CN202332778U - Focusing-type cold cathode X-ray tube - Google Patents
Focusing-type cold cathode X-ray tube Download PDFInfo
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- CN202332778U CN202332778U CN201120482484XU CN201120482484U CN202332778U CN 202332778 U CN202332778 U CN 202332778U CN 201120482484X U CN201120482484X U CN 201120482484XU CN 201120482484 U CN201120482484 U CN 201120482484U CN 202332778 U CN202332778 U CN 202332778U
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Abstract
The utility model discloses a focusing-type cold cathode X-ray tube. The focusing-type cold cathode X-ray tube comprises a field emitting cold cathode, a filament gate composed of a closed filament, an anode, an X-ray tube casing and a ray outgoing window, wherein the field emitting cold cathode and the anode are respectively arranged on both inner ends of the X-ray tube casing, and are extracted out of the X-ray tube casing through a cathode extraction electrode and an anode extraction electrode, respectively; the filament gate is arranged between the field emitting cold cathode and the anode, and both sides of the filament gate are extracted out of the X-ray tube casing through the two extraction electrodes; the anode has a slope surface for generating X rays by virtue of electron bombardment; and the ray outgoing window is arranged on the side surface of the X-ray tube casing and is dead against the slope surface. Compared with the common field emitting cold cathode X-ray tube, the focusing-type cold cathode X-ray tube provided by the utility model can be used for effectively removing gas by carrying out electron bombardment on the anode so as to improve the vacuum degree in the X-ray tube, and can focus electron beams to improve the performance of the X-ray tube and prolong the service life of the X-ray tube.
Description
Technical field
The utility model relates to a kind of cold cathode X-ray tube, is specifically related to a kind of focus type cold cathode X-ray tube.
Background technology
Traditional X-ray tube adopts filament material such as tungsten filament as negative electrode, when filament energising heating back emitting electrons, and under the anode high voltage effect, electron bombard anode generation X ray.But traditional X-ray tube is because want the filament heating, and filament emission current is little simultaneously, and the application in high-end imaging device is restricted.In recent years field emission cold cathode because of its need not heating, response rapidly, characteristic such as emission is big, begun Preliminary Applications in X-ray tube equal vacuum device.Adopt the X-ray tube of little point of silicon and Field Emission of Diamond Thin Films array to be achieved in the laboratory.Adopt nano materials such as CNT, nano zine oxide also to begin to use, and will be the x-ray source of high-end imaging devices such as following CT as the X-ray tube of field emission cold-cathode.
X-ray tube is as the vacuum device of a big current emission; Vacuum degree in the device has higher requirement, and the height of vacuum degree has directly influenced the focal imaging quality of X-ray tube and the life-span of negative electrode, therefore in the exhaust process of making except that adopting baking or high frequency degasification; Also need power up and make its emitting electrons filament; On anode, apply certain voltage (far below the voltage in when work), make the electron bombard anode, antianode carries out electron bombardment degassing to material.Simultaneously owing at this moment be applied to voltage on the anode far below operating voltage, electron beam can defocus, and the area that acts on the anode of electronics is increased, and can make the anode degasification more abundant.After the pipe sealed-off, guarantee that X-ray tube anode bleed amount when high voltage operation is fewer, do not influence the life-span and the performance of X-ray tube.
And the X-ray tube of employing field emission cold-cathode, the cathode electronics emission need just have the electronics emission under the high voltage when the approaching work of anode, under this voltage; Anode has produced X ray; Can bring radiation effect to operating personnel, the while electronics defocuses also not enough, and electronic action is little at the area of anode; The anode degasification neither be very abundant, the bad performance and the life-span that directly can influence X-ray tube of atmosphere in the pipe.
Therefore how the device antianodes such as X-ray tube at field emission cold-cathode carry out degasification, need carry out special consideration.
Summary of the invention
Goal of the invention: the purpose of the utility model is the deficiency to prior art, and a kind of focus type cold cathode X-ray tube that the electron bombard anode removes airway dysfunction that has is provided.
Technical scheme: the described focus type cold cathode of the utility model X-ray tube, the filament grid, anode, X-ray tube shell and the ray outgoing window that comprise field emission cold-cathode, constitute by the filament of closure; Said field emission cold-cathode and said anode are separately positioned on the inner two ends of said X-ray tube shell, and are drawn out to the outside of said X-ray tube shell respectively through negative electrode extraction electrode and anode extraction electrode; Said filament grid is arranged between said field emission cold-cathode and the said anode, and its two sides are drawn out to the outside of said X-ray tube shell respectively through two extraction electrodes, and the filament grid that makes closed filament constitute becomes the filament of two parallel connections; Said anode has one and is used for the slope that electron bombard produces X ray, and said ray outgoing window is arranged on the side of said X-ray tube shell and faces said slope place.
The effect of filament grid has two: one in the utility model X-ray tube, in exhaust process; The voltage Vf that on two extraction electrodes of filament grid, applies the heat filament grid makes it add thermal electron to filament; On anode, applying a voltage Vah in order to the degasification of accelerated electron bombardment anode simultaneously; Electron bombard can make the anode heating emit gas on the one hand, can form the electronic induction desorption on the other hand and emit gas; Regulate the height of anode voltage Vah, can adjust electron beam at the area and the heating power that act on the anode; The 2nd, when X-ray tube is worked; Apply equipotential voltage Vg on two extraction electrodes of filament grid, the high pressure Va when anode adds operate as normal regulates being applied to the voltage on the filament grid; Can realize focusing, play the effect of focusing electrode field emission cold cathode electrons emitted bundle.
In the utility model; The effect of filament grid just adds thermal electron as filament in the tube-making process process; In normal operating conditions, as the focusing electrode and the anode acting in conjunction of field emission cold-cathode; Regulate cathode emission electron beam spot size, thus the spatial resolution of control outgoing X ray.
Comparative optimization ground, said filament grid be shaped as identical circular or square of shape with said field emission cold-cathode; Said filament grid is to be processed by the tungsten filament with thermionic emission function, rhenium tungsten filament, thoriatde-tungsten wire or the oxide coated cathode filament or calcium oxide, strontium oxide strontia and the barytic alkaline earth oxide filament that are coated with yittrium oxide, scandium oxide.
Said anode is to be processed by tungsten, molybdenum, oxygen-free copper or heavy metal material.
Said field emission cold-cathode is that nano material or diamond thin of having field emission performance by metal micro tips array such as tungsten, molybdenum or CNT, zinc oxide, aluminium nitride etc. etc. processed.
The method of utilizing the said focus type cold cathode of the utility model X-ray tube antianode to carry out degasification comprises the steps:
(1) on two extraction electrodes of filament grid, apply different potentials, utilize voltage difference Vf that filament is heated, the size of regulating Vf is to regulate the filament heating-up temperature to producing thermionic emission;
(2) on anode, apply simultaneously voltage Vah and (be generally 10V～10KV),, regulate anode voltage Vah and act on area and heating power on the anode to regulate electron beam in order to quicken the purpose that filament grid electrons emitted bombardment anode reaches the antianode degasification.
Utilize the described focus type cold cathode of the utility model X-ray tube to be: in the X-ray tube course of normal operation, to apply voltage Va at anode to field emission cold-cathode electrons emitted Shu Jinhang method of focusing; On two extraction electrodes of filament grid, apply identical current potential Vg, at this moment be applied to the voltage difference Vf=0 on the filament grid, filament is not heated; The size of regulating Vg realizes the focusing to field emission cold-cathode electrons emitted bundle to change the Electric Field Distribution between field emission cold-cathode and the anode.
What the utility model provided is the basic structure and the process program of cold cathode X-ray tube, to the improvement of concrete anode, cathode construction, and in pipe, increases other electrodes, does not influence the enforcement of this programme.
Beneficial effect: 1, the utility model is through increasing the filament grid of the two extraction electrodes of band between cold cathode and anode; In exhaust process; On two electrodes of filament grid, apply different voltages and make it add thermal electron, on anode, apply a voltage in order to the degasification of accelerated electron bombardment anode to filament; When X-ray tube is worked, apply equipotential voltage on two extraction electrodes of filament grid, regulate this voltage, can realize focusing to field emission cold cathode electrons emitted bundle, play the effect of focusing electrode.2, compare with the traditional hot cathode X ray tube, the utlity model has the advantage that cold cathode X-ray tubes such as response speed is fast, Miniaturizable are had; Compare with common field emission cold-cathode X-ray tube, the utility model effectively antianode carries out electron bombardment degassing, improves vacuum degree in the X-ray tube, can focus on electron beam simultaneously, promotes the performance and the life-span of X-ray tube.3, the utility model is widely used, and can also be applied in other cold cathode high anode voltage vacuum electron devices.
Description of drawings
Fig. 1 is the utility model structural representation.
Fig. 2 is the sketch map of annular filament grid.
Fig. 3 is the sketch map of the square front lamp wire grid utmost point.
Embodiment
Be elaborated in the face of the utility model technical scheme down, but the protection range of the utility model is not limited to said embodiment.
Embodiment: the said focus type cold cathode of the utility model X-ray tube, as shown in Figure 1, the filament grid 2, anode 4, X-ray tube shell 5 and the ray outgoing window 6 that comprise field emission cold-cathode 1, constitute by the filament of closure; Said field emission cold-cathode 1 is separately positioned on the two ends of said X-ray tube shell 5 inside with said anode 4, and is drawn out to the outside of said X-ray tube shell 5 respectively through negative electrode extraction electrode 7 and anode extraction electrode 8; Said filament grid 2 is arranged between said field emission cold-cathode 1 and the said anode 4, and through two extraction electrode 3-1,3-2 is drawn out to the outside of said X-ray tube shell 5 respectively in its two sides; Said filament grid 2 be shaped as identical circular or square of shape with said field emission cold-cathode 1, shown in Fig. 2 and 3; Said anode 4 has one and is used for the slope that electron bombard produces X ray, and said ray outgoing window 6 is arranged on the side of said X-ray tube shell 5 and faces said slope place.
After assembled such as field emission cold-cathode 1, filament grid 2, anode 4 and X-ray tube shell 5, X-ray tube is connected on the vacuum exhaust platform it is carried out exhaust.With baking oven body is toasted in the exhaust process, to help the discharge of various component materials adsorbed gases in the X-ray tube, after the baking exhaust finished, also available high frequency coil antianode carried out bake out.But, still can not absorption and dissolved gases in the anode material fully be got rid of with the method for bakeout degassing and high frequency degasification.At this moment, on grid extraction electrode 3-1 and 3-2, apply a filament voltage Vf, like 5V, under the filament voltage effect, the filament grid is as two filaments of parallel connection, and when temperature was enough high, as 700 ℃-1500 ℃, filament was with heat of emission electronics.On anode, apply voltage Vah; Like 1000V, at this moment the filament electrons emitted will be bombarded anode, and electron bombard can make the anode heating emit gas on the one hand; Can form the electronic induction desorption on the other hand and emit gas, anode absorption and dissolved gases are fully got rid of.With pipe sealed-off exhaust station, accomplish X-ray tube and make after exhaust is accomplished.
When the said focus type cold cathode of the utility model X-ray tube normally uses work, cathode electrode ground connection, anode connects the high pressure of tens thousand of volts, and as 30,000 volts, at this moment negative electrode will have electronics to be transmitted into anode, and the electron bombard anode produces X ray.Add after two extraction electrodes of filament grid are connected together and focus on voltage Vg; Or an electrode is unsettled, and an electrode adds focusing voltage Vg, and the big young pathbreaker of Vg influences the focusing situation of cathode emission electron beam; Through regulating Vg; Make electron beam be focused into little bundle spot,, improve X-ray tube and go out light quality like 0.5 mm dia.
The geomery of filament grid and position can be optimized according to the concrete structure of X-ray tube, generally are placed on the position near negative electrode.The making of negative electrode can be made the method making of the little points of metal such as tungsten, molybdenum through the method for vacuum evaporation on cathode substrate; Also can adopt method cold-cathode material such as nano material grown, diamond thin on cathode substrate of chemical vapour deposition (CVD), also can adopt the method for silk screen printing that the nanometer cold-cathode material is printed onto on the cathode substrate material and process.
As stated, although represented and explained the utility model that with reference to specific preferred embodiment it shall not be construed as the restriction to the utility model self.Under the spirit and scope prerequisite of the utility model that does not break away from the accompanying claims definition, can make various variations in form with on the details to it.
Claims (2)
1. focus type cold cathode X-ray tube is characterized in that: the filament grid (2), anode (4), X-ray tube shell (5) and the ray outgoing window (6) that comprise field emission cold-cathode (1), be made up of the filament of closure; Said field emission cold-cathode (1) and said anode (4) are separately positioned on the inner two ends of said X-ray tube shell (5), and are drawn out to the outside of said X-ray tube shell (5) respectively through negative electrode extraction electrode (7) and anode extraction electrode (8); Said filament grid (2) is arranged between said field emission cold-cathode (1) and the said anode (4), and (3-1 3-2) is drawn out to the outside of said X-ray tube shell (5) through two extraction electrodes respectively in its two sides; Said anode (4) has one and is used for the slope that electron bombard produces X ray, and said ray outgoing window (6) is arranged on the side of said X-ray tube shell (5) and faces said slope place.
2. according to the said focus type cold cathode of claim 1 X-ray tube, it is characterized in that: said filament grid (2) be shaped as identical circular or square of shape with said field emission cold-cathode (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120482484XU CN202332778U (en) | 2011-11-29 | 2011-11-29 | Focusing-type cold cathode X-ray tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120482484XU CN202332778U (en) | 2011-11-29 | 2011-11-29 | Focusing-type cold cathode X-ray tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202332778U true CN202332778U (en) | 2012-07-11 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201120482484XU Withdrawn - After Issue CN202332778U (en) | 2011-11-29 | 2011-11-29 | Focusing-type cold cathode X-ray tube |
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| CN (1) | CN202332778U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102427015A (en) * | 2011-11-29 | 2012-04-25 | 东南大学 | Focusing type cold cathode X-ray tube |
| CN103632903A (en) * | 2013-03-12 | 2014-03-12 | 东南大学 | Cold-cathode triode with electric field compensation |
| CN104319215A (en) * | 2014-11-05 | 2015-01-28 | 东南大学 | Cold cathode electron gun allowing circular plane cathode to correspond to circular-truncated-cone-shaped and column-shaped combination grid hole |
-
2011
- 2011-11-29 CN CN201120482484XU patent/CN202332778U/en not_active Withdrawn - After Issue
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102427015A (en) * | 2011-11-29 | 2012-04-25 | 东南大学 | Focusing type cold cathode X-ray tube |
| CN102427015B (en) * | 2011-11-29 | 2014-03-12 | 东南大学 | Focusing type cold cathode X-ray tube |
| CN103632903A (en) * | 2013-03-12 | 2014-03-12 | 东南大学 | Cold-cathode triode with electric field compensation |
| CN104319215A (en) * | 2014-11-05 | 2015-01-28 | 东南大学 | Cold cathode electron gun allowing circular plane cathode to correspond to circular-truncated-cone-shaped and column-shaped combination grid hole |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20120711 Effective date of abandoning: 20140312 |
|
| AV01 | Patent right actively abandoned |
Granted publication date: 20120711 Effective date of abandoning: 20140312 |