RU26678U1 - DEVICE FOR OBTAINING X-RAY RADIATION OF INCREASED INTENSITY - Google Patents

Description

Device for obtaining x-rays of high intensity

The utility model relates to means for producing x-ray radiation, in particular to means intended for use in the study and testing of substances, materials or devices.

It is known to use synchrotrons or storage rings to obtain high-intensity X-rays (see: Synchrotron radiation. Edited by K. Kunts. Moscow, Mir Publishing House, 1981, pp. 80 - 89 1). In this case, from the very wide spectrum of synchrotron radiation, the necessary spectral band in the X-ray range is distinguished. However, synchrotron radiation sources, including storage rings, are the most complex capital structures, the cost of which reaches hundreds of millions of dollars. So, storage rings, the emission spectrum of which includes the x-ray range, have a diameter of at least 50 m (1, p. 80).

At the same time, until recently, synchrotron radiation sources were practically the only type of sources that made it possible to obtain a spectral density of narrowly directed x-ray radiation sufficient for research and testing in the required operating range.

The situation changed with the advent of x-ray capillary lenses using the phenomenon of total external reflection (V.A. Arkadyev, A.I. Kolomiytsev, M.A. Kumakhov, etc. Broadband X-ray optics with a large angular aperture. Uspekhi Fizicheskikh Nauk, 1989, Volume 157 , Issue 3, pp. 529-537 2), subsequently crawling to fame as Kumakhov lenses (see

US patent No. 5,175,755, publ. 29.12.92 3 et al.). Due to the focusing properties of the Kumakhov liis, the interactions of a relatively low-power source can be significantly increased. Realizing this opportunity, the known device (US patent. No. 5,570,408, publ. 10/29/96 4) contains an x-ray tube that creates diverging x-ray radiation, and an x-ray lens in the form of a set of curved channels using multiple external external reflection of x-ray radiation from their walls. The latter is installed and made with the possibility of capturing part of the divergent beam of radiation of the x-ray tube and converting it into quasi-parallel or focused. According to the calculations given in the international application PCT / RU 00/00324 (international publication WO 02/12871 of 02/14/2002) 5) using such a device, an intensity comparable to the intensity of the x-ray radiation at the output of the synchrotron source can be achieved.

Known device 4 is closest to the proposed.

The use of an x-ray tube in said known device involves combining the focal spot of its target with the input focus of the x-ray lens (the point of intersection of the extensions of the axial lines of the lens channels located on the extension of its longitudinal axis). Moreover, the capabilities of the lens in the concentration of divergent radiation of the x-ray tube are effectively used only in the case of a quasi-point focal spot of the source, when its size is comparable to the size of the input focal region of the lens in a plane perpendicular to the longitudinal axis of the lens. The possibility of increasing the intensity of the output radiation of the device by increasing the intensity of the radiation emanating from a focal spot of such small dimensions is limited by the thermal strength of the target material. If, however, to prevent the destruction of the target in the focal spot zone, the size of the latter is increased, then some of its elements will not be able to participate in the formation of the output radiation of the device, since the radiation of these elements will not be captured by the lens. In the known device, in particular, satisfactory pairing of the x-ray lens and the x-ray tube with a target having a focal spot in the form of a dash (linear focus) cannot be ensured.

The proposed utility model is aimed at obtaining a technical result, which consists in increasing the radiation intensity at its output by efficiently using the radiation of the focal spot of the target of the x-ray tube, which has finite dimensions, including, significantly, the dimensions of the focal region of the x-ray lens in the size of the input focal region of the lens in a plane perpendicular to the longitudinal axis of the lens.

For this, the proposed device, like the one closest to it 4 mentioned above, contains an x-ray tube forming a diverging x-ray beam, and an x-ray lens mounted and configured to capture a part of the diverging beam of the x-ray tube and converting it into quasi-parallel or focused.

In contrast to the known device, in the proposed device, the x-ray tube is made with a focal spot of the target, the size of which exceeds the size of the focal region of the x-ray lens in a plane perpendicular to the longitudinal axis of the lens, and the x-ray tube is mounted so that the focal spot of its target is offset from the input focus x-ray lens along the longitudinal axis of the x-ray lens.

The focal spot of the target of the x-ray tube should preferably be within the solid angle formed by the extensions of the channels of the x-ray lens towards the exit window of the x-ray tube. This solid angle consists of two parts symmetrical with respect to the input focus of the x-ray lens; the part located between the input fossus and the input end of the x-ray lens is usually called the capture angle.

The optimum is the mutual arrangement of the x-ray tube and the x-ray lens, in which the focal spot of the target of the x-ray tube is completely located within the specified solid angle and reaches its boundaries with its peripheral points. In this case, all elements of the focal spot of the target of the x-ray tube and all channels of the x-ray lens, including peripheral ones farthest from the longitudinal axis, are involved in the formation of the output radiation of the device.

The mixing of the focal spot of the target of the x-ray tube relative to the input focus of the x-ray focus lens is possible within any of the named parts of the indicated solid angle, i.e. both in the direction of approaching the input end of the lens, and in the direction of moving away from it.

The target of the x-ray tube may have, in particular, a linear focus. In this case, the orientation of the linear focus is possible both orthogonal and inclined with respect to the longitudinal axis of the x-ray lens.

The proposed utility model is illustrated by drawings:

FIG. 1 and FIG. 2 shows schematic images of two types of devices with x-ray lenses in the absence of a shift in the focal spot of the target of the x-ray tube relative to the input focus of the lens;

-Fig. 3 and FIG. Figure 4 illustrates the operation of devices with two types of x-ray lenses at different mixtures: focal spot of the target of the x-ray tube relative to the input focus of the lens;

-Fig. 5 and FIG. 7 illustrates the operation of devices with two types of x-ray lenses using a linear focus x-ray tube;

FIG. 6 shows the ability to control the cross-sectional shape of a quasi-parallel output beam using an X-ray tube with a linear focus;

- in FIG. 8 and FIG. 9 shows the use of two types of x-ray lenses in a device with an inclined position of the linear focus of the x-ray tube relative to the longitudinal axis of the lens.

X-ray lenses used both in the proposed device and in the closest known device — lens 1 for focusing the diverging x-ray radiation generated by source 2 and lens 3 for converting said radiation to quasi-parallel — are shown respectively in FIG. 1 and FIG. 2. Both lenses contain multiple channels 4 for transporting x-ray radiation using the phenomenon of multiple total external reflection. Lens 1 is generally barrel-shaped, i.e. tapers to both ends - input (receiving) 5 and output 6. Lens 3 has a half-barrel shape and tapers only to the input end 5. The radiation flux from the output end 6 of the lens 1 converges in the vicinity of the point 7 of the intersection of the axial lines of the channels 4 - the output focus of the lens . The radiation flux 8 from the output end 9 of the lens 3 is quasi-parallel. The axial lines of the extensions of the channels 4 of both lenses 1 and 3, emerging from their input ends 5 toward the x-ray source 2, converge at point 10, the input focus of the lens. The foci 7, 10 are located on the longitudinal axis 11 of the lens 1.3.

For the designation of x-ray lenses of the two types mentioned, the terms “full lens and” half-lens, respectively, have become widespread. The corresponding terminology is used below in the description of the proposed device; in cases where one of the two named types is not meant, the terms "lens or" x-ray lens are used.

Modern x-ray lenses are obtained by the technology of manufacturing monolithic lenses in which (as conventionally shown in Fig. 1 and Fig. 2) the walls of adjacent channels 4 for transporting radiation are in contact with each other along the entire length, and the channels themselves have a variable cross-section along the length, varying by the same law as the full cross section

lenses (VMAndreevsky, MVGubarev, P.LZhidkin, MAKumakhov, AVNoskin, I.Yu. Ponomarev, ICh.Z.Ustok. X-ray waveguide system with a variable crosssection of the sections. The IV-th All-Union Conference on Interaction of Radiation with Solids. Book of Abstracts (May 15-19, 1990, Elbrus settlement, KabardinoBalkarian ASSR, USSR, pp. 177-178) 6. The progressive direction in the technology of manufacturing monolithic lenses is the technology of so-called integral lenses, which provides obtaining lenses with channels whose diameter and, accordingly, the size of the focal region in the transverse direction can be fractions of a micron (international application PCT / RU 00/00206, international publication WO 01/29845 of 26. 04.2001 US patent No. 6,271,534, published on 07/07/2001 8) Therefore, the use of the latest generation 4 lenses in the known device is effective only in combination with microfocus x-ray tubes. With a large focal spot 12 of the target of the x-ray tube 2 lens, focus 10 of which is not offset relative to focal spot, captures the radiation of only part of the elements of this spot that are within the focal region of the lens. The size of this region in the transverse direction, as already noted, is of the order of the transverse size d of the lens channels (more accurate is the estimate d + 2 / (9cg, where vsr is the critical angle of total external reflection, depending on the energy of the radiation used and the material of the walls of the radiation transport channels ; / - the focal length of the lens from the input side - the distance between the focus 10 and the input end 5, see Fig. 1 and Fig. 2). For the radiation of the elements of the focal spot outside the focal region of the lens, the condition of complete external pressure, and this radiation, having got to the inputs of the channels 4 for transporting radiation, does not propagate through them.

In the proposed device can be used and non-focus x-ray tubes. In this case, despite the finite size of the focal spot of the target of the tube, a full lens, as in the case of a quasi-point source, forms an X-ray beam converging to a point, and half-LINE - a quasi-parallel X-ray beam. In the latter case, the beam being formed in the cross section repeats the projection shape of the focal spot of the target of the x-ray tube onto a plane perpendicular to the longitudinal axis of the half lens.

The foregoing is illustrated in FIG. 3 for the full lens 1 and FIG. 4, FIG. 5 for half lens 3. In these and subsequent drawings, the full lens 1 and half lens 3 are shown schematically with the replacement of the curved generatrices of barrel-shaped surfaces with broken lines; while the left and right parts of the full lens 1 are highlighted by different hatching.

In FIG. 3 shows two positions 12.1 and 12.2 of the focal spot of an x-ray tube target. As shown in FIG. In 3 cases, the focal spot has the shape of a circle. At position 12.1, the focal spot is offset relative to the focus 10 of the full lens 1 along the longitudinal axis 11 in the direction of removal from the input end 5. At position 12.2, the offset is opposite in the direction of approach to the input end 5. In both cases, the focal spot is inscribed in the solid angle 13 formed by the continuation of the channels of the full lens 1 in the direction of the source of diverging x-ray radiation. Therefore, in both shown in FIG. In 3 cases, in the full lens 1, all radiation transport channels are used. The radiation emerging from the output end face 6 of the full lens, at both positions (12.1 and 12.2) of the focal spot of the target of the x-ray tube, is focused at point 7 - as if a point radiation source located at the focus 10 of the full lens were used. In the perpendicular longitudinal axis 11 of the plane 14, located to the right of the output focus 7, an x-ray image 15 of the focal spot of the target tube can be obtained, having a size depending on the distance of the plane 14 from the focus 7.

In FIG. 4 shows the conversion of the divergent radiation of an x-ray tube carried out by lulinza 3, for the same as in FIG. 3

positions 12.1 and 12.2 of the focal spot of the x-ray tube target. As in FIG. 3, the focal spot in both positions (12.1 and 12.2) is inscribed in the solid angle 13 formed by the extensions of the channels of the half lens 3 towards the source of the diverging x-ray radiation. Therefore, in the half lens 3 in both shown in FIG. In 4 cases, all radiation transport channels are used. The flux 8 of radiation emerging from the half lens 3 is quasi-parallel - the same as it would be in the case of a point x-ray source located at focus 10.

The ability of the lens to capture radiation emanating from the entire area of the focal spot of the target of the x-ray tube, when using a full lens, provides the highest intensity in the output focus, and when using a half-lens, the highest energy density in the generated quasiparallel beam.

As noted above, when using a half-lens, it is possible to obtain a beam that in cross section repeats the projection of the focal spot of the scaffold of the x-ray tube onto a plane perpendicular to the longitudinal axis of the half-lens. FIG. 5 illustrates the implementation of this feature when the focal spot has the shape of an elongated rectangle (the so-called linear focus). The same shape of the output beam 13 can be obtained at two positions 17.1, 17.2 of the focal spot of the target, symmetrical with respect to the focus 10 of the half lens 3.

The possibility of obtaining a quasiparallel beam of a rectangular shape (including, in the form of a dash, a strongly elongated rectangle) without the energy losses inherent in the collimation method of forming such a beam, makes the use of the proposed device in diffractometric studies very promising.

meters of the output parallel beam (positions 19-21 in Fig. 6), including in the process or off from the process of forming the output beam part of the channels of the half lens 3. When the focal spot 18 of the target of the tube approaches the focus 10 of the half lens 3, the moment comes when the radiation from some peripheral focal spot elements cannot be captured by a half lens. Moreover, the shape of the output beam no longer corresponds to the shape of the focal spot. Starting from the moment when all the channels of the half-lens are able to capture radiation, the shape of the beam ceases to change and corresponds to the cross-sectional shape of the half-lens (position 22 in Fig. 6).

In order to excite a region of a rectangular shape on the test sample by a converging or diverging x-ray beam, a full lens 1 can be used in combination with an x-ray tube having a linear focus. If the linear focus occupies the positions 23.1 or 23.2 (Fig. 7), then the full lens 1 in the planes perpendicular to the longitudinal axis 11 forms x-ray images of the linear focus. In FIG. 7 shows such an image 24 formed by diverging beams in a plane 14 located behind the output focus 7. If this plane were located between the output end 6 of the full lens and its output focus 7, then this image would be formed by converging beams. Rectangles 25, 26 in FIG. 7 shows the usable portion of the channels of a full lens 1 with a focal spot of an x-ray tube target having a rectangular shape.

The equivalence of the location of the focal spot of the target of the x-ray tube on opposite sides of the input focus of the lens, illustrated by the above examples, allows the device to be implemented in the presence of constructive restrictions on the approach of the lens to the source (such restrictions occur, in particular, in the case of using a short-focus lens and an x-ray tube with side output radiation).

To do this, it is enough to use the location corresponding to options 12.1 (Fig. 3, Fig. 4), 17.1 (Fig. 5), 23.1 (Fig. 7), i.e. to shift the focal spot of the target of the tube from the focus of the lens in the direction of removal from its input end, and use a weakly focused x-ray tube.

For the most full use of the radiation energy of the tube with a linear focus, you can also resort to its inclined location relative to the longitudinal axis 11 of the lens (Fig. 8). The radiation of all elements of the linear focus 27 is captured by the full lens 1 and is concentrated in its output focus 7.

FIG. 9 illustrates a similar situation with respect to the half lens 3. In this drawing, two variants of the location of the focal spot of the scaffold of the x-ray tube are shown — perpendicular (28) and inclined (29) to the longitudinal axis 11 of the half lens 3.

At the same specific brightnesses of the focal spots 28 and 29, the intensity of the output quasi-parallel beam in the case of an inclined position of the spot 29 will be higher.

If the shape of each of the focal spots 28, 29 is the corresponding conical section of the surface bounding the solid angle 13, then all channels of the half lens 3 will be used to transport the radiation. Therefore, the beam 8 emerging from it will not differ in shape from that which occurs with the point source located at input focus 10.

The proposed device, represented by the described options for its implementation and use, allows simple means to provide an acceptable radiation intensity when conducting studies using low-power x-ray tubes.

Sources of information

1. Synchrotron radiation. Ed. K. Kuntsa. Moscow, Mir Publishing House, 1981.

2. V.A. Arkadiev, A. I. Kolomiytsev, M. A. Kumakhov and others. Broadband X-ray ontics with a large angular aperture. Uspekhi Fizicheskikh Nauk, 1989, Volume 157, Issue 3, p. 529-537.

3. U.S. Patent No. 5,175,755 (publ. 29.12.92).

4. U.S. Patent 5,570,408 (publ. 10/29/96).

5. International application PCT / RU 00/00324 (international publication WO 02/12871 of 02/14/2002).

6.V.M. Andreevsky, M.V. Gubarev, P.I. Zhidkin, M.A. Kumakhov, A.V. Noskin, I.Yu. Ponomarev, Kh.Z.Ustok. X-ray waveguide system with a variable cross-section of the sections. The IV-th Ail-Union Conference on Interaction of Radiation with Solids. Book of Abstracts (May 15-19, 1990, Elbrus settlement, Kabardino-Balkarian ASSR, USSR, pp. 177-178).

7. International application PCT / RU 00/00206 (international publication WO 01/29845 of 04/26/2001).

8. US patent No. 6,271,534 (publ. 07.08.2001).

Claims (6)

1. A device for producing x-ray radiation of increased brightness, comprising an x-ray tube forming a diverging x-ray beam, and an x-ray lens mounted and configured to capture a portion of the diverging x-ray beam and converting it into a quasi-parallel or focused one, characterized in that the x-ray tube made with a focal spot of the target, the size of which exceeds the size of the focal region of the x-ray lens in the plane, perpendicular the longitudinal axis of the x-ray lens, while the x-ray tube is mounted so that the focal spot of its target is offset relative to the input focus of the x-ray lens along the longitudinal axis of the x-ray lens.  2. The device according to claim 1, characterized in that the focal spot of the target of the x-ray tube has an offset relative to the input focus of the x-ray lens toward approaching the input end of the x-ray lens.  3. The device according to claim 1, characterized in that the focal spot of the target of the x-ray tube has an offset relative to the focus of the x-ray lens away from the input end of the x-ray lens.  4. The device according to any one of claims 1 to 3, characterized in that the focal spot of the target of the x-ray tube is completely located within the solid angle formed by the extensions of the channels of the x-ray lens towards the output window of the x-ray tube, and reaches its boundaries with its peripheral points.  5. The device according to claim 5, characterized in that the x-ray tube has a linear focus. 6. The device according to claim 5, characterized in that the linear focus of the x-ray tube is oriented obliquely with respect to the longitudinal axis of the x-ray lens.