CN209896025U - Multi-grid ion energy analysis instrument and probe thereof - Google Patents
Multi-grid ion energy analysis instrument and probe thereof Download PDFInfo
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- CN209896025U CN209896025U CN201921125490.2U CN201921125490U CN209896025U CN 209896025 U CN209896025 U CN 209896025U CN 201921125490 U CN201921125490 U CN 201921125490U CN 209896025 U CN209896025 U CN 209896025U
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Abstract
The utility model discloses a many bars ion energy analysis instrument and probe thereof sets up the mesh aperture of the grid of probe is less than the twice debye radius, just the mesh aperture does in the grid 10-15 times of the net silk diameter of grid. The grid is woven by conductor wires, the potential of the center of a mesh is lower than the potential of the wires, a transverse electric field can be generated, the effect is more obvious when the mesh is larger, the aperture of the mesh of the grid of the probe is smaller than the twice Debye radius due to the Debye shielding effect of plasma, and the aperture of the mesh in the grid is 10-15 times of the diameter of the wires of the grid so that the mesh of the grid is small and dense, and the influence of the transverse electric field can be effectively reduced while the transmittance is ensured.
Description
Technical Field
The utility model relates to a plasma measures the field, and more specifically says, relates to a multi-grid ion energy analysis instrument and probe thereof.
Background
Ion Energy Analyzers (IEAs), also known as retardation analyzers (RPAs), are widely used in ionospheric exploration satellites as an important tool for detecting plasma Energy in situ. However, under the influence of factors such as electric field distortion, plasma sheath, ion temperature and installation manner, the measurement accuracy of the conventional ion energy analyzer is not high, so how to improve the measurement accuracy of the ion energy analyzer is a problem to be solved urgently in the field of plasma measurement.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem, the embodiment of the utility model provides a many bars ion energy analysis instrument and probe thereof is provided, through setting up the aperture and the mesh density of grid in the probe have effectively improved many bars ion energy analysis instrument's measurement accuracy.
In order to achieve the above object, the present invention provides the following solutions:
a probe of a multi-grid ion energy analysis instrument, the probe comprising:
the two ends of the sleeve are respectively covered with a baffle plate and a bottom plate; the baffle plate is provided with a probe opening for passing ions to be detected;
a collector located within the sleeve;
a plurality of layers of grids positioned within said sleeve, said grids positioned between said collector and said baffle, said grids configured to form a selective electric field such that ions above the energy of the electric field are incident on said collector;
wherein the aperture of the meshes of the grid is less than twice the Debye radius, and the aperture of the meshes in the grid is 10-15 times of the diameter of the meshes of the grid.
Preferably, in the probe, insulating spacers are disposed between the baffle and the adjacent grid, between the collector and the adjacent grid, and between the bottom plate and the collector.
Preferably, in the probe described above, the insulating spacer is a ring having an outer diameter equal to an inner diameter of the sleeve.
Preferably, in the probe, a circular groove coaxial with the circular ring is formed on the upper surface of the circular ring;
the baffle is arranged in a groove below the baffle and adjacent to the insulating gasket;
the grid mesh is arranged in a groove below the grid mesh and adjacent to the insulating gasket;
the collector is arranged in a groove below the collector and adjacent to the insulating gasket.
Preferably, in the probe, the base plate, the collector, and the ring have positioning screw holes disposed opposite to each other.
Preferably, in the probe described above, the insulating spacer is a polytetrafluoroethylene spacer.
Preferably, in the probe described above, the magnetic permeability of the sleeve, the baffle, the bottom plate, the collector, and the grid is not more than 1.1.
Preferably, in the above probe, the radius of the probe opening is not less than 1.06mm and not more than 10 mm.
Preferably, in the above probe, the radius of the sleeve is not less than 34.2mm and not more than 100 mm.
Preferably, in the probe, the grid has a conductivity of not less than 106S/m；
The hardness of the grid mesh is not less than 37 HRC;
the expansion coefficient of the grid is not more than 18.2m/m ℃ (at20-100 ℃);
the transmittance of the grid mesh is not less than 80%;
the meshes of the grid mesh are regular hexagonal through holes;
the distance between the adjacent grids is 4mm-7 mm.
The utility model also provides a many bars ion energy analysis instrument, include: the probe of any one of the above.
According to the above description, the technical solution of the present invention is to provide a multi-grid ion energy analyzer and a probe thereof, wherein the mesh aperture of the grid of the probe is smaller than the twice debye radius, and the mesh aperture of the grid is 10-15 times the diameter of the mesh wire of the grid. The grid is woven by conductor wires, the potential of the center of a mesh is lower than the potential of the wires, a transverse electric field can be generated, the effect is more obvious when the mesh is larger, the aperture of the mesh of the grid of the probe is smaller than the twice Debye radius due to the Debye shielding effect of plasma, and the aperture of the mesh in the grid is 10-15 times of the diameter of the wires of the grid so that the mesh of the grid is small and dense, and the influence of the transverse electric field can be effectively reduced while the transmittance is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic view of an internal structure of an ion energy analyzer;
FIG. 2 is a graph of measurements taken by an ion energy analyzer;
fig. 3 is a schematic structural diagram of a probe of a multi-grid ion energy analysis instrument according to an embodiment of the present invention;
FIG. 4 is a schematic view of the sleeve of the probe of FIG. 3;
FIG. 5 is a cross-sectional view of the probe of FIG. 3 taken perpendicular to the axis of the sleeve;
FIG. 6 is a schematic diagram of the construction of a baffle in the probe of FIG. 3;
FIG. 7 is a schematic diagram of the structure of the grid in the probe of FIG. 3;
FIG. 8 is a schematic view of the structure of the dielectric spacer in the probe of FIG. 3;
FIG. 9 is a schematic view of the collector structure of the probe of FIG. 3;
FIG. 10 is a schematic view of the construction of the backing plate in the probe of FIG. 3;
FIG. 11 is a schematic view of a probe profile;
fig. 12 is a schematic view illustrating a grid aligning method according to an embodiment of the present invention;
FIG. 13 is a graph comparing the ion transmission rates of a grid of square mesh and a grid of regular hexagonal mesh;
fig. 14 is a graph comparing ion permeability curves for both aligned and misaligned conditions.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As described in the background art, the measurement accuracy of the conventional ion energy analysis apparatus is not high, and the ion energy analysis apparatus is yet to be further improved.
Ion energy analysis instrument can divide into probe and measuring circuit two parts, and the probe is used for acquireing weak electric current, and measuring circuit is used for detecting weak electric current, the embodiment of the utility model provides a the scheme is mainly through the design of optimizing the probe to improve ion energy analysis instrument's measurement accuracy.
The internal structure of the conventional probe is shown in fig. 1, and fig. 1 is a schematic diagram of the internal structure of an ion energy analyzer, and the probe comprises four layers of grids G1-G4 and a collector C. External ions enter the instrument through the grid G1, and the grid G1 is connected with the instrument ground to shield the external ions from the influence of the internally applied voltage. After the ions enter the instrument, they encounter two layers of blocking grids G2 and G3. The blocking grid is applied with positive scanning voltage to form an electric field, ions with different energies are screened by the electric field, and only the ions with the energy higher than the electric field can reach the grid G4 through the two layers of blocking grids G2 and G3. The grid G4 is negatively biased with respect to the instrument ground to prevent electrons flying in from reaching the collector C and also to suppress the escape of secondary electrons excited by energetic ions from the collector C. The ions passing through the grid G4 eventually reach the collector C to form a current. The first differential of the current versus scan voltage curve is the ion energy distribution, the measurement result is shown in fig. 2, fig. 2 is the measurement curve of the ion energy analyzer, the horizontal axis is the voltage V, and the vertical axis is the current I.
In the existing ion energy analysis instrument, the measurement of high-energy density ion energy in a plasma material is mainly aimed at, and under the condition, a signal to be measured is strong and is relatively easy to measure. However, when the ion energy is low, such as the magnitude of eV as the present invention focuses on, the measurement current is in the magnitude of pA, and the measurement signal is not obtained by this measurement method due to the low measurement accuracy.
In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description.
Referring to fig. 3 to 9, fig. 3 is a schematic structural diagram of a probe of a multi-grid ion energy analyzer according to an embodiment of the present invention, fig. 4 is a schematic structural diagram of a sleeve in the probe shown in fig. 3, fig. 5 is a sectional view of the probe shown in fig. 3, the sectional view being perpendicular to an axis of the sleeve, fig. 6 is a schematic structural diagram of a baffle in the probe shown in fig. 3, fig. 7 is a schematic structural diagram of a grid in the probe shown in fig. 3, fig. 8 is a schematic structural diagram of an insulating spacer in the probe shown in fig. 3, fig. 9 is a schematic structural diagram of a collector in the probe shown in fig. 3, and fig. 10 is a schematic structural diagram of a bottom plate. The grid 22 and the collector 23 are energized by means of electrode plates, not shown in the drawings, connected to their respective surfaces.
The probe includes: the sleeve 24, both ends of said sleeve 24 are covered with the baffle 21 and bottom plate 26 separately; a collector 23 located within a sleeve 24; a plurality of layers of mesh 22 positioned within said sleeve 24, said mesh 22 being positioned between said collector 23 and said baffle 21, said mesh 22 being configured to create an electric field selected such that ions of higher energy than the electric field are incident on said collector 23; wherein the baffle 21 has a probe opening 20 for passing ions to be detected; the aperture of the meshes of the grid 22 is smaller than twice the Debye radius, and the aperture of the meshes in the grid 22 is 10-15 times of the diameter of the mesh wires of the grid. For ease of illustration, a schematic partial cross-section of the sidewall of the sleeve 24 is shown in fig. 3, with the actual sidewall of the sleeve 24 being a complete cylinder.
Because the aperture of the meshes of the grid net 22 of the probe is smaller than the Debye radius which is two times, and the aperture of the meshes in the grid net 22 is 10-15 times of the diameter of the mesh wires of the grid net, the meshes of the grid net 22 are small and dense, the effectiveness of a vertical electric field of the grid net 22 can be ensured, and the influence of a transverse electric field can be effectively reduced while the transmittance is ensured.
The sleeve 24 is configured as shown in fig. 4, and the sleeve 24 is a cylindrical structure. Each part in the cylinder is provided with a preset positioning screw hole 31 so as to be mutually fixed through the preset positioning screw holes 31.
The number of grids 22 can be set as multiple layers based on the requirements, with the top grid grounded and the bottom grid biased negatively with respect to the instrument ground. The grids between the top and bottom grids are used to form the selection electric field.
In the embodiment of the present invention, four layers of grids 22 are provided, and the four layers of grids 22 are sequentially a top grid 221, a bottom grid 224, and two blocking grids 222 and 223 between the top grid 221 and the bottom grid 224. The top grid 221 is grounded to shield the influence of the voltage applied to the middle two blocking grids 222 and 223 on external ions, the middle two blocking grids 222 and 223 apply scanning voltage, an electric field is formed between the two blocking grids 222 and 223, ions with different energies are screened through the electric field between the two blocking grids 222 and 223, and only ions with energy higher than the electric field can reach the bottom grid 224 through the two blocking grids 222 and 223. The bottom grid 224 is negatively biased with respect to the instrument ground to prevent front-end-flying electrons from reaching the collector 23, while suppressing escape of secondary electrons from the collector 23 excited by energetic ions. Ions passing through the bottom grid 224 are eventually detected by the collector 23 to form a current.
The grid 22, the baffle 21, the collector 23 and the bottom plate 26 are all conductors, and in order to avoid short circuit, in the sleeve 24, two adjacent parts in the axial direction need to be insulated, so that insulating gaskets 25 are arranged between the baffle 21 and the adjacent grid 22, between the collector 23 and the adjacent grid 22, and between the bottom plate 26 and the collector 23.
Each insulating spacer 25, each grid 22, the baffle 21, the collector 23 and the bottom plate 26 are provided with positioning screw holes 31 which are arranged oppositely, and alignment and fixation among all the parts are realized through screws in the positioning screw holes 31. The number of the positioning screw holes 31 on each part is the same and the positioning screw holes are arranged opposite to each other. The number of the positioning screw holes 31 on the same component can be set to be any number based on the requirement, and is not limited to 6 in the embodiment of the present invention.
As shown in fig. 5, the sleeve 24 has a baffle 21, a first insulating pad 251, a top grid 221, a second insulating pad 252, a blocking grid 222, a third insulating pad 253, a blocking grid 223, a fourth insulating pad 254, a bottom grid 224, a fifth insulating pad 255, a collector 23, a sixth insulating pad 256, and a bottom plate 26 from top to bottom.
The embodiment of the present invention provides a mode of realizing insulation of two adjacent conductive parts in the sleeve 24 is not limited to a mode of passing through the insulating spacer 25, and in other modes, the mode of passing through the insulating gap or the insulating pillar disposed between the peripheries of the two parts can also be used.
As shown in fig. 7, the grid 22 is fixed to a ring-shaped support member 41, and the positioning screw holes 31 of the grid 22 pass through the ring-shaped support member 41. The loop support members 41 serve to maintain the grid 22 in a better flat deployment.
As shown in fig. 8, the insulating spacer 25 is a circular ring having an outer diameter equal to the inner diameter of the sleeve 24. The upper surface of the ring is provided with a circular groove 251 coaxial with said ring to facilitate the mounting and fixation of the components above the insulating gasket 25 in the insulating gasket 25. As shown in fig. 5, the baffle 21 is disposed in the groove 251 of the adjacent insulating spacer 25 therebelow; the grid 22 is arranged in the groove 251 of the adjacent insulating gasket 25 below the grid; the collector 23 is placed in a recess 251 below and adjacent to the insulating spacer 25. The bottom plate 26, the collector 23 and the ring 31 have oppositely arranged positioning screw holes.
As shown in fig. 5 and 10, the base plate 26 is provided with a signal line hole 260 for leading out a signal line to which each component is connected.
The embodiment of the utility model provides a probe is used for ion energy analysis instrument, and this probe has a plurality of grids 22, can be used for founding many bars ion energy analysis instrument, through improving the probe structure to improve the measurement accuracy of probe, and then can improve the measurement accuracy of the many bars ion energy analysis instrument of founding, need not to improve measuring circuit.
To the problem that current probe measurement accuracy is not high, the embodiment of the utility model provides a probe improves probe structure from following ten aspects, based on these ten design principles, the structure of each part in the design probe, select processing method and material, can be convenient, the efficient carries out the design and the preparation of high accuracy probe, this ten design principles all can improve probe measurement accuracy to a certain extent, can be through one or a plurality of improvement probes in these ten design principles, in order to improve its measurement accuracy, and then improve the measurement accuracy of whole multi-grid ion energy analysis instrument.
First, the conductive features of the probe are provided with low magnetic properties. Under the action of the magnetic field, the moving direction of the charged particles can be changed, so that the ion transmittance is changed. The conductive elements should have low magnetic properties to reduce or prevent ions entering the probe from being affected by the magnetic field. Based on this, the permeability of the sleeve 24, the baffle plate 21, the bottom plate 26, the collector 23, and the grid 22 is set to be not more than 1.1. The probe adopts a stainless steel sleeve 24, a stainless steel baffle plate 21, a stainless steel bottom plate 26, a stainless steel collector 23 and a stainless steel grid 22. The conductive parts are made of stainless steel material, preferably 06Cr19Ni10 austenitic stainless steel (304 stainless steel), which is a nonmagnetic material with a typical value of relative permeability of 1.05-1.1.
Secondly, the size of the probe opening 20 on the baffle 21 is designed according to the weak current measurement accuracy. If the radius of the probe opening 20 is too large, the voltage inside the probe will disturb external ions, and if the radius of the probe opening 20 is too small, the induced current of the collector 23 will be reduced, and the difficulty of weak current measurement will be increased. The probe can be used for ionosphere detection of plasma in the orbital region of a satellite or equivalentMeasuring plasma parameters with a Debye length of 2.37-1140.41mm and an ion density of 1 × 104-2×106atom/cm3In consideration of the extreme temperature of 5000K, the maximum ionothermal velocity is 9.1km/s, the weak current measurement accuracy is 20pA, and the ionosphere probe satellite velocity is 700m/s, based on which the radius r of the probe opening 20 is set to be not less than 1.06mm and not more than 10mm, and preferably set to be 5 mm. The radius r of the probe opening 20 is within the value range, so that the voltage inside the probe can be effectively prevented from disturbing external ions, and the collector 23 can better induce weak current.
Third, the inner radius R of the sleeve 24 is designed according to the external ion motion. The inner diameter of the sleeve 24 is set to be R, the height is set to be H, and the radius of the probe opening 20 of the baffle 21 at the top of the sleeve 24 is set to be R. Because the ion can not be ensured to vertically enter the probe, the ion entering the probe at the velocity V is obliquely incident and has a certain transverse velocity VyAnd a certain vertical velocity VzFIG. 11 is a schematic view of the probe profile, as shown in FIG. 11, with the lateral velocity VyThermal velocity V comprising ionsthyAnd a lateral component V of the ion drift velocitydy. The vertical velocity VzIs equal to Vz0With vertical component V of ion drift velocitydz。Vz0For testing the speed of the platform where the probe is located, if a general ion energy tester is placed on an ionosphere detection satellite for ion energy detection, at the moment, Vz0The satellite velocity is detected for the ionosphere. If R is too small, ions may strike the side wall of the sleeve 24 before entering the probe and reaching the collector 23, which would affect the external plasma if R is too large, since the probe is typically exposed to the plasma space. The probe can be used for measuring plasma parameters in an ionosphere exploration satellite orbit region or equivalent plasma parameters, wherein the Debye length is between 2.37 and 1140.41mm, and the ion density is 1 x 104-2×106atom/cm3Considering that the maximum ion thermal velocity is 9.1km/s, the weak current measurement precision is 20pA and the ionosphere detection satellite velocity is 700m/s at the extreme temperature of 5000KTherefore, the embodiment of the present invention provides that the radius R of the sleeve 24 is not less than 34.2mm, and is not more than 100mm, and preferably can be 40 mm. The radius R of the sleeve 24 is within this value range, which can ensure that more obliquely incident ions reach the collector 23 as far as possible, and avoid the large influence of the overlarge radius R of the sleeve 24 on the external plasma. Wherein the transverse direction is a direction perpendicular to the axis of the sleeve 24 and the vertical direction is a direction parallel to the axis of the sleeve 24.
Fourth, a grid 22 of high conductivity is used. The metal electrode plates extruded on the periphery of the grid net 22 apply set voltage to the grid net 22, the grid net 22 with high conductivity can ensure that the plane of the grid net 22 is in an equipotential state, and further the measurement accuracy can be improved. Based on this, the conductivity of the grid 22 is not less than 106S/m, the larger the grid conductivity, the better.
Fifth, a mechanically strong grid 22 is used. The grid 22 is fixed inside the probe through the extrusion of the insulating gasket 25 and the screws in the positioning screw holes 31, and the grid 22 with strong mechanical property can be kept flat when being extruded. At the same time, the grid 22 should have a small expansion coefficient to avoid distortion due to changes in ambient temperature. Based on this, the rigidity of the grid 22 is set to not less than 37HRC, the larger the rigidity is, the better, and the expansion coefficient of the grid 22 is set to not more than 18.2 mm/DEG C (at20-100 ℃), the smaller the expansion coefficient is, the better.
Sixth, a high transmittance grid 22 is used. Collector 23 current is typically on the order of pA and is already difficult to detect. Due to the existence of the mesh wires of the grid mesh 22, when ions pass through each layer of grid mesh 22, the flux is attenuated, so that the current of the collector 23 is smaller, and the difficulty of detecting weak current by a detection circuit is increased. The current induced by the collector 23 can be increased by increasing the transmittance of the grid 22, so that the weak current is ensured to be in a measurable range. Based on this, the transmittance of the grid 22 is set to not less than 80%. The transmittance is the percentage of the total area occupied by the mesh of the grid 22.
Seventh, a grid 22 with smaller mesh openings and a dense mesh openings is used, with the mesh openings having a diameter less than twice the debye radius. The potential at the center of the mesh is necessarily lower than the potential of the mesh wires, and a transverse electric field is generated. The larger the mesh, the more pronounced the effect. To ensure the effectiveness of the electric field of the grid 22 due to the debye shielding effect of the plasma, the aperture of the grid 22 should be less than twice the radius of the debye.
Eighth, the meshes of the grid 22 are regular hexagons. Compared with square meshes or meshes in other shapes, the regular hexagonal meshes have smaller area and fewer meshes and have smaller probability of ions colliding with the meshes under the condition of certain transmittance. Based on this, the mesh holes of the grid 22 are arranged to be regular hexagonal through holes.
Ninth, the spacing between the grids 22 is set reasonably. If the distance between the grids 22 is too large, the probe volume is too large, the external plasma is affected, and if the distance between the grids 22 is too small, the large electric field distortion is generated, and the measurement result is affected. Based on this, for ions with measurement energy in the order of eV, the spacing between adjacent grids is set to be 4mm to 7 mm.
Tenth, the grid 22 is placed in strict alignment. As shown in fig. 12, fig. 12 is a schematic view illustrating the alignment of the grids according to the embodiment of the present invention, the left view of fig. 12 is a partial enlarged view of two grids 22a and 22b in the aligned state, and the right view of fig. 12 is a partial enlarged view of two grids 22a and 22b in the unaligned state, if the two grids 22 are in the unaligned state, the ions will have a higher probability to pass through the previous grid 22b and then the grid 22a in the next layer, and further the induced current of the collector 23 will be reduced. Furthermore, the ion permeability curve of the misaligned grid 22 deviates significantly from the step function form, which can introduce large measurement errors. Based on this, all the grids 22 are arranged to be identical and strictly aligned.
Because the ion energy to be measured is lower, in the magnitude of eV, the existing stable ion source with low energy generated on the ground is difficult to perform, so that the performance of the instrument cannot be quantitatively tested through an experiment, and the performance of the probe can be subjected to simulation test through simulation software COMSOL.
The sixth design principle described above requires the use of a high transmittance grid 22. Table 1 below shows common 100 meshes, 200 meshes and 400 meshes grid aperture LUT, through calculating, the transmissivity ratio of these grids is lower, only about 35%, shows that the transmissivity of conventional grid is unsuitable as the grid of probe, needs to be based on the utility model relates to a principle, the preparation accords with the utility model discloses the high transmissivity's of demand grid.
TABLE 1
Theoretically, the closer the ion transmittance curve of the probe is to the ideal step function, the smaller the measurement error is. The eighth design principle requires the use of regular hexagonal mesh openings, as shown in fig. 13, fig. 13 is a graph comparing the ion transmittances of the grid with square mesh openings and the grid with regular hexagonal mesh openings, as shown in fig. 13, it can be seen that the transmittance curve of the grid with regular hexagonal mesh openings is closer to a step function.
The tenth design principle requires strict alignment of the grid mesh, as shown in fig. 14, fig. 14 is a comparison graph of ion transmittance curves in both aligned and misaligned states, as shown in fig. 14, the transmittance curve in the misaligned state deviates from the step function seriously, which results in a large measurement error.
Table 2 below lists the measurement results of ion energy distribution at different ion temperatures in simulated ionosphere probe satellite orbit environment, and it can be seen that the maximum relative error of the ion mean velocity is 2.77%, and the maximum root mean square error of the ion energy distribution is 0.73 eV. It is shown that although electric field distortion, plasma sheath and ion temperature may have an effect on the measurement results, the effect is small, especially when the ion temperature is low.
TABLE 2
| temperature/K | Mean velocity/(m/s) | Relative error/%) | Root mean square error/eV |
| 500 | 7593 | -0.09 | 0.05 |
| 1000 | 7626 | 0.34 | 0.11 |
| 1500 | 7657 | 0.75 | 0.07 |
| 2000 | 7811 | 2.77 | 0.73 |
Can know through the above-mentioned description, adopt the embodiment of the utility model discloses the ion transmittance curve of the probe that the scheme relates to more is close the step function of ideal, and measuring error is less, measurement ion energy distribution that can be comparatively accurate.
Ion parameters under the ionosphere based on survey satellite orbit environment below and the utility model discloses the design principle of probe explains the concrete implementation of probe.
In a first step, the materials of the various components are determined.
The 304 stainless steel is one of stainless steels which is oxidation resistant, has high mechanical strength and no magnetism, satisfies the first and fifth principles, and is an ideal material for the sleeve 24, the baffle plate 21, the bottom plate 26 and the grid 23. The poly (tetrachloroethylene) has excellent insulating properties, allows rapid cooling and heating, is slightly elastic, and can be used as a processing material for the insulating spacer 25, so that the insulating spacer 25 is a poly (tetrachloroethylene) spacer.
And secondly, determining the processing mode of each part.
The sleeve 24, the stop plate 21 and the base plate 26 may be machined using conventional lathes, while the grid 22 is a precision part of the probe, which cannot meet the requirements for precision. The grid 22 is fabricated using a photolithographic process. The precision of the photolithography process is high, within 1 μm, and it can ensure high consistency of each grid 22. Also, since the photolithography process requires that the metal sheet used for processing be smooth and flat, it is ensured that each grid 22 is completely flat.
And thirdly, determining the sizes of all parts.
The Debye length in the ionosphere exploration satellite orbit region is between 2.37mm-110.41mm, the seventh design principle requires the grid mesh to be small and dense and the aperture to be less than twice the Debye radius, and the grid mesh can be 1 mm. The sixth design principle requires that the transmittance of the grid 22 is as high as possible, the diameter of the mesh can be 0.1mm, and the thickness can be 0.1 mm. In this case, the transmittance of the grid 22 is (1/1.1)2＝82.64％。
Ionospheric probe satellite velocity Vz0About 7600m/s, and an ion density in the region of the track in the range of 1X 104atom/cm-3-2×106atom/cm-3. The weak current detection accuracy was assumed to be 1pA, with a noise level of 0.1 pA. At the low end of the ion density measurement index (i.e., ion density N10)4atom/cm-3) The measured ionic current was not lower than 20pA calculated as 5% relative error, i.e.:
qAχNvz0＝1.6×10-19×3.14×r2×(82.64％)2×104×7600≥20pA
wherein q is the unit charge amount, A is the area of the probe opening 20 on the baffle 21, and χ is the transmittance.
As shown in FIG. 11, if the grid 22 spacing is 4mm, the height H is about 20mm, considering that the more extreme ion temperature is 5000K, the hydrogen ions H+Has a thermal velocity of 9.1km/s and a nitrogen ion He+Has a thermal velocity of 4.5km/s and a cation of O+Is 2.3km/s, while considering the more extreme lateral component Vdy of ion drift velocity to be 2km/s, the field of view of the ion energy analyzer sensor is required to satisfy:
arctan(H/(R-r))≤arctan(7.60/(9.1+2))
therefore, R.gtoreq.34.2 mm, preferably 40mm, can be obtained.
And fourthly, mounting.
The baffle 21, the first insulating gasket 251, the top grid 221, the second insulating gasket 252, the blocking grid 222, the third insulating gasket 253, the blocking grid 223, the fourth insulating gasket 254, the bottom grid 224, the fifth insulating gasket 255, the collector 23, the sixth insulating gasket 256 and the bottom plate 26 are sequentially arranged from top to bottom according to the sleeve 24, and are sequentially arranged from top to bottom or from bottom to top. The screws in the positioning screw holes 31 hold the various components together while ensuring proper alignment of the grid 22.
Based on the above embodiment, the utility model discloses another embodiment still provides a multi-grid ion energy analysis instrument, and this multi-grid ion energy analysis instrument includes above-mentioned embodiment the probe has higher measurement accuracy.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the multi-grid ion energy analysis instrument disclosed by the embodiment, the description is relatively simple because the multi-grid ion energy analysis instrument corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the corresponding parts of the probe for description.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in an article or device that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A probe of a multi-grid ion energy analysis instrument, the probe comprising:
the two ends of the sleeve are respectively covered with a baffle plate and a bottom plate; the baffle plate is provided with a probe opening for passing ions to be detected;
a collector located within the sleeve;
a plurality of layers of grids positioned within said sleeve, said grids positioned between said collector and said baffle, said grids configured to form a selective electric field such that ions above the energy of the electric field are incident on said collector;
wherein the aperture of the meshes of the grid is less than twice the Debye radius, and the aperture of the meshes in the grid is 10-15 times of the diameter of the meshes of the grid.
2. The probe of claim 1 wherein insulating spacers are disposed between said baffle and adjacent said grids, between said collector and adjacent said grids, and between said floor and said collector.
3. The probe of claim 2 wherein said insulating spacer is an annular ring having an outer diameter equal to an inner diameter of said sleeve.
4. The probe of claim 3, wherein the upper surface of the ring is provided with a circular groove coaxial with the ring;
the baffle is arranged in a groove below the baffle and adjacent to the insulating gasket;
the grid mesh is arranged in a groove below the grid mesh and adjacent to the insulating gasket;
the collector is arranged in a groove below the collector and adjacent to the insulating gasket.
5. The probe of claim 2 wherein said dielectric spacer is a poly-tetrachloroethylene spacer.
6. The probe of claim 1 wherein said sleeve, said baffle, said floor, said collector, and said mesh have a permeability of no greater than 1.1.
7. The probe of claim 1, wherein the radius of the probe opening is not less than 1.06mm and not more than 10 mm.
8. The probe of claim 1, wherein the radius of the sleeve is not less than 34.2mm and not more than 100 mm.
9. The probe of claim 1 wherein said grid has an electrical conductivity of not less than 106S/m；
The hardness of the grid mesh is not less than 37 HRC;
the expansion coefficient of the grid is not more than 18.2m/m ℃ (at20-100 ℃);
the transmittance of the grid mesh is not less than 80%;
the meshes of the grid mesh are regular hexagonal through holes;
the distance between the adjacent grids is 4mm-7 mm.
10. A multi-grid ion energy analysis instrument, comprising: a probe according to any of claims 1 to 9.
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| CN201921125490.2U CN209896025U (en) | 2019-07-17 | 2019-07-17 | Multi-grid ion energy analysis instrument and probe thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113140441A (en) * | 2021-03-05 | 2021-07-20 | 中国科学院国家空间科学中心 | High-energy resolution particle detection device and detection method |
| CN113438786A (en) * | 2021-05-17 | 2021-09-24 | 中国科学院国家空间科学中心 | Device for collecting space thermal plasma |
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2019
- 2019-07-17 CN CN201921125490.2U patent/CN209896025U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113140441A (en) * | 2021-03-05 | 2021-07-20 | 中国科学院国家空间科学中心 | High-energy resolution particle detection device and detection method |
| CN113140441B (en) * | 2021-03-05 | 2021-11-09 | 中国科学院国家空间科学中心 | High-energy resolution particle detection device and detection method |
| CN113438786A (en) * | 2021-05-17 | 2021-09-24 | 中国科学院国家空间科学中心 | Device for collecting space thermal plasma |
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