CN110571114B - Gas X-ray image intensifier - Google Patents
Gas X-ray image intensifier Download PDFInfo
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- CN110571114B CN110571114B CN201910834794.4A CN201910834794A CN110571114B CN 110571114 B CN110571114 B CN 110571114B CN 201910834794 A CN201910834794 A CN 201910834794A CN 110571114 B CN110571114 B CN 110571114B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J31/00—Cathode ray tubes; Electron beam tubes
- H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
- H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output
- H01J31/506—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect
- H01J31/507—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output tubes using secondary emission effect using a large number of channels, e.g. microchannel plates
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Abstract
A gaseous X-ray image intensifier comprising: a readout anode plate (1); the micro-grid electrode structure (2) is formed by cascading n layers of micro-grid electrodes (21) through supporting structures (3), the supporting structures (3) are fixed on the readout anode plate (1), wherein the supporting structures (3) are positioned at two ends of the micro-grid electrode structure (2), gas avalanche amplification regions are formed between the micro-grid electrodes (21) and the readout anode plate (1), and n is an integer greater than or equal to 2; the entrance window (4) is formed above the micro-grid electrode structure (2), is connected with the readout anode plate (1) through the shell (6), and seals the micro-grid electrode structure (2) and the supporting structure (3); a drift cathode (5) formed on the inner surface of the entrance window (4); wherein the interior of the sealing structure is filled with a working gas for electron drift and avalanche multiplication. The device has high amplification factor of light intensity and conversion efficiency of X-ray, and has simple structure.
Description
Technical Field
The invention relates to the technical field of microstructure gas detectors and X-ray imaging, in particular to a gas X-ray image intensifier.
Background
X-ray image intensifiers (XRII) are important components of X-ray based imaging devices that convert X-rays to visible light, increasing their intensity by a factor of several times, much higher than conversion using a phosphor screen alone. XRII typically contains a low absorption and scattering input window (typically aluminum or beryllium), a fluorescent crystal for X-ray conversion, a photocathode, an electron focusing structure, and an output phosphor screen and output window. XRII of this field focusing type structure causes image distortion due to the presence of the focusing electric field. To solve this problem, the microchannel plate (MCP) technology is developed. However, limited by the existing MCP process technology, MCPs are still small in size and relatively expensive. In addition, in the MCP electron avalanche process, multiplied electrons can ionize trace residual gas in the vacuum tube to generate positive ions, and the positive ions flow back under the action of an electric field to damage the photocathode and reduce the service life of the photocathode. In addition, the XRII overall construction is not effectively simplified, as the use of a phosphor screen is still unavoidable.
To overcome the above problems, the skilled person proposes a gas X-ray image intensifier (gxrli). The existing GXRII adopts a hole type gas electron multiplier (GEM or THGEM) cascade or a single-layer Micromegas detector as an electron multiplication and luminescence structure. Although the total light intensity amplification of the device is high, the generated fluorescence is not directional, so that the effective light intensity that can reach the back-end image acquisition module is still limited. In the GEM cascade scheme, the electroluminescent light collection plane is arranged on the lower surface of the last GEM layer, only holes are formed to generate fluorescence, other areas form an imaging background image and cannot be removed, and similarly, the position of the micro-grid support structure of the Micromegas cannot generate fluorescence, so that a dead zone is formed in an output image. In addition, the X-ray conversion efficiency of the gas environment is lower than that of the solid fluorescent crystal, and the method for increasing the thickness and pressure of the converted gas has limited improvement on the problem
Disclosure of Invention
Technical problem to be solved
In view of the above technical problem, the present invention provides a gas X-ray image intensifier, which is used for at least partially solving the above technical problem.
(II) technical scheme
The invention provides an X-ray image intensifier, comprising: reading the anode plate 1; the micro-grid electrode structure 2 is formed by cascading n layers of micro-grid electrodes 21 through supporting structures 3, the supporting structures 3 are fixed on the readout anode plate 1, the supporting structures 3 are located at two ends of the micro-grid electrode structure 2, gas avalanche amplification regions are formed among the micro-grid electrodes 21 and between the micro-grid electrodes 21 and the readout anode plate 1, and n is an integer greater than or equal to 2; an entrance window 4 formed above the microelectrode structure 2, connected to the readout anode plate 1 through a housing 6, and sealing the microelectrode structure 2 and the support structure 3; a drift cathode 5 formed on an inner surface of the entrance window 4; wherein the sealing structure is filled with working gas for electron drift and avalanche multiplication.
Optionally, a tension greater than 25N/cm is applied to the surface of the microelectrode 21.
Optionally, the working gas is a mixed gas of an inert gas and an electronegative gas.
Optionally, the optical transmittance of the micro-grid electrode 21 is 30% to 60%.
Optionally, the thickness of the micro-grid electrode 21 is 10-40 microns, and the pitch of the avalanche amplification regions is 50-500 microns.
Optionally, the micropores of the upper layer of micro-grid electrodes 21 are misaligned with the micropores of the lower layer of micro-grid electrodes 21.
Optionally, the spacing of the gas avalanche amplification regions far away from the readout anode plate 1 is larger than the spacing of the gas avalanche amplification regions near the readout anode plate 1; wherein, the distance between the micro-grid electrode 21 and the readout anode plate 1 to form a gas avalanche amplification region is 50-150 microns; the spacing of the other gas avalanche amplification regions is 300- & lt500 & gt microns.
Alternatively, the material of the entrance window 4 is a thin film material for passing X-rays.
Alternatively, the readout anode plate 1 is made of light-transmitting glass on which a conductive film is formed.
Optionally, the working gas is a mixed gas of at least one of argon, xenon, and krypton and at least one of carbon tetrafluoride and methane.
(III) advantageous effects
The invention provides a gas X-ray image intensifier, which has the following beneficial effects:
1. a gas electron multiplier formed by cascading a plurality of layers of micro-grid electrodes is used as a GXRII amplification structure, so that the amplification factor of light intensity is improved.
2. Tension is applied to the microgrid electrode, and the microgrid electrode is fixed only through supporting structures at two ends, so that an imaging non-sensitive area caused by a traditional XRII or GXRII structure is eliminated.
3. The incident window material adopts an aluminum or beryllium film which is easy to pass by X-rays, gas is filled to replace the vacuum working environment of the traditional device, and the incident window material is used as an X-ray conversion medium, so that a crystal and a photoelectric cathode do not need to be converted, and the damage of ion feedback of the traditional device to the photoelectric cathode is eliminated.
4. The GXRII has simple structure (without need of photocathode, fluorescent screen, etc.), and is easy to be made into large area and low in cost.
Drawings
FIG. 1 is a schematic diagram showing a structure of a gas X-ray image intensifier according to an embodiment of the present invention.
Fig. 2 schematically shows a structure diagram of a gas X-ray image intensifier with three layers of micro-grid electrode cascades provided by the embodiment of the invention.
The same structure adopts the same reference numeral
1-reading anode plate
11-anode
2-microgrids electrode structure
21-microgrid electrode
3-support structure
4-entrance window
5-drift cathode
6-outer cover
G-working gas
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.
The embodiment of the invention provides a gas X-ray image intensifier, which comprises: reading the anode plate 1; the micro-grid electrode structure 2 is formed by cascading n layers of micro-grid electrodes 21 through a support structure 3, the support structure 3 is fixed on the reading anode plate 1, gas avalanche amplification regions are formed among the micro-grid electrodes 21 and between the micro-grid electrodes 21 and the reading anode plate 1, and n is an integer greater than or equal to 2; the incident window 4 is formed above the micro-grid electrode structure 2, is connected with the readout anode plate 1 through the shell 6, and seals the micro-grid electrode structure 2 and the supporting structure 3; a drift cathode 5 formed on an inner surface of the entrance window 4; the interior of the sealing structure is filled with a working gas for electron drift and avalanche multiplication.
FIG. 1 is a schematic diagram showing a structure of a gas X-ray image intensifier according to an embodiment of the present invention. As shown in fig. 1, the gas X-ray image intensifier (gxrli) includes:
the reading anode plate 1, the reading anode plate 1 can be made of a light-transmitting glass plate, and a conductive film can be made on the surface of the reading anode plate 1 to be used as an anode 11 of the reading anode plate 1.
The microgrid electrode structure 2 is formed by cascading n layers of microgrid electrodes 21 through supporting structures 3, the supporting structures 3 are fixed on the reading anode plate 1, wherein gas avalanche amplification areas are formed between the microgrid electrodes 21 and the reading anode plate 1, the supporting structures 3 are located at two ends of the n layers of microgrid electrodes 21, and n is an integer greater than or equal to 3.
Each micro-grid electrode 21 may have a thickness of 10-40 microns and an optical transmittance (or windowing) of between 30% and 60%. The high-tension microgrid is fixedly stretched by using a ceramic material (a support structure 3) with high hardness and low gas release (lower than a preset value required actually), and the tension of the microgrid electrodes is kept above 25N/cm, so that the support structure between the microgrid electrodes in a sensitive area of the device can be omitted. The distance between the microgrid electrodes 21 forming the avalanche amplification region can be 50-500 micrometers. To ensure a higher gain, the spacing of the avalanche amplification regions away from the readout anode plate 1 is typically larger than the spacing of the avalanche amplification regions close to the readout anode plate 1.
In an embodiment of the invention, the micro-grid electrode structure 2 is formed by cascading three layers of micro-grid electrodes 21, as shown in fig. 2, the width of the upper layer gas avalanche amplification region and the middle layer gas avalanche amplification region is wider and is 300-500 microns, and the width of the lower layer gas avalanche amplification region is narrower and is 50-150 microns.
The micropores of the upper layer of the microgrid electrodes 21 and the micropores of the lower layer of the microgrid electrodes 21 can be staggered, and the micropore staggering mode of the microgrid electrodes 21 can be realized by relatively selecting a certain angle for adjacent microgrids or adopting two modes of microgrids with different specifications.
And the incident window 4 is formed above the micro-grid electrode structure 2 and is connected with the reading anode plate 1 through the shell 6, so that the micro-grid electrode structure 2 and the supporting structure 3 are sealed in a vacuum manner. The material of the entrance window 4 is aluminum or beryllium film which is easy to pass through by X-ray. The housing 6 may be made of a material with a gas-tight sealing type and low gas release (lower than a preset value required actually), generally a metal and a ceramic material, and is sealed and packaged with the entrance window into a whole to realize working gas sealing.
And a drift cathode 5 formed on an inner surface of the entrance window 4. The drift cathode 5 material may be the same as the entrance window 4.
The sealing structure is filled with working gas G for electron drift and avalanche multiplication, and the working gas can be used as an X-ray conversion medium without conversion crystal. The working gas G may be, for example, a mixed gas of an inert gas (argon, neon, xenon, etc.) and an electronegative gas (carbon tetrafluoride, methane, etc.).
When the GXRII is used for image acquisition, a CCD camera or an optical camera is focused on the plane of the conducting film of the transparent glass for photographing and imaging, and the electroluminescence can be focused through the lens for imaging.
According to the gas X-ray image intensifier provided by the embodiment of the invention, the gas electron multiplier formed by cascading a plurality of layers of micro-grid electrodes is used as a GXRII amplification structure to form a multi-stage amplification area, so that the amplification factor of light intensity is improved. Tension (more than 25N/cm) is applied to the micro-grid electrode, and the micro-grid electrode is fixed only through the supporting structures at two ends, so that an imaging non-sensitive area caused by a traditional XRII or GXRII structure is removed, the sensitive area is enlarged, and the conversion efficiency of the GXRII to X rays is greatly improved. The incident window material adopts an aluminum or beryllium film which is easy to pass by X-rays, gas is filled to replace the vacuum working environment of the traditional device, and the incident window material is used as an X-ray conversion medium, so that a crystal and a photoelectric cathode do not need to be converted, and the damage of ion feedback of the traditional device to the photoelectric cathode is eliminated. And the GXRII device works in a gas sealing mode without gas circulation.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A gaseous X-ray image intensifier comprising:
a readout anode plate (1);
the micro-grid electrode structure (2) is formed by cascading n layers of micro-grid electrodes (21) through supporting structures (3), the supporting structures (3) are fixed on the readout anode plate (1), the supporting structures (3) are located at two ends of the micro-grid electrode structure (2), micropores of an upper layer of micro-grid electrodes (21) are staggered with micropores of a lower layer of micro-grid electrodes (21), gas avalanche amplification regions are formed between the micro-grid electrodes (21) and the readout anode plate (1), n is an integer larger than or equal to 2, and the optical transmittance of the micro-grid electrodes (21) is 30% -60%;
the thickness of the micro-grid electrode (21) is 10-40 microns, and the distance between the avalanche amplification regions is 50-500 microns;
wherein the spacing of the gas avalanche amplification regions far away from the readout anode plate (1) is larger than the spacing of the gas avalanche amplification regions near the readout anode plate (1);
the entrance window (4) is formed above the micro-grid electrode structure (2), is connected with the readout anode plate (1) through a shell (6) to form a sealing structure, and seals the micro-grid electrode structure (2) and the support structure (3);
a drift cathode (5) formed on an inner surface of the entrance window (4);
wherein the sealing structure is internally filled with a working gas for electron drift and avalanche multiplication.
2. The gaseous X-ray image intensifier as recited in claim 1, wherein a tension greater than 25N/cm is applied to the surface of said microelectrode (21).
3. The gaseous X-ray image intensifier as recited in claim 1, wherein said working gas is a mixture of an inert gas and an electronegative gas.
4. The gaseous X-ray image intensifier as recited in claim 1, wherein the distance between said microelectrode (21) and said readout anode plate (1) forming a gaseous avalanche amplification zone is 50-150 μm; the spacing of the other gas avalanche amplification regions is 300- & lt500 & gt microns.
5. A gaseous X-ray image intensifier as claimed in claim 1, the material of said entrance window (4) being a thin film material through which X-rays pass.
6. The gaseous X-ray image intensifier as recited in claim 1, wherein said reading anode plate (1) is made of light-transparent glass on which a conductive film is formed.
7. A gaseous X-ray image intensifier as claimed in claim 3, wherein said working gas is a mixture of at least one of argon, xenon and krypton with at least one of carbon tetrafluoride and methane.
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| CN201910834794.4A CN110571114B (en) | 2019-09-04 | 2019-09-04 | Gas X-ray image intensifier |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5192861A (en) * | 1990-04-01 | 1993-03-09 | Yeda Research & Development Co. Ltd. | X-ray imaging detector with a gaseous electron multiplier |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100550268C (en) * | 2007-04-17 | 2009-10-14 | 中国科学院西安光学精密机械研究所 | High resolution x-ray image intensifier |
| GB0804654D0 (en) * | 2008-03-13 | 2008-04-16 | Smith & Nephew | Vacuum closure device |
| CN109444224A (en) * | 2018-11-09 | 2019-03-08 | 中国科学技术大学 | A kind of micro-structure gas detector and preparation method thereof |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5192861A (en) * | 1990-04-01 | 1993-03-09 | Yeda Research & Development Co. Ltd. | X-ray imaging detector with a gaseous electron multiplier |
Non-Patent Citations (2)
| Title |
|---|
| CONSTRUCTION, TEST AND COMMISSIONING OF THE TRIPLE-GEM TRACKING DETECTOR FOR COMPASS;C. Altunbas et al;《Nuclear Instruments and Methods in Physics Research (Sect. A)》;20020121;第1-26页，图3-6 * |
| Ion backflow in thick GEM-based detectors of single photons;M. Alexeev et al;《PUBLISHED BY IOP PUBLISHING FOR SISSA MEDIALAB》;20130129;第1-17页，图2,6 * |
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