FIELD OF THE INVENTION

The present invention relates to an instrument that comprises a vacuum chamber comprising an interior space for containing depressurized fluid, and a mechanism for depressurizing fluid in the interior space of the vacuum chamber.

BACKGROUND OF THE INVENTION

Generally, analytical instruments such as mass spectrometers depend on an analytical technique including detecting compounds of interest such as drugs, explosives, etc. based on their mass-to-charge ratio (molecular mass). Key components in such kind of instruments are a vacuum chamber, an ion source, mass spectrometer electrodes, and an ion detector. A controlled leak is provided at the inlet of the vacuum chamber to introduce a sample to the vacuum chamber. The sample is ionized by the ion source that is housed in the vacuum chamber and ions travel in the vacuum chamber under the influence of electric fields generated by mass spectrometer electrodes. Said sample ions are separated based on their mass to charge ratio and are detected at the ion detector.

A mass spectrum is usually created wherein the horizontal axis represents the mass and wherein the vertical axis represents the signal intensity/current. Vacuum is needed for the mass spectrometer operation so that a chance that the sample ions collide with neutral (air) molecules and with each other is minimized.

Usually, vacuum chambers which are made of high-grade stainless steel are widely in use and provide excellent vacuum characteristics. However, in the case of the mass spectrometer with all its components, this is at the cost of high weight. Low weight metals, such as aluminum, are occasionally in use, but the main problem of many parts made of aluminum is a low wear resistance. In that way, said parts may become susceptible to deformations with time. This will result in leakage problems within the vacuum chamber, especially in connection flanges at which the vacuum chamber is connected to the other components of the analytical instrument. Any leakage in the vacuum chamber will affect analysis and/or measurements of the analytical instrument.

In the past there have been several attempts to use carbon composites in the vacuum chamber. However, it was reported that the composite vacuum chambers were very fragile in those cases. Also, it is impossible to achieve a deep vacuum, since the carbon fiber composites start to release its resin components which will interfere with the measurement of the sample.

SUMMARY OF THE INVENTION

It is an objective of the present invention to design a vacuum chamber so as to be suitable for enabling an improved and lightweight portable structure of an instrument including the vacuum chamber, and to have improved resistance and improved durability to interior pressures well below ambient pressure.

Aspects of the present invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features from the independent claim as appropriate and not merely as explicitly set out in the claims.

At least the abovementioned objective is achieved by an instrument comprising:

- a vacuum chamber comprising an interior space for containing depressurized fluid, and

- a mechanism for depressurizing fluid in the interior space of the vacuum chamber, wherein a wall of the vacuum chamber delimiting at least a portion of the interior space includes:

- a layer of carbon fiber reinforced thermoset having a thickness in a range of 1-10 mm,

- a first layer of ceramic material having a thickness in a range of 40-60 pm,

- a layer of aluminum having a thickness in a range of 0.5-10 mm, and

- a second layer of ceramic material having a thickness in a range of 40-60 pm, wherein the first layer of ceramic material is positioned between the layer of carbon fiber reinforced thermoset and the layer of aluminum, wherein the layer of aluminum is positioned between the first layer of ceramic material and the second layer of ceramic material, and wherein the second layer of ceramic material is positioned most to a side of an interior surface of the wall of the vacuum chamber.

Carbon fiber reinforced thermoset materials are widely used in aircrafts for various reasons including high moldability. The material and the lamination and orientation in the fiber direction result in a coefficient of linear expansion of the carbon fiber reinforced thermoset material being less than that of metals (less than 1/170 of conventional stainless steel and less than one-fifth of Invar). In that way, the layer of carbon fiber reinforced thermoset prevents the wall of the vacuum chamber from being deformed without the use of any temperature adjustment.

Carbon fibers may be positioned in specific patterns or can be relatively short and randomly dispersed. In the case of long fibers being positioned in specific patterns, they can be aligned in a single direction or positioned in patterns designed to give two or three dimensional strength to the fiber reinforced thermoset. For example, the carbon fibers may be formed as a unidirectional sheet. These sheets may be layered onto each other in a quasi-isotropic layup, e.g. 0°, +60° or -60° relative to each other. Additionally, the carbon fibers may be formed as a bidirectional woven sheet. The mechanical properties of the carbon fiber reinforced thermoset may be tailored to the specific requirements of the vacuum chamber.

The carbon fiber reinforced thermoset material is strong enough to be used in aircrafts against any impacts. In terms of mechanical strength related to bending strength, its Young's modulus is approximately 1.4-fold of that of stainless steel. Its specific gravity is approximately one-fifth of that of stainless steel. Moreover, the carbon fiber reinforced thermoset material provides high vibration damping properties as compared to metals.

According to the invention, in the wall of the vacuum chamber delimiting at least a portion of the interior space of the vacuum chamber, the first layer of the ceramic material is arranged between the layer of carbon fiber reinforced thermoset and the layer of aluminum. The first layer of the ceramic material provides an adhesive bound between the layer of carbon fiber reinforced thermoset and the layer of aluminum. The layer of aluminum also guarantees the gas impermeability of the wall of the vacuum chamber.

Operation of the vacuum chamber may involve conditions where a high voltage of ± several kV is applied. In that case, it is most practical if the wall of the vacuum chamber includes an electroconductive material which is durable in the context of the depressurized interior space of the vacuum chamber. The second layer of the ceramic material is arranged on the layer of aluminum and is positioned most to a side of an interior surface of the wall of the vacuum chamber. In that way, the second layer of the ceramic layer may allow the layer aluminum to be durable and to not be deteriorated by pressure effects and high voltage effects.

The second layer of the ceramic material has a function as an electrical insulator which provides high wear resistance to the wall of the vacuum chamber. The second layer of the ceramic material is subjected to a pressure following from the presence of a depressurized fluid at the side of the interior surface of the wall of the vacuum chamber. In that way, the second layer of the ceramic material provides high stiffness, low porosity, poor conductivity, chemical resistance and low ductility in the depressurized environment.

The thickness of the second layer of ceramic material is in a range of 40-60 pm. In the case of the thickness being under 40 pm, there is a risk that the second layer of the ceramic material includes some pores and holes that may result in a chemical reaction between the layer of aluminum and the depressurized interior of the vacuum chamber. In the case of the thickness being above 60 pm, it may happen that air that is trapped in the second layer of ceramic material is released to the depressurized interior and may affect a predetermined pressure to be realized in the vacuum chamber.

In an embodiment of the instrument according to the invention, in the wall of the vacuum chamber, the layer of carbon fiber reinforced thermoset is bound to the first layer of ceramic material, wherein the layer of aluminum is bound to the first layer of ceramic material and the second layer of ceramic material.

The layer of the carbon fiber reinforced thermoset is bound on the layer of aluminum on which the first layer of ceramic is bound. One of the advantages of the invention is a possibility to bond the first layer of the ceramic material with the layer of carbon fiber reinforced thermoset and the layer of aluminum under moderate temperatures. This results in a very strong bonding to aluminum and/or carbon fiber without destroying the thermoset resin.

The second layer of ceramic material can be bound to the layer of aluminum such that porosity on the attachment between the second layer of the ceramic material and the layer of aluminum is prevented.

In an embodiment of the instrument, in the wall of the vacuum chamber, the layer of carbon fiber reinforced thermoset has a thickness in a range of 1-2 mm.

In an embodiment of the instrument, in the wall of the vacuum chamber, the layer of aluminum has a thickness in a range of 0.5-3 mm.

In an embodiment of the instrument, in the wall of the vacuum chamber, the layer of aluminum has a thickness in a range of 1-2 mm.

In an embodiment of the instrument, the mechanism for depressurizing the fluid is configured to reduce the pressure of the fluid in the interior space of the vacuum chamber to a pressure in a range of 10 ¹ mbar (10 Pa) and 10 ⁹ mbar (10 ⁷ Pa).

In an embodiment of the instrument, the mechanism for depressurizing the fluid is configured to reduce the pressure of the fluid in the interior space of the vacuum chamber to a pressure in a range of 10 ³ mbar (10 ^_1 Pa) and 10 ⁸ mbar (10 ⁶ Pa). ln an embodiment of the instrument, in the wall of the vacuum chamber, the ceramic material of the second layer of ceramic material has a hardness according to Vickers (HV) of at least 750.

In an embodiment of the instrument, at the side of the wall of the vacuum chamber other than the side where the layer of aluminum is present, the second layer of ceramic material is covered by a coating. In an embodiment of the instrument, the coating is selected from a group that includes a Teflon® coating, gold coating, copper, titanium and a diamond-like-carbon (DLC) coating.

The second layer of the ceramic material may be treated, for example, by coating the second layer of the ceramic material. Coatings may be applied to a side of the second layer of the ceramic material which is positioned most to the side of the interior surface of the wall of the vacuum chamber for reducing friction or increasing friction. The coatings which are suitable to reduce friction may be selected from a group that includes a Teflon® coating or a diamond-like-carbon (DLC) coating. The coatings which are suitable to increase friction may be a thermoplastic coating.

In an embodiment of the instrument, in the wall of the vacuum chamber, the ceramic material of the second layer of ceramic material is material prepared by plasma electrolytic oxidation of the aluminum.

In the manufacturing process of the vacuum chamber, especially of an object that is intended to make up the wall of the vacuum chamber, preferably the surface of the layer of aluminum may be partially treated with plasma electrolytic oxidation (PEO) to provide the second layer of the ceramic material. With said treatment, the object is provided, wherein the object comprises a carbon fiber reinforced thermoset coated with a ceramic material bound to aluminum. For ensuring an excellent adhesion between the layer of carbon fiber reinforced thermoset and the second layer of the ceramic material, the layer of aluminum of the object may be further treated by machining, grinding, anodization, plasma spray coating, flame spray coating, electric-arc spray coating, cold spray coating and/or plasma electrolytic oxidation.

The interior space of the vacuum chamber of the instrument may be configured to contain at least one item, for example in a manufacturing process of the item, wherein further components may be used in combination with the instrument to subject the item to one or more types of operation. In a practical example, an operation to be performed on an item positioned inside the vacuum chamber is particle cleaning. In such a case, a vacuum pressure prevailing inside the vacuum chamber may typically be in a range of about 10 ¹ mbar (10 Pa) to 10 ⁹ mbar (10 ⁷ Pa), depending on whether or not a purge gas is used. During the actual particle cleaning, the vacuum pressure in the vacuum chamber may be above 10 ⁹ mbar (10 ⁷ Pa), preferably between 10 ³ mbar (10 ¹ Pa) and 10 ⁸ mbar (10 ⁶ Pa).

The instrument according to the invention may particularly be an analytical instrument configured to perform an analysis of a sample, comprising:

- an ion source that is configured to create ions in the sample,

- electrodes which are configured to separate ions from the sample and to thereby provide separated ions,

- a detector that is configured to detect the separated ions, wherein the ion source, the electrodes, and the detector are positioned in the interior space of the vacuum chamber, and wherein the mechanism for depressurizing fluid in the interior space of the vacuum chamber comprises a vacuum pump in fluid communication with the interior space of the vacuum chamber.

In an embodiment, the analytical instrument is a mass spectrometer in which the vacuum chamber comprises a tube and at least four flanges which are attached to the tube, and in which the vacuum pump is arranged at a first flange of the vacuum chamber. The mass spectrometer further comprises:

- a pressure gauge that is arranged at a second flange of the vacuum chamber and configured to regulate fluid pressure in the vacuum chamber,

- an inlet that is arranged at a third flange of the vacuum chamber and configured to receive the sample to the interior space, and

- an electronic control unit that is arranged at a fourth flange of the vacuum chamber, wherein the detector is positioned most to the electronic control unit in the interior space.

In an embodiment of the instrument, the instrument is of a portable nature by having a weight of 20 kg or less.

Unlike vacuum chambers made of metal, the coefficient of linear expansion of a vacuum chamber included in the instrument according to the invention can be reduced to nearly zero. In that way, the vacuum chamber is nondeformable even when a temperature adjustment and control system is not used. Also, because of its light weight and high Young's module, any deflection in the vacuum chamber may be prevented.

Because of high vibration-damping property of the layer of carbon fiber reinforced thermoset, the vacuum chamber is not affected by external vibrations even when it is held perpendicularly and supported as a cantilever. Further, because of the high moldability of the layer of carbon fiber reinforced thermoset, the layer of carbon fiber reinforced thermoset can be formed into pipes of any diameter. Still further, by providing the layer of aluminum between the first and second layer of the ceramic material on top of the layer of carbon fiber reinforced thermoset, the same functionalities as a metal vacuum chamber are obtained while providing an out-gas suppression effect in the vacuum environment that uses a vacuum pump at a slow evacuation rate. In that way, even when high voltage is applied to the tube of the vacuum chamber, a prevention of vacuum discharge is ensured.

The instrument of the invention may be used in various applications, especially for applications involving the use of a vacuum chamber while at the same time requiring a light and wear resistant material (applications involving e.g. Particle Beamlines, electron microscopy vacuum chambers, semiconductor industry vacuum chambers).

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparent from the description of the invention by way of exemplary and non-limiting embodiments of an instrument that comprises a vacuum chamber and a mechanism for depressurizing fluid in an interior space of the vacuum chamber.

The person skilled in the art will appreciate that the described embodiments of the instrument according to the present invention are exemplary in nature only and not to be construed as limiting the scope of protection in any way. The person skilled in the art will realize that alternatives and equivalent embodiments of the instrument can be conceived and reduced to practice without departing from the scope of protection of the present invention.

Reference will be made to the figures on the accompanying drawing sheets. The figures are schematic in nature and therefore not necessarily drawn to scale. Further, equal reference numerals denote equal or similar parts. On the attached drawing sheets,

Figure 1 illustrates an analytical instrument comprising a vacuum chamber;

Figure 2 illustrates a tube of the vacuum chamber and four flanges which are attached to the tube; and

Figure 3 illustrates a cross-section of the tube of the vacuum chamber. DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 illustrates an analytical instrument 100 that is configured to perform an analysis of a sample. The analytical instrument 100 comprises a vacuum chamber 10 and a mechanism 20 for depressurizing fluid within the vacuum chamber 10.

For example, as shown in Figure 1 , the analytical instrument 100 may be a mass spectrometer that comprises the vacuum chamber 10 as mentioned, a vacuum pump 20, a pressure gauge 30, an inlet 40, and an electronic control unit 50. In view thereof, in the following, the analytical instrument 100 will be referred to as mass spectrometer 100.

The mass spectrometer 100 may further comprise an ion source configured to create ions in the sample, electrodes which are configured to separate ions from the sample and to thereby provide separated ions, and a detector that is configured to detect the separated ions. The ion source, the electrodes, and the detector may be positioned in an interior space 11 of the vacuum chamber 10. The detector may be positioned most to the electronic control unit 50 in the interior space 11.

Figure 2 illustrates the vacuum chamber 10. In the shown example, the vacuum chamber 10 comprises a tube 12 and four flanges 13, 14, 15, and 16 which are attached to the tube 12. In this configuration, the vacuum pump 20 may be arranged at a first flange

13 of the vacuum chamber 10, the pressure gauge 30 may be arranged at a second flange

14 of the vacuum chamber 10 and configured to regulate fluid pressure in the vacuum chamber 10, the inlet 40 may be arranged at a third flange 15 of the vacuum chamber 10 and configured to receive the sample to the interior space 11 , and the electronic control unit 50 may be arranged at a fourth flange 16 of the vacuum chamber 10.

In practical applications, a wall 17 of the vacuum chamber 10 may be subjected to pressure following from the pressure of the depressurized fluid in the interior space 11 of the vacuum chamber 10 being set by means of the vacuum pump 20 to a pressure in a range of 10 ¹ mbar (10 Pa) and 10 ⁹ mbar (10 ⁷ Pa). Unlike vacuum chambers made of metal, the coefficient of linear expansion of the vacuum chamber 10 may be reduced to nearly zero. In that way, the vacuum chamber 10 is practically nondeformable even without use of a temperature adjustment and control system.

Figure 3 illustrates the structure of the wall 17 of the vacuum chamber 10 at the position of the tube 12. The wall 17 of the vacuum chamber 10 includes a layer of carbon fiber reinforced thermoset 61 , a first layer of ceramic material 62, a layer of aluminum 63, and a second layer of ceramic material 64. The second layer of the ceramic material 64 is positioned at the side of an interior surface 18 of the wall 17 of the vacuum chamber 10. The layer of carbon fiber reinforced thermoset 61 has a thickness in a range of 1-10 m . Consequently, the layer of carbon fiber reinforced thermoset 61 is strong enough to resist a broad range of impacts. In terms of mechanical strength related to bending strength, the Young's modulus of the carbon fiber reinforced thermoset material is approximately 1.4-fold of that of stainless steel. Additionally, the carbon fiber reinforced thermoset material provides high vibration damping properties as compared to metals.

Further, the first layer of the ceramic material 62 has a thickness in a range of 40-60 pm, and the second layer of the ceramic material 64 has a thickness in a range of 40-60 pm as well. As shown in Figure 3, the first layer of the ceramic material 62 is arranged between the layer of carbon fiber reinforced thermoset 61 and the layer of aluminum 63. The first layer of the ceramic material 62 may provide an adhesive bound between the layer of carbon fiber reinforced thermoset 61 and the layer of aluminum 63.

The layer of aluminum 63 has a thickness in a range of 0.5-10 mm. The layer of the carbon fiber reinforced thermoset 61 may be bound on the layer of aluminum 63 on which the first layer of ceramic material 62 is bound. During a manufacturing process of the vacuum chamber 10, especially of an object that is intended to make up the wall 17 of the vacuum chamber 10, the first layer of the ceramic material 62 may be bound with the layer of carbon fiber reinforced thermoset 61 and the layer of aluminum 63 under moderate temperatures. This may result in a very strong bonding to aluminum and/or carbon fiber without destroying the thermoset resin in the layer of carbon fiber reinforced thermoset 61 .

During operation of the mass spectrometer 100, a high voltage of ± several kV is applied in the interior space 11 of the vacuum chamber 10. As the second layer of the ceramic material 64 is arranged on the layer of aluminum 63 and is positioned most to the interior surface 18 of the wall 17 of the vacuum chamber 10, the second layer of the ceramic layer 64 may allow the layer aluminum 63 to be durable in the context of an environment which is depressurized, and in which high voltage is applied. Also, the second layer of the ceramic material 64 may have a function as an electrical insulator which provides high wear resistance to the wall 17 of the vacuum chamber 10.

Because of high vibration-damping property of the layer of carbon fiber reinforced thermoset 61 , it may be achieved that the vacuum chamber 10 is not affected by external vibrations even when it is held perpendicularly and supported as a cantilever. Further, because of the high moldability of the layer of carbon fiber reinforced thermoset 61 , the layer of carbon fiber reinforced thermoset 61 can be formed into pipes of any diameter.

Still further, by providing the layer of aluminum 63 between the first and second layer of the ceramic material 62, 64 on top of the layer of carbon fiber reinforced thermoset 61 , the same functionalities as a metal vacuum chamber are obtained while providing an out-gas suppression effect in the vacuum environment that uses the vacuum pump 20 at a slow evacuation rate. In that way, even when high voltage is applied to the interior space 11 of the vacuum chamber 10, prevention of vacuum discharge is ensured.

The present invention can be summarized as relating to an instrument 100 that comprises a vacuum chamber 10, wherein a wall 17 of the vacuum chamber 10 includes a layer of carbon fiber reinforced thermoset 61 having a thickness in a range of 1-10 mm, a first and a second layer of ceramic material 62, 64 having a thickness in a range of 40-60 pm, and a layer of aluminum 63 having a thickness in a range of 0.5-10 mm. The first layer of ceramic material 62 is positioned between the layer of carbon fiber reinforced thermoset 61 and the layer of aluminum 63. The layer of aluminum 63 is positioned between the first layer of ceramic material 62 and the second layer of ceramic material 64. The second layer of ceramic material 64 is positioned most to a side of an interior surface 18 of the wall 17 of the vacuum chamber 10.

It will be clear to a person skilled in the art that the vacuum chamber 10 of Figure 2 does not necessarily need to be provided with one tube 12 and four flanges 13, 14, 15, 16. The number of the tube 12 and the flanges 13, 14, 15, 16 could be any number that is suitable for a given application of the vacuum chamber 10. For example, the vacuum chamber 10 may comprise one tube 12 with five flanges or two tubes 12 with two flanges on each tube 12.

It will be also clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing but that several amendments and modifications thereof are possible without deviating from the scope of the present invention as defined by the attached claims. In particular, combinations of specific features of various aspects of the invention may be made. An aspect of the invention may be further advantageously enhanced by adding a feature that was described in relation to another aspect of the invention. While the present invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive.

The present invention is not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached claims. In the claims, the word “comprising” does not exclude other steps or elements, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference numerals in the claims should not be construed as limiting the scope of the present invention.

LIST of REFERENCE NUMERALS 100 Instrument

10 Vacuum chamber

11 Interior space of the vacuum chamber 12 Tube of the vacuum chamber

13, 14, 15, 16 Flanges of the vacuum chamber

17 Wall of the vacuum chamber

18 Interior surface of the wall of the vacuum chamber

20 Vacuum pump 30 Pressure gauge

40 Inlet

50 Electronic Control Unit

61 Layer of carbon fiber reinforced thermoplastic

62 First layer of ceramic material 63 Layer of Aluminum

64 Second layer of ceramic material