JPH0745223A - X-ray tube - Google Patents

Abstract

PURPOSE:To provide an X-ray tube having high creating efficiency of ion gas. CONSTITUTION:An electron emitted from a cathode 21 of an electron source 20 collides with an X-ray target 40, and an X-ray is generated, and this X-ray is radiated in the direction of a transmission window 50. An infrared ray radiated from a heater 22 of the electron source 20 passes through the X-ray target 40, and advances in the direction of the transmission window 50. The X-ray generated in the X-ray target 40 and the infrared ray passing through the X-ray target 40 pass through the transmission window 50, and are emitted outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray source that emits X-rays, and more particularly to an X-ray tube used for irradiating air (or gas) with X-rays to generate an ion gas.

[0002]

2. Description of the Related Art Conventionally, a process of irradiating a charged object to be discharged with an ionized gas flow to remove the object to be discharged has been conventionally performed. The ion gas used for this treatment is generated by irradiating air (or gas) with X-rays. As an X-ray tube that emits X-rays, for example, a general tube described in Japanese Patent Publication No. 3-73094 is used. This X
As shown in FIG. 5, the X-ray tube 100 has a transmission type X-ray target 1 on the entire one end surface of a capillary plate 110.
20 is formed, and the X-rays generated by irradiating the transmission X-ray target 120 with the electron beam 130 are radiated to the outside through the capillary plate 110.

[0003]

By the way, it is known that the ionization rate, which is the generation efficiency of ion gas, is higher as the energy of X-rays emitted from the X-ray tube 100 is lower.

However, the air (or gas) that is the target of X-ray irradiation contains moisture, and this moisture causes X.
Due to the absorption of rays, X-ray tube 100 had to emit high-energy X-rays. Therefore, the ionization rate cannot be increased, which is a problem.

An object of the present invention is to solve such problems and provide an X-ray tube having a high ion gas generation efficiency.

[0006]

In order to solve the above-mentioned problems, the X-ray tube of the present invention includes an envelope, a heater arranged in the envelope, which radiates infrared rays, and an electron by heating the heater. An electron source having a cathode that emits, a transmission window provided on one surface of the envelope facing the electron emission surface of the electron source, for transmitting X-rays and infrared rays, and arranged between the electron source and the transmission window, An X-ray target having a portion that emits X-rays in the direction of the transmission window by the incidence of electrons emitted from the electron source and a portion that transmits infrared rays emitted from the heater are provided.

The X-ray target is formed with a plurality of through holes for passing infrared rays emitted from the heater, and a metal film is formed on the surface of the X-ray target on the electron source side and inside the through holes. May be. Further, these through holes may have a tapered shape with a small hole on the surface on the transmission window side.

Further, the heater may be arranged on the surface opposite to the electron emission surface of the cathode, and a plurality of through holes may be formed in the electron emission surface of the cathode.

The material of the transparent window is Si (silicon).
Alternatively, it may be C (carbon) or Pyrex.

[0010]

According to the X-ray tube of the present invention, electrons are emitted by heating the cathode with a heater, and infrared rays are emitted from the heater at the same time when the electrons are emitted. The electrons emitted from the electron source collide with the X-ray target to generate X-rays, which are radiated in the transmission window direction. Further, the infrared rays emitted from the electron source pass through the X-ray target and proceed in the transmission window direction. And the X generated by the X-ray target
Infrared rays that have passed through the X-ray and X-ray targets pass through the transmission window and are emitted to the outside.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing the structure of an X-ray tube 1 according to this embodiment. An electron source 20 that emits electrons is attached to the end of the bottomed cylindrical envelope 10 made of glass. In front of it, cylindrical grid electrodes 30 to 33 for controlling the electron beam are sequentially arranged. With respect to the cathode 0 V (volt), the grid electrode 30 has -10 V, and the grid electrode 31 has 150 V.
(100V to 200V), 815 on the grid electrode 32
A potential of 0V and a potential of 8180V (or 8150V, which is the same potential as that of the grid electrode 32) are applied to the grid electrode 33, respectively.

In front of the grid electrode 32, a capillary plate type X-ray target 40 is attached by a holding metal fitting 41. A transmission window 50 having a high transmittance for X-rays and infrared rays is provided further in front of the grid electrode 33. The transparent window 50 is an In seal and the envelope 10
The inside of the envelope 10 is kept in a vacuum state.

The electron source 20 is provided with a capillary type cathode 21 having a plurality of through holes and a heater 22 for heating the cathode 21. Further, as the material of the transmission window 50, Si (silicon), C (carbon), Pyrex or the like is used.

As shown in the perspective view of FIG. 2A, the X-ray target 40 has a metal film 40b formed on one surface of a disk-shaped plate 40a having a plurality of through holes arranged on the surface thereof. It has a portion (a portion other than the through hole) that generates an X-ray upon incidence of an electron beam, and a portion (a portion of the through hole) that allows infrared rays emitted from the heater 22 to pass therethrough. The material of the plate 40a is Si (silicon), C
(Carbon), Pyrex, etc. are used. This kind of material is used for wavelengths that have high absorption by water.
This is because infrared rays of about μm can be transmitted and the X-ray transmittance is relatively high. The material of the metal film 40b is W (tungsten), Al (aluminum),
Metals such as Ca (calcium) are used.

Each through hole of the X-ray target 40 is shown in FIG.
As shown in (b), the hole on the electron source 10 side is large and the hole on the transmission window 50 side is small, and the metal film 40b is formed on the inner wall surface of the through hole. Since each through hole has such a tapered shape, the electron source 1
The electrons emitted from 0 collide with the surface portion (portion other than the through hole) of the X-ray target 40 to generate X-rays, and also collide with the metal film 40b inside the through holes to generate X-rays. . Therefore, the generation efficiency of X-rays is improved.

The X-ray target 40 is shown in FIG.
In addition to the shape described above, a metal film may be formed on one surface of the mesh-shaped plate.

Next, the operation of the X-ray tube 1 according to this embodiment will be described with reference to the perspective view of FIG. Heater 22
When is heated by energization, infrared rays are emitted. Due to the heating of the heater 22, electrons are emitted from the cathode 21 and travel toward the X-ray target 40. Also,
The infrared rays emitted from the heater 22 pass through the through hole of the cathode 21 and travel toward the X-ray target 40 in the same manner as the electrons.

The electrons emitted from the cathode 21 are sequentially accelerated by the grid electrodes 30 to 32, and the X-ray target 4
It collides with 0 at high speed. The metal film 40b formed on the X-ray target 40 receives an electron collision and emits a characteristic X-ray peculiar to the material. X-ray target 40 plate 40
Since a is made of a material that transmits X-rays such as Si (silicon), C (carbon), and Pyrex, the X-rays are transmitted in the direction of the transmission window 50 and radiated to the outside from the transmission window 50. In addition, the infrared rays that have passed through the through holes of the cathode 21 are
Further, the light passes through the through hole of the X-ray target 40 and is radiated to the outside from the transmission window 50.

By the above operation, X-rays and infrared rays are simultaneously emitted from the transmission window 50. Therefore, even when the object to be irradiated with X-rays contains water, the water is evaporated by the infrared rays, and it is possible to prevent a decrease in X-ray energy due to absorption of X-rays into water.

Next, a static eliminator using the X-ray tube 1 according to this embodiment will be described with reference to the configuration diagram of FIG. In this static eliminator, the charged object 81 to be neutralized is irradiated with an ionized gas flow to neutralize the object 81 to be neutralized. From the figure, this static eliminator comprises an X-ray tube 1 according to the present embodiment,
An ion generator 60 that ionizes air (or gas) by irradiation of X-rays from the X-ray tube 1 and an ion transporter 70 that sends out the ion gas generated by the ion generator 60 are provided. Further, it is provided with a neutralization unit 80 that neutralizes the object 81 to be neutralized by irradiation of the ion gas sent from the ion transport unit 70, and a control unit 90 that controls each processing unit.

The ion generator 60 of this static eliminator has an X
X-rays and infrared rays emitted from the ray tube 1 are given.
Therefore, the moisture in the air (or gas) of the ion generator 60 absorbs infrared rays and evaporates, so that the X-rays are not absorbed by the moisture.

In the conventional X-ray tube, since only X-rays are radiated, it is necessary to radiate X-rays of higher energy in consideration of a decrease in X-ray energy due to absorption of X-rays in water. I had to do it. As described above, the ionization rate is higher as the energy of the irradiated X-ray is lower, so that the ionization rate in the ion generation unit 60 is low in the conventional example. On the other hand, when the X-ray tube 1 according to the present embodiment is used, there is no fear that the X-ray energy will decrease, and it is possible to irradiate X-rays of low energy. Therefore, the ionization rate in the ion generator 60 is greatly improved as compared with the conventional example.

The grid electrode 33 in the X-ray tube 1 according to this embodiment is not an essential component of the present invention, and may have a structure without the grid electrode 33.

[0024]

According to the X-ray tube of the present invention, the electrons emitted from the cathode of the electron source collide with the X-ray target to generate X-rays.
A line is generated, and this X-ray is emitted toward the transmission window. Further, the infrared rays emitted from the heater of the electron source pass through the X-ray target and travel toward the transmission window. Then, the X-rays generated by the X-ray target and the infrared rays that have passed through the X-ray target are transmitted to the outside through the transmission window.

Therefore, even when the X-ray irradiation target contains water, the water can be evaporated by the infrared rays emitted at the same time as the X-rays, so that the absorption of X-rays by the water can be prevented.

Thus, even in the process of irradiating the air (or gas) with the X-rays emitted from the X-ray tube of the present invention to generate the ion gas, the influence of the X-ray absorption by the moisture of the air (or gas) Never receive. Therefore, it is possible to irradiate air (or gas) with low energy X-rays and improve the ionization rate.

Furthermore, by making the X-ray target a capital type in which a plurality of through holes are formed, infrared rays emitted from the heater can be efficiently transmitted. Further, by depositing metal up to the inner wall surface of the through hole, it is possible to supply reflective X-rays.

Similarly, when the cathode is a capital type having a plurality of through holes, it is possible to efficiently transmit the infrared rays of the heater. Further, the electron supply capability of the cathode is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an X-ray tube according to this embodiment.

FIG. 2 is a perspective view showing the structure of an X-ray target.

FIG. 3 is a perspective view showing a configuration of an X-ray tube according to the present embodiment.

FIG. 4 is a diagram showing a configuration of a static eliminator using an X-ray tube according to the present embodiment.

FIG. 5 is a cross-sectional view showing a configuration of an X-ray tube according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 10 ... Envelope, 20 ... Electron source, 21 ... Cathode, 22 ... Heater, 30-33 ... Grid electrode, 4
0 ... X-ray target, 40a ... Plate, 40b ... Metal film, 50 ... Transmission window, 60 ... Ion generating part, 70 ... Ion transporting part, 80 ... Eliminating part, 81 ... Electrified body, 90 ... Control part.

Claims (5)

[Claims] 1. An envelope, an electron source having an infrared radiation heater arranged in the envelope, and a cathode emitting electrons by heating of the heater, and an electron emission surface of the electron source. A transparent window provided on one surface of the envelope for transmitting X-rays and infrared rays, and arranged between the electron source and the transparent window, and the direction of the transparent window due to incidence of electrons emitted from the electron source. And an X-ray target having a portion for emitting X-rays and a portion for allowing infrared rays emitted from the heater to pass therethrough. 2. The X-ray target is formed with a plurality of through holes for passing infrared rays radiated from the heater, and the surface of the X-ray target on the electron source side and the inside of the through holes. The X-ray tube according to claim 1, wherein a metal film is formed on the X-ray tube. 3. The X-ray tube according to claim 2, wherein the through-hole of the X-ray target has a taper shape with a small hole on the surface on the transmission window side. 4. The heater according to claim 1, wherein the heater is disposed on a surface opposite to the electron emission surface of the cathode, and a plurality of through holes are formed on the electron emission surface of the cathode. The X-ray tube according to any one of 1. 5. The material of the transmission window is Si (silicon)
Alternatively, it is C (carbon) or Pyrex, and the X-ray tube according to any one of claims 1 to 4.