Clamping device for at least one filament and mass spectrometer

Abstract

The present invention relates to a clamping device (1) for at least one filament, comprising: at least one filament receptacle (2a, 2b) for receiving at least one filament. The clamping device (1) is designed for detachable attachment, in particular clamping attachment, of at least one filament receptacle (2a, 2b) to a container (7) of an ionization device. The present invention also relates to a mass spectrometer, comprising: an ionization device having a container (7) in which an ionization space for ionizing a gas is formed; at least one clamping device (1) designed for detachable attachment, in particular clamping attachment, of at least one filament receptacle (2a, 2b) to the container (7); and a vacuum housing to which the clamping device (1), in particular the base body (4) of the clamping device (1), is detachably connected. The clamping device (1) is designed to exert a clamping force on at least one filament receptacle (2a, 2b) in the installed position in order to press the at least one filament receptacle (2a, 2b) against the container (7).

Description

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a clamping device for at least one filament, comprising: at least one filament receptacle for receiving (and clamping) at least one filament, and a mass spectrometer having at least one such clamping device.

[0003] The filament (heated filament) is used in an ionization device to ionize a gas, for example, it can be used in a mass spectrometer for trace analysis. In electron ionization, the filament (heated filament) is heated to a high temperature in order to generate an electron beam through the thermoelectric effect, and the electron beam hits the gas to be ionized and ionizes it.

[0004] For the replacement of filaments in such electron ionization devices, it is usually necessary to remove the entire ionization device (i.e., the inlet or inlet system, the container having the ionization volume and extraction optics) from the mass spectrometer in order to be able to subsequently replace the filament(s). This process is very time-consuming and requires breaking the vacuum. However, in certain applications of mass spectrometry, such as in process monitoring, the high time consumption during filament replacement is intolerable.

[0005] OBJECT OF THE INVENTION

[0006] The object of the present invention is to provide a clamping device for at least one filament and a mass spectrometer which allow for the rapid exchange of (at least) one filament.

[0007] SUBJECT MATTER OF THE INVENTION

[0008] This object is achieved by a clamping device of the type mentioned at the beginning, which is designed for the detachable attachment of the filament receptacle, in particular for clamping attachment to the container of the ionization device. The clamping device is designed to detachably attach the filament receptacle to the container, usually in an installation position in which the filament feeds or can feed an electron beam into an ionization space formed in the container.

[0009] According to the invention, it is proposed that the clamping device for at least one filament or the filament receptacle be mechanically separated from the container of the ionization device in which the ionization space is formed. Thus, the filament(s) is / are not directly mounted on the container or the ionization device, but are placed on or attached to a separate filament receptacle, which in turn is detachably fastened to the container. Each filament receptacle usually has only one filament, which is positioned (clamped) at a predetermined installation position on the container. The filament receptacle(s) is / are usually clamped to the container for detachable attachment, i.e., the clamping device is designed to exert a clamping force on the filament receptacle(s) in the installation position in order to press it / them against the container.

[0010] At the installation location, the filament receptacle abuts the container or the housing of the ionization device. To prevent the filament receptacle from slipping off at the installation location, the filament receptacle may have one or more protrusions that engage in one or more recesses (e.g., in the form of grooves) on the container of the ionization device in the installation position, or vice versa.

[0011] In one embodiment, the clamping device includes a base body that is connected to at least one filament receptacle via at least one connecting element. The base body is generally designed to be detachably fastened to the (vacuum) housing of the mass spectrometer to allow access to the filament receptacle(s) during filament replacement by removing the base body or the entire clamping device from the housing of the mass spectrometer.

[0012] The base body may have a flange portion or form a flange that is generally orthogonally aligned with the main axis or central axis of the container or ionization device and is connected (usually by threading) to the housing of the mass spectrometer via the flange. At least one filament receptacle connected to the base body via the connecting element can also be removed from the ionization device through the opening in the housing that becomes free when the base body is removed. If the base body is installed at a predetermined installation position on the housing of the mass spectrometer, e.g., by a flange connection or a threaded connection, the filament receptacle is also clamped in a predetermined installation position relative to the container by means of the connecting element and is thus clearly positioned relative to the container. In particular, the connecting element can be used to generate a clamping force or pressure on the filament receptacle arranged in the clamping position or to transmit it to the filament receptacle.

[0013] In a development, the connecting element is designed as an elastic element, in particular a leaf spring. In this case, the connecting element itself is used to apply a clamping force to at least one filament receptacle because the connecting element is deflected from its basic position in the installation position and exerts a force on the filament receptacle.

[0014] In an alternative development, the connecting element is designed to be rigid, and a pre-tensioning element engages with the connecting element to apply a clamping force to the filament receptacle. In this case, the connecting element itself is not used to apply a clamping force to the filament receptacle, but rather to transmit the clamping force from the (mechanical) pre-tensioning element to the rigid connecting element.

[0015] In a further development, the base body has a linear guide for guiding the connecting element, which linear guide can form a sliding feedthrough, for example. The connecting element can be displaced relative to the base body along the linear guide. In this case, the connecting element and thus the filament receptacle are clamped in the installed position against the action of a pre-tensioning force, which pre-tensioning force generally acts parallel to the direction in which the connecting element can be displaced. When the clamping device is inserted into the mass spectrometer, the connecting element is generally displaced from a basic position in which the pre-tensioning element does not exert any pre-tensioning force on the connecting element, against the action of the pre-tensioning force when the filament receptacle abuts against the container. Thus, in the installed state of the clamping device, i.e., after the base body of the clamping device has been fixed to the housing of the mass spectrometer, the pre-tensioning element exerts a clamping force on the filament receptacle. For the detachable clamping of the filament receptacle on the container, the clamping device can also have a sliding feedthrough instead of the linear guide.

[0016] In an alternative embodiment, the connecting element forms a pivotable arm which is connected to the base body via a swivel joint. When the clamping device is inserted into the vacuum housing, once the filament receptacle abuts against the container, the connecting element generally pivots or deflects about the axis of rotation from the basic position against the action of the pre-tensioning force. In the installed position, i.e., after the base body of the clamping device has been fixed on the vacuum housing, the filament receptacle is pressed against the container against the action of the pre-tensioning force. The pivotable arm can in particular form a double-sided lever, on the first lever arm of which the filament receptacle is rigidly fastened. The pre-tensioning element generally acts on the second lever arm.

[0017] In a further development, the pre-tensioning element is designed as a spring element which is preferably connected on the one hand to the base body and on the other hand to the connecting element. For the above case where the base body has a linear guide for the connecting element, the spring element can be a compression spring, for example. In this case, when the clamping device is introduced into the ionization device, the filament receptacle is displaced together with the connecting element against the action of the compression spring such that the filament receptacle exerts a clamping force on the container in its installed position. For the above case where the filament receptacle is attached to a connecting element in the form of a pivotable arm which forms a double-sided lever, one end of the spring element can be connected to the second lever arm and the other end can be connected to the base body.

[0018] The clamping device preferably has two connecting elements in the form of pivotable arms, each of which is connected to the base body via a swivel joint. In this case, a separate filament receptacle is fastened to each of the two pivotable arms. This embodiment is particularly advantageous in the case where two (or possibly more than two) filament receptacles are detachably attached or fastened to opposite sides of the container and are to be clamped. The use of two separate swivel joints and the attachment of the two pivotable arms to the same base body has proven to be advantageous for the application of the clamping force, which will be described in more detail below.

[0019] In a further development variant, the pretensioning element is designed to pivot two pivotable arms in opposite directions (i.e. opposite rotational directions) about each swivel joint, in order to fasten two filament receptacles attached to the pivotable arms in a clamping manner on two opposite sides of the container. For this purpose, the pretensioning element generally acts on two first lever arms of the pivotable arms or on two second lever arms of the pivotable arms in order to pivot them towards or away from each other. In order to pivot the two pivotable arms relative to the container in a pair of pliers-like (symmetrical) manner, the pretensioning element engages at the same distance from the respective axis of rotation on the respective (first or second) lever arm of the pivotable arm. The clamping device, more precisely the connecting element and the filament receptacle, can in particular be arranged mirror-symmetrically with respect to a symmetry plane or a symmetry axis. The symmetry plane or symmetry axis intersects the central axis of the container.

[0020] The advantage of clamping the container from both sides (symmetrically) is that in this way shear forces which could displace the main axis of the container are prevented. Since the container or the ionization device does not have to be removed for filament replacement, the optimized positioning of the main axis of the container is thus maintained. The inlet or inlet opening for supplying the gas to be ionized to the ionization space and the outlet for the ionized gas generally run along the main axis of the container. The container is generally substantially radially symmetric about the main axis, i.e. it has a cylindrical basic shape, the cylindrical axis of which forms the main axis of the container.

[0021] In a further embodiment, the pretensioning element is designed to be rigid, in particular rod-shaped, is guided in a guide rail of a base body, in particular in a linear guide, and has a free end which has an abutment surface for abutting against the container. In this case, when the clamping device is introduced into the housing, the pretensioning element moves along the guide rail as soon as the abutment surface abuts against the container. The movement along the guide rail has the effect that the pretensioning element acts on the connecting element in order to transmit the clamping force to the connecting element. It has proven to be advantageous in this case if the pretensioning element is guided in a linear guide so as to be linearly displaceable. The displacement direction of the pretensioning element is preferably oriented perpendicular to the central axis of the container.

[0022] In a further development variant, the pretensioning element has a guide element which engages two pivotable arms. Generally speaking, in this case the entire pretensioning element moves along the guide rail and the guide element, in the form of a bolt, a pin or the like for example, is coupled to the respective lever arms of the two pivotable arms in order to pivot them about the respective axis of rotation and to exert a clamping force on the filament receptacle(s) or the container in the installed position of the clamping device. The coupling of the guide element to the two pivotable arms can be effected, for example, by means of elongated holes made in the first or second lever arm of the pivotable arm. It goes without saying that the guide element can also be coupled to the pivotable arms in another way.

[0023] Another aspect of the present invention relates to a mass spectrometer, which comprises: an ionization device having a container in which an ionization space for ionizing a gas is formed; at least one clamping device designed as described above for detachably fastening at least one filament holder to the container, in particular by clamping; and a vacuum housing to which the clamping device, in particular the base body of the clamping device, is detachably attached. The base body of the clamping device usually has a flange portion and is detachably connected to the vacuum housing in its installed position, for example by a threaded connection. The clamping device or its base body is thus accessible to an operator located outside the vacuum housing to allow the exchange of one or more filaments.

[0024] In the case where the clamping device has two (or possibly more) filament holders for clamping two (or possibly more) filaments, the ionization device can operate redundantly: Only when both filaments fail is it necessary to replace the filaments or remove the clamping device. However, the mass spectrometer can also have two or more clamping devices that are fastened to the vacuum housing via separate base bodies or flanges, which are arranged, for example, orthogonally to each other or opposite to each other with respect to the container. In this case, once one of the filaments fails, the corresponding clamping device can be released from the vacuum housing. However, in this case, at least two separate access ports or openings are required in the vacuum housing to ensure redundancy.

[0025] Through the access port or opening in the vacuum housing, the clamping device together with the filament holder(s) can be removed from the vacuum housing, and the filament can be replaced without removing the container or the ionization device as a whole from the vacuum housing and repositioning it in the vacuum housing after the filament exchange. This is particularly advantageous when the ionization device or its container / housing is directly connected to an ion transfer component (such as a transfer quadrupole, etc.) or even screwed onto it.

[0026] When removing the clamping device from the vacuum housing, the vacuum must be broken. To ensure rapid filament replacement, an inert gas (e.g., (dry) nitrogen or a noble gas) is used to ventilate the vacuum housing. In this way, the pumping time after filament replacement can be reduced because pumping out the water deposited on the inner wall of the vacuum device during other ventilation periods is the most time-consuming step in the entire pumping process.

[0027] In an embodiment of the mass spectrometer, the pre-tensioning element of the rigidly designed clamping device is placed on the container with its abutting surface in the installed position. As further described in connection with a clamping device acting in a pliers-like manner, in this case, when the clamping device is inserted into the vacuum housing, the pre-tensioning element abuts against the container and presses the two filament holders fastened to the pivotable arms against opposite sides of the container with respect to the main axis of the container, or clamps them to the container. For this purpose, the flange portion of the base body is usually oriented orthogonally to the main axis or central axis of the container or the ionization device.

[0028] Further features and advantages of the present invention will become apparent from the following description of embodiments of the invention with reference to the drawings and from the claims, the drawings showing details which are essential to the present invention. In variants of the present invention, the individual features can each be implemented independently or jointly in any combination. Description of the Drawings

[0029] The embodiments are shown in schematic diagrams and are explained in the following description. In the drawings:

[0030] Figure 1 is a schematic illustration of a clamping device having two filament receptacles,

[0031] Figure 2 is a schematic illustration of a mass spectrometer having Figure 1 a clamping device for the clamping attachment or fastening of two filament receptacles to a container of an ionization device,

[0032] Figures 3a - 3c is Figure 1 a schematic illustration of the clamping device and the container to which two filament receptacles are fastened in a clamping manner, and

[0033] Figures 4a - 4c is a schematic illustration of a clamping device designed for the clamping attachment of a filament receptacle to a container.

[0034] In the following description of the drawings, the same reference numerals are used for the same or functionally identical components. Detailed Description of the Invention

[0035] Figure 1 The clamping device 1 is schematically shown, which includes two filament receptacles 2a, 2b for receiving (and for clamping) respective filaments 3a, 3b (see Figure 2 ), which are not shown in Figure 1 . In each case, the first filament receptacle 2a and the second filament receptacle 2b are connected to the base body 4 of the clamping device 1 via a first connecting element 5a and a second connecting element 5b. In the example shown in Figure 1 , the two connecting elements are each designed in the form of rigid pivotable arms 5a, 5b. The pivotable arms 5a, 5b are each connected to the base body 4 via their own rotary joints 6a, 6b.

[0036] Figure 2 The two filament receptacles 2a, 2b in the installation position of the clamping device 1 in the mass spectrometer 9 are shown. As Figure 2As shown, in the installation position of the clamping device 1, two filament holders 2a, 2b are placed on opposite sides of the container 7 of the ionization device 8, which forms part of the mass spectrometer 9. When the clamping device 1 is installed, due to the movement of the pincers of the two pivotable arms 5a, 5b, the two filament holders 2a, 2b are attached or fastened to the container 7 in a clamping manner.

[0037] In the example shown, the container 7 has a substantially cylindrical outer surface, and the filament holders 2a, 2b are adjacent to this outer surface. The pivotable arms 5a, 5b exert a clamping force on the filament holders 2a, 2b, as described in more detail below in connection with Figures 3a - 3c more detailed description.

[0038] Figure 2 The ionization device 8 of the mass spectrometer 9 shown has an inlet or inlet system 10 for feeding the gas 11 to be analyzed into the ionization space 12, which is formed in the container 7 of the ionization device 8. As is also visible in Figure 2 the first filament 3a generates an electron beam 13, which is fed into the ionization space 12 via a side opening in the container 7 and is used to generate the ionized gas 14 to be analyzed by electron impact ionization.

[0039] The mass spectrometer 9 also has an extraction device 15 in the form of an electrode arrangement to extract the ionized gas 12 from the ionization space 10 and accelerate the ionized gas 12 in the direction of the transfer quadrupole 16 and, if necessary, focus it before mass spectrometry in the detector 17 (e.g., in the form of a time-of-flight detector). In addition to transporting the ionized gas 14, the transfer quadrupole 16 can also be used for mass separation or mass selection. It goes without saying that Figure 2 the mass spectrometer 9 shown in should be understood as an example and can also be designed in other ways. For example, the mass spectrometer 9 can have other types of detectors 17, another type of ion transfer device, etc.

[0040] Figure 2 The mass spectrometer 9 shown in also has a vacuum housing 18 in the form of a stainless steel housing, in which the ionization device 8 and the container 7 are fixed. The ionization device 8 or the container 7 can in particular be screwed to other components of the mass spectrometer 9, for example screwed to the extraction device 15 or to the transfer quadrupole 16. The components or stages inside the vacuum housing 18 are differentially pumped by a vacuum pump (not shown). The interior of the vacuum housing 18 of the mass spectrometer 9 is not easily accessible to the operator from the outside.

[0041] However, in order to be able to exchange the filaments 3a, 3b quickly, the base body 4 of the clamping device 1 is fastened (usually by means of a thread) in its installation position in the mass spectrometer 1 via a detachable connection to the vacuum housing 18 of the mass spectrometer 9. In the example shown, the plate-shaped part 4a of the base body 4 lies on the outside of the vacuum housing 18 and is connected to the vacuum housing 18 by means of a flange connection or a threaded connection. In the installation position of the clamping device 1, the part 4b of the base body 4 protruding from the plate-shaped part 4a extends into the vacuum housing 18 of the mass spectrometer 9.

[0042] Thus, in order to exchange Figure 2 the two filaments 3a, 3b in the mass spectrometer 9 shown, it is not necessary to remove the ionization device 8, in particular the container 7, from the vacuum housing 18 of the mass spectrometer 9; rather, if the externally accessible part 4a of the base body 4 is removed from the vacuum housing 18 and the clamping device 1 is removed from the vacuum housing 18, the clamping of the two filament receptacles 2a, 2b is simply released.

[0043] In order to exchange the filaments 2a, 2b, the vacuum in the vacuum housing 18 must be broken. In order to avoid moisture deposition on the components located in the vacuum housing 18 or on the inside of the vacuum housing 18, the inside of the vacuum housing 18 is ventilated or purged with an inert gas (e.g., with (dry) nitrogen). In this way, the pumping time during subsequent evacuation of the vacuum housing 18 can be significantly reduced.

[0044] In order to reposition the clamping device 1 in the vacuum housing 18 after exchanging the filaments 2a, 2b, the protruding part 4a of the base body 4 together with the filament receptacles 2a connected to the base body 4 via two pivotable arms 5a, 5b is introduced into the vacuum housing 18 in the Figure 2 Z direction of the XYZ coordinate system shown, in particular via an inlet or opening in the vacuum housing 18 which is located above the main axis or central axis M of the ionization device 8 in the Z direction. In Figure 2 the mass spectrometer 9 shown, the plate-shaped part 4a of the base body 4 thus extends parallel to the XY plane, which corresponds to the drawing plane.

[0045] In order to press the two filament receptacles 2a, 2b against the outer surface or circumference of the container 7 such that they are fixed or clamped relative to the container 7 in a predetermined position, Figure 1 and Figures 3a - 3c the clamping device 1 shown in has a rigidly designed rod-shaped pre-tensioning element 20. The rod-shaped pre-tensioning element 20 extends along the symmetry axis S of the clamping device 1, which is perpendicular to the plate-shaped part 4a of the base body 4 and corresponds to the Z direction in the installation position of the clamping device 1 in the vacuum housing 18.

[0046] The rod-shaped pre-tensioning element 20 has an abutment surface 20a (see Figure 1), when the clamping device 1 is inserted into the vacuum housing 18, the abutment surface 20a is pressed against the container 7, more precisely against the outer surface of the container. The rod-shaped pre-tensioning element 20 is displaced along the symmetry axis S in a linear guide 21 (guide rail) formed in the protruding part 4b of the base body 4, and this symmetry axis S corresponds to the Z direction in the installation position of the clamping device 1. During the linear displacement of the pre-tensioning element 20 in the Z direction, the guide element 22 (in the example shown, a bolt) attached to the pre-tensioning element 20 is displaced in the direction of the plate-shaped part 4a of the base body 4, and the guide element 22 laterally protrudes through an elongated hole in the protruding part 4a of the base body 4.

[0047] The guide element 22 in the form of a protruding bolt engages with the two pivotable arms 5a, 5b. More precisely, the guide element 22 in the form of a bolt engages with two elongated holes 23a, 23b in the respective first lever arms of the two pivotable arms 5a, 5b. The two pivotable arms 5a, 5b are designed as double-arm levers in the example shown. The linear movement of the pre-tensioning element 20 and thus the linear movement of the guide element 22 are in this way converted into opposite pivoting movements of the two pivotable arms 5a, 5b, such that they move in opposite directions in a pincer-like manner and exert a clamping force on the two filament holders 2a, 2b in the installation position of the clamping device 1. These two filament holders abut against two opposite sides of the container 7 in the installation position, as Figure 2 shown. The distance between the guide element 22 of the rod-shaped pre-tensioning element 20 and the free end of the pre-tensioning element 20 (on which the abutment surface 20a is formed) matches the length of the pivotable arms 5a, 5b, such that the filament holders 2a, 2b in the installation position can laterally abut against the container 7 and the clamping force exerted on the filament holders 2a, 2b is not too large.

[0048] As can be seen from Figure 3c , each of the filament holders 2a, 2b has a concave (spherical) curved abutment surface 24a, 24b, which is formed on a protrusion of the filament holders 2a, 2b protruding in the direction of the container 7. In the installation position, the protrusions of the respective filament holders 2a, 2b engage in an annular groove (not shown) on the outer surface of the container 7. In the installation position, the spherical curved abutment surfaces 24a, 24b are placed on the equally spherical curved bottom of the annular circumferential groove, which is formed on the disc-shaped circular substrate of the container 7. The engagement of the protrusions of the filament holders 2a, 2b in the grooves on the container 7 forms a lateral guide and prevents the respective filament holders 2a, 2b from performing an undesired movement in the direction of the central axis M of the container 7 in the installation position.

[0049] To simplify the illustration, the container 7 is only designed as cylindrical, but may basically have any geometric shape. In particular, the container 7 does not have to have a continuous circumferential outer surface with only two openings for the respective electron beams 13 to pass through. In the simplest case, the container 7 is formed by two end plates, which are connected to each other via gaskets. In this case, or generally, the ionization space 12 may form its own (optionally heatable) container, which is arranged within the container 7, and the filament holders 2a, 2b are fastened to the container 7 in a clamping manner. In this case, the respective filament holders 2a, 2b abut against their adjacent surfaces 24a, 24b, for example in grooves on the circumference of one or possibly two end plates, and are clamped by the above-mentioned pliers mechanism in the mounting position of the clamping device 1.

[0050] In Figure 1 and Figures 3a - 3c the case of the clamping device 1 shown, the two filament holders 2a, 2b are clamped on opposite sides of the container 7, and the clamping is carried out symmetrically with respect to the symmetry axis S of the clamping device 1, which extends perpendicular to and intersects the central axis M of the container 7. In this way, shear forces can be avoided, which would otherwise displace the central axis M of the container 7 when the clamping force is applied. Since it is not necessary to remove the ionization device 8 for filament replacement, nor the container 7, the optimal positioning or alignment of the container 7 is still maintained when the filament is replaced.

[0051] Figure 1 and Figures 3a - 3c the clamping device 1 shown in and is generally only removed from the mass spectrometer 9 when both filaments 3a, 3b are defective and have to be replaced. A single functional filament 3a, 3b is sufficient to operate the ionization device 8; that is, when the ionization device 8 is operating, usually only one filament 3a, 3b is heated by a resistance heater (not shown) known per se to generate the electron beam 13.

[0052] Although Figure 1 and Figures 3a - 3c the clamping device 1 shown in is designed to clamp two filaments 3a, 3b on a common substrate 4, Figures 4a - 4c shows three clamping devices 1, each designed to clamp only one filament 3a on the filament holder 2a. If two filaments 3a, 3b are to be detachably fastened to the container 7, the mass spectrometer 9 may have two clamping devices 1 designed as in Figures 4a - 4c . The substrates 4 of the two clamping devices 1 may be attached to two separate openings or access ports in the vacuum housing 18, which are approximately opposite each other to avoid the occurrence of shear forces (see above).

[0053] Figure 4aThe clamping device 1 shown has a connecting element for connecting the base body 4 to the filament receptacle 2a, which connecting element is designed as an elastic element, more precisely as a leaf spring 5a. In the installed position of the clamping device 1, the leaf spring 5a presses the filament receptacle 2a against the container 7 in order to clamp the filament receptacle 2a to the container 7.

[0054] As with Figure 1 the clamping device 1 shown, Figure 4b the clamping device 1 shown has a connecting element in the form of a pivotable arm 5a, which is connected to the base body 4 via a swivel joint. The pivotable arm 5a forms a double-armed lever, on one lever arm of which the filament receptacle 2a is rigidly fastened, and a pretensioning element 20' in the form of a tension spring engages on the other lever arm, which pretensioning element 20 generates a clamping force for pressing the filament receptacle 2a against the container 7.

[0055] In Figure 4c the clamping device 1 shown, the base body 4 has a linear guide 25, more precisely a slide-through, for the rigidly designed connecting element 5a, which connecting element 5a is displaced relative to the base body 4 against the force of the pretensioning element 20' in the form of an elastic element in order to exert a clamping force on the filament receptacle 2a in the installed position of the clamping device 1 and to clamp it detachably to the container 7.

[0056] The above-described clamping device 1 makes it possible to exchange the filaments 3a, 3b without having to remove the ionization device 8 or the container 7 from the vacuum housing 18 of the mass spectrometer 1 for this purpose. On the one hand, this significantly accelerates the exchange of the filaments 3a, 3b, and on the other hand, it avoids the need to reposition or align the container 7 or the ionization device 8 when the container 7 or the ionization device 8 is reinserted into the vacuum housing 18 after the filaments 3a, 3b have been exchanged. It goes without saying that Figures 4a - 4c the clamping device 1 shown in

Claims

1. A clamping device (1) for at least one filament (3a, 3b), which comprises: at least one filament receptacle (2a, 2b) for receiving at least one filament (3a, 3b), characterized in that the clamping device (1) is designed for a detachable clamping attachment of the at least one filament receptacle (2a, 2b) to a container (7) of an ionization device (8), wherein the clamping device is designed to exert a clamping force on the at least one filament receptacle in the installed position, so as to press the at least one filament receptacle against an outer surface of the container, in the installed position, the at least one filament being able to feed an electron beam into an ionization space formed in the container.

2. The clamping device according to claim 1, further comprising: a base body (4), which is connected to the at least one filament receptacle (2a, 2b) via at least one connecting element (5a, 5b).

3. The clamping device according to claim 2, wherein the connecting element is designed as an elastic element.

4. The clamping device according to claim 2, wherein the connecting elements (5a, 5b) are designed to be rigid, and a pretensioning element (20, 20') engages into the connecting elements (5a, 5b) so as to exert a clamping force on the filament receptacle (2a, 2b).

5. The clamping device according to claim 4, wherein the base body (4) has a linear guide (25) for guiding the connecting element (5a).

6. The clamping device according to claim 4, wherein the connecting elements form pivotable arms (5a, 5b), which are connected to the base body (4) via rotary joints (6a, 6b).

7. The clamping device according to any one of claims 4 to 6, wherein the pretensioning element is designed as a spring element (20').

8. The clamping device according to claim 6, which has two connecting elements in the form of pivotable arms (5a, 5b), each connecting element being connected to the base body (4) via a rotary joint (6a, 6b).

9. The clamping device according to claim 8, wherein the pretensioning element (20) is designed to pivot two pivotable arms (5a, 5b) in opposite directions around each rotary joint (6a, 6b) so as to clamp and fasten two filament receptacles (2a, 2b) attached to the pivotable arms (5a, 5b) on two opposite sides of the container (7).

10. The clamping device according to any one of claims 4 to 6, 8 to 9, wherein the pretensioning element (20) is designed to be rigid, is guided in a guide rail of the base body (4), and wherein the pretensioning element (20) has a free end, which has an abutment surface (20a) for abutting against the container (7).

11. The clamping device according to claim 10, wherein the pretensioning element (20) has a guiding element (22), which engages on two pivotable arms (5a, 5b).

12. The clamping device according to claim 3, wherein the elastic element is a leaf spring (5a).

13. The clamping device according to claim 7, having two connecting elements in the form of pivotable arms (5a, 5b), each connecting element being connected to the base body (4) via a swivel joint (6a, 6b).

14. The clamping device according to claim 10, wherein the pretensioning element (20) is rod-shaped.

15. The clamping device according to claim 10, wherein the pretensioning element (20) is guided in a linear guide (21) of the base body (4).

16. The clamping device according to claim 7, wherein the spring element is connected at one end to the base body (4) and at the other end to the connecting element (5a).

17. A mass spectrometer (9), which comprises: an ionization device (8) having a container (7) in which an ionization space (12) for ionizing a gas (11) is formed, at least one clamping device (1) according to any one of the preceding claims, which is designed for a detachable clamping attachment of at least one filament receptacle (2a, 2b) to the container (7), and a vacuum housing (18) to which the clamping device (1) is detachably connected.

18. The mass spectrometer according to claim 17, wherein the rigidly designed pretensioning element (20) of the clamping device (1) abuts on the container (7) with its abutment surface (20a).

19. The mass spectrometer according to claim 17, wherein, the base body (4) of the clamping device (1) is detachably connected to the vacuum housing (18).

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