JP5153388B2 - X-ray generator, X-ray analyzer, X-ray transmission image measuring device, and X-ray interferometer - Google Patents

Description

  The present invention relates to an X-ray generator that emits X-rays of a minute spot from a stable position without being affected by position fluctuations caused by electron beam drift, an X-ray analyzer including the X-ray generator, and an X-ray analyzer The present invention relates to a transmission image measuring apparatus and an X-ray interferometer.

  Japanese Patent Publication No. 34-10727 (Patent Document 1), Japanese Patent Application Laid-Open No. 7-169422 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2001-35428 (Patent Document 3) are known as conventional techniques related to X-ray tubes. ing.

  In Patent Document 1, an anode component base material of an X-ray tube is filled with a tungsten anode material having a required focal area to form an anode, and X-rays from the anode base material are well absorbed in the traveling direction of the generated X-rays. A fine anode X-ray tube is described in which a filter of one or more substances made of a material is screened.

  Further, in Patent Document 2, in an X-ray tube in which a cathode filament and a heavy metal anode target piece are arranged to face each other in a vacuum envelope, and the anode target piece is supported by an anode substrate, the anode substrate is synthesized. It is described that it consists of diamond.

  Patent Document 3 discloses a tube main body that can be evacuated inside, an electron source that is provided in the tube main body and generates an electron beam in the tube main body, and is provided in the tube main body from the electron source. An X-ray generator comprising a metal target that generates X-rays upon irradiation with an electron beam, wherein the metal target is composed of a metal thin film patterned in a minute size, and the electron beam is formed on the metal target. It is provided that a part of the irradiated surface is irradiated and the metal target is embedded in the base material.

Japanese Patent Publication No. 34-10727 JP-A-7-169422 JP 2001-35428 A

  However, none of the above-mentioned Patent Documents 1 to 3 considers the stable emission of high-power X-rays in a certain direction without being affected by fluctuations in the electron beam irradiation target position.

  An object of the present invention is to solve the above-mentioned problems by using a single X-ray having a small diameter of about 10 to 50 μm without affecting the position of the electron beam irradiation target by about several μm due to electromagnetic factors. To provide an X-ray generator capable of stably taking out a plurality of beams in a fixed direction, an X-ray analyzer equipped with the X-ray generator, an X-ray transmission image measuring device, and an X-ray interferometer It is in.

  In order to achieve the above object, the present invention provides a tube main body configured to be evacuated inside, an electron source for generating an electron beam in the tube main body, and provided in the tube main body, from the electron source. In an X-ray generator comprising a target member for generating X-rays by irradiation with an electron beam, the target member is made of a plurality of repeated striped metal thin films (metal targets) having a small width. The characteristic X-rays are emitted from the specific stripe-shaped metal thin film (metal target) at a low angle through the X-ray window by irradiating the specific stripe-shaped metal thin film (metal target) with the electron beam. It is characterized by being configured to emit light.

  In the X-ray generator according to the present invention, the fine width of the stripe-shaped metal thin film (metal target) embedded in the base material is narrower than the diameter of the electron beam irradiated onto the target member. It is characterized by that.

  Further, the present invention is characterized in that the X-ray generator further comprises an electron lens that focuses and irradiates an electron beam emitted from the electron source onto the target member.

  In the target member of the X-ray generator, when the base material is formed of a copper material, the striped metal thin film is made of molybdenum, gold, silver, tungsten, nickel, or chromium. It was formed using.

  Further, in the target member of the X-ray generator, when the base material is formed of a copper material and a tungsten film on the surface thereof, the striped metal thin film is formed of molybdenum, gold, silver. , Copper, nickel, or chromium.

  Moreover, the present invention is characterized in that the diameter of the electron beam irradiated on the target member of the X-ray generator is within a range of 40 to 500 μm.

  In the X-ray generator according to the present invention, the target member has a synthetic diamond layer on a base of the striped metal thin film.

  In addition, the present invention is an X-ray analysis apparatus comprising the X-ray generation apparatus.

  In addition, the present invention is an X-ray transmission image measuring apparatus comprising the X-ray generator.

  The present invention also provides an X-ray interferometer including the X-ray generator.

  According to the present invention, in an X-ray generator, even if an electron beam irradiation position of about several μm drifts on the target member due to electromagnetic factors, characteristic X-rays with a minute diameter of about 10 to 50 μm are directed in a certain direction. It was possible to emit light stably.

  X-ray generator (X-ray tube) provided with a striped X-ray metal target (metal thin film) according to the present invention, an X-ray analyzer provided with the X-ray generator, an X-ray transmission image measuring device, and an X-ray An embodiment of an interferometer will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view showing a first embodiment of an X-ray generator (X-ray tube) provided with a striped X-ray metal target (metal thin film) according to the present invention. FIG. 2 is a cross-sectional view showing a first embodiment of an X-ray generator (X-ray tube) provided with a striped X-ray metal target (metal thin film) according to the present invention. That is, in the first embodiment of the X-ray generator (X-ray tube) according to the present invention, the target for forming the electron source 2 and the anode 3 on the stainless steel X-ray tube main body 1 configured to be evacuated inside. Members 3a and 3b are provided. The electron source 2 emits thermoelectrons when heated by the filament power source 41 and the filament 21 constituting the cathode and the electron beam 23 are about 30 to 60 μm (when the characteristic X-ray diameter is about 10 to 30 μm). And a converging electron lens 22. The electron lens 22 exhibits the same effect regardless of whether it is based on an electrostatic field or a magnetic field. In this embodiment, an electrostatic lens is used, and it is possible to obtain a convergence diameter of 30 to 60 μm on the metal target of the electron beam without applying the bias voltage 42 in particular. Between the filament 21 and the anode 3, a high voltage power source 4 for irradiating an electron beam 23 focused on a metal target (metal thin film) 3a is provided. The generated X-rays 35 that are emitted in the direction of the X-ray extraction window 34 are extracted from the X-ray generator and used.

  The target member 31 is narrower than the target X-ray generation beam diameter at a thickness of about 10 to 20 μm on a base material 3a made of copper (Cu) or the like having high thermal conductivity (0.94 cal / cm · sec · deg). Striped metal target (metal thin film) having a width (for example, molybdenum (Mo), gold (Au), silver (Ag), tungsten (W), nickel (Ni), chromium (Cr), etc.)) 3b from the target surface It is formed by being repeatedly embedded at a predetermined pitch (interval) in a direction substantially perpendicular to the exit extraction direction of the X-ray extraction window 34 at an angle (β) of about 3 to 15 degrees. The predetermined pitch (interval) is about 30 to 60 μm. For this, a numerical value larger than the convergence diameter of the electron beam is used. Further, the target member 31 has a target X-ray generation beam diameter of about 10 to 20 μm when the base material 3a is formed by forming a copper material having a high thermal conductivity and a tungsten film on the surface thereof. Target a striped metal target (metal thin film) 3b (for example, molybdenum (Mo), gold (Au), silver (Ag), copper (Cu), nickel (Ni), chromium (Cr), etc.)) 3b having a narrower width It is formed by being repeatedly embedded at a predetermined pitch (interval) in a direction substantially perpendicular to the emission extraction direction of the X-ray extraction window 34 at an angle (β) of about 3 to 15 degrees from the surface. Further, as shown in FIG. 2, a flow path through which the cooling water 5 flows is provided on the back surface of the target member 31 so that heat generated in the target member 31 can be removed. In addition to the method of directly cooling the back surface of the target member 31, heat can be removed by cooling the surface of the X-ray tube 1 with the heat conductive ceramics 36 so as to remove the heat from the target member 31 as shown in FIG. It is.

  In the present invention, since the base member 3a and the striped metal thin film 3b are used for the target member 31, characteristic X-rays from two or more kinds of metals are emitted from the target by irradiation with an electron beam. The characteristic X-ray is determined for each metal. For example, the characteristic X-ray (Kα) of copper (Cu) used for the base material 3a is 8.04 keV, and the molybdenum (Mo) characteristic when molybdenum is used for the striped metal thin film 3b. X-rays (Kα) 17.4 keV are emitted at the same time. Of these, in order to use only 17.4 keV characteristic X-rays, the sample is irradiated with X-rays using an X-ray discrimination monochromator shown in FIG. 4 or an X-ray selection device 51 such as a reflecting mirror formed with a multilayer film. Sometimes. As a method not using the X-ray selection device 51, an X-ray analysis apparatus, an X-ray transmission image measurement apparatus using the X-ray generation apparatus 11 of the present invention shown in FIG. By applying a device having X-ray discrimination capability, a desired analysis result can be obtained by performing data analysis using only data derived from characteristic X-rays of 17.4 keV in the data processing device 55. .

  The X-ray excitation electron beam 23 is converged and irradiated by an electrostatic field or an electromagnetic field. The electron beam is changed by a change in geomagnetism or an X-ray analyzer, an X-ray transmission image measuring device, or a drive motor of the X-ray analyzer. The convergence position slightly deviates from the target position due to the magnetic field. For this reason, by using a metal material having a magnetic shielding effect for the electron lens 22, it is possible to suppress the deviation or temporal variation of the electron beam convergence position. However, it is difficult to completely block the influence of the surrounding magnetic field, and a slight misalignment occurs.

  Since the X-ray generator (X-ray tube) according to the present invention is configured to irradiate the stripe-shaped metal thin film target 3b with a focused electron beam, even if the magnetic field affects the electron beam irradiation position, a desired characteristic X-ray is obtained. Since the portion that generates the light has a stripe shape, the position of the X-ray generation does not change in the direction component orthogonal to the stripe-shaped metal thin film target 3b. On the other hand, when the position varies in a direction parallel to the stripe-shaped metal thin film 3b, a variation 25 of the electron beam irradiation position 24 occurs as shown in FIG. However, in the X-ray generation apparatus (X-ray tube) of the present invention, since the X-ray extraction angle (β) with respect to the surface of the target member 31 is selected to be 6 degrees, as shown in FIG. 6 apparent in the X-ray extraction direction. The position variation is suppressed to about 1/10 of the variation on the surface of the target member 31. Therefore, even if an electron beam with a diameter of 30 μm moves to a position of 10 μm, the position fluctuation of the X-ray generation part is suppressed to about 1 μm, and can be suppressed to a position fluctuation within 5% of the diameter of the X-ray generation part. It is. Here, if the shape of the electron beam 23 that irradiates the stripe-shaped metal thin film target 3b is selected to be a quotient size divided by the stripe width and sin β in the direction parallel to the stripe, the apparent size of the X-ray beam is obtained. A similar shape such as a circle or a square can be used, which is preferable in use. The X-ray extraction angle (β) can be selected within a range of 3 to 15 degrees.

  In the present invention, by forming a plurality of stripe-shaped metal thin film targets 3b, the initial adjustment of the electron beam irradiation position can be performed by moving the electron source 2 horizontally by a distance corresponding to the distance between the stripes at the maximum. A target position that can be taken out can be obtained. For this reason, the configuration of the present invention has achieved high productivity as a microfocus X-ray generator.

[Second Embodiment]
The second embodiment of the X-ray generator (X-ray tube) provided with the striped X-ray metal target (metal thin film) according to the present invention is different from the first embodiment in that FIG. Will be described.

  The difference between the second embodiment shown in FIG. 6 and the first embodiment is that a synthetic diamond layer having a thermal conductivity of 2 to 5 times the thermal conductivity of copper on the base of the metal thin film target member 3b. 33 is formed. The feature of this structure is that the current caused by the electron beam irradiation is returned to the X-ray generation high-voltage power supply 4 by electrical conduction of the metal thin film target 3 b, and the generated heat is transmitted by the metal thin film target member 3 b and the diamond layer 33. Here, the thickness of the metal thin film target member 3b is about the penetration depth of the electron beam, and is about 10 to 50 μm. Since the heat conduction of the metal thin film having a thickness of 50 μm or less is not large, the heat conduction is mainly performed by the diamond layer 33 formed thicker than the metal thin film target material 3b. Since the diamond layer 33 has a high thermal conductivity, the cooling efficiency of the electron beam irradiation site, which is the X-ray generation site, is greater than the case where the entire target is formed of a single metal. This effect is shown in FIG.

  Assuming that the thermal conductivity of the synthetic diamond layer 33 is twice that of copper and the thickness of the synthetic diamond layer is equal to or greater than the diameter of the electron beam irradiation site serving as the X-ray generation site, as shown by the chain line in FIG. The cross-sectional area of the portion 37 showing the heat flow is about 4.5 times or more, and it is possible to irradiate a larger electron beam power than when the synthetic diamond layer is not used under the metal thin film target member 3b. Actually, heat conduction loss or the like occurs at the interface from the metal thin film target member 3b to the diamond layer 33, so that the heat flow rate is about double.

  Even if the metal thin film target 3b produced on the synthetic diamond layer 33 has a stripe-like structure, the effects on the heat conduction and the metal thin film target cooling are the same. By using the second embodiment according to the present invention, the metal thin film target 3b is conventionally used. It is possible to apply a higher electron beam power than the example. Therefore, it becomes possible to apply an electron beam power of 50 W or more to an electron beam irradiation diameter of 30 μm by an X-ray generator (X-ray tube) having a metal thin film target and a diamond high thermal conductive layer according to the present invention. It is possible to provide a stable X-ray generation apparatus in which the position variation of the X-ray generation site is 3 μm or less. Furthermore, by using the X-ray generator (X-ray tube) according to the present invention to form an X-ray analyzer, an X-ray transmission image measuring device, or an X-ray interferometer, the analysis accuracy is high and stable compared to the prior art. It is possible to provide an X-ray analysis apparatus, a high-resolution X-ray transmission image measurement apparatus, or an X-ray interferometer.

The perspective view which shows schematic structure of 1st Embodiment of the X-ray generator (X-ray tube) provided with the stripe-shaped metal thin film target which concerns on this invention. The perspective view which shows the structure of the metal thin film target and cooling method of 1st Embodiment of the X-ray generator (X-ray tube) provided with the stripe-shaped metal thin film target which concerns on this invention. The perspective view which shows the structure of the method of cooling a metal thin film target from the X-ray tube outer side of 1st Embodiment of X-ray generator (X-ray tube) provided with the stripe-shaped metal thin film target which concerns on this invention. FIG. 1 is a first schematic diagram illustrating the configuration of an X-ray analyzer, an X-ray transmission image measuring device, and an X-ray interferometer using an X-ray generator (X-ray tube) including a stripe-shaped metal thin film target according to the present invention. The perspective view which shows the structure of the metal thin film target of this embodiment, and the cooling method. The top view which shows the movement of a striped metal thin film target and electron beam concerning the present invention. The perspective view which shows the structure of the metal thin film target and cooling method of 2nd Embodiment of the X-ray generator (X-ray tube) provided with the stripe-shaped metal thin film target which concerns on this invention. Explanatory drawing of the highly efficient cooling method of the metal thin film target of 2nd Embodiment of the X-ray generator (X-ray tube) provided with the striped metal thin film target which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... X-ray tube main body, 2 ... Electron source, 3 ... Anode, 4 ... High voltage power supply, 11 ... X-ray generator, 21 ... Filament, 22 ... Electron lens, 23 ... Electron beam, 24 ... Electron beam irradiation part, 25 ... Position variation of electron beam, 31 ... Target member, 3a ... Base material, 3b ... Metal target, 33 ... Diamond layer, 35 ... X-ray, 36 ... Thermally conductive ceramics, 37 ... High heat flow rate part, 41 ... Filament power source, 42 ... Bias power supply, 51... X-ray selection device, 52... X-ray analyzer or X-ray transmission image measuring device or X-ray interferometer, 53.

Claims (4)

A tube main body configured to be evacuated inside, an electron source that generates an electron beam in the tube main body, an X-ray that is provided in the tube main body and irradiated with an electron beam emitted from the electron source In an X-ray generator provided with a target member for generating
An electron lens for focusing and irradiating an electron beam emitted from the electron source on the target member within a range of 30 to 60 μm in diameter is used, and a metal material having a magnetic shielding effect is used for the electron lens. ,
Further, the target member, the substrate of the thermal conductivity of 2 to 5 times the synthetic diamond layer of copper, than the diameter of the electron beam irradiated onto the target member repeated a formed on the substrate It is composed of a plurality of narrow micro-width striped metal thin films, and the synthetic diamond layer substrate is formed thicker than the striped metal thin films,
The electron beam emitted from the electron source is focused on the stripe-shaped metal thin film by the electron lens and irradiated to emit characteristic X-rays generated from the stripe-shaped metal thin film to the outside through an X-ray window at a low angle. And an X-ray generator that cools the striped metal thin film by transferring heat generated from the striped metal thin film to the base material of the synthetic diamond layer.   An X-ray analyzer comprising the X-ray generator according to claim 1.   An X-ray transmission image measurement apparatus comprising the X-ray generation apparatus according to claim 1.   An X-ray interferometer comprising the X-ray generator according to claim 1.

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