CN111787677A

CN111787677A - Magnetic deflection Faraday probe for measuring ion velocity of charge exchange collision

Info

Publication number: CN111787677A
Application number: CN202010423703.0A
Authority: CN
Inventors: 章喆; 汤海滨; 许舒婷; 张尊
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2020-10-16
Anticipated expiration: 2040-05-19
Also published as: CN111787677B

Abstract

The invention provides a magnetic deflection Faraday probe for measuring the speed of ion collision of exchange charges. And measuring the low-speed plasma at the edge of the beam area of the electric thruster by adopting a contact measurement method to obtain the ion velocity distribution of the plume of the ion thruster. The structure specifically includes: faraday collectors, ceramic insulating gaskets, collimation ports, pig iron sheets, energized solenoids and silicon steel casings. A uniform magnetic field is formed between the pig iron sheets by electrifying the electrified solenoid, incident charged ions are incident through a quasi-orthogonal angle, and particles with different motion speeds are deflected by the magnetic field to reach the Faraday collector. Ions with different speeds can be calculated and screened out according to the Larmor cyclotron radius.

Description

Magnetic deflection Faraday probe for measuring ion velocity of charge exchange collision

Technical Field

The invention belongs to the field of electric propulsion plasma diagnosis, and particularly relates to a magnetic deflection Faraday probe for measuring the speed of ion collision of exchanged charges.

Background

Electric propulsion is an advanced propulsion mode which utilizes electric energy to directly ionize propellants and accelerates charged particles to be sprayed out through an electromagnetic field so as to obtain propulsion power. Compared with the traditional chemical propulsion mode, the electric propulsion has the remarkable advantages of high specific impulse and high efficiency, and has wide application prospect in space tasks of large-scale spacecraft, such as orbit control, deep space exploration, interstellar navigation and the like. The electric thruster is widely applied to the main propulsion system of the satellite and the deep space probe at present.

The measurement of relevant parameters of the plume plasma of the electric thruster is of great significance for improving the design of the optimized engine and improving the performance of the engine. The ion speed sprayed by the electric thruster directly determines the size and efficiency of the specific impulse of the engine, so that the measurement of the plasma speed distribution is a crucial link in plasma diagnosis of the electric thruster. However, the charged particles ejected from the electric thruster are not all at high speed, and some of the high-speed ions collide with neutral atoms to generate low-speed charged ions. The low-speed charged ions have random directions, and can generate sputtering and deposition pollution on the surface of an aircraft, so that the overall working performance of the satellite is influenced. There is currently no diagnostic method that specifically measures low energy ions generated by exchange charge collisions.

Disclosure of Invention

The invention aims to design a magnetic deflection Faraday probe for measuring the speed of ions collided by exchange charges so as to measure the speed distribution of low-speed ions in a plume jetted by an engine. The specific contents are as follows:

a magnetically deflectable faraday probe for measuring the velocity of exchanged charge-collided ions comprising: faraday collectors, ceramic insulating gaskets, collimating ports, pig iron sheets, energized solenoids, and silicon steel housings. The Faraday collector is inserted in the ceramic insulating gasket, and the ceramic insulating gasket is arranged on the silicon steel shell through tight fit; an electrified solenoid is arranged in the silicon steel shell, and two ends of the solenoid are connected with the pig iron sheet. The opposite surface of the silicon steel shell and the Faraday collector is provided with a collimation opening with the diameter of 8 mm.

Furthermore, the shell of the Faraday probe collector is made of silicon steel.

Further, the Faraday collector adopts negative bias potential of-10V.

Furthermore, the collimation angle of the collimation opening is 4 degrees, and the direction of screening incident ions is less than 4 degrees.

Furthermore, the propellant of the electric thruster measured by the Faraday probe is selected from single-component rare gas including argon and xenon.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention measures the directional movement speed of low-energy charged ions by a measuring mode of deflecting low-speed charged ions by a magnetic field, the Larmor gyration radius of the magnetic deflection mode is larger, the measuring precision is effectively improved, and the measuring precision of the invention is higher than that of a testing method adopting an electric field to screen ions.

(2) The invention adopts the magnetic field applying mode of the electromagnet, namely the electrified solenoid, the intensity of the electrified current determines the intensity of the magnetic field, and the uniformity and the adjustability of the magnetic field are realized. The variable magnetic field enables the magnetic deflection Faraday probe to measure the speed of ions in different energy ranges, and the measuring range and the application range of the instrument are improved.

(3) The shell of the Faraday collector is made of silicon steel materials, so that the Faraday collector plays a role of magnetic shielding, prevents magnetic induction lines from leaking, and minimizes the influence of a measuring instrument on the speed distribution of the measured plasma.

(4) The invention stipulates that the quasi-right angle of the incident ions is 4 degrees, ensures that the charged ions and the additional magnetic field vertically enter the instrument, and shields the charged ions in other directions from being collected by the Faraday collector; the method ensures the singleness of the direction of the entered ions and is convenient for model calculation.

Drawings

FIG. 1 is a schematic diagram of the process of collision and formation of the exchange charge ions of the present invention.

Fig. 2(a) is a top view of a magnetically deflected faraday probe of the present invention.

Figure 2(b) is a 3-D schematic of a magnetically deflected faraday probe of the present invention.

Figure 2(c) is a side view of a magnetically deflected faraday probe of the present invention.

Figure 2(d) is a front view of a magnetically deflected faraday probe of the present invention.

Figure 3 is a graph of the magnetic field distribution and ion deflection trajectories of ions within a magnetically deflected faraday probe of the present invention.

The device comprises a collector 1, a Faraday collector 2, a ceramic insulating gasket, a collimating port 3, a pig iron sheet 4, an electrified solenoid 5 and a silicon steel shell 6.

Detailed Description

The invention will be described in more detail with reference to the following figures and examples, but the scope of the invention is not limited thereto.

The diagnostic measurement object of the present invention is a process of collision and formation of exchange charge ions (fig. 1), including ions with fast movement speed and atoms with slow movement speed; the ions moving at high speed collide with the atoms moving at low speed, and the atoms exchange the carried extra-nuclear electrons for the ions in the collision process, so that the collision process is subjected to component conversion, the original high-speed ions are subjected to electron recombination to become high-speed atoms, and the slow neutral atoms lose electrons and become low-speed charged ions. Thus, low-speed, randomly-directed charged ions are generated in the entire process. These ions are slow, random in direction, and intermingled with high-speed ions, are easily deposited on the surface of the airship, and are difficult to detect.

The three-dimensional view of the magnetic deflection Faraday probe provided by the invention, as shown in FIGS. 2(a) - (d), specifically comprises the following steps: 1-Faraday collector, 2-ceramic insulating gasket, 3-collimation port, 4-pig iron sheet, 5-energized solenoid and 6-silicon steel shell. The Faraday collector adopts negative bias potential of-10V to shield the influence of electrons on the collected current, and the electrons cannot be directly shielded by a magnetic field because the cyclotron radius of the electrons is large. The ceramic insulating spacer acts to insulate the faraday collector from the housing. The angle of the collimation opening is 4 degrees, the direction of screening incident ions is less than 4 degrees, and the ions deflected by the magnetic field are ensured to be vertical to the magnetic field. The magnet sheets are connected with the electrified solenoid and are made of magnetic conductive materials, demagnetization speed is high, and the magnetic field intensity formed between the magnet sheets can be adjusted by changing the current on the electrified solenoid, so that deflection of ions with different speeds is completed. The Faraday collector shell is made of silicon steel, and can reduce the influence of the measuring instrument on plasma on magnetic induction lines overflowing from the inside of the magnetic deflection Faraday probe.

The magnetic field distribution and ion deflection trajectory diagram (figure 3) of the ions in the magnetic deflection Faraday probe, the charged ions enter the instrument through the collimation port, the charged ions are deflected under the action of the magnetic field, and only ions with specific speed can reach the surface of the Faraday collector and are collected.

Although exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, substitutions and the like can be made in form and detail without departing from the scope and spirit of the invention as disclosed in the accompanying claims, all of which are intended to fall within the scope of the claims, and that various steps in the various sections and methods of the claimed product can be combined together in any combination. Therefore, the description of the embodiments disclosed in the present invention is not intended to limit the scope of the present invention, but to describe the present invention. Accordingly, the scope of the present invention is not limited by the above embodiments, but is defined by the claims or their equivalents.

Claims

1. A magnetic deflection Faraday probe for measuring the velocity of exchanged charge impact ions, comprising: a Faraday collector, a ceramic insulating gasket, a collimating port, a pig iron sheet, an electrified solenoid and a silicon steel shell; the Faraday collector is inserted in the ceramic insulating gasket, the ceramic insulating gasket is arranged on the silicon steel shell through tight fit, an electrified solenoid is arranged in the silicon steel shell, and two ends of the solenoid are connected with the pig iron sheets; the opposite surface of the silicon steel shell and the Faraday collector is provided with a collimation opening with the diameter of 8 mm.

2. A Faraday probe according to claim 1, wherein the Faraday probe collector housing is of silicon steel.

3. A Faraday probe according to claim 1, wherein the Faraday collector is biased negatively at-10V.

4. A Faraday probe according to claim 1, wherein the collimating aperture has a collimation angle of 4 ° and a screening direction for incident particles of less than 4 °.

5. A Faraday probe according to claim 1, wherein the propellant of the electric thruster measured by the Faraday probe is a single-component rare gas, including argon and xenon.