NEG element

Abstract

NEG element and NEG cartridge, in particular for an NEG pump, comprising a lattice structure, wherein the lattice structure is made from an NEG material.

Description

[0001] NEG ELEMENT

[0002] The present invention relates to a non-evaporable getter (NEG) element and an NEG cartridge comprising such an NEG element. Further, the present invention relates to an NEG vacuum pump with such an NEG element.

[0003] Common NEG pumps comprise NEG elements made from an NEG material, wherein by the NEG material gas molecules and particles from a vessel are captured by physical sorption at the surface of the NEG elements thereby creating a vacuum in the vessel. If the complete surface of the NEG elements is occupied, reactivation of the NEG elements becomes necessary by heating of the NEG elements above a certain reactivation temperature. Hence, the NEG elements on the one hand need a large surface to increase the pump performance and on the other hand need to be arranged in contact with or close proximity to a heater in order to be able to reactivate the NEG material.

[0004] Common NEG elements are shaped as disks, which are stacked along a cylindrical ceramic resistive heater. By each disk an additional surface is provided increasing the pump performance of the NEG pump. Therein, the NEG disks are fabricated in the prior art by sintering or pressing the NEG material. Hence, the possible shapes of the NEG elements are very limited and so are the possibilities to increase their surface.

[0005] It is an object of the present invention to provide an NEG element with an increased pump performance.

[0006] The problem is solved by a non-evaporable getter (NEG) element according to claim 1 , an NEG cartridge according to claim 16 and a vacuum pump according to claim 20.

[0007] The NEG element, in particular for an NEG pump, according to the present invention comprises a, the opening extends through the whole base element or at least partially into the base element along the axial direction of the base element. Further, a lattice structure at least partially, and preferably fully, surrounds the base element. Preferably, the base element is in the center of the lattice structure. In particular, the lattice structure surrounds the lateral surface of the preferably cylindrical base element and may in some embodiments extend at least at one end beyond the axial end of the cylindrical base element. In particular, if the opening of the base element is built as blind hole, the lattice structure may extend beyond the axial end of the base element of a side, which does not contain the opening of the blind hole. Hence, the heater can be inserted into the base element from the other side, lattice structure that made from an NEG material. The lattice structure is considered an arrangement of lattice elements in a regular, repeating geometric pattern extending two or three dimensions, which defines the spatial organization of the NEG material. Due to the lattice structure the surface of the NEG material is increased thereby increasing the pump performance, i.e. pumping speed and capacity of the NEG element. Therein, an NEG material is any material which acts as getter material by physisorption of gas particles and molecules (in particular after activation) to the surface of the NEG element.

[0008] Preferably, the vacuum structure may be any component of a vacuum apparatus such as a chamber wall, a vacuum pipe, a deflector plate, a pipe connection, a part of a flange, a base element of an NEG cartridge or the like.

[0009] Preferably the vacuum structure provides a flat surface, a bended surface, a rounded surface or an arbitrarily shaped surface to which the lattice structure is connected. In particular, the lattice structure is manufactured to adapt to the shape of the surface of the vacuum structure.

[0010] Preferably, the lattice structure is built or made by additive manufacturing such as direct metal laser sintering (DMLS) or the like.

[0011] Preferably, the lattice structure is built directly onto the vacuum structure, in particular by additive manufacturing. Thus, the vacuum structure may serve as substrate for the additive manufacturing process. Hence, the lattice structure can be easily adapted to the shape of the vacuum structure and a stable and robust connection between the vacuum structure and the lattice structure is ensured. Alternatively, the lattice structure can be manufactured separate from and distant of the vacuum structure and subsequently attached to the vacuum structure by fixing means, soldering, brazing, welding, clamping or the like. The lattice structure may also be inserted in a respective recess or volume provided by the vacuum structure without additional fixing means. For example, the vacuum structure may be a vacuum pipe surrounded by an external pipe to reduce leakage, then the lattice structure may be inserted in the space between the vacuum pipe and the external pipe or the like.

[0012] Preferably, the lattice structure and the vacuum structure are fabricated in the same fabrication step, i.e. by a layer-by-layer fabrication according to the additive manufacturing.

[0013] Preferably, the vacuum structure is made of stainless steel, aluminum, titanium, copper or any alloy thereof. In particular, the vacuum structure is made of the same material as the lattice structure, in particular if the vacuum structure and the lattice structure are made together by additive manufacturing.

[0014] Preferably, the lattice structure is optically blind, in particular in a radial direction or in a tangential direction. Herein, optical blindness refers to the property of the lattice structure that no straight line can be drawn from the lateral surface of the base element to the radial outer surface of the lattice structure or across the lattice structure in a tangential direction. Thus, gas particles entering the lattice structure are trapped within the lattice structure, thereby increasing the likelihood that the gas particles collide with a surface of the lattice structure to be absorbed by the surface of the NEG material formed by the lattice structure. In other words, when seen from the side, it is not possible to optically look through the lattice structure and the lattice structure is completely obstructing any direct and straight path through the NEG cartridge in a radial or tangential direction. At the same time, heat radiation from a heating element to activate or reactive the NEG element is efficiently captured by the lattice structure and efficient activation is enabled.

[0015] Preferably, the lattice structure has a volume filling factor of less than 25% and preferably less than 15%. Therein, the volume filling factor defines the portion of the total or bulk volume VT occupied by the structural elements of the lattice structure. In other words, the volume filling factor is the ratio of VS / VT with Vs the volume of the structural elements of the lattice structure. A theoretical volume filling factor of 0% would mean the absence of any lattice structure and a volume filling factor 100% would mean a bulk element of the NEG material. According to the present invention the volume filling factor is preferably between 5% and 25% and more preferably between 5% and 15%. Hence, likelihood of gas particles entering the volume of the lattice structure is increased due to the low filling factor of the lattice structure, while at the same time the surface is increased by the lattice structure such that even for such low volume filling factors a sufficient large surface of the NEG material is provided by the lattice structure.

[0016] Preferably, the lattice structure is made from titanium (Ti), Ti64 or another Ti alloy. Therein, it has been shown that Ti, Ti64 or another Ti alloy act as a getter material and can be used as NEG material after activation. At the same time, it has been shown that Ti, Ti64 or another Ti alloy can be used in additive manufacturing and in particular in DMLS.

[0017] Preferably, the lattice structure is made from zirconium (Zr), Hafnium (Hf), Tantal (Ta), Vanadium (V) or alloys thereof in particular in combination with iron (Fe) and / or aluminum (Al).

[0018] Preferably, the lattice structure has a homogeneous porosity and in particular the porosity is constant over substantially the entire lattice structure. Alternatively, the lattice structure has an inhomogeneous porosity and in particular the porosity changes in the radial direction of the lattice structure. Therein, the porosity is defined as the ratio of the volume Vv of the voids to the overall or bulk volume VT. Therein Vv=1-Vs as defined with regard to the volume filling factor. In particular, the porosity is described by the ratio Vv / VT. Due to use of additive manufacturing, the porosity can be tailored to the specific application and needs. In particular, the porosity may decrease in the radial direction from the center to the outer side of the lattice structure. Hence, gas particles are efficiently trapped within the volume of the lattice structure and likelihood of a collision of the gas particles with structural elements of the lattice structure is enhanced. Due to the decreased porosity in the radial direction, it is unlikely for gas particles which have entered the volume of the lattice structure to leave the lattice structure again. Hence, pump performance is increased due to an increase of the likelihood of the gas particles being adsorbed by the lattice structure.

[0019] Preferably, the lattice structure comprises a plurality of layers. In each layer substantially identical lattice elements are used to create the lattice structure. In particular, the lattice elements in a single layer are regularly and evenly arranged or distributed. Hence, the individual layers comprise a specific number of lattice elements to form the respective layer, wherein the lattice structure is built by the consecutive arrangement of layers in a radial direction. Therein, by each layer a cylindrical shell is formed providing part of the volume of the lattice structure, wherein in the cylindrical shell the respective lattice elements of the layer are arranged. Alternatively, the layers are arranged along a direction perpendicular to a surface of the vacuum structure. Thus, the layers are stacked onto each other and from the lattice structure.

[0020] Preferably, adjacent layers overlap by more than 2%, preferably by more than 5% and more preferably by more than 10% to create structural and thermal connection between the lattice elements of the adjacent layers. Consequently, a certain layer of the lattice structure extends into the adjacent layer such that a volume overlap of 2% or more, preferably, 5% or more and more preferably 10% or more is established. By this overlap, the lattice elements of one layer are merged with lattice element of the adjacent layer. Thereby, structural stability of the lattice structure is provided. At the same time, areas of overlap provide the contact surfaces necessary for heat conduction across the lattice in order to heat up the lattice structure for activation or reactivation.

[0021] Preferably, the lattice structure is created by a regularly repeated arrangement of a lattice element. In particular the lattice element is provided by a wire which may be regularly shaped, for example as helix, circle, straight, round wavy or any other shape that is used to form a regular pattern.

[0022] Preferably, one or more layers comprise a lattice element formed as a clockwise or counterclockwise helically shaped wire. Therein, the direction “clockwise” and / or “counter-clockwise” are defined when looked at the NEG element from above, i.e. from the end of an NEG cartridge formed by the NEG element opposite to the base plate or in a direction perpendicular or substantially perpendicular to the surface of the vacuum structure. Hence, one layer may comprise a clockwise helically shaped wire, wherein a directly adjacent layer may comprise a counter-clockwise helically shaped wire. In particular, also the combination of clockwise and counterclockwise helically shaped wires in a single layer is possible in order to create a meshed structure in that single layer.

[0023] Preferably, the wire is round, i.e. comprises a circular cross-section. Alternatively, the wire is elliptical ly shaped, i.e. has an elliptical cross-section. Therein, preferably the long axis of the ellipse extends tangentially to the lattice structure and the short axis extends radially. Hence, by the elliptical shape of the wire the surface of the lattice structure is increased without substantially influencing the filling factor of the lattice structure. Of course, round and elliptical wires can be mixed in a single lattice structure such that for example the wires of one layer are formed round, wherein the wires of another layer can be formed el liptically . Thereby, the porosity can be tailored according to the specific need and in accordance with the trade-off of maximizing the parameters of surface of the lattice structure, trapping ability for gas particles, which already have entered the lattice structure, and the ability of gas particles entering the lattice structure. In particular, the wire has a certain degree roughness, which is caused by the additive manufacturing process resulting in small deviations from an exact round or elliptical cross-section. However, since the lattice structure is designed to increase the surface area, the roughness serves this purpose by further increasing the surface area of the lattice structure.

[0024] Preferably, the layers have a different number of lattice elements and / or different shaped lattice elements and / or differently arranged lattice elements. Alternatively, the lattice elements of at least two and preferably all layers are identically shaped, i.e. may have the same cross section and / or may be all shaped as helical wires, and the layers may only differ in the number of lattice elements and / or distance therebetween.

[0025] Preferably, the lattice structure comprises a plurality of groups of layers, wherein each group comprises at least two layers, wherein in each layer of one group the same number of lattice elements are present. For example, the lattice structure may comprise three groups of layers, wherein in the direction starting from the vacuum structure in the first group eight layers are present, wherein each layer has between 8 and 16 lattice elements. For example, each layer may have 12 wires, wherein these wires are alternating clockwise and counter-clockwise helically shaped from one layer to the next within the first group. Further, the lattice structure may have a second group of layers comprises again 8 layers, wherein each layer may comprise 16-32 lattice elements. For example, each layer of the second group of layers comprises 24 wires, which are alternating arranged clockwise and counterclockwise from one layer to the next layer. In addition, the lattice structure may comprise a third group of layers containing four layers, wherein each layer comprises 24-48 lattice elements. For example, in each layer of the third of group layers 36 clockwise and counterclockwise helical shaped wires are arranged combinedly in each layer. By adaption of the number of lattice elements, the porosity of the lattice structure can be adapted. At the same time the lattice structure can be formed optically blind, improving the trapping of gas particles inside the volume of the lattice structure and increasing the effect of radiative heating. Of course, other configurations are also possible having more groups of layers or less groups of layers and also the configuration of individual layers of each group can be different as well as the number of layers in each group may be different. In particular, also the given numbers for the lattice elements of each layer in each of the groups are only examples and the present invention is not limited to these specific numbers.

[0026] Preferably, by the lattice structure a vacuum component is provided. In particular, the lattice structure comprises an overall shape to provide the functionality of the vacuum component. Therein, the vacuum component comprises a first functionality within the vacuum and a pumping action by the NEG material of the lattice structure as second functionality. Thus, the vacuum component simultaneously provides the first functionality and the second functionality of a pumping action by the NEG material from which the vacuum component is made of. Hence, the vacuum component itself residing in a vacuum chamber of the vacuum apparatus serves as NEG element increasing thereby the surface of the exposed NEG material in the vacuum chamber without occupying additional space within the vacuum. The vacuum component must be present anyway depending on the respective application. Hence, the vacuum component is further utilized as NEG pump since it is fabricated from an NEG material by the additive manufacturing process. At the same time, while conventional vacuum components reduce the vacuum in the vacuum chamber due to outgassing, the vacuum components according to the present invention mitigate this effect. Due to use of the NEG material for the vacuum components, outgassing is prevented and the vacuum components even may provide a net pumping effect. Preferably, the vacuum component is one of a pipe, a manipulator, a source holder, a crucible, optics such as electron optics, charged particle optics, a heat shield, a wire sheath, a fastener, a platform, a viewport shutter, a depo-sition stage, an analytical stage, a wobble stick, a sample transfer arm, a port aligner, an aperture, an orifice or the like providing the first functionality. Thus, the vacuum component provides a common functionality to be operated in the vacuum. In addition, as described before, the vacuum component is made from an NEG material and thus provides a pumping action. In another aspect of the present invention an NEG cartridge is provided, in particular for an NEG pump. The NEG element comprises a base element as vacuum structure, wherein the base element has an opening to receive a heater, and a lattice structure as described before at least partially surrounding the base element. In particular, the opening extends through the whole base element or at least partially into the base element along the axial direction of the base element. Further, a lattice structure at least partially, and preferably fully, surrounds the base element. Preferably, the base element is in the center of the lattice structure. In particular, the lattice structure surrounds the lateral surface of the preferably cylindrical base element and may in some embodiments extend at least at one end beyond the axial end of the cylindrical base element. In particular, if the opening of the base element is built as blind hole, the lattice structure may extend beyond the axial end of the base element of a side, which does not contain the opening of the blind hole. Hence, the heater can be inserted into the base element from the other side.

[0027] Preferably, the base element and the lattice structure is made from the same material. Hence, the NEG cartridge is completely made of one single material and thus also the base element together with the lattice structure act as getter material.

[0028] Preferably, the NEG cartridge contains a base plate, wherein the base plate is arranged at an axial end of the base element, wherein the base element extends in particular perpendicular from the base plate. Therein, the base plate may serve as building platform and provides structural stability of the lattice structure. Hence, handling of the NEG cartridge is simplified and the NEG cartridge can be implemented into the existing NEG pumps replacing conventional disk cartridges of the prior art. Therein, the base plate may be shaped and adapted in order to fit into existing NEG pumps. In particular, the base plate is made from the same material as the lattice structure and thus contributes with its surface to the overall pump performance of the NEG cartridge.

[0029] Preferably, the NEG cartridge has a symmetry axis coinciding with the axial axis of the NEG cartridge or the axial axis of the base element.

[0030] Preferably, the base element as well as the lattice structure are built or made by additive manufacturing such as direct metal laser sintering (DMLS) or the like. In particular, the base element as well as the lattice structure are fabricated in the same fabrication step, i.e. by a layer-by-layer fabrication according to the additive manufacturing. If the NEG cartridge comprises a base plate, also the base plate is built by additive manufacturing and may be built in the same fabrication step as the base element and / or the lattice structure.

[0031] Preferably, the base element and the lattice structure are integrally built. In particular, the base element and the lattice structure are built as one piece. If the base element and the lattice structure are built by additive manufacturing, the structural elements are connected to each other and integrally fabricated in order to provide structural stability. In addition, if the NEG cartridge comprises a base plate, also the base plate may be integrally built with the base element and / or the lattice structure in particular in order to provide structural stability to the lattice structure or the NEG cartridge. Thus, the whole NEG cartridge may be a single piece.

[0032] Preferably, the porosity changes in a radial direction and preferably decreases in the radial direction.

[0033] Preferably, the NEG cartridge comprises a plurality of radially extending heat fins, which are connected to the base element. Preferably, the plurality of radially extending heat fins extend along the complete axial length of the base element or at least along a part of the axial length of the base element. In particular, the radially extending heat fins extend from one end of the cylindrical base element to the opposite axial end of the base element. In particular, if a base plate is present, the heat fins may extend from the base plate in the axial direction and more particularly may extend substantially perpendicular from the base plate. By the heat fins, heat of the heater that is inserted into the opening of the base element is efficiently conducted into the lattice structure thereby improving homogeneity of the heat in the lattice structure and providing efficient reactivation or activation of the NEG material of the lattice structure.

[0034] In particular, the heat fins are extending in a substantial radial direction. Thus, the heat fins are forming a star with the spikes of the star extending towards the radial outer surface of the lattice structure and in particular completely from the base element to the radial outer surface of the lattice structure. Alternatively, the heat fins are wound in a spiraling manner and thus have a radial component as well as a tangential component of their extension. In particular, by the spiraling heat fins a galaxy shape structure is formed, wherein the galaxy arms are formed by the heat fins. Consequently, a homogenous distribution of the heat is provided. At the same time an optically blind structure can be provided, in particular if the combined circumferential extension of the heat fins is larger than 180° and preferably 360° or larger.

[0035] Preferably, the transversal width of the heat fins decreases from the base elements towards the outer surface of the lattice structure. Consequently, the cross-section of the heat fin decreases and is larger close to the center of the lattice structure and smaller towards the outer part of the lattice structure. Thus, more heat is conducted closer to the center and less heat is conducted by the outer parts of the heat fins according to the specific requirements of heat in the specific parts of the lattice structure.

[0036] Preferably, the heat fins are made from the same NEG material as the lattice structure.

[0037] In particular, the heat fins are built by additive manufacturing at the same time the lattice structure and / or the base element is built.

[0038] In particular, the base element, the lattice structure and the heat fins are integrally built in particular as one piece.

[0039] In particular, the heat fins are made from Ti, Ti64 or another Ti alloy.

[0040] Preferably, the maximum distance of any point of the lattice structure to one of the heat fins is smaller than 5cm, preferably smaller than 3cm and more preferably smaller than 2cm. Hence, the maximum distance of any point of the lattice structure is small such that each point of the lattice structure can be sufficiently heated by the heat fins due to the close distance between any point of the lattice structure and the heat fins conducting the heat from the base element towards the outer parts of the lattice structure.

[0041] In another aspect of the present invention an NEG pump is provided comprising an NEG cartridge as described before and a heater extending into the opening of the base element to reactivate or activate the NEG material of the lattice structure. Preferably the heater is rod shaped. Preferably, the heater is a ceramic and / or resistive heater. Preferably, the opening has a size conforming with the size of the heater such that close contact between the base element and the heater is provided.

[0042] In another aspect of the present invention an NEG pump is provided comprising an NEG element as described before and a heater connected to or in direct / indirect contact with the NEG material of the NEG element to reactivate or activate the NEG material of the lattice structure. Preferably the heater is rod shaped. Preferably, the heater is a ceramic and / or resistive heater.

[0043] Hence, by the NEG cartridge according to the present invention an improved NEG cartridge is provided which can replace existing and conventional NEG cartridges comprising disk shaped NEG elements. Therein, by the lattice structure made from the NEG material, improved pump performance is provided compared to conventional disk shaped NEG elements.

[0044] In the following the present invention is described in more detail with reference to the accompanying figures.

[0045] The figures show:

[0046] Figures 1A, 1 B embodiments of an NEG element according to the present embodiments

[0047] Figures 2A, 2B other embodiments of an NEG element according to the present invention

[0048] Figure 3 another embodiment of an NEG element as vacuum component according the present invention

[0049] Figure 4 a first embodiment of an NEG cartridge according to the present invention, Figures 5A, 5B a detailed view of the lattice structure according to the present invention,

[0050] Figure 6A, 6B another detailed view of the lattice structure according to the pre- sent invention,

[0051] Figure 7A a top view of the schematic NEG cartridge comprising layers,

[0052] Figure 7B a view of the schematic NEG element comprising layers,

[0053] Figure 8A a top view of the schematic NEG cartridge comprising groups of layers,

[0054] Figure 8B a view of the schematic NEG element comprising groups of lay- ers,

[0055] Figure 9A, 9B an embodiment of an NEG cartridge comprising heat fins in a first embodiment and

[0056] Figure 10A, 10B comprising heat fins in a second embodiments.

[0057] Referring to Figure 1 showing an NEG element in particular for an NEG vacuum pump. The NEG element comprises a lattice structure 18 connected to a surface 118 of a vacuum structure 100. The vacuum structure 100 may be any component of a vacuum apparatus such as a chamber wall, a vacuum pipe, a deflector plate, a pipe connection, a part of a flange, a base element of an NEG cartridge or the like. In Figure 1 the vacuum structure 100 is shown as flat element having a flat surface 118. However, the vacuum structure 100 may provide alternatively a bended surface, a rounded surface or an arbitrarily shaped surface to which the lattice structure 38 is connected. In particular, the lattice structure 38 is manufactured to adapt to the shape of the surface 118 of the vacuum structure 100. The lattice structure 38 is considered an arrangement of lattice elements 110 in a regular, repeating geometric pattern extending in two or three dimensions, which defines the spatial organization of the NEG material. The lattice structure 18 in the example of Figure 1A and 1 B comprises a plurality of wires 112, 114 as lattice elements arranged in a perpendicular manner to each other to create the lattice structure 18. Therein, the lattice elements 110 are stacked on top of each other in an alternating manner, wherein a pair 116 of perpendicular wires 112, 114 are repeated in a direction away from the surface 118 of the vacuum element 100, in particular in a direction perpendicular to the surface 118 of the vacuum element 100. The lattice structure 18 is built by additive manufacturing and in particular DMLS. Therein, the lattice structure 18 and the vacuum structure 100 may be built during the same fabrication step. In particular, the vacuum structure and the lattice structure 18 may be built from the same material. Alternatively, the lattice structure 18 can be manufactured separate from and distant of the vacuum structure 100 and subsequently attached to the vacuum structure 100 by fixing means, soldering, brazing, welding, clamping or the like.

[0058] The lattice structure 18 is built from an NEG material, which provides getter activity in order to provide a pumping action of the NEG cartridge. Therein, the lattice structure 18 is built from titanium (Ti), Ti64 or another Ti alloy. It has been shown that these materials can be used in an additive manufacturing process such as DMLS and at the same time, after activation, are able to act as NEG material.

[0059] As shown in Figure 1A, 1 B, the lattice structure 18 is built as periodic pattern providing a small filling factor. In particular, the volume filling factor of the lattice structure 18 is less than 25% and preferably less than 15%. At the same time, due to the lattice structure 18, the surface of the NEG material provided by the lattice structure 18 is increased, increasing the pump performance of the NEG element. Further, the lattice structure 18 is optically blind. This means that no straight line can be drawn from the outer surface 120 of the lattice structure 18 to the vacuum structure 100, i.e. the surface 118 of the vacuum structure 100, or in a tangential direction parallel to the surface 118 through the lattice structure 18. Hence, due to the open structure of the lattice structure 18 gas particles can easily enter into the lattice structure 18 and are trapped within the volume. Thus, by the lattice structure 18 likelihood of a collision of the gas molecules with a surface of the NEG material provided by the lattice structure 18 is enhanced. Consequently, the pump performance is improved. Therein, the porosity of the lattice structure 18 can be tailored to the specific needs thereby maximizing the parameters of surface of the lattice structure, trapping ability for gas particles, which already have entered the lattice structure and the ability of gas particles entering the lattice structure.

[0060] Although shown in Fig. 1A, 1 B that the lattice structure 18 may be built from straight wires 112, 114 as lattice elements 110, the present invention is not limited to this embodiment and the lattice elements 110 may have any shape, such as a helical shape (as described in more detail below), round shape, circular shape, bended shape, wavy shape, or the like. Further, arrangement of the wires 112, 114 relative to each other can be adapted accordingly to be arranged in an angle to each other or in an angle relative to the surface 118 of the vacuum structure. In particular, due to use of additive manufacturing for creating the lattice structure 18, there is a high degree of freedom regarding the shape of the lattice elements 110 constituting the lattice structure 18.

[0061] In the embodiments of Figures 2A, 2B, the vacuum structure is provided by a pipe. Therein, as shown in Figures 2A, 2B, the lattice structure can accommodate the shape of the pipe. In Figure 2A the lattice structure is inserted into a space between an inner pipe 122A and an outer pipe 122B, thereby surrounding an inner space 124. In Figure 2B, the complete pipe 122 is filled by the lattice structure 38. Therein, the lattice structure 38 can be fabricated separate of the pipes 122, 122A, 122B and then inserted in to the respective space. Alternatively, the pipes 122, 122A, 122B may be produced also by additive manufacturing together with the lattice structure 38 in particular in a layer-by-layer manufacturing process.

[0062] Figure 3 shows a vacuum component built by the lattice structure 18. Therein, in the example of Figure 3, the vacuum component is shown as sample holder holding a sample 126. However, the present invention is not limited to a sample holder and the vacuum component built by the lattice structure 18 may be one of a pipe, a manipulator, a source holder, a crucible, optics such as electron optics, charged particle optics, a heat shield, a wire sheath, a fastener, a platform, a viewport shutter, a deposition stage, an analytical stage, a wobble stick, a sample transfer arm, a port aligner, an aperture, an orifice or the like providing a functionality within the vacuum. Thus, the vacuum component provides a common functionality to be operated in the vacuum. In addition, the vacuum component is made by the lattice structure 18 from an NEG material and thus provides a pumping action. Referring to Figure 4 showing an NEG cartridge 10 in particular for an NEG vacuum pump. The NEG cartridge 10 comprises a cylindrical base element 12 as vacuum structure. The base element 12 comprises an opening 14 which is configured to receive a heater and in particular a rod shaped heater such as a resistive heater for activation and reactivation of the NEG cartridge 10. The base element 12 is surrounded by the lattice structure 18. Structural stability is further provided by a base plate 16 which is connected to an axial end of the base element 12, wherein the base element 12 extends in particular perpendicular from the base plate 16. Therein, the lattice structure 18 as well as the base element 12 are built by additive manufacturing and in particular DMLS. Therein, the lattice structure 18 and the base element 12 may be built during the same fabrication step. In particular, the base element 12 and the lattice structure 18 are built from the same material. The lattice structure 18 is built from an NEG material, which provides getter activity in order to provide a pumping action of the NEG cartridge. Therein, the lattice structure is built from titanium (Ti), Ti64 or another Ti alloy. It has been shown that these materials can be used in an additive manufacturing process such as DMLS and at the same time, after activation, are able to act as NEG material. In the case that the NEG cartridge 10 contains a base plate 16, also the base plate 16 can be built by additive manufacturing together with the lattice structure 18 and / or the base element 12. Alternatively, the base plate 16 can be provided as a building platform for the base element 12 and / or the lattice structure 18. In particular, the whole NEG cartridge 10 may be a single piece which is robust and easy to handle compared to sintered metal disks of conventional NEG cartridges.

[0063] Therein, the NEG cartridge 10 of the present invention may be configured such that it may replace NEG cartridges of existing NEG vacuum pumps comprising NEG elements that are disk shaped which only provide an inferior pumping activity compared to the NEG cartridge 10 of the present invention.

[0064] In the following it is referred to Figures 5A and 5B. In the Figures 5A and 5B for simplicity only individual lattice elements 20, 22 are shown for the example of the NEG cartridge, wherein the vacuum structure is provided by the base element 12. Therein, the lattice elements 20, 22 are provided in the shape of clockwise or counter-clockwise helically shaped wires winding in particular around the cylindric base element 12. Therein, as indicated in Figure 7A the individual lattice elements are arranged in radial layers 32. The lattice elements 20, 22 in each layer 32 may be identical or almost identically shaped. Therein, the lattice elements of adjacent layers may be differently shaped or identically shaped. As shown in Figure 5A in a first layer 32 a first lattice element 20 is arranged which is in direct contact with the base element 12. Figure 5A shows a second lattice element 22 is provided which is arranged in an adjacent or second layer 32 and thus the second lattice element 22 is radially distant or apart from the lateral surface of the cylindrical base element 12. In Figure 7B the layers 32 are arranged in a stacked manner on top of each other and substantially parallel to the surface 118 of the vacuum structure 100. The lattice elements 110 in each layer 32 may be identical or almost identically shaped. Therein, the lattice elements 110 of adjacent layers may be differently shaped or identically shaped. Therein, as shown in Figure 1 , in a first layer 32 a first lattice element 114 is arranged which is in direct contact with the surface 118 of the vacuum structure 100. Figure 1 shows a second lattice element 112 that is provided which is arranged in an adjacent or second layer 32 and thus the second lattice element 112 is distant or apart from the surface 118 of the vacuum structure 100.

[0065] Therein, adjacent layers may overlap by more than 2% and preferably more than 5% and more preferably by more than 10%. Due to the overlap at the crossing point 23 (see Figure 5A) of the first lattice element 20, 114 and the second lattice element 22, 112 of adjacent layers 32, structural and thermal connection is established which, on the hand provides structural stability of the overall lattice structure 18 and, on the other hand enables heat conductance across the lattice structure 18 from the vacuum structure 100 or base element 12 towards the outer parts of the lattice structure 18.

[0066] In Figures 6A, 6B the clockwise lattice element 20 and the counterclockwise lattice element 22' are arranged in the same layer such that at the crossing point 23 a full overlap between the first lattice element 20 and the second lattice element 22' exists. Hence, one layer may comprise more than one lattice element as building block increasing the freedom of design for the lattice structure 18

[0067] Therein, the directions "clockwise" and "counter-clockwise" are defined when viewed from above along the axial axis of the base element 12 or the cartridge 10 in Figures 5A, 5B, in a direction from the top surface 120 towards the surface 118 of the lattice structure 120 in Figures 1 A, 1 B or along the axial axis of the pipe 22 in Figures 2A, 2B Figure 8Aand 8B shows a schematic structure of the lattice structure 18 comprising a plurality of groups of layers 34, wherein each group comprises at least two layers 32 as exemplified in Figure 7A and 7B, respectively. Therein, each layer 32 of one group 34 may have the same number of lattice elements. Thus, a first group 34 may have 12 instances of lattice elements each, wherein each layer 32 of a second group 34 may have 24 instances and a third group 34 may have 36 instances of lattice elements. Therein, the lattice elements may also be clockwise and / or counterclockwise helically shaped wires as exemplified in Figures 5A, 5B and Figures 6A, 6B. Thus, by arranging the layers 32 into a plurality of groups 34 of layers, porosity of the lattice structure 18 can be adapted to the specific needs of the application. At the same time, despite a regularly patterned lattice structure being provided, due to the plurality of groups 34 an optically blind lattice structure 18 can be provided.

[0068] In the following it is referred to Figures 9A and 9B. In this embodiment the NEG cartridge 10 comprises a plurality of heat fins 36 which are radially extending from the base element 12 in a star like manner. By the heat fins 36 heat from the base element 12 is conducted towards the outer most parts of the lattice structure 18. Therein, the lateral width of the respective heat fins may decrease towards the outer surface of the lattice structure 18 in accordance with the heat requirement to be conducted from the heater arranged in the central opening 14 (Figure 4) towards the outer parts of the lattice structure 18.

[0069] In Figures 10A and 10B another embodiment is shown, wherein the heat fins 36' are shaped spiraling or in a winding manner. Therein, the cross-section has a galaxy shape, wherein the arms of the galaxy are provided by the heat fins 36'. Also in the embodiment of Figures 10A and 10B the lateral cross-sections of the heat fins are decreasing towards the outer surface in accordance with the requirement of heat conductance. Thus, the volume occupied by the lattice structure 18 can be maximized. Therein, the heat fins 36 in the embodiment of Figures 10A and 10B extend for an angle of about 360° providing an optical blind NEG cartridge.

[0070] In the embodiments of Figures 9A, 9B and 10A, 10B, the heat fins 26 may extend at least partially and preferably along the whole axial length of the base element. In the case a base plate is present, the heat fins 36 may extend from the base plate 16 and in particular extend substantially perpendicular from the base plate 16. Therein, the heat fins 36, 36' are also fabricated by an additive manufacturing process. In particular, also the heat fins 36, 36' are fabricated in the same process as the lattice structure 18 and / or the base element 12. Therein, preferably also the heat fins 36, 36' are made from the same material as the lattice structure 18, i. e. preferably Ti, Ti64 or another Ti alloy and thus also contribute to the pump performance of the NEG cartridge with their surfaces.

[0071] In addition, in the embodiments of Figures 9A, 9B and 10A, 10B, the maximum distance of any point of the lattice structure to one of the heat fins 36, 36’ is small increasing the efficiency of heating of the lattice structure 18 either by heat conductance via the crossing points 23 in the lattice structure 18 or via heater radiation.

[0072] Reference List

[0073] 10 NEG cartridge

[0074] 12 base element

[0075] 14 opening

[0076] 16 base plate

[0077] 18 lattice structure

[0078] 20 lattice element

[0079] 22, 22’ lattice element

[0080] 23 crossing point

[0081] 32 layer

[0082] 34 group of layers

[0083] 36, 36’ heat fin

[0084] 100 vacuum structure

[0085] 110 lattice elment

[0086] 112 wire

[0087] 114 wire

[0088] 116 pair

[0089] 118 surface

[0090] 120 surface

[0091] 122 Pipe

[0092] 122A, 122B Pipe

[0093] 124 inner space

[0094] 126 sample

Claims

CLAIMS1. NEG element, in particular to be attached or inserted into a vacuum structure, comprising a lattice structure, wherein the lattice structure is made from an NEG material.

2. NEG element according to claim 1 , wherein the lattice structure is built by additive manufacturing.

3. NEG element according to claim 1 or 2, wherein the lattice structure is manufactured on the vacuum structure or separate of the vacuum structure.

4. NEG element according to any of claims 1 to 3, wherein the lattice structure is optically blind.

5. NEG element according to any of claims 1 to 4, wherein the lattice structure has a volume filling factor of less than 25% and preferably less than 15%.

6. NEG element according to any of claims 1 to 5, wherein the lattice structure is made from Ti, Ti64 or another Ti alloy.

7. NEG element according to any of claims 1 to 6, wherein the porosity changes in a direction substantially perpendicular to a surface of the vacuum structure and preferably decreases in the direction.

8. NEG element according to any of claims 1 to 7, wherein the lattice structure comprises a plurality of layers, wherein in each layer substantially identical lattice elements are used to create the lattice structure.

9. NEG element according to claim 8, wherein adjacent layers overlap by more than 2%, preferably by more than 5% and more preferably by more than 10% to create a structural and thermal connection between the lattice elements of the adjacent lay- ers.

10. NEG element according to claim 8 or 9, wherein one or more layers comprise as a lattice element a clockwise and / or counter-clockwise helically shaped wire.

11. NEG element according to claim 10, wherein the wire is elliptical, wherein preferably the long axis of the ellipse extends tangentially and the short axis extends radially.

12. NEG element according to any of claims 8 to 11 , wherein the lattice structure comprises a plurality of groups of layers, wherein in each layer of one group the same number of lattice elements are present.

13. NEG element according to any of claims 1 to 12, wherein by the lattice structure a vacuum component is provided.

14. NEG cartridge comprising, in particular for an NEG pump, comprising: a base element, wherein the base element has an opening to receive a heater, a lattice structure according to any of claims 1 to 12 at least partially surrounding the base element.

15. NEG cartridge according to claim 14, wherein the base element and the lattice structure are integrally built.

16. NEG cartridge according to claim 14 or 15, wherein the base element is built by additive manufacturing.

17. NEG cartridge according to any of claims 14 to 16, wherein a plurality of radially extending heat fins is connected to the base element.

18. NEG cartridge according to claim 17, wherein the heat fins are extending in the radial direction or wound in a spiraling manner.

19. NEG cartridge according to claim 17 or 18, wherein the maximum distance of any point of the lattice structure to one of the heat fins is smaller than 5 cm, preferably smaller than 3 cm and more preferably smaller than 2 cm.

20. Vacuum pump, in particular NEG vacuum pump, comprising an NEG element according to any of claims 1 to 13 or an NEG cartridge according to any of claims 14 to 19 and a heater in particular extending into the opening of the base element to reactivate or activate the NEG material of the lattice structure.

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