Spacer for orifice element

Abstract

To provide a spacer element for a plasma interface assembly in a spectrometry measurement apparatus, for example in a mass spectrometry measurement apparatus.SOLUTION: A spacer element for a plasma interface assembly in a spectrometry measurement apparatus, for example in a mass spectrometry measurement apparatus, is disclosed. In particular, the spacer element is for an interface assembly comprising an orifice element defining an orifice for passing plasma from a plasma source, and a cooling element for cooling the orifice element. The spacer element comprises an electrically isolating body configured to be inserted between the orifice element and the cooling element. The electrically isolating body is provided with an opening. An electrically conductive layer is provided on the electrically isolating body to face the orifice element.SELECTED DRAWING: Figure 5a

Description

Technical Field

[0001] The present disclosure relates to a spacer for an orifice element of a spectroscopic measurement device.

Background Art

[0002] Spectroscopic measurement devices, such as mass spectrometers (ICP-MS) using inductively coupled plasma, can include a high-temperature plasma stream that evaporates and ionizes a sample, such that ions from the sample can be processed or introduced into a spectrometer for measurement or analysis. The extraction and transfer of ions from the plasma involves guiding a portion of the ions formed by the plasma through an interface assembly that facilitates bridging the pressure difference between the plasma source and the spectrometer. The interface assembly can include a first orifice provided in a sampler and a second, often narrower, orifice (commonly referred to as a sampler cone and a skimmer cone, respectively) provided in a skimmer.

[0003] In conventional spectroscopic measurement devices, the sampler and the skimmer are typically grounded. However, the spectroscopic measurement device can also be operated such that one or both of the sampler and the skimmer are not grounded. Further, the spectrometer device typically requires a vacuum to operate, and the plasma stream must be maintained at a very high temperature up to 10,000K. Thus, the components within the spectroscopic measurement device, particularly those within the interface assembly, must be adjusted without interfering with the transfer of ions or adversely affecting the measurement and analysis, and must withstand the harsh conditions imposed by the high-temperature plasma.

[0004] Thus, there are a number of different technical (e.g., electrical, thermal, and material) requirements that must be met within the spectroscopic measurement device, which can lead to conflicting design requirements.

Summary of the Invention

[0005] The inventors recognized that the conflicting design requirements described above could be addressed by providing a spacer element within the interface assembly to electrically isolate the orifice element from the rest of the interface assembly, while also providing an electrical connection to the orifice element. This is achieved by providing a spacer element between the orifice element and the cooling element (such as a cooling plate) of the interface assembly, as detailed below, to facilitate an isolated electrical connection to the orifice element while maintaining sufficient heat transfer from the orifice element to the cooling element.

[0006] In the first implementation, a spacer element is provided for a plasma interface assembly in a spectroscopic measuring device. The plasma interface comprises an orifice element defining an orifice for allowing plasma (or charged ions in the plasma) from a plasma source to pass through, and a cooling element for cooling the orifice element. During use, the plasma flows through the plasma interface into a spectrometer, such as a mass spectrometer. In particular, the device may be, for example, a mass spectrometer or an optical spectrometer.

[0007] The spacer element comprises an electrical insulator configured to be inserted between the orifice element and the cooling element. In this way, the spacer element electrically insulates the orifice element to prevent undesirable movement of charge across components in the apparatus, which could lead to changes in the electric field or interference with charged ions in the interface, calibration or measurement interference, component damage, or safety risks. The electrical insulator is provided with openings, which facilitate the placement of the electrical insulator between and around the orifice element and the cooling element. The electrical insulator may be flat within reasonable manufacturing tolerances to fit the orifice element and / or the cooling element. Advantageously, this allows for secure mating between components of the interface assembly and minimizes the spacing between components of the interface assembly. The openings in the electrical insulator may be any space or gap within the electrical insulator through which ions generated in the plasma source can flow.

[0008] The spacer element also comprises a conductive layer provided on an electrical insulator so as to face the orifice element. In this way, when the electrical insulator is inserted between the orifice element and the cooling element, the conductive layer can be electrically coupled to the orifice element. The layered configuration of the spacer element allows for electrical conduction with the orifice element without any electrical contact with the cooling element, while preventing electrical interference with other components of the spectroscopic measurement assembly. In this way, a voltage can be applied to the orifice element to generate an electric field with a selected bias voltage to a part of the interface assembly. For example, the intensity of an ion flow from a plasma source can be increased by passing ions through an electric field biased in a desired direction.

[0009] The spacer element may include contact tabs that extend from the conductive layer and are configured to function as electrical contacts to facilitate electrical connection with the conductive layer. The contact tabs may be provided on the corresponding extended portion of the electrical insulator. In some examples, the contact tabs may extend substantially radially outward from the conductive layer, such as at approximately a right angle in the plane of the spacer element, or at any angle away from the conductive layer in the plane, such as away from or through the electrical insulator.

[0010] The electrical insulator may be substantially annular or ring-shaped to accommodate the common form factor of the orifice elements and to allow plasma and / or ions to pass through the opening when spacer elements are positioned between and around the orifice elements and the cooling elements. For example, the electrical insulator may be a closed ring shape, C-shape, ellipse, or square. In some examples, the shape of the electrical insulator conforms to the shape of the cooling elements, orifice elements, or other components of the interface assembly.

[0011] The electrical insulator may be 90-110 μm thick, or thicker than 110 μm, for example 150 μm, or thinner than 90 μm, for example 50 μm. It will be understood that minimizing the thickness of the electrical insulator provides higher thermal conductivity and maximizes the cooling of the orifice element by the cooling element. A balance can be struck for the desired thermal control. For example, the electrical insulator may have a thinner thickness in mounting configurations using materials with limited intrinsic thermal conductivity, or a thicker thickness in mounting configurations using materials with higher thermal conductivity. An example of an electrical insulator with sufficient heat transfer properties is a polyimide layer or plate, e.g., Kapton®.

[0012] The conductive layer may include any conductive material known in the art, such as copper. For example, the layer may include copper foil and / or copper tracks placed on the surface of the electrical insulating layer. The total thickness of the spacer may be less than 1 mm. The thickness of the conductive layer may be, for example, 30 μm to 40 μm.

[0013] In some examples, the spacer element further comprises a gold layer placed on top of the conductive layer. Advantageously, by providing the gold layer on top of the conductive layer, for example, on a copper track, the conductive layer becomes inert, allowing the spacer to be used in a vacuum very close to the plasma. In some examples, the gold layer is 2 μm to 5 μm thick. Nevertheless, it will be understood that gold layers thicker than 5 μm may also be used. The gold layer is conductive, and therefore electrical conduction between the conductive layer and the orifice element is maintained.

[0014] Spacer elements, as described herein, function to electrically isolate the orifice element from other components of the interface assembly while allowing electrical connection to the orifice element. In addition, the material geometry of the spacer ring can facilitate thermal conduction, allowing for sufficient cooling of the orifice element by a cooling element. Thus, the spacer ring advantageously combines the conflicting properties of electrical insulation and thermal conductivity. For example, a spacer ring may have a total thickness of 135 μm ± 15 μm. In other examples, spacer elements can have thicknesses greater than 135 μm (e.g., 1 mm thickness, demonstrated by greater thicknesses of conductive copper and / or electrical insulators) while still maintaining sufficient thermal conductivity. Importantly, the material and respective geometry of the spacer elements are provided to maintain the operating temperature of the orifice element and surrounding components by cooling them through a cooling element. For example, a spacer element can have a thermal conductivity of 0.1 to 0.5 watts / (meter-kelvin). It will be understood that higher or lower thermal conductivity is also possible depending on the use of specific materials or the design of the interface assembly.

[0015] In some examples, the spacer element further comprises through-holes for accommodating fasteners within the interface assembly. The through-holes may be positioned around the spacer element. The fasteners may secure the orifice element to the cooling element and the spacer element between them, and may include any suitable fasteners known in the art, such as bolts, screws, or rivets.

[0016] In another implementation, the interface assembly for the spectrometer comprises an orifice element positioned on a cooling element (such as a cooling plate). The cooling element may be a gas or liquid cooled through a coolant channel in the cooling plate, for example, with water at a temperature of 15°C to 25°C. A spacer element is positioned between the orifice element and the cooling element, as described above. In addition, the interface assembly comprises electrical leads for supplying voltage to the orifice element, and these electrical leads are connected to the spacer element. The spacer element may be detachably fixed between the orifice element and the cooling element, which is advantageous as it facilitates the replacement of the spacer element.

[0017] In some examples, the orifice element may comprise one or a combination of a skimmer and / or a sampler. The skimmer and / or sampler may be a skimmer cone and / or sampler cone, respectively, or may be formed in other suitable shapes known to those skilled in the art.

[0018] In some examples, the orifice element may comprise multiple components, such as a skimmer and a skimmer holder. Alternatively, the orifice element may be a single workpiece, and / or the orifice element holder may be part of another structure of the spectroscopic measuring device. In both such examples, a spacer element is positioned between the orifice element and the cooling element to electrically insulate the orifice element while allowing electrical connection to the orifice element.

[0019] In another implementation, the spectroscopic measuring device comprises the interface assembly and spacer elements described above. The spectroscopic measuring device may be a mass spectrometer or an optical spectrometer. For example, the device may be an inductively coupled plasma mass spectrometer (ICP-MS), or the device may be an inductively coupled plasma optical spectroscopic measuring system for, for example, inductively coupled plasma emission spectroscopy (ICP-OES).

[0020] Here, the disclosed implementations are described with reference to the accompanying drawings as examples for illustrating aspects of the present disclosure.

Brief Description of the Drawings

[0021] [Figure 1] The top view of an interface assembly for a spectroscopic measurement device is shown. [Figure 2] The cross-sectional view of the interface assembly of FIG. 1 along the cutting line shown in FIG. 1 is shown. [Figure 3] The side view of the interface assembly of FIG. 1 is shown. [Figure 4] The exploded view of the interface assembly of FIG. 1 is shown. [Figure 5a] FIGS. 5a and 5b show the top view and the bottom view of a spacer element for a plasma interface assembly, respectively. [Figure 5b] FIGS. 5a and 5b show the top view and the bottom view of a spacer element for a plasma interface assembly, respectively. [Figure 6] The cross-sectional view of the spacer element of FIG. 5a is shown.

Modes for Carrying Out the Invention

[0022] For the sake of brevity, the following specific description is described with reference to an inductively coupled plasma mass spectrometry (ICP-MS) device. However, it will be understood that the present disclosure can be readily applied to any known spectroscopic measurement device, for example, a plasma interface assembly for emission spectroscopy or mass spectrometry.

[0023] The environment in the interface within an ICP-MS device can be particularly harsh, involving high temperatures, substantial pressure differences, charged plasma flows, geometric restrictions, and thermal / electrical conductivity criteria. The spacer element 200 combines these requirements with various technical characteristics of a component, such as functionality close to the charged plasma, functionality at high temperatures, functionality in a vacuum, being inert or non-reactive so as not to affect the sample, electrical insulation, thermal conductivity, a constant and minimum spacing between components of the interface assembly, ease of replacement, and economic manufacturability.

[0024] Figures 1 - 4 show various views of an interface assembly 100 for guiding ions from a plasma source to a spectrometer. In particular, Figure 2 shows a cross-section as shown in Figure 1, Figure 3 shows a side view, and Figure 4 shows an exploded view for showing various components of the interface assembly.

[0025] The interface assembly 100 includes a sampler cone 102, a skimmer cone 104, a skimmer cone holder 106, a spacer element 200, and a cooling plate 108. Although a specific description refers to the cooling plate 108, it will be understood that this is an example of a more general cooling element. Both the skimmer cone 102 and the sampler cone 104 facilitate the transfer of ions from a plasma source, typically at atmospheric pressure, to the analysis region of a mass spectrometer, which is at a vacuum or very low pressure. During operation, hot ions move through the orifice 112a of the sampler cone 102, generating an ion beam that passes through the smaller orifice 112b of the skimmer cone 104, and the ion beam enters the vacuum within the mass spectrometer. For example, the orifice 112b may be 0.5 mm and the orifice 112a may be 1 mm. Methods of operating a general interface assembly for an ICP-MS device are known in the art and are not the focus of the present disclosure, which relates to providing a spacer element between at least one of the orifice elements and the cooling plate 108.

[0026] The skimmer cone 102 and sampler cone 104 have operating temperatures of several hundred degrees Celsius, and therefore, the components are adjusted during the operation of the mass spectrometer to prevent damage from high-temperature plasma, which can be up to 10,000°C, and to reduce interference with the sample (e.g., to reduce sample deposition). For example, the temperature at the tip of the skimmer cone 102 can be about 600°C with a plasma power of 1600 W. For this purpose, the skimmer cone 102 and sampler cone 104 are in thermal communication with the cooling plate 108. In particular, as best shown in Figure 4, the skimmer cone 104 is held in place on the mass spectrometer side of the cooling plate 108 using a fixture 110. The sampler cone 102 is spaced apart from the skimmer cone 104 and positioned on the opposite side of the cooling plate 108 (the side facing the plasma source). The interface region 103 between the two cones in the interface assembly is maintained at a low pressure, e.g., 100-300 Pa. As best shown in Figure 1, the interface assembly 100 is held in place within the spectroscopic measuring device using fasteners on the cooling plate 108.

[0027] The spacer element 200 is positioned between the skimmer cone holder 106 and the cooling plate 108, and these are held together by a fixture 110. The skimmer cone 104 is positioned on the skimmer cone holder 106 within the opening 208 (Figure 5a) of the spacer element 200. As will be described in more detail below with reference to Figure 5, the spacer element 200 is provided such that an electrical insulator 202 is in contact with the cooling plate 108 and a conductive layer 204 is in contact with the skimmer cone holder 106. The spacer element 200 further comprises an electrical contact tab 206 configured to allow the supply of voltage to the skimmer cone 102 via the conductive layer 204 of the spacer element 200. In this way, the skimmer cone 104 is electrically isolated from the cooling plate 108 and the sampler cone 102, and thus allows voltage to be supplied to the skimmer cone 104 without interfering with other components of the interface assembly 100.

[0028] The skimmer cone 104 is regulated to a temperature that is not too high to damage its components and not too low to interfere with the sample. This can be regulated by a coolant (liquid or gaseous) passing through a coolant channel 109 and is achieved by providing a cooling plate 108 that acts as a heat sink for the skimmer cone 104. A spacer element 200 separating the skimmer cone 104 from the cooling plate 108 is thin enough and / or thermally conductive to allow heat transfer from the skimmer cone 104 to the cooling plate 108. Other cooling configurations without coolant channels are also possible, for example, providing the cooling plate 108 with cooling fins or a coolant flow applied from the outside.

[0029] The interface assembly 100 may also include an O-ring (not shown) positioned between the skimmer 104 and the skimmer holder 106 in an O-ring groove 107, which seals the skimmer 104 for vacuum separation between the plasma source and the mass spectrometer. The O-ring must also be conditioned within the operating temperature, which can be facilitated by the thermal properties of the spacer element 200.

[0030] As described above, the spacer element 200 prevents electrical conduction from the skimmer cone holder 106 to the cooling plate 108 and sampler cone 102 across the interface assembly 100. In this way, the skimmer cone 104 and the skimmer cone holder 106 are electrically isolated. Nevertheless, it will be understood that the sampler cone 102 can be electrically isolated from the cooling plate 108 and the skimmer cone 104 by placing the spacer element 200 or a second spacer element (not shown) between the sampler cone 102 and the cooling plate 108.

[0031] Figures 5a, 5b, and 6 show various views of the spacer element 200. In particular, Figure 5a shows a side of the spacer element 200 configured to contact the skimmer cone assembly, and Figure 5b shows the opposite side of the spacer element 200 configured to abut the cooling plate 108. Figure 6 shows a cross-sectional view of one possible configuration of the spacer element 200.

[0032] The conductive layer of the spacer element 200 is configured to allow electrical communication with the skimmer cone 104 and / or the skimmer cone holder 106 (although it will be understood that alternative options, namely contact and separation with the sampler cone 102, are also possible). The spacer element comprises a conductive layer 204 on top of an electrical insulator 202. Contact tabs 206 extend from the conductive layer 204 and function as electrical contacts to facilitate the supply of voltage to the conductive layer 204. In some implementations, the contact tabs are omitted and electrical contact can be made directly on the conductive layer 204. In either case, spring contacts can be used to connect to the conductive layer 206. The conductive layer 204 is circular to optimize electrical contact with adjacent interface components (e.g., the skimmer cone holder 106), and a circumferential gap is provided adjacent to the contact tabs 206 to prevent the circular shape from forming a closed electrical loop.

[0033] The compact form of the spacer element 200 minimizes its impact on the spacing between the skimmer cone 102 and the sampler cone 104. In particular, the spacer element 200 is substantially flat to fit into the components of the interface assembly 100 and provide a secure fit. For example, the spacer element 200 has through holes 114 around it configured to accommodate fasteners 110 for attaching the skimmer 104 and the skimmer cone holder 106 to the cooling plate 108. The material properties of the spacer element 200 allow for a constant spacing of the skimmer 104 relative to the cooling plate 108 during operation of the ICP-MS apparatus, and enable minimal temperature deviation on the skimmer holder 106 and the skimmer cone 104.

[0034] The form and function of the spacer element 200 are advantageous in that they balance electrical insulation properties and thermal conductivity properties. For example, as best shown in Figure 6, the spacer element 200 comprises a gold layer 302 having a thickness of 3 μm, a copper foil layer 304 having a thickness of 35 μm, and a substrate layer 306 having a thickness of 100 μm.

[0035] The substrate layer 306 has electrical insulating properties and functions as the base for the spacer element 200, allowing the spacer element 200 to electrically insulate the cooling plate 108 and sampler cone 102 from the skimmer cone 104.

[0036] The copper foil layer 304 is applied to one side of the polyimide substrate and has a suitable geometric shape to enable electrical contact with the skimmer holder 106 and / or the skimmer cone 104. For example, the copper foil layer 304 may be in electrical contact with the skimmer holder 106 which is in electrical communication with the skimmer cone 104, or the copper foil layer 304 of the spacer element 200 may be in direct contact with the skimmer cone 104.

[0037] If the components of the interface assembly 100 are not inert, the reaction may affect the sample measurement, potentially interfering with the discrete m / z values ​​or contributing as continuous background noise. Copper is reactive and typically oxidizes if left uncoated. Therefore, a gold layer 302 can be provided on the copper layer 304, as best shown in Figure 6. Advantageously, the gold layer is conductive, ensuring that the spacer element 200 is sufficiently inert to avoid interfering with the sample analysis in the mass spectrometer while maintaining electrical communication with the copper layer 304.

[0038] Advantageously, the manufacturing of layered circuit boards can be easily replicated without specialized tools or methods. Therefore, the spacer elements 200 can be manufactured economically and in sufficient quantities.

[0039] The overall thickness of the spacer element 200 in Figure 6 is 138 μm, which achieves, but does not exceed, the heat transfer coefficient required by the skimmer cone 104. The thickness of the selected material, as shown in Figure 6, is selected depending on the surrounding components, i.e., to satisfy the specific thermal conductivity of the surrounding components of the interface assembly 100, and provides a spacer 200 with thermal conductivity suitable for the apparatus described above, for example. Other practical materials and thicknesses other than the specific examples shown may be implemented with the spacer elements disclosed herein, as necessary to satisfy the specific requirements of different spectroscopic measuring instruments, so that they can be easily recognized or tested without performing excessive experiments.

[0040] In particular, please understand that the above description is illustrative and not restrictive. Many other implementations will become apparent to those skilled in the art upon reading and understanding the above description. While this disclosure has been described with reference to specific exemplary implementations, it will be recognized that this disclosure is not limited to the described implementations and can be implemented using modifications and changes within the spirit and scope of the appended claims. Therefore, this specification and drawings should be understood as illustrative, not restrictive. Accordingly, the scope of the invention should be determined with reference to the appended claims, along with the entire scope of equivalents to which such claims are granted.

Claims

1. A spacer element for a plasma interface assembly in a spectroscopic measuring device, wherein the interface assembly comprises an orifice element defining an orifice for allowing plasma from a plasma source to pass through, and a cooling element for cooling the orifice element, and the spacer element is An electrical insulator configured to be inserted between the orifice element and the cooling element, wherein the electrical insulator has an opening, A spacer element comprising: a conductive layer provided on the electrical insulator so as to face the orifice element.

2. The spacer element according to claim 1, further comprising a contact tab extending from the conductive layer, wherein the contact tab is configured to enable electrical connection with the conductive layer.

3. The spacer element according to claim 2, wherein the contact tab extends substantially radially outward from the conductive layer.

4. The spacer element according to claim 1, wherein the electrical insulator is substantially ring-shaped so as to allow ions to pass through the orifice when the spacer element is positioned between the orifice element and the cooling element.

5. The spacer element according to any one of claims 1 to 4, wherein the electrical insulator has a thickness of 50 μm to 150 μm.

6. The spacer element according to any one of claims 1 to 4, wherein the electrical insulator has a thickness of 90 μm to 110 μm.

7. The spacer element according to any one of claims 1 to 4, wherein the electrical insulator includes a polyimide layer.

8. The spacer element according to claim 7, wherein the conductive layer includes copper foil.

9. The spacer element according to any one of claims 1 to 4, wherein the conductive layer includes a copper track disposed on the surface of the electrical insulator.

10. The spacer element according to claim 5, wherein the conductive layer has a thickness of 30 μm to 40 μm.

11. The spacer element according to any one of claims 1 to 4, further comprising a gold layer disposed on the conductive layer.

12. The spacer element according to claim 11, wherein the gold layer has a thickness of 2 μm to 5 μm.

13. The spacer element according to any one of claims 1 to 4, wherein the spacer element has a thermal conductivity of 0.1 to 0.5 watts / (meter-kelvin).

14. The spacer element according to any one of claims 1 to 4, further comprising a through hole for accommodating a fastener for fixing the orifice element to the cooling element.

15. An interface assembly for a spectrometer comprising an orifice element positioned on a cooling element, wherein the interface assembly is A spacer element according to any one of claims 1 to 4 is provided between the orifice element and the cooling element, An interface assembly comprising an electrical lead wire for supplying voltage to the orifice element, wherein the electrical lead wire is connected to the spacer element.

16. The interface assembly according to claim 15, wherein the orifice element comprises a skimmer.

17. The interface assembly according to claim 16, wherein the orifice element comprises a sampler.

18. The interface assembly according to claim 15, wherein the orifice element comprises a plurality of components such as an orifice cone and an orifice cone holder.

19. A spectroscopic measuring device comprising the interface assembly described in claim 15, wherein the spectroscopic measuring device is a mass spectrometer or an optical spectrometer.

20. The interface assembly according to claim 15, wherein the cooling element comprises a cooling plate.

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