WO2001046677A2

WO2001046677A2 - Irradiating device with highly flexible membrane bellows

Info

Publication number: WO2001046677A2
Application number: PCT/EP2000/011207
Authority: WO
Inventors: Christoph Biedermann; Rainer Radtke; Simon Deuchler
Original assignee: MAX-PLANCK-Gesellschaft zur Förderung der Wissenschaften e.V.; Bestec Gmbh
Priority date: 1999-12-22
Filing date: 2000-11-13
Publication date: 2001-06-28
Also published as: DE19962198A1; EP1240505A2; DE19962198C2; WO2001046677A3

Abstract

The invention relates to an irradiating device (100) for irradiating a sample (21) in a sample chamber (20), comprising an irradiating source (10) and a detector device (30) which are each connected to a sample chamber (20) in a gas tight manner, in addition to a slewing device (40) which enables the irradiation source (10) and/or the detector device (30) to be swiveled relative to the sample (21). The irradiation source (10) and/or the detector device (30) can be connected to the sample chamber (20) via a flexible bellow connector (50). The invention also relates to a swivel connecting element in order to connect housing components in a gas tight manner. Said housing components can be swiveled towards each other.

Description

Irradiation facility with a highly flexible membrane bellows

The invention relates generally to a device for irradiating a sample in a sample chamber at predetermined irradiation angles and for observing the sample or for detecting scattered radiation emanating from the sample at predetermined observation angles, the pressure chamber in the sample chamber being different from the surroundings. The invention also relates to a swivel connection element for components of a system for irradiation or scattered radiation measurement on a sample or for observing the sample at adjustable angles.

In the case of a large number of physical examinations of solids, surfaces, gases or in the case of radiation analyzes, it is necessary to pivot a detector around the center of a scattering or dispersing element in order to observe scatter-dependent scatter signals at the respective observation angle. The dispersing element can be, for example, a sample to be examined with X-ray radiation, light or particle radiation or a target for the energy-dispersive scattering of a radiation to be analyzed. If the investigation has to be carried out under vacuum conditions because of the type of radiation used, the technical implementation of the experimental setup with radiation sources or detectors which can be pivoted relative to one another is problematic. For example, turntable arrangements are known in which the detector is pivoted in a vacuum on an outer ring of a turntable, in the center of which a dispersing element is arranged in a stationary manner. The disadvantages of the turntable arrangement are that the requirements Le gtgangigkeit and vacuum tightness can not be met simultaneously well. For a smooth-running turntable, compromises in terms of vacuum tightness have to be made. To remedy this, a multi-differentially pumped seal of the moving parts and the use of materials with a low static friction and a low desorption rate can be provided. However, the overall structure of the rotating arrangement is complicated. Another disadvantage of the turntable arrangement is the limited accuracy of the swivel angle setting.

In another variant of the rotating arrangements previously used, a so-called jacket shield seal is used. A fixed sample chamber with the dispersing element has a slot in the receiving plane. This slot is sealed by a metal tape pressed in from the outside with a small opening to the receiver. With this technology too, the mechanical and vacuum requirements are high and difficult to adapt to special applications.

The object of the invention is to provide an improved irradiation device for specimen irradiation or specimen observation (or scattered radiation detection), in particular under ultra-high vacuum conditions, with which the disadvantages of the conventional rotary arrangements are overcome and with which, in particular, smooth and precise angle adjustment is possible without impairing the vacuum , The object of the invention is also to create a new type of swivel connector element (or: vacuum connector element) for the gas-tight connection of components of an irradiation device with one pivotable radiation source and / or detector device.

These tasks are solved by an irradiation device with the features according to claim 1 and a vacuum connecting element with the features according to claim 8. Advantageous embodiments and applications of the inventions result from the dependent claims.

The basic idea of the invention is, in the case of an irradiation device for irradiating a sample in an evacuated sample chamber, to which a radiation source and a detector device are each connected in a vacuum-tight manner, the radiation source and / or the detector device being pivotable relative to the sample with a pivoting device, the radiation source and / or to connect the detector device to the sample chamber via a flexible, gas-tight bellows. In the sample chamber, the radiation source and the detector device there is an overpressure or underpressure with respect to the environment. B. evacuated. The detector device is generally used to observe the sample or to detect scattered radiation from the sample.

The bellows used according to the invention is a membrane bellows, at the ends of which a flange is provided for gas-tight (in particular: vacuum-tight) attachment to the sample chamber or the radiation source and / or the detector device. To significantly expand the functionality, a membrane bellows is preferably used, which has one or more of the following modifications compared to a conventional membrane bellows.

According to a first embodiment of the invention, at least one of the flanges has a welding collar which protrudes into the sample chamber or radiation source and / or detector device via a reference plane which is formed by the flange. The corresponding end of the membrane bellows is attached to the weld-on collar and is thus advanced towards the sample chamber, radiation source or detector device. When the membrane bellows is pivoted, the pivot point is accordingly advanced to the center of the sample. As a special advantage of the invention, this makes it possible to enlarge the viewing angle between the parts connected by the membrane bellows.

According to a further embodiment of the invention, the flange with the weld-on collar is provided on its rear side opposite to the free end with a rounding which runs along the inner edge of the flange. This increases the pivotability of the membrane bellows and the viewing angle through the bellows connection or prevents kinking on the inner edge of the flange.

According to a further design, the flange with the welding collar advanced is designed for countersunk screwing. The flange has, for example, threaded bores for receiving a screw connection with the adjacent sample chamber (or the detector or the radiation source). This allows a further increase in the pivotability of the diaphragm bellows or the viewing angle and the avoidance of injuries or undesirable bending of the bellows joint.

The bellows connection per se represents a swivel connection element according to the invention, which is suitable for various applications for connecting components of an irradiation device along certain beam directions The invention is applicable to a wide variety of research and technology tasks. With one or more bellows connections according to the invention, radiation devices can be set up, for example, which have a pivotable source and a fixed detector device, a pivotable source and a pivotable detector device or a stationary source and a pivotable detector device. The radiation source can generally be designed for electromagnetic radiation (visible light, X-rays, synchrotron radiation or the like) or for particle radiation (electron beams, atomic or ion beams or the like). Depending on the application, the sample itself is the subject of the investigation or radiation treatment or is also a target for the energy-dispersive deflection of the radiation. The sample can be formed by a solid body positioned in the sample chamber or by a gaseous sample beam guided through the sample chamber. In the latter case, the radiation device according to the invention can be designed, for example, to record scattering cross sections on the gaseous sample beam.

The invention has the following advantages. To build a bellows connection according to the invention, a membrane bellows is used which is commercially available per se, meets all ultra-high vacuum (UHV) requirements and can also be baked out. The bellows connection according to the invention enables an easily adjustable, shading-free, rectilinear beam connection between the radiation source and / or the detector device with the sample, it being possible to set all practical angle ranges of up to around 90 ° and beyond. The construction of the radiation device according to the invention is characterized by low technical complexity and the use of inexpensive components. The invention has one Wide range of applications from radiation analysis to solid-state analysis to sample processing and is fully compatible with common vacuum systems. The vacuum connecting element according to the invention also ensures maximum optical transmission when irradiating large-area samples.

The invention can be used not only with vacuum systems, but in general with all radiation or observation devices with an absolute or gas-specific (differential) pressure difference in relation to the environment.

Further advantages and details of the invention are described below with reference to the accompanying drawings. Show it:

FIG. 1: a schematic top view of an irradiation device according to the invention,

FIG. 2: a partial sectional view of a membrane bellows according to the invention,

FIG. 3: a schematic top view of an irradiation device according to the invention for energy-selective analysis of X-rays, and

Figure 4 is a partial sectional view of an irradiation device according to the invention with a conventional membrane bellows.

According to FIG. 1, an irradiation device 100 according to the invention comprises a radiation source 10, a sample chamber 20, a detector device 30, a swivel device 40 and at least one bellows connection 50. The radiation source Depending on the application, 10 is a source of electromagnetic radiation (e.g. lens, X-ray source, synchrotron radiation source) or a particle source (e.g. electron source, atomic source, neutron source, ion source) with certain emission properties or also a source with initially unknown radiation properties in an additional one, not in detail shown experimental setup. The radiation source 10 is connected to the sample chamber 20 via a straight, vacuum-tight connecting tube 11. The connecting tube 11 is directed towards the sample 21 in accordance with the direction of irradiation 12. Scattering or an emission excited by the radiation occurs on the sample 21. In the following, both types of radiation are referred to as scattered radiation. The connection between the radiation source and the sample chamber can be modified depending on the application and z. B. include through a window or any connection with "optical" beam steering elements.

The scattered radiation is detected with the detector device 30 illustrated in two positions A, B, which contains a suitable radiation receiver 31. The radiation receiver 31 is, for example, a light receiver (photodiode or photodiode arrangement), an X-ray detector or a particle detector. The detector device 30 can be swiveled along a circular swivel line 41 to detect the scattered radiation according to different observation directions 32a, 32b (see arrow direction). The swiveling device 40 comprises in particular a rail arrangement for guiding the detector device 30 along the swiveling line 41 and a drive for adjusting the detector device 30. The observation directions 32a, 32b can be adjusted over an angular range Δ which generally comprises up to 90 °, S with a suitable design of the bellows connection 50 can also be larger (eg 120 °).

The bellows connection 50 comprises a flexible membrane bellows 51, which has a sample-side flange 52 or a detector-side flange 53 at its ends. The membrane bellows 51 consists of a series of metal rings of small thickness, which are welded together alternately on their outer and inner edges. Two adjacent metal rings of the diaphragm bellows 51 form a pair of diaphragms. The metal rings have a thickness such that approx. 0.7 mm per pair of membranes, and are preferably made of stainless steel.

The flexible diaphragm bellows used to construct the bellows connection according to the invention has the following important deformation properties. If the diaphragm bellows 51 is clamped at its ends along differently aligned reference planes in accordance with the position of the flanges mentioned, it performs a combined deformation which consists of two opposite angular displacements. The deformation takes place in such a way that the membrane bellows 51 minimizes its surface. An evacuated diaphragm bellows (UHV in the interior of diaphragm bellows 51) opposes each lateral and angular deformation with a restoring force. The restoring force is formed so that the diaphragm bellows is aligned as straight as possible. A membrane bellows used in a bellows connection according to the invention is characterized in that the lateral or angular restoring force is less than the axial force which leads to the linear deformation of the membrane bellows. The consequence of this is that when the clamped ends of the diaphragm bellows are pivoted, only a minimal number of diaphragm pairs take part in a deformation, but this with their maximum Swivel angle. The other membrane pairs, however, remain aligned so that the membrane bellows remains straight. The number of membrane pairs involved in the deformation depends on the material and dimensions.

An important and unexpected feature of the invention is therefore that the bellows connection based on a highly flexible membrane bellows provides a vacuum-tight and largely straight connection between the sample chamber 20 and the detector device 30, each of which corresponds to the desired direction of observation (eg 32a, 32b) can be set. In order to achieve the largest possible swiveling range Δ, special precautions are taken on the flange 52 on the sample side, which are explained in detail below with reference to FIG.

In the embodiment of an irradiation device 100 illustrated in FIG. 1, the radiation source 10, the sample chamber 20 and the swivel device 40 are fixed relative to one another, while the detector device 30 is movable. In alternative embodiments of the invention it can be provided that the radiation source 10 is also connected to the sample chamber 20 via a bellows connection. The detector device 30 can also be fixed in place or can be completely omitted for certain radiation tasks that do not depend on the detection of scattered radiation (e.g. ion bombardment of semiconductor surfaces).

Details of the sample-side flange 52 of the bellows connection 50 are illustrated in FIG. 2. At the end of the membrane bellows 51, the sample-side flange 52 is welded on. The sample-side flange 52 forms a forward welding collar and projects into the attachment flange 22 of the sample chamber 20 at the free end with a circumferential step projection 54 m. At the ledge 54 is the end of the Membrane bellows 51 welded on. The membrane bellows 51 ends in the sample chamber 20 beyond the reference plane, which is formed by the flange connection between the attachment flange 22 and the flange 52 on the sample side. As a result, the bellows connection 50 can be attached to the sample chamber 20 such that the sample 21 is positioned centrally at the end of the membrane bellows 51. The center Z of the bellows rotary movement thus coincides essentially with the position of the sample 21 in the direction of irradiation 12. The reference plane formed by the flange connection is oriented obliquely with respect to the direction of irradiation 12. The direction of irradiation 12 runs through the attachment flange 22 or the flange 52 (see FIG. 1). Reference numeral 56 indicates an enlarged representation of a pair of membranes.

To enlarge the traversable angular range Δ, the flange 52 on the sample side is provided with a rounded portion 55 on its inner edge. The rounding 55 has a radius of curvature which is selected depending on the application for optimal use of the swivel range and is, for example, around 25 mm. In addition, the screw connection 57 is recessed with the adjacent flange. The flange 52 has an internal thread for screw connection with the shoulder flange 22. A mutual hindrance of the bellows and flange or an injury to the bellows by protruding bolts or nuts is avoided.

FIG. 3 shows an irradiation device according to the invention using the example of a Bragg crystal spectrometer. Starting from a radiation source (not shown), a primary beam 13 to be analyzed strikes the sample 21 in the sample chamber 20 along the irradiation direction 12 via an attachment flange 23. The sample 21 is a crystal (eg quartz), which acts as a target for diffraction of the primary beam 13 serves. The sample 21 is arranged pivotably in the sample chamber 20 in order to optimize the crystal orientation in relation to the energy range of the primary beam to be detected. The axis of rotation Z of the sample 21 coincides with the pivot axis of the membrane bellows 50. The membrane bellows 50 is connected to the sample chamber 20 via the sample-side flange 52 and the attachment flange 22, as is illustrated in FIG. 2.

The sample chamber 20 is in the form of a half-shell (hemisphere) with a diameter corresponding to the diameter of the flange 52 with the membrane bellows advanced. This ensures that the detector can observe a maximum target area in all swivel positions.

The detector device 30 is set in accordance with a predetermined observation direction 32. The detector device 30 comprises in particular an X-ray detector 31, an extension bellows 33 and an attachment flange 34 which is connected to the detector-side flange 53 of the bellows connection

50 is connected. With the extension flange 31, the distance between the detector 31 and the sample 21 is extended in order to achieve an improvement in the resolution in the scattered radiation analysis.

The diaphragm bellows 51 is a highly flexible, corrosion-resistant diaphragm bellows made of the material AM 350 (manufacturer: VAT Deutschland GmbH) with a nominal width of 150 mm and a leak rate <10 ^"9 mbar '1 / s. The flange on the detector side

51 is a DN 150 Conflat flange. The flange 52 on the sample is also a DN 150 Conflat flange, which, however, is modified as described above by attaching the welding collar and the rounding. Figure 3 illustrates an important advantage of the invention. The scattered radiation from the entire area of the sample 21 irradiated with the primary beam 13 is directed onto the detector device 30 without a shadow. The shadow clearance is ensured, even with relatively large samples with characteristic dimensions of up to 10 ^'10 cm ^2. The inside diameter of the membrane bellows is around 180 mm. In the relaxed state, the length of the membrane bellows 51 is around 25 cm.

It is emphasized that generally the use of a membrane bellows as a connecting element between pivotable parts of an irradiation device is the subject of the invention, even if restrictions in terms of functionality have to be accepted when using a conventional bellows. This is illustrated in FIG. 4, which schematically shows the structure according to FIG. 3 with a conventional bellows. Without a forward pivot point or without rounding on the flange back side, there is a reduced viewing angle or shading 35 on the detector 31. In addition, there is a risk of a bellows injury on the screw connections 57 above.

The radiation device according to the invention can generally be used in all systems in which a radiation source and / or a detector device are to be pivoted with respect to a fixed axis of rotation over a large swiveling range, with none between the radiation source and the sample or between the sample and the detector device The internal gas pressure or vacuum in the system breaks. Preferred applications are in the construction of a Bragg crystal spectrometer, a spectrometer for angle-resolved particle registration and in all arrangements in which the conventional one Turntable construction with an angular range of around 100 ° is to be replaced.

In the case of modified designs of the bellows connection, it can be provided that the membrane bellows consists of other metals (e.g. aluminum) or plastic (e.g. PTFE), has dimensions other than those given here by way of example and / or has a rectangular or otherwise shaped cross section has.

Claims

claims

1. Irradiation device (100) for irradiating a sample (21) in a sample chamber (20) with

- A radiation source (10) and a detector device (30), which are each gas-tightly connected to the sample chamber (20), and

- A swivel device (40) with which the radiation source (10) and / or the detector device (30) can be pivoted relative to the sample (21), characterized in that the radiation source (10) and / or the detector device (30) with the Sample chamber (20) is connected via a flexible bellows connection (50).

2. Irradiation device according to claim 1, wherein the bellows connection (50) is formed by a connecting element with a membrane bellows, at the ends of which a flange (52, 53) for gas-tight attachment to the sample chamber (20) or the radiation source (10) and / or the detector device (30) are provided, at least the flange (52) having a forward welding collar which extends over a reference plane which is formed by the flange, the sample chamber (20) or the radiation source (10) and / or the detector device (30) protrudes.

3. Irradiation device according to claim 2, wherein the flange (52) protrudes into the sample chamber (20) so that the sample (21) is arranged in the center (Z) of the welding collar.

4. Irradiation device according to one of claims 1 to 3, which is constructed as a spectiometer, the radiation source (10) being a primary beam (13) to be analyzed, the Prcbf (21) a relative to the radiation source (10) positioned with a fixed axis of rotation and the detector device (30) is arranged pivotable relative to the sample (21).

5. Irradiation device according to claim 4, which is constructed as a crystal spectrometer

6. Irradiation device according to one of claims 1 to 5, wherein the sample chamber (20) has the shape of a half-shell with a diameter corresponding to the diameter of the flange (52).

7. Irradiation device according to one of claims 1 to 6, in which in the sample chamber (20) there is a pressure difference from the environment.

8. Schwenkverb expansion element (50), which is formed by a membrane bellows (51), at the ends of which a flange (52, 53) for gas-tight attachment to mutually pivotable housing parts (22, 23) of an irradiation system is provided, characterized in that at least one of the flanges (52) has a weld-on collar which projects into the respective housing part via a reference plane which is formed by the flange.

9. swivel connector element according to claim 8, wherein the flange (52) has at its free end a circumferential step projection (54) which, in the assembled state, protrudes into an attachment flange (22) of the respective housing part.

10. pivot connection element according to claim 9, wherein the flange (52) on its rear opposite to the free end has a rounded portion (55) which runs along the inner edge of the flange (52).

11. Swivel connection element according to one of claims 8 to 10, wherein the flange (52) with the forward welding collar has threaded bores for receiving a screw connection with the adjacent housing part.

12. Swivel connection element according to one of claims 8 to 11, wherein the diaphragm bellows (51) consists of a plurality of metal or plastic rings which are successively connected gas-tight alternately on their inner and outer edges.

13. Use of a swivel connection element according to one of claims 8 to 12 as a bellows connection in an irradiation device according to one of claims 1 to 7.