Time-of-flight mass spectrometer apparatus for characterization of different angle performance of electrospray thrusters

Abstract

Time of flight mass spectrometer device for characterizing different angle performance of electrospray thruster belongs to the field of test of launch performance of electrospray thruster.The present application comprises a time of flight mass spectrometer device, a thruster rotating system, a thruster, a power supply system and a data acquisition device.The time of flight mass spectrometer device comprises an electrostatic gate device, a particle flight tube section and a collection device.The thruster device comprises an electrospray thruster, an electrospray thruster rotating system and a fixing device.The collection device is a stainless steel circular tube with a flange, and an insulating gasket, a metal grid and a collection plate are arranged in the circular tube.The present application wraps the transmission line for transmitting the current signal on the transmission collection plate with a metal mesh to reduce electromagnetic interference.The launch angle of the electrospray thruster is controlled by an electric rotating table outside the vacuum chamber, the rotating angle of the thruster is accurately controlled, the plume velocity of the electrospray thruster under different angles is measured, and the thrust and specific impulse of the electrospray thruster under different angles are calculated through the measured data.

Description

Technical Field

[0001] This invention belongs to the field of electrospray thruster launch performance testing, and relates to a time-of-flight mass spectrometry device for characterizing the performance of electrospray thrusters. Background Technology

[0002] In recent years, electrospray thrusters have been widely used in microsatellite space missions. Measuring electrospray thrusters is crucial for improving their key performance characteristics. Time-of-flight (TOF) testing can determine the type of particles emitted, thrust, and specific impulse of the electrospray thruster; these are important indicators for evaluating its performance, and these parameters can help determine whether the thruster's performance meets requirements.

[0003] Time-of-flight (TOF) is an important method for measuring the velocity of microscopic particles. This method measures the time it takes for a particle to travel a known distance, and then calculates the particle's velocity. The TOF method can measure the plume velocity of electrospray thrusters, and the particle's time of flight is obtained from the electrical properties of the plume particles.

[0004] Currently, all methods for measuring the plume velocity of electrospray thrusters have certain shortcomings:

[0005] (1) Excessive electromagnetic interference. Because the thrust generated by the electro-spray thruster is small, fewer particles penetrate the grid, and some particles deflect onto the pipe wall. The current collected by the collecting plate is very small. If the electromagnetic interference is too large, it will lead to inaccurate measurement results.

[0006] (2) High space requirements. Since the measurement method requires the particle to fly a certain distance, the overall size of the measuring device must meet the measurement requirements. Therefore, measuring the velocity inside the vacuum chamber requires a large space, and it is not convenient to measure in a small vacuum chamber.

[0007] (3) The performance characterization measurement system for the electro-spray thruster did not measure the electro-spray thruster at different angles, but only performed TOF measurement in the positive direction of the electro-spray thruster. Summary of the Invention

[0008] This invention addresses the characteristics of charged particles in the plume generated by an electrospray thruster. The primary objective is to provide a time-of-flight mass spectrometry (TOF-MS) device for characterizing the performance of an electrospray thruster at different angles. This device enables performance characterization of the electrospray thruster, measurement of the plume velocity at various angles, identification of particle types based on test results, and calculation of the thrust and specific impulse at different angles using measurement data. This invention also offers the following advantages: ① shielding against electromagnetic interference; ② flange connection to the vacuum chamber from outside; ③ precise control of the thruster's rotation angle via an electrically operated rotary table, allowing for precise rotation angle control.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] The present invention discloses a time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles, comprising a time-of-flight mass spectrometry device, a thruster rotation system, a thruster, a power supply system, and a data acquisition device.

[0011] The time-of-flight mass spectrometer includes an electrostatic gate, a particle flight tube, and a collection device. The electrostatic gate is a flanged stainless steel tube containing an insulating gasket, a metal grid, and a metal gasket with a central hole. The size of the central hole can change the particle inflow rate. The electrostatic gate is horizontally connected to the particle flight tube via flanges. Both ends of the particle flight tube have flanges. The collection device is horizontally connected to the particle flight tube via another flange. The collection device is also a flanged stainless steel tube containing an insulating gasket, a metal grid, and a collection plate. The thruster rotation system includes a thruster system, an electric rotary table, and a fixing device. The fixing device consists of an adapter plate and a Z-axis lifting platform. The thruster system includes an electrospray thruster and a thruster housing. The electric rotary table is connected to an external control system via control lines.

[0012] The thruster device includes an electro-spray thruster, an electro-spray thruster rotation system, and a fixing device.

[0013] The power supply system includes an adjustable high-voltage DC power supply and a high-voltage pulse power supply.

[0014] The data acquisition device includes a current amplifier and an oscilloscope.

[0015] Furthermore, the electrostatic gate device includes a flanged stainless steel round tube, an insulating gasket, a metal grid, and a circular metal gasket. The metal grid is placed on the groove of the insulating gasket, and the notch on the metal grid coincides with the protrusion of the insulating gasket. The insulating gasket, metal grid, and metal gasket are inside the round tube, with the metal gasket at the tube opening. Following this are the insulating gasket and the metal grid, totaling four insulating gaskets and three metal grids. The insulating gasket, metal grid, and metal gasket are tightly fitted together and connected and fixed to the round tube with bolts. The adapter plate is used to connect and fix the Z-axis lifting platform to the electric rotary platform and is installed between the electric rotary platform and the Z-axis lifting platform.

[0016] Furthermore, the collecting device includes a flanged stainless steel round tube, an insulating gasket, a metal grid, a collecting plate, a disc flange, and a spring. The metal grid and the collecting plate are placed on the groove of the insulating gasket, and the notches on the metal grid and the collecting plate coincide with the protrusions of the insulating gasket. The insulating gasket, the grid, and the collecting plate are placed sequentially at the tube opening. The static gate has three insulating gaskets, one grid, and one collecting plate. The spring is placed between the disc flange and the last insulating gasket, and contacts both of them. The thruster housing can fix the thruster at the center position of the Z-axis lifting platform.

[0017] Furthermore, the flanges of the electrostatic gate device, particle flight tube section, and collection device are the same size and are connected by bolts; the adapter plate has different threaded holes for connecting and fixing the Z-axis lifting platform to the electric rotary table; the thruster housing is made of metal and has screw holes on both sides for fixing the thruster at the center position of the Z-axis lifting platform.

[0018] Furthermore, there are sealing rings between the electrostatic gate device, the particle flight tube section, and the flange of the collection device.

[0019] Furthermore, the insulating pad, metal grid, and circular metal pad with a central hole in the electrostatic gate device all have four evenly distributed circular holes for bolt connection.

[0020] Furthermore, the flanged stainless steel tube of the electrostatic gate device has a circular hole in its wall for inserting a high-voltage connector.

[0021] Furthermore, the metal gasket inside the electrostatic gate device has a circular hole in the center, which is used to adapt and replace metal gaskets with different hole sizes.

[0022] Beneficial effects:

[0023] 1. This invention discloses a time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles. An electrostatic gate device is fixedly connected to the vacuum chamber and particle flight tube section via flanges. A circular tube extends into the vacuum chamber. The flanges have four bolt holes, and three flanges are connected and fixed using bolts and nuts. The collection device is also fixedly connected to the particle flight tube section via flanges. A high-voltage connector on the electrostatic gate device is connected to a pulsed power supply outside the vacuum chamber via a shielded wire. A metal grid is grounded by connecting a wire to the circular tube. The collection plate inside the collection device is connected to a vacuum connector on the flange cover. The vacuum connector is connected to a data acquisition device via a shielded wire. The data acquisition device includes a current amplifier and an oscilloscope. Shielded wires are used between the vacuum connector and the data acquisition device to prevent electromagnetic interference. A high-voltage connector at the thruster tail is connected to a high-voltage DC power supply outside the vacuum chamber, and the extraction electrode is grounded. The outer shell of this invention is made of metal, and the transmission lines transmitting current signals on the collection plate are wrapped with metal mesh to reduce electromagnetic interference. When the thruster is not launched, the electromagnetic interference image on the oscilloscope is significantly reduced compared to previous solutions.

[0024] 2. The time-of-flight mass spectrometry device for characterizing the performance of electrospray thrusters at different angles disclosed in this invention has an electrostatic gate that is flange-connected to the vacuum chamber outside the vacuum chamber. This allows for the measurement of the plume velocity of the electrospray thruster under limited space conditions, reducing the space requirements of the vacuum chamber and enhancing the temporal resolution of the measurement signal of the time-of-flight mass spectrometry device.

[0025] 3. The time-of-flight mass spectrometry device disclosed in this invention for characterizing the performance of an electrospray thruster at different angles uses recesses on insulating gaskets to fix metal grids, ensuring that the central circular holes of the three metal grids are aligned and that particles can pass through the metal grids to reach the collection plate. The insulating and metal gaskets have evenly distributed circular holes, and the circular tube, insulating gaskets, metal gaskets, and grids are fixed together with bolts. A pulsed high voltage is applied to the middle grid through a high-voltage connector on the circular hole, forming an electrostatic field around it. The central arrangement ensures that the mesh holes are not blocked, guaranteeing that the thruster plume reaches the collection plate normally.

[0026] 4. The time-of-flight mass spectrometry device disclosed in this invention for characterizing the performance of an electrospray thruster at different angles controls the launch angle of the electrospray thruster via an electric rotary table outside the vacuum chamber, thereby achieving precise rotation angle control of the thruster and realizing the measurement of the plume velocity at different angles of the electrospray thruster. This expands the dimensions for measuring the thruster's working performance and can measure the thruster's working capability in different angular directions. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the connections of each part of a TOF device (Time-of-Flight Mass Spectrometer).

[0028] Figures 2(a), 2(b), and 2(c) are internal schematic diagrams of the electrostatic gate device, particle flight tube section, and collection device in the TOF device of the present invention, respectively.

[0029] Figure 3 This is a measurement schematic diagram of a specific embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the collector plate current waveform obtained in positive voltage mode;

[0031] Figure 5 A schematic diagram of the collector plate current waveform obtained under negative voltage mode;

[0032] Figure 6 This is a schematic diagram of the specific impulse (thrust) / launch angle curve of the thruster;

[0033] Figure 7 This is a schematic diagram showing the connection between the TOF device and the vacuum chamber.

[0034] Figure 8 Electromagnetic interference image at the collection plate where a TOF device is not used;

[0035] Figure 9 Use a TOF device to collect electromagnetic interference images at the board;

[0036] Figure 10 This refers to the thruster rotation system in this invention.

[0037] Among them, 1-static gate device, 1a-stainless steel round tube with flange, 1b-insulating gasket, 1c-metal grid, 1d-circular metal gasket, 2-particle flight tube section, 3-collection device, 3a-stainless steel round tube with flange, 3b-insulating gasket, 3c-metal grid, 3d-collection plate, 3e-flange cover plate, 4-TOF device, 5-thruster, 6-power system, 7-data acquisition device, 8-vacuum chamber, 9-thruster system. Detailed Implementation

[0038] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0039] Example 1:

[0040] This embodiment discloses a time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles. The object of measurement is the plume generated by the ion liquid electrospray thruster 5. The external DC power supply has an output range of 0-3500 V, the plume duration is on the order of microseconds, the maximum current can reach tens of microamperes, and the plume path is 600-800 mm. The main components of the plume are charged particles and neutral particles with different velocities.

[0041] like Figure 1 As shown, the time-of-flight mass spectrometry device disclosed in this embodiment for characterizing the performance of an electrospray thruster at different angles includes an electrostatic gate device 1, a particle flight tube section 2, and a collection device 3.

[0042] Figure 2 shows a schematic diagram of the connection relationship between the electrostatic gate device, the particle flight tube section and the collection device in the TOF device.

[0043] The structure of the electrostatic gate device 1 is shown in Figure 2(a), where the flanged stainless steel round tube 1a is welded to the tube. Inside the round tube are insulating gaskets and a metal grid. A circular hole is opened in the wall of the insulating tube, through which a high-voltage connector connects to the metal grid. The front and rear metal grids are grounded. A circular metal gasket is placed in front of the grid, and the central circular hole restricts the plume diffusion angle. In this embodiment, the metal grid is fixed by the recesses on the insulating gaskets, ensuring that the central circular holes of the three metal grids are aligned, allowing particles to pass through the metal grids and reach the collecting plate. The insulating gaskets and metal gaskets have evenly distributed circular holes, and the round tube, insulating gaskets, metal gaskets, and grid are fixed together with bolts. A pulsed high voltage is applied to the central grid through the high-voltage connector on the circular hole, forming an electrostatic field around it.

[0044] The particle flight tube section 2 has flanges at both ends and a circular tube in the middle. The structure of the collection device 3 is shown in Figure 2(c), where the flanged stainless steel circular tube 3a is welded to the flange. Inside the circular tube is an insulating gasket, and in the middle are a metal grid and a collection plate. The metal grid and collection plate are connected to two high-voltage connectors on the flange cover plate by wires. In this embodiment, the metal grid and collection plate are fixed by the recesses on the insulating gasket. There are evenly distributed circular holes on the insulating gasket, and the insulating gasket and grid are fixed together by bolts.

[0045] The electrostatic gate device 1 is fixedly connected to the vacuum chamber 8 and the particle flight tube section 2 via flanges. The circular tube extends into the vacuum chamber. The flanges have four bolt holes, and the three flanges are connected and fixed using bolts and nuts. The collecting device 3 is also fixedly connected to the particle flight tube section via flanges. The high-voltage connector on the electrostatic gate device is connected to the pulse power supply outside the vacuum chamber via a shielded wire. The metal grid is grounded by connecting the circular tube via a wire. The collecting plate inside the collecting device is connected to the vacuum connector on the flange cover. The vacuum connector is connected to the data acquisition device via a shielded wire. The data acquisition device includes a current amplifier and an oscilloscope. Shielded wires are used between the vacuum connector and the data acquisition device to prevent electromagnetic interference. The high-voltage connector at the tail of the thruster is connected to the high-voltage DC power supply outside the vacuum chamber, and the extraction electrode is grounded.

[0046] The principle of Time-of-Flight (TOF) testing is as follows: When no pulsed high voltage is applied to the electrostatic gate, charged particles in the plume generated by the thruster can reach the collecting plate. When a pulsed high voltage is applied, the charged particles cannot pass through the electrostatic gate, but the charged particles that have already passed through at different velocities will reach the collecting plate sequentially, resulting in a current graph that decreases from its maximum value to zero. Figure 4 and Figure 5 As shown, after obtaining the image, the launch mode, thrust and specific impulse of the thruster are obtained according to formulas (4) to (6).

[0047] The principle of variable-angle TOF testing is as follows: the thruster emission angle α is controlled by a rotary table to change the thruster plume emission angle. At this time, a pulsed high voltage is applied to the electrostatic gate so that different charged particles arrive at the collection plate in sequence, resulting in a current image corresponding to different angles where the maximum value decreases to zero. After obtaining the image, the thruster emission mode, thrust, and specific impulse can be obtained according to formulas (4) to (6). By calculating the working plume characteristics of the thruster at different angles, the specific impulse (thrust) / emission angle curve can be fitted with the emission angle as the independent variable and key performance parameters such as specific impulse and thrust as the dependent variable. The working performance of the thruster at different angles can be predicted based on this curve.

[0048] (1)

[0049] Where m, v, and q are the mass, velocity, and charge of the charged particle, respectively, and U is the emission voltage. In the TOF test, the velocity of the charged particle is...

[0050] (2)

[0051] In this context, L represents the distance between the collecting plate and the electrostatic gate, and t represents the time of flight of the charged particle. In the TOF curve, the charge of the charged particle can be obtained by integrating the current I(t).

[0052] (3)

[0053] Where t0 is the initial time of TOF, t TOF Let I(t) be the time it takes for the current signal to drop to zero, and let I(t) be the current in the TOF that changes with time. The mass flow rate of the propellant can be calculated from equations (1) to (3). for

[0054] (4)

[0055] By the momentum theorem And equation (3) yields

[0056] (5)

[0057] In the formula T TOFThis is the thrust calculated from the TOF curve. From the definition of specific impulse, we get...

[0058] (6)

[0059] In this embodiment, an ionic liquid electrospray thruster is selected to verify the basic function of the TOF device. By applying a pulse voltage, current data is collected on the collection plate, and the velocity of the plume generated by the electrospray thruster is measured.

[0060] Figure 7 The basic dimensions of the medium vacuum chamber are 50cm×60cm. TOF experiments are conducted inside this vacuum chamber. A certain distance is required between each device. The internal length is insufficient to accommodate all the devices in the TOF experiment. Therefore, the TOF device 4 needs to be connected to the vacuum chamber through an external flange to conduct the TOF experiment, so that the flight distance reaches 0.8 m and the performance of the ion liquid electrospray thruster is tested.

[0061] Before the formal experimental test, electromagnetic interference signals at the collection board were measured with and without using the TOF device 4, and the oscilloscope images obtained were as follows: Figure 8 and Figure 9 As shown in the image, it can be concluded that using this TOF device can significantly reduce electromagnetic interference.

[0062] The measurement process of the time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles disclosed in this embodiment is as follows: A positive voltage is applied to the electrospray thruster 5 until the electrospray thruster 5 successfully emits a plume and the voltage is stopped when the thruster is in a stable working state. At the same time, the current amplifier in the data acquisition device 7 is turned on and adjusted to an appropriate range. The presence of current on the oscilloscope is observed. Then, a pulse voltage is applied to the electrostatic gate device 1, and the change in the current image on the oscilloscope is observed. After that, the voltage is reduced to zero and switched to a negative voltage. The above steps are repeated.

[0063] The thruster launch angle is controlled by the rotary table in thruster system 9, causing thruster 5 to rotate 5° clockwise. With thruster 5 operating stably, the current amplifier is turned on and adjusted to the L setting with a magnification of 10. 6 Double the current and observe whether there is current on the oscilloscope. At this time, apply a pulse high voltage to the electrostatic gate device 1 and observe the change in the current image on the oscilloscope. Then rotate the thruster 5 clockwise by 5° again and repeat the above steps. The rotation angle of the thruster is in the range of -45° to +45°.

[0064] The time and current data of the collection plate 3d acquired by the data acquisition device 7 are obtained as follows: Figure 4 and Figure 5The image is shown. Based on the formula, and combined with the distance of the plume's flight path, the velocity of charged particles in the plume is obtained. Furthermore, the working thrust and specific impulse of thruster 5 are obtained according to the aforementioned formula. By calculating the working plume characteristics of the thruster at different angles, a specific impulse (thrust) / launch angle curve can be fitted with the launch angle as the independent variable and key performance parameters such as specific impulse and thrust as dependent variables. Based on this curve, the working performance of the thruster at different angles can be predicted, such as... Figure 6 As shown.

[0065] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles, characterized in that, It includes a time-of-flight mass spectrometer, a thruster rotation system, a power supply system, and a data acquisition device; The time-of-flight mass spectrometer includes an electrostatic gate device, a particle flight tube section, and a collection device. The electrostatic gate device is a flanged stainless steel cylindrical tube. Inside the cylindrical tube, there are insulating gaskets, a metal grid, and a circular metal gasket with a central hole. The size of the central hole can change the particle inflow rate. Both ends of the particle flight tube section have flanges. The electrostatic gate device and the particle flight tube section are horizontally connected via flanges. The collection device and the particle flight tube section are horizontally connected via another flange. The collection device is a stainless steel cylindrical tube with a disc flange. Inside the cylindrical tube, there are insulating gaskets, a metal grid, and a collection plate. The thruster rotation system includes a thruster system, an electric rotary table, and a fixing device. The fixing device consists of a transition plate and a Z-axis lifting platform. The thruster system includes an electrospray thruster and a thruster housing. The electric rotary table is connected to an external control system via control lines. The power supply system includes an adjustable high-voltage DC power supply and a high-voltage pulse power supply; The data acquisition device includes a current amplifier and an oscilloscope; The metal grid of the electrostatic gate device is placed on the groove of the insulating gasket, and the notch on the metal grid coincides with the protrusion of the insulating gasket. The metal gasket is located at the tube opening, followed by an insulating gasket and a metal grid, totaling four insulating gaskets and three metal grids. A circular hole is formed in the wall of the circular tube of the electrostatic gate device, through which the high-voltage connector connects to the middle metal grid of the electrostatic gate device. The front and rear metal grids of the electrostatic gate device are grounded. The insulating gasket, metal grid, and metal pad of the electrostatic gate device are tightly fitted and fixed to the circular tube of the electrostatic gate device with bolts. The adapter plate is used to connect and fix the Z-axis lifting platform to the electric rotary platform, and is installed between the electric rotary platform and the Z-axis lifting platform. The electrostatic gate device is fixedly connected to the vacuum chamber and particle flight tube section via a flange, and the circular tube of the electrostatic gate device extends into the vacuum chamber. The high-voltage connector on the electrostatic gate device is connected to the high-voltage pulse power supply outside the vacuum chamber via a shielded wire. The vacuum connector is connected to the data acquisition device via a shielded wire. The collecting device also includes a spring and a flange cover. The collecting plate inside the collecting device is connected to a vacuum connector on the flange cover. The metal grid and the collecting plate are placed on the groove of the insulating gasket, and the notches on the metal grid and the collecting plate coincide with the protrusions of the insulating gasket. The insulating gasket, the metal grid, and the collecting plate are placed sequentially at the pipe opening. The collecting device has three insulating gaskets, one metal grid, and one collecting plate. The metal grid and the collecting plate are connected to two high-voltage connectors on the flange cover via wires. The spring is placed between the disc flange and the last insulating gasket, and contacts both of them. The thruster housing can fix the electro-spray thruster at the center position of the Z-axis lifting platform.

2. The time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles according to claim 1, characterized in that, The electrostatic gate device, particle flight tube section, and collection device have the same flange size and are connected by bolts; the adapter plate has different threaded holes for connecting and fixing the Z-axis lifting platform and the electric rotary table; the thruster housing has screw holes on both sides for fixing the electro-spray thruster at the center position of the Z-axis lifting platform.

3. The time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles according to claim 1, characterized in that, There are sealing rings between the flanges of the electrostatic gate device, the particle flight tube section, and the collection device.

4. The time-of-flight mass spectrometry device for characterizing the performance of an electrospray thruster at different angles according to claim 1, characterized in that, The insulating pad, metal grid, and circular metal pad with a central hole in the electrostatic gate device all have four evenly distributed circular holes for bolt connection.

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