HOLDING DEVICE FOR AT LEAST ONE FILAMENT AND MASS SPECTROMETER

Abstract

The invention relates to a holding device for at least one filament, comprising: at least one filament receptacle for receiving the at least one filament. The holding device is designed for the detachable attachment, in particular clamping attachment, of the at least one filament receptacle to a container of an ionization device. The invention also relates to a mass spectrometer comprising: an ionization device having a container in which an ionization space for ionizing a gas is formed, at least one holding device which is designed for the detachable attachment, in particular clamping attachment, of the at least one filament receptacle to the container, and a vacuum housing to which the holding device, in particular a base body of the holding device, is detachably connected.

Claims

1. A holding device for at least one filament, comprising: at least one filament receptacle for receiving the at least one filament, characterized in that the holding device is designed for the detachable attachment, in particular clamping attachment, of the at least one filament receptacle to a container of an ionization device.

2. The holding device according to claim 1, further comprising: a base body which is connected to the at least one filament receptacle via at least one connecting element.

3. The holding device according to claim 2, wherein the connecting element is designed as a resilient element, in particular as a leaf spring.

4. The holding device according to claim 2, wherein the connecting element is designed so as to be rigid and a pretensioning element engages into the connecting element in order to apply a clamping force to the filament receptacle.

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

6. The holding device according to claim 4, wherein the connecting element forms a pivotable arm which is connected to the base body via a rotary joint.

7. The holding device according to claim 4, wherein the pretensioning 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.

8. The holding device according to claim 6, which has two connecting elements in the form of pivotable arms which are each connected to the base body via a rotary joint.

9. The holding device according to claim 8, wherein the pretensioning element is designed to pivot the two pivotable arms in opposite directions about each rotary joint, in order to fasten the two filament receptacles attached to the pivotable arms on two opposite sides of the container in a clamping manner.

10. The holding device according to claim 4, wherein the pretensioning element is designed so as to be rigid, in particular rod-shaped, is guided in a guide track, in particular in a linear guide, of the base body, and in which the pretensioning element has a free end with an abutment surface for abutment with the container.

11. The holding device according to claim 10, wherein the pretensioning element has a guide element which engages on the two pivotable arms.

12. A mass spectrometer comprising: an ionization device having a container in which an ionization space for ionizing a gas is formed, at least one holding device according to claim 1 which is designed for the detachable attachment, in particular clamping attachment, of the at least one filament receptacle to the container, and a vacuum housing to which the holding device, in particular a base body of the holding device, is detachably connected.

13. The mass spectrometer according to claim 12, wherein the rigidly designed pretensioning element of the holding device abuts with its abutment surface on the container.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments are shown in the schematic drawing and are explained in the following description. In the drawing:

[0028] FIG. 1 is a schematic representation of a holding device which has two filament receptacles,

[0029] FIG. 2 is a schematic representation of a mass spectrometer which has the holding device of FIG. 1 for the clamping attachment or fastening of two filament receptacles on a container of an ionization device,

[0030] FIG. 3a-c are schematic representations of the holding device of FIG. 1 and of the container to which the two filament receptacles are fastened in a clamping manner, and

[0031] FIG. 4a-c are schematic representations of holding devices which are designed for the clamping attachment of a filament receptacle to the container.

DETAILED DESCRIPTION

[0032] In the following description of the drawings, identical reference signs are used for identical or functionally identical components.

[0033] FIG. 1 schematically shows a holding device 1 which comprises two filament receptacles 2a,b for receiving (and for holding) a respective filament 3a,b (cf. FIG. 2), which is not depicted in FIG. 1. The first and second filament receptacles 2a,b are connected to a base body 4 of the holding device 1 via a first and second connecting element 5a,b in each case. In the example shown in FIG. 1, the two connecting elements are each designed in the form of a rigid, pivotable arm 5a,b. The pivotable arms 5a, b are each connected to the base body 4 via their own rotary joint 6a,b.

[0034] FIG. 2 shows the two filament receptacles 2a,b in an installation position of the holding device 1 in a mass spectrometer 9. As can be seen in FIG. 2, in the installation position of the holding device 1, the two filament receptacles 2a,b rest on two opposite sides of a container 7 of an ionization device 8 which forms part of the mass spectrometer 9. When installing the holding device 1, the two filament receptacles 2a,b are attached or fastened to the container 7 in a clamping manner due to a pliers movement of the two pivotable arms 5a,b.

[0035] In the example shown, the container 7 has a substantially cylindrical outer surface with which the filament receptacles 2a,b are brought into abutment, the pivotable arms 5a,b exerting a clamping force on the filament receptacles 2a,b, as described in more detail below in connection with FIG. 3a-c.

[0036] The ionization device 8 of the mass spectrometer 9 shown in FIG. 2 has an inlet or an inlet system 10 for feeding a gas 11 to be analyzed into an ionization space 12 which is formed in the container 7 of the ionization device 8. As can also be seen in FIG. 2, the first filament 3a generates an electron beam 13 which is fed to the ionization space 12 via a side opening in the container 7 and serves to generate an ionized gas 14 to be analyzed by electron impact ionization.

[0037] The mass spectrometer 9 also has an extraction device 15 in the form of an electrode arrangement, in order to extract the ionized gas 12 from the ionization space 10 and to accelerate it in the direction of a transfer quadrupole 16 and, if necessary, to focus it, before this is analyzed by mass spectrometry in a detector 17, for example in the form of a time-of-flight detector. In addition to transporting the ionized gas 14, the transfer quadrupole 16 can also serve for mass separation or for mass selection. It goes without saying that the mass spectrometer 9 shown in FIG. 2 is to 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.

[0038] The mass spectrometer 9 shown in FIG. 2 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 to the extraction device 15 or to the transfer quadrupole 16. The components or stages within the vacuum housing 18 are pumped differentially by means of a vacuum pump (not shown). The interior of the vacuum housing 18 of the mass spectrometer 9 is not readily accessible to an operator from the outside.

[0039] In order to nevertheless allow the filaments 3a,b to be exchanged quickly, the base body 4 of the holding device 1 is fastened, typically screwed, in its installation position in the mass spectrometer 1 to the vacuum housing 18 of the mass spectrometer 9 via a detachable connection. In the example shown, a plate-shaped portion 4a of the base body 4 is positioned on the outside of the vacuum housing 18 and flanged to it or screwed to it. A portion 4b of the base body 4 protruding beyond the plate-shaped portion 4a extends into the vacuum housing 18 of the mass spectrometer 9 in the installation position of the holding device 1.

[0040] For the exchange of the two filaments 3a,b in the mass spectrometer 9 shown in FIG. 2, it is therefore not necessary to remove the ionization device 8, in particular the container 7, from the vacuum housing 18 of the mass spectrometer 9; rather, it is sufficient if the externally accessible portion 4a of the base body 4 is detached from the vacuum housing 18 and the holding device 1 is removed from the vacuum housing 18, the clamping of the two filament receptacles 2a, b being released.

[0041] For the exchange of the filaments 2a,b, it is necessary to break the vacuum in the vacuum housing 18. In order to avoid that moisture is deposited on the components located in the vacuum housing 18 or on the inside of the vacuum housing 18, the interior of the vacuum housing 18 is vented with an inert gas, for example with (dry) nitrogen or purged with an inert gas. In this way, the pumping time during the subsequent renewed evacuation of the vacuum housing 18 can be significantly reduced.

[0042] In order to reposition the holding device 1 in the vacuum housing 18 after the exchange of the filaments 2a,b, the protruding portion 4a of the base body 4 is introduced, together with the filament receptacles 2a which are connected to the base body 4 via the two pivotable arms 5a,b, into the vacuum housing 18 along the Z direction of an XYZ coordinate system shown in FIG. 2, specifically via an access or via an opening in the vacuum housing 18, which is located in the Z direction above a main axis or central axis M of the ionization device 8. In the mass spectrometer 9 shown in FIG. 2, the plate-shaped portion 4a of the base body 4 therefore runs parallel to the XY plane, which corresponds to the plane of the drawing.

[0043] In order to press the two filament receptacles 2a,b against the outer surface or the circumference of the container 7, so that they are fixed or clamped in a predetermined position relative to the container 7, the holding device 1 shown in FIG. 1 and in FIG. 3a-c has a rigidly designed, rod-shaped pretensioning element 20. The rod-shaped pretensioning element 20 extends along an axis of symmetry S of the holding device 1 which runs perpendicular to the plate-shaped portion 4a of the base body 4 and which corresponds to the Z direction in the installation position of the holding device 1 in the vacuum housing 18.

[0044] The rod-shaped pretensioning element 20 has an abutment surface 20a (cf. FIG. 1) which is pressed against the container 7, more precisely against its outer surface, when inserting the holding device 1 into the vacuum housing 18. The rod-shaped pretensioning element 20 is displaced in a linear guide 21 (a rail) formed in the protruding portion 4b of the base body 4 along the axis of symmetry S, which corresponds to the Z direction in the installation position of the holding device 1. During the linear displacement of the pretensioning element 20 in the Z direction, a guide element 22 (in the example shown, a bolt) attached to the pretensioning element 20, which protrudes laterally over an elongated hole in the protruding portion 4a of the base body 4, is displaced in the direction of the plate-shaped portion 4a of the base body 4.

[0045] The guide element 22 in the form of the protruding bolt engages the two pivotable arms 5a,b, more precisely, the guide element 22 in the form of the bolt engages in two elongated holes 23a,b of a respective first lever arm of the two pivotable arms 5a,b, which are designed as double-armed levers in the example shown. The linear movement of the pretensioning element 20 and thus of the guide element 22 is converted in this way into an opposing pivoting movement of the two pivotable arms 5a,b, so that they are moved in opposite directions in the manner of pliers and exert a clamping force in the installation position of the holding device 1 on the two filament receptacles 2a,b, which, in the installation position, abut on the two opposite sides of the container 7, as shown in FIG. 2. The distance between the guide element 22 of the rod-shaped pretensioning element 20 and the free end of the pretensioning element 20 on which the abutment surface 20a is formed is matched to the length of the pivotable arms 5a,b, such that the filament receptacles 2a,b in the installation position can be brought laterally into abutment with the container 7 and a—not too great—clamping force is exerted on the filament receptacles 2a,b.

[0046] As can be seen in FIG. 3c, the filament receptacles 2a,b each have a concave (spherically) curved abutment surface 24a, 24b, which is formed on a projection of the filament receptacles 2a,b protruding in the direction of the container 7. In the installation position, the projection of the respective filament receptacle 2a,b engages in an annular groove (not shown) on the outer surface of the container 7. In the installation position, the spherically curved abutment surface 24a, 24b rests on the likewise spherically curved bottom of the annular circumferential groove which is formed on a disc-shaped, circular base plate of the container 7. The engagement of the projection of the filament receptacle 2a,b in the groove on the container 7 forms a lateral guide and prevents the respective filament receptacle 2a,b from executing an undesired movement in the direction of the central axis M of the container 7 in the installation position.

[0047] The container 7 is only designed to be cylindrical to simplify the representation, but can basically have any geometry. In particular, it is not necessary for the container 7 to have a continuous, circumferential outer surface which has only two openings for the passage of a respective electron beam 13. In the simplest case, the container 7 is formed from two end plates which are connected to one another via spacers. In this case, or in general, the ionization space 12 can form its own (optionally heatable) container which is arranged within the container 7 to which the filament receptacles 2a,b are fastened in a clamping manner. In this case, the respective filament receptacle 2a,b is brought into abutment with its abutment surface 24a, 24b, for example in a groove on the circumference of one or possibly both end plates and clamped by the pliers mechanism described above in the installation position of the holding device 1.

[0048] In the case of the holding device 1 shown in FIG. 1 and in FIG. 3a-c, the two filament receptacles 2a,b are clamped on opposite sides of the container 7, the clamping being carried out symmetrically to the axis of symmetry S of the holding device 1, which extends perpendicular to the central axis M of the container 7 and intersects the central axis M of the container 7. In this way, shear forces can be avoided which could otherwise displace the central axis M of the container 7 when applying the clamping force. Since the ionization device 8 and thus the container 7 do not have to be removed for the filament replacement, the optimized positioning or alignment of the container 7 is retained when the filament is changed.

[0049] The holding device 1 shown in FIG. 1 and FIG. 3a-c is typically only removed from the mass spectrometer 9 when both filaments 3a,b are defective and have to be replaced. A single functional filament 3a, 3b is sufficient for the operation of the ionization device 8; i.e., when the ionization device 8 is in operation, typically only one filament 3a,b is heated by means of a resistance heater known per se (not shown), in order to generate an electron beam 13.

[0050] While the holding device 1 shown in FIG. 1 and in FIG. 3a-c is designed to hold two filaments 3a,b on a common base body 4, FIG. 4a-c show three holding devices 1, each designed for holding only one single filament 3a on a filament receptacle 2a. In the event that two filaments 3a,b are to be detachably fastened to the container 7, the mass spectrometer 9 can have two holding devices 1 which are designed as in FIG. 4a-c. The base bodies 4 of the two holding devices 1 can be attached to two separate openings or accesses in the vacuum housing 18, which are generally opposite one another in order to avoid the occurrence of shear forces (see above).

[0051] The holding device 1 shown in FIG. 4a has a connecting element for connecting the base body 4 to the filament receptacle 2a, which is designed as a resilient element, more precisely as a leaf spring 5a. In the installation position of the holding device 1, the leaf spring 5a presses the filament receptacle 2a against the container 7 in order to clamp the filament receptacle 2a onto the container 7.

[0052] The holding device 1 shown in FIG. 4b, like the holding device 1 shown in FIG. 1, has a connecting element in the form of a pivotable arm 5a, which is connected to the base body 4 via a rotary joint. The pivotable arm 5a forms a double-armed lever, on one lever arm of which the filament receptacle 2a is rigidly fastened and on the other lever arm a pretensioning element 20′ in the form of a tension spring engages, which generates a clamping force for pressing the filament receptacle 2a against the container 7.

[0053] In the holding device 1 shown in FIG. 4c, the base body 4 has a linear guide 25, more precisely a sliding feed-through, for the rigidly designed connecting element 5a, which is displaced relative to the base body 4 against the force of a pretensioning element 20′ in the form of a resilient element, in order to exert a clamping force on the filament receptacle 2a in the installation position of the holding device 1 and to clamp it detachably to the container 7.

[0054] The holding devices 1 described above make it possible to exchange the filaments 3a,b 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 accelerates the exchange of the filaments 3a,b significantly and, on the other hand, avoids the need to reposition or align the container 7 or the ionization device 8 when reinserting them into the vacuum housing 18 after the filaments 3a,b have been exchanged. It goes without saying that the holding devices 1 shown in FIG. 4a-c can also be used in mass spectrometers 9 or in ionization devices 8 which have only one filament 3a.

[0055] Although elements have been shown or described as separate embodiments above, portions of each embodiment may be combined with all or part of other embodiments described above.

[0056] Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are described as example forms of implementing the claims.