CN111584337B - Expanding cup type diffusion and ion extraction system configuration of high-density plasma ion source - Google Patents
Expanding cup type diffusion and ion extraction system configuration of high-density plasma ion source Download PDFInfo
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Abstract
The invention discloses an expanding cup type diffusion and ion extraction system configuration of a high-density plasma ion source, which comprises the following components: a plasma generation area, an expansion cup and an ion flow leading-out and conveying system structure; the plasma generating region is connected with the plasma generating region, and the electrodes arranged on the wall surface of the expansion cup are used for applying a lateral voltage field, so that the plasma in the plasma generating region realizes the angular space separation of target ions and impurity ions in the process of spraying and diffusing the plasma to the expansion cup; and an extraction opening is arranged in the high-occupancy-ratio region of the target ions, and the ion flow extraction and transportation system structure is connected so as to extract high-purity target ions and then accelerate and transport the high-purity target ions to the target for beam-target interaction. Compared with the traditional ion axial extraction system without voltage application of the expansion cup, the ion axial extraction system can transport target ion beams to a target with higher ratio, greatly improves the extraction of target ions of the plasma source and the purity of the target, and effectively improves the application range and the use performance of the ion source.
Description
Technical Field
The present invention relates to the field of plasma technology, and more particularly, to an expanding cup diffusion and ion extraction system configuration for a high density plasma ion source.
Background
The ion source is widely applied to the fields of ion implantation, ion propulsion, accelerators, material modification and the like. The main body of the ion source system can be generally divided into two major parts, i.e., ion generation and ion extraction. For plasma ion sources, the plasma density is very high in the source region (e.g., n in a dual plasma source e ≈10 14 n/cm 3 Magnitude), an expansion cup type extraction system is generally adopted, so that the plasma is extracted from the extraction system after being reduced in density and homogenized in the expansion cup, and the plasma is accelerated to a target by adopting a high-voltage electrostatic accelerator to perform beam-target interaction. In the process of generating plasma in the plasma generating region, generally, physical and chemical reactions are complicated, the components of the generated plasma are complicated, and the generated plasma contains multiple components such as target ions and impurity ions in multiple valence states, electrons, neutral particles and the like. In the ion extraction system, in the working process of ion current extraction, target ions are extracted, and meanwhile impurity ions are also extracted. The extraction purity of the target ion current is an important index related to the quality of the ion source, and is also related to an important influence factor of the interaction efficiency of the beam target, because: (1) If the proportion of the impurity ions is high, the load effect of the extraction system is increased, and the volume, cost and performance indexes of the extraction configuration and an external source system are not favorable; (2) Extracting accelerated high-energy impurity ionsBombarding the target, which can cause the series effects of target damage, working instability, life reduction, etc.
Therefore, for the multi-component high-density plasma ion source, when the proportion of impurity ions is large in the process of extracting and accelerating transportation and targeting of target ion beams, the interaction of the beams on the target is not contributed, and the working performance of the multi-component high-density plasma ion source is greatly reduced. Therefore, it is important to improve the diffusion of the target ion flow and the ratio of the extracted ion flow to the target, in terms of the ion quality of the ion output from the ion source and its application.
Disclosure of Invention
The invention provides an expanding cup type diffusion and ion extraction system configuration of a high-density plasma ion source, which aims to solve the problems of improving the diffusion of target ion flow and the ratio of extraction and transportation to a target.
In order to solve the above problems, according to an aspect of the present invention, there is provided an expanding cup diffusion and ion extraction system configuration of a high density plasma ion source, comprising: a plasma generation area, an expansion cup and an ion flow leading-out and conveying system structure; the expansion cup is connected with the plasma generation area, and a lateral voltage field is applied by using electrodes distributed on the wall surface of the expansion cup, so that the plasma in the plasma generation area realizes the angular space separation of target ions and impurity ions in the process of spraying and diffusing to the expansion cup; and an extraction opening is arranged in the high-occupancy-ratio region of the target ions, and the ion flow extraction and transportation system structure is connected so as to extract high-purity target ions and then accelerate and transport the high-purity target ions to the target for beam-target interaction.
Preferably, wherein the expansion cup is of a hollow cylindrical configuration, the electrode arrangement and voltage application within the expansion cup comprises: the wall surface of the expansion cup adjacent to the plasma generation region adopts an insulating medium, the other wall surfaces of the expansion cup adopt metal electrode materials, and a voltage U is applied to the metal electrode 0 -U k (ii) a Or the wall surface of the expansion cup adjacent to the plasma generation region adopts an insulating medium, only the wall surface which is far away from the central axis in the lateral direction adopts a metal electrode material, the other wall surfaces adopt insulating media, and a voltage U is applied to the metal electrode 0 -U k (ii) a Wherein, U 0 Is the electrode potential of the plasma generation region adjacent to the expansion cup, U k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0。
Preferably, wherein under the action of the lateral voltage of the expansion cup, the angular spatial separation of the target ions and the impurity ions is realized according to the mass-to-charge ratio of the ions; wherein, for ions with small mass-to-charge ratio, the occupation ratio is larger along with the increase of the transverse distance; for ions with a large mass-to-charge ratio, the fraction is largest at the central axis and smaller as the lateral distance increases.
Preferably, 1 extraction opening is formed in the high-occupation area of the target ions from the wall surface of the expansion cup and used for extracting high-purity target ions, and the included angle between the beam extraction direction and the central axis is theta; if the mass-to-charge ratio of the target ions is smaller than that of the impurity ions, determining that the target ions are light ions, wherein theta is larger than 0 degree and smaller than 180 degrees; and if the mass-to-charge ratio of the target ions is larger than that of the impurity ions, determining that the target ions are heavy ions, and selecting theta =0 degrees.
Preferably, the outlet is made of porous structure, and the material and applied voltage of the outlet are the same as those of the wall surface of an adjacent expansion cup.
Preferably, the inclination of the ion current extraction transport system structure is consistent with a beam extraction direction angle theta; for target ions with the mass-to-charge ratio smaller than that of the impurity ions, the ion flow leading-out and conveying system adopts a ring-shaped leading-out opening, a ring-shaped accelerated conveying system and a ring-shaped target/leading-out electrode configuration; for target ions with mass-to-charge ratios larger than that of the impurity ions, the ion current leading-out and conveying system adopts an axial line type configuration; wherein the voltage of the target/extraction electrode is U 0 -U k -U b ，U b Is the voltage difference of the target/extractor electrode relative to the expander cup electrode, U b ＞0；U 0 Is the electrode potential, U, of the plasma generation region adjacent to the expansion cup k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0。
The invention provides an expansion cup type diffusion and ion extraction system configuration of a high-density plasma ion source, which has the beneficial effects that:
1. the system configuration realizes the application of a lateral electrostatic field by utilizing the arrangement of electrodes and media in an expansion cup area and the application of lateral voltage, so that target ions and impurity ions are separated in an angular space in the diffusion process, and the extraction angle of the high-purity target ions is selected according to the angular space, so that the configuration of an extraction port, an extraction system and a target is designed and determined.
2. According to the system configuration, space separation of target ions and other impurity ions in the diffusion homogenization process can be realized by applying a certain small-amplitude lateral extraction voltage on the electrode in the expansion cup area, and then the target ions are extracted and transported to the target in the high-proportion area to generate high-efficiency beam-target interaction.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
FIG. 1 is a schematic block diagram of an expanded cup diffusion and ion extraction system configuration 100 for a high density plasma ion source, in accordance with an embodiment of the present invention;
fig. 2 (a) and 2 (b) are schematic diagrams of the configuration of an expanded cup diffusion of light ions and a vertical type ion extraction system thereof, respectively, according to an embodiment of the present invention;
FIGS. 3 (a) and 3 (b) are schematic diagrams of an expanded cup diffusion of light ions and a sharp-angled ion extraction system configuration thereof, respectively, according to an embodiment of the present invention;
FIGS. 4 (a) and 4 (b) are schematic diagrams of an expanded cup diffusion of light ions and a blunt-type ion extraction system configuration thereof, respectively, according to an embodiment of the present invention;
FIGS. 5 (a) and 5 (b) are schematic diagrams of an expanded cup diffusion of heavy ions and an axial type ion extraction system configuration thereof, respectively, according to an embodiment of the present invention;
fig. 6 is a schematic view of an expanding cup diffusion and ion extraction system of a conventional high density plasma source.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same unit/element is denoted by the same reference numeral.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their context in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
The embodiment of the invention provides an expansion cup type diffusion and ion extraction system configuration of a high-density plasma ion source, which utilizes the expansion cup area electrode, medium arrangement and lateral voltage application to realize lateral electrostatic field application, so that target ions and impurity ions are separated in an angular space in the diffusion process, and the extraction angle of high-purity target ions is selected according to the lateral electrostatic field application, so that the configuration of an extraction port position, an extraction system and a target is designed and determined, the physical mechanism and the demand function which the whole system configuration wants to break through are clear, and the system configuration is simple in production, processing and assembly, easy to operate and strong in realizability; according to the system configuration, space separation of target ions and other impurity ions in the diffusion homogenization process can be realized by applying a certain small-amplitude lateral extraction voltage on the electrode in the expansion cup area, and then the target ions are extracted and transported to the target in the high-proportion area to generate high-efficiency beam-target interaction.
Fig. 1 is a schematic diagram of an expanded cup diffusion and ion extraction system configuration 100 for a high density plasma ion source, in accordance with an embodiment of the present invention. As shown in fig. 1, an embodiment of the present invention provides an expanded cup diffusion and ion extraction system configuration 100 for a high density plasma ion source, comprising: a plasma generation region 101, an expansion cup 102, and an ion stream extraction transport system structure 103.
Preferably, the expansion cup 102 is connected with the plasma generation region 101, and a lateral voltage field is applied by using electrodes arranged on the wall surface of the expansion cup, so that the plasma in the plasma generation region realizes the angular spatial separation of target ions and impurity ions in the process of spraying and diffusing to the expansion cup; and an extraction opening is arranged in the high-occupancy-ratio region of the target ions, and the ion flow extraction and transportation system structure 103 is connected to extract high-purity target ions and then accelerate and transport the target ions to the target for beam-target interaction.
Further, the expansion cup is in a hollow cylindrical configuration, and the electrode arrangement mode and the voltage application mode in the expansion cup comprise: the wall surface of the expansion cup adjacent to the plasma generation region adopts an insulating medium, the other wall surfaces of the expansion cup adopt metal electrode materials, and a voltage U is applied to the metal electrode 0 -U k (ii) a Or the wall surface of the expansion cup adjacent to the plasma generation region adopts an insulating medium, only the wall surface which is far away from the central axis in the lateral direction adopts a metal electrode material, the other wall surfaces adopt insulating media, and a voltage U is applied to the metal electrode 0 -U k (ii) a Wherein, U 0 Is the electrode potential, U, of the plasma generation region adjacent to the expansion cup k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0。
Furthermore, under the action of the lateral voltage of the expansion cup, the angular space separation of target ions and impurity ions is realized according to the mass-to-charge ratio of the ions; wherein, for ions with small mass-to-charge ratio, the proportion of the ions is larger along with the increase of the transverse distance; for ions with a large mass-to-charge ratio, the fraction is largest at the central axis and smaller as the lateral distance increases.
Furthermore, 1 extraction port is arranged in a high-occupation area of the target ions from the wall surface of the expansion cup and used for extracting high-purity target ions, and the included angle between the beam extraction direction and the central axis is theta; if the mass-to-charge ratio of the target ions is smaller than that of the impurity ions, determining that the target ions are light ions, wherein the value range of theta is more than 0 degree and less than 180 degrees; and if the mass-to-charge ratio of the target ions is larger than that of the impurity ions, determining that the target ions are heavy ions, and selecting theta =0 degrees.
Furthermore, the outlet is in a porous structure, and the material and the applied voltage of the outlet are the same as those of the wall surface of one adjacent expansion cup.
Further, the inclination of the ion current extraction and transportation system structure is consistent with a beam extraction direction angle theta; for target ions with the mass-to-charge ratio smaller than that of the impurity ions, the ion flow leading-out and conveying system adopts a ring-shaped leading-out opening, a ring-shaped accelerated conveying system and a ring-shaped target/leading-out electrode configuration; for target ions with mass-to-charge ratios larger than that of the impurity ions, the ion current leading-out and conveying system adopts an axial line type configuration; wherein the voltage of the target/extraction electrode is U 0 -U k -U b ，U b Is the voltage difference of the target/extractor electrode relative to the expander cup electrode, U b ＞0；U 0 Is the electrode potential of the plasma generation region adjacent to the expansion cup, U k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0。
For light ion extraction, the desirable range of theta is more than 0 degree and less than 180 degrees, and the system structure configurations under the condition that the beam extraction direction angle theta is a right angle, an acute angle and an obtuse angle are respectively given in fig. 2, fig. 3 and fig. 4; for heavy ion extraction, θ =0 °, as shown in fig. 5. Wherein (a) and (b) in each figure show the system configuration of the electrode arrangement and the voltage application mode of the expansion cup region in the two modesDetails are given. Wherein, the first mode is as follows: the wall surface (2) of the expansion cup adjacent to the plasma generation region adopts an insulating medium, the other wall surfaces (3 and 4) of the expansion cup adopt metal electrode materials, and a voltage U is applied to the metal electrode 0 -U k (ii) a The second way is: the wall of the expansion cup (2) adjacent to the plasma generating region is made of an insulating medium, only the wall (3) laterally far away from the central axis is made of a metal electrode material, and the other wall (4) is made of an insulating medium, and a voltage U is applied to the metal electrode 0 -U k ，U 0 Is the electrode potential of the plasma generation region adjacent to the expansion cup, U k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0，U k On the order of tens to hundreds of volts; the relative distance between the target and the expansion cup is d; electrode inner diameter of discharge region is r p The transverse radius of the interior of the expansion cup is R, and the axial height of the interior of the expansion cup is L.
Fig. 2 (a) and 2 (b) are schematic diagrams of the configuration of the expanded cup diffusion of light ions and the vertical type ion extraction system thereof, respectively, according to an embodiment of the present invention. As shown in fig. 2, which is a longitudinal sectional view of the physical structure, the system is divided into four areas: including a plasma generation region, an expansion cup region, an extraction acceleration region, and a target region, θ =90 °. The physical partition, each electrode/medium parameter and the voltage application mode are as follows: (1) is a plasma source region electrode with a voltage value of U 0 (ii) a (2) An expansion cup insulating medium; (3) for expanding the cup electrode, the voltage value is U 0 -U k (ii) a (4) In a first mode: for expanding the cup electrode, the voltage value is U 0 -U k (ii) a The second mode is as follows: no voltage is applied to expand the cup insulating medium; (5) is a target (or an extraction electrode) and has a voltage value of U 0 -U k -U b ，U b Is the voltage difference of the target/extractor electrode relative to the expander cup electrode, U b ＞0。
The physical functions and the working process of each area are as follows: (1) The plasma generation region is used for generating high-density plasma, and the components of the plasma generation region are complex and comprise target ions, impurity ions, electrons, neutral particles and the like. (2) The high-density plasma is sprayed into the expansion cup for diffusion homogenization. Wherein, the expanding cup electrodeThe arrangement and voltage application are divided into two types, and fig. 2 (a) is the first type: the wall surface (2) of the expansion cup adjacent to the plasma generation area is an insulating medium, the wall surfaces (3) and (4) of other expansion cups are metal electrodes, and the metal electrodes are applied with voltage U 0 -U k (ii) a FIG. 2 (b) shows a second embodiment: the wall surface (2) of the expansion cup adjacent to the plasma generation area is an insulating medium, the wall surface (3) far away from the central axis is a metal electrode, and a voltage U is applied to the metal electrode 0 -U k And the wall surface (4) is made of a medium material. The outlet may be porous and the material and applied voltage are selected to be the same as the wall of one adjacent expansion cup. Under the action of the external lateral electrostatic field, ions with different mass-to-charge ratios are subjected to angular space separation. When the target ions are light ions with small mass-to-charge ratio, the distribution density of the target ions in the lateral edge area is higher, so that the extraction purity of the light ions is higher due to the extraction opening formed at the lateral edge area. (3) The leading-out port adopts an annular structure, an annular accelerated conveying system and an annular target structure are adopted, and a voltage difference U is applied between the expansion cup electrode and the target b The electrostatic field causes ions to be extracted and accelerated to the target for beam-target interaction.
For example, the light ion beam flow extraction transport direction angle θ =90 °, the plasma generation region generates high-density plasma, and the plasma density at the inlet of the expansion cup is 3.2 × 10 16 n/m 3 Left and right, the structural parameter r p 1mm, R =4.5mm, L =4.5mm, and d is about 40 mm. Selecting voltage parameters in the model: u shape 0 ＝100V,U k ＝100V,U b =10kV. The electrode arrangement and the potential application mode of the expansion cup adopt two modes: 1) The wall surface of the expansion cup adjacent to the plasma generation region is an insulating medium, the wall surfaces of other expansion cups are metal electrodes, and a voltage U is applied 0 -U k =0V; 2) The wall surface of the expansion cup adjacent to the plasma generation area is an insulating medium, and the cylindrical wall surface of the side surface of the expansion cup far away from the central axis adopts a metal electrode and is applied with a voltage U 0 -U k And =0V, and the other wall surfaces are made of dielectric materials.
FIGS. 3 (a) and 3 (b) are an expanded cup diffusion of light ions and acute angle type ions thereof, respectively, according to an embodiment of the present inventionLeading to a schematic diagram of the system configuration. As shown in FIG. 3, 0 ° < θ < 90 °, the physical partitioning, electrode/dielectric parameters, and voltage application are the same as in the embodiment of FIG. 2. The physical functions and work flows of the zones are substantially the same as those of the figure 2, and the difference from the figure 2 is that: in fig. 3, the beam extraction direction angle θ is an acute angle, and the overall configuration gradient of the beam extraction transport system is consistent with the beam extraction direction. The position of the outlet on the wall surface of the expansion cup is shown in figure 3. The arrangement of the electrodes of the expansion cup and the voltage application are divided into two types, and fig. 3 (a) is the first type: the wall surface (2) of the expansion cup adjacent to the plasma generation area is an insulating medium, the wall surfaces (3) and (4) of other expansion cups are metal electrodes, and the metal electrodes are applied with voltage U 0 -U k (ii) a FIG. 3 (b) shows a second embodiment: the wall surface (2) of the expansion cup adjacent to the plasma generation area is an insulating medium, the wall surface (3) far away from the central axis is a metal electrode, and a voltage U is applied to the metal electrode 0 -U k And the wall surface (4) is made of a medium material. The outlet may be porous and the material and applied voltage are selected to be the same as the wall of one adjacent expansion cup.
For example, the beam extraction transport direction angle θ =45 °, the plasma generation region generates high-density plasma, and the plasma density at the inlet of the expansion cup is 1 × 10 17 n/m 3 ，r p 1mm, R =4.5mm, L =4.5mm, and d is about 40 mm. Voltage value U 0 ＝50V,U k ＝50V,U b =10kV. Expanding cup electrode arrangement and potential application mode: the wall surface of the expansion cup connected with the discharge area electrode is an insulating medium, the wall surfaces of other expansion cups are all metal electrodes, and a voltage U is applied 0 -U k ＝0V。
Fig. 4 (a) and 4 (b) are schematic diagrams of the configuration of the diverging cup diffusion of light ions and the obtuse-angle type ion extraction system thereof, respectively, according to an embodiment of the present invention. As shown in FIG. 4, 90 < θ < 180, the physical partitioning, electrode/media parameters, and voltage application are the same as in the embodiment of FIG. 2. The physical functions and work flows of the zones are substantially the same as those of the figure 2, and the difference from the figure 2 is that: in fig. 4, the beam extraction direction angle θ is an acute angle, and the overall configuration gradient of the beam extraction transport system is consistent with the beam extraction direction. Expansion cupThe position of the wall surface with the outlet is shown in figure 4. The arrangement of the electrodes of the expansion cup and the voltage application are divided into two types, and fig. 4 (a) is the first type: the wall surface (2) of the expansion cup adjacent to the plasma generation region is an insulating medium, the wall surfaces (3) and (4) of other expansion cups are metal electrodes, and the metal electrodes are applied with a voltage U 0 -U k (ii) a Fig. 4 (b) shows a second type: the wall surface (2) of the expansion cup adjacent to the plasma generation region is an insulating medium, the wall surface (3) far away from the central axis is a metal electrode, and a voltage U is applied to the metal electrode 0 -U k And the wall surface (4) is made of a medium material. The outlet may be porous and the material and applied voltage are selected to be the same as the wall of one adjacent expansion cup.
Fig. 5 (a) and 5 (b) are schematic diagrams of the configuration of the expanded cup diffusion of heavy ions and the axial type ion extraction system thereof, respectively, according to an embodiment of the present invention. As shown in fig. 5, θ =0 °, the physical division, the electrode/medium parameters, and the voltage application method are the same as those in the embodiment of fig. 2. Lateral voltage is applied through the expansion cup electrode to enable ions with different mass-to-charge ratios to realize angular space separation to a certain degree, wherein the density of heavy ions near the central axis is higher, so that an extraction port is formed on the axis, and an axial extraction acceleration system is adopted to extract and transport the heavy ions. The electrode arrangement and the potential application mode of the expansion cup area are respectively two: fig. 5 (a) shows a first: the wall surface (2) of the expansion cup adjacent to the plasma generation region is an insulating medium, the wall surfaces (3) and (4) of other expansion cups are metal electrodes, and the metal electrodes are applied with a voltage U 0 -U k (ii) a FIG. 5 (b) shows a second embodiment: the wall surface (2) of the expansion cup adjacent to the plasma generation region is an insulating medium, the wall surface (3) far away from the central axis is a metal electrode, and a voltage U is applied to the metal electrode 0 -U k And the wall surface (4) is made of a medium material. The outlet can adopt a porous structure, and the material and the applied voltage of the outlet are the same as the wall surface of the adjacent expansion cup.
Fig. 6 is a schematic view of an expanding cup diffusion and ion extraction system of a conventional high density plasma source. As shown in FIG. 6, in the physical model of the conventional diffusion and extraction system with expanded cup, the physical partition, the parameters of each electrode/medium, and the voltage application methodComprises the following steps: (1) is a plasma source region electrode with a voltage value of U 0 (ii) a (2) And (3) an expanded cup wall surface electrode with the same voltage as that of the plasma source region electrode and U 0 (ii) a (4) Is a target (or an extraction electrode) and has a voltage value of U 0 -U b . In the traditional structure, all wall electrodes of the expansion cup are the same as the electrode voltage of the plasma source region, and the plasma performs diffusion movement without external field effect in the expansion cup.
In an embodiment of the present invention, as shown in table 1, the ion transport ratio results of the vertical type light ion extraction system under the first expanded cup electrode arrangement and voltage embodiment shown in fig. 2 (a) are shown. The model parameters are: the plasma generating region generates plasma with a plasma density of 3.2 × 10 at the inlet of the expansion cup 16 n/m 3 On the left and right, the initial hydrogen and titanium ion loading rates were 1:1, the target ion is a hydrogen ion having a small mass-to-charge ratio. The structural parameter r p 1mm, R =4.5mm, L =4.5mm, and d is about 40 mm. Voltage parameter selection: u shape 0 ＝100V,U k ＝100V,U b =10kV. A first expanded cup electrode arrangement and voltage implementation was used. The simulation results in table 1 show that, in this example, the ratio of hydrogen ions to titanium ions extracted from the extraction port and transported to the target is 4.52, 1, which is higher than the purity of hydrogen ions that can be transported by the conventional homogeneous type (the extraction transport ratio of hydrogen ions to titanium ions is 1 under the same operating conditions).
In an embodiment of the present invention, as shown in table 2, the ion transport ratio results of the vertical light ion extraction system under the second expanded cup electrode arrangement and voltage embodiment shown in fig. 2 (b) are shown. The model parameters are: the plasma generating region generates plasma with a plasma density of 3.2 × 10 at the inlet of the expansion cup 16 n/m 3 On the left and right, the initial hydrogen and titanium ion loading rates were 1:1, the target ion is a hydrogen ion having a small mass-to-charge ratio. The structural parameter r p θ =1mm, r θ =4.5mm, l θ =4.5mm, and d may be about 40 mm. Voltage parameter selection: u shape 0 θ＝100V,U k ＝100V,U b =10kV. A second expansion cup electrode arrangement and voltage implementation was used. Watch (A)1, the ratio of hydrogen ions to titanium ions extracted from the extraction port and transported to the target in this example is 3.21, which is higher than the purity of hydrogen ions that can be transported by a conventional homogeneous type (the output ratio of hydrogen ions to titanium ions is 1 under the same operating conditions).
In an embodiment of the present invention, as shown in table 3, the ion transport ratio results of the acute-angle type light ion extraction system in the first extended cup electrode arrangement and voltage embodiment shown in fig. 3 (a) are shown. Wherein the model parameters are: theta =45 DEG, the plasma generating region generates plasma, and the plasma density at the inlet of the expansion cup is set to 1 × 10 17 n/m 3 About, the initial hydrogen and titanium ion loading rates were 1:1, the target ion is a hydrogen ion having a small mass-to-charge ratio. The structural parameter is r p θ =1mm, r =4.5mm, l =4.5mm, d is 20mm. The voltage parameters are selected as follows: u shape 0 ＝50V,U k ＝50V,U b =10kV. A first expanded cup electrode arrangement and voltage implementation was used. The simulation results in table 3 show that, in this example, the ratio of hydrogen ions to titanium ions extracted from the extraction port and transported to the target is 1.6, which is higher than the purity of hydrogen ions that can be transported by the conventional homogeneous type (the ratio of hydrogen ions to titanium ions output is 1 under the same operating conditions).
Table 1 ion transport ratio results for vertical light ion extraction system under first extended cup electrode arrangement and voltage implementation
Table 2 ion transport ratio results for vertical light ion extraction system under second expanded cup electrode arrangement and voltage implementation
Table 3 ion transport ratio results for acute angle type light ion extraction system under the first extended cup electrode arrangement and voltage implementation
From the results in tables 1 and 2, it can be seen that the two expansion cup electrode arrangements and voltage embodiments both enable the expansion cup to have an ion separation effect therein, and the purity of the light ions extracted by the extraction system is greatly improved. As can also be seen from the results in the table, the heavy ions collected on the wall surface at the right end of the expansion cup (i.e., the wall surface (4) in fig. 2) have a larger proportion than the light ions, which indirectly verifies that: when the target ions are heavy ions, the extraction and transport purity of the heavy ions can be effectively improved in the direction of theta =0 degrees by adopting the arrangement of the expanding cup electrodes and the voltage implementation mode. As can be seen from a comparison of the results of tables 1, 2 and 3, the greater the light ion beam current extraction angle θ, the higher the purity of the light ion stream extracted from the annular extraction port and transported to the target.
The results of table 1, table 2 and table 3 verify: by adopting the system configuration corresponding to the two expansion cup electrode arrangements and the voltage implementation modes provided by the embodiment of the invention, the feasibility of extracting and transporting the target purity of target ions can be effectively improved, the ratio of target ion beam current transported to the target is higher, the extraction and target purity of the target ions in the plasma source are greatly improved, and the application range and the use performance of the ion source are effectively improved.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ means, component, etc ]" are to be interpreted openly as referring to at least one instance of said means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (5)
1. An expanded cup diffusion and ion extraction system configuration for a high density plasma ion source, comprising: a plasma generation area, an expansion cup and an ion flow leading-out and conveying system structure; the expansion cup is connected with the plasma generation area, and a lateral voltage field is applied by using electrodes distributed on the wall surface of the expansion cup, so that the plasma in the plasma generation area realizes the angular space separation of target ions and impurity ions in the process of spraying and diffusing to the expansion cup; an extraction port is formed in a high-occupancy-ratio region of the target ions and connected with the ion flow extraction and transportation system structure so as to extract high-purity target ions and then accelerate and transport the high-purity target ions to a target for beam-target interaction;
wherein, the expansion cup is in a hollow column shape, and the electrode arrangement mode and the voltage application mode in the expansion cup comprise: the wall surface of the expansion cup adjacent to the plasma generation region adopts an insulating medium, the other wall surfaces of the expansion cup adopt metal electrode materials, and a voltage U is applied to the metal electrode 0 -U k (ii) a Or the wall surface of the expansion cup adjacent to the plasma generation area adopts an insulating medium, only the wall surface which is laterally far away from the central axis adopts a metal electrode material, the other wall surfaces adopt insulating media, and a voltage U is applied to the metal electrode 0 -U k (ii) a Wherein, U 0 Is the electrode potential of the plasma generation region adjacent to the expansion cup, U k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0。
2. The system configuration according to claim 1, characterized in that under the action of the lateral voltage of the expansion cup, an angular spatial separation of target ions and impurity ions is achieved according to the mass-to-charge ratio of the ions; wherein, for ions with small mass-to-charge ratio, the occupation ratio is larger along with the increase of the transverse distance; for ions with a large mass-to-charge ratio, the fraction is largest at the central axis and smaller as the lateral distance increases.
3. The system configuration of claim 1, wherein 1 extraction port is arranged in the high-occupancy region of the target ions from the wall surface of the expansion cup for extracting high-purity target ions, and the angle between the beam extraction direction and the central axis is theta; if the mass-to-charge ratio of the target ions is smaller than that of the impurity ions, determining that the target ions are light ions, wherein the value range of theta is more than 0 degree and less than 180 degrees; and if the mass-to-charge ratio of the target ions is larger than that of the impurity ions, determining that the target ions are heavy ions, and selecting theta =0 degrees.
4. The system configuration of claim 1, wherein the exit port is porous and is made of the same material and applied with the same voltage as the wall of an adjacent expansion cup.
5. The system configuration of claim 1, wherein the ion stream extraction transport system structure has a tilt corresponding to a beam extraction direction angle θ; for target ions with mass-to-charge ratios smaller than the mass-to-charge ratio of the impurity ions, the ion flow leading-out and conveying system adopts a configuration of an annular leading-out opening, an annular accelerated conveying system and an annular target/leading-out electrode; for target ions with mass-to-charge ratios larger than the mass-to-charge ratio of the impurity ions, the ion current leading-out and conveying system adopts an axial line type structure; wherein the voltage of the target/extraction electrode is U 0 -U k -U b ，U b Is the voltage difference of the target/extractor electrode relative to the expander cup electrode, U b ＞0，U 0 Is the electrode potential of the plasma generation region adjacent to the expansion cup, U k To expand the voltage difference of the cup electrode relative to the plasma source region electrode, U k ＞0。
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| CN102711355B (en) * | 2012-06-14 | 2014-12-03 | 东北师范大学 | Penning anion source ceramic neutron tube |
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