Gas capture element

Abstract

A gas capture element 10 for capturing gas within a non-evaporable getter (NEG) pump comprises a surface structure comprising a plurality of structure elements generated by additive manufacturing. The

Description

The present invention relates to a gas capture element for capturing gas within a non-evaporable getter (NEG) pump. Further the present invention relates to a method for manufacturing such a gas capture element. NEG pumps are commonly used as ultra-high vacuum (UHV) pumps in which layers of sintered disks of NEG material are heated and activated inside of the device. NEG coated hardware is also used in some UHV applications both to reduce the effect of surface outgassing in pipework but also to act as an additional pumping mechanism. It is known that the pumping speed of a NEG is directly proportional to its active surface area. Most current sintered disks have deliberately high porosity to achieve this. However, hardware such us pipes or other vacuum components are coated with an NEG material usually by sputtering which provides a smooth and compact surface. Thus, the active surface of the NEG coated hardware is determined by the surface area of the component itself which tends to have insufficient pump activity. It is an object of the present invention to provide a gas capture element with enhanced pump activity. The problem is solved by a gas capture element according to claim 1 and a method according to claim 11. A gas capture element according to the present invention for capturing gas with-ing a non-evaporable getter pump comprises a surface structure. The surface structure comprises a plurality of structure elements generated by additive manufacturing. Additive manufacturing is a well-known technique to manufacture small but precise structures even from metals by adding material in a determined way at predefined positions to create those structure elements. Additive manufacturing has developed in the past and thus also very small structures down to a microscale are feasible with this technique. Also, different kinds of metals can be used for additive manufacturing that can provide a pumping effect as NEG material when activated. Thus, additive manufacturing provides a versatile and reliable technique in order to create the surface structure of the gas capture element. Hence by the additive manufacturing structure elements are added to the surface thereby increasing the active surface which leads to an improved pump performance, i. e. pumping speed, of the gas capture element. Preferably, the structure elements are built as pillars or microvilli. By these structures the surface can be increased. In particular pillars or microvilli are suitable in order to increase the surface-to-area ratio. This ratio determines the active surface of the gas capture element over a specific area. In the prior art the surface-to-area ratio is equal to 1 when spattering is used to coat hardware. When is above 1, it is indicating that the active surface is increased for the same area. Alternatively, the increase of the active surface by the present invention can be also quantified by a surface-to-volume ratio, wherein the surface is the active surface providing a pumping effect and the volume is the volume of the getter material. Increasing the surface-to-volume ration results in an increased active surface for a constant amount of getter material. Thus, the surface-to-area ration and the surface-to-volume ration can be both used to determine the increased active surface provided by the present invention. Preferably, the surface-to-area ratio is larger than 10 and preferably larger than 100 and most preferably larger than 1000. Thus, by the present invention sufficient increase of pumping speed by the increased surface of the NEG material is achieved. Preferably, the structure elements have a ratio of height to width above 10, preferably above 20. Thus, by small and high structure elements sufficient increase of surface of the NEG material is achieved. Preferably, the structure elements have a height of between 5pm and 1000pm, preferably between 50pm and 500pm. Thus, depending on the abilities of the additive manufacturing technique sufficient high structure elements can be provided on the surface structure of the gas capture element in order to increase the active surface of the gas capture element. Preferably, the structure elements have a width of between 1pm and 100pm, preferably between 10pm and 100pm. Thus, the structure elements can be made sufficiently small in order to be placed close together such that a large number of structure elements can be placed within an area to increase the active surface of the gas capture element. Preferably, the distance between two adjacent structure elements is smaller than 50pm, preferably smaller than 20pm and most preferably smaller than 10pm. Thus, adjacent structure elements can be placed in close proximity to each other. Thereby the number of structure elements per area can be increased, increasing the active surface of the gas capture element. Preferably, the periodicity of the structure elements, denoting a distance from a center point of one structure element to the center point of neighboring structure element is smaller than 100pm, preferably smaller than 50pm and most preferably smaller than 20pm. Thus, by a small periodicity of the structure elements, a high density of structure elements within an area can be achieved increasing the active surface of the gas capture element. Preferably, the surface structure is regularly patterned. Since additive manufacturing gives a choice about where to place the structure elements, a regularly patterned surface structure can be achieved. Preferably, the surface structure has a structure element density of more than 10 / cm2, more preferably more than 100 / cm2 and most preferably more than 1000 / cm2. Thus, a sufficient large number of structure elements can be placed within one area in order to increase the active surface of the gas capture element. Preferably, the structure elements are substantially identical or different. Therein substantial in these terms means identical within the accuracy of the additive manufacturing process. Preferably, the structure elements are made from an NEG material such as Zirconium (Zr), Vanadium (Va), Titanium (Ti), Tantalum (Ta), Hafnium (Hf), Iron (Fe), Aluminum (Al) or an alloy of one or more of these elements. In another aspect of the present invention a method for generating a gas capture element for capturing gas within a non-evaporable getter pump is provided including the steps of depositing an NEG material by additive manufacturing onto a surface to create a surface structure. Preferably, the method is built along the features of the gas capture element described before. In the following the present invention is described in more detail with reference to the accompanying figures. The figures show: Figure 1 a schematic representation of a gas capture element in a sectional view and Figure 2 a schematic representation of the gas capture element of figure 1 in a top view. A gas capture element 10 comprises a surface 14. The surface 14 may be the surface of a vacuum hardware such as pipes or other types of vacuum components. Onto surface 14 the structure elements 12 are generated by additive manufacturing. The structure elements 12 are built from any NEG material such as Zr, Ti, Ta or an alloy of one or more of these elements. In the example of the figures, the structure elements are built as pillars or microvilli. However, the present invention is not limited to this specific form of the structure elements. The structure elements 12 may have different shapes. In addition the present invention is also not limited to the specific number of structure elements shown in the figures and usually the gas capture element 10 of the present invention comprises a large number of structure elements generated onto the surface 14 by additive manufacturing. Further, in the example of the figures all structure elements are indicated to be similar or even identical. However, the present invention is not limited to this configuration and different structure elements may have different shapes or dimension all employed in one gas capture element. Further, in the example of the figures it is show that the structure elements are regularly patterned over the surface area of the hardware. This is in particular feasible due to using additive manufacturing as technique for creating the structure elements and differs to random processes such as sputtering, growths or any other conventional deposition method. The structure elements 12 may have a height H, a width W, a distance between adjacent structure elements D and a periodicity of A. The height H of the structure elements may be between 5pm and 1000pm, preferably between 50pm and 500|jm. The width W of the structure elements 12 may be between 1pm and 100pm, preferably between 10pm and 100pm. The distance D between to adjacent structure elements 12 may be smaller than 50pm, more preferably smaller than 20pm and most preferably smaller than 10pm. The periodicity △ may be smaller than 100pm, preferably smaller than 50pm and most preferably smaller than 20pm. In particular the ratio H / W of height H to width W of the structure elements is preferably above 10 and more preferably above 20. Thus, by the configuration of the structure elements and their dimensions, a high density of structure elements can be achieved. In particular the structure element density may be more than 10 / cm2, preferably more than 100 / cm2 and more preferably more than 1000 / cm2. Thus, a high number of structure elements 12 can be placed within an area in order to increase a surface-to-area ratio. The surface-to-area ratio determines the active surface provided by the structure elements divided by the area of the surface 14 in which the structure elements 12 are arranged. Preferably, the surface-to-area ratio is larger than 10, preferably larger than 100 and more preferably larger than 1000. Thus, a substantial increase of the active surface can be achieved by using additive manufacturing technique when creating structure elements to increase the active NEG coated surface. Thereby pump performance and in particular pumping speed of the NEG material can be increased. Reference list: Gas capture element 10 Structure element 12 Surface 14 CLAIMS

Claims

1, A gas capture element for capturing gas within a non-evaporable getter pump, said gas capture element comprising a surface structure comprising a plurality of structure elements generated by additive manufacturing, wherein the structure elements are made from a NEG material and built as pillars or microvilli.

2. The gas capture element according to claim 1, wherein a surface-to-area ratio is larger than 10, preferably larger than 100 and more preferably larger than 1000.

3. The gas capture element according to claim 1 or 2, wherein the structure elements have a ratio of height to width above 10, preferably above 20.

4. The gas capture element according to any of claims 1 to 3, wherein structure elements have a height of between 5pm and 1000pm, preferably between 50pm and 500pm.5, The gas capture element according to any of claims 1 to 4, wherein the structure elements have a width of between 1pm and 100pm, preferably between 10pm and 100pm.6, The gas capture element according to any of claims 1 to 5, wherein the distance between two adjacent structure elements is smaller than 50pm, preferably smaller than 20pm and most preferably smaller than 10pm.

7. The gas capture element according to any of claims 1 to 6, wherein the surface structure is regularly patterned.8, The gas capture element according to any of claims 1 to 7, wherein the surface structure has a structure element density of more than 10 / cm2, preferably more than 100 / cm2 and most preferably more than 1000 / cm2.

9. The gas capture element according to any of claims 1 to 8, wherein the structure elements are substantial identical or different.

10. The gas capture element according to any of claims 1 to 9, wherein the structure elements are made from Zr, Ti, Ta, Hf, Fe, V, Al or an alloy of one or more of these elements.

11. Method for generating a gas capture element for capturing gas within a non-evaporable getter pump, including depositing an NEG material by additive manufacturing onto a surface to create a surface structure comprising a plurality of structure elements, wherein the structure elements are built as pillars or microvilli.

12. Method according to claim 11, wherein the surface structure is built according to the gas capture element of any of claims 1 to 10.

13. NEG pump comprising at least one gas capture element according to any of claims 1 to 10 or manufactured by claim 11 or 12.

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