阅读说明：本技术 电推力器束流测量系统和主系统 (Beam current measuring system and main system of electric thruster ) 是由 蔡国飙 杨祖仪 翁惠焱 贺碧蛟 于 2019-09-24 设计创作，主要内容包括：本发明提供了一种电推力器束流测量系统和主系统,其中,该系统包括：反向比例运算电路、法拉第探针、负偏置电压源和测量仪；其中,反向比例运算电路包括第一电阻和第二电阻；法拉第探针、负偏置电压源和测量仪分别与反向比例运算电路相连接；法拉第探针的测试端和待测量的电推力器喷口面相对。本发明不仅可以减少法拉第探针的测量误差,而且避免了法拉第探针脱离工作区,达到了提高电推力器束流测量精度的效果。(The invention provides a beam current measuring system and a main system of an electric thruster, wherein the system comprises: the device comprises a reverse proportion operation circuit, a Faraday probe, a negative bias voltage source and a measuring instrument; the inverse proportion operation circuit comprises a first resistor and a second resistor; the Faraday probe, the negative bias voltage source and the measuring instrument are respectively connected with the inverse proportion operation circuit; the testing end of the Faraday probe is opposite to the nozzle surface of the electric thruster to be measured. The invention can reduce the measurement error of the Faraday probe, avoid the Faraday probe from separating from the working area and achieve the effect of improving the beam measurement precision of the electric thruster.)

1. The beam current measuring system of the electric thruster is characterized by comprising an inverse proportion operation circuit, a Faraday probe, a negative bias voltage source and a measuring instrument, wherein the inverse proportion operation circuit comprises a first resistor and a second resistor;

the Faraday probe, the negative bias voltage source and the measuring instrument are respectively connected with the inverse proportion operation circuit; the testing end of the Faraday probe is opposite to the nozzle surface of the electric thruster to be measured;

the inverse proportion operation circuit is used for obtaining the current and the output voltage of the second resistor according to the virtual short characteristic and the virtual disconnection characteristic of the inverse proportion operation circuit under the condition that the Faraday probe is disconnected with the inverse proportion operation circuit;

the measuring instrument is used for measuring the current of the first resistor when the negative bias voltage output by the negative bias voltage source and the output voltage meet preset conditions and the Faraday probe is connected with the inverse proportion operation circuit, so that the inverse proportion operation circuit obtains the beam current of the Faraday probe according to the current of the first resistor and the current of the second resistor.

2. The system according to claim 1, wherein the preset conditions include: the range of the negative bias voltage output by the negative bias voltage source is-15V to-30V, and the output voltage is in the voltage range of a preset direct current stabilized voltage supply.

3. The system of claim 1, further comprising a data processing device;

and the data processing equipment is connected with the inverse proportion operation circuit and is used for obtaining the current density of ions according to the beam current.

4. The system according to claim 3, wherein the data processing device is specifically configured to:

calculating the current density of the ions according to the formula:

wherein j is the current density of the ion, I is the beam current of the Faraday probe, A_cIs the collection area of the faraday probe.

5. The system of claim 3, wherein the data processing device is further configured to: and obtaining a beam integral value, beam distribution and a plume angle according to the current density of the ions.

6. The system according to claim 5, wherein the data processing device is specifically configured to:

calculating the beam current integrated value according to the following formula:

wherein, I_beamAnd j is the current density of the ions, and r is the vertical distance between the Faraday probe and the central axis of the electric thruster.

7. The system of claim 1, further comprising a regulated dc power supply; the inverse proportion operation circuit further comprises a third resistor;

the direct-current stabilized power supply is connected with the inverting input end of the inverse proportion operation circuit through the second resistor; the direct current stabilized voltage power supply is also connected with an operational amplifier of the inverse proportion operational circuit; the negative bias voltage source is connected with the non-inverting input end of the inverse proportion operation circuit through the third resistor, the measuring instrument is connected with two ends of the first resistor, and the Faraday probe is respectively connected with the first resistor, the second resistor and the inverse input end of the inverse proportion operation circuit.

8. The system of claim 1, wherein the meter comprises a digital oscilloscope, a voltmeter, or a picoammeter.

9. The system of claim 7, wherein the regulated dc power supply is configured to power the second resistor such that a current of the second resistor is greater than a beam current of the faraday probe.

10. An electric thruster beam measurement master system, characterized in that the master system comprises an electric thruster beam measurement system according to any one of claims 1-9, and further comprises an electric thruster.

Technical Field

The invention relates to the technical field of aerospace instruments, in particular to a beam current measuring system and a main system of an electric thruster.

Background

The vacuum plume of the electric thruster is plasma and mainly comprises ions, electrons, neutral gas molecules and the like, the obtained current density distribution of the beam in the plume is an important index for evaluating the service life of the electric thruster and the plume effect of the electric thruster, and the Faraday probe is a simple means and a method for measuring the spatial ion density distribution. The electric thrusters such as the ion thruster and the Hall thruster are widely applied to attitude and orbit control of the spacecraft due to the advantages of high specific impulse, long service life, small system quality and the like. The accurate acquisition of the vacuum plume parameters of the electric thruster is crucial to the evaluation of the performances of the electric thruster and the spacecraft.

However, in the conventional measurement circuit of the faraday probe, the potential of the probe changes constantly, so that the voltage at the voltage setting end (probe end) of the faraday probe is easy to rise, and insufficient voltage is easy to occur when the beam current is large to a certain extent, thereby causing low measurement accuracy.

Disclosure of Invention

In view of this, an object of the present invention is to provide a faraday probe probing system and a main system, so as to stabilize the negative bias voltage of the faraday probe, reduce the measurement error of the faraday probe, prevent the faraday probe from departing from the working area, and improve the measurement accuracy of the faraday probe.

In a first aspect, an embodiment of the present invention provides a beam current measuring system for an electric thruster, where the system includes a reverse proportion operation circuit, a faraday probe, a negative bias voltage source, and a measuring instrument; the inverse proportion operation circuit comprises a first resistor and a second resistor; the Faraday probe, the negative bias voltage source and the measuring instrument are respectively connected with the inverse proportion operation circuit; the testing end of the Faraday probe is opposite to the nozzle surface of the electric thruster to be measured; the reverse proportion operation circuit is used for obtaining the current and the output voltage of the second resistor according to the virtual short characteristic and the virtual disconnection characteristic of the reverse proportion operation circuit under the condition that the Faraday probe is disconnected with the reverse proportion operation circuit; and the measuring instrument is used for measuring the current of the first resistor when the negative bias voltage and the output voltage output by the negative bias voltage source meet the preset condition and the Faraday probe is connected with the inverse proportion operation circuit, so that the inverse proportion operation circuit obtains the beam current of the Faraday probe according to the current of the first resistor and the current of the second resistor.

With reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, where the preset condition includes: the range of the negative bias voltage output by the negative bias voltage source is-15V to-30V, and the output voltage is in the preset voltage range of the direct current stabilized power supply.

With reference to the first aspect, an embodiment of the present invention provides a second possible implementation manner of the first aspect, where the system further includes a data processing device; and the data processing equipment is connected with the inverse proportion operation circuit and is used for obtaining the current density of the ions according to the beam current.

With reference to the second possible implementation manner of the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, where the data processing device is specifically configured to:

the current density of the ions was calculated according to the following formula:

wherein j is the current density of the ion, I is the beam current of the Faraday probe, A_cIs the collection area of the faraday probe.

With reference to the second possible implementation manner of the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, where the data processing device is further configured to: and according to the current density of the ions, obtaining a beam integral value, beam distribution and a plume angle.

With reference to the fourth possible implementation manner of the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where the data processing device is specifically configured to:

the beam current integral value is calculated according to the following formula:

wherein, I_beamAnd j is the current density of the ions, and r is the vertical distance between the Faraday probe and the central axis of the electric thruster.

With reference to the first aspect, an embodiment of the present invention provides a sixth possible implementation manner of the first aspect, where the system further includes a dc voltage regulator; the inverse proportion operation circuit also comprises a third resistor; the direct current stabilized power supply is connected with the inverting input end of the inverse proportion operation circuit through a second resistor, the direct current stabilized power supply is also connected with an operational amplifier of the inverse proportion operation circuit, the negative bias voltage source is connected with the non-inverting input end of the inverse proportion operation circuit through a third resistor, the measuring instrument is connected with two ends of the first resistor, and the Faraday probe is respectively connected with the first resistor, the second resistor and the inverting input end of the inverse proportion operation circuit.

With reference to the first aspect, an embodiment of the present invention provides a seventh possible implementation manner of the first aspect, where the measuring instrument includes a digital oscilloscope, a voltmeter, or a picoammeter.

With reference to the sixth possible implementation manner of the first aspect, the embodiment of the present invention provides an eighth possible implementation manner of the first aspect, wherein the dc regulated power supply is configured to supply power to the second resistor, so that a current of the second resistor is greater than a beam current of the faraday probe.

In a second aspect, an embodiment of the present invention provides a main system for measuring a beam current of an electric thruster, where the main system includes the beam current measuring system of the electric thruster in any one of the embodiments of the first aspect, and further includes the electric thruster.

The embodiment of the invention has the following beneficial effects: the embodiment of the invention provides a beam current measuring system and a main system of an electric thruster, wherein the system comprises a reverse proportion operation circuit, a Faraday probe, a negative bias voltage source and a measuring instrument, wherein the reverse proportion operation circuit comprises a first resistor and a second resistor; the Faraday probe, the negative bias voltage source and the measuring instrument are respectively connected with the inverse proportion operation circuit; the testing end of the Faraday probe is opposite to the nozzle surface of the electric thruster to be measured; the reverse proportion operation circuit is used for obtaining the current and the output voltage of the second resistor according to the virtual short characteristic and the virtual disconnection characteristic of the reverse proportion operation circuit under the condition that the Faraday probe is disconnected with the reverse proportion operation circuit; and the measuring instrument is used for measuring the current of the first resistor when the negative bias voltage and the output voltage output by the negative bias voltage source meet the preset condition and the Faraday probe is connected with the inverse proportion operation circuit, so that the inverse proportion operation circuit obtains the beam current of the Faraday probe according to the current of the first resistor and the current of the second resistor. In the system, the Faraday probe is connected with the reverse-phase input end of the reverse-phase proportional operation circuit, and the negative bias voltage of the Faraday probe is stabilized on a set value by utilizing the characteristics of the virtual short circuit and the virtual open circuit of the non-inverting input end and the inverting input end in the reverse-phase proportional operation circuit; the negative bias voltage of the Faraday probe is stabilized, so that the measuring error of the Faraday probe can be reduced, the Faraday probe is prevented from being separated from a working area, and the effect of improving the beam current measuring precision of the electric thruster is achieved.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of a Faraday probe measurement circuit according to an embodiment of the present invention;

FIG. 2 is a graph of negative bias voltage versus current density for a Faraday probe measurement according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a beam current measuring system of an electric thruster according to an embodiment of the present invention;

fig. 4 is a schematic circuit structure diagram of a beam current measuring system of an electric thruster according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of another electric thruster beam current measuring system provided in the embodiment of the present invention;

fig. 6 is a signal flow diagram in a beam current measuring system of an electric thruster according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a position relationship between an electrical thruster and a Faraday probe according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a main system for beam current measurement of an electric thruster according to an embodiment of the present invention.

Icon: 10-inverse proportional arithmetic circuit; 20-faraday probe; 30-negative bias voltage source; 40-a measuring instrument; 50-a direct current stabilized power supply; 60-a data acquisition device; 70-a data processing device; 100-beam measuring system of electric thruster; 200-an electric thruster; 300-electric thruster beam current measurement main system.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

FIG. 1 shows a Faraday probe measurement circuit, which includes a DC stabilized voltage supply, a sampling resistor and an oscilloscope. The current value was calculated by generating a potential difference by flowing a current through a resistor and measuring a voltage drop across the resistor using an oscilloscope. When the beam current received by the probe changes, the voltage drop at points a and b in fig. 1 also changes. That is, the probe potential (potential at point b) is changed from moment to moment. If the beam current value change range is 0-10 mA, the resistance value of the sampling resistor R is 2000 omega, and the potential difference between two ends of the resistor is 0-2V. The Faraday probe measures at a certain point in space under the working condition, and the minimum ion saturation negative bias voltage is taken as the bias voltage of the Faraday probe, so that the Faraday probe is very likely to be separated from a working area under the specific working condition due to the phenomenon of potential rise. The resistance of a measuring circuit of the traditional Faraday probe can protect acquisition equipment (an oscilloscope and an ammeter); the current signal received by the faraday probe is converted into a voltage signal which can be measured by an oscilloscope, so that a current density which is averaged with respect to time can be obtained.

In the current Faraday probe measuring circuit, a negative bias voltage is required to be applied to the Faraday probe so as to ensure that the Faraday probe completely repels electrons to independently receive ions and form ion current. If the negative bias voltage changes from large to small, the ion saturation current has a curve, see fig. 2, and when the proper negative bias voltage is reached, the minimum ion saturation negative bias voltage is reached, at this time, the collector can completely repel electrons, collect ions and generate current, and the current density of the ions can be obtained. Further, the beam current increases and the accuracy decreases when the negative bias voltage is continuously decreased, so that the negative bias voltage cannot be decreased without limitation. Therefore, the lowest ion saturation negative bias voltage is an effective method for increasing the acquisition precision of the Faraday probe. However, the conventional faraday probe measurement circuit has the disadvantages that the voltage of the voltage setting end (probe end) of the faraday probe is easily raised, and the insufficient voltage is easily generated when the beam current is large to a certain degree, thereby causing low measurement accuracy.

Based on the above, the beam current measuring system and the main system of the electric thruster provided by the embodiment of the invention can stabilize the negative bias voltage of the faraday probe on a set value, reduce the measurement error of the faraday probe and improve the measurement accuracy of the faraday probe.

For the convenience of understanding the embodiment, a detailed description will be given to a beam current measuring system and a main system of the electric thruster disclosed by the embodiment of the invention.