Method and device for measuring charged quantity of particles in plasma

Abstract

The invention relates to the technical field of detection of particles with points, in particular to a method and device for measuring the electric quantity of particles in plasma, and the device specifically comprises a structure design of a Faraday cup device with a storage bin and a controllable particle falling device. The problem that it is difficult to measure the electric quantity of a single large particle in a traditional measurement mode is solved. The Faraday cup device with the storage bin comprises a metal charge collector, a collector base, a base storage bin, a shielding shell, a shielding cover, a drift tube, an insulating base, an insulating top cover, a magnet and a magnet fixing device. A controllable particle falling device comprises a rear main body, a right main body, a left main body, push-pull type electromagnets and screws. The invention provides a method and a device for measuring the electrified quantity of particles in plasma, and solves the problems that the capacity of a Faraday cup collector is relatively small, the electrified quantity of multiple particles cannot be measured, and a signal cannot be distinguished when a large number of particles enter a Faraday cup at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of charged particle detection, and in particular to a method and device for measuring the charge of particles in plasma. Background Art

[0002] Plasma environments are extremely common in the aerospace field. Common plasma environments include but are not limited to the Earth's ionosphere, solar wind, thruster plumes, etc. In various ground-based experimental systems, various plasma environments are created to simulate the cosmic environment, or a large amount of plasma is generated in the experimental environment when conducting thruster experiments. Objects in a plasma environment will be charged by the influence of the plasma, and the charging of these objects may have a variety of effects. Equipment and instruments in a plasma environment can eliminate the influence of charge enrichment by grounding, etc., but small particles moving in a plasma environment, such as debris in the Earth's orbit, dust and micrometeorites widely present in space, are easy to be charged for a long time, which in turn brings greater harm to the objects they contact or collide with. Therefore, it is very necessary to measure the charging of various particles in a plasma environment.

[0003] The Faraday cup device is usually used to measure the plasma beam current and is a common and universal plasma diagnostic method. The Faraday cup can be used in many analytical instruments that need to detect ions or electrons, such as mass spectrometers. The Faraday cup is not as sensitive as other charged particle detectors such as electron multipliers and microchannel plates. However, the Faraday cup can obtain accurate charge quantity through the conversion of current and charge. They are often used in combination, with the Faraday cup used to detect stronger signals and the electron multiplier or microchannel plate used to detect tiny signals. In addition, the Faraday cup is also designed in the form of a retarding field analyzer (RFA), which can be used to measure the intensity and energy distribution of ion beams. However, due to the larger size of the particles and the discontinuous flow, the traditional Faraday cup device cannot effectively measure the charge of the particles. In addition, the existing device is not easy to control the particles to enter the Faraday cup one by one, making it difficult to measure the charge of a single particle, and then it is difficult to analyze the relationship between the charge of the particle and the parameters of the plasma environment in which it is located and its own particle size and shape. At the same time, compared with a continuous and large ion beam, the charge of a single particle is smaller, and the traditional Faraday cup signal processing method cannot measure such a small charge. Summary of the invention

[0004] In order to solve the above problems, an embodiment of the present invention provides a method and device for measuring the charge of particles in plasma, which specifically includes a Faraday cup device structure design with a storage bin and a controllable particle dropping device to solve the problem that traditional measurement methods are difficult to measure the charge of a single larger particle.

[0005] The technical solution of the present invention is as follows:

[0006] A Faraday cup device with a storage bin, comprising: a metal charge collector, a collector base, a base storage bin, a shielding shell, a shielding cover, a drift tube, an insulating base, an insulating top cover, a magnet, and a magnet fixing device;

[0007] The metal charge collector is placed in the collector base and is positioned by a positioner and a positioning hole. The collector base is coaxially placed on the base storage bin and is bonded and fixed to the base storage bin. The collector base and the base storage bin are placed inside a shielding shell and a shielding cover. The shielding shell and the shielding cover constitute a complete shielding layer. A through hole with a diameter 2-3 times that of the measured particle (e.g., a particle with a diameter of 2mm has a groove diameter of 4-6mm) is opened in the center of the shielding cover so that the particle can pass through. The shielding layer is placed inside an insulating base and an insulating top cover. The insulating base and the insulating top cover constitute a complete insulating layer. A through hole with a diameter 2-3 times that of the measured particle (e.g., a particle with a diameter of 2mm has a groove diameter of 4-6mm) is opened in the center of the insulating top cover so that the particle can pass through. The drift tube is coaxially placed in the through hole in the center of the insulating top cover. The magnet is fixed in a magnet fixing device. The magnet fixing device is fixed around the insulating top cover to generate a magnetic field to shield the plasma.

[0008] Furthermore, the metal charge collector can be made of copper, brass, silver and other conductive and non-magnetic metals, with a through hole at the lowest point having a diameter 2-3 times that of the measured particle (e.g., for a particle with a diameter of 2 mm, the slot diameter is 4-6 mm) for the particle to pass through, and a slot at the bottom for welding the wire;

[0009] Furthermore, the shielding shell, shielding cover and drift tube may be made of conductive and non-magnetic metals such as copper, brass, and silver;

[0010] Furthermore, the collector base, base storage bin, insulating base, and insulating top cover may be made of insulating materials with certain strength and high temperature resistance, such as epoxy resin and polycarbonate;

[0011] Furthermore, the magnet fixing device may be a conductive and non-magnetic metal such as copper, brass, silver, or an insulating material with a certain strength and high temperature resistance such as epoxy resin and polycarbonate;

[0012] Furthermore, the magnet may be a permanent magnet of various materials such as a neodymium iron boron magnet, an aluminum nickel cobalt magnet, or an electromagnet with a suitable number of turns;

[0013] A controllable particle dropping device, comprising a main body rear, a main body right, a main body left, a push-pull electromagnet, and a screw;

[0014] The middle of the rear of the main body is opened as a fixing point for the screws. The right side of the main body is fixed to the rear side of the main body with screws. The right surface of the main body is grooved, and the depth and width of the groove are adapted to the size of the particles passing through. For example, if the particle has a diameter of 2mm, the groove diameter is 2.4mm. The left side of the main body is a polycarbonate transparent plate, which is fixed to the right side of the main body with screws. The push-pull electromagnet has a rated voltage of 12V and is fixed on the rear side of the main body. The screws are fixed to the front end of the push-pull electromagnet and a vertical small hole is opened at the front end for particles to pass through.

[0015] Furthermore, the right and rear parts of the main body can be made of any material with certain strength and high temperature resistance;

[0016] Furthermore, the main body can be made of any transparent material with a certain strength and high temperature resistance;

[0017] Furthermore, the rated voltage of the push-pull magnet can be arbitrarily selected according to the output voltage range of the power supply;

[0018] Furthermore, the screw thickness and the front end small hole diameter should correspond to the corresponding particle size;

[0019] Beneficial effects of the present invention:

[0020] (1) The Faraday cup with storage bin design proposed in the present invention solves the problem that the Faraday cup collector has a small capacity and cannot measure the charge of multiple particles.

[0021] (2) The magnet fixing device and the design of the magnet and drift tube proposed in the present invention can shield the plasma from entering the Faraday cup, thereby solving the problem that the plasma beam will enter the Faraday cup and thus cannot capture the particle charge.

[0022] (3) The drift tube design proposed in the present invention can change the sheath structure in the channel by adding a bias voltage, thereby solving the problem of the change in charge of particles entering the sheath when passing through the channel.

[0023] (4) The controllable particle dropping device proposed in the present invention can control the individual dropping of particles of different particle sizes, thereby solving the problem that a large number of particles simultaneously enter the Faraday cup and the signals cannot be distinguished.

[0024] (5) The controllable particle dropping device proposed in the present invention can control the individual particle dropping by means of a push-pull electromagnet, thereby solving the problem that the device cannot be manually controlled in a laboratory.

[0025] (6) The design of using a charge sensitive amplifier after the Faraday cup proposed in the present invention can measure tiny charges, solving the problem that the traditional Faraday cup cannot measure smaller charges. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a Faraday cup device with a storage bin according to an embodiment of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of a controllable particle dropping device according to an embodiment of the present invention;

[0028] Figure 3 A system diagram of a method and device for measuring the charge of particles in plasma according to an embodiment of the present invention;

[0029] Figure 4 is a typical signal curve diagram of an embodiment of the present invention;

[0030] Figure 5 A graph showing the relationship between particle charge and particle size in a plasma environment measured in an embodiment of the present invention;

[0031] 1-metal charge collector, 2-collector base, 3-base storage bin, 4-shielding shell, 5-shielding cover, 6-drift tube, 7-insulating base, 8-insulating top cover, 9-magnet, 10-magnet fixing device, 11-rear of the main body, 12-particle track, 13-right of the main body, 14-screw, 15 push-pull electromagnet fixing hole, 16-controllable particle drop device, 17-plasma source, 18-Faraday cup device with storage bin DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions in the patent application of the present invention, the technical solutions in the present application are clearly and completely described below in conjunction with the drawings in the present application. Obviously, the described implementation methods are only part of the implementation methods of the present application, not all implementation methods. Based on the implementation methods in the present application, all other implementation methods obtained by ordinary technicians in the field without making creative work should fall within the scope of protection of the present application.

[0033] Embodiment 1:

[0034] Figure 1The structure diagram of the Faraday cup device with a storage bin according to an embodiment of the present invention is shown in FIG. The bottom surface of the bowl-shaped metal charge collector 1 is inclined, and a through hole slightly larger than the diameter of the measured particle is opened at the bottom corner for the particle to enter the storage bin. The bottom is slotted for signal line welding. The collector base 2 and the base storage bin 3 are originally an integrated structure for fixing and supporting the metal charge collector. The base storage bin 3 is used to collect the incoming particles. The shielding shell 4 and the shielding cover 5 form a complete shielding layer for grounding. The Faraday cage principle is used to prevent the metal charge collector 1 signal from being interfered by the outside world. The insulating base 7 and the insulating top cover 8 form a complete insulating support as the outer shell of the entire Faraday cup. The drift tube 6 is placed on the insulating top cover 8 for plasma shielding and changing the sheath thickness to reduce its influence on the particle charge. The magnet 9 is installed in the magnet fixing device 10, and the magnet fixing device 10 is fixed around the insulating top cover 8. The function of the magnet 9 is to generate a magnetic field in the shielding tube to shield the plasma. The charged particles enter the Faraday cup through the drift tube, while the rest of the plasma is shielded to achieve the purpose of measuring the particle charge in the plasma environment.

[0035] Figure 2 This is a schematic diagram of the structure of a controllable particle dropping device according to an embodiment of the present invention. The rear part 11 of the main body, the left part of the main body and the right part 13 of the main body constitute a complete main body. A slot 12 is opened in the right part 13 of the main body for storing and passing particles and controlling the particle size. A vertical hole is opened at the front end of the screw 14 for controlling the passage of a single particle. A horizontal threaded hole is opened at the rear end to connect with a push-pull electromagnet. The push-pull electromagnet is fixed to the rear part 11 of the main body through a fixing hole 15. The particles can be controlled to drop one by one in sequence by controlling the switch of the push-pull electromagnet.

[0036] Embodiment 2:

[0037] Figure 3 The method and device system diagram of measuring the charge of particles in plasma according to an embodiment of the present invention, the controllable particle drop device 16 controls particles of different sizes to fall one by one, and passes through a plasma area. The plasma area is provided by different plasma sources 17, including but not limited to hot tungsten wires, hollow cathodes, various ion sources and electric thrusters. After passing through the plasma area, the particles enter the Faraday cup device 18 with a storage bin, are collected by the metal charge collector 1, and are transmitted to the subsequent signal processing circuit. The signal processing circuit mainly includes a charge sensitive amplifier and a filter, the main purpose of which is to convert 10 -13 The charge amplification of the C level is easy to measure with good signal-to-noise ratio and the voltage signal of tens of millivolts to several volts can be eliminated, and the 50HZ power frequency interference generated by electrical appliances can be eliminated.

[0038] In addition, the foregoing only describes some embodiments, which may be changed, modified, added and / or varied without departing from the scope and essence of the disclosed embodiments, which are illustrative rather than restrictive. In addition, the described embodiments relate to the embodiments currently considered to be the most practical and preferred, and it should be understood that the embodiments should not be limited to the disclosed embodiments, but rather, are intended to cover different modifications and equivalent arrangements included within the essence and scope of the embodiments. In addition, the various embodiments described above may be used in conjunction with other embodiments, such as aspects of one embodiment may be combined with aspects of another embodiment to achieve yet another embodiment. In addition, each independent feature or component of any given component may constitute another embodiment.

[0039] The foregoing description of the embodiment is provided for the purpose of illustration and description, and is not intended to be exhaustive or limit the present disclosure. Each element or feature of a specific embodiment is generally not limited to the specific embodiment, but in the applicable case, even if not specifically shown or described, each element or feature is also interchangeable and can be used for the selected embodiment, and can also be changed in a variety of ways. This change is not considered to be a deviation from the present disclosure, and all of these changes are included in the scope of the present disclosure. Therefore, it should be understood that the drawings and description are provided here by way of example to facilitate the understanding of the present invention, and should not constitute a limitation on its scope.

Claims

1. A method and device for measuring the charge of particles in plasma, specifically including a Faraday cup device structure design with a storage bin and a controllable particle dropping device. in A Faraday cup device with a storage bin, comprising: a metal charge collector (1), a collector base (2), a base storage bin (3), a shielding shell (4), a shielding cover (5), a drift tube (6), an insulating base (7), an insulating top cover (8), a magnet (9), and a magnet fixing device (10); a controllable particle dropping device, comprising a main body rear (11), a main body right (13), a main body left, a push-pull electromagnet, and a screw (14); The metal charge collector (1) is placed in the collector base (2) and is positioned by a positioner and a positioning hole. The collector base (2) is coaxially placed on the base storage bin (3) and is bonded and fixed to the base storage bin (3). The collector base (2) and the base storage bin (3) are placed inside a shielding shell (4) and a shielding cover (5). The shielding shell (4) and the shielding cover (5) form a complete shielding layer. The shielding cover (5) has a through hole with a diameter 2-3 times that of the measured particle (for example, the diameter of the groove is 4-6 mm for particles with a diameter of 2 mm) in the center so that the particle can pass through. The shielding layer is placed inside an insulating base (7) and an insulating top cover (8). The insulating base (7) and the insulating top cover (8) form a complete insulating layer. The insulating top cover (8) has a through hole with a diameter 2-3 times that of the measured particle (for example, the diameter of the groove is 4-6 mm for particles with a diameter of 2 mm) in the center. The drift tube (6) is coaxially placed in the through hole at the center of the insulating top cover (8). The magnet (9) is fixed in the magnet fixing device (10). The magnet fixing device (10) is fixed around the insulating top cover (8) to generate a magnetic field to shield the plasma. A screw hole is opened in the middle of the rear of the main body (11) as a fixing point for the fixing screw. The right side of the main body (13) is fixed to the rear of the main body with screws. The surface of the right side of the main body (13) is grooved (12). The depth and width of the groove (12) are adapted to the size of the particles passing through. For example, if the particle has a diameter of 2 mm, the groove diameter is 2.4 mm. The left side of the main body is an acrylic transparent plate, which is fixed to the right side of the main body (13) with screws. The push-pull electromagnet has a rated voltage of 12V and is fixed on the rear of the main body (11). The screw (14) is fixed to the front end of the push-pull electromagnet and a vertical small hole is opened at the front end for particles to pass through.

2. A Faraday cup device with a storage bin structure design as claimed in claim 1, characterized in that: The metal charge collector can be made of copper, brass, silver and other conductive and non-magnetic metals. A through hole slightly larger than the diameter of the measured particles is opened at the lowest point to allow the particles to pass through, and a groove is opened at the bottom to weld the wire.

3. The structural design of a Faraday cup device with a storage bin as claimed in claim 1, characterized in that: The shielding shell, the shielding cover and the drift tube can be made of conductive and non-magnetic metals such as copper, brass, and silver.

4. The structural design of a Faraday cup device with a storage bin as claimed in claim 1, characterized in that: The collector base, base storage bin, insulating base, and insulating top cover can be made of insulating materials with certain strength and high temperature resistance, such as epoxy resin and acrylic.

5. The structural design of a Faraday cup device with a storage bin as claimed in claim 1, characterized in that: The magnet fixing device can be made of conductive and non-magnetic metals such as copper, brass, and silver, or insulating materials with certain strength and high temperature resistance such as epoxy resin and acrylic.

6. The structural design of a Faraday cup device with a storage bin as claimed in claim 1, characterized in that: The magnet can be a permanent magnet of various materials such as a neodymium iron boron magnet, an aluminum nickel cobalt magnet, or an electromagnet with a suitable number of turns.

7. A controllable particle dropping device as claimed in claim 1, characterized in that: The right body and the rear body can be made of any material with certain strength and high temperature resistance.

8. A controllable particle dropping device as claimed in claim 1, characterized in that: The main body can be made of any transparent material with certain strength and high temperature resistance.

9. A controllable particle dropping device as claimed in claim 1, characterized in that: The rated voltage of the push-pull magnet can be arbitrarily selected according to the output voltage range of the power supply.

10. A controllable particle dropping device as claimed in claim 1, characterized in that: The thickness of the screw and the diameter of the small hole at the front end should correspond to the corresponding particle diameter size.

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