CN115903004A - MCP life test method and system for high-energy cosmic ray detection - Google Patents
MCP life test method and system for high-energy cosmic ray detection Download PDFInfo
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- CN115903004A CN115903004A CN202211544385.9A CN202211544385A CN115903004A CN 115903004 A CN115903004 A CN 115903004A CN 202211544385 A CN202211544385 A CN 202211544385A CN 115903004 A CN115903004 A CN 115903004A
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Abstract
The invention provides a method and a system for testing the service life of an MCP (micro-channel plate) for high-energy cosmic ray detection, which are used for solving the technical problem that the conventional method for evaluating the service life of the MCP by marking the output brightness gain change of an image intensifier easily generates system errors. The test method comprises the following steps: sequentially placing an electron cathode, an MCP sample to be detected and an anode plate in a high vacuum tube, and sequentially arranging an adjustable diaphragm and the high vacuum tube on an incident light path of a high-energy light source; closing the adjustable diaphragm, opening the high-energy light source and calibrating the high-energy light source; sequentially applying high-voltage electric fields to the anode plate, the MCP sample to be detected and the electron cathode; adjusting the position and the aperture size of the adjustable diaphragm; after electrons are subjected to electron multiplication and electron collection sequentially through an MCP sample to be detected and an anode plate, the anode plate outputs current; detecting the output current of the anode plate, and normalizing the laser intensity in the measurement interval by taking the maximum value of the laser intensity as a reference; and obtaining the service life of the MCP sample to be detected.
Description
Technical Field
The invention relates to high-energy cosmic ray detection, in particular to a method and a system for testing the service life of an MCP for high-energy cosmic ray detection.
Background
In the high-energy cosmic ray detection process, in order to realize the resolution of protons and ions with different energies, an image intensifier with a large dynamic range and a long service life is generally adopted as detection equipment. The microchannel plate (MCP for short) is a photomultiplier with a two-dimensional structure, has the characteristics of high gain, large dynamic range, low noise, high time resolution, high spatial resolution and the like, and can detect electrons, ions, ultraviolet photons, alpha particles, beta particles, gamma particles, neutrons, x rays and the like to obtain the characteristics of the electrons, the ions, the ultraviolet photons, the alpha particles, the beta particles, the gamma particles, the neutrons, the x rays and the like in time and space.
The successful development of the microchannel plate not only improves the gain of the image intensifier, but also reduces the volume and the weight of the image intensifier, and the microchannel plate is widely applied to the high-tech fields of universe exploration, earth observation, ocean monitoring and the like. However, the microchannel plate has more strict requirements on the operating environment, the manufacturing technology and the storage environment, and thus causes instability of the gain and a problem of the lifetime. In order to explore the engineering application of the microchannel plate in aerospace, various modes of the microchannel plate, namely an accurate MCP life change curve, which is related to the average life, gain failure and gain reduction rule, need to be obtained so as to judge and guide the correct time region for the use of the microchannel plate. The method is a destructive test in nature, but has strong practical guiding significance for researching and analyzing the change rule of the service life of the microchannel plate.
At present, the MCP life is mainly evaluated by marking the output brightness gain variation of the image intensifier, but because of many factors influencing the image intensifier gain, the image intensifier gain is not only related to the life and reliability of the MCP, and whether the MCP causes the MCP cannot be judged in the analysis process. Therefore, the test method is easy to generate system errors in the implementation process, and mainly comprises the following steps: the position error of light incidence to the cathode, the cosine error of the included angle of the optical axes of the equipment and the testing device, the measurement error of the brightness meter, the random error of the brightness meter and the like.
Disclosure of Invention
The invention aims to solve the technical problem that the conventional method for evaluating the service life of an MCP by marking the output brightness gain change of an image intensifier is easy to generate system errors, and provides a service life testing method and a system for the MCP for high-energy cosmic ray detection.
In order to solve the technical problems, the technical solution of the invention is as follows:
a method for testing the service life of an MCP for high-energy cosmic ray detection is characterized by comprising the following steps:
sequentially arranging an electronic cathode, an MCP sample to be detected and an anode plate in an integrally closed high vacuum tube, and arranging gaps between the MCP sample to be detected and the electronic cathode and between the MCP sample to be detected and the anode plate; the adjustable diaphragm and the high vacuum tube are sequentially arranged on an incident light path of the high-energy light source, so that the adjustable diaphragm is positioned at the front end of the electron cathode; the pulse width of the high-energy light source is 10-100ns, the power is more than 3W, and the electron energy bombarded to the electron cathode is 1eV-15eV;
2, closing the adjustable diaphragm, opening the high-energy light source, and calibrating the spectral line and the intensity of the high-energy light source to detect whether the spectral line and the intensity meet the requirements or not;
sequentially applying corresponding high-voltage electric fields to the anode plate, the MCP sample to be detected and the electron cathode respectively to enable the device to be in a working state;
4 regulating the position and aperture of the adjustable diaphragm according to the position and size of the MCP sample to be measured to make the output current density of the electron cathode under the action of the electric field 10 after receiving the photons -9 A/cm 2 An order of magnitude of electrons; the electrons are subjected to electron multiplication and electron collection sequentially through the MCP sample to be detected and the anode plateThen, the anode plate outputs current;
detecting the output current of the anode plate, and normalizing the laser intensity in the measuring interval by taking the maximum value of the laser intensity as a reference; obtaining the service life MCP of the MCP sample to be detected through the following formula life ：
Wherein Q is n Represents the total charge collected by the anode plate; s. the in Represents the area of the laser incident electron cathode; i represents the current instantaneously generated at the anode plate; q 0 Representing the total amount of charge of the anode plate in the initial state); f (I, t) represents a laser intensity normalization function; r denotes the current clear aperture of the adjustable diaphragm.
Further, step 1 specifically comprises:
placing the electron cathode, the MCP sample to be detected and the anode plate in a vacuum degree of 10 -4 Pa-10 -3 In a high vacuum tube with Pa magnitude, an MCP sample to be detected is arranged between an electron cathode and an anode plate; gaps between the MCP sample to be detected and the electron cathode and between the MCP sample to be detected and the anode plate are 1mm-3mm, and the gaps are supported by resin materials so as to prevent high-voltage discharge, high-voltage breakdown and high-temperature structural deformation under the vacuum condition.
Further, in step 3, sequentially applying corresponding high-voltage electric fields to the anode plate, the MCP sample to be measured, and the electron cathode, respectively, specifically:
applying 1000-1500V adjustable voltage on the anode plate;
the input surface of the MCP sample to be detected is grounded, if the MCP sample to be detected is single MCP, adjustable voltage of 0-1000V is applied to the output surface of the MCP sample to be detected, and if the MCP sample to be detected is double MCP, adjustable voltage of 1000-1800V is applied to the output surface of the MCP sample to be detected;
and applying a starting voltage of-170V to 250V to the electron cathode.
Further, steps 1-5 are performed in a dark room to prevent ambient light from affecting the test results.
In order to realize the method for testing the service life of the MCP for high-energy cosmic ray detection, the invention also provides a system for testing the service life of the MCP for high-energy cosmic ray detection, which is characterized in that:
the device comprises a laser, an adjustable diaphragm, an electronic cathode, an anode plate, a first ammeter, a driving wire, a first ammeter data acquisition card, a spectrometer, a control system and a coaxial cable;
a light homogenizing device and a high vacuum tube are sequentially arranged in the emergent light direction of the laser;
the electron cathode, the MCP sample to be detected and the anode plate are sequentially arranged in the high vacuum tube along the emitting direction of the laser, and gaps are formed between the MCP sample to be detected and the electron cathode and between the MCP sample to be detected and the anode plate;
the adjustable diaphragm is positioned between the light homogenizing device and the electron cathode, and the position and the aperture size of the adjustable diaphragm can be adjusted;
the input end of the first ammeter is connected with the output end of the anode plate through a coaxial cable and is used for detecting the output current of the anode plate; the output end of the first ammeter is connected with the input end of the first ammeter data acquisition card and used for acquiring detected current data, and the output end of the first ammeter data acquisition card is connected with the first input end of the control system and used for transmitting the acquired current data to the control system;
the spectrometer is provided with a collection optical fiber; the acquisition optical fiber is positioned at the rear end of the light homogenizing device and is used for acquiring the output laser intensity of the laser in real time; the spectrometer is used for monitoring the laser intensity in real time, and the output end of the spectrometer is connected with the second input end of the control system and is used for transmitting the laser intensity to the control system;
the control system is used for obtaining the service life of the MCP sample to be detected according to the input laser intensity of the laser, the output current of the anode plate and the current light transmission aperture of the adjustable diaphragm;
and one output end of the control system is connected with the input end of the adjustable diaphragm through a driving wire and is used for adjusting the position and the aperture size of the adjustable diaphragm.
Further, the clear aperture of the adjustable diaphragm is less than or equal to the diameter of the MCP sample to be detected;
the vacuum degree of the high vacuum tube is 10 -4 Pa-10 -3 Pa magnitude;
the resistance of the first ammeter is more than or equal to 10 12 Omega, current accuracy up to 1 x 10 -13 A；
The first ammeter is matched with the integral impedance formed by the electron cathode, the MCP sample to be detected and the anode plate;
the diameter of the optical fiber core of the collecting optical fiber is larger than 400um, and the passing wavelength of the collecting optical fiber is 190-1100nm;
the control system calculates the service life MCP of the MCP sample to be detected through the following formula life ：
Wherein Q n Represents the total charge collected by the anode plate; s in Represents the area of the laser incident electron cathode; i represents the current instantaneously generated at the anode plate; q 0 Represents the total charge of the anode plate in the initial state; f (I, t) represents a laser intensity normalization function; r denotes the current clear aperture of the adjustable diaphragm.
Furthermore, the gaps between the MCP sample to be detected and the electron cathode and between the MCP sample to be detected and the anode plate are 1mm-3mm;
the distance from the laser to the incident surface of the electron cathode is less than or equal to 20cm;
the length of the coaxial cable is less than or equal to 30cm;
the end face of the collecting optical fiber is positioned at a position 10cm-40cm behind the light homogenizing device, and the included angle between the fiber core axis of the collecting optical fiber and the normal of the light homogenizing device is 45-80 degrees.
Furthermore, the distance from the laser to the incident plane of the electron cathode is 3cm-5cm, so that the electron excitation effect is better improved;
the length of the coaxial cable is 10cm, so that the interference of the surrounding electromagnetic environment can be effectively reduced;
the end face of the collecting optical fiber is located 20cm behind the light homogenizing device, and the included angle between the fiber core axis of the collecting optical fiber and the normal of the light homogenizing device is 50 degrees.
Furthermore, resin supporting structures are arranged between the MCP sample to be detected and the electron cathode and between the MCP sample to be detected and the anode plate, and are used for preventing high-voltage discharge, high-voltage breakdown and high-temperature structural deformation under a vacuum condition.
Further, the device also comprises a second ammeter and a second ammeter data acquisition card;
the input end of the second ammeter is connected with the output end of the electronic cathode and used for detecting the output current of the electronic cathode, the output end of the second ammeter is connected with the input end of a second ammeter data acquisition card and used for acquiring the output current of the electronic cathode in real time, and the output end of the second ammeter data acquisition card is connected with the third input end of the control system.
Further, the clear aperture of the adjustable diaphragm is 2mm-10mm;
the vacuum degree of the high vacuum tube is 10 -4 Pa-10 -3 Pa magnitude;
gaps between the MCP sample to be detected and the electron cathode and between the MCP sample to be detected and the anode plate are 1mm-3mm;
the distance from the laser to the incident plane of the electronic cathode is less than or equal to 20cm;
the length of the coaxial cable is less than or equal to 30cm;
the end face of the collecting optical fiber is positioned at a position 10cm-40cm behind the light homogenizing device, and the included angle between the fiber core axis of the collecting optical fiber and the normal of the light homogenizing device is 45-80 degrees.
Further, the clear aperture of the adjustable diaphragm is 2mm-4mm;
the distance from the laser to the electron cathode incident plane is 3cm-5cm, so that the electron excitation effect is better improved;
the length of the coaxial cable is 10cm, so that the interference of the surrounding electromagnetic environment can be effectively reduced;
the end face of the collecting optical fiber is located 20cm behind the light homogenizing device, and the included angle between the fiber core axis of the collecting optical fiber and the normal of the light homogenizing device is 50 degrees.
Furthermore, resin supporting structures are arranged between the MCP sample to be detected and the electron cathode and between the MCP sample to be detected and the anode plate, and are used for preventing high-voltage discharge, high-voltage breakdown and high-temperature structural deformation under the vacuum condition.
Further, the device also comprises a second ammeter and a second ammeter data acquisition card;
the input end of the second ammeter is connected with the output end of the electronic cathode and is used for detecting the output current of the electronic cathode, the output end of the second ammeter is connected with the input end of a second ammeter data acquisition card and is used for acquiring the output current of the electronic cathode in real time, and the output end of the second ammeter data acquisition card is connected with the third input end of the control system;
the resistance of the second ammeter is more than or equal to 10 12 Omega, current accuracy up to 1 x 10 -13 A；
And the second ammeter is matched with the integral impedance formed by the electron cathode, the MCP sample to be detected and the anode plate.
The invention has the beneficial effects that:
1. the invention provides a method for testing the service life of an MCP for high-energy cosmic ray detection, which is characterized in that an electron cathode, a microchannel plate MCP and an anode plate are integrally arranged in a closed high vacuum tube, the position and the photon quantity of photons reaching the surface of the MCP cathode are controlled by adjusting the position and the aperture size of an adjustable diaphragm so as to realize the position and the intensity adjustment of the electron injection of the MCP, and then the service life of the MCP can be accurately obtained through the input laser intensity, the output current of the anode plate and the current light-transmitting aperture of the adjustable diaphragm.
2. The system for testing the service life of the MCP for high-energy cosmic ray detection provided by the invention is provided with the laser for generating incident photons, the position and the number of the photons incident on the surface of the electron cathode are adjusted by adjusting the position and the aperture size of the adjustable diaphragm, the adjustment of the position and the intensity of the electron injected into the MCP through the adjustable diaphragm is further realized, meanwhile, the real-time output laser intensity of the laser is detected in real time by using the spectrometer, the real-time output current of the anode plate is detected by using the first current meter, the system can accurately and effectively obtain the change process of the MCP output micro-current along with the irradiation time, and very important basis is provided for researching and analyzing the service life characteristics of the MCP.
3. According to the MCP life test system for high-energy cosmic ray detection, the second ammeter is connected to the output end of the electron cathode, whether the light source is stable or not can be reflected through detection of the output current of the electron cathode, and the performance of the electron cathode can be monitored in real time; meanwhile, the gain of the MCP can be obtained through the calculated ratio of the anode plate and the electron cathode.
Drawings
Fig. 1 is a schematic structural diagram of an MCP life testing system for high-energy cosmic ray detection according to the present invention.
The specific reference numbers are: (No. 10, 13 in the drawings)
1-a laser; 2-a light homogenization device; 3-an adjustable diaphragm; 4-an electron cathode; 5-MCP sample to be detected; 6-anode plate; 7-a first current meter; 8-a drive line; 9-a first galvanometer data acquisition card; 10-collecting optical fiber; 11-a drive power supply; 12-a spectrometer; 13-a control system; 14-coaxial cable.
Detailed Description
To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
A method for testing the service life of an MCP for high-energy cosmic ray detection specifically comprises the following steps:
1, placing an electron cathode 4, an MCP sample 5 to be detected and an anode plate 6 in an integrally closed vacuum degree of 10 -4 Pa-10 - 3 In a high vacuum tube with Pa magnitude, gaps of 1mm-3mm are arranged between an MCP sample 5 to be detected and the electron cathode 4 and between the MCP sample 5 to be detected and the anode plate 6; the gaps are supported by resin materials to prevent high-voltage discharge, high-voltage breakdown and high-temperature junction under vacuum conditionDeformation of the structure; arranging an adjustable diaphragm 3 and a high vacuum tube on an incident light path in sequence, and enabling the adjustable diaphragm 3 to be positioned at the front end of an electron cathode 4; wherein the pulse width of the high-energy light source is 10-100ns, the power is more than 3W, and the electron energy bombarded to the electron cathode 4 is 1eV-15eV;
2, closing the adjustable diaphragm 3, opening the high-energy light source, and calibrating the spectral line and the intensity of high-energy photons to detect whether the test requirements are met;
sequentially and respectively applying corresponding high-voltage electric fields to the anode plate 6, the MCP sample 5 to be detected and the electron cathode 4 to enable the device to be in an optimal working state; wherein, an adjustable voltage of 1000-1500V is applied on the anode plate 6; the input surface of the MCP sample 5 to be detected is grounded, if the MCP sample 5 to be detected is single MCP, adjustable voltage of 0-1000V is applied to the output surface of the MCP sample, and if the MCP sample 5 to be detected is double MCP, adjustable voltage of 1000-1800V is applied to the output surface of the MCP sample; a turn-on voltage of-170V to 250V is applied to the electron cathode 4. In the embodiment, the MCP sample 5 to be detected is single MCP, the input surface of the single MCP is grounded, the voltage applied by the output surface is positively correlated with the distance between the anode plate 6 and the MCP sample 5 to be detected, and the voltage applied by the output surface is 300V because the distance between the anode plate 6 and the MCP sample 5 to be detected is set to be 2mm in the embodiment; applying 1200V voltage to the anode plate 6; applying a starting voltage of-200V to the electron cathode 4; it is noted that when the test is finished, the electron cathode 4 should be protected by applying a turn-off voltage of 40-75V.
4, adjusting the position and the aperture of the adjustable diaphragm 3 according to the position and the size to be measured of the MCP sample 5 to be measured, so that the corresponding position on the surface of the electron cathode 4 receives as many photons as possible, and the electron cathode 4 excites the output current density to be 10 under the action of the electric field -9 A/cm 2 An order of magnitude of electrons; after the electrons are multiplied by the MCP sample 5 to be detected, the multiplied electrons are collected by the anode plate 6, and current is output;
detecting the output current of the anode plate 6, and normalizing the laser intensity in the measuring interval by taking the maximum value of the laser intensity as a reference; obtaining the service life MCP of the MCP sample 5 to be detected through the following formula life ：
Wherein Q n Represents the total amount of charge collected by the anode plate 6; the unit is C (coulomb); s in Represents the area of the laser-incident electron cathode 4; in units of cm (centimeters); i represents the current instantaneously generated at the anode plate 6; the unit is A (an), Q 0 Represents the total amount of charge of the anode plate 6 in the initial state condition, which is typically 0; the unit is C (coulomb); f (I, t) represents a laser intensity normalization function; r denotes the current clear aperture of the adjustable diaphragm 3 in cm (centimeters).
In order to prevent the influence of ambient light on the test result, the test of the invention needs to be carried out in a dark room.
In order to realize the method for testing the service life of the MCP for detecting the high-energy cosmic rays, the invention further provides a structure for testing the service life of the MCP for detecting the high-energy cosmic rays, which is shown in fig. 1 and comprises a high-vacuum tube, a laser 1, a light homogenizing device 2, an adjustable diaphragm 3, an electronic cathode 4, an anode plate 6, a first ammeter 7, a driving wire 8, a first ammeter data acquisition card 9, a driving power supply 11, a spectrometer 12, an acquisition optical fiber 10, a control system 13 and a coaxial cable 14.
The light source is provided by a laser 1, according to the characteristics and test requirements of the MCP sample 5 to be tested, an ultraviolet laser, specifically an ultraviolet LED, is adopted in the embodiment, the output center wavelength is less than or equal to 280nm, the wavelength drift is less than or equal to +/-3 nm at room temperature (25 ℃), the stable output power is more than or equal to 3.0W, and the service life is more than or equal to 2000 hours; in other embodiments of the present invention, the laser 1 may also use a light source such as an LD. The laser 1 is driven by the driving power source 11 to emit light in the present embodiment, and a signal source may be used to drive light emission when the laser 1 is low-powered. The light homogenizing device 2 and the high vacuum tube are sequentially positioned on the emergent light path of the laser 1. Wherein, the light homogenizing device 2 is used to uniformly distribute the incident laser energy, and it can usually adopt homogenizing devices such as ground glass, integrating sphere, etc. because the ground glass has small volume, simple structure and convenient operation, the preferred one in this embodiment isFrosted glass, and the frosted glass is closely attached to the laser 1, so that light spots with uniform energy can be obtained in an effective divergence angle. Vacuum degree of the high vacuum tube is 10 -4 Pa-10 -3 Pa magnitude, the electron cathode 4, the MCP sample 5 to be detected and the anode plate 6 are sequentially arranged in the high vacuum tube along the emitting direction of the laser 1, and gaps between the MCP sample 5 to be detected and the electron cathode 4 and between the MCP sample 5 to be detected and the anode plate 6 are set to be 1mm-3mm. In order to prevent high-voltage discharge, high-voltage breakdown and high-temperature structural deformation under a vacuum condition, resin support structures are arranged between the MCP sample to be detected 5 and the electron cathode 4 and between the MCP sample to be detected 5 and the anode plate 6. It is worth noting that in order to prevent ion pollution and air oxidation, when the system does not work, the high vacuum tube needs to be filled with nitrogen for storage, and when the system works next time, the high vacuum tube is set to be in a high vacuum state. The position and the aperture size of the adjustable diaphragm 3 can be adjusted, and the position and the number of photons incident on the surface of the electronic cathode 4 can be adjusted by adjusting the position and the aperture of the adjustable diaphragm 3, so that the corresponding position on the surface of the electronic cathode 4 can receive the number of photons as much as possible. The adjustable diaphragm 3 is positioned between the light homogenizing device 2 and the electron cathode 4, can be tightly attached to the outer surface of the high-vacuum tube light window, and also can be tightly attached to the front surface of the electron cathode 4, in the embodiment, the adjustable diaphragm 3 is tightly attached to the outer surface of the high-vacuum tube light window, and the arrangement is favorable for the structural design of the high-vacuum tube and the size adjustment of the adjustable diaphragm 3. The clear aperture of the adjustable diaphragm 3 can be set to different shapes, such as circle, square, triangle, star, etc., and in this embodiment, a circle is used; the clear aperture of the adjustable diaphragm 3 is less than or equal to the diameter of the MCP sample 5 to be tested, and the MCP sample 5 to be tested can be damaged due to performance degradation and damage of a partial area of the MCP sample 5 to be tested, so that the adjustable diaphragm 3 selects a tiny clear aperture as much as possible in the MCP life test process. An output end of the control system 13 is connected to an input end of the adjustable diaphragm 3 through a driving wire 8, and is used for driving and adjusting the position and the aperture size of the adjustable diaphragm 3 according to characteristics and test requirements. In order to select proper luminous flux in the test process, the adjustable diaphragm 3 in the embodiment adopts a pulse code modulation method to drive the rotary transmission shaft of the small servo motor to be adjustableThe aperture of stop 3 is brought to the appropriate angle. The electron cathode 4 is used for converting the incident photons into electrons through excitation, and can be generally prepared by using materials such as double alkali, multiple alkali, cs, au, cs, B and Gd, and the like, and since the light source in the embodiment is an ultraviolet light source, the electron cathode with gold-plated surface is adopted on the electron cathode 4, and the gold-plated thickness is 50 μm-200 μm. In order to obtain a better excitation effect, the distance between the laser 1 and the incident surface of the electron cathode 4 is not necessarily too long, and usually 20cm or less, preferably 3cm to 5cm, is required, and the smaller the distance between the two is, the larger the number of photons irradiated on the surface of the electron cathode 4 is, the larger the number of electrons excited by the electron cathode 4 is. The MCP sample 5 to be tested in the present invention is used to multiply the electrons inputted from the electron cathode 4, and a single MCP or a dual MCP may be used, in which the voltage applied to the output surface of the MCP sample 5 to be tested is twice that of the single MCP, and is usually 1000 to 1800V. In order to ensure that the MCP sample 5 to be measured can obtain sufficient electron injection, the current excited by the incident light on the surface of the electron cathode 4 in this embodiment needs to be greater than or equal to 5nA. The anode plate 6 is used for collecting electrons excited by the MCP sample 5 to be detected, the MCP sample can be made of a PCB or a graphite anode, and the like, and the MCP sample 5 is stored by filling nitrogen into a high vacuum chamber in the storage process. In order to collect all the electrons excited by the MCP sample 5 to be measured, the anode plate 6 generally keeps the same shape as the adjustable diaphragm 3, and the diameter of the anode plate 6 is larger than the maximum clear aperture of the adjustable diaphragm 3, that is, the diameter of the anode plate 6 is larger than the diameter of the MCP sample 5 to be measured.
The first ammeter 7 has a resistance of 10 or more 12 Omega, current accuracy up to 1 x 10 -13 And A, the input end of which is connected with the output end of the anode plate 6 through a coaxial cable 14 and is used for detecting the output current of the anode plate 6. The coaxial cable 14 is used as a main signal transmission channel to lead out a current signal from the anode plate 6, and in order to reduce the interference of the surrounding electromagnetic environment, the length of the coaxial cable 14 is less than or equal to 30cm, in this embodiment, 10cm. Meanwhile, in order to ensure the accuracy of the test result, it is noted that the impedance of the first ammeter 7 needs to be matched with the overall impedance formed by the electron cathode 4, the MCP sample 5 to be tested, and the anode plate 6, otherwise, the current output by the anode plate 6 is easily shunted, so that the MCP sample to be tested is shunted5 the life test results deviate from the true values. During the measurement, the signal cable of the first current meter 7 needs to be fixed to reduce the current jump phenomenon caused by vibration. The output end of the first ammeter 7 is connected with the input end of the first ammeter data acquisition card 9 and used for acquiring detected current data, and the output end of the first ammeter data acquisition card 9 is connected with the first input end of the control system 13 and used for transmitting the acquired current data to the control system 13. Preferably, the output end of the electronic cathode 4 is connected to a second current meter and a second current meter data acquisition card, the second current meter is used for detecting the output current of the electronic cathode 4, the requirements of the second current meter and the first current meter are the same, the output end of the second current meter is connected to the input end of the second current meter data acquisition card and is used for acquiring the output current of the electronic cathode 4 in real time, and the output end of the second current meter data acquisition card is connected to the third input end of the control system 13. Therefore, whether the light source is stable or not can be reflected by detecting the output current of the electronic cathode, and the performance of the electronic cathode 4 can be monitored in real time; meanwhile, the gain of the MCP can be obtained through the calculated ratio of the anode plate and the electron cathode.
During the test, the output power of the laser 1 will decrease continuously with time until a steady state is reached, and therefore the intensity of the output laser needs to be monitored. The collecting optical fiber 10 is positioned at the rear end of the light homogenizing device 2 and used for collecting the output laser intensity of the laser 1, the diameter of the optical fiber core of the collecting optical fiber 10 is larger than 400um, the passing wavelength of the collecting optical fiber is 190-1100nm, and a protective sleeve is arranged on the outer layer of the collecting optical fiber. The end face of the collecting optical fiber 10 is positioned at the position 10cm-40cm behind the light homogenizing device 2, and the included angle between the fiber core shaft and the normal of the light homogenizing device 2 is 45-80 degrees. Preferably, in this embodiment, an adjusting frame is disposed below the optical fiber light of the collecting optical fiber 10, and is used for adjusting the angle and position of the adjusting frame; the end face of the collecting optical fiber 10 is adjusted to be 20cm behind the ground glass, the included angle between the fiber core shaft and the normal of the ground glass is adjusted to be 50 degrees, and the output laser intensity of the collecting laser 1 can be better collected. The spectrometer 12 is used for monitoring the laser center wavelength and the laser intensity change in real time, and the output end of the spectrometer is connected with the second input end of the control system 13 through a USB for connecting the output end of the spectrometer with the second input end of the control system 13The laser intensity variation is transmitted to the control system 13. The control system 13 passes the service life MCP of the MCP sample 5 to be detected life Calculated by the following formula:
wherein Q is n Represents the total amount of charge collected by the anode plate 6; the unit is C (coulomb); s in Represents the area of the laser-incident electron cathode 4; in units of cm (centimeters); i represents the current instantaneously generated at the anode plate 6; the unit is A (an), Q 0 Represents the total amount of charge of the anode plate 6 in the initial state condition, which is typically 0; the unit is C (coulomb); f (I, t) represents a laser intensity normalization function; r denotes the current clear aperture of the adjustable diaphragm 3 in cm (centimeters).
The working principle of the system is as follows: the laser 1 generates incident photons, and the photons directly bombard the electron cathode 4 through the light homogenizing device 2 and the adjustable diaphragm 3 to excite electrons under the action of a proper electric field. The position and the aperture size of the diaphragm 3 are adjusted to control the position and the photon quantity of photons reaching the surface of the electron cathode 4, further realize the adjustment of the position and the intensity of electrons injected into the MCP sample 5 to be detected, and apply corresponding high voltage to the two ends of the MCP in the working process. In the testing process, on one hand, the real-time output laser intensity of the laser 1 within a period of time is detected in real time through the acquisition optical fiber 10 and the spectrometer 12, and is sent to the control system 13; on the other hand, the first current meter 7 detects the corresponding real-time output current of the anode plate 6 and sends the detected real-time output current to the control system 13. The control system 13 can accurately obtain the MCP service life after processing according to the input real-time output laser intensity, the real-time output current and the current clear aperture of the adjustable diaphragm 3. The test method and the test system can effectively reduce system errors and realize scientific and effective evaluation of the MCP service life. It provides detailed data support and technical instruction for the development of high-performance micro-light detecting device.
During the measurement, the isolation shielding of the first current meter 7 is necessary, and especially when the test voltage is relatively high and the current is small, the influence is great. In the measurement of micro-current, the fixture of the parts, the wire holder, the shielding wire and other isolation materials are carefully selected. From experience and actual data, it is known that materials such as polytetrafluoroethylene, glass, and ceramics have ideal insulating properties, but since glass and ceramics are difficult to process and easily damaged, polytetrafluoroethylene is preferred in this embodiment. The clamp, the joint and the like are kept clean in the using process, so that the isolation shielding performance of the first current meter 7 is kept good, and the measurement precision is improved. It is also important that the coaxial cable 14 be shielded, and shielded cables, preferably core coaxial shielded cables, must be used. The coaxial cable 14 is routed away from sources of interference, such as alternating current, high voltage power, etc.
The above description is only for the purpose of illustrating the technical solutions of the present invention and not for the purpose of limiting the same, and it will be apparent to those skilled in the art that modifications may be made to the specific technical solutions described in the above embodiments or equivalent substitutions for some technical features, and these modifications or substitutions may not make the essence of the corresponding technical solutions depart from the scope of the technical solutions protected by the present invention.
Claims (10)
1. A method for testing the service life of an MCP for high-energy cosmic ray detection is characterized by comprising the following steps:
the method comprises the following steps that 1, an electronic cathode (4), an MCP sample to be detected (5) and an anode plate (6) are sequentially arranged in an integrally closed high vacuum tube, and gaps are formed between the MCP sample to be detected (5) and the electronic cathode (4) and between the MCP sample to be detected (5) and the anode plate (6); an adjustable diaphragm (3) and a high vacuum tube are sequentially arranged on an incident light path of the high-energy light source; the pulse width of the high-energy light source is 10-100ns, the power is more than 3W, and the electron energy bombarded to the electron cathode (4) is 1eV-15eV;
2, closing the adjustable diaphragm (3), opening the high-energy light source, and calibrating the spectral line and the intensity of the high-energy light source;
sequentially and respectively applying corresponding high-voltage electric fields to the anode plate (6), the MCP sample (5) to be detected and the electron cathode (4) to enable the device to be in a working state;
according to waitingThe position and the aperture of the adjustable diaphragm (3) are adjusted by measuring the position and the size to be measured of the MCP sample (5), so that the electron cathode (4) outputs current density of 10 under the action of an electric field after receiving photons -9 A/cm 2 An order of magnitude of electrons; after electrons are subjected to electron multiplication and electron collection sequentially through an MCP sample (5) to be detected and the anode plate (6), the anode plate (6) outputs current;
detecting the output current of the anode plate (6), and normalizing the laser intensity in the measuring interval by taking the maximum value of the laser intensity as a reference; obtaining the service life MCP of the MCP sample (5) to be detected through the following formula life ：
Wherein Q is n Represents the total charge collected by the anode plate (6); s in Represents the area of the laser incident electron cathode (4); i represents the current instantaneously generated in the anode plate (6); q 0 Represents the total charge of the anode plate (6) in the initial state; f (I, t) represents a laser intensity normalization function; r represents the current clear aperture of the adjustable diaphragm (3).
2. The method of claim 1, wherein the method comprises:
the step 1 specifically comprises the following steps:
placing an electron cathode (4), an MCP sample (5) to be detected and an anode plate (6) in a vacuum degree of 10 -4 Pa-10 -3 In a high vacuum tube with Pa magnitude, an MCP sample (5) to be detected is placed between an electron cathode (4) and an anode plate (6); gaps between the MCP sample to be detected (5) and the electron cathode (4) and gaps between the MCP sample to be detected (5) and the anode plate (6) are 1mm-3mm, and the gaps are supported by resin materials.
3. The method for testing the life span of an MCP for high-energy cosmic ray detection according to claim 1 or 2, comprising:
in the step 3, sequentially applying corresponding high-voltage electric fields to the anode plate (6), the MCP sample to be detected (5) and the electron cathode (4) respectively comprises the following specific steps:
applying 1000-1500V adjustable voltage on the anode plate (6);
the input surface of the MCP sample (5) to be detected is grounded, if the MCP sample (5) to be detected is single MCP, adjustable voltage of 0-1000V is applied to the output surface of the MCP sample, and if the MCP sample (5) to be detected is double MCP, adjustable voltage of 1000-1800V is applied to the output surface of the MCP sample;
and applying a starting voltage of-170V to 250V on the electron cathode (4).
4. The method of claim 3 for testing life-span of an MCP for detecting high energy cosmic rays, comprising the steps of:
step 1 to step 5 were carried out in a dark room.
5. An MCP life test system for high-energy cosmic ray detection, which implements the MCP life test method for high-energy cosmic ray detection according to any one of claims 1 to 4, characterized by:
the device comprises a laser (1), an adjustable diaphragm (3), an electronic cathode (4), an anode plate (6), a first galvanometer (7), a driving line (8), a first galvanometer data acquisition card (9), a spectrometer (12), a control system (13) and a coaxial cable (14);
the light homogenizing device (2) and the high vacuum tube are sequentially arranged in the emergent light direction of the laser (1);
the electron cathode (4), the MCP sample to be detected (5) and the anode plate (6) are sequentially arranged in the high vacuum tube along the emergent direction of the laser (1), and gaps are formed between the MCP sample to be detected (5) and the electron cathode (4) and between the MCP sample to be detected (5) and the anode plate (6);
the adjustable diaphragm (3) is positioned between the light homogenizing device (2) and the electronic cathode (4), and the position and the aperture size of the adjustable diaphragm (3) can be adjusted;
the input end of the first ammeter (7) is connected with the output end of the anode plate (6) through a coaxial cable (14) and is used for detecting the output current of the anode plate (6); the output end of the first ammeter (7) is connected with the input end of a first ammeter data acquisition card (9) and used for acquiring detected current data, and the output end of the first ammeter data acquisition card (9) is connected with the first input end of the control system (13) and used for transmitting the acquired current data to the control system (13);
the spectrometer (12) is provided with a collection optical fiber (10); the acquisition optical fiber (10) is positioned at the rear end of the light homogenizing device (2) and is used for acquiring the output laser intensity of the laser (1) in real time; the spectrometer (12) is used for monitoring the laser intensity in real time, and the output end of the spectrometer is connected with the second input end of the control system (13) and is used for transmitting the laser intensity to the control system (13);
the control system (13) is used for obtaining the service life of the MCP sample (5) to be measured according to the input laser intensity of the laser (1), the output current of the anode plate (6) and the current light-transmitting aperture of the adjustable diaphragm (3);
and one output end of the control system (13) is connected with the input end of the adjustable diaphragm (3) through a driving wire (8) and is used for adjusting the position and the aperture size of the adjustable diaphragm (3).
6. The MCP life testing system for high-energy cosmic ray detection as claimed in claim 5, wherein:
the clear aperture of the adjustable diaphragm (3) is less than or equal to the diameter of the MCP sample (5) to be detected;
the vacuum degree of the high vacuum tube is 10 -4 Pa-10 -3 Pa magnitude;
the resistance of the first ammeter (7) is more than or equal to 10 12 Omega, current accuracy up to 1 x 10 -13 A；
The first galvanometer (7) is matched with the integral impedance formed by the electron cathode (4), the MCP sample to be detected (5) and the anode plate (6);
the diameter of the optical fiber core of the acquisition optical fiber (10) is larger than 400um, and the passing wavelength of the acquisition optical fiber is 190-1100nm;
calculating the service life MCP of the MCP sample (5) to be detected in the control system (13) by the following formula life ：
Wherein Q is n Represents the total charge collected by the anode plate (6); s. the in Represents the area of the laser incident electron cathode (4); i represents the current instantaneously generated in the anode plate (6); q 0 Represents the total charge of the anode plate (6) in the initial state; f (I, t) represents a laser intensity normalization function; r represents the current clear aperture of the adjustable diaphragm (3).
7. The MCP life testing system for high-energy cosmic ray detection as claimed in claim 6, wherein:
gaps between the MCP sample to be detected (5) and the electron cathode (4) and gaps between the MCP sample to be detected (5) and the anode plate (6) are 1mm-3mm;
the distance from the laser (1) to the incident surface of the electronic cathode (4) is less than or equal to 20cm;
the length of the coaxial cable (14) is less than or equal to 30cm;
the end face of the collecting optical fiber (10) is positioned at a position 10cm-40cm behind the light homogenizing device (2), and the included angle between the fiber core axis of the collecting optical fiber (10) and the normal of the light homogenizing device (2) is 45-80 degrees.
8. The MCP life testing system for high-energy cosmic ray detection as claimed in claim 7, wherein:
the distance from the laser (1) to the incident plane of the electronic cathode (4) is 3cm-5cm;
the length of the coaxial cable (14) is 10cm;
the end face of the collecting optical fiber (10) is located 20cm behind the light homogenizing device (2), and the included angle between the fiber core axis of the collecting optical fiber (10) and the normal of the light homogenizing device (2) is 50 degrees.
9. An MCP life test system for high energy cosmic ray detection according to any one of claims 5 to 8 where:
resin supporting structures are arranged between the MCP sample to be detected (5) and the electron cathode (4) and between the MCP sample to be detected (5) and the anode plate (6).
10. The MCP life testing system for high-energy cosmic ray detection as claimed in claim 9, wherein:
the device also comprises a second ammeter and a second ammeter data acquisition card;
the input end of the second ammeter is connected with the output end of the electronic cathode (4) and is used for detecting the output current of the electronic cathode (4), the output end of the second ammeter is connected with the input end of a second ammeter data acquisition card and is used for acquiring the output current of the electronic cathode (4) in real time, and the output end of the second ammeter data acquisition card is connected with the third input end of the control system (13);
the resistance of the second ammeter is greater than or equal to 10 12 Omega, current accuracy up to 1 x 10 -13 A；
And the second ammeter is matched with the integral impedance formed by the electron cathode (4), the MCP sample to be detected (5) and the anode plate (6).
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| CN202211544385.9A CN115903004A (en) | 2022-12-04 | 2022-12-04 | MCP life test method and system for high-energy cosmic ray detection |
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