WO2018079946A1 - X-ray tube for improving electron focusing - Google Patents

Abstract

The present invention relates to "an X-ray tube for improving electron focusing" capable of guiding thermoelectrons discharged from a filament such that the thermoelectrons can efficiently move to a target on an X-ray irradiation window and reducing a proportion of impurities having been adsorbed in the filament. The X-ray tube for improving electron focus, proposed in the present invention, comprises: a non-conductive tubular pipe forming a body and having a hollow; the X-ray irradiation window which is formed so as to shield the upper end part of the tubular pipe, has a target coated thereon, and allows an X-ray to be irradiated therethrough; a stem part formed so as to shield the lower end part of the tubular pipe; a plurality of metal wires which extend towards the inside of the tubular pipe from the outside of the stem part and to which a predetermined negative high voltage is applied; the filament connected between the metal wires extending towards the inside of the tubular pipe, and discharging thermoelectrons; a first focusing tube encompassing the filament in order to focus the thermoelectrons discharged from the filament; and a cylindrical shield housing made of a conductive material and encompassing the outside of the tubular pipe, wherein the shield housing has the same voltage as the predetermined negative high voltage applied to the metal wires. The X-ray tube for improving electron focusing, proposed in the present invention, has the following advantages. 1. The thermoelectrons discharged from the filament can be efficiently moved to the target by providing an additional focusing tube at the lower part of the X-ray irradiation window. 2. The probability that gas-phased impurities are adsorbed on the filament (- voltage) located inside a focusing tube can be reduced by causing the impurities to be delaminated (released) from the target and adsorbed on the inner wall of the tubular pipe by the shield housing outside the tubular pipe, to which a negative voltage is applied, thereby enabling the life span of the filament to improve. 3. The probability that the thermoelectrons discharged from the filament can be moved to the X-ray irradiation window is to be improved by forming a shield wing part in the first focusing tube and dividing a space inside the tubular pipe into two.

Description

X-ray tube for electron focusing

The present invention relates to an X-ray tube for improving electron focus, and more specifically, to guide hot electrons emitted from a filament to be efficiently moved to a target of an X-ray irradiation window, and to reduce the specific gravity of adsorbed impurities on the filament. The present invention relates to an X-ray tube for improving electron focus.

In general, radiation having low permeability, which is easily absorbed even by a thin air layer according to material permeability, is called soft X-ray, and light having high permeability used for roentgen or the like is called light X-ray.

The energy of lead X-rays is about tenths lower than that of light X-rays, and much less by direct irradiation.

Table 1 shows the characteristics of the soft X-ray and light X-ray separately.

division	wavelength	energy	Usage
X-ray	1 ~ 10Å	1-10 keV	Analytical, Static Elimination
X-ray	0.01 ~ 1Å	10 ~ 1000keV	Medical, Industrial

As is known, since the soft X-ray of the soft X-ray generator is generated when the accelerated electrons collide with the metal target Be, the soft X-ray generator is composed of a high voltage generator and a target that accelerate the electrons at high speed.

When the voltage applied to the electrode is called a target voltage, the energy E is expressed by the following equation in the motion of electrons when colliding.

E = eV = (1/2) mv ²

here,

e: electronic charge amount (-1.602X10 ^-19 C)

e: electronic charge amount (-1.602X10 ^-19 C)

m: electron mass (9.109 X 10 ^-31 kg)

V: acceleration voltage

v: electron velocity.

As is known, the kinetic energy of the electron is mostly converted into heat when it collides with the target, and only about 1% of energy is emitted by the soft X-ray, and the soft x-ray generating efficiency is expressed as follows.

Generating Efficiency = 1.1X10 ^-9 ZV

Where Z is the atomic number of the target material.

The soft X-ray irradiation formula generates ions and electrons necessary for neutralization of the charge by generating photons of gas molecules and atoms around the charged object, and the characteristics of the soft X-ray irradiation formula are characterized by high concentration of ions and electrons. Since it can be generated, it is possible to remove static electricity in a short time, maintain a constant constant voltage of about 0 V, and it is widely used as an electrostatic removal because it can remove static electricity in an inert gas atmosphere at atmospheric pressure.

As is known, in the corona discharge type static eliminator, a separate blower is required for the transfer of ions, but the soft X-ray irradiated type static eliminator has an advantage of being able to discharge in an atmosphere without a wind condition.

In addition, since the soft X-ray radiation type static eliminator has a high energy (wavelength is about 1.3 kW or less), oxygen molecules or atoms can be ionized quickly, and thus, there is an advantage that almost no ozone is generated.

FIG. 1 shows an example of an X-ray tube connected to a high voltage generator and irradiated with soft X-rays among soft x-ion ionizers produced and marketed by the present applicant.

2 and 3 are further shown the front and rear views of the X-ray tube shown in FIG. 1 (for reference, there is a filament connected to the cobar wire in the cylindrical cathode serving as the focusing tube. Not shown).

As shown in FIG. 1, the X-ray tube includes a glass tube 100 and a metal target such as an X-ray radiating unit 200 (Be and W applied thereto) coupled to one end of the glass tube; And a stem portion 300 having glass or glass bonded to the other end portion of the glass tube 100 or a material having a physical chemical property equivalent thereto (hereinafter referred to as a glass material).

In addition, the X-ray tube shown in Figure 1 is a cylindrical cathode (also called a focusing tube 110), which serves to focus hot electrons emitted from the filament (not shown: installed inside the focusing tube), high voltage generator (shown And a conductive wire 120 (kovar wire) to which a voltage of about -1k to -60kV is applied, and a glass material interconnecting the conductive wire 120 inserted into the glass tube 100. Clip portion 130, one side is attached to the outside of the cylindrical cathode 110, the other side is in close contact with the inner wall of the glass tube 100, the guide spring 140 for supporting the cathode 110, the vacuum state inside the glass tube 100 It further comprises a component such as a getter (150) for maintaining the inside, the inside of the X-ray tube maintains a predetermined degree of vacuum controlled by a direct vacuum exhaust system.

The X-ray tube generally uses a focusing tube 110 having a cylindrical structure as shown in FIGS. 1 to 3 so that hot electrons emitted from the filament can efficiently move to the X-ray radiator 200.

By the way, the conventional X-ray tube which has such a structure has the following problems.

1. Despite the focusing tube, hot electrons emitted from the filament have low efficiency on the target

2. Due to hot electrons hitting the target, the gas-like impurities are separated from the target and charged with cations while colliding with other hot electrons. These impurities charged by the cations adsorb to the filament (-voltage) located inside the focusing tube. Thereby lowering the life of the filament.

The present invention has been proposed in order to solve the conventional problems, "electrons that can guide the hot electrons emitted from the filament to move efficiently to the target of the X-ray irradiation window and reduce the specific gravity of the adsorbed impurities in the filament An X-ray tube for focusing improvement "is provided.

The X-ray tube for improving electron focus according to the present invention forms a body and a non-conductive tube tube with a hollow formed thereon, and an X-ray irradiation window for irradiating X-rays formed to shield the upper end of the tube tube and having a target coated thereon; And a plurality of metal wires formed to shield the lower end of the tube tube and extending from the outside of the stem portion to the inside of the tube tube to which a predetermined negative high voltage is applied, and the metal extending into the tube tube. A filament connected between wires to emit hot electrons, a first focusing tube surrounding the filament to focus the hot electrons emitted from the filament, and a cylindrical shield housing made of a conductive material surrounding the outside of the tube tube, The shielding housing is equal to a predetermined negative high voltage applied to the metal wire. to be.

In the present invention, the tube is placed in the direction opposite to the first focusing tube, the lower portion located in the X-ray irradiation window is discharged from the first focusing pipe to the target of the X-ray irradiation window A cylindrical second focusing tube for focusing the hot electrons again is further provided.

In the present invention, the first focusing tube has a cylindrical shape in which a hollow for embedding the filament is formed, and an outer circumferential surface of the first focusing tube may be spaced apart from the inner wall of the tube.

In the present invention, the first focusing pipe is formed with a hollow for embedding the filament and the shielding wing formed on the outer circumferential surface of the first focusing pipe extends radially to contact the inner wall of the tube pipe and the shielding wing The inner space of the tube tube is separated into a first space that is an upper space of the shield wing and a second space that is a lower space of the shield wing.

In the present invention, the filament may extend in the horizontal direction.

When using the X-ray tube for improving electron focus proposed in the present invention has the following advantages.

1. By providing another focusing tube at the bottom of the X-ray irradiation window, hot electrons emitted from the filament can be efficiently moved to the target.

2. The life of the X-ray tube can be improved by reducing the probability that the gas-like impurities are adsorbed to the filament (-voltage) located inside the focusing tube due to hot electrons hitting the target. Can be extended.

1 to 3 are examples of conventional X-ray tubes.

4 to 6 are first to third embodiments of the X-ray tube for improving electron focus proposed in the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

For reference, in the technical terminology used herein, the term “X-ray irradiation window” is a metal target, a flange of stainless steel, and a metal flange sequentially connected to each other on top of a tube tube generally implemented in the art. It is to be understood and understood to mean collectively common components.

In addition, the X-ray tube described in the present invention is connected between the stem portion of the glass material having a substantially flat annular structure, a plurality of metal wires penetrating the edge of the glass stem portion, and the metal wire to perform the role of emitting hot electrons It further includes a filament, a cylindrical focusing tube for focusing hot electrons emitted from the filament, a getter joined to the outside of the focusing tube, and a cylindrical tube tube integrally connected to the hollow of the glass stem part. This configuration will be identified and described in advance that the configuration is known in the art for research and development of X-ray tube.

In addition, the metal material used as the filament of the present invention may include an alloy of W, W and Re (redium), an alloy of W and ThO 2 (thorium dioxide), and this is considered in consideration of thermal electron emission efficiency, filament durability, and the like. .

In addition, the stem portion of the glass material and the cylindrical tube tube material used in the present invention may include rod silicate glass, SiO 2 (quartz glass), UV Glass and the like.

Since the X-ray tube described above is generally widely used, additional descriptions thereof will be omitted, and embodiments of the present invention will be described below.

4 is a first embodiment of the X-ray tube for improving electron focus proposed in the present invention.

As shown, the electron focusing X-ray tube according to the first embodiment according to the present invention is formed to shield the upper end of the tube tube 100 and the non-conductive tube tube formed with a hollow and the tube formed, the target is applied An X-ray irradiation window 200 for irradiating the X-rays and a stem portion 300 are formed to shield the lower end of the tube tube.

X-ray tube for improving electron focus, which is a first embodiment of the present invention, includes a plurality of metal wires 400 extending from the outside of the stem portion 300 to the inside of the tube tube 100 and to which a predetermined negative high voltage is applied; A filament 500 is connected between the metal wires 400 extending inside the tube tube 100 to emit hot electrons, and a cylindrical shield housing 700 made of a conductive material surrounding the outside of the tube tube. .

For reference, the shielding housing 700 has a length capable of wrapping at least the stem portion 300 and the first focusing tube 600.

In the first embodiment of the present invention, the first focusing pipe 600 is a cylindrical shape in which the hollow for embedding the filament is formed, the outer peripheral surface of the first focusing pipe 600 is the inner wall of the tube pipe And a predetermined distance apart.

The operation of the first embodiment according to the present invention is as follows.

The hot electrons emitted from the filament are accelerated into the X-ray window and collide with the target constituting the X-ray window.

At this time, a part of the target is peeled off due to the collision with hot electrons, and gas-like impurities are generated inside the tube tube, and these impurities collide with other hot electrons emitted from the filament to carry cations. Some of the cationic impurities are adsorbed into the filament having the negative voltage, but in the present invention, some of the impurities of the cation because the cylindrical shielding housing of the conductive material surrounding the outside of the tube tube is maintained at the negative high voltage (the same voltage as the metal wire). Is adsorbed to the inner wall of the tube tube in contact with the shielding housing.

Accordingly, there is an advantage that the amount of impurities adsorbed into the filament can be reduced as compared with the conventional general X-ray tube without the shielding housing, and as a result, the life of the filament can be improved.

5 is a second embodiment of the X-ray tube for improving electron focus proposed in the present invention.

As shown, the electron focusing X-ray tube of the second embodiment according to the present invention is a non-conductive tube tube 100 and the hollow tube is formed as in the first embodiment and the tube tube 100 of the It is formed to shield the upper end and the X-ray irradiation window 200 for irradiating the X-ray to which the target is applied, and is formed to shield the lower end of the tube tube 100 is basically provided with a stem 300.

X-ray tube for improving electron focus according to the second embodiment of the present invention extends from the outer side of the stem portion 300 to the inner side of the tube tube 100 and a plurality of metal wires 400 to which a predetermined high voltage is applied, and the tube A first focusing filament 500 connected between the metal wires 400 extending inside the tube 100 to emit hot electrons and surrounding the filaments to focus the hot electrons emitted from the filament 500 The tube 600 and the tube tube 100 in the direction opposite to the first focusing tube 600 is disposed in the lower portion of the X-ray irradiation window 200 in the first focusing tube 600 A cylindrical second focusing tube 800 for re-focusing the hot electrons emitted to the target of the X-ray irradiation window 200 and a cylindrical shielding housing made of a conductive material surrounding the outside of the tube tube 100 ( And 700). For reference, the shielding housing 700 has a length capable of wrapping at least the stem portion 300 and the first focusing tube 600.

In the second embodiment of the present invention, the first focusing tube has a cylindrical shape in which a hollow for embedding the filament is formed, and an outer circumferential surface of the first focusing tube is spaced apart from the inner wall of the tube by a predetermined distance. .

For reference, in the second embodiment of the present invention, since the second focusing tube is formed, the length of the tube tube may be slightly longer than that of the first embodiment.

The operation of the second embodiment according to the present invention is as follows.

The hot electrons emitted from the filament located inside the first focusing tube pass through the first focusing tube and pass through the second focusing tube which is spaced a predetermined distance apart from the first focusing tube, and is located above the second focusing tube. It collides with the target constituting the line view window.

At this time, a part of the target is peeled off due to the collision with hot electrons, thereby generating gas-like impurities, and these impurities collide with other hot electrons emitted from the filament to form cations. Some of the cationic impurities can be adsorbed into the filament having a negative voltage, but in the present invention, since the cylindrical shield housing made of a conductive material surrounding the outside of the tube tube is maintained at the negative voltage, some of the cationic impurities are in contact with the shield housing. Is adsorbed to the inner wall of the tube.

Accordingly, there is an advantage that the amount of impurities adsorbed into the filament can be reduced as compared with the conventional general X-ray tube without the shielding housing, and as a result, the life of the filament can be improved.

In addition, in the second embodiment according to the present invention, by providing a second focusing tube, hot electrons passing through the first focusing tube can be efficiently accelerated to the X-ray irradiation window through the second focusing tube so that the X-ray of the X-ray tube Further investigations were made.

6 is a third embodiment of the X-ray tube for improving electron focus proposed in the present invention.

As shown, the X-ray tube for improving electron focus according to the third embodiment of the present invention, like the first and second embodiments, forms a body and has a hollow non-conductive tube tube 100 and the tube tube ( It is formed to shield the upper end of the 100 and the X-ray irradiation window 200 for irradiating the X-ray to which the target is applied, and is formed to shield the lower end of the tube tube 100 is basically provided with a stem portion 300 do.

X-ray tube for improving electron focus, which is a third embodiment of the present invention, extends from the outer side of the stem portion 300 to the inner side of the tube tube and includes a plurality of metal wires 400 to which a predetermined high voltage is applied, and the tube tube 100. A filament 500 connected between the metal wires 400 extending inwardly to emit hot electrons, a first focusing tube 600 surrounding the filament to focus the hot electrons emitted from the filament, and The tube is placed inside the tube in a direction opposite to the first focusing tube 600 but is positioned below the X-ray irradiation window 200 to be discharged from the first focusing tube 600 to the target of the X-ray irradiation window. A second cylindrical focusing tube 800 for focusing the hot electrons directed to the second and the cylindrical shielding housing 700 of a conductive material surrounding the outer side of the tube tube is further provided. For reference, the shielding housing 700 has a length capable of wrapping at least the stem portion 300 and the first focusing tube 600.

In the third embodiment of the present invention, unlike the first and second embodiments having the arc shape, the filament has a shape extending in the horizontal direction to improve the straightness of the hot electrons. The same applies to the second embodiment.

Unlike the first and second embodiments of the present invention described above, the first focusing tube according to the third embodiment of the present invention has a hollow for embedding the filament and is formed on the outer circumferential surface of the first focusing tube. The shield wing extends radially and contacts the inner wall of the tube tube.

Further, the tube tube is formed by the shielding wing portion of the first focusing tube between the first space between the upper surface of the shielding wing portion of the first focusing tube and the lower portion of the first focusing tube shielding wing and the stem portion under the second focusing tube. The separation into the second space, and the separation to prevent the hot electrons generated in the first space to move to the second space to improve the probability of moving the hot electrons in the first space to the X-ray irradiation window.

The operation of the third embodiment according to the present invention is as follows.

The hot electrons emitted from the filament located inside the first focusing tube pass through the first focusing tube and pass through the second focusing tube which is spaced a predetermined distance apart from the first focusing tube, and is located above the second focusing tube. It collides with the target constituting the line view window.

At this time, a part of the target is peeled off due to the collision with hot electrons, thereby generating gas-like impurities, and these impurities collide with other hot electrons emitted from the filament to form cations. Some of the cationic impurities can be adsorbed into the filament having a negative voltage, but in the present invention, since the cylindrical shield housing made of a conductive material surrounding the outside of the tube tube is maintained at the negative voltage, some of the cationic impurities are in contact with the shield housing. Is adsorbed to the inner wall of the tube.

Accordingly, there is an advantage that the amount of impurities adsorbed into the filament can be reduced as compared with the conventional general X-ray tube without the shielding housing, and as a result, the life of the filament can be improved.

In addition, in the case of the third embodiment according to the present invention, similarly to the second embodiment, by providing the second focusing tube, hot electrons passing through the first focusing tube can be efficiently accelerated to the X-ray irradiation window through the second focusing tube. In order to improve the X-ray irradiation ability of the X-ray tube, we tried to further improve.

In addition, in the third embodiment according to the present invention, the shielding wing formed on the outer circumferential surface of the first focusing tube extends radially to be in contact with the inner wall of the tube. The shielding wing upper space (first space) of the first focusing pipe is separated into the lower space (second space) of the shielding wing, and the thermal electrons emitted from the filament to the first space due to this space separation are transferred to the second space. By blocking the movement, the probability of moving the hot electrons in the first space to the X-ray irradiation window was improved.

In addition, in the third embodiment according to the present invention, the filament 500 is formed in the horizontal direction.

Here, the horizontal direction means a horizontal direction perpendicular to the longitudinal direction of the tube tube or the focusing tube.

In the conventional case, the filaments were formed in an arc-like type, and hot electrons were accelerated radially. However, in the present invention, the filaments are formed in a horizontal direction to improve the probability of hot electrons colliding directly with the target.

The X-ray tube for electron focusing improvement proposed by the present invention described so far has the following advantages.

1. By providing an additional focusing tube under the X-ray irradiation window, hot electrons emitted from the filament can be efficiently moved to the target.

2. Probability of being adsorbed to the filament (-voltage) located inside the concentrator tube by allowing gas-like impurities to be adsorbed on the inner wall of the tube tube by being separated (detached) from the target by a shielded housing applied as a negative voltage outside the tube tube. It is possible to improve the life of the filament by reducing the.

3. The shielding wing was formed in the first focusing tube to double the space inside the tube to improve the probability that hot electrons emitted from the filament can move to the X-ray irradiation window.

Claims (5)

1. A non-conductive tube tube forming a body and having a hollow, an X-ray irradiation window configured to shield an upper end of the tube tube and irradiating an X-ray to which a target is applied, and a stem formed to shield the lower end of the tube tube In the X-ray tube for improving electron focus provided with a portion,

   A plurality of metal wires extending from the outside of the stem to the inside of the tube and to which a predetermined negative high voltage is applied;

   A filament connected between the metal wires extending into the tube tube and emitting hot electrons;

   A first focusing tube surrounding the filament to focus the hot electrons emitted from the filament,

   Further comprising a shielding housing of a conductive material surrounding the outside of the tube tube,

   And said shielding housing is of the same voltage as a predetermined negative high voltage applied to said metal wire.
2. The method of claim 1,

   It is placed in the tube tube in a direction opposite to the first focusing tube, located in the lower portion of the X-ray irradiation window and emitted from the first focusing tube to focus again the hot electrons directed to the target of the X-ray irradiation window X-ray tube for improving the electron focus, characterized in that it further comprises a second focusing tube for.
3. The method according to claim 1 or 2,

   The first focusing tube has a cylindrical shape in which a hollow for embedding the filament is formed, and the outer circumferential surface of the first focusing tube is spaced apart from the inner wall of the tube tube by a predetermined distance. .
4. The method according to claim 1 or 2,

   The first focusing pipe is formed with a hollow for embedding the filament

   The shielding wing portion formed on the outer circumferential surface of the first focusing tube extends radially to contact the inner wall of the tube tube, and the inner space of the tube tube is the upper space of the shielding wing portion by the shielding wing portion and the shielding. X-ray tube for improving electron focus, characterized in that separated into the second space, the lower space of the wing.
5. The method of claim 4, wherein

   And said filament extends in a horizontal direction perpendicular to the longitudinal direction of said tube tube.

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