JP4982674B2 - X-ray generator - Google Patents

Description

  In the present invention, an electron generating means for generating electrons and an X-ray target supported by a support member are arranged in a vacuum tube, and X-rays generated by irradiating the X-ray target from the electron generating means with a predetermined position The present invention relates to an X-ray generator in which X-ray guide means for guiding is arranged outside a vacuum tube.

In recent years, X-ray analyzers are used for the analysis of animals and plants or minerals, or the analysis or quality control of electronic components (see, for example, Patent Document 1). The X-ray analyzer includes an X-ray generator for irradiating a sample with X-rays. FIG. 5 is a diagram showing an example of an X-ray generator. The X-ray generator includes a filament 70 that generates electrons, an X-ray target 62, and an X-ray guide tube (X-ray guide means) that guides X-rays generated by irradiating electrons from the filament 70 to the X-ray target 62. ) 80.
JP 2000-212299 A

  The X-ray target 62 and the filament 70 are disposed in the vacuum tube 68, and the X-ray guide tube 80 is disposed outside the vacuum tube 68 with the beryllium window 72 interposed therebetween. The diameter of the X-ray guide tube 80 is about 0.1 mm, and the distance from the X-ray target 62 to the X-ray guide tube 80 is about 30 mm. Therefore, only a part of the X-rays generated by the X-ray target 62 is guided to the sample by the X-ray guide tube 80, and there is a problem that the generated X-rays are not used effectively.

  The present invention has been made in view of such circumstances, and is provided with a recess recessed inwardly in a vacuum tube, and an X-ray guide means is inserted into the recess so that X-rays generated in an X-ray target can be generated. An object of the present invention is to provide an X-ray generator capable of improving luminance by condensing or constricting with an X-ray guide means (hereinafter referred to as condensing).

  Further, in the present invention, the X-ray target is attached to the protrusion of the support member, so that the electrons are focused on the X-ray target and collided to efficiently generate the X-ray generated by the X-ray target. Another object of the present invention is to provide an X-ray generator that can improve brightness by condensing light with a guide means.

  Further, in the present invention, by adopting a configuration in which the X-ray target is attached to the projection portion having a spherical surface, electrons are well focused and collided with the X-ray target, and the X-ray generated by the X-ray target is further reduced. Another object of the present invention is to provide an X-ray generator that can improve luminance more efficiently by condensing light efficiently with an X-ray guide means.

Another object of the present invention is to provide an X-ray generator that can efficiently dissipate heat from the X-ray target by attaching the X-ray target to the protrusion of the support member via diamond. To do.

  In addition, the present invention provides an X-ray generator capable of reducing the size of the X-ray generator by disposing the X-ray guide means and the electron generating means so as to face the protrusion of the support member. For other purposes.

  Another object of the present invention is to provide an X-ray generator that can be miniaturized by using a cold emitter and an electrode for generating electrons from the cold emitter as electron generating means.

In the X-ray generator according to the present invention, an electron generating means for generating electrons and an X-ray target supported by a support member are arranged in a vacuum tube, and the X-ray target is irradiated with electrons from the electron generating means. In an X-ray generator in which X-ray guide means for guiding generated X-rays to a predetermined position is disposed outside the vacuum tube, the electron generation means generates a cold emitter using carbon nanotubes and electrons from the cold emitter. The support member has a projection, the X-ray target is attached to the projection via a diamond, and the X-ray guide means is formed in a tubular shape and is incident on one end Of the X-rays, X-rays whose incident angle with respect to the inner surface is smaller than the critical angle of total reflection are condensed by total reflection on the inner surface and irradiated to the predetermined position from the other end. Configuration and has become in that, said X-ray guide means and the electron generating means is arranged to face to the X-ray target, the tube is provided with a recess recessed inwardly, the X-ray to the recess One end of the guide means is inserted.

The X-ray generator according to the present invention is characterized in that the combined surface shape of the X-ray target attached to the protrusion via the protrusion and diamond is spherical.

In the X-ray generator according to the present invention, an electron generating means for generating electrons and an X-ray target supported by a support member are arranged in a vacuum tube, and the X-ray target is irradiated with electrons from the electron generating means. In the X-ray generator in which X-ray guide means for guiding the generated X-rays to a predetermined position is arranged outside the vacuum tube, the support member has a protrusion, and the X-ray target is attached to the protrusion via a diamond. The X-ray guide means is formed in a tubular shape by totally reflecting, on the inner surface, X-rays whose incident angle with respect to the inner surface is smaller than the critical angle of total reflection among the X-rays incident on one end. The X-ray guide means and the electron generating means are arranged so as to face the X-ray target, and the electron generating means is configured to collect light and irradiate the predetermined position from the other end. , Characterized in that it comprises a cold emitter formed by using the arranged carbon nanotubes to the end periphery of the X-ray target side of the X-ray guide means and an electrode to generate electrons from the cold emitter.

In the present invention, since the X-ray guide means is inserted into the inwardly recessed portion of the vacuum tube, the distance between the X-ray target and the X-ray guide means is reduced, the solid angle is increased, and the X-ray target is generated. The X-rays can be efficiently condensed by the X-ray guide means, and the luminance can be improved. The X-ray guide means includes an X-ray guide tube that collects X-rays and directs them to the irradiation region, and a collimator that restricts the solid angle and guides X-rays to the irradiation region. Including.

In the present invention, the support member has a protrusion, and an X-ray target is attached to the protrusion. The distribution of the electric lines of force around the protrusion is a substantially concentric distribution according to the shape of the protrusion, and the electrons irradiated from the electron generating means are focused in the central direction of the distribution. For example, when the surface of the protruding portion is spherical, the distribution of electric lines of force around the protruding portion is a concentric spherical distribution, and the electrons emitted from the electron generating means are converged toward the center of the concentric spherical surface. It is possible to focus the electrons irradiating the X-ray target, efficiently guide the X-ray generated by the X-ray target, and to easily reduce the X-ray beam diameter. Further, by focusing the electron irradiation spot, the amount of current can be reduced, and the power supply unit can be downsized. Therefore, it becomes easy to reduce the size of the entire generator. Furthermore, since the protrusion protrudes inside the vacuum tube, the X-ray target is disposed inside the vacuum tube, and the distance from the X-ray guide means is reduced. Therefore, X-rays generated by the X-ray target can be efficiently condensed by the X-ray guide means, and the luminance can be improved.

In the present invention, since the X-ray target is attached to the protrusion of the support member via diamond having high thermal conductivity, the heat generated in the X-ray target can be efficiently released to the support member. Heat radiation of the X-ray target can be performed efficiently.

In the present invention, when the X-ray guide means and the electron generation means for guiding the generated X-rays to a predetermined position are arranged so as to face the protrusion of the support member, the electron generation means is supported in the vicinity of the X-ray guide means. Is possible. By supporting the electron generating means in the vicinity of the X-ray guide means, the X-ray generator can be reduced in size.

In the present invention, since a cold emitter (cold cathode) and an electrode for generating electrons from the cold emitter are used as the electron generating means, unlike the case of using a tungsten filament, it is not necessary to apply heat. Since heat is not applied, a cooling fan or the like is unnecessary, and the X-ray generator can be downsized. Further, the use of a cold emitter can increase the brightness.

According to the present invention, the X-rays generated by the X-ray target can be efficiently condensed by the X-ray guide means and the luminance can be improved.

According to the present invention, the electrons irradiated to the X-ray target can be focused, and the X-ray generated by the X-ray target can be efficiently condensed by the X-ray guide means, thereby improving the luminance.

According to the present invention, the heat radiation of the X-ray target can be efficiently performed.

According to the present invention, the X-ray generator can be reduced in size.

  Hereinafter, the case where the X-ray generator of the present invention is used in an X-ray analyzer will be described as an example. The X-ray generator of the present invention is not limited to the X-ray analyzer, and can be used for any apparatus that generates X-rays.

  FIG. 1 is a partial cross-sectional view showing a configuration example of an X-ray generator according to the present invention. The X-ray generator 10 is disposed above the sample stage 36 and irradiates the sample 38 placed on the sample stage 36 with X-rays. Reference numeral 30 denotes an X-ray guide tube (X-ray guide means) made of silica glass, and the opening on the tip side is disposed above the sample stage 36. The X-ray guide tube 30 has a tubular shape such as a cylinder having a diameter of about 0.1 mm. For example, a semi-cylindrical shape may be used. Although not shown, a semiconductor detector for detecting fluorescent X-rays generated by irradiating the sample 38 with X-rays is provided so as to face the sample stage 36.

  The base side of the X-ray guide tube 30 is inserted into a recess 28 that protrudes inside the vacuum tube 18. The vacuum tube 18 is kept at a high vacuum by a getter pump 19. FIG. 2 is a partial cross-sectional view of the bottom portion of the recess 28. A beryllium window 22 is provided at the bottom of the recess 28, and the opening on the base side of the X-ray guide tube 30 faces the beryllium window 22. A carbon nanotube (cold emitter: cold cathode) 20 is disposed at the center and outer periphery of the upper side (inside the vacuum tube 18) of the beryllium window 22, and an extraction electrode 24 is disposed further above (X-ray target 12 side). Generation means are configured. Note that the carbon nanotubes 20 can be arranged not only in the center on the upper side of the beryllium window 22 but only in the periphery of the outer periphery. In this case, the X-rays that are incident on the X-ray guide tube 30 are not blocked by the carbon nanotubes 20 arranged at the center, so that the X-rays are efficiently incident.

  As shown in FIG. 1, the X-ray target 12 is disposed above the extraction electrode 24. The X-ray target 12 is attached to the tip (projection) of a bar-shaped copper support member 14. The front end side of the support member 14 is disposed in the vacuum tube 18, and the base side of the support member 14 is inserted into the oil bath 16. FIG. 3 is a partial cross-sectional view of the distal end portion of the support member 14. The tip surface of the support member 14 is spherical.

  The X-ray target 12 is attached to the tip of a copper support member 14 through a diamond 40. The X-ray target 12 is fixed to the diamond 40 through the buffer layer 42 by vapor deposition or sputtering. As the buffer layer 42, for example, when the X-ray target 12 is rhodium, tantalum is used, and when the X-ray target 12 is tungsten, the buffer layer 42 may not be provided. The diamond 40 is fixed to the copper support member 14 by silver brazing in a vacuum. It is preferable to provide a thin film of titanium or the like as the buffer layer 44 for differential thermal expansion between the support member 14 and the diamond 40. The heat of the X-ray target 12 is released to the oil bath 16 through the high thermal conductivity diamond 40 and the copper support member 14.

  A power supply E1 is connected to the extraction electrode 24, and a high voltage for accelerating electrons generated from the carbon nanotubes 20 is applied between the extraction electrode 24 and the X-ray target 12 by the power supply E2. ing. Electrons 26 generated from the carbon nanotubes 20 by the voltage applied to the extraction electrode 24 are accelerated by the electric field applied between the X-ray target 12 and the extraction electrode 24 and collide with the X-ray target 12. At this time, the tip of the support member 14 has a hemispherical shape, and as shown by the broken line in FIG. 1 or 3, the electric force lines around the tip become a spherical shape concentric with the tip, and the accelerated electrons are directed toward the center of the spherical surface. For example, a spot having a diameter of 1 μm or the like can be easily focused on the X-ray target 12. In addition, since the electrons are easily focused, the power source E2 can be downsized.

  When X-rays are generated by collision of electrons with the X-ray target 12, the generated X-rays travel to the X-ray guide tube 30, and the incident angle with respect to the inner surface of the X-ray guide tube 30 is smaller than the critical angle of total reflection Then, the light is condensed by being totally reflected from the inner surface, and is irradiated onto the sample 38 on the sample stage 36. At that time, when the electrons are focused on the X-ray target 12 with a small diameter, high-energy X-rays are collected more efficiently. Further, since the X-ray guide tube 30 is inserted into the recess 28 of the vacuum tube 18, the distance from the X-ray target 12 to the X-ray guide tube 30 is reduced to about 7 mm, and X-rays can be collected efficiently. . Therefore, an X-ray beam having a high brightness and a small diameter can be realized. Since the brightness of X-rays is increased, sufficient intensity can be obtained even if X-rays are condensed to a diameter of 1 μm, and the spatial resolution in two-dimensional measurement can be dramatically improved from the current 10 μm to 1 μm. . The fluorescent X-rays generated by irradiating the sample 38 with X-rays are detected by the above-described semiconductor detector (not shown). Then, the composition of the sample 38 can be obtained by analyzing the signal of the semiconductor detector with an analyzer (not shown).

  Further, the X-ray generator can be miniaturized by inserting the X-ray guide tube 30 into the concave portion 28 of the vacuum tube 18. Furthermore, by arranging the carbon nanotube 20 and the extraction electrode 24 in the vicinity of the opening on the base side of the X-ray guide tube 30, the X-ray generator can be reduced in size. Since the X-ray generator is miniaturized, scanning can be performed by moving the X-ray generator itself. Therefore, it becomes possible to measure a large sample or a biological sample. In particular, it becomes possible to perform fluorescent X-ray analysis on the human body, which has been impossible until now in the medical field.

In the above-described embodiment, a LaB ₆ crystal can be used as the cold emitter (20) instead of the carbon nanotube. Further, the electrons accelerated between the cold emitter (20) and the X-ray target 12 are focused on the X-ray target 12 by an electric field corresponding to the tip shape of the support member 14. It is also possible to use a lens. Further, the X-ray target 12 uses tungsten, rhodium, or the like, and can be implanted or mechanically bonded to a metal such as copper or silver having good thermal conductivity. It is also possible to cool the oil bath 16 using a fan, or to cool the copper or silver itself without using the oil bath 16 to release heat. Furthermore, when heat dissipation is good, it is possible not to use diamond between the X-ray target 12 and copper or silver.

  In the embodiment described above, it is of course possible to use a negatively biased filament instead of the carbon nanotube. Further, in the case of the structure, heat can be released by water cooling without using the oil bath 16. FIG. 4 is a partial cross-sectional view showing a configuration example of the X-ray generator according to the present invention. The support member 15 includes a pipe 50 for water cooling. A filament 21 is disposed above the beryllium window 22 at the bottom of the recess 28, and an extraction electrode 25 is disposed further above. The X-ray guide means is preferably an X-ray condensing means such as an X-ray guide tube, but an appropriate X-ray guide member such as a collimator can be used instead.

It is a fragmentary sectional view showing the example of composition of the X-ray generator concerning the present invention. It is a fragmentary sectional view of the bottom part of the crevice of an X-ray generator. It is a fragmentary sectional view of the front-end | tip part of the supporting member of a X-ray generator. It is a fragmentary sectional view showing the example of composition of the X-ray generator concerning the present invention. It is a figure which shows the example of the conventional X-ray generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 X-ray generator 12 X-ray target 14 Support member 16 Oil bath 18 Vacuum tube 20 Carbon nanotube 21 Filament 22 Beryllium window 24, 25 Extraction electrode 26 Electron 30 X-ray guide tube 36 Sample stage 38 Sample 40 Diamond 42, 44 Buffer layer 50 Water cooling pipe

Claims (3)

An X-ray target that generates electrons and an X-ray target supported by a support member are arranged in a vacuum tube, and guides X-rays generated by irradiating the X-ray target from the electron generating means to a predetermined position. In the X-ray generator in which the guide means is arranged outside the vacuum tube,
The electron generating means comprises a cold emitter using carbon nanotubes, and an electrode for generating electrons from the cold emitter,
The support member has a protrusion, and the X-ray target is attached to the protrusion via a diamond,
The X-ray guide means is formed in a tubular shape, and collects X-rays having an incident angle with respect to the inner surface smaller than the critical angle of total reflection among the X-rays incident on one end by total reflection on the inner surface, It is configured to irradiate the predetermined position from the end,
The X-ray guide means and the electron generation means are arranged to face the X-ray target,
The vacuum tube includes a recess recessed inward,
An X-ray generator, wherein one end of the X-ray guide means is inserted into the recess. 2. The X-ray generator according to claim 1, wherein a surface shape of the X-ray target attached to the protrusion via the protrusion and diamond is spherical. An X-ray target that generates an electron and an X-ray target supported by a support member are arranged in a vacuum tube, and guides the X-ray generated by irradiating the X-ray target from the electron generating means to a predetermined position. In the X-ray generator in which the guide means is arranged outside the vacuum tube,
The support member has a protrusion, and the X-ray target is attached to the protrusion via a diamond,
The X-ray guide means is formed in a tubular shape, and collects X-rays having an incident angle with respect to the inner surface smaller than the critical angle of total reflection among the X-rays incident on one end by total reflection on the inner surface, It is configured to irradiate the predetermined position from the end,
The X-ray guide means and the electron generation means are arranged to face the X-ray target,
The electron generating means includes a cold emitter using carbon nanotubes arranged around an end portion on the X-ray target side of the X-ray guide means, and an electrode for generating electrons from the cold emitter. A featured X-ray generator.

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