JP6617368B2 - How to make an electron source - Google Patents

Description

  The present invention relates to an electron source and a manufacturing method thereof. The present invention also relates to an X-ray generation device, a cross-sectional image acquisition device, and an X-ray communication device using an electron source.

  Conventionally, as an electron source, there is one using a carbon nanostructure and a metal mesh. A metal mesh is disposed at a position away from the surface of the carbon nanostructure. In this state, by applying a positive voltage (for example, +10 kV) to the metal mesh with respect to the surface of the grounded carbon nanostructure, electrons are emitted from the carbon nanostructure. The emitted electrons are guided to a desired position through the metal mesh. Such an electron source is described in Patent Document 1 below, for example.

  Other prior art documents include the following patent documents 2 to 4. Patent Documents 2 and 3 describe “carbon films” that can be used in embodiments of the present invention. Patent Document 4 describes a gas electron amplifier (GEM) that amplifies photoelectrons that jump out of gas electrons due to the photoelectric effect of radiation and gas upon incidence of radiation.

Japanese Patent No. 4790324 JP 2007-234485 A JP2011-8998A JP 2008-150253 A

In the electron source described above, it is necessary to apply a strong electric field to the carbon nanostructure in order to emit electrons from the carbon nanostructure. For example, it is necessary to apply a strong electric field of the order of 10 ⁶ V / m to the surface of the carbon nanostructure. Therefore, it is necessary to generate a large potential difference between the carbon nanostructure and the metal mesh. For example, since the distance between the surface of the carbon nanostructure and the metal mesh is several centimeters, it is necessary to apply a voltage of 10 kV to the metal mesh.

  Therefore, an object of the present invention is to provide means capable of emitting electrons with a lower applied voltage.

In order to achieve the above object, according to the present invention,
A carbon support having carbon nanostructures formed on the surface;
A foil-like body for applying an electric field to the carbon nanostructure,
A large number of through holes are formed in the foil-like body,
The foil has a first surface attached to the surface of the carbon support and a second surface located on the opposite side of the first surface with respect to the thickness direction of the foil.
The second surface and the carbon nanostructure are insulated from each other,
By applying a voltage between the carbon nanostructure and the second surface such that the carbon nanostructure and the second surface have a negative potential and a positive potential, respectively, An electron source that emits electrons through the plurality of through holes is provided.

  The above-described electron source can be configured as follows, for example.

The carbon nanostructure has a large number of needle-like parts,
Each needle-like portion has a tip opposite to the surface of the carbon support, and becomes thinner as it approaches the tip.

  The surface of the carbon support and the second surface of the foil-like body are planes parallel to each other.

The carbon support having the surface on which the carbon nanostructures are formed and the foil-like body are separately manufactured,
A fixing tool is provided for fixing the carbon support and the foil to each other in a state where the first surface of the foil is in contact with the surface of the carbon support.

The electron source is provided together with an ion engine in a spacecraft that moves in outer space,
The ion engine gives a thrust to the spacecraft by releasing positive ions to the outside of the spacecraft,
The electron source emits electrons to the outside of the spacecraft so that the spacecraft is not charged due to the release of the cations to the outside of the spacecraft.

According to the present invention, there is also provided a method for producing the above-described electron source,
While preparing the carbon support having the surface on which the carbon nanostructure is formed, preparing the foil-like body,
Next, an electron source that fixes the carbon support and the foil-like body to each other with a fixture in a state of being in contact with the first surface of the foil-like body on the surface of the carbon support. Is provided.

According to the invention, an electron source as described above;
An X-ray generation apparatus is provided that includes a target that generates X-rays when electrons emitted from the electron source are incident thereon.

  The above-described X-ray generator can be configured as follows, for example.

The target is a flat plate-type transmission target arranged in parallel with the foil-like body,
A collimator disposed on the opposite side of the electron source with respect to the target;
The collimator selectively allows X-rays traveling in a direction perpendicular to the target out of X-rays from the target.

According to the present invention, a cross-sectional image acquisition device for an inspection object including the above-described X-ray generator,
A plurality of the X-ray generators that irradiate the inspection object with X-rays from different directions as viewed from the inspection object;
A plurality of X-ray detectors respectively corresponding to the plurality of X-ray generators;
A control device for controlling the timing of generating X-rays from the plurality of X-ray generation devices,
Each X-ray generation device and the X-ray detector corresponding to the X-ray generation device are arranged to face each other, and between the X-ray generation device and the X-ray detector facing each other, The inspection object is disposed;
The control device generates X-rays from the plurality of X-ray generation devices at different timings,
Each of the X-ray detectors generates X-ray detection data by detecting X-rays emitted from the corresponding X-ray generator and passing through the inspection object,
There is provided a cross-sectional image acquisition device for an inspection object, comprising a data processing device for generating a cross-sectional image of the inspection object based on the X-ray detection data generated by a plurality of the X-ray detectors.

According to the present invention, the aforementioned X-ray generator;
A control device for generating X-rays from the X-ray generation device at time intervals;
An X-ray detector that receives the X-rays generated from the X-ray generator at the time interval;
A signal generation device that generates signal data based on reception of X-rays by the X-ray detector,
The signal generating device generates first signal data corresponding to the time interval at which the X-ray detector receives X-rays;
(A) The control device changes the time interval,
(B) Thereby, when the time interval at which the X-ray detector receives X-rays changes,
(C) An X-ray communication apparatus is provided in which the X-ray detector generates second signal data corresponding to the changed time interval.

In the electron source of the present invention, the first surface of the foil-like body is attached to the carbon nanostructure. In this case, since the thickness of the foil-like body is small, the distance between the second surface having a positive potential and the carbon nanostructure having a negative potential is small. Therefore, even if a low positive voltage is applied to the second surface of the foil-like body, a strong electric field is generated in each through-hole of the foil-like body. When this strong electric field is applied to the carbon nanostructure, electrons are emitted from the carbon nanostructure. Therefore, a low positive voltage can be applied to the second surface of the foil-like body to emit electrons.

1 shows a configuration of an electron source according to an embodiment of the present invention. It is an enlarged view which shows the carbon nanostructure in the through-hole of a foil-like body. It is a flowchart which shows the manufacturing method of an electron source. It is attachment explanatory drawing of the foil-like body to a carbon support body. The case where the electron source of this embodiment is applied to an ion engine is shown. 1 shows an X-ray generator according to an embodiment of the present invention. The X-ray generation sustained characteristic of the X-ray generator is shown. 1 shows a cross-sectional image acquisition device for an inspection object including a plurality of X-ray generation devices. (A) shows the X-ray communication apparatus provided with the X-ray generator, and (B) shows the time of X-ray generation.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

[Electron source]
FIG. 1 shows a configuration of an electron source 10 according to an embodiment of the present invention. 1A is a cross-sectional view, and FIG. 1B is a view taken along the line BB in FIG.

  The electron source 10 includes a carbon support 3, a carbon nanostructure 5, and a foil-like body 7.

  Carbon nanostructures 5 are formed on the surface 3 a of the carbon support 3. As will be described later, since the foil-like body 7 is attached to the surface 3a, the carbon nanostructure 5 is crushed by the foil-like body 7 in a region other than the through-hole 7a of the foil-like body 7. Good.

  The carbon support 3 is made of a conductive material. Therefore, the carbon support 3 and the carbon nanostructure 5 have the same potential. In the example of FIG. 1A, the carbon support 3 is grounded.

  The carbon nanostructure 5 emits electrons when an electric field having a magnitude greater than or equal to a predetermined value is applied. The carbon nanostructure 5 is a film formed on the surface 3 a of the carbon support 3. This film is made of carbon. The thickness of the film is on the order of 1 μm to 10 μm, and has a value in the range of 1 μm to 50 μm, for example.

  A large number of through holes 7 a are formed in the foil body 7 in the thickness direction. The interval (pitch) between the multiple through holes 7a is, for example, on the order of 10 μm to 100 μm, and in one example, is a value within a range of 50 μm to 300 μm, and in another example, is a value within a range of 100 μm to 200 μm. is there. The diameter of the cross-section of each through-hole 7a (the horizontal dimension in FIG. 1A) is, for example, on the order of 10 μm to 100 μm, and in one example is a value within the range of 20 μm to 200 μm. It is a value within the range of 50 μm to 100 μm. The thickness of the foil-like body 7 is, for example, on the order of 10 μm to 100 μm, and is a value within a range of 10 μm to 500 μm in one example, a value within a range of 10 μm to 300 μm in another example, and in another example, It is a value within the range of 25 μm to 100 μm. The foil-like body 7 has a first surface 7 b attached to the surface 3 a of the carbon nanostructure 5 and a second surface 7 c located on the opposite side of the first surface 7 b with respect to the thickness direction of the foil-like body 7. The second surface 7c and the surface 3a of the carbon support 3 (that is, the carbon nanostructure 5) are insulated from each other.

  In the example of FIG. 1A, the foil-like body 7 includes an insulating layer 9 and a conductive layer 11. The insulating layer 9 is made of an insulator. This insulator is, for example, a polymer such as polyimide or liquid crystal polymer, but is not limited thereto. The conductive layer 11 is formed on the insulating layer 9. The conductive layer 11 is made of a conductive material. This conductive material may be, for example, copper, aluminum, gold, or boron, but is not limited thereto.

  Such a foil-like body 7 may be, for example, a gas electron amplification foil described in Patent Document 4 in which one metal layer is omitted as follows. The gas electron amplification foil of Patent Document 4 has an insulating layer and metal layers formed on both sides of the insulating layer. A configuration in which one metal layer is omitted in the gas electron amplification foil may be the foil-like body 7 in FIG. In this case, in this foil, the insulating layer functions as the insulating layer 9 in FIG. 1A, and the other metal layer functions as the conductive layer 11 in FIG.

  The surface on the carbon support 3 side in the insulating layer 9 is the first surface 7b described above. The surface opposite to the carbon support 3 in the conductive layer 11 is the second surface 7c described above.

  In the foil-like body 7, another conductive layer may be formed on the surface of the insulating layer 9 opposite to the conductive layer 11. In this case, of the two surfaces in the other conductive layer, the surface opposite to the insulating layer 9 is the first surface 7 b, and the first surface 7 b is attached to the surface 3 a of the carbon support 3.

  Preferably, as shown in FIG. 1A, the surface 3a of the carbon support 3 and the second surface 7c of the foil 7 are planes parallel to each other. In this case, the first surface 7b is preferably a plane parallel to the second surface 7c.

  FIG. 2 is a partially enlarged view of FIG. FIG. 2 shows the carbon nanostructure 5 located in the through hole 7a of the foil 7 in FIG.

The carbon nanostructure 5 has a large number of needle-like parts 6. Each needle-like portion 6 has a tip opposite to the surface 3a of the carbon support 3 and becomes thinner as it approaches this tip.
In the example of FIG. 2, the carbon nanostructure 5 has a large number of coniferous parts 5a. Each coniferous tree-shaped part 5 a has a raised part 8 and a needle-like part 6. The raised portion 8 is a portion raised from the surface 3 a of the carbon support 3, and the needle-like portion 6 is a portion extending from the tip of the raised portion 8 to the side opposite to the surface 3 a of the carbon support 3.
Such a carbon nanostructure 5 may be, for example, a “carbon film” described in Patent Documents 2 and 3.

  The electron source 10 includes a voltage application device 13 as shown in FIG. The voltage application device 13 applies a voltage between the carbon nanostructure 5 and the second surface 7c so that the carbon nanostructure 5 has a negative potential and the second surface 7c has a positive potential. That is, the voltage application device 13 applies a positive voltage to the second surface 7c. The resulting potential difference between the carbon nanostructure 5 and the second surface 7c (that is, the second voltage described later) is preferably on the order of 100V, and in one example, a value within the range of 100V to 500V. In another example, the value is in the range of 100V to 300V. In the example of FIG. 1A, since the carbon support 3 is grounded, the carbon nanostructure 5 is also grounded.

  As described above, the voltage application device 13 applies a positive voltage to the second surface 7 c of the foil-like body 7. In other words, the voltage application device 13 is configured such that the voltage between the carbon nanostructure 5 and the second surface 7c is such that the carbon nanostructure 5 and the second surface 7c of the foil 7 have a negative potential and a positive potential, respectively. Apply. Thereby, electrons are emitted from the carbon nanostructures 5 in the respective through holes 7a. The emitted electrons move, for example, toward the high potential portion 14 having a higher potential than the second surface 7c. The high potential unit 14 is a target that generates X-rays, for example.

  Preferably, the electron source 10 further includes a voltage switching unit 19 and a control unit 21.

  In one example, the voltage switching unit 19 includes a first state (off state) in which the voltage application device 13 and the second surface 7c are electrically disconnected, and a first state in which the voltage application device 13 that is a power source and the second surface 7c are electrically connected. The switch is switched between two states (on state).

  In another example, the voltage switching unit 19 includes a first state in which the voltage applied by the voltage application device 13 to the second surface 7c of the foil 7 is a first voltage (electron emission stop voltage), and the voltage application device 13. Is switched between the second state in which the voltage applied to the second surface 7c of the foil 7 is the second voltage (electron emission voltage). The first voltage is a voltage that is low enough that electrons are not emitted from the carbon nanostructure 5. The first voltage is an intermediate value between 0V and the second voltage with the ground potential set to 0V. The first voltage may be, for example, about 50V, but is not limited thereto, and may be a voltage that is 50V or less and greater than 0V, or may be another value. The second voltage is higher than the first voltage and is high enough to emit electrons from the carbon nanostructure 5.

  The control unit 21 switches the voltage switching unit 19 between the first state and the second state. For example, the control unit 21 may be configured to switch the voltage switching unit 19 between the first state and the second state at each predetermined time point with respect to the elapsed time.

  The control unit 21 may be omitted. In this case, the voltage switching unit 19 is manually switched between the first state and the second state.

  FIG. 3 is a flowchart showing a method for manufacturing the electron source 10 described above.

  In step S1, a carbon support 3 having a surface 3a on which carbon nanostructures 5 are formed is prepared. That is, the carbon support 3 having the carbon nanostructure 5 formed on the entire surface 3a is prepared. The method for forming the carbon nanostructure 5 may be the same as the method for forming the carbon film described in Patent Documents 2 and 3, for example.

  In step S2, a foil-like body 7 is prepared. That is, a foil 7 prepared as follows is prepared. For example, the conductive layer 11 is formed on the insulating layer 9 by a technique such as lamination, sputter deposition, or plating. Thereby, a stacked body in which the conductive layer 11 is formed on the insulating layer 9 is obtained. Next, a large number of through-holes 7a are formed in the stacked body by a technique such as chemical etching, plasma etching, or laser processing. Thus, the laminated body in which many through-holes 7a were formed becomes the foil-like body 7.

  Next, in step S3, the carbon support 3 and the foil 7 prepared separately and prepared in steps S1 and S2 are attached to each other as shown in FIG. That is, in a state where the first surface 7b of the foil-like body 7 is in contact with the surface 3a of the carbon support 3 on which the carbon nanostructure 5 is formed, the carbon support 3 and the foil-like body 7 are brought into contact with each other. Fix it. This fixation may be performed by one or more fasteners 15 (eg, bolts or screws). The operation of attaching the carbon support 3 and the foil 7 to each other may be performed by, for example, a human hand.

In the example of FIG. 4, the fixture 15 is a bolt, and the carbon support 3 is formed with a mounting hole 17 into which the bolt 15 is inserted. A female screw 17 a is formed on the inner peripheral surface of the mounting hole 17. The male screw portion 15 a of the bolt 15 passes through the foil-like body 7 and is screwed into the female screw 17 a on the inner peripheral surface of the mounting hole 17. Thereby, the foil-like body 7 is sandwiched between the head 15b of the bolt 15 and the male screw portion 15a, and the carbon support 3 and the foil-like body 7 are fixed to each other. In FIG. 4, the area of the second surface of the foil-like body 7, for ^example, of the order of 1 mm 2 to 1 m ^{2, or} of the order of 1 cm 2 to 1 m ^2, for ^example, of 1 mm 2 to 1 m ² It may be a value within the range.

  Therefore, the electron source 10 has the fixture 15 that fixes the carbon support 3 and the foil 7 to each other in a state where the first surface 7b of the foil 7 is in contact with the surface 3a of the carbon support 3. Is provided.

After step S3, in step S4, wiring according to the application of the electron source 10 is performed. That is, the second surface 7c of the foil-like body 7 and the voltage applying device 13 are electrically connected by, for example, a conductive wire, and the carbon support 3 is grounded. Moreover, the voltage switching part 19 and the control part 21 are provided.
Thereby, as described above, the voltage application device 13 can apply a positive voltage to the second surface 7c to emit electrons from the carbon nanostructure 5 in the through hole 7a.

  According to the electron source 10 of the embodiment of the present invention described above, the following effects are obtained.

  In the electron source, the first surface 7 b of the foil 7 is attached to the carbon nanostructure 5. In this case, since the thickness of the foil 7 is small, the distance between the second surface 7c having a positive potential and the carbon nanostructure 5 having a negative potential is small. This distance is, for example, on the order of 10 μm to 100 μm. In one example, the distance is in the range of 10 μm to 500 μm. In another example, the value is in the range of 10 μm to 300 μm. The value is within the range. Therefore, even if a low positive voltage is applied to the second surface 7 c of the foil 7, a strong electric field is generated in each through-hole 7 a of the foil 7. By applying this strong electric field to the carbon nanostructure 5, electrons are emitted from the carbon nanostructure 5. Therefore, a low positive voltage can be applied to the second surface 7c of the foil 7 to emit electrons.

Moreover, since the carbon nanostructure 5 has the needle-like portion 6, the electric field tends to concentrate on the tip of the needle-like portion 6. Therefore, electrons are easily emitted from the tip of the needle-like portion 6.
Therefore, a low positive voltage (for example, a positive voltage (second voltage) on the order of +100 V with the ground potential set to 0 V) is applied to the second surface 7 c of the foil-like body 7 with respect to the grounded carbon nanostructure 5. Thus, electrons can be emitted from the carbon nanostructure 5.

  In order to emit electrons, the value of the voltage applied to the second surface 7c of the foil-like body 7 can be set to the order of +100 V. Therefore, the voltage application device 13 can be reduced in size and power consumption can be suppressed.

  The electron emission timing can be controlled on the order of 1 nanosecond as follows. The potential of the second surface 7c is changed between the first voltage (for example, about 50V) and the second voltage on the order of + 100V by switching the voltage switching unit 19 between the first state and the second state. Therefore, the maximum potential of the second surface 7c is low. Therefore, the time required to change the potential of the second surface 7c between the first voltage and the second voltage is on the order of 1 nanosecond (for example, a time in the range of 1 nanosecond to 10 nanoseconds). Can be. That is, it is possible to switch between a state in which electrons are emitted from the electron source 10 and a state in which electrons are not emitted from the electron source 10 in a minute time on the order of 1 nanosecond.

  Since the surface 3a of the carbon support 3 and the second surface 7c of the foil 7 are planes parallel to each other, a uniform electric field is applied to the carbon nanostructure 5 on the surface 3a of the carbon support 3 it can. Therefore, the number of electrons emitted from the carbon nanostructure 5 through each through hole 7a can be made uniform.

  Furthermore, the electron source 10 according to the present embodiment can be manufactured by attaching the carbon support 3 and the foil 7 separately manufactured to each other. Therefore, the electron source 10 can be easily manufactured.

  Further, as will be described with reference to FIG. 7 described later, the electron source 10 can stably emit electrons over a long period of time. In this respect, the electron source 10 can be used for applications that require low power consumption and stable emission of electrons over a long period of time. For example, the electron source 10 can be applied to an ion engine mounted on a spacecraft such as an artificial satellite or a space probe.

FIG. 5 shows a case where the electron source 10 is provided in the spacecraft 12 together with the ion engine 16. The spacecraft 12 moves in outer space, and is, for example, an artificial satellite or a space probe. The ion engine 16 gives thrust to the spacecraft 12 by releasing positive ions to the outside of the spacecraft 12. The electron source 10 emits electrons to the outside of the spacecraft 12 so that the spacecraft 12 is not charged due to the release of cations outside the spacecraft 12. Preferably, the electron source 10 emits electrons toward positive ions emitted from the ion engine 16 to the outside of the spacecraft 12.
In this case, as shown in FIG. 5, the above-described high potential portion 14 may be a metal mesh having a large number of openings through which electrons from the electron source 10 can pass.

[X-ray generator]
FIG. 6 shows an X-ray generator 20 according to an embodiment of the present invention. In the X-ray generator 20, the contents of the electron source 10 not described below are the same as described above.

  The X-ray generator 20 includes the electron source 10, the target 14, the collimator 23, the high voltage application device 25, the vacuum container 26, and the vacuum device 27 described above.

  The target 14 corresponds to the high potential portion 14 in FIG. In this embodiment, the target 14 is a flat plate-type transmission target arranged in parallel with the foil-like body 7. The transmission type target 14 is made of, for example, tungsten, tantalum, or molybdenum. The thickness of the transmission target 14 is, for example, on the order of 1 μm to 10 μm. When the electrons from the electron source 10 collide with the target 14, the target 14 generates X-rays. A part of this X-ray propagates to the side opposite to the electron source 10 with respect to the target 14.

  In the example of FIG. 6, the collimator 23 is disposed on the side opposite to the electron source 10 with respect to the target 14. A part of the X-rays generated by the target 14 is incident on the collimator 23. Of the X-rays generated at the target 14, X-rays that do not enter the collimator 23 may be absorbed by an X-ray shielding member (not shown).

  In the example of FIG. 6, the collimator 23 proceeds in a direction perpendicular to the flat transmission target 14 (in other words, the second surface 7 c which is a flat surface in the foil 7) among the X-rays from the target 14. Pass lines selectively. On the other hand, the collimator 23 absorbs X-rays traveling in a direction other than the direction perpendicular to the flat transmission target 14 out of the X-rays from the target 14, and blocks the passage of the X-rays.

  The high voltage application device 25 applies a high voltage to the target 14 so that the potential of the target 14 becomes higher than the potential of the second surface 7c of the foil 7 and maintains the target 14 at a high potential. Thereby, electrons from the electron source 10 collide with the target 14 and X-rays are generated at the target 14. The value of the high voltage applied to the target 14 by the high voltage application device 25 is, for example, in the order of 1 kV to 100 kV, for example, in the range of 1 kV to 100 kV, where the ground potential of the carbon nanostructure 5 is 0 V. Or a value within the range of 5 kV to 20 kV.

  An electron source 10 and a target 14 are disposed inside the vacuum vessel 26. The vacuum vessel 26 preferably has a flat plate shape. In this case, as shown in FIG. 6, the thickness direction of the vacuum vessel 26 (vertical direction in FIG. 6), the thickness direction of the foil 7, the thickness direction of the flat carbon support 3, and the flat target 14 The electron source 10 and the target 14 are arranged inside the vacuum vessel 26 so that the thickness directions of the two coincide with each other.

  The vacuum device 27 maintains the inside of the vacuum vessel 26 in a vacuum during a period in which the target 14 generates X-rays. The vacuum device 27 includes, for example, a vacuum pump or a valve (not shown).

  The following effects are acquired by the X-ray generator 20 of this embodiment mentioned above.

Since the vacuum vessel 26 can be formed into a flat plate shape, a thin and large-area X-ray generator 20 can be realized. That is, X-rays can be emitted from the widest surface of the flat transmission target 14.
Moreover, among the X-rays emitted from the widest surface of the transmission target 14 (surface perpendicular to the paper surface of FIG. 6), X-rays traveling in the direction perpendicular to the flat target 14 are selectively collimated. Pass through 23. As a result, a parallel X-ray beam having a large cross-sectional area and straightly traveling can be obtained.

  As described above, the electron source 10 can be switched between a state in which electrons are emitted and a state in which electrons are not emitted in a minute time on the order of 1 nanosecond. It is possible to switch between a state where X-rays are generated and a state where X-rays are not generated in a minute time on the order of nanoseconds.

  By setting the voltage switching unit 19 to the second state only when necessary, heat generation of the target 14 due to electron collision can be significantly suppressed.

  The X-ray generator 20 can generate X-rays stably and continuously. That is, X-rays were generated under the following experimental conditions, and the following results were obtained.

Experimental conditions In the configuration of FIG. 6, the target 14 is a reflective target, the voltage switching unit 19 is in the second state, the second surface 7c of the foil 7 is maintained at a potential of 140V, and the target 14 is 10kV. Maintained at a potential of. X-rays generated at the target 14 were counted with an X-ray detector.
-Result The result shown in FIG. 7 was obtained. In FIG. 7, the horizontal axis indicates the elapsed time, and the vertical axis indicates the number of X-ray counts by the X-ray detector.

As can be seen from FIG. 7, X-rays could be stably generated for a long time of at least about 5400 seconds (about 1.5 hours).
This also indicates that electrons are stably emitted from the electron source 10 over a long period of time.

[Application 1 of X-ray generator]
The X-ray generator 20 described above can be applied to acquisition of a cross-sectional image of the inspection object T. FIG. 8 shows a cross-sectional image acquisition device 30 for the inspection target T including a plurality of the X-ray generation devices 20 described above.

  The cross-sectional image acquisition device 30 includes a plurality of X-ray generation devices 20, a plurality of X-ray detectors 29, a control device 31, and a data processing device 33.

  The plurality of X-ray generation apparatuses 20 irradiate the same cross section (cross section by a plane) of the inspection object T from different directions as viewed from the inspection object T. In FIG. 8, for the sake of simplicity, three X-ray generators 20 are arranged. However, in order to improve the accuracy of the cross-sectional image of the inspection object T, the plurality of X-ray generators 20 include a number of X-ray generators 20. The generator 20 may be used.

  The plurality of X-ray detectors 29 correspond to the plurality of X-ray generators 20, respectively. Each X-ray generator 20 and the X-ray detector 29 corresponding to the X-ray generator 20 are arranged to face each other. The inspection object T is disposed between the X-ray generator 20 and the X-ray detector 29 facing each other.

  Each X-ray detector 29 generates X-ray detection data by detecting X-rays emitted from the corresponding X-ray generator 20 and passing through the inspection object T. That is, each X-ray detector 29 generates X-ray detection data indicating the X-ray intensity at each position on the detection line segment L that extends in a direction that intersects (preferably orthogonally) the X-ray incident direction on itself. To do. This detection line segment L is represented by a thick line segment in FIG. 8, and is in the same plane as the above-mentioned cross section irradiated with X-rays. Therefore, the foil 7 of the X-ray generator 20 corresponding to each X-ray detector 29 and the surface 3a of the carbon support 3 extend in parallel (for example, elongated) with the detection line segment L.

  The control device 31 generates X-rays from the plurality of X-ray generation devices 20 at different timings. The control device 31 includes the above-described control unit 21 shared by a plurality of X-ray generation devices 20. The control unit 21 sequentially sets the plurality of voltage switching units 19 to the second state so that the plurality of voltage switching units 19 provided in the plurality of X-ray generation devices 20 are in the second state only for a minute time that does not overlap each other. To do. Thereby, X-rays are generated from the plurality of X-ray generators 20 at different timings, and these X-rays pass through the inspection object T and are detected by the corresponding X-ray detectors 29. In addition, when each voltage switching part 19 will be in a 2nd state, the high voltage is applied to the target 14 of the X-ray generator 20 with the high voltage application apparatus 25. FIG.

  In one example, a plurality of (for example, three) X-rays shifted in the circumferential direction around the inspection object T on the planes of the respective positions shifted in the direction perpendicular to the paper surface of FIG. A generator 20 and a plurality of X-ray detectors 29 are arranged. However, the positions of the plurality of X-ray generators 20 in the circumferential direction are different between different arrangement planes. In this case, FIG. 8 shows a plurality of (three in this figure) X-ray generators 20 and a plurality of X-rays arranged in one of the plurality of arrangement planes in the direction perpendicular to the plane of FIG. A line detector 29 is shown. In such a case, while the inspection object T is intermittently or continuously sent in a direction perpendicular to the paper surface of FIG. 8 (hereinafter also referred to as a conveyance direction), a plurality of X-ray generators on each arrangement plane in this direction. 20 irradiates the same cross section of the inspection object T with X-rays. In order to perform such X-ray irradiation, the control device 31 controls the driving device that sends the inspection object T in the conveyance direction, and the cross section of the inspection object T comes to each arrangement plane in the conveyance direction. Sometimes, the X-ray generators 20 are controlled so that the X-rays are irradiated to the same cross section of the inspection target T at different timings from the plurality of X-ray generators 20 on the arrangement plane. Thereby, the X-ray detector 29 of each arrangement plane generates X-ray detection data by detecting X-rays that have passed through the cross section of the inspection target T.

  The data processing device 33 generates a cross-sectional image of the inspection target T based on the X-ray detection data generated by the plurality of X-ray detectors 29 (for example, the plurality of X-ray detectors 29 in the respective arrangement planes described above). To do. The generation of the cross-sectional image may be performed using Fourier transform.

[Application 2 of X-ray generator]
The above-described X-ray generator 20 can also be used for radio communication using X-rays (for example, in space).

  FIG. 9A shows an X-ray communication apparatus 40 including the X-ray generation apparatus 20 described above.

  The X-ray communication device 40 includes an X-ray generation device 20, a control device 35, an X-ray detector 37, and a signal generation device 39.

  The X-ray generator 20 generates X-rays as described above, and the generated X-rays propagate to the X-ray detector 37. In one example, one of the X-ray generator 20 and the X-ray detector 37 is provided in an artificial satellite that travels around the earth, and the other is provided in a space probe that is remote from the earth (eg, located near Jupiter). It is done. In another example, the X-ray generator 20 and the X-ray detector 37 are provided on different satellites. Further, the X-ray generator 20 may be used for terrestrial wireless communication. Even on the ground, the X-ray transmission device 20 can be used for communication in a place where wireless communication using light, radio waves, sound, or the like is impossible, using the X-ray transparency.

  FIG. 9B shows the time of X-ray generation. 9B, the horizontal axis indicates the elapsed time, and the vertical axis indicates the intensity of X-rays generated from the X-ray generator 20. In FIG. 9B, no X-rays are generated from the X-ray generator 20 during the time period in which the X-ray intensity is zero.

  The X-ray generator 20 intermittently emits X-rays as shown in FIG. 9B, and changes the emission time interval (for example, from ΔT1 to ΔT2 as shown in FIG. 9B). Thus, each time interval (for example, ΔT1 and ΔT2) is transmitted to the X-ray detector 37 as signal data. These time intervals can be data representing different numerical values and meanings. Each time interval ΔT1, ΔT2 is on the order of 1 nanosecond to 10 nanoseconds, and is, for example, a value within a range of 1 nanosecond to 50 nanoseconds.

  The control device 35 generates X-rays from the X-ray generation device 20 at time intervals. For example, as shown in FIG. 9B, the control device 35 generates X-rays from the X-ray generation device 20 at time points t1, t2, and t3 at time intervals ΔT1 and ΔT2.

  The control device 35 has the control unit 21 described above. The control unit 21 switches the voltage application switching unit 19 from the first state to the second state. Thereby, X-rays are generated from the X-ray generator 20, and the X-rays propagate to the X-ray detector 37.

  The case of the example in FIG. 9B will be described. The control unit 21 switches the voltage application switching unit 19 from the first state to the second state at time t1, thereby generating X-rays from the X-ray generator 20 at time t1, and immediately switching the voltage application switching unit 19 to the first state. The voltage application switching unit 19 is maintained in the first state until the time t2 when switching from the second state to the first state, so that X-rays are not generated from the X-ray generator 20 until the time t2. Next, the control unit 21 switches the voltage application switching unit 19 from the first state to the second state at time t2, thereby generating X-rays from the X-ray generator 20 at time t2, and immediately, the voltage application switching unit. By switching 19 from the second state to the first state, the voltage application switching unit 19 is maintained in the first state until time t3, so that X-rays are not generated from the X-ray generator 20 until time t3. Thereafter, the control unit 21 switches the voltage application switching unit 19 from the first state to the second state at time t3 to generate X-rays from the X-ray generator 20 at time t3, and immediately, the voltage application switching unit 19 Is switched from the second state to the first state, so that X-rays are not generated from the X-ray generator 20 until the next time point.

  Note that a high potential is continuously applied to the target 14 of the X-ray generation device 20 by the high voltage application device 25 over a period in which the X-ray communication device 40 performs X-ray communication.

  The X-ray detector 37 is generated from the X-ray generator 20 at the above-described time interval (for example, the time interval ΔT1 in FIG. 9B) (at each time point t1 and t2 in FIG. 9B). X-rays are detected. That is, the X-ray detector 37 receives these X-rays.

  The signal generation device 39 generates first signal data corresponding to a time interval (for example, time interval ΔT1) at which the X-ray detector 37 receives X-rays.

The control device 35 changes the above-described time interval (for example, from ΔT1 to ΔT2 as shown in FIG. 9B), whereby the time interval at which the X-ray detector 37 receives the X-ray is changed (for example, from ΔT1 to ΔT2). When changed, the signal generation device 39 generates second signal data corresponding to the changed time interval (for example, ΔT2).
The first signal data and the second signal data may be voltages having different values, for example, but are not limited thereto.

  In such wireless communication using X-rays, the following effects can be obtained.

  As described above, the X-ray generator 20 can be switched between a state in which X-rays are generated and a state in which X-rays are not generated in a minute time on the order of 1 nanosecond. Can be performed in a minute time on the order of 1 nanosecond to 10 nanoseconds. Therefore, the X-ray communication apparatus 40 enables smooth communication using X-rays.

  Since the X-ray communication device 40 includes the X-ray generator 20 shown in FIG. 6, it is possible to generate X-rays with excellent straightness. Therefore, X-ray communication can be realized by the small X-ray generator 20 and the X-ray detector 37, and power consumption required for communication can be suppressed.

  In addition, since the wavelength of X-rays is short, wireless communication that is not affected by Faraday rotation can be realized.

  The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention. For example, the target 14 described above may be a reflective target instead of a transmissive type. Further, the collimator 23 is not limited to the above-described configuration, and may have a configuration according to the application.

3 carbon support, 3a surface, 5 carbon nanostructure, 5a coniferous tree part, 6 needle-like part, 7 foil-like body, 7a through-hole, 7b first surface, 7c second surface, 8 raised part, 9 insulating layer DESCRIPTION OF SYMBOLS 10 Electron source, 11 Conductive layer, 12 Spacecraft, 13 Voltage application apparatus, 14 High electric potential part (target), 15 Fixing tool (bolt), 15a Male thread part, 15b Head, 16 Ion engine, 17 Mounting hole, 17a female screw, 19 voltage switching unit, 20 X-ray generation device, 21 control unit, 23 collimator, 25 high voltage application device, 26 vacuum vessel, 27 vacuum device, 29 X-ray detector, 30 cross-sectional image acquisition device, 31 control Device, 33 data processing device, 35 control device, 37 X-ray detector, 39 signal generation device, 40 X-ray communication device

Claims (3)

A carbon support having carbon nanostructures formed on the surface;
A foil-like body for applying an electric field to the carbon nanostructure,
A large number of through holes are formed in the foil-like body,
The foil has a first surface attached to the surface of the carbon support and a second surface located on the opposite side of the first surface with respect to the thickness direction of the foil.
The second surface and the carbon nanostructure are insulated from each other,
By applying a voltage between the carbon nanostructure and the second surface such that the carbon nanostructure and the second surface have a negative potential and a positive potential, respectively, A method for producing an electron source for emitting electrons through the plurality of through holes,
While preparing the carbon support having the surface on which the carbon nanostructures are formed, preparing the foil-like body produced separately from the carbon support,
Next, on the surface of the carbon support to which the foil-like body is attached, the carbon nanostructure is in a positional relationship in which it exists not only in the through-hole but also in a region other than the through-hole. A method for producing an electron source, wherein the carbon support and the foil are fixed to each other by a fixture in a state where the first surface of the foil is in contact with the surface of the support. The carbon nanostructure has a large number of needle-like parts,
2. The method of manufacturing an electron source according to claim 1, wherein each needle-like portion has a tip opposite to the surface of the carbon support, and becomes narrower as it approaches the tip. The method of manufacturing an electron source according to claim 1, wherein the surface of the carbon support and the second surface of the foil-like body are planes parallel to each other.

Images