure plasma is formed on the surface of the cryo target layer 122 within 30 ns, and pulse X-rays 132 are generated. At the same time, a shock wave driven by the generated plasma propagates inside the cryo target layer 122, and after passing through the shock wave,
During a period from 1 μs to almost 100 μs, the gas 134 from which the cryo-material serving as the cryo-target is evaporated and the crushed fine particles 135 are diffused to form the crater 136 on the cryo-target layer 122 having a predetermined thickness. When xenon (Xe) is used as the cryo target material, the crater 136 reaches a depth of 150 μm and a diameter of 400 μm. Incidentally, the volume of the cryo target material required to emit the pulsed X-rays due to the formation of plasma is 100 μm.
It is the product of the area by the diameter of the focused spot and the depth of 20 μm.

[0021]

In the laser plasma X-ray generator described with reference to FIG. 10 described above, the cryo-target material (Xe) has a depth of 150 μm and a diameter of 400 μm for focused irradiation with a diameter of 100 μm. It is spreading the amount that it reaches. Therefore, these generated substances diffuse into the vacuum chamber without damaging the components in the vicinity of the converging irradiation point where the diffusing gas and fine particles rotate.
Further, this generated substance is rapidly increased by staying in the vacuum chamber, and there is a high risk of degrading the function of the device. In order to eliminate this, an exhaust means such as the exhaust device 140 shown in FIG. 12 can be provided to recover and regenerate the generated substance, but since the diffusion amount increases rapidly, a large exhaust amount is required. Needed.

An object of the present invention is to solve such a problem in a laser plasma X-ray generator using a rotating body as a substrate for a cryo target layer. Limit the amount of the cryo-target material that evaporates or diffuses to the smallest possible amount to reduce the capacity of the exhaust means that collects the generated substances, and collect the generated substances as much as possible to reduce the cost of equipment and its operation. An object of the present invention is to provide a laser plasma X-ray generator that can be reduced.

[0023]

A laser plasma X-ray generator according to the present invention rotates a cryo-target material which is chemically inert, gaseous at room temperature, and turns from liquefied to solidified when cooled. It has a shaft and has a cylindrical surface that rotates around this axis of rotation and has a good thermal conductivity, and is supplied to the side or bottom surface of a rotating body that is cooled to cryogenic temperature and formed to a predetermined thickness. The formed cryo target layer is formed as a cryo target, and pulse X-rays are generated from plasma generated by converging and irradiating the cryo target with repetitive pulse laser light having high peak power.

One of its characteristics is the width and thickness of the size capable of ensuring the minimum amount of the cryo-target material required to generate plasma and emit X-rays when the pulsed laser light is focused and irradiated. That is, a cryo-target having one or more rounds is provided on the surface of the rotating body in the form of a ring-shaped circle. Such a cryo target band may be formed with a thickness on the surface of the rotating body or may be formed with a groove having a depth on the surface of the rotating body. Of course, the cryo target band can also be formed on the shallow groove.

In this case, the cryo-target material supply port jets a cryo-target material, which has been cooled in advance and has a concentration close to that of a liquid state, onto the surface of the rotator and immediately solidifies the surface of the rotator to solidify the cryo-target zone in the state of crystalline particles. It is preferably a cryo target supply nozzle to be formed.

Further, the cryo-target band may be formed on the surface of the rotating body in parallel with the side surface in the direction of the rotation axis and on the bottom surface with concentric circles. In addition, a feature added to this is that the cryo target material that is fixedly arranged on the cryo target band of the rotating body that rotates and adheres closely to the surface of the rotor and that adheres to the surface of the rotor around the cryo target band. It is to be provided with a pressure collecting wall for scraping and pushing it into the cryo target band to create a cryo target band having a predetermined size.

Further, the amount of the cryo-target material that is vaporized while being converted into plasma while being focused and irradiated by the pulsed laser light is, for example, xenon (Xe) having a thickness of 20 μm.
It is about 30 μm. As described above, by setting the width and thickness or depth of the cryo target band to a value commensurate with the amount of transpiration due to the converging irradiation of the laser light, that is, the converging spot diameter and the transpiration depth, the cryo target Evaporation of the material is limited in the width direction of the target groove and does not spread to the surface of the rotating body substrate. In particular, when the size in the width direction is limited by using the pressure collecting wall, extra evaporation in the width direction does not occur.

Further, the opening portion of the cryo target groove is wider than the central portion so that the high temperature plasma particles scattered at the portion where the cryo target groove is in contact with the surface of the rotating body substrate do not damage the rotating target substrate. It is desirable that the cross section is concave.

Further, in order to avoid damaging the rotor substrate by the plasma, a buffer layer gas, for example, carbon dioxide gas (CO ₂ ) is liquefied and solidified to form a buffer layer on the rotor surface. The cryo target material such as (Xe) can be minimized. In this case, the buffer material supply nozzle that supplies the gas that serves as the buffer layer is arranged at a position upstream of the cryotarget material supply nozzle.

Another feature is that the crystal fine particles of the cryomaterial and its vaporized gas ejected from the focused irradiation point by the focused irradiation of the pulsed laser light are rotated in the rotating body rotating direction from the focused irradiation point, In addition, an exhaust nose for collecting and exhausting air on the cryo target zone is further provided. This feature is preferably combined with the features described above, but can also be independently effective. In particular, fine particles scattered from the focused irradiation point in a direction almost perpendicular to the surface of the rotating body are naturally collected by the exhaust nose obliquely arranged in the rotating direction of the rotating body, that is, the tangential direction of the circular cryo-target zone. Will be possible. Therefore, it becomes easy to collect the cryo target material, and the residue of the cryo target material gasified in the vacuum chamber can be significantly reduced.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. The shapes or features of the figures or the relative dimensions are created for the purpose of understanding the explanation, so please refer to them only for reference.

FIG. 1 is a schematic vertical sectional view for explaining an embodiment of the present invention.

In the laser plasma X-ray generator shown in FIG.
Vacuum chamber 10, cylindrical rotor 11, rotor 11
The rotating shaft 12 and the cryogenic fluid 13 that cools the rotating body 11 inside forms the main structure. The target material supply unit 20 that supplies the cryo material that is the target of the laser light has the cryo target material supply nozzle 21 that supplies the cryo material on the surface of the rotating body 11, and the cryo material is the cryo target layer on the surface of the rotating body 11. 22 is formed.

The pulsed laser light 31 is focused on the focused irradiation point 30 on the cryo target layer 22 on the surface of the rotating body 11 to generate plasma, and the pulsed X-ray 32 is emitted. An X-ray mirror 33 is provided to collimate the radiation of the pulsed X-rays 32 in the output direction. The gas of the cryo material generated in the vacuum chamber 10 by the impact of plasma generation is collected by the exhaust device 40 and collected in the collection layer 41. The fixed wall 50 is provided with a gap from the surface of the rotating body 11,
The cryogenic material is injected and confined in this gap, and as described in the above-mentioned Japanese Patent Laid-Open Publication,
A cryo target layer 22 having a stable thickness in a liquefied state or a solidified state is formed on the surface of 1.

Further, the feature of the present invention that is largely different from the conventional one is that the cryo target material supply nozzle 21 for supplying the cryo material injects the cryo material onto the surface of the rotating body 11, and the cryo material is used as the surface. That is, it is solidified immediately and adhered in the form of crystalline fine particles. Furthermore, the target groove 51, the pressure collecting wall 52, and the exhaust nose 53 are provided. Here, it is assumed that the cryotarget material supply nozzle 21, the pressure collecting wall 52, and the exhaust nose 53 are fixed to the fixed wall 50. The target groove 51 is to embed a cryo material inside to form the above-mentioned cryo target band. The fixed wall 50 is necessary to keep the high vacuum degree of the vacuum chamber 10 in order to isolate the injection portion having a relatively high pressure and the surroundings of the cryo target band from the vacuum.

Further, in the figure, a rotary bearing, a rotary drive mechanism and an axial drive mechanism for driving the rotation and movement of the rotary body 11, and an introduction pipe and an exhaust pipe for the cryogenic fluid 13,
Are shown. Therefore, for example, the axial drive mechanism can form the plurality of cryo target bands described above by stepwise moving the rotating body 11 in the axial direction.

Next, the function of each component will be described with reference to FIG.

Inside the vacuum chamber 10, a rotating body 11 having a cylindrical surface and being hollow and serving as a cooling tank and having high thermal conductivity is provided.
Are provided with a rotation axis 12 perpendicular to the horizontal plane.
The rotary shaft 12 is supported by a rotary bearing provided in the vacuum chamber 10. The rotating shaft 12 is preferably made of a material having a small thermal conductivity coefficient.

Further, the rotary shaft 12 is, at its upper part, an introduction pipe for introducing a low temperature liquefied gas such as liquid nitrogen, liquid argon or liquid helium as a cryogenic fluid 13 into the hollow inside of the rotating body 11 from the outside. An exhaust pipe for discharging and recovering vaporized gas of the cryogenic fluid 13 is coaxially provided. Therefore, the cryogenic fluid 13 is accumulated as a liquid inside the hollow inside the rotating body 11, and the heat conduction of the rotating body 11 is used to bring the surface of the rotating body 11 to a temperature below the liquefaction temperature of the cryomaterial that becomes the cryotarget layer 22. Cooling.

On the other hand, the cryomaterial is, for example, xenon, which is a target material which is a target for converging and irradiating the laser light 31 for generating laser plasma. The cryomaterial is fluidized and supplied to the recovery tank 41 from the outside and stored inside. Further, the cryo-material is jet-supplied by a temperature-controlled cryo-target material supply nozzle 21 to the periphery of the target groove 51 portion provided on the surface of the cooled rotating body 11 at a concentration close to that of a liquid state, and crystal particles In this state, the inside of the target groove 51 is filled and the cryo target layer 22 is formed on the surface of the rotating body 11.

Here, the target groove 51 shown in FIG. 1 and the cryo target layer 22 formed on the surface thereof will be described with reference to FIGS. 2 and 3 together with FIG.

The rotating body 11 is, for example, copper (Cu) whose surface is covered and protected by a refractory metal tungsten alloy or the like.
Is a cylindrical target substrate, and has a thickness sufficient to fill the depth of the target groove 51.

As shown in FIG. 2, the target groove 51 shown in FIG. 1 has a ring shape centered on the rotation axis on a plane perpendicular to the rotation axis 12. It is preferable that the formation of the cryo target layer and the generation of the pulse X-rays alternately occur during one round of the rotating body 11 so that the pulse X-rays 32 can be continuously generated. However, if necessary, the target groove 51 can form a plurality of parallel lines in the direction of the rotating shaft 12 on the cylindrical side surface of the cylindrical rotating body 11 in combination with the above-described axial driving mechanism. Further, another target groove can be provided on the circular bottom surface of the cylindrical or disk-shaped rotating body. In this case, the plurality of target grooves form a plurality of concentric circles centering on the rotation axis.

The target groove 51 has a cross-sectional size of, for example, a depth of 100 μm and a width of 150 μm in the deep portion, and a depth of 15 μm and a width of 300 μm in the shallow portion. The size of the target groove 51 is a transpiration phenomenon in which the pulsed laser light 31 is directly heated, and has a volume that does not damage the rotating body 11 that is the substrate material.

Therefore, the cryomaterial sprayed from the cryotarget material supply nozzle 21 fills the target groove 51 of the rotor 11 which has been cooled to an extremely low temperature and has good thermal conductivity, and has a thickness of 10 μm on the cylindrical surface, for example. The cryo target layer 22 is formed. In this case, the thickness of the cryo target layer 22 can be appropriately formed by setting environmental conditions such as the rotation speed of the rotating body 11, the temperature of the cylindrical surface, and the supply amount of the cryo material supplied to the cylindrical surface.

The target groove 51 has two steps of a shallow portion and a deep portion so that the substrate material is not damaged at the portion where the target groove 51 and the substrate surface of the rotating body 11 are in contact with each other. Other shapes, for example funnel-shaped or semi-circular in cross-section, may be used.

That is, when the target groove has a concave structure instead of the stepped shape as shown in the drawing, the reflected shock wave reflected on the inner surface of the target groove is converged to the central portion of the target groove. It is desirable because it does not diffuse around the target groove to detach or peel off the surrounding target material in a wide range.

Here, returning to FIG. 1, the description will be continued.

As will be described later, since the pressure collecting wall 52 embeds the cryo target material inside the target groove 51,
It is desired that the cryomaterial be in the state of crystalline fine particles on the surface of the rotating body 11. Therefore, the cryo-material is supplied by the cryo-target-material supply nozzle 21 whose temperature is controlled to a low temperature to spray the cryo-material onto the surface of the cooled rotator 11 for rapid cooling to ensure the generation of crystal fine particles. Further, the tip of the cryo target material supply nozzle 21 has a pressure collecting wall 52.
Since it is located inside, the sprayed cryomaterial can be prevented from scattering over a wide range on the surface of the rotating body 11.
As a result, the efficiency of forming the cryo target band is improved.

Further, the cryogenic material which has turned into a gas when the cryo target layer 22 is turned into plasma is discharged and recovered outside the vacuum chamber 10 by the exhaust device 40, sent to the cryomaterial recovery tank 41, and cooled. Then, the temperature is lowered again, and subsequently the liquid is supplied to the surface of the rotating body 11 in the vacuum chamber 10 through the cryo target material supply nozzle 21. Further, an exhaust device 40, the inside of the vacuum chamber 10 133 × ^{10 -} running to hold the 3 Pa or less pressure.

On the other hand, the pulsed laser light 31 is irradiated from the laser entrance of the vacuum chamber 10 through the converging mechanism and reaches the converging irradiation point 30 of the cryo target layer 22.
Next, the pulsed X-ray 32 generated from the plasma generated at the focused irradiation point 30 is formed into parallel light by the X-ray mirror 33 and X-rays are formed.
It is emitted from the line emission port.

Next, as shown in FIG. 4 and FIG.
The pressure collecting wall 52 is located above the target groove 51, and
Is located in front of the focused irradiation point 30 in the rotation traveling direction of.
The exhaust nose 53 is located above the target groove 51, ahead of the focused irradiation point 30 in the rotational traveling direction of the rotating body 11 and in the tangential direction of the circular target groove 51. The exhaust nose 53 is connected to the exhaust device 40 as shown in the figure, and the collected exhaust material is recovered in the recovery tank 41.

In the example shown in FIG. 4, the pressure collecting wall 52 and the exhaust nose 53 are fixed to the fixed wall 51 surrounding the cylindrical rotating body 11 with a gap inside the vacuum chamber 10. However, it goes without saying that the pressure collecting wall 52 and the exhaust nose 53 may be directly fixed to the vacuum chamber 10 itself. Further, FIG. 4 is a view showing a cross section perpendicular to the rotary shaft 12, which is removed from the target groove 51 portion.

Next, the main operation procedure according to the present invention will be described with reference to FIG. 1 together with FIGS. 4 to 8.

First, after the cylindrical surface of the rotating body 11 is cooled to a temperature sufficient to crystallize the cryomaterial into fine crystal grains, the cryomaterial is subjected to the target groove 51 of the rotating body 11.
It is jetted from the cryo target material supply nozzle 21 to the surface including. As a result, the cryomaterial is immediately solidified on the surface of the rotating body 11 to be crystal fine particles. The cryo target layer 22 made of this cryo-atomized crystal material
Are formed in the rotational traveling direction of the rotating body 11, as shown in FIG. The cryo target layer 22 is the rotating body 11.
Is formed on the surface of the substrate with a thickness of, for example, 10 μm to 50 μm.

Next, as shown in FIGS. 5 and 6, the pressure collecting wall 52 slides on the surface of the rotating body 11 to scrape up the crystal fine particle-shaped cryomaterial of the cryo target layer 22 deposited on the surface, It is packed in the target groove 51 and compressed to form the cryo target band 23.

The light source of the pulsed laser light 31 incident on the cryo target band 23 is a pulsed laser light source of high peak power and high repetition type.
Is focused and irradiated onto the surface of the cryo target band 23 as a focused irradiation point 30 with a spot diameter of about 100 μm. In this case, the laser intensity on the surface of the cryo target band 23 is about 10 ¹² W / cm ² .

By the focused irradiation of the pulsed laser light 31, a plasma 24 is generated in the cryo target band 23 around the focused irradiation point 30. After the generated plasma is extinguished, the cryomaterial generates vaporized gas 34 and also generates fine particles (debris) 35. After this, crater-like traces 36 are generated on the cryo-target zone 23. This trace 3
6 exposes the target groove 51 around the focused irradiation point 30. However, the thickness of the cryomaterial that the pulsed laser light 31 having a focused spot diameter of about 100 μm directly scatters as plasma is the ablation rate formula that is experimentally measured in the case of the cryotarget material of xenon (Xe). The depth is up to about 30 μm. In fact, it is due to conduction heating by the plasma and shock waves that craters having a greater depth than this occur.
Therefore, if the thickness of the cryo target layer left after vaporization of the cryo target material as plasma is sufficiently thick against the shock wave, the surface of the copper of the rotating body 11, which is the substrate material, for example, covered with the tungsten alloy is damaged. I will not receive it.

On the other hand, a pulsed laser is used at a repetition frequency of 30.
Stable pulsed X-ray 3 operated at 0Hz-6000Hz
In order to obtain 2, it is necessary to irradiate the surface of the new cryo target band 23 every pulse. Therefore, the number of revolutions per minute is obtained as the rotational speed of the rotor 11 from the distance from the focused irradiation point 30 to the next focused irradiation point on the surface of the cryo target band 23, and the radius and angular velocity of the rotor 11. To be

That is, the trace 36 is replenished with the cryomaterial from the cryotarget material supply nozzle 21 for reuse. Therefore, depending on the relationship between the time required for replenishment and the number of the cryo target material supply nozzles 21 on the cryo target groove 51 for one round, not only the rotating body 11 is rotated by the rotating shaft but also the rotation shaft is rotated when necessary. By reciprocating in the direction, the same location on the surface of the cryo target band 23 is prevented from overlapping with the pulse laser light 31 within a short time. That is, a plurality of target grooves 51 are formed on the side surface of the rotating body 11 shown in the figure. The apparatus is configured to spray the cryo material from the cryo target material supply nozzle 21 onto the crater-like traces 36 during the rotation of the rotating body 11 to immediately repair the traces 36.

Further, as shown in FIG.
The surface velocity υ (= ω × r) of the cryo-target zone 23 can be obtained from the product of the angular velocity ω of r and the radius r to the surface. On the other hand, the irradiation of the pulsed laser light 31 causes the rotating body 11
The fine particles (debris) diverging at a velocity υ _D in the direction perpendicular to the surface of the surface have a combined velocity of (υ _D ² + υ ² ) ^1/2 due to the surface velocity ν of the cryo-target zone 23. Moves leaning in the direction.

On the other hand, the exhaust nose 53 has an opening at this position. That is, the amount Q of gas that can be exhausted is equal to the product of the exhaust speed S and the degree of vacuum (pressure) P, but as described above,
The pressure in the vacuum chamber 10 must be on the order of 10 ⁻³ Torr or less. On the other hand, the pressure in the exhaust nose 53 is about 10 ⁻² Torr, and the exhaust device 4 shown in FIG.
Since 0 is inhaled, the particulates and the gas sucked into the exhaust nose 53 are efficiently exhausted.

Next, another embodiment different from the above will be described with reference to FIG. 9 and FIG.

The difference between this embodiment and the one described above is the rotating body 61 having no target groove and the pressure collecting wall 62 having a notch at the tip. The pressure collecting wall 62 slides on the surface of the rotating body 61 to scrape the crystalline fine particle cryomaterial of the cryotarget layer 22 deposited on the surface and compresses it to form the cryotarget band 63. Therefore, the pressure collecting wall 6
The inner wall of 2 has a shape that narrows toward the notch at the tip, and the shape of the notch determines the cross-sectional shape of the cryotarget band 63.

The formed cryo target band 63 is
As described above, it has at least the width of the focused spot diameter of the laser light and the thickness commensurate with the amount of the cryo target material evaporated and diffused by the plasma generation.
Further, the cryo target zone 63 is formed by the pressure collecting wall 62 so that the cross section thereof is a small mountain having a skirt capable of minimizing gasification of the cryo material.

Here, the shape in which the target groove is not formed on the rotating substrate has been described, but it is preferable to form the cryo target layer by forming the shallow target groove in order to form a stable cryo target band.

As described with reference to FIG. 8 above, if the thickness of the cryo target layer left after the cryo target material is vaporized as plasma is sufficiently thick with respect to the shock wave, the substrate material is The surface of a rotor 11 is not damaged, but if necessary, the rotor 11
It is conceivable to further insert a cushioning material on the surface of the.

Next, referring to FIGS. 11 and 12 in combination, another embodiment different from the above using a cushioning material will be described.

The basic difference between this embodiment and the one described above is that the surface of the rotating body 71 and the cryo-target band 7 are different.
In order to prevent the substrate of the rotating body 71 from being damaged by plasma, a gas, for example, carbon dioxide gas (CO ₂ ) is liquefied and solidified to form the buffer layer 73 of dry ice. As a result, the cryo target band 7
Since the amount of the xenon (Xe) or other cryo-target material that becomes 4 can be minimized, the amount of the cryo-target material that evaporates and gasifies and becomes fine particles can be suppressed. Therefore, the generated pulse X-ray 32 is not attenuated in the vacuum chamber.

That is, as shown, the buffer layer 73
The buffer material supply nozzle 70 for supplying the gas to be used is arranged on the cryo target band 74 at a position upstream of the cryo target material supply nozzle 21.

A target groove 72 having a concave cross section is formed on the surface of the rotating body 71 so that the buffer layer 73 can form a thickness between the cryo target band 74 and the substrate surface of the rotating body 71. Has been done.

Further, the pressure collecting wall 75 slides on the surface of the rotating body 71 to scrape and collect the crystalline fine particle cryomaterial of the cryo target layer 74 deposited on the surface, and compresses it to form the cryo target band 76. The inner wall of the pressure collection wall 76 has a shape that narrows toward the notch at the tip, and the shape of the notch determines the cross-sectional shape of the cryotarget band 76. As described above, the cryo target band 76 has a mountain structure having a skirt in its cross section.

Since the gas material to be the buffer layer 73 has a liquefied and solidified temperature largely different from that of a cryomaterial such as xenon, it is easy to separate them.

In the above description, a plurality of cryo target bands are provided on the side surface of the rotary member in parallel with the direction of the rotation axis and on the bottom surface in a concentric pattern about the rotation axis. However, the cryo target band should be spiral. You can also In this case, the positions of the pressure collecting wall and the tip of the exhaust nose are fixed or moved and adjusted in the axial direction of the rotating body or in the direction perpendicular to the axis.

As described above, although the above description has been made with reference to each of the drawings and showing appropriate conditions, the configurations and combinations such as the shapes and sizes and the mutual positions illustrated and described together with the environmental conditions. The present invention is not limited to the above description, as long as the functions described above are related to each other but satisfy the above functions.

[0076]

As described above, according to the present invention, the cryo-target material in the form of fine crystalline particles is scraped by the pressure collecting wall and pushed into the surface of the rotating body which is cooled by a cryogenic fluid or the like and has a high heat conduction efficiency. A cryo target band is formed, and a focused irradiation point of pulsed laser light is placed at the center thereof. Since the cryotarget zone has a size that plasma generated inside does not damage the wall of the rotating body substrate, only the cryotarget material forming the cryotarget zone is evaporated and scattered. Therefore,
It is possible to avoid excessive evaporation and scattering of the cryo target material due to conduction heating by plasma and shock waves.

As a result, the amount of cryogen gas released inside the vacuum chamber is greatly reduced, so that the absorption of generated X-rays is reduced. As a result, the power of the exhaust system can be greatly reduced, which is economically effective. large. Particularly, the collection of fine particles immediately after the generation of plasma X-rays further improves such an effect.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an outline of a vertical section in the present invention.

FIG. 2 is a diagram showing an embodiment of a groove portion on the side surface of the rotating body of FIG.

FIG. 3 is a diagram showing an embodiment of a partial cross section in FIG.

FIG. 4 is a view showing an embodiment of a cross section of a main part of a rotary body in FIG.

5 is a diagram showing an embodiment of a development plane and a cross section thereof around the converging irradiation point in FIG.

6 is a diagram showing an embodiment of a cross section and a front cross section according to the pressure collecting wall of FIG.

FIG. 7 is a diagram showing an embodiment of the exhaust nose of FIG.

FIG. 8 is a diagram showing an embodiment of an explanation concerning a process of X-ray generation of the present invention.

FIG. 9 is a diagram showing an embodiment of a development plane and a cross section thereof around a converging irradiation point different from FIG.

FIG. 10 is a diagram showing an embodiment of a lateral cross section and a front cross section according to the pressure collecting wall of FIG. 9;

FIG. 11 is a diagram showing an embodiment of a cross section of a main portion of a rotating body, which is different from that of FIG. 4;

FIG. 12 is a diagram showing an embodiment of a cross section of the cryotarget band portion of FIG. 11.

FIG. 13 is a perspective view showing a conventional example.

FIG. 14 is a diagram showing an example of an outline of a conventional vertical section.

FIG. 15 is a diagram showing an example of a description of a conventional process of X-ray generation.

[Explanation of symbols]

10 vacuum chamber 11, 61, 71 rotating body 12 rotation axes 13 Cryogenic fluid 20 Target material supply section 21 Cryo target material supply nozzle 22,74 Cryo target layer 23, 63, 76 Cryo target belt 30 Focused irradiation point 31 pulsed laser light 32 pulse X-ray 33 X-ray mirror 34 Vaporized gas 35 Fine particles (debris) 36 Traces 40 exhaust system 41 collection tank 50 fixed wall 51, 72 Cryo target groove 52, 62, 75 Pressure collecting wall 53 Exhaust nose 70 Buffer material supply nozzle 73 Buffer layer

Claims (7)

[Claims] 1. A cryo-target material which is chemically inert, is gaseous at room temperature, and solidifies from being liquefied when cooled, is gaseous, has a rotation axis, and rotates about the rotation axis as a central axis. Also, the cryo target is a cryo target having a cylindrical shape with good thermal conductivity, which is supplied to and attached to the surface of a rotating body that is cooled to an extremely low temperature and formed to have a predetermined thickness on the surface. Laser plasma X for generating pulsed X-rays from plasma produced by concentrating and irradiating repetitive pulsed laser light with high peak power
In the line generator, the cryotarget layer corresponds to at least the width of the spot size when the pulsed laser light is focused and irradiated, and at least the cryotarget material that evaporates and scatters when the pulsed laser light is focused and irradiated. A laser plasma X-ray generation device having a thickness that secures a sufficient amount, and is a ring-shaped cryotarget band that forms at least one round on the surface of the rotating body. 2. The cryotarget material supply port according to claim 1, wherein the cryotarget material is cooled in advance and jets the cryotarget material having a concentration close to a liquid state onto the surface of the rotating body,
A laser plasma X-ray generator, comprising a cryotarget material supply nozzle for forming the cryotarget zone in the form of crystalline particles. 3. The surface of the rotator according to claim 1, wherein an amount corresponding to the cryotarget material that evaporates and scatters when the pulsed laser light is focused and irradiated is provided on the surface of the rotating body. A laser plasma X-ray generator having a target groove having a width and a depth that can be ensured. 4. The laser plasma X-ray generator according to claim 3, wherein the target groove is formed wider at the opening portion than at the central portion and has a concave shape. 5. The rotating member according to claim 1, which is a buffer layer between the cryo-target zone and the surface of the rotating member, and is a gaseous material at room temperature and solidified from liquefaction when cooled. A laser plasma X-ray generator further comprising a buffer material supply nozzle for supplying and adhering to the surface of the. 6. The rotary target according to claim 1, wherein the rotary body is fixedly arranged on a cryotarget band of the rotating body, and closely contacts and slides on the surface of the rotary body to adhere to the surface of the rotary body around the cryotarget band. The laser plasma X-ray generation device further comprising a pressure collecting wall for scraping and collecting the cryo target material and pushing it into a predetermined shape to form the cryo target band. 7. The cryo target according to claim 1, wherein the cryo target material ejected from the focused irradiation point by the focused irradiation of the pulsed laser beam is based on the rotation direction of the rotating body from the focused irradiation point. The laser plasma X-ray generation device further comprising an exhaust nose that collects and exhausts at a tangential upper part of the target zone.