阅读说明：本技术 无氧铜外罩的软x射线管 (Soft X-ray tube with oxygen-free copper outer cover ) 是由 申云峰 柯炳育 申龙来 朱甫 胥广通 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种无氧铜外罩的软X射线管,包括发射X射线的放射端子、供X射线撞击并将其反射的阳极、约束X射线使其定向发射的集束管、设置于放射端子两端用于为其供电的导电杆,其特征在于,阳极完全裸露在外部,导电杆的位置设置有作为阴极固定底座存在的陶瓷绝缘子,陶瓷绝缘子上开设有贯通孔,导电杆通过贯通孔穿过陶瓷绝缘子,阳极与陶瓷绝缘子之间设置有外罩,外罩与陶瓷绝缘子之间设置有用于连接两者的可伐接头,通过改变可伐接头的长短可以改变阳极与陶瓷绝缘子的间距。本发明的有益效果是,本发明将常规X射线管的阳极直接暴露在空气中,通过大面积的与空气接触,从而实现靶极热量的快速散出,从而避免因热量聚集而加速老化。(The invention discloses a soft X-ray tube with an oxygen-free copper outer cover, which comprises a radiation terminal for emitting X-rays, an anode for impacting and reflecting the X-rays, a bundling tube for restraining the X-rays to be emitted directionally, and conductive rods arranged at two ends of the radiation terminal and used for supplying power to the radiation terminal. The invention has the advantages that the anode of the conventional X-ray tube is directly exposed in the air and is contacted with the air in a large area, so that the heat of the target is rapidly dissipated, and the accelerated aging caused by heat accumulation is avoided.)

1. A soft X-ray tube with an oxygen-free copper outer cover (7) comprises a radiation terminal (1) for emitting X-rays, an anode (2) for X-rays to collide and reflect, a beam concentration tube (3) for restraining the X-rays to be emitted in a directional manner, and a conductive rod (4) arranged at two ends of the radiation terminal (1) and used for supplying power to the radiation terminal, and is characterized in that the anode (2) is completely exposed outside, a ceramic insulator (5) serving as a cathode fixing base is arranged at the position of the conductive rod (4), a through hole (6) is formed in the ceramic insulator (5), the conductive rod (4) penetrates through the ceramic insulator (5) through the through hole (6), the outer cover (7) is arranged between the anode (2) and the ceramic insulator (5), and a kovar joint (8) for connecting the outer cover (7) and the ceramic insulator (5) is arranged between the outer cover (7) and the ceramic insulator (, the distance between the anode (2) and the ceramic insulator (5) can be changed by changing the length of the kovar joint (8).

2. The soft X-ray tube of an oxygen-free copper housing (7) according to claim 1, wherein the anode (2) is made of an oxygen-free copper material, the housing (7) is made of an oxygen-free copper material, the collector tube (3) is a nickel collector tube (3), and the conductive rod (4) is a nickel conductive rod (4).

3. The soft X-ray tube with an oxygen-free copper housing (7) according to claim 1, wherein the anode (2) has a cylindrical shape, and a fixing plug (9) for facilitating the external heat dissipation of the anode (2) is disposed on the end surface of the anode (2) to improve the heat dissipation capability of the anode (2).

4. The soft X-ray tube of an oxygen-free copper housing (7) according to claim 1, characterized in that the anode (2) and the housing (7) are in the shape of a comb-toothed sheet structure.

5. The soft X-ray tube with the oxygen-free copper outer cover (7) as claimed in claim 1, wherein a hollow groove is formed in the side face of the outer cover (7), a platinum window (701) is arranged in the hollow groove, a support rod (702) convenient for fixing the platinum window (701) is arranged between the platinum window (701) and the outer cover (7), and a vacuum exhaust pipe (703) used for exhausting air from the tube cavity is formed in the side face of the outer cover (7) and in the position opposite to the platinum window (701).

6. The soft X-ray tube of an oxygen-free copper housing (7) according to claim 1, characterized in that the position where the electrode rod contacts the outer end face of the ceramic insulator (5) is provided with a disc (601), which disc (601) is capable of supporting the electrode rod firmly on the ceramic insulator (5).

7. The soft X-ray tube with oxygen-free copper envelope (7) according to claim 1, characterized in that the target of the anode (2) is a gold-plated target and the radiation terminal (1) is a ring-shaped tungsten filament.

Technical Field

The invention relates to the field of electron ray tubes, in particular to a soft X-ray tube with an oxygen-free copper outer cover.

Background

The principle of a soft X-ray tube is that when thermal electrons generated by a heated tungsten filament are accelerated by the tube voltage and strike the target, X-rays are generated. If the velocity at the instant of collision of the accelerated electrons is v, the kinetic energy of the electrons is 1/2mv2, and at the instant of stop of collision of the accelerated electrons, this kinetic energy is converted into X-rays and thermal energy, and the relationship "kinetic energy is 1/2mv2 ═ X-ray energy + thermal energy" is established. In the ordinary acceleration voltage range (150kv or less) for medical diagnosis, about 1% of the energy of an incident electron beam is converted into X-rays, 99% of the energy is converted into heat energy, and only a part of the generated X-rays is emitted within an available irradiation angle.

In the prior soft X-ray tube structure for eliminating static electricity, a target electrode on the inner surface of a beryllium window is made of gold-plated material and generates X-rays in the same direction as an electron beam. Although such a structure can increase the irradiation angle, the X-ray transmittance limits the thickness of the gold-plated target, which affects the durability of the target. When X-rays are generated, part of heat generated on the gold-plated target electrode on the inner surface of the beryllium window is discharged to the outside through the window, and the rest heat is transferred to the beryllium window supporting rod and is dissipated through the outer surface.

Disclosure of Invention

The invention aims to solve the problems that the existing structure is low in heat dissipation efficiency and easy to age the whole structure, and designs a soft X-ray tube with an oxygen-free copper outer cover.

The technical scheme of the invention is that the soft X-ray tube with the oxygen-free copper outer cover comprises a radiation terminal for emitting X-rays, an anode for impacting and reflecting the X-rays, a beam tube for restraining the X-rays to be emitted directionally, and conductive rods arranged at two ends of the radiation terminal and used for supplying power to the radiation terminal, wherein the anode is completely exposed outside, a ceramic insulator serving as a cathode fixing base is arranged at the position of the conductive rods, a through hole is formed in the ceramic insulator, the conductive rods penetrate through the ceramic insulator through the through hole, the outer cover is arranged between the anode and the ceramic insulator, a kovar joint for connecting the outer cover and the ceramic insulator is arranged between the outer cover and the ceramic insulator, and the distance between the anode and the ceramic insulator can be changed by changing the length of the kovar joint.

In order to exert the highest performance of each part, the anode is made of an oxygen-free copper material, the outer cover is made of an oxygen-free copper material, the bundling tube is a nickel bundling tube, and the conducting rod is a nickel conducting rod.

In consideration of the possibility that heat is urgently needed to be dissipated or the temperature is kept low in practical use, the anode is cylindrical, and the end face of the anode is provided with a fixing plug which is convenient for being externally connected with a heat dissipating piece so as to improve the heat dissipating capacity of the anode.

As another embodiment of the outer cover structure, in order to enhance the heat dissipation performance, the outer shapes of the anode and the outer cover are comb-teeth-shaped sheet structures.

Besides the basic structure, the structure also comprises a structure that a hollow groove is formed in the side surface of the outer cover, a platinum window is arranged in the hollow groove, a supporting rod convenient for fixing the platinum window is arranged between the platinum window and the outer cover, and a vacuum exhaust pipe used for exhausting gas in the pipe cavity is arranged on the side surface of the outer cover and at the position opposite to the platinum window.

And a disc is arranged at the position where the electrode rod is contacted with the outer end face of the ceramic insulator, and the disc can support the electrode rod to enable the electrode rod to be stable on the ceramic insulator.

In order to improve the X-ray quantity and accelerate the heat transfer, the target electrode of the anode adopts a gold-plated film target electrode, and the radiation terminal is an annular tungsten filament.

The invention has the beneficial effects that 1, the anode of the conventional X-ray tube is directly exposed in the air and is contacted with the air in a large area, so that the heat of the target is rapidly dissipated, and the accelerated aging caused by heat accumulation is avoided.

2. In the aspect of material selection, the gold target is selected as the target material, the gold material can excite more X rays, and meanwhile, the gold target has the characteristic of higher heat dissipation performance, and the power efficiency is improved by matching with the rapid heat dissipation performance of the product structure.

3. The outer cover and the ceramic insulator are connected through the kovar joint, the length of the kovar joint can be changed, and by utilizing the kovar joint, the distance between the outer cover and the ceramic insulator can be adjusted, the relative position of the anode target and the outer cover is fixed, and the relative position of the cathode emission terminal and the ceramic insulator is fixed, so that the distance between the anode target and the cathode emission terminal is adjusted in a phase-changing manner, and the adjustment of the X-ray excitation distance is further realized.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of the structure of the heat dissipation structure of the present invention;

FIG. 3 is a schematic diagram of a prior art X-ray tube;

FIG. 4 is a schematic view of another prior art X-ray tube configuration;

FIG. 5 is a flow chart of the structural assembly of the present invention;

in the figure, 1, a radiation terminal; 2. an anode; 3. a bundling tube; 4. a conductive rod; 5. a ceramic insulator; 6. a through hole; 601. a disc; 7. a housing; 701. a platinum window; 702. a support bar; 703. a vacuum exhaust pipe; 8. a kovar joint; 9. and fixing the plug.

Detailed Description

In order to make the technical point of the present invention clear to those skilled in the art, the following description will first explain the structural principle of the conventional X-ray tube to illustrate the advantages of the present invention by the difference between the two.

X-rays are generated when thermal electrons generated from a heated tungsten filament strike the target after acceleration by the tube voltage. If the velocity at the instant of collision of the accelerated electrons is v, the kinetic energy of the electrons is 1/2mv, and at the instant of stop of collision of the accelerated electrons, this kinetic energy is converted into X-rays and thermal energy, and the relationship "kinetic energy is 1/2mv ═ X-ray energy + thermal energy" is established. In a general medical diagnosis process, the acceleration voltage range is below 150kv, about 1% of the energy of incident electron beams is converted into X-rays, and 99% of the energy is converted into heat energy. And only a portion of the generated X-rays are emitted into the available angle of irradiation. In the laboratory, the efficiency of conversion to X-rays can reach 40% or more under high energy acceleration in MV units. When the accelerated electrons collide with the target, they do not lose all their energy instantaneously but release it through several stages, each of which emits X-rays of a corresponding arbitrary frequency to produce a continuous spectrum. The relationship between the maximum frequency of the generated X-ray spectrum and the acceleration voltage is as follows.

eV＝hυ_M＝(1/2)mv²,υ_M＝V/(12.40×10³)

υ_MMaximum frequency of X-rays

h: frank constant

V: electronic (e) acceleration voltage (tube voltage)

V: velocity of the electrons

m: mass of the electrons

The amount of X-rays generated is positively correlated with the atomic number of the target material, and when an electron beam strikes the target in a high-power X-ray tube, a large amount of heat is generated at the focal point, which tends to cause damage to the target, so that the heat capacity, thermal conductivity, melting point, and the like of the target material are important considerations for analyzing whether the material is suitable as a target, in addition to the atomic number of the target material. Therefore, tungsten (W) or a tungsten alloy having a high melting point and an atomic number of 74 is generally used as the target material. When gold (Au) having an atomic number of 79 is used as a target material, the amount of X-ray generation increases by about 7% compared to tungsten having an atomic number of 74 under the same acceleration energy condition.

The X-ray generation amount is also related to the tube current and the tube voltage, and if the tube voltage is increased, the X-ray generation amount is increased by the square proportion of the voltage and is generated according to different target electrode materialsCharacteristic line, the generated X-ray spectrum shifts to the high energy direction. Amount of X-ray generated (I)_int.) Reference is made to the following formula.

I_int.∝iZV^b

i: tube current

Z: atomic number

V: accelerating voltage (tube voltage)

b: arbitrary constant (2)

The basic principle features of a conventional soft X-ray tube are explained above, and the detailed structure thereof will be explained with reference to fig. 3 to 4.

The conventional soft X-ray tube for eliminating static electricity has the structure shown in fig. 3 and 4, and the target on the inner surface of the beryllium window in the structure shown in fig. 4 is made of gold-plated material and generates X-rays in the same direction as the electron beam. On the one hand, although the irradiation angle can be increased, the thickness of the gold-plated target is limited due to the penetration rate of the X-rays (the target is thinner, and if the gold-plated target is too thick, the X-rays cannot penetrate through the target), and the thinner thickness affects the durability of the target; on the other hand, the heat generated on the gold-plated target electrode on the inner surface of the beryllium window when X-rays are generated is only partially discharged to the outside through the window, and the rest of the heat is transferred to the beryllium window support bar 702 and dissipated through the outer surface, but the conventional structure has a disadvantage that the target electrode is damaged by heat in an accelerated manner because the beryllium window support bar 702 has low thermal conductivity.

The configuration of fig. 3 utilizes X-rays emitted at 90 degrees to the electron beam. Although this structure has an advantage of improving the durability of the target, it has a disadvantage of a small irradiation angle (about 40 degrees), and has a disadvantage of failure due to the structure of the anode 2 when continuously used, because the heat accumulated in the anode cannot be discharged to the outside in time, and the entire temperature rises. In addition, the cover 7 of the structure shown in fig. 3 and 4 is made of glass, and has a disadvantage of weak impact resistance.

In order to avoid the above-mentioned drawbacks of the prior art, a specific structure of the present invention is described as follows:

in order to realize the improvement of the existing structure, the invention carries out the transformation on the existing structure in three aspects, which mainly comprises the following steps:

1. the anode 2 is exposed to the outside, thereby facilitating self heat dissipation.

2. Replacing the glass envelope 7 with an oxygen free copper envelope 7 increases the impact resistance.

3. All parts are assembled by vacuum brazing, and a reproducible process is established.

The anode 2 of the invention adopts the oxygen-free copper anode 2, the anode 2 is directly exposed in the air, the rapid heat dissipation of the temperature of the anode 2 is realized by utilizing the characteristic that the surface of the anode 2 is directly contacted with the air, the main body of the oxygen-free copper anode 2 is a cylindrical structure with a circular truncated cone at the upper part and a cylindrical lower part, a convex structure is arranged at the center position of the bottom surface of the cylindrical structure, an inclined target pole is formed at the tail end of the convex part, and on the basis of the structure, a fixing plug 9 is also arranged on the top end surface of the circular truncated cone of the oxygen-free copper anode 2, and a heat-proof accessory can be additionally arranged if necessary to accelerate the heat dissipation of the target pole.

The cathode structure of the invention is the same as the structure of the existing product, and both consist of a bundling tube 3 and a ceramic insulator 5, an annular tungsten filament is arranged in the bundling tube 3, the annular tungsten filament is a core component for releasing X-rays, in order to electrify the annular tungsten filament, nickel electrode rods are arranged at two ends of the annular tungsten filament, the annular tungsten filament is connected with the nickel electrode rods through a support rod 702, a through hole 6 is arranged in the middle of a ceramic insulator 5, the nickel electrode rods penetrate through the through hole 6 to be connected with an external electrode, and a disc 601 is fixed at the contact part of the nickel electrode rod and the outer bottom surface of the ceramic insulator 5 for enhancing the firmness of the nickel electrode rod, the annular tungsten filament is connected with a nickel electrode rod through electric welding and then assembled on the nickel bundling tube 3, the nickel electrode rod is brazed with the disc 601, and molybdenum paste is needed to be used for metallization treatment at the brazed place.

The anode 2 structure and the cathode structure of the product of the invention are described above, and then the anode 2 structure and the cathode structure need to be connected into a whole, the structure for connecting the anode 2 and the cathode is the annular outer cover 7 arranged between the anode 2 structure and the cathode structure, and the outer cover 7 is also made of oxygen-free copper material so as to discharge the heat generated at the focus of the target outward through the anode 2. Also can produce the inside heat of X-ray tube when heating tungsten filament except that the target focus, most heat that tungsten filament produced also will be through 7 heat conduction of dustcoat and outwards discharge rapidly, and the material is done to the strong oxygen-free copper of heat conductivity has all been selected for use to positive pole 2 and dustcoat 7, can guarantee that the difference in temperature between them falls to minimumly.

It is considered that the X-rays generated on the target require a specific window to be emitted to the outside. Therefore, a window is opened on one side surface of the annular housing 7, a platinum window 701 is arranged at the position of the window, the platinum window 701 and the window of the housing 7 are connected through a support rod 702, and the beryllium window is formed by brazing a beryllium foil disc 601 which transmits X-rays on the window support rod 702. The X-ray generated in the soft X-ray tube for static elimination has low energy in the soft X-ray field, and it is necessary to use beryllium foil of 0.12t as a transmission window, and the irradiation angle in the soft X-ray tube for static elimination is a very important parameter depending on the size of the beryllium window and the distance between the beryllium window and the target focus, so the size of the platinum window 701 and the thickness of the window support rod 702 are very important structures.

It is contemplated that a vacuum environment may be maintained within the enclosure 7to ensure proper X-ray excitation. Therefore, the other side surface of the annular outer cover 7 is provided with a through hole for communicating the inner space and the outer space of the outer cover 7, and the through hole is provided with the vacuum exhaust pipe 703. the use method is that after the integral structure of the invention is assembled, the through hole where the vacuum exhaust pipe 703 is located is used for exhausting air to ensure that the inner space of the X-ray tube is vacuum, and then the vacuum exhaust pipe 703 is installed to seal the through hole. Besides the above functions, the vacuum exhaust pipe 703 can facilitate later maintenance of the X-ray tube, avoid the disassembly and damage of the housing 7, and reduce the maintenance cost.

The structure of the outer cover 7 has been described in detail above, and the connection mode between the outer cover 7 and the cathode will be described below, wherein the kovar joint 8 is arranged between the outer cover 7 and the cathode, the kovar joint 8 is an annular thin sheet, and the distance between the anode 2 and the cathode can be changed by increasing or decreasing the length of the kovar joint 8, so as to adjust the distance between the X-ray from the annular tungsten filament to the target.

To explain the necessity of the platinum window 701, the X-ray tube of the present invention has an output of about 5W, an accelerating voltage of about 10kv, and is not limited by the problem of damage due to heat generated from the focal point of the target, and therefore, the target material can be freely selected, and a gold (Au) plated target is used here. An acceleration voltage with corresponding wavelength is required to be input for generating the soft X-ray, and the acceleration voltage is about 10kv, so that the energy of the generated X-ray is small and the X-ray cannot penetrate through an external structure such as a glass outer cover 7, and a beryllium window is required on the structure of the X-ray tube.

So far, the overall structure of the oxygen-free copper housing 7 soft X-ray tube according to the invention has been described, and in addition to this structure, the invention provides another structural way:

as shown in fig. 2, the outer surfaces of the anode 2 and the outer cover 7 are arranged in a comb-teeth-shaped heat sink structure, so that the heat dissipation contact area of the anode 2 and the air is increased, and the heat dissipation efficiency of the anode 2 can be further improved.

The above description explains the components, and how the X-ray tube according to the present invention is assembled into a finished product, the specific assembly process is as follows:

the respective parts and the entire assembly are formed by brazing, and the sequence thereof is shown in fig. 5. Firstly, the ceramic insulator 5 is metalized, molybdenum metallization is carried out on the positions of all parts brazed on the ceramic insulator 5, a kovar joint 8 is brazed on one side of the ceramic insulator 5, a nickel electrode rod penetrates through a through hole 6 in the ceramic insulator 5, an electrode rod supporting disc 601 is arranged at the tail end of the nickel electrode rod, and the electrode rod supporting disc 601 and the ceramic insulator 5 are brazed and connected.

Before the support rod 702 is spot-welded to the other end of the nickel electrode rod, the nickel electrode rod and the cathode portion including the annular filament, the support rod 702 and the tube 3 are assembled in such a manner that the annular filament is spot-welded to the support rod 702, the tube 3 is fixedly attached to the support rod 702, and the support rod 702 to which the annular filament and the tube 3 are attached is spot-welded to the other end of the nickel electrode rod.

Thereafter, a gold (Au) film is plated on the inclined target of the oxygen-free copper anode 2.

Next, a kovar joint 8 is brazed to the base of the ceramic insulator 5, an oxygen-free copper cover 7 is brazed to the kovar joint 8, and an oxygen-free copper anode 2 is brazed to the oxygen-free copper cover 7.

Then, a beryllium window is opened at the upper end of the oxygen-free copper cover 7, a beryllium window support bar 702 is soldered to the upper end of the oxygen-free copper cover 7, and a beryllium window made of beryllium foil is soldered to the beryllium window support bar 702. Finally, the vacuum exhaust pipe 703 is evacuated to make the interior vacuum state, then the vacuum exhaust pipe 703 is sealed, when the assembly is completed, the basic vacuum degree reaches-10-9 torr, then the baking is carried out, and when the vacuum degree reaches-10-7 torr, the sealing is carried out.

In order for the person skilled in the art to believe the authenticity of the product according to the invention, it is explained below by the actual measured values of the invention under certain specific conditions:

experimental measurement 1. operating conditions were: the nickel electrode rod of the cathode part is applied with a tube voltage of-10 Kv (according to the requirement of static elimination, the voltage of-9 Kv to-11 Kv is input on the nickel electrode rod of the cathode of the invention), the tube current is 0.7mA, the filament heating voltage is 6V, and the filament heating current is 0.9A.

In the indoor atmosphere, the X-ray quantity was measured by a measuring instrument at a position 1m from the beryllium window. The measured X-ray dose is central (0 degrees): 30000 mR/hr; 20 degrees: 25000 mR/hr; 35 degrees: 20000 mR/hr; above 35 degrees the taper is reduced by a few thousand mR/hr (i.e. angles greater than 35 degrees are no longer applicable). From the measured data, it was confirmed that the irradiation angle of the present invention was 70 degrees (35 degrees on the left and right).

Experiment measurement 2. the operation conditions are that tube voltage of-10 Kv, tube current of 0.7mA, filament heating voltage of 6V and filament heating current of 0.9A are added on the electrode rod of the cathode part.

The temperature change of the anode 2 at various time periods after the operation was measured at room temperature of 20 c. And (3) measuring results: (the temperature difference between the anode 2 and the housing 7 is less than 0.25 ℃ and the default is the same here) the values are as follows:

if a heat-proof fitting is additionally installed on the fixing plug 9 of the anode 2 or the anode 2 and the outer cover 7 are made into a heat-radiating fin type heat-proof structure, the temperature can be reduced to below 40 ℃.

The technical solutions described above only represent the preferred technical solutions of the present invention, and some possible modifications to some parts of the technical solutions by those skilled in the art all represent the principles of the present invention, and fall within the protection scope of the present invention.