CN107037275B - A kind of device measuring single charged particle charge-mass ratio - Google Patents

Abstract

The invention provides a device for measuring the charge-to-mass ratio of a single charged particle, which can measure the charge-to-mass ratio of a single charged particle, has a simple structure and is easy to operate. The device can get more accurate measurement results. It includes a uniform electric field generating device and a grating ranging system. The uniform electric field generating device is used to make the charged particles move uniformly in the uniform electric field generated by the uniform electric field generating device. The grating ranging system is used to obtain the charged particles in the uniform electric field. Based on the trajectory of the strong electric field motion, the charge-to-mass ratio of the charged particles is determined based on the corresponding relationship between the trajectory of the uniformly accelerated motion and the external force.

Description

A device for measuring the charge-to-mass ratio of a single charged particle

technical field

The invention relates to the technical field of charge-to-mass ratio measurement, in particular to a device for measuring the charge-to-mass ratio of a single charged particle.

Background technique

Charged water mist has important application prospects in the fire prevention of important places such as aviation, aerospace, ships, etc. The essence of which is the complex interaction between charged droplets and flames. Studying the interaction between a single charged droplet and flames is important for It is of great significance to understand the fire extinguishing mechanism of charged water mist, improve the fire extinguishing effect of charged water mist, and promote the practical application of charged water mist fire extinguishing technology. The charge-to-mass ratio is an important index to measure the charged droplets, so the accurate measurement of the charge-to-mass ratio of a single charged droplet is a key issue.

Researchers at home and abroad have done a lot of research on the measurement device of the charge-to-mass ratio. According to the principle, it can be roughly divided into two types: one is the Faraday cylinder method, which uses the principle of electrostatic induction to measure the charge of the droplet, and uses a balance to measure the charge of the droplet. mass, so as to obtain the charge-to-mass ratio of droplets. For example, the application number is 201310359398.3, and the name is "a real-time measurement device for the charge-to-mass ratio of charged droplets that is easy to disassemble." It is based on the Faraday cage method; the other is the mesh target method. The charge-to-mass ratio is studied by using the principle of measuring the micro-current and collecting the deposited droplets to measure the flow rate. For example, the application number is 201420831496.2, and the name is "a detection device for the charge-to-mass ratio of electrostatic nozzle droplets". However, the charge-to-mass ratio measuring device obtained based on the above-mentioned principle is all charged droplets. For a charged droplet, especially a droplet with a small charge, it is difficult to obtain accurate measurement results by the above-mentioned method.

Contents of the invention

The object of the present invention is to provide a device for measuring the charge-to-mass ratio of a single charged particle, and propose a measuring device capable of measuring the charge-to-mass ratio of a single tiny charged particle for a single charged particle.

Technical scheme of the present invention is:

1. A device for measuring the charge-to-mass ratio of a single charged particle is characterized in that it comprises a uniform electric field generating device and a grating distance measuring system, and the uniform electric field generating device is used to make the charged particle generate in a uniform electric field generating device Performing uniform acceleration motion in a uniform electric field, the grating ranging system is used to obtain the trajectory of the charged particles moving in the uniform electric field; the grating ranging system produces an array of optical axes with a certain distance, when the charged particles When moving in middle, the moment when the charged particle passes the first optical axis is recorded as 0, and the time t _i (i=1,2,3...) and the moment when the charged particle passes the i+1th optical axis are measured and Time t _j (j=1,2,3...) when passing the j+1th optical axis

By the formula:

The charge-to-mass ratio of a single charged particle can be obtained: where, q is the charge of a single charged particle, m is the mass of a single charged particle, E is the electric field intensity of a uniform electric field, and d ₀ is the distance between two adjacent optical axes the distance.

2. The uniform electric field generating device comprises a direct-current high-voltage generator, an electrostatic voltmeter, and two flat-plate electrodes parallel to each other; the output end of the direct-current high-voltage generator is connected with one flat-plate electrode by a wire, and the other flat-plate electrode is grounded , thereby generating a uniform electric field; the electrostatic voltmeter is connected in parallel with the high voltage generator.

3. The direction of the uniform electric field generated by the two parallel flat electrodes is perpendicular to the direction of gravity, and the charged particles drop freely into the uniform electric field.

4. The two parallel flat electrodes are copper plates, and the outer surface of each copper plate is sequentially inlaid with polytetrafluoroethylene and insulating plexiglass.

5. The distance D between the two copper plates is ≥ 5cm.

6. The diameter of the charged particles is ≤5%D, so as to ensure that the influence of the electric field generated by the charges on the charged particles on the uniform electric field can be ignored.

7. The grating ranging system includes a transmitter, a light receiver, a computer or a controller, and a synchronous timer. The transmitter and the light receiver are placed in parallel, and equidistant distances are generated between the transmitter and the light receiver. The optical axis array, the optical receiver is connected with the computer, and the computer/controller is connected with the synchronous timer.

8. The emitter is a laser emitter, and the laser optical axis array at equal intervals generated is perpendicular to the direction of the uniform electric field generated by the uniform electric field generating device, and the charged particles can pass through the laser.

9. The optical axis distance d ₀ of the optical axis array can be adjusted according to the diameter of the charged particles, and the relationship between the optical axis distance d ₀ and the diameter of the charged particles is: the diameter of the charged particles ≤ 10% d ₀ .

10. The charged particles are charged droplets, including insulating dielectric droplets or conductive electrolyte droplets.

Technical effect of the present invention:

A device for measuring the charge-to-mass ratio of a single charged particle proposed by the present invention can measure the charge-to-mass ratio of a single charged particle, and has a simple structure and is easy to operate. Compared with the device, more accurate measurement results can be obtained.

Description of drawings

Fig. 1 is a schematic diagram of the measurement principle of the device for measuring the charge-to-mass ratio of a single charged particle of the present invention.

Fig. 2 is a schematic structural diagram of an embodiment of a device for measuring the charge-to-mass ratio of a single charged particle of the present invention.

Fig. 3 is a schematic diagram of the structure of the plate electrode.

Reference signs are listed as follows: 1-DC high voltage generator, 2-electrostatic voltmeter, 3-plate electrode, 4-emitter, 5-receiver, 6-computer, 7-synchronous timer, 33-copper plate , 32-polytetrafluoroethylene plate, 31-insulated plexiglass plate.

Detailed ways

Embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings, but they are not used to limit the scope of the present invention.

A device for measuring the charge-to-mass ratio of a single charged particle, comprising a uniform electric field generating device and a grating ranging system, the uniform electric field generating device is used to make the charged particles uniformly move in the uniform electric field generated by the uniform electric field generating device Accelerated movement, the grating ranging system is used to obtain the trajectory of charged particles moving in a uniform electric field; the grating ranging system produces an optical axis array with a certain distance, when the charged particles move in a uniform electric field, the charged particles will The moment when the particle passes through the first optical axis is recorded as 0, and the time t _i (i=1,2,3...) when the charged particle passes through the i+1th optical axis and the time when the charged particle passes through the j+1th optical axis are measured. Time t _j of optical axis (j=1,2,3...)

By the formula:

The charge-to-mass ratio of a single charged particle can be obtained: where, q is the charge of a single charged particle, m is the mass of a single charged particle, E is the electric field intensity of a uniform electric field, and d ₀ is the distance between two adjacent optical axes the distance.

As shown in FIG. 1 , it is a schematic diagram of the measurement principle of the present invention. Assuming that the single charged particle is a charged droplet, the charged droplet enters the uniform electric field generated by two parallel electrode plates, and under the joint action of gravity and electric field force, its trajectory is a parabola; due to gravity and electric field If the forces are perpendicular to each other, the motion of the charged droplet can be decomposed into uniformly accelerated linear motion in the vertical direction (gravity action) and uniformly accelerated linear motion in the horizontal direction (action by electric field force); The electric field force received, thereby obtaining the charge-to-mass ratio. If the voltage difference between the two polar plates is U, the horizontal distance between the two polar plates is D, E ₀ is the intensity of the uniform electric field formed between the two polar plates, and the optical axis distance of the optical axis array generated by the grating ranging system is d ₀ , The moment when the charged droplet passes through the first optical axis is recorded as 0, t _i (i=1,2,3...) is the moment when the charged droplet passes through the i+1th optical axis, t _j (j= 1,2,3...) is the moment when the charged droplet passes through the j+1th optical axis, assuming that the charge amount of the droplet is q and the mass is m, then the horizontal acceleration of the droplet is:

For a uniform electric field, from the relationship between electric field force and acceleration:

Combining the above two equations, the charge-to-mass ratio of the charged single droplet is obtained as:

In the formula, d ₀ , U, D can be directly and accurately set, only need to measure the time t _i (i=1,2,3...) when the charged droplet passes through the i+1th optical axis and the The time t _j (j=1, 2, 3 . . . ) of the j+1th optical axis is sufficient.

As shown in FIG. 2 , it is a schematic structural diagram of an embodiment of a device for measuring the charge-to-mass ratio of a single charged particle of the present invention.

The measuring device in the embodiment of the present invention is mainly composed of a uniform electric field generating device and a grating ranging system. The uniform electric field generating device includes: electrostatic voltmeter 2, DC high-voltage generator 1, and two parallel plate electrodes 3; the output end of DC high-voltage generator 1 is connected to one plate electrode through a wire, and the other plate electrode is grounded , so that a uniform electric field is generated between two parallel plate electrodes 3; the output terminal of the electrostatic voltmeter 2 is also connected in parallel with the high-voltage generator, and the grounding joint is grounded; the wires are all 40kV high-voltage shielded wires. The grating distance measuring system includes: a transmitter 4, a receiver 5, a computer (or controller) 6, a synchronous timer 7, the transmitter 4 and the receiver 5 are placed in parallel, and the distance between the transmitter 4 and the receiver 5 is generated. Equidistant optical axis array, optical receiver 5 is connected with computer 6, and computer 6 is connected with synchronous timer 7. In this embodiment, the flat electrode 3 is made up of two parallel red copper plates 33, as shown in Figure 3, which is a schematic diagram of the flat electrode structure, and the outer surface of each red copper plate is inlaid with a polytetrafluoroethylene plate 32 and an insulating plexiglass plate 31 The distance D between the two copper plates can be adjusted appropriately. In this embodiment, the distance D between the two copper plates is designed to be greater than or equal to 5cm. A high-voltage static electricity of U is applied between two copper plates to form a uniform electric field. During measurement, the direction of the uniform electric field generated by the plate electrode should be perpendicular to the direction of gravity, and the charged liquid droplet falls freely into the uniform electric field. The charged droplet can be an insulating dielectric (such as ultrapure water), or a conductive electrolyte (such as NaCl solutions of different concentrations). The emitter 4 of this embodiment is a laser emitter, and the laser optical axis array with equal intervals produced is perpendicular to the direction of the uniform electric field generated by the uniform electric field generating device, and the charged liquid droplets dropped into the uniform electric field can pass through the laser optical axis array Formed laser light curtain. The charged drop blocks the laser light curtain emitted by the emitter 4, and the light receiver 5 cannot receive the light signal. The computer (or controller) 6 feeds back this reaction to the synchronous timer 7, so that the charged drop passes through each laser light curtain. The time of the optical axis. In addition, the diameter of the charged droplet is ≤5% D, so as to ensure that the influence of the electric field generated by the charges on the charged particles on the uniform electric field can be ignored; the optical axis distance d ₀ of the optical axis array can be adjusted according to the diameter of the charged particles. In an embodiment, the relationship between the optical axis distance d ₀ and the diameter of the charged particle is: the diameter of the charged particle≤10%d ₀ .

It is pointed out here that the above description is helpful for those skilled in the art to understand the present invention, but does not limit the protection scope of the present invention. Any equivalent replacement, modification and improvement and/or simplified implementation of the above descriptions without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. a kind of device for measuring single charged particle charge-mass ratio, which is characterized in that including uniform electric field generation device and light Grid range-measurement system, the uniform electric field that the uniform electric field generation device is used to that charged particle to be made to generate in uniform electric field generation device In do uniformly accelerated motion, the grating range-measurement system is for obtaining charged particle in the track that uniform electric field moves；The grating Range-measurement system generates tool optical axis array at regular intervals and leads to charged particle when charged particle moves in uniform electric field It is denoted as 0 at the time of crossing the 1st optical axis, charged particle is measured and passes through t at the time of i+1 root optical axis_iAnd charged particle passes through jth T at the time of+1 optical axis_j

By formula:

The charge-mass ratio of you can get it single charged particle: where q is the electricity of single charged particle, and m is single charged particle Quality, E are the electric field strength of uniform electric field, d₀For the distance between adjacent two optical axises.

2. the device of the single charged particle charge-mass ratio of measurement according to claim 1, which is characterized in that the uniform electric field Generation device includes high voltage direct current generator, electrostatic voltmeter, two plate electrodes being parallel to each other；The high direct voltage occurs The output end of device is connected by conducting wire with a plate electrode, another plate electrode ground connection, to generate uniform electric field；Institute It is in parallel with high pressure generator to state electrostatic voltmeter.

3. the device of the single charged particle charge-mass ratio of measurement according to claim 2, which is characterized in that described two mutual The uniform electric field direction and gravity direction that parallel plate electrode generates are perpendicular, and the charged particle freely falling body instills even strong Electric field.

4. the device of the single charged particle charge-mass ratio of measurement according to claim 3, which is characterized in that described two mutual Parallel plate electrode be copper plate, the outside of each copper plate successively inlaid polytetrafluoroethylsliders and insulation organic glass.

5. the device of the single charged particle charge-mass ratio of measurement according to claim 4, which is characterized in that described two red coppers The distance between plate D >=5cm.

6. the device of the single charged particle charge-mass ratio of measurement according to claim 5, which is characterized in that the charged particle Diameter≤5%D, with guarantee charged particle influence of the electric field to uniform electric field of electrically charged generation can ignore.

7. the device of the single charged particle charge-mass ratio of measurement according to claim 1, which is characterized in that the grating ranging System includes transmitter, light receiving device, computer or controller, synchrotimer, and the transmitter and light receiving device are placed in parallel, institute It states and generates equidistant optical axis array between transmitter and light receiving device, the light receiving device is connected with computer or controller, calculates Machine or controller are connected with synchrotimer.

8. the device of the single charged particle charge-mass ratio of measurement according to claim 7, which is characterized in that the transmitter is Laser emitter, the uniform electric field that the equidistant laser beam axis array of generation is generated perpendicular to the uniform electric field generation device Direction, the charged particle can pass through laser.

9. the device of the single charged particle charge-mass ratio of measurement according to claim 7 or 8, which is characterized in that the optical axis The optical axis of array is away from d₀It can be adjusted according to the diameter of charged particle, the optical axis is away from d₀With the relationship of charged particle diameter It is: diameter≤10%d of charged particle₀。

10. the device of the single charged particle charge-mass ratio of measurement according to claim 1, which is characterized in that the electrification Grain is charged drop, the electrolyte drop of dielectric drop or conduction including insulation.