阅读说明：本技术 可调节的冷阴极x射线管 (Adjustable cold cathode X-ray tube ) 是由 刘宇荣 李永明 王少哲 葛锐 李晨辉 黄浩 于 2020-06-16 设计创作，主要内容包括：本发明公开了一种可调节的冷阴极X射线管,包括上瓷管和下瓷管,下瓷管下端设有阳极部件,上瓷管和下瓷管之间设有栅极,上瓷管内设有冷阴极和聚焦极,冷阴极和聚焦极相对栅极之间的距离均可单独调节。本发明可通过调节聚焦极和阴极在轴向的位置,即可实现多种电压条件下工作,从而得到不同短波限的X射线；同样,通过调节聚焦极和阴极在轴向的位置,可在相同或不同工作电压下得到不同大小的阳极电流,从而得到不同的短波限和不同强度的X射线,不仅操作简单,具有更方便调整电子束流汇聚作用,而且调整范围更大,有利于形成更小焦点,同时该冷阴极X射线管的结构能够优化老炼过程,提升产品的良率。(The invention discloses an adjustable cold cathode X-ray tube, which comprises an upper ceramic tube and a lower ceramic tube, wherein the lower end of the lower ceramic tube is provided with an anode part, a grid is arranged between the upper ceramic tube and the lower ceramic tube, a cold cathode and a focusing electrode are arranged in the upper ceramic tube, and the distance between the cold cathode and the focusing electrode relative to the grid can be independently adjusted. The invention can realize the work under various voltage conditions by adjusting the axial positions of the focusing electrode and the cathode, thereby obtaining X-rays with different short wave limits; similarly, by adjusting the axial positions of the focusing electrode and the cathode, anode currents with different sizes can be obtained under the same or different working voltages, so that different short wave limits and X rays with different intensities can be obtained.)

1. The utility model provides a cold cathode X-ray tube with adjustable, includes ceramic tube (1a) and lower ceramic tube (1b), ceramic tube (1b) lower extreme is equipped with anode part (2) down, go up ceramic tube (1a) and be equipped with grid (3) down between ceramic tube (1b), upward be equipped with cold cathode (4) and focus utmost point (5), its characterized in that in ceramic tube (1 a): the distance between the cold cathode (4) and the focusing electrode (5) relative to the grid electrode (3) can be independently adjusted.

2. An adjustable cold cathode X-ray tube according to claim 1, wherein: a cathode flange (6) is arranged at an opening at the top of the upper ceramic tube (1a), a focusing electrode bottom plate (8) is additionally arranged, the focusing electrode (5) is cylindrical and is arranged in the upper ceramic tube (1a), and the top of the focusing electrode (5) movably penetrates through the cathode flange (6) and is fixedly connected with the focusing electrode bottom plate (8); a plurality of adjusting lugs (9) extending outwards are arranged on the focusing electrode base plate (8), each adjusting lug (9) is provided with a first through hole (91), a focusing electrode adjusting screw (10) is arranged in each first through hole (91), a first adjusting threaded hole (61) is correspondingly arranged on the cathode flange (6), and a locking nut (7) is sleeved at the threaded end of each focusing electrode adjusting screw (10) and then screwed into the first adjusting threaded hole (61); and the focusing electrode (5) is positioned outside the part between the cathode flange (6) and the focusing electrode bottom plate (8) and is respectively provided with an outer corrugated pipe (11) and an inner corrugated pipe (12), and the upper end and the lower end of the outer corrugated pipe (11) and the upper end and the lower end of the inner corrugated pipe (12) are respectively fixed on the cathode flange (6) and the focusing electrode bottom plate (8).

3. An adjustable cold cathode X-ray tube according to claim 2, wherein: and the center of the focusing electrode bottom plate (8) is provided with an adjusting hole (81).

4. An adjustable cold cathode X-ray tube according to claim 3, wherein: the cold cathode (4) is arranged on a cathode base (13), the cathode base (13) can be arranged in the bottom of the focusing electrode (5) in a vertically sliding mode, and the upper end of the cathode base (13) is fixedly connected with the cathode flange (6) through a central corrugated pipe (14); the center of the cathode flange is provided with a second threaded through hole (62), the center of the upper side face of the cathode base (13) is provided with a limiting groove (16), a cathode adjusting screw (15) is additionally arranged and penetrates through the second threaded through hole (62) in the cathode flange (6) to the limiting groove (16) in the cathode base (13) through threaded engagement, and the cathode adjusting screw (15) can radially rotate and axially stop relative to the limiting groove (16).

5. An adjustable cold cathode X-ray tube according to claim 4, wherein: the cold cathode (4) comprises a substrate and a coating layer coated on the substrate, wherein the base material of the substrate is metal or alloy containing iron and nickel, and the coating layer is a carbon nano tube or graphene.

6. An adjustable cold cathode X-ray tube according to claim 4, wherein: the tail end of the cathode adjusting screw (15) is provided with a limiting boss, a limiting groove is correspondingly arranged in the limiting groove (16), and the limiting boss is clamped in the limiting groove.

7. An adjustable cold cathode X-ray tube according to claim 2, wherein: the adjusting lugs (9) are at least two and are uniformly arranged on the periphery of the focusing pole bottom plate (8).

8. An adjustable cold cathode X-ray tube according to claim 2, wherein: and a positioning groove (82) is formed in the focusing electrode bottom plate (8), and the top of the focusing electrode (5) penetrates into the positioning groove.

9. An adjustable cold cathode X-ray tube according to claim 2, wherein: the anode part (2) comprises an anode (21) and a target (22) arranged on the anode.

Technical Field

The invention relates to the technical field of field emission and the field of electric vacuum devices, in particular to an adjustable cold cathode X-ray tube.

Background

Field emission technology: when a certain electric field is applied to the coating layer of the field emission cathode substrate, a part of high-energy electrons near the Fermi level can cross the potential barrier on the surface of the cathode due to the tunneling effect, and then the electrons overflow the surface and fly to the anode to form current. The process does not need extra energy to excite electrons, and has the characteristics of quick response, small energy loss, high emission efficiency and the like.

Although field emission cathodes have shown excellent performance and great potential for development as X-ray tube electron sources, there are many problems to be solved. Such as: the coating layer material on the surface of the cathode is not only graphene or carbon nano tube, but also is easily affected by external factors in the growth process, the growth uniformity is difficult to ensure, and the current emission density of each cold cathode is inconsistent; secondly, the long-time working stability of the cold cathode ray tube needs to be improved. On one hand, the cold cathode has a small diameter, so that the contact area of the coating layer and the substrate is small, poor contact is caused at the joint, the resistance at the joint is increased, and the heat generated during continuous operation can possibly cause the damage of part of the coating layer. On the other hand, secondary electron back-bombardment may be generated in a long-time working process, which also causes continuous accumulation of heat, and finally burns out the surface coating layer, so that the emission current density is reduced, the number of electrons generated by the electron beam striking the target material is reduced, and the output power is reduced. Under the conditions, the focal spot size needs to be adjusted, so that more electron beams are gathered and hit on the target material, and the stability of the output power is ensured.

Generally, an X-ray tube only works in a narrow working voltage range, namely the adjustable range of the working voltage is too small, the short wave limit of the generated X-rays is basically fixed, the working efficiency of the whole machine is limited, and the multiple purposes of one machine are difficult to realize under the condition of one X-ray tube.

Disclosure of Invention

In order to make up for the defects of the prior art, the invention provides the adjustable cold cathode X-ray tube which is simple to operate, has the function of conveniently adjusting the convergence of electron beams, has a larger adjustment range, is beneficial to forming a smaller focus on one hand, and can realize the change of working voltage in a larger range or the change of different currents under the same voltage on the other hand, and meanwhile, the structure of the cold cathode X-ray tube can optimize the aging process and improve the reliability of products.

The technical scheme adopted by the invention for solving the technical problem is as follows: the utility model provides a cold cathode X-ray tube with adjustable, includes ceramic cylinder and lower ceramic cylinder, the ceramic cylinder lower extreme is equipped with the anode part down, go up the ceramic cylinder and be equipped with the grid down between the ceramic cylinder, it is equipped with cold cathode and focus utmost point to go up in the ceramic cylinder, cold cathode and focus extremely relatively the equal independent control of distance between the grid.

As a further improvement of the invention, a cathode flange is arranged at the top opening of the upper ceramic tube, a focusing electrode bottom plate is additionally arranged, the focusing electrode is cylindrical and is arranged in the upper ceramic tube, and the top of the focusing electrode movably penetrates through the cathode flange and is fixedly connected with the focusing electrode bottom plate; a plurality of adjusting lugs extending outwards are arranged on the focusing electrode bottom plate, each adjusting lug is provided with a first through hole, a focusing electrode adjusting screw is arranged in each first through hole, a first adjusting threaded hole is correspondingly arranged on the cathode flange, and a locking nut is sleeved at the threaded end of each focusing electrode adjusting screw and then screwed into the first adjusting threaded hole; and the focusing electrode is provided with an outer corrugated pipe and an inner corrugated pipe outside the part between the cathode flange and the focusing electrode base plate, and the upper end and the lower end of the outer corrugated pipe and the upper end and the lower end of the inner corrugated pipe are respectively fixed on the cathode flange and the focusing electrode base plate.

As a further improvement of the invention, the center of the focusing electrode bottom plate is provided with an adjusting hole.

As a further improvement of the invention, the cold cathode is arranged on a cathode base, the cathode base can be arranged in the bottom of the focusing electrode in a vertically sliding manner, and the upper end of the cathode base is fixedly connected with the cathode flange through a central corrugated pipe; the center of the cathode flange is provided with a second threaded through hole, the center of the upper side face of the cathode seat is provided with a limiting groove, a cathode adjusting screw is arranged in addition and penetrates through the second threaded through hole in the cathode flange to the limiting groove in the cathode seat through threaded engagement, and the cathode adjusting screw can rotate in the radial direction and stop in the axial direction relative to the limiting groove.

As a further improvement of the invention, the cold cathode comprises a substrate and a coating layer coated on the substrate, wherein the substrate is a metal or an alloy containing iron and nickel, and the coating layer is a carbon nano tube or graphene.

As a further improvement of the invention, the tail end of the cathode adjusting screw is provided with a limiting boss, a limiting groove is correspondingly arranged in the limiting groove, and the limiting boss is clamped in the limiting groove.

As a further improvement of the invention, at least two of the adjusting lugs are uniformly arranged on the periphery of the focusing pole bottom plate.

As a further improvement of the invention, a positioning groove is arranged on the bottom plate of the focusing electrode, and the top of the focusing electrode is penetrated in the positioning groove.

As a further improvement of the present invention, the anode part includes an anode and a target material provided on the anode.

The invention has the beneficial effects that:

1. according to the invention, different working voltages of the X-ray tube can be realized by adjusting the axial positions of the focusing electrode and the cathode, and X-rays with different short wave limits can be correspondingly obtained, so that the X-ray tube is suitable for different application occasions;

2. according to the invention, different electric field strengths on the surface of the cathode of the X-ray tube can be realized by adjusting the axial positions of the focusing electrode and the cathode, so that cathode currents with different sizes are correspondingly obtained, the intensity of the X-ray is further influenced, and the X-ray can be selected according to different application scenes;

3. due to various factors, the emission characteristics of the cold cathode are seriously inconsistent, the quality of emission current and X-rays meets the use requirement in the working voltage range by adjusting the axial positions of the focusing electrode and the cathode, the defect of poor consistency of the emission performance of the cathode can be made up to a greater extent, and the cold cathode ray tube is more suitable for batch production management;

4. the position of the cathode is kept unchanged, the focusing electrode is pushed to the grid by using the axial telescopic structure, when the position is proper, high voltage is added between the focusing electrode and the grid for purification treatment, the working reliability of the X-ray tube can be improved, meanwhile, due to the shielding effect of the focusing electrode, cathode current cannot be pulled out by the high voltage, and X rays cannot be generated naturally, so that no protective measures need to be taken in the whole purification process of the focusing electrode.

Drawings

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

FIG. 2 is a schematic cross-sectional view of the present invention;

FIG. 3 is a top view of FIG. 1;

FIG. 4 is an exploded view of a focusing electrode assembly according to the present invention;

FIG. 5 is a schematic view of an assembled state of a focusing electrode assembly according to the present invention;

fig. 6 is a schematic structural view of a cold cathode assembly according to the present invention.

The following description is made with reference to the accompanying drawings:

1 a-upper porcelain tube; 1 b-lower porcelain tube;

2-anode part; 3-grid electrode;

21-an anode; 22-target material;

4-cold cathode; 5-a focusing electrode;

6-cathode flange; 61-first adjustment threaded hole;

62-second threaded through hole; 7-locking nut;

8-focusing electrode base plate; 81-adjustment holes;

82-positioning groove; 9-adjusting lug;

91 — first via; 10-Focus pole adjustment screw;

11-outside bellows; 12-inside bellows;

13-cathode base; 14-central bellows;

15-cathode adjusting screw; 16-limiting groove.

Detailed Description

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to fig. 1-6, an adjustable cold cathode X-ray tube according to the present invention includes an upper ceramic tube 1a and a lower ceramic tube 1b, an anode member 2 is disposed at a lower end of the lower ceramic tube 1b, a grid 3 is disposed between the upper ceramic tube 1a and the lower ceramic tube 1b, a cold cathode 4 and a focusing electrode 5 are disposed in the upper ceramic tube 1a, and a distance between the cold cathode 4 and the focusing electrode 5 with respect to the grid 3 is independently adjustable, which will be described in detail below.

A cathode flange 6 is arranged at the top opening of the upper ceramic tube 1a, a focusing electrode bottom plate 8 is additionally arranged, the focusing electrode 5 is cylindrical and is arranged in the upper ceramic tube 1a, and the top of the focusing electrode 5 movably penetrates through the cathode flange 6 and is fixedly connected with the focusing electrode bottom plate 8; a plurality of adjusting lugs 9 extending outwards are arranged on the focusing electrode bottom plate 8, each adjusting lug 9 is provided with a first through hole 91, a focusing electrode adjusting screw 10 is arranged in the first through hole 91, a first adjusting threaded hole 61 is correspondingly arranged on the cathode flange 6, the threaded end of the focusing electrode adjusting screw 10 penetrates through the first through hole 91 of the adjusting lug 9 and then reaches the first adjusting threaded hole 61, meanwhile, a locking nut 7 is sleeved outside the threaded end of the focusing electrode adjusting screw 10 and the part between the adjusting lug 9 and the cathode flange 6, and the locking nut 7 is in threaded engagement with the focusing electrode adjusting screw 10; the focusing electrode 5 is provided with an outer corrugated pipe 11 and an inner corrugated pipe 12 outside the part between the cathode flange 6 and the focusing electrode base plate 8, and the upper end and the lower end of the outer corrugated pipe 11 and the upper end and the lower end of the inner corrugated pipe 12 are respectively fixed on the cathode flange 6 and the focusing electrode base plate 8. When the focusing electrode 5 needs to be adjusted, the locking nut 7 is firstly loosened, the focusing electrode adjusting screw 10 is rotated, when the focusing electrode adjusting screw 10 rotates, the lower end of the focusing electrode adjusting screw is screwed into or out of a first adjusting threaded hole 61 correspondingly formed in the cathode flange 6, and the outer corrugated pipe 11 and the inner corrugated pipe 12 which are positioned between the cathode flange 6 and the focusing electrode base plate 8 are simultaneously extruded or stretched, so that the focusing electrode 5 is lifted relative to the cathode flange 6 along with the rotation of the focusing electrode adjusting screw 10, after the focusing electrode 5 is adjusted to a required position, the focusing electrode adjusting screw 10 is loosened, the locking nut 7 is rotated to be tightly attached to the focusing electrode base plate 8, the focusing electrode adjusting screw 10 is locked, and the adjustment of the axial position of the focusing electrode 5 is completed.

The center of the focusing electrode bottom plate 8 is provided with an adjusting hole 81, so that the cold cathode can be conveniently adjusted. The cold cathode 4 is arranged on a cathode base 13, the cathode base 13 can be arranged in the bottom of the focusing electrode 5 in a vertically sliding manner, and the upper end of the cathode base 13 is fixedly connected with a cathode flange 6 through a central corrugated pipe 14; the center of negative pole flange is equipped with second screw thread through-hole 62, and the side center of going up of negative pole seat 13 is equipped with spacing groove 16, is equipped with negative pole adjusting screw 15 in addition and passes second screw thread through-hole 62 on the negative pole flange 6 to the spacing groove 16 on the negative pole seat 13 through the thread engagement, and negative pole adjusting screw 15 can be relative spacing groove 16 radial rotation and axial locking, and concrete structure can be: the tail end of the cathode adjusting screw 15 is provided with a limiting boss, a limiting groove is correspondingly arranged in the limiting groove 16, and the limiting boss is clamped in the limiting groove. When the cold cathode 4 needs to be adjusted, the cold cathode enters the focusing electrode base plate 8 through the adjusting hole 81 formed in the center of the focusing electrode base plate 8, the cathode adjusting screw 15 can be rotated manually or by means of a tool, when the cathode adjusting screw 15 rotates, the bottom of the cathode adjusting screw is connected with the limiting groove 16 through the limiting boss, namely, the cathode adjusting screw 15 can rotate radially and stop axially relative to the limiting groove 16, and meanwhile, because the upper end of the cathode adjusting screw 15 is meshed with the second threaded through hole 62 in the cathode flange 6 through threads, when the cathode adjusting screw 15 rotates, the cathode adjusting screw 15 drives the cathode seat 13 and the cold cathode 4 to lift relative to the cathode flange 6, and extrudes or stretches the central corrugated pipe, so that the adjustment of the axial position of the cold cathode 4 is realized.

The cold cathode 4 comprises a substrate and a coating layer coated on the substrate, wherein the base material of the substrate is metal or alloy containing iron and nickel, and the coating layer is a carbon nano tube or graphene; the number of the adjusting lugs 9 is at least two, and the adjusting lugs are uniformly arranged on the periphery of the focusing electrode base plate 8, three are taken as an example in the embodiment, and the specific number is not limited; a positioning groove 82 is arranged on the focusing electrode bottom plate 8, and the top of the focusing electrode 5 penetrates into the positioning groove; the anode part 2 includes an anode 21 and a target 22 disposed on the anode, and the target 22 may be selected from a tungsten target, a molybdenum target, and the like, but the invention is not particularly limited.

In the adjustable cold cathode X-ray tube, a focusing electrode is cylindrical, a cylinder body of the focusing electrode penetrates through a cathode flange, an inner corrugated pipe is surrounded on the inner side of the cylinder body of the focusing electrode, an outer corrugated pipe is surrounded on the outer side of the cylinder body of the focusing electrode, one ends of two corrugated pipes are connected to a focusing electrode base plate, the other ends of the two corrugated pipes are connected with the cathode flange base plate, the two corrugated pipes and the cylinder body of the focusing electrode are concentric, and a focusing electrode adjusting structure is formed. When the focusing electrode needs to be adjusted, the focusing electrode adjusting screw is rotated to drive the focusing electrode base plate and the cylinder body of the focusing electrode to move axially relative to the cathode flange, so that the two corrugated pipes between the focusing electrode base plate and the cathode flange, as well as between the inner side and the outer side of the focusing electrode base plate and the cathode flange are subjected to stroke, and the distance between the focusing electrode and the cold cathode (or the grid) is changed. After the position of the focusing pole is adjusted, the locking nut 7 is screwed down, so that the position of the cylinder body of the focusing pole can be fixed, and the adjustment of the focusing pole is completed.

The cold cathode is arranged on the cathode base, and two ends of the central corrugated pipe are respectively connected to the bottom of the cathode base and the top of the cathode flange to form a cathode adjusting structure. When the position of the cold cathode needs to be adjusted, the cold cathode passes through the adjusting hole 81, the length of the central corrugated pipe can be changed by adjusting the cathode adjusting screw, the cathode seat moves on the inner wall of the cylinder body of the focusing electrode, the cold cathode is close to or far away from the grid, and the change of the position of the cold cathode relative to the distance between the grid and the anode is realized.

When the adjustable cold cathode X-ray tube is used, negative and positive high voltages are applied to the cathode and anode terminals, the grid is grounded, and under different power-on conditions, different emission currents or different light spots can be obtained by changing the positions of the cold cathode and the focusing electrode in the adjustable part, so that an ideal radiation dose can be obtained, the problems of emission consistency of an electron source and the like can be improved, the working stability and yield of a product can be improved, and the product can meet the application under various conditions, as exemplified below.

It is known that the continuous X-ray spectrum has a wavelength limit in the short-wave direction, called the short-wave limit lambda₀Which is an X-ray generated by a photon depleting its energy at one collision. It is only related to tube voltage V, and is not affected by other factors, i.e. each tube voltage V corresponds to a certain short wave limit lambda_0。

The shorter the wavelength of the X-ray, the less the substance absorbs it, and the greater its penetrability, and it is common to perform X-ray fluoroscopy, photography and protection with different penetrability and different absorption degrees of the substance.

The invention can realize the work under various voltage conditions by adjusting the axial positions of the focusing electrode and the cathode, thereby obtaining X-rays with different short wave limits; similarly, by adjusting the axial positions of the focusing electrode and the cathode, anode currents with different magnitudes can be obtained under the same working voltage, so that X-rays with different intensities can be obtained. In the following, only three operation modes of an adjustable X-ray tube are described as an example.

In a first mode of operation:

cathode voltage Vc-35 KV, anode voltage Va-80 KV, current Ia-9.5 mA, lambda₀0.0108nm, focal spot<1mm×1mm；

In the second mode of operation, the first mode of operation,

cathode voltage Vc-51 KV, anode voltage Va-80 KV, current Ia-5.2 mA, lambda₀0.0095nm, focal spot<1mm×1mm；

In a third mode of operation of the device,

cathode voltage Vc-80 KV, anode voltage Va-80 KV, current Ia-23 mA, lambda₀0.0078nm, focal spot<1mm×1mm。

The three modes realize the spanning of the working voltage of the X-ray tube from 115kV to 160kV, correspondingly shorten the short wave limit from 0.0108nm to 0.0078nm, change the current from 5mA to 23mA, and simultaneously ensure that the applicable focal spot size (less than 1mm multiplied by 1mm) is obtained. All this is achieved by adjusting the axial position of the focusing electrode and the cathode. The adjusting range of the focusing electrode and the cathode is not less than 6 mm, and the adjusting range is within the adjustable range of the invention.

Therefore, the adjustable cold cathode X-ray tube, the cathode and the focusing electrode can be independently adjusted, can be widely applied to medical, security inspection, industrial and other industrial X-ray imaging equipment, and has the advantages of high voltage, low power consumption, quick response, small volume, high resolution, long service life, small radiation dose and the like.

In the previous description, numerous specific details were set forth in order to provide a thorough understanding of the present invention. The foregoing description is only a preferred embodiment of the invention, which can be embodied in many different forms than described herein, and therefore the invention is not limited to the specific embodiments disclosed above. And that those skilled in the art may, using the methods and techniques disclosed above, make numerous possible variations and modifications to the disclosed embodiments, or modify equivalents thereof, without departing from the scope of the claimed embodiments. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the scope of the technical solution of the present invention.