JP2009043657A - X-ray generator, and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray generator capable of generating an X-ray having intensity higher than that of a conventional one; and its method. <P>SOLUTION: This X-ray generation method includes: a first step of forming an electron beam e by accelerating electrons by using an acceleration device; and a second step of making the electron beam e pass in parallel to a surface of a flat target T at a distance of 10-100 nm from the surface of the flat target T. The X-ray generation method is characterized in that at least a surface layer part of the target T is formed of a substance easily generating an X-ray X by transition radiation by being polarized by interaction with the electron beam e. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray generator, and more particularly to an X-ray generator and a method for generating X-rays by transition radiation.

  Various methods are known for generating X-rays. For example, an X-ray generator using transition radiation generated when high-energy electrons pass through a boundary between substances having different dielectric constants is known. For example, Patent Documents 1 and 3 below disclose an X-ray generator that can output variable-energy X-rays with high directivity using transition radiation. In Patent Documents 1 and 3, as shown in FIG. 7, when a high-energy electron beam passes through a target in which thin films are arranged in multiple layers or different material thin films are alternately stacked, It is disclosed that X-rays are emitted in a conical shape.

Patent Document 2 below has a structure in which thin films (thickness of 0.1 to 10 μm) made of a material having high generation efficiency of transition radiation and thin films made of a substance having a high X-ray transmittance are alternately stacked. The target is disclosed. The cited document 2 also discloses a target having a structure in which a plurality of substances having high generation efficiency of transition radiation are arranged with a donut-shaped spacer 13 interposed therebetween as a conventional technique.
JP-A-10-170699 JP 11-258400 A JP 2001-203096 A

  However, in the above Patent Documents 1 to 3, since the electron beam is incident substantially perpendicular to the surface along the layer of the multilayer target, the region where the transition radiation is generated is narrow, and the X-ray having sufficient intensity depending on the application. There is a problem you can't get. That is, as shown in FIG. 8, X-rays are generated only from a very narrow area (area A indicated by oblique lines) of the target T.

  Accordingly, an object of the present invention is to provide an X-ray generation apparatus and method that can generate X-rays with higher intensity than before.

  The object of the present invention is achieved by the following means.

  That is, the first X-ray generation method according to the present invention includes a first step of accelerating electrons using an acceleration device to form an electron beam, and a distance of 10 nm to 100 nm from the surface of the flat target, A second step of allowing the electron beam to pass in parallel to the surface of the target, and at least a surface layer portion on the surface side of the target is easily polarized by interaction with the electron beam to generate transition radiation It is characterized by being formed by.

  In the second X-ray generation method according to the present invention, an angle of 3 ° or less is formed with respect to the first step of accelerating electrons using an acceleration device to form an electron beam and the surface of the flat target. And a second step of irradiating the surface of the target with the electron beam, and at least a surface layer portion on the surface side of the target is a substance that easily generates transition radiation by being polarized by the interaction with the electron beam. It is characterized by being formed.

  In the first or second X-ray generation method, the target includes a plurality of thin films arranged at a predetermined interval from each other, and the thin film is polarized by interaction with an electron beam. It can be made of a material that easily generates transition radiation.

  In the first or second X-ray generation method, the target has a diffraction grating structure on a surface, and in the first step, the electron beam is allowed to pass through the vicinity of the surface having the diffraction grating structure. Alternatively, the surface having the diffraction grating structure can be irradiated with the electron beam.

  A third X-ray generation method according to the present invention includes a first step of accelerating electrons using an acceleration device to form an electron beam, and a first step of irradiating the surface of a flat target vertically with the electron beam. The target is formed of a material that is easily polarized by interaction with an electron beam to generate transition radiation, and has a plurality of holes having a diameter of nano-order and penetrating in a thickness direction. It is said.

  In any one of the first to third X-ray generation methods, the substance that easily generates transition radiation is formed of one substance selected from the group consisting of carbon, diamond, beryllium oxide, and aluminum oxide. Can be.

  A first X-ray generator according to the present invention includes an accelerator that accelerates electrons and repeatedly circulates a predetermined trajectory to generate an electron beam, and a flat target, and is 10 nm or more from the surface of the target. Passing the electron beam parallel to the surface of the target at a distance of 100 nm or less, and polarizing part of the linear region of the surface layer portion on the surface side of the target by interaction with the electron beam; It is characterized by generating transition radiation.

  A second X-ray generator according to the present invention includes an acceleration device that generates electrons by accelerating electrons and repeatedly orbiting a predetermined trajectory, and a flat target, and the surface of the target is The surface of the target is irradiated with the electron beam so as to form an angle of 3 ° or less, and a part of the linear region of the surface layer portion on the surface side of the target is polarized by interaction with the electron beam. It is characterized by generating transition radiation.

  According to the present invention, since the electron beam passes in the vicinity of the target surface in parallel or is incident on the target surface at a relatively small incident angle, the region where the transition radiation is generated becomes wider than before, and is higher than before. Intense X-rays can be generated.

  Further, by using a target having a laminated structure and irradiating an electron beam substantially parallel to the laminated structure, X-rays with higher intensity can be generated.

  Further, by using a porous target and irradiating an electron beam substantially perpendicularly to the surface thereof, it is possible to generate higher-intensity X-rays.

  Also, by forming a diffraction grating structure on the surface of the target, it is possible to generate monochromatic X-rays with higher intensity than before, and by adjusting the period of the diffraction grating structure, it is possible to generate monochromatic EUV light. Is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a plan view showing a schematic configuration in the vicinity of a target of an X-ray generator according to an embodiment of the present invention. In the present X-ray generator, an acceleration device (not shown) such as a synchrotron for accelerating and revolving around electrons along a predetermined trajectory to form an electron beam e, and a target T irradiated with the electron beam e And support means (not shown) for arranging the target T at a predetermined position. In this X-ray generator, the target T is disposed in the vicinity of the trajectory of the electron beam e. As a result, transition radiation is generated at a portion of the surface of the target T where the electron beam e passes in the vicinity, and X-rays are emitted in a predetermined direction.

  FIG. 2 is an enlarged cross-sectional view of the target T of FIG. Note that FIG. 2 is a conceptual diagram, and the ratios in the vertical and horizontal directions are not the same, and are not drawn in a linear ratio in each direction (the same applies to FIG. 3 and subsequent figures). The target T is made of a material that easily generates transition radiation, for example, a material that can generate dielectric polarization having a relatively high dielectric constant, such as germanium, gallium, silicon, carbon, diamond, beryllium, and aluminum (alumina). It is formed in a flat plate shape with a thickness of. The electron beam e is allowed to pass along the surface of the target T in the vicinity of the surface, for example, a range where the distance d1 from the surface is 10 to 100 nm (nanometers). At this time, polarization due to the electric field generated by the electron beam e is generated in the surface layer portion of the target T (in FIG. 2, the region above the broken line and having a very thin thickness from the surface), and X-rays are emitted (transition radiation). ) Therefore, since X-rays by transition radiation are generated from a linear region along the electron beam e on the target surface, the intensity (photon number) is higher than that in the conventional case where the electron beam is irradiated perpendicularly to the target surface. X-rays can be generated.

  3 is a cross-sectional view in which the same target T as in FIG. 2 is arranged so that the electron beam e is incident on the surface of the target T at a predetermined angle θ. Here, the angle θ is in a range of 0 <θ <3 (°). Also in this case, as in the case of FIG. 2, X-rays due to transition radiation are generated from the portion of the target surface where the electron beam e is close. Since the incident angle θ is sufficiently small, the distance between the electron beam e and the target surface is such that the transition radiation is generated, that is, a linear region of the target surface that is 10 to 100 nm (the region indicated by hatching in FIG. 3), Since X-rays are generated, it is possible to generate X-rays with a stronger intensity than before.

  Since transition radiation is generated in the surface layer portion of the target T, the entire target T does not have to be formed of a substance that easily generates transition radiation. For example, a layer of a material that easily generates transition radiation (hereinafter also referred to as a transition radiation material layer) having a thickness of 3 nm or less may be formed on the surface of a thin membrane having a thickness of 1 μm or less.

  Further, as shown in FIG. 4, the target T1 may be formed by arranging a plurality of thin film substances that are likely to generate transition radiation in parallel. 4A is a cross-sectional view taken along the electron beam, and FIG. 4B is a cross-sectional view perpendicular to FIG. In FIG. 4, three transitional radiation material layers U are formed on the membrane B with spacers S formed at both ends interposed therebetween. With the spacer S, each of the three transitional radiation material layers U is arranged in parallel at a predetermined interval. If this is arranged in an electron accelerator (for example a synchrotron), the two intermediate layers V between the three transition emitter layers U become vacuum layers. Here, the transitional radiation material layer U is a material that can cause dielectric polarization having a relatively large dielectric constant, such as germanium, gallium, silicon, carbon, diamond, beryllium, and aluminum (alumina), as described above. .

  When an electron beam e having a predetermined spread is incident on the transition radiation material layer U in parallel, X-rays due to transition radiation are generated from the surfaces of the plurality of transition radiation material layers U. Accordingly, it is possible to generate X-rays with a stronger intensity than those shown in FIGS. Instead of forming the intermediate layer V as a vacuum layer, the intermediate layer V may be formed of a material having a large difference in dielectric constant from the transition radiation material layer U. For example, when carbon is used as the transition radiation material layer U, the intermediate layer V can be made of lead (Pb), gold (Au), platinum (Pt), magnesium (Mg), gallium (Ga), or the like. . Furthermore, it is desirable to select the transition radiation material layer U and the intermediate layer V in consideration of the energy of light generated by the transition radiation. For example, assuming transition radiation with a light energy of 100 eV and using carbon as the transition radiation material layer U, the intermediate layer V is more gold than lead (Pb), magnesium (Mg), and gallium (Ga). Au) and platinum (Pt) are suitable.

  FIG. 5 is a drawing showing a flat target (hereinafter referred to as a porous target) T2 having a large number of holes penetrating in a direction substantially perpendicular to the surface, where (a) is a front view and (b) is a front view. It is sectional drawing. In the lower right portion of FIG. 5A, a part of the porous portion is shown in an enlarged manner. The porous target T2 is formed of a substance that has a through-hole having a diameter of the order of nm and is likely to generate transition radiation. The porous structure can be formed by, for example, anodizing Al in an acidic electrolytic solution. When the electron beam is irradiated onto the porous portion substantially perpendicularly to the surface of the porous target T2, X-rays due to transition radiation are generated as in FIG.

  In the above, although the generated X-ray is a continuous spectrum, as shown in FIG. 6, a monochromatic X-ray can be generated by forming a diffraction grating structure on the surface of the target. In FIG. 6, parallel uneven shapes are formed on the surface of the target T3 at a constant period. When the electron beam e is allowed to pass through the vicinity of the surface of the target T3 where the concavo-convex shape is formed (distance of 10 to 100 nm), the surface layer portion of the convex portion (in FIG. 6, the thickness that is extremely thin from the surface above the broken line) Region) is polarized, and X-rays are generated by transition radiation. At this time, if the interval between adjacent convex portions is λ, a monochromatic X-ray having a wavelength λ can be generated. For example, if λ = 13.5 (nm), monochromatic EUV light having a wavelength of 13.5 nm can be generated. In FIG. 6, similarly to FIG. 3, the electron beam e may be applied to the surface on which the diffraction grating structure is formed so as to form an angle θ (0 <θ <3 (°)).

  As mentioned above, although this invention was demonstrated using embodiment, this invention is not limited to above-described embodiment, It can add and implement various changes, These are also contained in the technical scope of this invention. It is.

It is a top view which shows schematic structure of the target vicinity of the X-ray generator which concerns on embodiment of this invention. It is sectional drawing which expands and shows the target of FIG. FIG. 3 is a cross-sectional view in which the same target as in FIG. 2 is arranged such that an electron beam is incident on the surface of the target at a predetermined angle. It is sectional drawing which shows the target formed by arrange | positioning the thin film substance which is easy to generate | occur | produce transition radiation based on embodiment of this invention in parallel. It is drawing which shows the flat target which has many through-holes based on embodiment of this invention, (a) is a front view, (b) is sectional drawing. It is sectional drawing which shows the target with which the diffraction grating was formed in the surface based on embodiment of this invention. It is a perspective view which shows the structure of the target vicinity in the X-ray generator by the conventional transition radiation. It is sectional drawing which shows the place where transition radiation generate | occur | produces in the target used with the conventional X-ray generator.

Explanation of symbols

T, T1, T2, T3 Target U Transition radiation layer V Intermediate layer X X-ray e Electron beam

Claims (8)

A first step of accelerating electrons using an accelerator to form an electron beam;
A second step of allowing the electron beam to pass in parallel to the surface of the target at a distance of 10 nm to 100 nm from the surface of the flat target,
An X-ray generation method, wherein at least a surface layer portion on the surface side of the target is formed of a substance that is easily polarized by interaction with an electron beam to generate transition radiation. A first step of accelerating electrons using an accelerator to form an electron beam;
And a second step of irradiating the surface of the target with the electron beam so as to form an angle of 3 ° or less with respect to the surface of the flat target.
An X-ray generation method, wherein at least a surface layer portion on the surface side of the target is formed of a substance that is easily polarized by interaction with an electron beam to generate transition radiation. The target includes a plurality of thin films disposed at a predetermined interval from each other,
The X-ray generation method according to claim 1, wherein the thin film is formed of a material that is easily polarized by interaction with an electron beam to generate transition radiation. The target has a diffraction grating structure on its surface;
The said 1st step WHEREIN: The said electron beam is allowed to pass through the vicinity of the surface which has the said diffraction grating structure, or the said electron beam is irradiated to the surface which has the said diffraction grating structure. X-ray generation method. A first step of accelerating electrons using an accelerator to form an electron beam;
A second step of irradiating the surface of the flat target with the electron beam perpendicularly,
The target is
It is made of a material that is easily polarized by interaction with the electron beam to generate transition radiation.
An X-ray generation method comprising a plurality of holes having a diameter of nano-order, penetrating in a thickness direction.   6. The material that easily generates transition radiation is formed of one material selected from the group consisting of germanium, gallium, silicon, carbon, diamond, beryllium, and aluminum. The X-ray generation method according to any one of the above. An acceleration device for accelerating electrons and repeatedly orbiting a predetermined orbit to generate an electron beam;
With a flat target,
Passing the electron beam parallel to the surface of the target at a distance of 10 nm to 100 nm from the surface of the target;
An X-ray generator, wherein a part of a linear region of a surface layer portion on the surface side of the target is polarized by interaction with an electron beam to generate transition radiation. An acceleration device for accelerating electrons and repeatedly orbiting a predetermined orbit to generate an electron beam;
With a flat target,
Irradiating the surface of the target with the electron beam so as to form an angle of 3 ° or less with respect to the surface of the target;
An X-ray generator, wherein a part of a linear region of a surface layer portion on the surface side of the target is polarized by interaction with an electron beam to generate transition radiation.

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