GB2609082A

GB2609082A - Mounting Assembly for Ion Source Enclosure

Info

Publication number: GB2609082A
Application number: GB2207560.0A
Authority: GB
Inventors: Malpas Oliver
Original assignee: Micromass UK Ltd
Current assignee: Micromass UK Ltd
Priority date: 2021-06-03
Filing date: 2022-05-24
Publication date: 2023-01-25
Anticipated expiration: 2042-05-24
Also published as: GB202207560D0; GB2609082A9; GB202107940D0; GB2609082B

Abstract

A mass and/or ion mobility spectrometer comprising a mounting assembly 6 for mounting an ion source enclosure (2, Fig. 2) to a vacuum housing. The mounting assembly and vacuum housing are configured with cooperating elements, e.g. at least one hook 30 on the vacuum housing which is arranged to receive portion(s) of the mounting plate, that interlock when the mounting assembly and vacuum housing are in a first position relative to each other so as to prevent the mounting assembly being moved in a first direction away from the vacuum housing. The cooperating elements are configured such that when at least part of the mounting assembly is slid relative to the vacuum housing in a second, orthogonal direction (24) to a second, different position, the mounting assembly is able to be moved in the first direction away from the vacuum housing. The mounting assembly may comprise a second member 34 which can slide relative to a first member 32 whilst coupled thereto.

Description

MOUNTING ASSEMBLY FOR ION SOURCE ENCLOSURE 5 FIELD OF THE INVENTION The present invention relates generally to mass spectrometers and/or ion mobility spectrometers. In particular, the present invention relates to mounting one component of the spectrometer to another component.

BACKGROUND

Mass and/or ion mobility spectrometers comprise an ion source enclosure, in which ions from an analytical sample are generated, and a mass and/or mobility analyser for analysing the ions (or ions derived therefrom). The spectrometer may also include various other ion-optical components. Typically, it is desired to operate the analyser(s) and the other ion-optical components at a pressure below atmospheric pressure and hence these components are provided in a vacuum housing. The vacuum housing may comprise one or more vacuum chambers that are pumped by one or more vacuum pumps. The ion source enclosure is therefore typically mounted to a vacuum housing at the upstream end of the spectrometer.

From time to time, it may be necessary to demount and remount the ion source enclosure from the rest of the spectrometer. For example, if the ion source is a Matrix Assisted Laser Desorption Ionisation (MALDI) ion source, or another type of ion source having a target plate or sample plate, then it may be required to remove the ion source enclosure from the vacuum housing in order to change the target or sample plate or replenish it with more sample. Alternatively, it may be desired to change the ion source for a different type of ion source. For example, a first type of ion source (e.g. an Electrospray 'ES!' ion source) may be used when setting up (e.g. calibrating) the spectrometer, but then a second, different type of ion source (e.g. a MALDI ion source) may be required or desired for ionising an analytical sample. Alternatively, it may be necessary to remove the ion source in order to replace, clean or otherwise maintain one or more parts of the ion source or one or more part in the first vacuum chamber. For example, it may be necessary to clean the aperture between the ion source enclosure and first vacuum chamber if it becomes contaminated or blocked. It may also be necessary to clean the ion guide arranged in the first vacuum chamber, since this may become contaminated.

However, the process of demounting and remounting the ion source enclosure in known spectrometers is relatively complex and time consuming. Also, the conventional mechanisms involved in demounfing and remounting the ion source enclosure place -2 -undesirable limitations on the geometry of the insurument, since these mechanisms must remain accessible.

SUMMARY

The present invention provides a mass and/or ion mobility spectrometer comprising: an ion source enclosure; a vacuum housing; and a mounting assembly for mounting the ion source enclosure to the vacuum housing; wherein the mounting assembly and vacuum housing are configured with cooperating elements that interlock when the mounting assembly and vacuum housing are in a first position relative to each other so as to prevent the mounting assembly being moved in a first direction away from the vacuum housing, and wherein the cooperating elements are configured such that when at least part of the mounting assembly is slid relative to the vacuum housing in a second, orthogonal direction and to a second, different position, the mounting assembly is able to be moved in the first direction away from the vacuum housing.

The present invention provides a locking mechanism for holding the mounting assembly and vacuum housing together that is relatively easy to unlock, i.e. by sliding said at least part of the mounting assembly in the second direction. This may enable the locking mechanism to be unlocked whilst only requiring little access to the mounting assembly, e.g. access to one side of the mounting assembly such that it can be pulled or pushed so as to unlock it from the vacuum housing. This configuration places fewer restrictions on the geometry of the remaining parts of the spectrometer, since access to the mounting assembly is no longer required from those other parts.

The cooperating elements may be configured such that said at least part of the mounting assembly is able to be moved relative to the vacuum housing in an opposite direction to the second direction and back to the first position so that said cooperating elements interlock and the mounting assembly is not able to be moved in the first direction away from the vacuum housing.

The ion source enclosure may be fixedly attached to a first side of the mounting assembly (i.e. the upstream side) and the second, opposite side of the mounting assembly is to be mounted against the vacuum housing. By this it is meant that the attachment between the ion source enclosure and the mounting assembly may not be intended to be undone. This attachment would therefore require tools and may require an engineer to undo. In contrast, the downstream side of the mounting assembly is intended to be repeatedly mounted to, and demounted from, the vacuum housing, e.g. by the operator that is using the spectrometer to analyse a sample.

Therefore, the cooperating elements of the mounting assembly and vacuum housing may be configured such that the mounting assembly can be interlocked with, and unlocked from, the vacuum housing by hand and without the use of any tools. -3 -

The ion source enclosure may house any ionisation device for ionising an analytical sample. The ion source enclosure may house a target plate or sample slide on which an analytical sample is to be deposited and subsequently ionised. For example, the ion source enclosure may house a MALDI or DESI target plate.

The mounting assembly may include an orifice for allowing ions to pass from the ion source enclosure into the vacuum housing when the ion source enclosure is mounted to the vacuum housing by the mounting assembly.

Said first direction may be the upstream direction, i.e. the direction from the vacuum housing towards the ion source enclosure. This direction may be parallel with the axis through the orifice in the mounting assembly.

The second direction is orthogonal to the first direction.

The vacuum housing includes one or more vacuum chambers. The mounting assembly may be mounted to an upstream end of the most upstream vacuum chambers. For example, the mounting assembly may be mounted to an isolation valve assembly that is part of the first vacuum chamber.

The vacuum housing may comprise an orifice in an upstream end thereof, for receiving ions from the ion source enclosure, and a seal surrounding this orifice; wherein said cooperating elements are configured such that when said at least part of the mounting assembly is slid relative to the vacuum housing in a direction opposite to the second direction and back to the first position, the mounting assembly is forced against said seal so as to compress it.

The seal may be an 0-ring or any other shape or type of seal.

The cooperating elements may comprise at least one hook arranged on the vacuum housing that has at least one respective recess in it, and when said at least one recess is configured to receive the mounting assembly when said at least part of the mounting assembly is slid in a direction opposite to said second direction and into said first position. Similarly, the mounting assembly may be removed from the at least one recess by sliding said at least part of the mounting assembly in the second direction to said second position.

The recess(es) of the hook(s) may be slot(s).

The vacuum housing may comprise an orifice in an upstream end for receiving ions from the ion source enclosure and a seal surrounding the orifice; wherein the at least one hook and mounting member may be configured such that, when the mounting assembly is slid in a direction opposite to said second direction and into the at least one recess in the at least one respective hook, the mounting member is urged in a direction opposite to said first direction such that it compresses the seal.

For example, the upstream surface of the recess in each hook may be at a nonzero acute angle to the second direction so that, as the mounting member is pushed in the direction opposite to the second direction and into the recess, the mounting member rides along the upstream surface of the hook recess and is forced in the direction opposite to said first direction and towards the seal. Alternatively, or additionally, the upstream surface of the portion of the mounting member that enters the hook recess may be at a non-zero -4 -acute angle to the second direction so that, as the mounting member is pushed in the direction opposite to the second direction and into the recess, the mounting member rides along the upstream side of the hook recess and is forced in the direction opposite to said first direction and towards the seal.

The spectrometer may comprise at least two or at least three of said hooks, wherein the hooks are spaced apart circumferentially around the outside of the seal. This arrangement of hooks assists in maintaining the mounting member firmly against all parts of the seal such that it may be gas-tight.

The hooks may be spaced equidistantly around the circumference of the seal.

The spectrometer may comprise a plurality of said hooks, wherein the recesses of the hooks are arranged on the same side of the hooks and configured so that the mounting assembly can slide in the second direction and out of the hooks simultaneously, and can be slid in the opposite direction and into the recesses simultaneously.

The mounting assembly may comprise: a planar part having opposing major surfaces for mounting against the ion source enclosure and the vacuum housing; and (i) a first flange that is substantially orthogonal to the planar part and configured to hang on an upwardly directed surface of the vacuum housing when the mounting assembly is in the first position; and/or (ii) a second flange that is substantially orthogonal to the planar part and configured to abut a vertical surface of the vacuum housing when the mounting assembly is in the first position.

The first flange may be configured such that it hangs on the upwardly directed surface of the vacuum housing as the mounting assembly is slid in the direction opposite to the second direction and into the recess(es) in the hook(s). The first flange may therefore act as a guiding member to guide the desired part(s) of the mounting assembly into the recess(es) of the hook(s).

The second flange may provide a handle to pull the mounting assembly in the second direction.

The fastening member may be provided on the second flange.

The spectrometer may comprise a fastening member for releasably fastening the mounting assembly to the vacuum housing such that it is unable to be slid in the second direction.

The fastening member may be a screw that screws the mounting assembly to the vacuum housing.

The screw may be a thumb screw such as for screwing the mounting assembly to the vacuum housing without the use of any tools.

The screw may be an elongated screw and the vacuum housing may have a cooperating elongated recess for receiving the screw. The axes of the screw and recess may be in the second direction (when the mounting assembly and vacuum housing are interlocked).

The mounting assembly may comprise: a first member having a planar part comprising opposing major surfaces for mounting against the ion source enclosure and the vacuum housing; and a second member that is coupled to said first member such that the -5 -second member can slide relative to the first member whilst coupled thereto; wherein the second member and vacuum housing comprise said cooperating elements.

The second member may be slidable relative to the first member in the plane of the first member (i.e. it may be slidable back and forth in said second direction and in the direction opposite to the second direction).

This configuration avoid the first member having to be slid in the second direction when unlocking the mounting assembly from the vacuum housing, or from having to be slid in the opposite direction when locking the mounting assembly to the vacuum housing. As such, the first member can provide a static interface between the ion source enclosure and vacuum housing. This is particularly beneficial if one or more seals are provided against one or more of the major surfaces of the first member, since it would then be difficult to slide first member.

The first member may have an orifice for allowing ions to pass therethrough, from the ion source enclosure to the vacuum housing. A seal may be provided around the orifice on the upstream major surface and/or the downstream major surface of the first member.

One of the first and second members may comprise at least one slot, and the other of the first and second members may comprise at least one respective protrusion that is located in said slot such that the at least one protrusion is able to slide within the slot to enable the second member to move relative to the first member.

Each of the at least one slots may be elongated in the second direction.

The slots may be arranged on the mounting assembly in the vicinity of the hooks (when the mounting assembly is mounted to the vacuum housing).

It is believed that the mounting assembly itself is new it its own right. Accordingly, the present invention also provides a mounting assembly for mounting an ion source enclosure to a vacuum housing of a mass and/or ion mobility spectrometer, the mounting assembly comprising: a first member having a planar part comprising opposing major surfaces for mounting between and against the ion source enclosure and the vacuum housing; and a second member that is coupled to said first member such that the second member can slide relative to the first member whilst coupled thereto.

The mounting assembly may have any of the features of the mounting assembly described above.

The present invention also provides a method of mounting an ion source enclosure to a vacuum housing of a mass and/or ion mobility spectrometer using the mounting assembly described herein.

It is also contemplated that the mounting assembly may be used to mount together two components of the spectrometer other than the ion source enclosure and vacuum housing. For example, the mounting assembly may be used to mount a vacuum pump to the vacuum housing.

Accordingly, the present invention also provides a mounting assembly for mounting first and second components of a mass and/or ion mobility spectrometer together, the mounting assembly comprising: a first member having a planar part comprising opposing -6 -major surfaces for mounting between and against the first and second components; and a second member that is coupled to said first member such that the second member can slide relative to the first member whilst coupled thereto.

The present invention also provides a method of mounting a first component of a mass and/or ion mobility spectrometer to a second component of the mass and/or ion mobility spectrometer using the mounting assembly described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which: Fig. 1 shows a schematic of a spectrometer according to an embodiment of the present invention; Fig. 2 shows the portion of the spectrometer in Fig. 1 that includes the ion source enclosure, mounting assembly and isolation valve assembly; Fig. 3 shows the portion of the spectrometer shown in Fig. 2, when the mounting assembly has been demounted and moved away from the isolation valve assembly; and Figs. 4A and 4B show detailed views of the engagement between the mounting assembly and the isolation valve assembly.

DETAILED DESCRIPTION

Fig. 1 shows a schematic of an embodiment of the present invention. The spectrometer comprises an ion source enclosure 2 that is removably mounted to a vacuum housing 4 by a mounting assembly 6. The details of the mounting assembly 6 will be discussed further below. The vacuum housing 4 comprises a first vacuum chamber 8 at an upstream end thereof (the end nearest the source enclosure 2) and a second vacuum chamber 10 downstream of the first vacuum chamber. An isolation valve assembly 12 may be provided at the upstream end of the vacuum housing 4, in the first vacuum chamber 8.

The mounting assembly 6 comprises a first (inlet) orifice 14 for allowing ions to pass from the ion source enclosure 2 to the isolation valve assembly 12. Similarly, the isolation valve assembly 12 comprises a selectively openable and closable orifice which, when open, allows these ions to continue and pass into the first vacuum chamber 8. A further orifice 16 is arranged in the wall between the first and second vacuum chambers 8,10 such that the ions can pass from the first vacuum chamber 8 into the second vacuum chamber 10.

A roughing pump or backing pump 18 may be connected to the first vacuum chamber 8 for evacuating the first vacuum chamber 8. This pump 18 reduces the pressure in the first vacuum chamber 8 to a pressure below atmospheric pressure. A second pump 20, such as a turbomolecular pump, may be connected to the second vacuum chamber 10 for evacuating the second vacuum chamber 10 to a pressure below that of the first vacuum chamber 8. It is typically desired to reduce the pressure in the second vacuum chamber 10 -7 -to a low pressure in order for a mass analyser housed therein to operate optimally. The inlet of the first pump 18 may be connected to the outlet 22 of the second pump 20 so that the first pump 18 can pump the outlet 22 of the second pump down, e.g. to a pressure of a few milli-bars. This process is known in the art as the first pump 18 backing the second pump 20.

In use, the ion source in the ion source enclosure 2 ionises an analytical sample so as to produce ions. The ions then pass from the ion source enclosure 2, through the first orifice 14 in the mounting assembly, through the isolation valve 12 (which is maintained open) in the isolation valve assembly and into the first vacuum chamber 8. The ions are then guided through the first vacuum chamber 8 by an ion guide (not shown) and into the lower pressure second vacuum chamber 10, wherein they may be guided into a mass analyser (not shown) housed therein.

From time to time, it may be desired to remove the ion source enclosure 2 from the rest of the spectrometer for various reasons. However, if the ion source enclosure 2 is removed then the spectrometer is no longer sealed. If no preventative action is taken then this could cause a relatively high gas flow rate into the first vacuum chamber 8. This could cause the pressure in the first vacuum chamber 8 to rise and hence increase the gas flow rate through the orifice 16 into the second vacuum chamber 6. As such, the pumps 18,20 may be unable to maintain the desired pressures in the first and second vacuum chambers 8,10. The increased pressure may result in electrical arcing or voltage break-down, e.g. in the second vacuum chamber 10, due to the high voltages that may be applied to ion-optical components therein. Also, once the ion source enclosure 2 has been remounted then significant time must be spent pumping the vacuum chambers 8,10 back down to their desired pressures. In order to mitigate problems such as these, the isolation valve assembly 12 may be provided. The isolation valve assembly 12 is selectively operable so as to close an orifice therein and prevent gas flow into the upstream end of the first vacuum chamber 8. The isolation valve 12 may be closed prior to removing the ion source enclosure 2 from the spectrometer. As such, when the ion source enclosure 2 is removed there will be relatively little or no gas flow into the upstream end of the first vacuum chamber 8 and so the first and second pumps 18,20 are able to maintain the first and second vacuum chambers 8,10 at their desired pressures. When the ion source enclosure 2 is remounted to the isolation valve assembly 12 at the upstream end of the vacuum housing 4, the isolation valve 12 is then opened such that ions are able to pass from the ion source enclosure 2 to the first vacuum chamber 8 and the spectrometer is able to be used to analyse ions again.

Fig. 2 shows a portion of a spectrometer according to an embodiment of the present invention. More specifically, this shows the portion of the spectrometer that includes the ion source enclosure 2, the mounting assembly 6 and the isolation valve assembly 12. The first vacuum chamber 8 and other downstream components are not shown.

In the illustrated embodiment, the ion source enclosure 2 houses a MALDI target plate. The spectrometer therefore comprises a laser that is directed onto the sample plate -8 -so as to generate ions within the ion source enclosure. However, it will be appreciated that the ion source enclosure may house any type of ionisation device for generating ions.

As can be seen from Fig. 2, the ion source enclosure 2 is attached to an upstream side of the mounting assembly 6. The mounting assembly 6 and isolation valve assembly 12 are configured to inter-engage each other such that the mounting assembly 6 (and hence the ion source enclosure 2) can be mounted to the upstream end of the isolation valve assembly 12. More specifically, the mounting assembly 6 and the upstream end of the isolation valve assembly 12 are configured so as to be repeatedly inter-engagable and disengagable such that the ion source enclosure 2 may be repeatedly mounted and demounted from the isolation valve assembly 12 of the vacuum housing 4. In the embodiment shown, the mounting assembly 6 may be moved in the plane defined by the interface between the mounting assembly 6 and isolation valve assembly 12 in order for the mounting assembly 6 to engage and disengage the isolation valve assembly 12. Arrow 24 shows the direction in which the mounting assembly 6 is moved in order to disengage it from the isolation valve assembly 12.

Fig. 3 shows a portion of the embodiment shown in Fig. 2, when the mounting assembly 6 has been demounted and moved away from the isolation valve assembly 12. From this view it can be seen that the upstream face of the isolation valve assembly 12 comprises a seal 26 surrounding the entrance orifice 28 into the isolation valve assembly 12. This seal 26 is illustrated as being an 0-ring seal. However, the seal 26 may be any other shape or type of seal, provided that it is arranged and configured such that when the mounting assembly 6 is mounted to the isolation valve assembly 12, the mounting assembly 6 is pressed against the seal 26 so as to prevent gas passing the seal in the radial direction at the interface between the mounting member and isolation valve assembly. This maintains a gas-tight seal around the orifice 28 between the mounting assembly 6 and the isolation valve assembly 12, at the interface between the mounting assembly and isolation valve assembly.

It can also be seen that hooks 30 project in the upstream direction from the upstream end of the isolation valve assembly 12. As will be described in more detail in relation to Figs. 4A and 4B, these hooks 30 are configured to engage the mounting assembly 6, when it is mounted to the isolation valve assembly 12, so as to hold the mounting assembly 12 in place against the seal 26 in a gas tight manner. The hooks 30 are circumferentially spaced around, and radially outside of, the entry orifice 28 and seal 26 of the isolation valve assembly 12.

Figs. 4A and 4B show schematics of the mounting assembly whilst in a position in which it is mounted to the upstream end of the isolation valve assembly 12. In order to simplify the illustration, the ion source enclosure 2 that is attached to the upstream side of the mounting member 6 is not shown.

Referring to the perspective view of Fig. 4A, the mounting assembly 6 comprises a first, plate member 32 for providing a gas-tight interface between the isolation valve assembly 12 and the ion source enclosure 2. The mounting assembly 6 also comprises a second, clip member 34 that is configured to cooperate with and mechanically inter-engage -9 -with the upstream end of the isolation valve assembly 12 so as to releasably interlock the mounting assembly 6 (and hence ion source enclosure 2) with the isolation valve assembly 12.

The first, plate member 32 defines an orifice 36 therein for allowing ions to pass through it, from the ion in source enclosure 2 into the entrance orifice 28 in the isolation valve assembly 12. The first member 32 may also comprise a second orifice 38, e.g. for providing clearance so as to avoid other devices in the vicinity of the first member 32. The downstream face of the first member 32 is configured such that, when it is pressed against the upstream end of the isolation valve assembly 12, it engages the seal 26 on the upstream end of the isolation valve assembly 12 in a gas-tight manner. As described above, the ion source enclosure 2 is connected to the upstream side of the mounting assembly 6 and a conduit is provided between the ion source enclosure 2 and the orifice 36 in the first member 32 of the mounting assembly 6 for allowing ions to pass therethrough. The upstream face of the first member 32 comprises a seal 40 that extends around the orifices 36,38 so that the interface between the ion source enclosure 2 and the first member 32 is sealed gas-tight around the conduit.

The first member 32 and second members 34 of the mounting assembly 6 are coupled to each other such that they may move relative to each other. This coupling may be configured such that the members 32,34 are able to slide relative to each other in a direction orthogonal to the axis through the orifice 36 in first member 32. For example, one of the members 32 may have at least one protrusion 42 that is located within at least one respective slot 44 on the other member 34, so as to allow the at least one protrusion 42 to slide within the at least one slot 44. The coupling may be configured such that the first and second members 32,34 remain coupled together even when one member 34 is slid relative to the other member 32 in both directions. For example, each of the at least one protrusion 42 on said one member 32 may extend through the respective slot 44 on the other member 34 and may have a head that is configured such that it cannot be retracted through the slot 44, thereby retaining the first and second members coupled together. In the depicted embodiment the first member 32 comprises three such protrusions 42 that extend through three respective slots 44 in the second member. Each protrusion 42 has a head having a diameter that is larger than the width of its respective slot 44 so as to prevent the head passing through the slot and hence prevent the first and second members from being decoupled from each other.

The second member 34 is configured to have portions that engage with the hooks 30 on the isolation valve assembly 12 so that when engaged the mounting assembly 6 is unable to move in a direction away from the upstream face of the isolation valve assembly 12. The second member 34 may be a generally plate-like member that is arranged in a plane parallel to the first member 32. It may be portions of this plate-like part that engage the hooks 30. However, the upper edge of the second member 34 may comprise a flanged portion 46 that extends substantially orthogonal to the first member 32. This flanged portion 46 may be configured to hang on an upwardly directed surface of the isolation valve assembly 12, so as to help locate the mounting assembly 6 in the correct vertical location -10 -relative to the isolation valve assembly 12. Similarly, a lateral side edge of the second member 34 may comprise a flanged portion 48 that extends substantially orthogonal to the first member 32. This flanged portion 48 may be configured to abut a lateral side surface of the isolation valve assembly 12, so as to help locate the mounting assembly 6 in the correct lateral location relative to the isolation valve assembly 12.

As can be seen in Fig. 4A, the second member 34 has an opening therethrough such that the ion source enclosure 2 is able to abut and seal against the first member 32 The second member 34 may be substantially C-shaped in order to provide this opening. In other words, the second member 34 may have one side that is joined at its two ends to two substantially orthogonal sides so as to define an opening therein that is only partially enclosed by the sides of the second member 34. The three sides may include the top and bottom sides joined together by only one lateral side.

The mounting assembly 6 may also comprise one or more retaining member 50 that is configured to be selectively engagable with the isolation valve assembly 12 in a manner such that the mounting assembly 6 cannot move relative to the isolation valve assembly 12 in the direction required for the mounting assembly 6 to disengage from the hooks 30. In the depicted embodiment the one or more retaining member 50 is a screw threaded fastener on the mounting assembly 6 that has a screw thread for engaging a cooperating screw-threaded recess in the isolation valve assembly 12. The screw-threaded fastener may be configured to be operated by hand and without the need of any tools, e.g. such as a screwdriver. The screw-threaded fastener 50 may be provided so as to extend through the lateral flange 48 on the mounting assembly 6 and into the lateral side of the isolation valve assembly 12, when engaged therewith. It will, of course, be appreciated that the fastener 50 may be any other type of fastener or mechanism suitable for preventing the mounting assembly 6 moving relative to the isolation valve assembly 12 in the direction required for the mounting assembly to disengage from the hooks 30.

Fig. 4B shows a view of a section through the region in Fig. 4A that is enclosed by a dashed rectangle. The relationship between the first and second members 32,34 of the mounting assembly 6 is more clear from this view. As described above, the first and 30 second members 32,34 of the mounting assembly 6 may be coupled to each other by protrusions 42 of the first member 32 extending through slots 44 in the second member 34, such that the second member 34 is able to be moved relative to the first member 32. The opening 52 in the second member 34, for allowing the ion source enclosure 2 to abut and seal against the first member 32, is more easily visible in this view. The retaining member 50 for releasably engaging the recess 54 in the isolation valve assembly 12 is also shown.

Fig. 4B also shows the configuration of the hooks 30 in more detail. Each hook 30 comprises a recessed slot 56, extending into the hook 30 in a direction substantially orthogonal to the orifices 28,36 in the isolation valve assembly 12 and mounting assembly 6. The recessed slot 56 extends from a mouth at the lateral side of the hook 30 to a base inside the hook. The upstream surface 58 of the slot 56 may be arranged at an angle to said orthogonal direction (at least in the vicinity of the mouth of the slot) such that when the second member 34 is pushed into the slot 56, the second member rides along the upstream side 58 of the slot and is driven in the downstream direction towards the isolation valve assembly 12. Alternatively, or additionally, the upstream side of each portion of the second member 34 that is to be inserted into the hook 30 may be arranged at an angle to said orthogonal direction such that when the second member is pushed into the slot 56, the second member 34 rides along the upstream side of the slot 56 and is driven in the downstream direction towards the isolation valve assembly 12. In other words, the mouth of the slot 56 and/or the edge of the second member 34 that is to be inserted into the slot may be tapered in a manner such that when the second member 34 is inserted into the slot 56 the second member is driven towards the isolation valve assembly 12. The downstream side of the slot 56 may also taper outwardly in the downstream direction so as to help guide the second member 34 into the slot. It will be appreciated that alternative hook configurations may be provided. For example, the slot 56 need not contact the downstream side of the second member 34 when the second member is in the slot and may instead be spaced apart therefrom.

The operation of the mounting assembly will now be described in more detail. Figs. 4A and 4B show the mounting assembly 6 whilst in a position in which it is mounted on the isolation valve assembly 12. The ion source enclosure 2 is connected to the upstream side of the mounting assembly 6, although this is not shown so that the mounting assembly 6 is more clearly visible. This configuration enables ions generated in the ion source enclosure 2 to pass through the orifice 36 in the first member 32 of the mounting assembly 6, through the isolation valve assembly 12 and into the vacuum chambers 8,10 of the spectrometer. When it is desired to remove the ion source enclosure 2 from the spectrometer, the isolation valve in the isolation valve assembly 12 is closed and the ion source enclosure 2. may be vented so as to allow it to rise to atmospheric pressure The retaining member 50 located on the second member 34 of the mounting assembly 6 is then unfastened, such as by unscrewing, from the isolation valve assembly 12 so that they are disconnected from each other. Once the fastening member 50 has been unfastened, the second member 34 is then slid out of the recesses 56 in the hooks 30, e.g. by pulling the head of the fastening member 50 or by pulling the flange 48. At this point, the first member 32 may not be able to move along with the second member 34, e.g. because it is still urged against the seal 26 on the isolation valve assembly 12 (and/or because one of the hooks 30 may be blocking such sliding movement). However, this does not prevent the second member 34 from being able to slide out of the hooks 30 because the second member 34 is able to move relative to the first member 32 by virtue of their coupling, i.e. the slots 44 and protrusions 42. Once the second member 34 has been removed from the recessed slots 56 in the hooks 30, the mounting assembly 6 (and the ion source enclosure 2 mounted thereto) are able to be moved away from the isolation valve assembly 12.

It will be appreciated that the configuration of the mounting assembly 6 enables the ion source enclosure 2 to be removed simply and easily, requiring access to only a small region of the mounting assembly 6.

When it is desired to remount the ion source enclosure 2 on the isolation valve assembly 12 of the vacuum housing 4, the mounting assembly 6 (and ion source enclosure -12- 2 attached thereto) is presented to the upstream end of the isolation valve assembly 12 such that the orifice 36 in the first member 32 is aligned with the opening 28 into the isolation valve assembly 12. The second member 34 of the mounting assembly 6 may first have been slid to the right, so that it can be pushed passed the heads of the hooks 6.

Alternatively, the upstream end 60 of the hook 30 may be profiled at an angle such that as the mounting assembly 6 is pushed passed the hooks 30, the second member 34 rides along the profiled surface 60 and is pushed laterally outwards so that the second member 36 slides laterally outwards relative to the first member 34. When the first member 32 is in the desired location against the isolation valve assembly 12, the second member 34 of the mounting assembly 6 is then slid relative to the first member 32 such that the second member 34 enters the recesses 56 in the hooks 30. Abutments may be provided on the isolation valve assembly 12 so as to prevent the first member 32 from sliding during this step. For example, the first member 32 may abut against the base of one or more hooks 30 so that it cannot slide laterally. However, it is envisaged that the seal 26 contacting the first member 32 will prevent it from moving.

As described above, the internal surfaces of the recessed slots 56 and/or the external surfaces of the second member 34 may be configured such that as the second member 34 is slid laterally into the recessed slots 56, the second member 34 rides along the upstream surfaces of the recessed slots 56 in a manner such that the second member 34 is urged in a direction towards the isolation valve assembly 12. This movement of the second member 34 pushes the first member 32 and so causes the first member 32 to be forced against the seal 26 on the isolation valve assembly 12 so as to compress the seal 26 and provide a gas-tight seal therewith. The retaining member 50 is then screwed into the recess 54 in the isolation valve assembly 12 so as to prevent the second member 34 from moving out of the recessed slots 56 in the hooks 30. The isolation valve in the isolation valve assembly 12 may then be opened and the spectrometer may be used to analyse ions generated in the ion source enclosure 2.

Although the present invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.

For example, although the mounting assembly 6 has been described as comprising two members 32,34 that are slidably coupled to each other, it is contemplated that in less preferred embodiments the mounting assembly 6 may instead be a single member. Such embodiments may be provided, for example, by configuring the outer perimeter of the mounting assembly 6 such that all of the hooks 30 engage the outer perimeter of the mounting assembly 6. Alternatively, if a hook 30 protrudes through the mounting assembly 6 then an aperture can be provided in the mounting assembly 6 such that the mounting assembly 6 is able to be slid laterally relative to the hook and removed over the head of the hook. However, the two part mounting assembly is preferred as it avoids the first member 32 of the mounting assembly 6 from being slid along the seal 26 on the isolation valve assembly 12.

-13 -Although embodiments have been described in which the hooks 30 are provided on the vacuum housing 4 (i.e. isolation valve assembly 12) and the mounting assembly 6 is attached to the ion source enclosure 2, it is contemplated that the mounting assembly 6 may be fixed to the vacuum housing 4 and that the hooks make be provided on the ion source enclosure 2.

It is contemplated that the mounting assemblies described herein may be used to mount the ion source enclosure 2 to components of the vacuum housing 4 other than the isolation valve assembly 12. For example, the vacuum housing 4 may not have an isolation valve 12 in the first vacuum chamber 8.

Although embodiments have been described in which an ion source enclosure 2 is mounted to the mounting assembly 6, it is contemplated that the mounting assembly 6 may be used to mount any two components of the spectrometer together. -14-

Claims

Claims: 1.A mass and/or ion mobility spectrometer comprising: an ion source enclosure; a vacuum housing; and a mounting assembly for mounting the ion source enclosure to the vacuum housing; wherein the mounting assembly and vacuum housing are configured with cooperating elements that interlock when the mounting assembly and vacuum housing are in a first position relative to each other so as to prevent the mounting assembly being moved in a first direction away from the vacuum housing, and wherein the cooperating elements are configured such that when at least part of the mounting assembly is slid relative to the vacuum housing in a second, orthogonal direction and to a second, different position, the mounting assembly is able to be moved in the first direction away from the vacuum housing.
2. The spectrometer of claim 1, wherein the cooperating elements are configured such that said at least part of the mounting assembly is able to be moved relative to the vacuum housing in an opposite direction to the second direction and back to the first position so that said cooperating elements interlock and the mounting assembly is not able to be moved in the first direction away from the vacuum housing.
3. The spectrometer of claim 1 or 2, wherein the vacuum housing comprises an orifice in an upstream end thereof, for receiving ions from the ion source enclosure, and a seal surrounding this orifice; wherein said cooperating elements are configured such that when said at least part of the mounting assembly is slid relative to the vacuum housing in a direction opposite to the second direction and back to the first position, the mounting assembly is forced against said seal so as to compress it.
4. The spectrometer of any preceding claim, wherein the cooperating elements comprise at least one hook arranged on the vacuum housing that has at least one respective recess in it, and when said at least one recess is configured to receive the mounting assembly when said at least part of the mounting assembly is slid in a direction opposite to said second direction and into said first position.
5. The spectrometer of claim 4, wherein the vacuum housing comprises an orifice in an upstream end for receiving ions from the ion source enclosure and a seal surrounding the orifice; and wherein the at least one hook and mounting member are configured such that, when the mounting assembly is slid in a direction opposite to said second direction -15 -and into the at least one recess in the at least one respective hook, the mounting member is urged in a direction opposite to said first direction such that it compresses the seal.
6. The spectrometer of claim 5, comprising at least two or at least three of said hooks, wherein the hooks are spaced apart circumferentially around the outside of the seal.
7. The spectrometer of claim 6, wherein the hooks are spaced equidistantly around the circumference of the seal
8. The spectrometer of any one of claims 4-7, comprising a plurality of said hooks, wherein the recesses of the hooks are arranged on the same side of the hooks and configured so that the mounting assembly can slide in the second direction and out of the hooks simultaneously, and can be slid in the opposite direction and into the recesses simultaneously.
9. The spectrometer of any preceding claim, wherein the mounting assembly comprises: a planar part having opposing major surfaces for mounting against the ion source enclosure and the vacuum housing; and (i) a first flange that is substantially orthogonal to the planar part and configured to hang on an upwardly directed surface of the vacuum housing when the mounting assembly is in the first position; and/or (ii) a second flange that is substantially orthogonal to the planar part and configured to abut a vertical surface of the vacuum housing when the mounting assembly is in the first position.
10. The spectrometer of any preceding claim, comprising a fastening member for releasably fastening the mounting assembly to the vacuum housing such that it is unable to be slid in the second direction.
11. The spectrometer of claim 10, wherein the fastening member is a screw that screws the mounting assembly to the vacuum housing.
12. The spectrometer of claim 11, wherein the screw is an elongated screw and the vacuum housing has a cooperating elongated recess for receiving the screw, wherein the axes of the screw and recess are in the second direction when the mounting assembly and vacuum housing are interlocked.
13. The spectrometer of any preceding claim, wherein the mounting assembly 40 comprises: a first member having a planar part comprising opposing major surfaces for mounting against the ion source enclosure and the vacuum housing; and -16 -a second member that is coupled to said first member such that the second member can slide relative to the first member whilst coupled thereto; wherein the second member and vacuum housing comprise said cooperating elements.
14. The spectrometer claim 13, wherein one of the first and second members comprises at least one slot, and the other of the first and second members comprises at least one respective protrusion that is located in said slot such that the at least one protrusion is able to slide within the slot to enable the second member to move relative to the first member.
15. The spectrometer of claim 14, wherein each of the at least one slots is elongated in the second direction.
16. A mounting assembly for mounting an ion source enclosure to a vacuum housing of a mass and/or ion mobility spectrometer, the mounting assembly comprising: a first member having a planar part comprising opposing major surfaces for mounting between and against the ion source enclosure and the vacuum housing; and a second member that is coupled to said first member such that the second member can slide relative to the first member whilst coupled thereto.
17. A mounting assembly for mounting first and second components of a mass and/or ion mobility spectrometer together, the mounting assembly comprising: a first member having a planar part comprising opposing major surfaces for mounting between and against the first and second components; and a second member that is coupled to said first member such that the second member can slide relative to the first member whilst coupled thereto.