JPH02239600A - Light storage ring - Google Patents

Abstract

PURPOSE:To make it possible to generate the interference of SOR and to pick up the SOR of a single color responding to a specific wavelength and the wavelength of its higher harmonics as an output light by setting adequately the curvature radius of a reflection device of the SOR arranged to surround the outer periphery of the orbit of charged particles at the reflection point. CONSTITUTION:In order to give an adequate light passage difference to make the mutual interference between an SOR output from a certain bunch and reflected and an SOR output from a bunch advancing thereafter or its reflected light, the curvature radius of a reflection mirror 2 and the curvature radius of the orbit 1 of charged particles are set in a specific value described later. By setting the curvature radius of the reflection mirror 2 and the orbit 1 of the charged particles in such a specific value, the SOR output from the first bunch 6 at the point A on the orbit 1 of the charged particles at a specific time can be crossed to the second bunch 7 running on the orbit 1 of the charged particles by reflecting the SOR at the point B on the reflection mirror 2. In this case, the SOR output from the first bunch 6 and that output from the second bunch 7 can be interfered each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a prestorage ring using a synchrotron radiation generator.

[Conventional technology]

Recently, synchrotron radiation devices that generate synchrotron radiation in the tangential direction of a trajectory by moving charged particles at a speed close to the speed of light along a trajectory with a predetermined curvature have been attracting attention. The present inventor installed a reflecting mirror in such a synchrotron radiation device so as to surround the outer periphery of the R electron particle trajectory, and by reflecting the synchrotron radiation with this reflecting mirror, the synchrotron radiation was reflected by the reflecting mirror. Patent application Sho H-22854 for a light storage ring that accumulates inside
This was clarified in the Specification No. 3. With such a light storage ring, the utilization efficiency of synchrotron radiation light can be significantly improved compared to a normal synchrotron radiation device. Therefore, this kind of light storage ring is simply an ultra-LS
It can be expected to have a wide range of applications, not only in microfabrication such as I, but also in laser processing equipment, laser fusion equipment, etc.

[Problems to be Solved by the Invention] Furthermore, if monochromatic synchrotron radiation light can be extracted as emitted light in this light storage ring, the fields of use and application of the light storage ring will be further expanded. Conceivable.

However, the light storage ring according to the above proposal is limited to improving the utilization efficiency of synchrotron radiation light, and does not take into consideration the extraction of monochromatic light.

Therefore, an object of the present invention is to provide a light storage ring capable of extracting monochromatic synchrotron radiation light.

[Means for Solving the Problems] According to the present invention, synchrotron radiation is generated in the tangential direction of the trajectory by moving a charged particle at a speed close to the speed of light along a trajectory having a predetermined curvature, By reflecting the synchrotron radiation light by a reflecting means arranged so as to surround the outer periphery of the orbit, the synchrotron radiation light is accumulated in the reflecting means, and the accumulated synchrotron radiation light is converted into an output beam. In a light storage ring that extracts light through a light JI' output means, at least one of interference between the synchrotron radiation light and reflected light of the synchrotron radiation light and interference between the reflected lights is used. As a result, a light storage ring is obtained which is characterized by being able to emphasize a monochromatic component having a specific wavelength and its harmonics.

[Embodiment f111 With reference to FIG. 1, a synchrotron radiation light generating device, ie, a light storage ring, according to an embodiment of the present invention will be explained.
, The optical storage ring shown in FIG. 1 is equipped with a circular vacuum container (not shown) and a magnetic field generator (not shown) constituted by a deflection magnet such as a superconducting electromagnet. Charged particles are introduced into a vacuum vessel from an incident accelerator via an inflector or the like. Inside the vacuum container, a magnetic field reaching several Teslas is generated by the above-mentioned magnetic field generator, so the incident charged particles trace a circular trajectory with a curvature determined by the strength of the applied magnetic field and travel at a speed close to the speed of light. exercise with. Here, the center of curvature of the charged particle trajectory 1 is assumed to be O. The charged particles move in a state where they are locally densely packed on a circular orbit l, forming a plurality of bunches.

The length and number of bunches are determined by the operating conditions and design conditions of the synchrotron radiation generator. Each bunch orbits on the charged particle trajectory 1 at a speed close to the speed of light while maintaining equal intervals. In this example, a circular charged particle trajectory 1
The description will be made assuming that the radius of is r and that the first and second bunches 6 and 7 are orbiting on the charged particle trajectory 1. In this state, each bunch 6 and 7 emits synchrotron radiation in the tangential direction of the circular charged particle trajectory 1.

The illustrated light storage ring has a reflection tf 12 that entirely surrounds the outer periphery of a circular charged particle trajectory 1 and a pre-extraction port 3 provided in a part of the anti-#1 mirror 2. Here, the charged particles will be explained as electrons, but they may also be positrons, ions, or the like. The reflecting mirror 2 shown in the above is the charged particle trajectory 1
Similarly, it is assumed that it is circular, and that the center of curvature of the reflecting mirror 2 substantially coincides with the center of curvature O of the charged particle trajectory 1, and its radius of curvature is R. Therefore, in this example, the reflecting mirror 2 constitutes a concentric circle with a radius of curvature R with the charged particle trajectory 1.

When the reflection ft1!2 and the charged particle trajectory 1 form concentric circles, the synchrotron radiation light (hereinafter referred to as SOR light) emitted from each bunch 6 and 7 in the tangential direction of the charged particle trajectory 1 is reflected. It is reflected by the mirror 2 so as to be in contact with the charged particle trajectory l. Therefore, in this configuration, the SOR light emitted from each bunch 6 and 7 is guided to the pre-extraction port 3 while repeatedly coming into contact with the charged particle trajectory 1. This is a reflection tl! This means that the SOR light emitted at the point of contact between the SOR light reflected at 2 and the charged particle trajectory 1 is all guided to the pre-extraction exit 3 through the same optical path, which improves the utilization efficiency of the SOR destination. can be improved.

The optical storage ring shown in FIG. 1 has a configuration that allows reflected SoR light to interfere with each other, or emitted SOR light and reflected SOR light to emphasize light of a specific wavelength. ing.

In order to cause the above-mentioned interference between the SOR lights and to emphasize the light of a specific wavelength, the curved radius r of the charged particle trajectory 1 and the reflection #J! A special relationship is required between the radius of curvature R and the radius of curvature R of 2.

In the embodiment shown in FIG. 1, an appropriate optical path difference (in this example (corresponding to the time difference), and in order to cause interference, the radius of curvature of the reflecting mirror 2 and the radius of curvature of the charged particle trajectory l are set to certain specific values, which will be described later.

When the radius of curvature of the reflecting mirror 2 and the radius of curvature of the charged particle trajectory 1 are set to the above-mentioned specific values, A on the charged particle trajectory 1
By reflecting the SOR light emitted from the first bunch 6 at a certain time at a point B at a point B on the reflecting mirror 2, it can be made to intersect with the second bunch 7 traveling on the charged particle trajectory 1. .

In this case, it is possible to cause the SOR light from the first bunch 6 and the SOR light emitted from the second bunch 7 to interfere with each other.

This will be explained in more detail below. First, at point A on the charged particle trajectory 1, from the first bunch 6 at time 1
−0, the SOR light is emitted in the tangential direction of the charged particle trajectory 1, passes through the optical path 11, reaches the reflection point B of reflection m2, and after being reflected at this reflection point B, the charged particle Assume that the path reaches point C on trajectory 1. Here, the time required for the SOR light from the first bunch 6 to travel from point A to point C is assumed to be T1.

On the other hand, if the time required for the second bunch 7, which was at the position 1-0 delayed by half a period (dotted line position 7' in Fig. 1), to advance to point C, is T2, then the curvature of the charged particle trajectory 1 is By selecting the radius r and the radius of curvature R of the reflecting mirror 2, T
1 and T2 can be made approximately equal.

Generally, according to the principle of light interference, the optical path difference between the lights emitted from two light sources corresponds to the fundamental wavelength of interference. Further, in this embodiment, this optical path difference corresponds to the time difference between T1 and T2.

Here, the angle formed by the line segment OA connecting the center of curvature O of the charged particle trajectory l and the point A and the line segment OB connecting 0 and the reflection point B is θ
Then, this angle θ is equal to the angle formed by line segments OB and OC. Therefore, the optical path 11 has the same length as the optical path 12. On the other hand, the second bunch 7 is 2
It progresses by ``θ10π''.

Therefore, the following equation can be obtained, where C is the speed of the SOR destination and V is the speed of the second bunch 7.

T1=2rtan (θ)/e (1)T2−(
2rθ+rzrr)/v (2) Normally, when incident light is reflected by a reflecting mirror, the phase of the reflected light is shifted by half of its fundamental wavelength λ with respect to the incident light.

Taking this into consideration, the wavelength λ of the light emphasized by interference is
The following relationship holds true between the radius r of the charged particle trajectory 1 and the radius r of the charged particle trajectory 1.

1 (2rtan (θ)±λ/2)/c(nyr+2
θ)r/v|=m λ/C... (3) (However, n is a positive integer and means the bunch after n, and m
is an integer and represents the harmonic order, and ±λ/2 is a correction term that takes into account the phase shift caused by the reflecting mirror. ) In addition,
Since the phase shift caused by the reflecting mirror may differ depending on the reflecting mirror, the above correction term may generally be expressed as ν. This also applies to other embodiments.

Further, the radius R of the reflecting mirror 2 is given by the following equation.

R=r/cos(θ) −(4) Above formula (3)
If the radius of curvature R of the reflecting mirror 2 is set so as to satisfy (4), the reflected light emitted from the first bunch 6 and reflected at the reflection point B by the reflecting mirror 2 will be reflected from the first bunch 6. It is possible to cause the SOR light emitted from the subsequent bunch to interfere with each other with a specific optical path difference.

If the SOR lights emitted one after another are reflected and interfered in this way, for example, r m0.5 ms R-1.48
At 5847m, the fundamental wavelength λ is approximately 0.20μ as the emitted light.
m light and its riE wave can be obtained.

The above-mentioned optical storage ring is similar to an undulator in that it uses interference, but with an undulator, it is difficult to keep the previous time difference constant when the number of magnetic poles increases. On the other hand, in a photo-storage ring, the electrons are accelerated each time, so the speed of the electrons is constant, and the time difference can be maintained more accurately. Further, although it is difficult to use a strong magnetic field with an undulator, a light storage ring can use a magnetic field of several Teslas, so it is possible to generate a more intense light beam.

Equation (3) above was for the case where the number of bunches was 2, but if we generalize the number of bunches to k and the number of reflections to q, then (3) can be rewritten as follows. I can do it.

|q (2rtan (θ)±λ/2)/c(2nπ/
k+2θq)r/v|=mλ/C...(3') [Example 2] FIG. 2 is a schematic plan view for explaining the principle of a light storage ring according to another example of the present invention. , parts corresponding to those in FIG. 1 are given the same reference numerals. The relationship between the radius of curvature r of the charged particle trajectory 1 and the radius of curvature R of the reflection m2 is different from that in FIG. 1, as will be described later.

In Fig. 1, an example was given in which the SOR light emitted from one bunch interferes with the SOR light emitted from another bunch, but in the example shown in Fig. 2, 17 bunches have a predetermined length. Therefore, the reflected light (first SOR light) that comes out from the head of a bunch and is reflected by reflection #1!2 has a specific optical path difference from the second SOR light that comes out from the tail of the same bunch. to interfere.

In FIG. 2, the head of the bunch 6 is at point A on the charged particle trajectory 1 at time t-0, and after a certain period of time has passed from time 1-0, the tail of the bunch 6 is on the charged particle trajectory 1.
Assume that it is at point C above.

On the other hand, it is assumed that the SOR destination emerging from the head of the bunch 6 at t-0 passes through the optical path l1, is reflected at point B of the reflecting mirror 2, and reaches point C after a time T3 has elapsed.

Assume that the tail of the bunch 6 reaches point C after the elapse of time T4, and if the length of the bunch 6 is L-Lo, then L-
For L shorter than Lo, (1). Similarly to equation (2), T3 and T4 are given by the following equations.

T3-2rtan(φ)/c-(5)T4-(2
rφ+L)/v −C6) Therefore, the wavelength λ that causes interference is set to be the same as lT3±λ/2c−T41−mλ/
C... (7) It can be found as follows. In the above equation, if r - 0.5 m, the length Lo of the bunch is about 3 cm, so the radius R of the reflecting mirror 2 can be about R - 0.55 m or shorter.

At this time, the angle of incidence on the reflecting mirror 2 can be made very large, and the efficiency of reflection, that is, the reflectance can be improved.

In this respect, it is advantageous to amplify light with a shorter wavelength.

Also, although interference can only be caused in this way once, as in the embodiment shown in Figure 1, this interference light is made to intersect with light emitted from another bunch under the same phase conditions. You can also do that. That is, after the interference light is reflected q times, it can be made incident on the head of the next bunch. The conditions in this case are given by q (T3±λ/2c) (n, v+2qθ)r/v−mλ/C (8). Here, it means a bunch after an integer number nIin. That is, since L is an arbitrary number smaller than L0, a solution that satisfies equations (5) to (8) can be found. When rm0.5m, q
-50, 1g of solutions that satisfy equation (8) are found. The reflectance of the reflecting mirror 2 is usually about 99.95%, so if it is reflected 50 times, the reflectance will be about 99.5%.
The decrease in the intensity of reflected light is relatively small.

Note that the above equation (8) is for the case where the number of bunches is 2, but if the number of bunches is generalized to k, equation (8) can be rewritten as follows.

|q(T3 ±λ/2 c) (2 n x / k + 2 q θ) r/v |
=mλ/C... (8') Referring to FIG. 3, a specific example of the structure of the optical storage ring shown in FIGS. 1 and 2 is listed. The pre-storage ring comprises a vacuum vessel 21 and a reflection vt2 arranged inside the vacuum vessel 21, the reflection mirror 2 having the same center of curvature as the charged particle trajectory. The reflecting mirror 2 has a substrate such as SLC and a reflecting surface made of a U plate coated with gold or the like.

This reflective surface has a predetermined curved skewer in the horizontal direction of the figure.
Moreover, it also has a curvature in the vertical direction. This vertical curvature is the SOR. Since light is also emitted radially in the vertical direction, this is to refocus the reflected SOR light on the charged particle trajectory. Specifically, a curvature of rtan(θ) is given in the vertical direction of the reflecting mirror 2.

A light output port 3 is attached to a part of the reflecting mirror 2, and the light extraction port 3 is connected to a light extraction support 22 outside the vacuum container 21 through a hollow tube.

Further, since the reflecting mirror 2 is heated and expanded by the reflection at the SOR destination, the curvature of the reflection m2 may change. In this way, when the radius of curvature changes, the wavelength of the light that causes interference changes with time.

In order to prevent changes in the radius of the skewer due to thermal expansion of the reflector 2, a groove 2 for water cooling is provided on the surface opposite to the reflective surface of the reflector 2.
4 is attached, and this groove portion 24 is connected to the outside of the vacuum container 21 via a pipe 25. Furthermore, the optical storage ring shown in the figure divides the reflected tfl2 into several segments 201 and 202, etc., and each segment 201
and 202 is a piezo chord etc. A vertical fine adjustment device 26 and a radial fine adjustment device 27 using a Viezo element or the like are attached to each segment 201, 202 so that adjustment can be made in the vertical direction and the radial direction of curvature.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the radius of curvature of the reflection point of the SOR light reflection means arranged so as to surround the outer periphery of the orbit of the charged particles is appropriately set. This has the effect of causing interference at the SOR destination and allowing monochromatic SOR light corresponding to a specific wavelength and its harmonic wavelength to be extracted as emitted light.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view for explaining the principle of an optical storage ring according to one embodiment of the present invention, and FIG. 2 is a schematic plan view for explaining the principle of a pre-storage ring according to another embodiment of the present invention. , and FIG. 3 are partial perspective views showing the specific structure of the optical storage ring used in FIGS. 1 and 2. l... Charged particle trajectory, 2... Reflector, 3... Light extraction port, 6... First bunch, 7... Second bunch,
ll... Optical path at the SOR destination. 12... Optical path of reflected light.

Claims (5)

[Claims] (1) By moving a charged particle at a speed close to the speed of light along a trajectory with a predetermined curvature, synchrotron radiation is generated in the tangential direction of the trajectory, and the synchrotron radiation is directed around the outer periphery of the trajectory. A light storage ring that accumulates the synchrotron radiation light within the reflection means by reflecting it with reflection means arranged so as to surround it, and takes out the accumulated synchrotron radiation light as output light via a light extraction means. In this method, monochromatic light having a specific wavelength and its harmonics are produced using at least one of the interference between the synchrotron radiation light and the reflected light of the synchrotron radiation light, and the interference between the reflected lights. A light storage ring that is characterized by its ability to emphasize waves. (2) The optical storage ring according to claim 1, wherein the charged particles form a plurality of bunches and orbit on the orbit.
The optical path is set such that the synchrotron radiation light emitted from one of the bunches at a certain time and the synchrotron radiation light or reflected light generated from the bunch following the bunch interfere with each other with a specific optical path difference. A light storage ring characterized by the following settings. (3) In the optical storage ring according to claim 2, the orbit of the charged particle is circular with an orbit radius r, and the center of curvature of the reflecting means substantially coincides with the center of curvature O of the orbit of the charged particle. , and from one of the bunches, synchrotron radiation light emitted from point A on the orbit at a certain time is reflected at point B on the reflecting means, and C of the orbit of the charged particle is again reflected.
Assuming that the charged particle reaches a point, the orbital radius r of the charged particle and the curvature radius R of the reflecting means are expressed by the following equations (a) and (b).
The optical storage ring is selected so as to satisfy the following: whereby the specific optical path difference between the synchrotron radiation lights can be realized. |(2qθ+2nπ/k)r/v −q(2rtan(θ)±ν)/c| =mλ/c(a) R=r/cos(θ)(b) (However, n is a positive integer, k is the number of bunches, q is a positive integer and the number of reflections, v is the velocity of the charged particle, c is the speed of light, λ is the fundamental wavelength of the interference light, m is an integer and the harmonic order, and θ is the line segment OA. is the angle formed by OB, and ν is a correction term taking into account that the phase of light changes due to the reflecting means). (4) The light storage ring according to claim 1, wherein the charged particles form a plurality of bunches and orbit on the orbit, and each bunch has a leading end and a tail. synchrotron radiation reflected from the
A light storage ring characterized in that an optical path is set so that synchrotron radiation light emitted from the tail of the same bunch interferes with the specific optical path difference. (5) the orbit of the charged particle is circular with an orbit radius r;
The center of curvature of the reflecting means substantially coincides with the center of curvature O of the trajectory of the charged particle, and the synchrotron radiation light emitted from point A at the head of the bunch is directed onto the reflecting means. The radius of curvature R of the reflecting means and the radius of the orbit of the charged particle when the tail of the bunch reaches point C when it is reflected at point B and comes into contact with the charged particle trajectory at point C. In effect, the following equations (c), (d),
The optical storage ring according to claim 4, characterized in that it satisfies (e). |(2rtan(θ)±ν)/c −(2rθ+L)/v|=mλ/c(c) |q(2rtan(θ)±ν)/c −(2nπ/k+2qθ)r/v|=mλ/ c(d)R
= r/cos(θ)(e) (where n is a positive integer, k is the number of bunches, q is a positive integer and the number of reflections, v is the speed of the charged particle, c is the speed of light, and λ is the interference The fundamental wavelength of the light, m is an integer and the harmonic order, θ is the angle formed by the line segments OA and OB, L is an arbitrary length that can be varied up to the maximum length Lb of the bunch, and ν is the phase of the light due to the reflection means. This is a correction term that takes into account changes in the