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 inductively coupled plasma mass spectrometers (ICP-MS) can include a high-temperature plasma stream that evaporates and ionizes a sample, and as a result, 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 skimmer are typically grounded. However, a spectroscopic measurement device can also be operated such that one or both of the sampler and skimmer are not grounded. Further, a spectrometer device typically requires a vacuum to operate, and the plasma stream must be maintained at a very high temperature up to 10,000 K. Thus, the components within a 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 a spectroscopic measurement device, which can lead to conflicting design requirements.

Summary of the Invention

[0005] The inventor has recognized that the above-mentioned conflicting design requirements can be addressed by providing a spacer element within the interface assembly to electrically insulate the orifice element from the remainder of the interface assembly while also making an electrical connection to the orifice element. This is achieved by providing a spacer element between the orifice element and a cooling element (such as a cooling plate) of the interface assembly, as detailed below, to facilitate an insulated electrical connection to the orifice element while maintaining sufficient heat transfer from the orifice element to the cooling element.

[0006] In a first implementation form, a spacer element is provided for a plasma interface assembly in a spectroscopic measurement device. The plasma interface comprises an orifice element defining an orifice for passing plasma (or charged ions in the plasma) from a plasma source, and a cooling element for cooling the orifice element. In 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 spectrometry device or an optical spectrometry device.

[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 and prevents unwanted movement of charge across components within the device that could lead to changes in the electric field or interference, calibration or measurement interference, component damage, or safety risks with charged ions within the interface. The electrical insulator is provided with an opening that facilitates positioning the electrical insulator between and around the orifice element and the cooling element. The electrical insulator may be flat within reasonable manufacturing tolerances to conform to the orifice element and / or the cooling element. Advantageously, this allows for a secure fit between the components of the interface assembly and minimizes the spacing between the components of the interface assembly. The opening in the electrical insulator may be any space or gap within the electrical insulator through which ions generated by 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 enables 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, so as to be in electrical communication with the orifice element. In this way, a voltage can be applied to the orifice element to generate an electric field having a selected bias voltage as part of the interface assembly. For example, the intensity of the ion flow from the plasma source can be increased by passing the ions through an electric field biased in a desired direction.

[0009] The spacer element may comprise a contact tab extending from the conductive layer and configured to function as an electrical contact for facilitating electrical connection with the conductive layer. The contact tab may be provided on a corresponding extending portion of the electrical insulator. In some examples, the contact tab may extend substantially radially outward from the conductive layer at an angle substantially perpendicular within the plane of the spacer element, such as at approximately a right angle, or at any angle away from the conductive layer within the plane, such as in a direction away from the electrical insulator or through the electrical insulator.

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

[0011] The electrical insulator may have a thickness of 90 to 110 μm, or be thicker than 110 μm, for example 150 μm, or be 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 achieved for the desired thermal regulation. For example, the electrical insulator can have a thinner thickness in an implementation using a material with a limited intrinsic thermal conductivity, or a thicker thickness in an implementation using a material with a higher thermal conductivity. An example of an electrical insulator with sufficient heat transfer characteristics is a polyimide layer or plate, such as Kapton®.

[0012] The conductive layer can include any conductive material known in the art, such as copper. For example, the layer may include a copper foil and / or copper tracks disposed on the surface of the electrical insulation 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 disposed on the conductive layer. Advantageously, by providing a gold layer on the conductive layer, for example on a copper track, the conductive layer becomes inert and it becomes possible to use the spacer in the immediate vicinity of the plasma in a vacuum. In some examples, the gold layer has a thickness of 2 μm to 5 μm. Nevertheless, it will be understood that gold layers thicker than 5 μm can also be used. The gold layer is conductive and thus electrical conduction between the conductive layer and the orifice element is maintained.

[0014] As described herein, the spacer element functions to electrically insulate the orifice element from other components of the interface assembly while allowing for electrical connection to the orifice element. Additionally, the material geometry of the spacer ring can promote heat conduction and enable sufficient cooling of the orifice element by the cooling element. In this way, the spacer ring advantageously combines the opposing properties of electrical insulation and thermal conductivity. For example, the spacer ring may have a total thickness of 135 μm ± 15 μm. In other examples, the spacer element can have a thickness greater than 135 μm (e.g., a thickness of 1 mm demonstrated by a greater thickness of conductive copper and / or a greater thickness of an electrical insulator) while still maintaining sufficient thermal conductivity. Importantly, the material and respective geometry of the spacer element are provided to maintain the operating temperature of the orifice element and surrounding components by cooling the components through the cooling element. For example, the spacer element can have a thermal conductivity of 0.1 to 0.5 watts per (meter kelvin). It will be understood that higher or lower thermal conductivities are 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 a through-hole for accommodating a fixture within the interface assembly. The through-hole may be disposed around the spacer element. The fixture can include any suitable fixture known in the art, such as bolts, screws, or rivets, for fixing the orifice element to the cooling element and fixing the spacer element therebetween.

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

[0017] In some examples, the orifice element may comprise one or a combination of a skimmer and a sampler. The skimmer and sampler may each be a skimmer cone and a 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 a plurality of 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, the spacer element is disposed at a position between the orifice element and the cooling element to electrically insulate the orifice element while enabling an electrical connection to the orifice element.

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

Figure 2

Figure 3

Figure 4

Figure 5a

Figure 5b

Figure 6

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 constraints, and thermal / electrical conduction criteria. The spacer element 200 combines these requirements with various technical characteristics such as functionality in proximity 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, etc.

[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 the sampler cone 104 have operating temperatures of several hundred degrees Celsius, and thus the components are adjusted during the operation of the mass spectrometer to prevent damage from the high-temperature plasma, which can be up to 10,000 °C, and to reduce interference with the sample (e.g., 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 the sampler cone 104 are in thermal communication with the cooling plate 108. In particular, as best shown in FIG. 4, the skimmer cone 104 is held at a predetermined position on the mass spectrometer side of the cooling plate 108 using a fixture 110. The sampler cone 102 is spaced from the skimmer cone 104 and is disposed on the opposite side of the cooling plate 108 (the side facing the plasma source). The interface region 103 between the two cones within the interface assembly is maintained at a low pressure, e.g., 100 - 300 Pa. As best shown in FIG. 1, the interface assembly 100 is held at a predetermined position within the spectroscopic measurement device using fixtures on the cooling plate 108.

[0027] The spacer element 200 is disposed 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 (FIG. 5a) of the spacer element 200. As will be described in more detail below with reference to FIG. 5, the spacer element 200 is provided such that the electrical insulator 202 contacts the cooling plate 108 and the conductive layer 204 contacts the skimmer cone holder 106. The spacer element 200 further comprises an electrical contact tab 206 configured to enable 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 insulated from the cooling plate 108 and the sampler cone 102, thus enabling voltage to be provided to the skimmer cone 104 without interfering with the other components of the interface assembly 100.

[0028] The skimmer cone 104 is adjusted to a temperature that is not too high as to damage the components and not too low as to interfere with the sample. This can be adjusted with a (liquid or gas) coolant passing through the coolant channel 109, and is achieved by providing a cooling plate 108 that functions as a heat sink for the skimmer cone 104. The spacer element 200 that separates 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. For example, other cooling configurations without coolant channels that provide cooling fins on the cooling plate 108 or an externally applied coolant flow are equally possible.

[0029] The interface assembly 100 may also include an O-ring (not shown) disposed between the skimmer 104 and the skimmer holder 106 within the O-ring groove 107, which seals the skimmer 104 for vacuum separation between the plasma source and the mass spectrometer. The O-ring also has to be adjusted 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 the sampler cone 102 across the interface assembly 100. In this way, the skimmer cone 104 and the skimmer cone holder 106 are electrically insulated. Nevertheless, it will be appreciated that the spacer element 200 or a second spacer element (not shown) can be disposed between the sampler cone 102 and the cooling plate 108 to electrically insulate the sampler cone 102 from the cooling plate 108 and the skimmer cone 104.

[0031] Figures 5a, 5b, and 6 show various views of the spacer element 200. In particular, Figure 5a shows the face of the spacer element 200 configured to contact the skimmer cone assembly, and Figure 5b shows the opposite face 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 enable electrical communication with the skimmer cone 104 and / or the skimmer cone holder 106 (however, it will be understood that an alternative option, namely, contact with and separation from the sampler cone 102, is possible). The spacer element comprises a conductive layer 204 on an electrical insulator 202. The contact tab 206 extends from the conductive layer 204 and functions as an electrical contact to facilitate the supply of voltage to the conductive layer 204. In some implementations, the contact tab is 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 an adjacent interface component (e.g., the skimmer cone holder 106), and a circumferential gap is provided adjacent to the contact tab 206 to prevent the circle from forming a closed electrical loop.

[0033] The compact form of the spacer element 200 can minimize the impact on the spacing between the skimmer cone 102 and the sampler cone 104. In particular, the spacer element 200 is substantially flat to conform to the components of the interface assembly 100 and provide a secure fit. For example, the spacer element 200 has a through-hole 114 around it configured to accommodate a fixture 110 that attaches 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 device and allow for a minimum temperature deviation on the skimmer holder 106 and the skimmer cone 104.

[0034] The form and function of the spacer element 200 advantageously balance electrical insulation properties and heat conduction properties. For example, as best shown in FIG. 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 insulation properties and functions as a base for the spacer element 200, enabling the spacer element 200 to electrically insulate the cooling plate 108 and the 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 that 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. Thus, as best shown in FIG. 6, a gold layer 302 can be provided on the copper layer 304. Advantageously, the gold layer renders the spacer element 200 sufficiently inert so as not to interfere with the sample analysis within the mass spectrometer and is conductive to maintain electrical communication with the copper layer 304.

[0038] Advantageously, the manufacture of the layered circuit board can be easily reproduced without specialized tools or methods. Thus, the spacer element 200 can be manufactured economically and in sufficient quantities.

[0039] The overall thickness of the spacer element 200 of FIG. 6 is 138 μm, which achieves but does not exceed the heat transfer rate required by the skimmer cone 104. The thickness of the selected material as shown in FIG. 6 is selected according to the surrounding components, that is, to meet the specific thermal conductivity of the surrounding components of the interface assembly 100, and provides a spacer 200 having a thermal conductivity suitable for the device as described above. Other practical materials and thicknesses other than the specific examples shown may be implemented with the spacer elements disclosed herein as needed to meet the specific requirements of different spectroscopic measurement devices, as can be readily recognized or tested without undue experimentation.

[0040] In particular, it should be understood that the above description is illustrative and not limiting. Many other implementations will be apparent to those skilled in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to specific exemplary implementations, it is recognized that the present disclosure is not limited to the described implementations and can be practiced using modifications and variations within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be construed in an illustrative rather than a limiting sense. Therefore, the scope of the present invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A spacer element for a plasma interface assembly in a spectroscopic measurement device, wherein the interface assembly comprises an orifice element defining an orifice for passing plasma from a plasma source, 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, the electrical insulator having an opening therein, and 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, the contact tab being 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 any one of claims 1 to 3, wherein the electrical insulator is substantially ring-shaped so as to enable ions to pass through the orifice when the spacer element is disposed 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, preferably 90 μm to 110 μm.

6. The spacer element according to any one of claims 1 to 5, wherein the electrical insulator includes a polyimide layer.

7. The spacer element according to any one of claims 1 to 6, wherein the conductive layer includes a copper foil.

8. The spacer element according to any one of claims 1 to 7, wherein the conductive layer includes a copper track disposed on the surface of the electrical insulator.

9. The spacer element according to any one of claims 1 to 8, wherein the conductive layer has a thickness of 30 μm to 40 μm.

10. The spacer element according to any one of claims 1 to 9, further comprising a gold layer disposed on the conductive layer.

11. The spacer element according to claim 10, wherein the gold layer has a thickness of 2 μm to 5 μm.

12. The spacer element according to any one of claims 1 to 11, wherein the spacer element has a thermal conductivity of 0.1 to 0.5 watt / (meter·kelvin).

13. The spacer element according to any one of claims 1 to 12, further comprising a through hole for accommodating a fixture for fixing the orifice element to the cooling element.

14. An interface assembly for a spectrometer comprising an orifice element disposed on a cooling element, the interface assembly comprising the spacer element according to any one of claims 1 to 13 provided between the orifice element and the cooling element; and an electrical lead for supplying a voltage to the orifice element, the electrical lead being connected to the spacer element.

15. The interface assembly according to claim 14, wherein the orifice element comprises a skimmer.

16. The interface assembly according to claim 14 or 15, wherein the orifice element comprises a sampler.

17. The interface assembly according to any one of claims 14 to 16, wherein the orifice element comprises a plurality of components such as an orifice cone and an orifice cone holder.

18. A spectroscopic measuring device comprising the interface assembly according to any one of claims 14 to 17, wherein the spectroscopic measuring device is a mass spectrometer or an optical spectrometer.

19. The spacer element according to any one of claims 1 to 13, the interface assembly according to any one of claims 14 to 17, or the spectroscopic measuring device according to claim 18, wherein the cooling element comprises a cooling plate.

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