CN116027444B - Suspension power gravity measurement device and method based on electrostatic regulation and control - Google Patents
Suspension power gravity measurement device and method based on electrostatic regulation and control Download PDFInfo
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- CN116027444B CN116027444B CN202310304234.4A CN202310304234A CN116027444B CN 116027444 B CN116027444 B CN 116027444B CN 202310304234 A CN202310304234 A CN 202310304234A CN 116027444 B CN116027444 B CN 116027444B
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Abstract
The invention discloses a suspension power gravity measurement device and method based on electrostatic regulation. A suspension power gravity measurement method based on electrostatic regulation and control is characterized in that an electrostatic field is applied to control the balance position of charged micro-nano particles in a potential well in vibration, so that the vibration center frequency of the micro-nano particles reaches the maximum along with the change of the electrostatic field, the balance of the electrostatic force and self gravity of the micro-nano particles is judged, and then the gravity acceleration is obtained according to the mass, the electric charge quantity and the applied electrostatic field of the micro-nano particles. A suspension power gravity measurement device based on electrostatic regulation comprises micro-nano particles, an electrode, a charge source and a support structure; the support structure is used for supporting the electrode. The invention greatly reduces the complexity of the gravity meter device, is not easily influenced by air molecules, does not need a time sequence control module, and can be widely applied to other static force measurement.
Description
Technical Field
The invention relates to a suspension power gravity measurement device and method based on electrostatic regulation.
Background
The force to which an object is subjected due to the attraction of the earth is called gravity, the magnitude of which is proportional to the mass of the object, and the proportionality coefficient is called gravitational acceleration. As an important parameter characterizing the earth's gravitational field, the gravitational acceleration is not a constant, but a physical quantity that varies dynamically with time and space. The accurate measurement of the gravity acceleration has positive and profound significance for monitoring the change of the local mass distribution of the earth, observing the structure and the motion of the crust, predicting the environmental disasters such as earthquakes, exploring underground resources and accurately measuring physical quantities.
As a means of achieving accurate measurement of gravitational acceleration, the gravimeter has undergone a process from a single stageAnd (5) developing iteration from a pendulum type gravimeter and an FG5 free fall type gravimeter to a cold atom interference gravimeter. The simple pendulum type gravity meter realizes gravity acceleration according to the length l of the simple pendulum and the swinging period T
Factors such as the approximation of a measurement formula, the error of length measurement and the like limit the improvement of the measurement precision. The FG5 free-falling gravity meter can accurately measure the gravity acceleration according to the time t and the distance s of the free falling of the object, and the distance of the free falling can be accurately measured by adopting a laser ranging method. According to the distance and initial speed of free falling body movementv 0 Relation +.>
Fitting the time and distance data of the free falling body, and measuring to obtain the gravitational acceleration. FG5 type free falling gravity meter is very low in data acquisition frequency due to long falling movement time, and is difficult to continuously and repeatedly measure in a short time. In recent years, a gravity meter using cold atoms or micro-nano particles as falling bodies has been rapidly developed, and this disadvantage of FG5 type free falling gravity meters is greatly improved.
Cold atom interferometry gravimeter is based on principle experimental studies of atomic interferometry by effecting measurement of gravitational acceleration in transition of cold atoms in gravitational field [ Zhou Minkang, university of science and technology, 2011]. Specifically, a potential well formed by laser or other electromagnetic fields is utilized to cool and trap an alkali metal atom system, so that an atom fountain moving vertically upwards is prepared. The most common atoms are 87 An Rb atom. Under the action of two laser pulses, cold atoms generate Raman transition from electron ground state
Transition to a particular excited state +.>
. Since the path of the raman transition of the cold atom in the gravitational field is not unique and the phase information carried by the cold atom depends on the path of the transition, it is thereforeInterference occurs between cold atoms which reach the same end state by going through different raman transition paths, the cold atoms being located in the end state +.>
The probability of (2) exhibits an oscillating characteristic with the time delay of the two laser pulses. The phase difference between different Raman transition paths can be measured from the characteristics of the oscillation, and the phase difference between different paths is determined by the gravity acceleration, the phase difference of two laser beams and the time delay, so that the accurate measurement of the gravity acceleration can be realized. The cold atom interferometer greatly improves the data acquisition rate, can realize the resolution of mu Gal magnitude, and is widely applied to engineering application and basic scientific research fields, but the change of the phase difference and time delay of two laser pulses depends on a precise time sequence control module, and the preparation of cold atoms also puts forward extremely high requirements on the vacuum degree of an experiment.
The gravity meter using micro-nano particles as falling bodies has been reported in literature, and the gravity meter controls the free falling body movement of the micro-nano particles by means of the suspension action of an electromagnetic field on the micro-nano particles, so that the time and distance data of the free falling body movement are obtained, and the accurate measurement of the gravity acceleration is finally realized. Taking a suspension power system based on a focusing light beam as an example, under the action of light, the focusing light beam can suspend the micro-nano particles in a vacuum environment, and at the moment, the micro-nano particles vibrate under the combined action of self gravity, light power, air resistance and thermal noise random force, and the displacement, speed and vibration frequency of the micro-nano particles meet certain probability distribution. Air resistance and thermal noise random forces in a vacuum environment are negligible compared to the optical forces and self-gravity forces. If the suspension light beam is removed, the micro-nano particles fall freely under the dominant action of self gravity, and after the position of the micro-nano particles is changed by a certain amount, the suspension light beam is started, the micro-nano particles are suspended in the environment, and vibration is restarted. From this, a series of time and distance data for the free fall of micro-nano particles can be obtained. Based on the principle, a research team of the Federal chemical engineering institute in Zuishi applies a square wave modulation signal to the suspension light beam in experiments, so that the motion state of the suspension micro-nano particles is switched between free fall and vibration, and finally, the motion data of the free fall of the micro-nano particles under the action of self gravity is obtained to realize accurate measurement of the gravity acceleration [ Phys Rev Lett, 121 (2018) 063602 ]. In resolving gravitational acceleration from free-fall motion data, the effect of randomness of the initial velocity of the micronano particles needs to be considered, which increases the complexity of the gravitational acceleration resolving algorithm. As with cold atom interferometers, such a gravimeter requires a precise timing control module. In addition, there is a risk of escape of the micro-nano particles with the suspended beam removed for such a gravimeter.
The existing gravity acceleration measurement technology is mostly based on free falling body movement of an object, and indirectly measures gravity acceleration from time and distance data of the free falling body movement, and has the following defects:
(1) The complexity of the device system is high. For cold atom interferometry, the preparation of cold atoms depends on vacuum levels better than 10 -9 The ultra-high vacuum environment of mbar, and therefore the pump set of the vacuum system of cold atom interferometers often needs to be constituted by a combination of mechanical pumps, molecular pumps, ion pumps, etc. In addition, multiple laser pulses are needed for excitation and detection of Raman transition of cold atoms in a gravitational field, and parameters such as width and intensity of the laser pulses, time delay and phase difference among the laser pulses and the like need to be accurately regulated and controlled; for the gravity meter taking micro-nano particles as falling bodies, a certain control means is required to be introduced into an electromagnetic field suspension experiment system to modulate an electromagnetic field, and the modulator has extremely high response speed, and the characteristics of modulation bandwidth, stability and the like can influence the measurement result of gravitational acceleration.
(2) The influence of air molecules is not excluded. For cold atom interferometers, the residual air molecules in the environment can have an impact on the gravitational acceleration measurements despite the extremely high vacuum. On one hand, the resistance of the residual air molecules to cold atoms can influence the phase difference of cold atom interference, and on the other hand, the collision of the residual air molecules with the cold atoms causes the consumption of the cold atoms, and all factors can restrict the improvement of the sensitivity and the resolution of the gravimeter; likewise, for a gravity meter with micro-nano particles as the falling body, the influence of the damping force of air molecules on the micro-nano particles and the random force of thermal noise on the free falling body movement of the micro-nano particles in the gravity field cannot be completely eliminated.
(3) The complexity of the gravitational acceleration calculation algorithm is high. For a cold atom interferometer gravity, the calculation algorithm of the gravity acceleration depends on quantum transition and path integration theory, so that theoretical formulas between the phase differences of different Raman transition paths of the cold atoms, the gravity acceleration and laser pulse parameters can be obtained. The physical quantity which is directly measured in experiments is Raman transition probability caused by cold atom interference, the phase difference of the Raman transition path of the cold atom is extracted according to the probability, and the phase difference is substituted into the theoretical formula to obtain data of gravitational acceleration; for a gravity meter with micro-nano particles as falling bodies, the random distribution of the initial state of the free falling body motion of the micro-nano particles must be considered in a calculation algorithm of the gravity acceleration. The two gravimeter resolving algorithms have extremely high dependence on a theoretical model, and the complexity of the theoretical model directly determines the complexity of the resolving algorithm.
(4) Measuring gravitational acceleration based on free-falling motion of an object must rely on a sophisticated timing control module. The influence on the time measurement accuracy of free falling motion on the gravity acceleration measurement accuracy is important, so that the gravity meter often needs to rely on a crystal oscillator module and an atomic clock with even higher accuracy to realize the time sequence control of a measurement system.
Disclosure of Invention
In view of the foregoing drawbacks of the gravity measuring device based on free-falling motion of an object, the present invention aims to provide a gravity measuring device and method based on electrostatic regulation and control for a suspension power system, wherein an electrostatic regulation and control means is applied on the basis of the suspension power system, and gravity acceleration is measured without depending on the free-falling motion of the object.
A suspension power gravity measurement method based on electrostatic regulation and control is characterized in that an electrostatic field is applied to control the balance position of charged micro-nano particles in a potential well in vibration, so that the vibration center frequency of the micro-nano particles reaches the maximum along with the change of the electrostatic field, the balance of the electrostatic force and self gravity of the micro-nano particles is judged, and then the gravity acceleration is obtained according to the mass, the electric charge quantity and the applied electrostatic field of the micro-nano particles.
The micro-nano particle charging mode comprises a charge source based on ultraviolet irradiation photoelectric effect through high-voltage glow discharge, an electron source based on thermal emission and a positive charge source based on alpha ray release.
The electrostatic field is applied through a cylindrical electrode structure or a flat electrode structure.
The derivative of the energy distribution of the potential well along the gravity direction is a nonlinear odd function, and the derivative comprises the potential well based on a focused Gaussian beam, a magnetic potential well formed by a plurality of magnetic pole structures and a potential well formed by a plurality of electrode structures.
The method comprises the following steps:
1) Generating a suspended potential well for the micro-nano particles by adopting a focused Gaussian beam;
2) Applying an electrostatic field to control the balance position of the micro-nano particles vibrating in the suspended potential well;
3) Measuring the change of the center frequency of micro-nano particle vibration along with the applied electrostatic field, and observing the change of the balance position;
4) Measuring electrostatic force when the center frequency of micro-nano particle vibration reaches the maximum value along with the change of the electrostatic field;
5) The gravitational acceleration is derived from the mass of the micro-nano particles, the amount of charge, and the applied electrostatic field.
The method comprises the following steps:
2.1 Suspended micro-nano particles): the Gaussian beam forms an optical potential well after being focused, and the action of the optical potential well on the micro-nano particles enables the micro-nano particles to be suspended in the environment;
2.2 Controlling the release and movement of free charge from the charge source to move the free charge to the micro-nano particles, thereby causing the micro-nano particles to carry a net charge;
2.3 Measuring the power spectral density of the motion displacement of the suspended micro-nano particles in a vacuum environment, and fitting the power spectral density by utilizing a Lorentz function to realize the measurement of the mass of the micro-nano particles and the center frequency of vibration of the micro-nano particles;
2.4 Applying an alternating voltage signal to the electrode, accurately measuring the net charge carried by the micro-nano particles according to the response of the micro-nano particles to the alternating voltage signal, and calibrating the electric field intensity of the position of the micro-nano particles;
2.5 Applying a direct voltage to the electrodes to generate an electrostatic field in space, wherein the micro-nano particles carrying a net charge change their equilibrium positions under the action of the electrostatic field; and observing the change rule of the center frequency of the micro-nano particle vibration along with the direct current voltage applied to the electrode, and when the vibration frequency is the maximum value, dividing the measured mass of the micro-nano particle by the electrostatic force born by the micro-nano particle and the gravity of the micro-nano particle to obtain the gravity acceleration.
In the method, step 2.6) measures the net charge carried by the micro-nano particles once every time the direct current voltage is changed in the process of measuring the gravitational acceleration by changing the direct current voltage applied to the electrode in step 2.5), thereby avoiding the influence of fluctuation of the net charge on measurement data.
The suspension power gravity measurement device based on electrostatic regulation adopts the method, and comprises micro-nano particles, electrodes, a charge source and a supporting structure; the support structure is used for supporting the electrode.
The micro-nano particles are particles with diameters in the order of hundreds of nanometers to hundreds of micrometers.
The charge source comprises a charge source based on ultraviolet irradiation photoelectric effect through high-voltage glow discharge, an electron source based on thermal emission and a positive charge source based on alpha ray release.
The invention has the beneficial effects that:
(1) Aiming at the problem of high complexity of the system of the two free-falling type gravity meter devices, the invention greatly reduces the complexity of the gravity meter devices. The invention only needs to apply a pair of electrodes in the vertical direction on the basis of a suspension power system.
(2) The invention solves the problem that the measurement results of the two free-falling type gravimeters are influenced by air molecules based on the measurement principle. The center frequency of the micro-nano particle vibration depends on the first derivative of the combined force applied to the micro-nano particle vibration at the balance position, wherein the balance position is determined by self gravity, electrostatic force and optical power, and the damping force and thermal noise random force of air molecules on the micro-nano particle influence the width and the bottom noise of the power spectral density and do not influence the center frequency of the vibration. Therefore, the direct current voltage applied to the electrode is experimentally changed, and when the center frequency of the micro-nano particles is maximum in the process of changing along with the direct current voltage, the gravity and the electrostatic force of the micro-nano particles are balanced, and the electrostatic force and the mass of the micro-nano particles can be directly measured, so that the gravity acceleration can be measured.
(3) Aiming at the problem that the complexity of the two typical gravimeter resolving algorithms is high, the complexity of the resolving algorithm is greatly reduced. In the invention, the mass of the micro-nano particles can be measured by fitting an experimentally measured power spectrum by using a Lorentz function, and the electrostatic force can be obtained by measuring the net charge quantity and electrostatic field of the micro-nano particles.
(4) Aiming at the problem that the two typical gravimeters have high dependence on a precise time sequence control module, the invention does not need to measure the motion data of the free falling body of the micro-nano particles, but realizes the measurement of the gravity of the micro-nano particles by measuring the electrostatic force under the balance condition of the gravity and the electrostatic force, so the invention does not need a time sequence control module.
(5) The invention can be widely applied to other static force measurement, such as the scattering force of focused light beams on micro-nano particles, and the like.
Drawings
Fig. 1 is a schematic view of a construction of the device of the present invention.
FIG. 2 shows the micro-nano particles in an equilibrium positiony 0 A force analysis schematic diagram.
Fig. 3 is a flow chart of the invention for measuring gravitational acceleration.
Fig. 4 is a schematic view of the structure of an apparatus to which embodiment 1 is applied.
Fig. 5 is a schematic view of an improved structure of an electrode.
Detailed Description
The invention is further illustrated in the following figures and examples.
A schematic diagram of the device structure of the invention is shown in fig. 1; the device consists of micro-nano particles 1, an electrode 2, a charge source 3 and a support structure 4.
The micro-nano particles 1 are particles with diameters of hundred nanometers to hundred micrometers, are not limited in material, can be stably suspended in a vacuum environment under the action of a focusing Gaussian potential well or other potential wells, and are sensitive units for gravity acceleration sensing measurement.
The electrodes 2 are placed along the vertical direction for generating an electric field in the vertical direction. The electrode 2 is used for generating an alternating electric field to achieve calibration of the electric field strength and measurement of the net charge of the micro-nano particles 1, in addition to generating an electrostatic field around the micro-nano particles 1 to change the equilibrium position of the micro-nano particles 1 vibrating. To ensure uniformity of the electric field strength around the micro-nano particles 1, the size of the electrode 2 should be much larger than the micro-nano particles 1. The optimal position of the micro-nano particles 1 should be located in between the two electrodes and not in mechanical contact with the electrode 2.
The charge source 3 needs to controllably generate free charges so that the micro-nano particles 1 carry a certain net charge amount. The calibration of the measurement of the net charge of the micro-nano-particles 1 also depends on the transfer of the free charge of the charge source 3 to the micro-nano-particles 1.
The support structure 4 is used for supporting the electrode 2.
The measuring principle of the invention is as follows:
the micro-nano particles 1 move under the combined action of self gravity, optical power, electrostatic force, thermal noise random force of air molecules and damping force, and are in the vertical directionyIs the equation of motion:
wherein, the liquid crystal display device comprises a liquid crystal display device,mrepresenting the mass of the particles and,grepresenting the acceleration of gravity and,y 0 representing equilibrium position coordinates，QRepresenting the net charge of the micro-nano-particles 1,E static representing the strength of the electrostatic field,
representing the damping rate of the air molecules,F thermal representing the thermal noise random force with a power spectral density of +.>
，k B Is a boltzmann constant,Tis ambient temperature.F opt,y (y) Representing the functional expression of the optical power in the motion range of the micro-nano particles 1 when the light beam is not alongyIn the case of a propagation in the direction,F opt,y (y) Edge proportional to beam intensityyThe directional derivative of the direction, which can be written according to the taylor formula:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the optical powerF opt,y (y) In the equilibrium positiony 0 A derivative thereof. From the equation of motion of the micro-nano particles 1, the equilibrium position coordinates of the micro-nano particles 1 can be knowny 0 Determined by both the optical force gravity and the electrostatic force:
correspondingly, the center frequency of vibration of the micro-nano particles 1f y (y 0 ) Depending on its massmBalance positiony 0 First derivative of optical power
：
Based on the above analysis, the micro-nano particles 1 are in the vertical directionyThe power spectral density of motion can be written as:
wherein, the liquid crystal display device comprises a liquid crystal display device,
representing the impulse function. The result of equation (5) shows that the power spectral density of the micro-nano particle 1 includes two parts: and balance positiony 0 Related zero frequency term->
And->
Centered high frequency term
. From this, it can be seen that the damping force of air molecules on the micro-nano particles 1 affects the width of the high frequency term of the power spectral density, the thermal noise random force of air molecules on the micro-nano particles affects only the background noise of the power spectral density, and the mass of the micro-nano particles 1 can be obtained by fitting the experimentally measured power spectral density according to equation (5)mCenter frequency->
Etc.
For a typical Gaussian beam
In other words, the edge in which the micro-nano particles 1 are receivedyOptical power in the directionF opt,y (y) And the light intensity edgeyThe directional derivatives are proportional, thus the optical power +.>
And its derivatives satisfy the relationship:
then, the center frequency of the micro-nano particle 1 vibration satisfies the relation:
from equation (7), it can be seen that the micro-nano particles 1 balance the positiony 0 The farther from the origin of coordinates, the smaller the center frequency of vibration of the micro-nano particles 1. That is, changing the vertical electrostatic fieldE static Can observe the change of the vibration center frequency of the micro-nano particles 1, and when the center frequency of the vibration center frequency of the micro-nano particles 1 is the maximum value, the balance position of the micro-nano particles 1 is just positioned at the origin of coordinatesy 0 When=0, the optical power
Gravity and electrostatic force of micro-nano particles 1 are balanced by two forces +.>
. Based on the prior means, the charge amount of the micro-nano particles 1QAnd an electrostatic fieldE static Can be measured accurately, then, the gravitational accelerationgAnd then determining.
As shown in fig. 3, a flow of a method for measuring gravity of a suspension power based on electrostatic regulation is as follows:
(1) Suspended micro-nano particles 1: the Gaussian beam forms an optical potential well after being focused, and the action of the optical potential well on the micro-nano particles 1 can enable the micro-nano particles 1 to be suspended in the environment;
(2) Controlling the process of releasing and moving the free charge from the charge source 3 to move the free charge to the micro-nano particles 1, so that the micro-nano particles 1 carry a net charge;
(3) In a vacuum environment, measuring the power spectral density of the motion displacement of the suspended micro-nano particles 1, and fitting the power spectral density by utilizing a Lorentz function, so that the mass of the micro-nano particles 1 and the center frequency of vibration of the micro-nano particles can be measured;
(4) Applying an alternating voltage signal to the electrode 2, accurately measuring the net charge carried by the micro-nano particles 1 according to the response of the micro-nano particles 1 to the alternating voltage signal, and calibrating the electric field intensity of the position where the micro-nano particles 1 are positioned;
(5) A direct voltage is applied to the electrode 2, thereby generating an electrostatic field in space, and the micro-nano particles 1 carrying a net charge change their equilibrium positions under the action of the electrostatic field. Observing the change rule of the center frequency of the micro-nano particle 1 vibration along with the direct current voltage applied to the electrode 2, when the vibration frequency is the maximum value, the electrostatic force born by the micro-nano particle 1 is equal to the gravity of the micro-nano particle, and dividing the mass of the micro-nano particle 1 measured in the step (3) by the gravity acceleration;
(6) In the process of changing the central frequency change of the vibration of the micro-nano particles 1 by the direct-current voltage in the step (5), the net charge quantity carried by the micro-nano particles 1 needs to be measured once every time the direct-current voltage is changed, so that the influence of the fluctuation of the net charge quantity on measurement data is avoided.
Application example 1
Fig. 4 is a schematic view of the structure of an apparatus to which embodiment 1 is applied. FIG. 2 shows the micro-nano particle equilibrium position coordinatesy 0 <Force analysis diagram at 0, letter symbols in fig. 2 represent the magnitude of force, and arrows represent the direction of force; the vertical upward direction is defined as the positive direction of the y-axis, and the point where the micro-nano particles are subjected to zero optical power is the origin.
The micro-nano particles 1 are silicon dioxide spherical particles with the diameter of 300 nm. After focusing a collimated gaussian beam having a wavelength of 1064nm with a lens having a numerical aperture of 0.8, the micro-nano particles 1 can be stably suspended in their focal regions. The electrode 2 is a cylindrical metal electrode with the diameter of 1mm and the length of 1cm, and is connected with a single-pole double-throw switch for switching between direct-current voltage and alternating-current voltage signals. The charge source 3 is a device based on high-voltage glow discharge, specifically, a pair of wires which are closely spaced are placed near the micro-nano particles 1, and under the condition of applying instantaneous high voltage, nearby air molecules are ionized to generate free charges, and the free charges are adsorbed on the micro-nano particles 1 to enable the free charges to carry a certain amount of net charges. The support structure 4 may be a rectangular plastic member with a rectangular hole in the middle for placement of the electrode 2.
In summary, the invention can realize accurate measurement of gravitational acceleration based on a typical suspension power system. Compared with the existing gravity meter based on the free falling body motion data of the object, the gravity meter based on the free falling body motion data of the object has the advantages of being low in device complexity, low in data calculation algorithm complexity, free of influence of air molecules and independent of a time sequence control module.
The key point of the invention is that the measurement of the gravitational acceleration is realized without depending on the free falling motion of the object. According to the invention, the balance position of the micro-nano particle vibration is controlled by applying the electrostatic field, in view of the fact that the change of the balance position can be observed through the change of the vibration center frequency, and then the fact that the electrostatic force and the self gravity of the micro-nano particle reach balance is judged by taking the fact that the change of the vibration center frequency along with the electrostatic field reaches the maximum value as a criterion, and the accurate measurement of the gravity acceleration can be realized by measuring the mass of the micro-nano particle, the charge quantity carried by the micro-nano particle and the electrostatic field based on the prior art.
(1) The invention is applicable to any system for generating a suspension potential well for micro-nano particles based on focusing Gaussian beams;
(2) Controlling the balance position of the micro-nano particles vibrating in the suspended potential well by applying an electrostatic field;
(3) Observing the change of the balance position of the micro-nano particles according to the change of the applied electrostatic field by measuring the center frequency of the micro-nano particles vibration;
(4) Measuring the gravity of the micro-nano particles by measuring the electrostatic force when the central frequency of the micro-nano particle vibration reaches the maximum value along with the change of the electrostatic field;
(5) The change of the center frequency of micro-nano particle vibration along with the electrostatic field is used as a direct observed quantity, so that the influence of air molecules on the gravity acceleration measurement is avoided.
Compared with the existing gravity meter based on the free falling body movement of the object, the gravity meter device has the advantage that the complexity of the gravity meter device is greatly reduced. The invention only needs to add a pair of electrodes on a typical suspension power system, and does not need to carry out extra modulation on the light beam.
Compared with the existing gravity meter based on the free falling body movement of the object, the gravity acceleration calculation method greatly reduces the complexity of the gravity acceleration calculation algorithm. The measurement principle of the invention is based on the change of the balance position of the suspended micro-nano particles under the action of an electrostatic field, and the direct observed quantity is the change rule of the center frequency of the vibration of the suspended micro-nano particles along with the electrostatic field. The electrostatic field is generated by a direct current voltage, and the coordinates of the equilibrium position and the applied direct current voltage value show a one-to-one mapping relation. For a commonly used Gaussian beam, when the center frequency of vibration reaches the maximum along with the change of direct-current voltage, the gravity and electrostatic force of the micro-nano particles are balanced, and accordingly, the measurement of the gravity acceleration can be achieved by combining the measurement of the mass of the micro-nano particles.
Compared with the existing gravity meter based on the free falling body movement of the object, the gravity meter avoids the influence of air molecules on the gravity acceleration measurement result. Through detailed analysis of the measurement principle of the invention, the damping force of the air molecules on the micro-nano particles only affects the line width of the power spectral density of the motion of the micro-nano particles, the thermal noise random force of the air molecules on the micro-nano particles only affects the background noise of the power spectral degree of the micro-nano particles, however, the physical quantity directly measured by the invention is the change of the vibration frequency of the micro-nano particles along with the direct current voltage, so the invention avoids the adverse effect of the air molecules on the measurement result. The advantage of the invention determines that the invention has low requirement on the vacuum degree of the system, thereby reducing the complexity of the vacuum system and getting rid of the dependence on vacuum equipment such as an ion pump, a getter pump and the like.
Compared with the existing gravity meter based on the free falling body movement of the object, the gravity meter based on the free falling body movement of the object gets rid of dependence on a precise time sequence control module. The physical quantity directly measured by the invention is the electrostatic force and the mass of the micro-nano particles when the gravity and the electrostatic force of the micro-nano particles are balanced, and the time and distance data of the free falling motion of the micro-nano particles do not need to be acquired, so that the invention does not need any time sequence control module, and the complexity of the device is further reduced.
The embodiments in the foregoing description may be further combined or replaced, and the embodiments are merely illustrative of the preferred embodiments of the present invention and are not intended to limit the spirit and scope of the present invention, and various changes and modifications made by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention.
For example, the invention may be modified and improved as follows:
(1) The suspension of micro-nano particles can be implemented by other types of potential well systems besides focusing Gaussian beams, such as magnetic potential wells formed by a plurality of magnetic pole structures, electric potential wells formed by a plurality of electrode structures, and the like. The requirement can be satisfied as long as the derivative of the energy distribution of the potential well along the direction of gravity is a nonlinear odd function.
(2) The charge source for causing the micro-nano particles to carry a certain amount of net charge can be selected from a charge source based on ultraviolet irradiation photoelectric effect, an electron source based on thermal emission, a positive charge source based on alpha-ray release, and the like, in addition to the high-voltage glow discharge device mentioned in application example 1.
(3) The movement from the free charge from the charge source to the micro-nano particles can be regulated by additional means. For example, an additional electrostatic field is applied to control the movement direction of free charge, and an additional aperture is arranged to control the free charge quantity moving to the micro-nano particles, so that the regulation and control of the net charge quantity carried by the micro-nano particles are realized.
(4) The electrode for applying the electric field may be other types of structures besides the cylindrical electrode structure mentioned in example 1, such as a flat electrode structure or a modified structure as shown in fig. 5, in which a plurality of metal sheets are applied between two cylindrical electrodes in fig. 5, and adjacent two metal sheets are connected by a voltage dividing resistor, which can maximally secure uniformity of the electric field in the space region between the electrodes.
(5) The support structure may be of other types, such as may be integrated with the charge source as a unitary structure.
The above examples merely represent a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of the invention should be assessed as that of the appended claims.
Claims (9)
1. The method is characterized in that the balance position of the vibration of the charged micro-nano particles in a potential well is controlled by applying an electrostatic field, so that the vibration center frequency of the micro-nano particles reaches the maximum value along with the change of the electrostatic field, the balance of the electrostatic force and self gravity of the micro-nano particles is judged, and then the gravity acceleration is obtained according to the mass, the electric charge quantity and the applied electrostatic field of the micro-nano particles;
the derivative of the energy distribution of the potential well along the gravity direction is a nonlinear odd function, and the derivative comprises the potential well based on a focused Gaussian beam, a magnetic potential well formed by a plurality of magnetic pole structures and a potential well formed by a plurality of electrode structures.
2. The method of claim 1, wherein the micro-nano particles are charged by a high-voltage glow discharge based on a charge source of ultraviolet irradiation photoelectric effect, a heat emission based electron source, and an alpha-ray release based positive charge source.
3. The method of claim 1, wherein the electrostatic field is applied by a cylindrical electrode structure or a flat electrode structure.
4. The method according to claim 1, characterized by the steps of:
1) Generating a suspended potential well for the micro-nano particles by adopting a focused Gaussian beam;
2) Applying an electrostatic field to control the balance position of the micro-nano particles vibrating in the suspended potential well;
3) Measuring the change of the center frequency of micro-nano particle vibration along with the applied electrostatic field, and observing the change of the balance position;
4) Measuring electrostatic force when the center frequency of micro-nano particle vibration reaches the maximum value along with the change of the electrostatic field;
5) The gravitational acceleration is derived from the mass of the micro-nano particles, the amount of charge, and the applied electrostatic field.
5. The method according to claim 4, characterized by the steps of:
2.1 Suspended micro-nano particles): the Gaussian beam forms an optical potential well after being focused, and the action of the optical potential well on the micro-nano particles enables the micro-nano particles to be suspended in the environment;
2.2 Controlling the release and movement of free charge from the charge source to move the free charge to the micro-nano particles, thereby causing the micro-nano particles to carry a net charge;
2.3 Measuring the power spectral density of the motion displacement of the suspended micro-nano particles in a vacuum environment, and fitting the power spectral density by utilizing a Lorentz function to realize the measurement of the mass of the micro-nano particles and the center frequency of vibration of the micro-nano particles;
2.4 Applying an alternating voltage signal to the electrode, accurately measuring the net charge carried by the micro-nano particles according to the response of the micro-nano particles to the alternating voltage signal, and calibrating the electric field intensity of the position of the micro-nano particles;
2.5 Applying a direct voltage to the electrodes to generate an electrostatic field in space, wherein the micro-nano particles carrying a net charge change their equilibrium positions under the action of the electrostatic field; and observing the change rule of the center frequency of the micro-nano particle vibration along with the direct current voltage applied to the electrode, and when the vibration frequency is the maximum value, dividing the measured mass of the micro-nano particle by the electrostatic force born by the micro-nano particle and the gravity of the micro-nano particle to obtain the gravity acceleration.
6. The method of claim 5, wherein step 2.6) measures the net charge carried by the micro-nano particles each time the magnitude of the dc voltage is changed during the step 2.5) of changing the dc voltage applied to the electrodes to measure the gravitational acceleration.
7. A suspended optical force gravity measurement device based on electrostatic regulation, characterized in that the method according to claim 1 is adopted, comprising micro-nano particles, electrodes, a charge source and a support structure; the support structure is used for supporting the electrode.
8. The device of claim 7, wherein the micro-nano particles are particles having diameters on the order of hundred nanometers to hundred micrometers.
9. The apparatus of claim 7, wherein the charge source comprises a charge source based on ultraviolet irradiation photoelectric effect by high voltage glow discharge, an electron source based on thermal emission, and a positive charge source based on alpha ray release.
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