DE102006046688B3 - Cooling system, e.g. for super conductive magnets, gives a non-mechanical separation between the parts to be cooled and the heat sink - Google Patents

Abstract

The cooling system (100), e.g. for super conductive magnets, has a warm connection (101) with a thermal bond to the part (102) to be cooled and a cold connection (103) in a thermal bond with a heat sink (104). A heating tube (105), of a material with poor thermal conductivity, has one end at the hot connection and the other end with a mechanically released link at the cold connection, filled with a fluid (106) for circulation through a thermo-siphon effect. A connecting pipe (107) has one end within the hot tube and the tube is higher than the fluid level to pump out the fluid to give a thermal separation between the connections.

Description

• – einem warmen Verbindungselement, welches mit zu kühlenden Teilen einer Einrichtung thermisch verbunden ist,
• – einem kalten Verbindungselement, welches thermisch mit einer Wärmesenke verbunden ist,
• – einem Wärmerohr aus schlecht-wärmeleitendem Material, welches an einem ersten Ende mit dem warmen Verbindungselement und an einem zweiten Ende mit dem kalten Verbindungselement verbunden ist, und dessen Innenraum zumindest teilweise mit einer nach einem Thermosiphoneffekt zirkulierbaren Flüssigkeit gefüllt ist.

The invention relates to a refrigeration system with at least

• A hot connection element which is thermally connected to parts of a device to be cooled,
• A cold connection element which is thermally connected to a heat sink,
• - A heat pipe made of poor thermal conductivity material, which is connected at a first end to the hot connection element and at a second end to the cold connection element, and the interior of which is at least partially filled with a circulatory liquid according to a thermosiphon effect.

A refrigeration system with the above features, for example, from the DE 102 11 568 B4 out.

Cooling systems, eg cooling systems for superconducting magnets, often have so-called bath cooling. For such a bath cooling, a liquid refrigerant, eg helium, with a temperature of typically 4.2 K can be used. The DE 10 2004 060 832 B3 discloses an NMR spectrometer whose superconducting magnet coil system has bath cooling. The cooling system of the NMR spectrometer is designed such that a circulating refrigerant detects various elements of the NMR spectrometer in its circulation path. By such a refrigerant circulation, a plurality of elements of the NMR spectrometer with different temperature levels can be cooled by means of a single refrigerator.

For a bath cooling are however big Quantities of the corresponding refrigerant necessary. In a superconducting magnet continues to exist Possibility, that this, e.g. by crossing one for the corresponding superconducting material critical current or a critical magnetic field, its superconducting properties loses. In such a case, the superconducting material occurs a big one in the short term Heat development on. The resulting heat leads to a bath cooling a boiling of the refrigerant inside the cryostat. Large quantities of gaseous refrigerant leads to a rapid increase in pressure within the cryostat.

Around to address this problem while reducing the cost of the refrigerant to reduce cooling systems designed without a refrigerant bath. Such cooling systems can without any refrigerant get along. The cooling capacity is in this case only by solid-state heat conduction in the to be cooled Areas introduced. In such a cooling system, the areas to be cooled by a so-called solid state cryobus of e.g. Copper with a chiller be connected. One more way is to cool those Areas and the chiller to connect with a closed piping system, in which a small amount of refrigerant circulated. The advantage of such cooling systems without a refrigerant bath persists in that these easier on moving loads to be cooled are to be adapted as cooling systems, which is a refrigerant bath exhibit. cooling systems without a refrigerant bath are therefore especially for superconducting magnets are suitable for a so-called gantry, as they are be used in ion beam therapy for the fight against cancer. The Cooling capacity may typically be one in the cooling systems described above Chiller with a cold head in particular a Stirling cooler provided become.

A superconducting magnet, in which a cold head with its second stage is directly mechanically and thermally connected to the support structure of a superconducting magnet winding, goes, for example, from US 5,396,206 out. The necessary cooling capacity is introduced directly into the superconducting magnet windings in the aforementioned superconducting magnet by solid-state heat conduction. If, however, a cold head has to be replaced, for example, for maintenance purposes, the abovementioned cooling device for a superconducting magnet has a decisive technical problem. During the exchange process, air or other gases may freeze on the cryogenic contact surface, in this case the superconductive winding support structure. Ice formed at these points leads to a poor thermal connection of the subsequently re-inserted cold head with the support structure of the winding.

Around a freezing of gases at the cryogenic contact surfaces to can avoid These are heated to about room temperature. This leads in the Rule that the entire parts of a facility to be cooled, e.g. the entire superconducting windings of a magnet Room temperature must be brought, before the cold head can be replaced. Especially for large systems can such a warm-up hare and the subsequent one cooling phase take a long time. This leads to long downtime of the System. The warm-up and cooling phases to lead continue to be a big one Consumption of energy.

Alternatively, the freezing of ambient gases at the cryogenic contact surfaces can be avoided by purposely flooding the space around these contact surfaces with gas. However, this is expensive and leads to a large consumption of purge gas or vaporized for this purpose refrigerant.

EP 0 696 380 B1 discloses a superconducting magnet with a cryogen-free refrigeration system. The disclosed refrigeration system has a thermal bus of good thermal conductivity material such as copper, which is connected to the superconducting magnet. The thermal bus can still be connected to two cold heads. The two cold heads are arranged symmetrically to the thermal bus. They can each be approached from opposite sides to the thermal bus. In this way one or both cold heads can be brought into thermal contact with the thermal bus. The cooling capacity is introduced in accordance with one or both cold heads in the thermal bus.

To replace one of the two cold heads of the known system this can be moved back mechanically by the thermal bus, whereby the corresponding cold head is also thermally separated from the thermal bus. In this case, the cooling capacity is provided only by the one remaining cold head. An exchange of the retracted cold head can now be done without the superconducting magnet must be heated. At the in EP 0 696 380 B1 disclosed refrigeration system, the cold heads, however, must be carried out mechanically movable, which requires a variety of low-temperature components and a corresponding, possibly interference-prone mechanics.

JP 2000-146333 A discloses an apparatus and method for maintaining a cryocooler. Before exchanging a cryocooler or cold head, a corresponding identical cold head is pre-cooled in a bath with liquid nitrogen. By pre-cooling the identical cold head, the components of the cold head can be brought to a comparable temperature as the corresponding components to be replaced. In this way, the cryogenic conditions within a plant whose cold head is to be replaced, can be kept almost unchanged.

DE 102 11 568 B4 discloses a refrigeration system with two cold heads, which are connected via a piping system in which a refrigerant is circulatory according to a thermosiphon effect, connected to the parts to be cooled of a device. The piping system has a branch. At the ends of the branches there is a respective refrigerant space, which is connected to a cold head. Liquid refrigerant decreases, starting from one of these refrigerant chambers, gravity driven to the parts of the device to be cooled, at which the heat transfer takes place. Gaseous refrigerant in the piping system in turn rises to the two cold heads, where it is reliquefied. Such a cycle of the refrigerant may take place in the piping system both in the case where only one cold head is operating and in the case where both cold heads are operating. If the refrigeration system is dimensioned in such a way that a single cold head applies the cooling capacity necessary for the parts of the device to be cooled, another cold head can be exchanged during operation of the refrigeration system. To minimize thermal losses, the piping system between the branch and the refrigerant spaces, which are each connected to a cold head, made of poor thermal conductivity material. In this way, the losses can be limited by solid-state heat conduction. However, gaseous refrigerant will always rise to the point where there is no or cold head off. Thus, although the losses can be limited by solid-state heat conduction, but not the losses caused by circulating refrigerant.

DE 101 02 653 A1 discloses a mechanical thermal switch, which consists of a first cup-shaped metal body which can form-fit enclose a second metal body. The first metal body has for this purpose a free end, which can form a positive connection together with the outer jacket of the second metal body. In the first pot-shaped metal body, a fourth metal body is introduced, a third metal body surrounds the cup-shaped first metal body from the outside surrounding. Upon heating of the fourth metal body, this expands and presses against the inner wall of the pot of the first metal body such that the free end of the first metal body moves and thereby releases the connection to the second metal body. In this way, the thermal contact between the first and the second metal body can be opened. Upon cooling of the first metal body of the first metal body enclosing formed as a ring third metal body contracts and presses the free end of the first metal body against the second metal body. In this way, the thermal switch can be closed.

task The present invention is to provide a refrigeration system in which the ones to be cooled Parts of a device with a heat pipe in which a liquid can be circulated after a thermosyphon effect, with a heat sink are connected, with the to be cooled Parts of a device without a mechanical separation largely thermally from the heat sink should be decoupled.

This object is achieved with the measures specified in claim 1. The present The invention is based on the following considerations: The heat exchange between the heat sink and the parts of a device to be cooled takes place essentially by the liquid which can be circulated in the heat pipe according to a thermosiphon effect. For thermal separation of the heat sink from the parts to be cooled of the device, the heat pipe can be pumped off via a pipe connected to its interior. The heat pipe should be made of a poor thermal conductivity material at the same time. By these measures, the thermal connection between the heat sink and the parts to be cooled of the device is reduced to a defined by the solid state heat conductivity of the heat pipe low level. According to the invention, the refrigeration system should contain at least one hot connection element, which is thermally connected to parts of a device to be cooled, and a cold connection element, which is thermally connected to a heat sink containing. A heat pipe made of poorly heat-conducting material should be connected at a first end to the hot connection element and at a second end to be mechanically detachable with the cold connection element. The interior of the heat pipe should be at least partially filled with a liquid which can be circulated according to a thermosiphon effect. Furthermore, the refrigeration system should comprise a pipeline which is connected with a first end to the interior of the heat pipe and is configured such that at least parts of the pipeline are geodetically higher than the liquid level. For the thermal separation of the connecting elements according to the invention, the liquid should be able to be pumped out of the heat pipe via the pipeline.

The Advantages of a refrigeration system with the aforementioned features are mainly seen in that a heat transfer over the Heat pipe clearly is lowered by the liquid from the inside of the heat pipe is pumped out. In this way, the to be cooled Parts of a device thermally largely decoupled from the heat sink be without a second heat sink needed is moved and without one or more heat sinks mechanically Need to become. Is the heat sink, which is mechanically removable connected to the cold connection element, from the refrigeration system removed, the cold connection element can within a short Time to warm up, that in particular air or other contained in the ambient atmosphere Gases only to a small extent the surface Freeze the cold connector. Ice formation at the contact surfaces between the cold connection element and the heat sink can in this way largely be avoided. Due to the reduced ice formation is the thermal contact when reinserting the heat sink significantly better as in the case where there is significant ice formation at the contact surfaces. Furthermore, the cryogenic area remains in which the to be cooled Parts of the device are due to the thermal decoupling prevented from penetrating into this area heat flows. In this way stay with an exchange of the heat sink to be cooled Parts of a facility at the desired low temperature. With the aforementioned measures can a refrigeration system which allows it, even when used a single heat sink, without a warming the one to be cooled Parts becomes necessary, the heat sink replace or wait or temporarily remove. The refrigeration system according to the invention is especially for Devices in the field of superconductivity suitable.

• – Die zu kühlenden Teile der Einrichtung können in einem evakuierbaren Kryostaten angeordnet sein und das zweite Ende der Rohrleitung kann außerhalb des Kryostaten liegen. Tiefkalte Teile einer Einrichtung können besonders vorteilhaft mittels eines evakuierbaren Kryostaten thermisch vor ihrer Umgebung isoliert werden. Eine solche thermische Isolation stellt eine besonders effektive Isolation für tiefkalte Teile einer Einrichtung dar. Insbesondere bei solchen tiefkalten Teilen einer Einrichtung ist es wünschenswert, eine Eisbildung an den Kontaktflächen des kalten Verbindungselementes zu vermeiden. Der Einsatz einer Kälteanlage gemäß dem vorstehenden Ausführungsbeispiel ist daher insbesondere für Vorrichtungen mit tiefkalten Teilen besonders vorteilhaft.
• – Es kann eine mehrstufige Kältemaschine mit einer ersten und einer zweiten Stufe vorhanden sein, wobei die Wärmesenke von der zweiten Stufe gebildet sein kann und die erste Stufe mechanisch lösbar mit einem innerhalb des Kryostaten angeordneten Wärmeschild verbunden sein kann. Eine mehrstufige Kältemaschine ist besonders für tiefkalt zu kühlende Teile einer Einrichtung geeignet. Besonders vorteilhaft ist es, einen Wärmeschild als eine weitere Maßnahme zur thermischen Isolation einzusetzen. Die erfindungsgemäße thermische Trennung der zu kühlenden Teile einer Einrichtung von der zweiten Stufe der Kältemaschine ist besonders vorteilhaft, da insbesondere bei mechanisch komplexen Kühlsystemen der Vorteil einer thermischen Trennung ohne bewegliche Teile zum Tragen kommt.
• – Zumindest Teile der Kältemaschine können in einem von dem evakuierbaren Kryostaten abgetrennten, evakuierbaren Wartungsraum auswechselbar angebracht sein. Mit Hilfe eines weiteren, von dem evakuierbaren Kryostaten abgetrennten, ebenfalls evakuierbaren Wartungsraums kann der Auswechselvorgang der Kältemaschine vorgenommen werden, ohne dass das Vakuum des Kryostaten gebrochen werden muss. Der Wartungsvorgang gestaltet sich in dieser Weise besonders einfach und effektiv.
• – Die Flüssigkeit kann als ein Zweiphasengemisch vorliegen. Liegt die Flüssigkeit in dem Wärmerohr in zwei Phasen vor, so kann sich eine Zirkulation der Flüssigkeit in dem Wärmerohr einstellen, durch die gasförmige Flüssigkeit an dem kalten Ende des Wärmerohres kondensiert und flüssige Flüssigkeit an dem warmen Ende des Wärmerohres verdampft. Auf diese Weise kann die latente Wärme des Phasenübergangs zum Wärmetransport genutzt werden. Eine entsprechende Zirkulation kann sich aber auch in einer einphasigen Flüssigkeit auf Grund natürlicher, auf Dichteunterschieden basierender Konvektion einstellen.
• – Die Kälteanlage kann um eine Achse drehbar sein, welche im Wesentlichen parallel zu einer Symmetrieachse des Wärmerohres verläuft. Das Wärmerohr kann weiterhin in einem ersten Bereich, der mit dem warmen Verbindungselement verbunden ist, einen größeren Querschnitt aufweisen als in einem zweiten Bereich, der mit dem kalten Verbindungselement verbunden ist. Die Teile des Wärmerohres, die den ersten und den zweiten Bereich miteinander verbinden, können derart ausgestaltet sein, dass in dem zweiten Bereich kondensiertes Kältemittel ungehindert unter dem Einfluss der Schwerkraft zu dem ersten Bereich gelangen kann. Eine Kälteanlage mit den zuvor genannten Merkmalen kann insbesondere vorteilhaft für bewegliche, in diesem Fall drehbar angeordnete zu kühlende Teile einer Einrichtung verwendet werden. Durch die spezielle Ausgestaltung des Wärmerohres wird auch bei einer Drehung der zu kühlenden Teile einer Einrichtung jederzeit der thermische Kontakt zwischen der Kältemaschine und den zu kühlenden Teilen der Einrichtung gewährleistet.
• – Die Rohrleitung kann an ihren Enden nahe der Symmetrieachse des Wärmerohres mit dem Wärmerohr und der Außenseite des Kryostaten verbunden sein. Die Rohrleitung kann weiterhin in Verlaufsrichtung mindestens einen der Achse nahen Zwischenbereich aufweisen. Durch eine Ausgestaltung der Rohrleitung, wie sie zuvor beschrieben ist, kann bei einer Drehung der zu kühlenden Teile einer Einrichtung verhindert werden, das Kältemittel durch die Rohrleitung bis an das warme Ende der Rohrleitung vordringt, welches außerhalb des Kryostaten befestigt ist. Auf diese Weise wird vermieden, dass sich eine Zirkulation des Kältemittels in der Rohrleitung zwischen dem innerhalb des Wärmerohres befindlichen tiefkalten Bereich und dem Ende der Rohrleitung, welches außerhalb des Kryostaten angebracht ist, stattfindet. Besonders vorteilhaft kann durch die zuvor beschriebene Ausgestaltung der Rohrleitung Wärmeverluste durch eine wie zuvor beschriebene Zirkulation des Kältemittels unterbunden werden.
• – Der Zwischenbereich der Rohrleitung kann einen V-förmigen Verlauf in Richtung der Achse A aufweisen. Eine V-förmig gebogene Rohrleitung stellt eine besonders einfache und effektive Ausgestaltungsform der Rohrleitung dar.
• – Das Wärmerohr kann im Wesentlichen in der Form eines Kegelstumpfes ausgestaltet sein. Durch eine Ausbildung des Wärmerohres in der Form eines Kegelstumpfes kann eine besonders einfache kostengünstige und effektive Form des Wärmerohrs angegeben werden.
• – Die Kälteanlage kann ein Zusatzkühlsystem umfassen, welches zumindest die folgenden Merkmale aufweist: Einen Kältemittelraum, welcher mit dem kalten Verbindungselement verbunden ist; eine Zuleitung, durch welche der Kältemit telraum von einem geodätisch höher gelegenen Ort außerhalb des Kryostaten mit einem zweiten Kältemittel befüllbar ist; ein Rohrleitungssystem, welches thermisch großflächig mit den zu kühlenden Teilen der Einrichtung verbunden ist und in welchen das zweite Kältemittel bedingt durch einen Thermosiphoneffekt zirkulierbar ist; eine Abgasleitung, durch welche gasförmiges zweites Kältemittel aus dem Rohrleitungssystem entweichen kann. Durch ein Zusatzkühlsystem mit den zuvor genannten Merkmalen kann insbesondere bei großen zu kühlenden Massen eine Beschleunigung der Abkühlphase erreicht werden. Indem über die Zuleitung ein zweites Kältemittel von einem geodätisch höher gelegenen Ort außerhalb des Kryostaten in den Kältemittelraum gefüllt wird, wird zusätzliche Kühlleistung für die zu kühlenden Teile einer Einrichtung bereitgestellt. Gegebenenfalls abdampfendes zweites Kältemittel kann über die Abgasleitung aus dem Rohrleitungssystem entweichen. Auf diese Weise wird die Bildung eines Überdruckes in dem Rohrleitungssystem verhindert. Innerhalb des Rohrleitungssystems kann das zweite Kältemittel nach einem Thermosiphoneffekt zirkulieren und so für eine effektive Kühlung sorgen.
• – Die Verbindungselemente können aus einem gut wärmeleitfähigen Material, vorzugsweise aus Kupfer, bestehen. Das Wärmerohr kann aus einem Material mit einer thermischen Leitfähigkeit geringer als der von Kupfer, vorzugsweise aus Edelstahl, bestehen. Durch eine derartige Ausgestaltung der Verbindungselemente aus einem gut wärmeleitfähigen Material wie z.B. Kupfer, kann eine besondere effektive thermische Ankopplung sowohl an die Wärmesenke wie auch an die zu kühlenden Teile der Einrichtung erreicht werden. Die Wärmeleitfähigkeit des Wärmerohres ist vor allem durch das innerhalb des Wärmerohrs zirkulierende Kältemittel bedingt. Wird das Wärmerohr selbst aus einem schlecht wärmeleitfähigen Material wie z.B. Edelstahl hergestellt, so kann durch Abpumpen des Kältemittels eine besonders starke Reduzierung der Wärmeleitfähigkeit erreicht werden.
• – Die Einrichtung kann eine Gantry-Vorrichtung zur Strahlentherapie sein, und die zu kühlenden Teile können die Magnete der Gantry zur Ablenkung eines Teilchenstrahls sein. Die erfindungsgemäße Kälteanlage ist für eine Gantry besonders geeignet, da die zu kühlenden Magnete um eine Rotationsachse der Gantry gedreht werden.

Advantageous embodiments of the refrigeration system according to the invention will become apparent from the dependent of claim 1 claims. In this case, the embodiment can be combined according to claim 1 with the features of one of the subclaims or preferably also those of several subclaims. Accordingly, the refrigeration system according to the invention may additionally have the following features:

• The parts of the device to be cooled can be arranged in an evacuatable cryostat and the second end of the pipeline can be outside the cryostat. Deep-frozen parts of a device can be thermally insulated from their environment particularly advantageously by means of an evacuatable cryostat. Such a thermal insulation is a particularly effective insulation for cryogenic parts of a device. Especially in such cryogenic parts of a device, it is desirable to avoid ice formation on the contact surfaces of the cold connection element. The use of a refrigeration system according to the above embodiment is therefore particularly advantageous especially for devices with cryogenic parts.
• - There may be a multi-stage refrigerator with a first and a second stage, wherein the heat sink may be formed by the second stage and the first stage may be mechanically detachably connected to a disposed within the cryostat heat shield. A multi-stage chiller is particularly suitable for cryogenic parts of a device to be cooled. It is particularly advantageous to use a heat shield as a further measure for thermal insulation. The thermal separation according to the invention of the parts to be cooled of a device from the second stage of the refrigerating machine is particularly advantageous, since the advantage of a thermal separation without moving parts comes into play particularly in mechanically complex cooling systems.
• - At least parts of the refrigerator can be separated in one of the evacuated cryostat ten, evacuable maintenance space be exchangeable attached. With the help of another, separated from the evacuated cryostat, also evacuated maintenance space of the replacement of the chiller can be made without the vacuum of the cryostat must be broken. The maintenance process is particularly simple and effective in this way.
• - The liquid can be present as a two-phase mixture. When the liquid in the heat pipe is in two phases, circulation of the liquid in the heat pipe can be established, condensing gaseous liquid at the cold end of the heat pipe, and vaporizing liquid liquid at the warm end of the heat pipe. In this way, the latent heat of the phase transition can be used for heat transport. However, a corresponding circulation can also be achieved in a single-phase liquid due to natural convection based on density differences.
• - The refrigeration system may be rotatable about an axis which is substantially parallel to an axis of symmetry of the heat pipe. The heat pipe can furthermore have a larger cross-section in a first region, which is connected to the warm connection element, than in a second region, which is connected to the cold connection element. The parts of the heat pipe connecting the first and the second area may be configured such that condensed refrigerant can freely move to the first area under the influence of gravity in the second area. A refrigeration system with the aforementioned features can be used in particular advantageous for movable, in this case rotatably arranged to be cooled parts of a device. Due to the special design of the heat pipe, the thermal contact between the chiller and the parts to be cooled of the device is ensured at any time with a rotation of the parts to be cooled of a device.
• - The pipe can be connected at their ends near the axis of symmetry of the heat pipe to the heat pipe and the outside of the cryostat. The pipeline may furthermore have at least one intermediate region near the axis in the direction of progression. By means of an embodiment of the pipeline as described above, upon rotation of the parts to be cooled, a device can be prevented which advances refrigerant through the pipeline to the warm end of the pipeline, which is fastened outside the cryostat. In this way it is avoided that a circulation of the refrigerant in the pipeline takes place between the deep-cold area located inside the heat pipe and the end of the pipe which is arranged outside the cryostat. Particularly advantageous can be prevented by a circulation of the refrigerant as described above by the above-described embodiment of the pipeline heat losses.
• The intermediate region of the pipeline can have a V-shaped course in the direction of the axis A. A V-shaped bent pipe represents a particularly simple and effective embodiment of the pipeline.
• - The heat pipe can be configured substantially in the shape of a truncated cone. By forming the heat pipe in the form of a truncated cone, a particularly simple inexpensive and effective form of the heat pipe can be specified.
• - The refrigeration system may include an additional cooling system having at least the following features: a refrigerant space which is connected to the cold connection element; a supply line through which the Kältemit telraum can be filled from a geodetically higher location outside of the cryostat with a second refrigerant; a piping system which is thermally connected over a large area with the parts to be cooled of the device and in which the second refrigerant is conditionally circulated by a thermosiphon effect; an exhaust pipe through which gaseous second refrigerant can escape from the piping system. By means of an additional cooling system with the aforementioned features, an acceleration of the cooling phase can be achieved, in particular for large masses to be cooled. By filling a second refrigerant from a geodetically elevated location outside the cryostat into the refrigerant space via the supply line, additional cooling capacity is provided for the parts of a device to be cooled. Optionally, evaporating second refrigerant can escape via the exhaust pipe from the piping system. In this way, the formation of an overpressure in the piping system is prevented. Within the piping system, the second refrigerant can circulate after a thermosiphon effect, thus providing effective cooling.
• - The connecting elements may be made of a good thermal conductivity material, preferably made of copper. The heat pipe may be made of a material having a thermal conductivity less than that of copper, preferably of stainless steel. Such a design of the connecting elements made of a good thermal conductivity material such as copper, a special effective thermal coupling can be achieved both to the heat sink as well as to the parts to be cooled of the device. The heat conductivity of the heat pipe is mainly due to the circulating within the heat pipe refrigerant. If the heat pipe itself is made of a poor thermal conductivity material such as stainless steel, so by pumping off the refrigerant, a particularly strong reduction of the thermal conductivity can be achieved.
• - The device can be a gantry device for Radiation therapy, and the parts to be cooled may be the magnets of the gantry for deflecting a particle beam. The refrigeration system according to the invention is particularly suitable for a gantry, since the magnets to be cooled are rotated about an axis of rotation of the gantry.

Further advantageous embodiments of the refrigeration system according to the invention will be apparent from the above not addressed claims and in particular from the following explanatory drawing. In the drawing, preferred embodiments of the refrigeration system according to the invention indicated in slightly schematized form. This show their

1 the cross-section of a refrigeration system,

2 the cross section of a rotatable refrigeration system and

3 the cross section of a rotatable refrigeration system with an additional cooling system.

Yourself in the figures corresponding parts are each given the same reference numerals Mistake. Not closer executed Parts are generally state of the art.

1 shows the schematic structure of a refrigeration system 100 according to an embodiment. In a cryostat 108 are the parts to be cooled 102 a facility. The parts to be cooled 102 The device may be, for example, the magnet windings of a superconducting magnet or other parts of the superconducting technique. Inside the cryostat 108 is a heat shield to improve thermal insulation 112 appropriate. The cooling capacity for the parts to be cooled 102 The device is powered by a chiller 109 , eg a cold head or a Stirling cooler, provided. Preferably, a cold head can be used, which operates on the Gifford-McMahon principle. Such a two-stage refrigerator can according to the present embodiment with its first stage 111 thermally with the heat shield 112 be connected. The connection between the first stage 111 the chiller 109 and the heat shield 112 may preferably be a releasable mechanical connection, such as a screw or clamp connection, which simultaneously ensures good thermal contact of the components. The second stage 110 the chiller 109 represents the actual heat sink 104 the refrigeration system 100 dar. The second stage 110 the chiller 109 is thermal with a cold connection element 103 connected. The corresponding connection may preferably be a screw connection. That is, the chiller 109 comes with her second stage 110 in the cold connection element 103 detachably screwed. Any other mechanical connection which is releasable and at the same time good thermal contact between the second stage 110 the chiller 109 and the cold connection element 103 is also guaranteed for the in 1 illustrated embodiment suitable. The connecting elements 101 and 103 can be a part of the parts to be cooled 102 a device or the heat sink 104 be. They can continue to be integrated into the corresponding components or permanently connected to them.

The chiller 109 is partly located in a separately evacuated maintenance room 113 , This maintenance room 113 is from the rest of the evacuable space of the cryostat 108 separated. The cold connection element 103 is with a heat pipe 105 good thermal conductivity and preferably also mechanically connected. On the opposite side is the heat pipe 105 with a warm connection element 101 connected. This compound is also designed to conduct heat well and may preferably also be a mechanical connection. The warm connection element 101 is again good heat-conducting with the parts to be cooled 102 connected to a facility. Inside the heat pipe 105 there is a liquid 106 which are in the heat pipe 105 can circulate according to a thermosiphon effect. The heat pipe 105 itself, however, consists of a poorly heat-conducting material.

Is the heat pipe 105 completely filled with the liquid, this may be in the upper cold area of the heat pipe 105 , due to temperature, assume a higher density than in the lower, warmer area of the heat pipe 105 , Due to the density differences of the liquid 106 can be in the heat pipe 105 Set a circulation according to the so-called. Thermosiphon effect, which heat transport from the parts to be cooled 102 the device to the heat sink 104 causes.

Furthermore, the heat pipe 105 only partially with a liquid 106 be filled. In this case, there may be a circulation of the liquid 106 set in two different phases, eg liquid-gaseous. Accordingly, gaseous liquid becomes in the part of the heat pipe 105 , which is in thermal contact with the cold connector 103 is liquefied. Condensed liquid 106 moves gravity-driven into the in 1 part of the heat pipe shown below 105 , which is in thermal contact with the hot connector 101 located. In this part of the heat pipe 105 gives the liquid 106 the cooling capacity to the warm connector 101 from (and thus also to the parts of the device to be cooled 102 ), whereupon gaseous liquid 106 again in the upper part of the heat pipe rises. In this case, the cold connector acts 103 as a condenser and the warm connector as an evaporator. In this way, a good thermal connection between the chiller 109 or its second stage 110 and the parts to be cooled 102 a facility.

During operation of a refrigeration system 100 There may be a need for a chiller 109 eg for maintenance or due to a defect must be replaced. Before the chiller 109 from the refrigeration system 100 is removed, the liquid becomes 106 which are inside the heat pipe 105 located, via a pipe leading to the outside 107 pumped out. It is sufficient in many cases, the liquid 106 for the most part from the heat pipe 105 pump out; but it can also be completely removed from the heat pipe 105 be removed. By the liquid 106 from the heat pipe 105 is removed, the thermal conductivity of the heat merohres 105 considerably reduced. Between the cold connection element 103 and the warm connection element 101 will find below a heat conduction only as a result of solid-state heat conduction through the material of the heat pipe 105 instead of. Will the heat pipe 105 Made of a poor thermal conductivity material such as stainless steel, the thermal conduction between the fasteners 101 . 103 be reduced to a minimum. As materials for the heat pipe 105 In addition to stainless steel, various plastics, ceramics or other low-temperature suitable materials can be used. Another measure to minimize heat conduction is the heat pipe 105 To produce particularly thin-walled and / or with small geometric dimensions.

After the liquid 106 from the heat pipe 105 over the pipeline 107 can be pumped out, the maintenance room 113 be ventilated. Due to the in the maintenance room 113 incoming ambient air begins the cold connection element 103 as well as the previously cold parts of the chiller 109 to warm up. The maintenance room 113 can also be flooded with a special purge gas, such as dried air, nitrogen or helium. After the maintenance room 113 has been vented, the chiller can 109 from the refrigeration system 100 be removed. The formerly deep cold connection element 103 is of the remaining still cryogenic parts, especially the warm connection element 101 and the parts to be cooled 102 a device that is thermally decoupled and will therefore quickly warm to a temperature near room temperature. Because the cold connection element 103 heated as described above, ice formation by condensing gas, preferably ambient air, is largely avoided. When replacing the chiller 109 is therefore a good thermal and mechanical contact between the second stage 110 and the cold connection element 103 guaranteed.

superconducting Magnetic windings are particularly suitable for irradiation systems, as used in particle therapy, e.g. used for the fight against cancer become. Such superconducting magnet windings are preferred mounted in a so-called gantry, which is a fixed one Axis is rotatable.

2 shows a further embodiment of the generally with 100 designated refrigeration system, the entire refrigeration system 100 including the parts to be cooled 102 are arranged rotatably about an axis A. According to the in 2 illustrated embodiment of the refrigeration system 100 are the parts to be cooled 102 in a cryostat 108 , which in addition a heat shield 112 having. The chiller 109 is preferably designed with respect to a further axis B rotationally symmetrical. The chiller 109 is in a maintenance room 113 housed, which separated from the cryostat 108 is evacuable. The first stage 111 the chiller 109 is with the heat shield 112 connected, the second stage 104 the chiller 109 is with the cold connection element 103 connected. The heat pipe 105 is located with a first part 202 in thermal, preferably also mechanical connection with the cold connection element 103 , Another part 201 of the heat pipe 105 is in thermal, preferably also mechanical contact with the warm connection element 101 , The first part 202 of the heat pipe 105 has a smaller cross section than the second part 201 of the heat pipe 105 on. The part 203 of the heat pipe 105 which is the first part 202 and the second part 201 of the heat pipe 105 connects, is designed such that through this part 203 condensed liquid 106 due to gravity freely from the first area 202 in the second area 201 can get. The entire heat pipe 105 may preferably have the shape of a truncated cone closed on both sides. Such a heat pipe 105 can continue with the chiller 109 be connected, that the axis of symmetry of the truncated cone coincides with the axis B.

In the area of this axis B is a pipeline 107 with the heat pipe 105 connected. Through this pipeline is the liquid 106 from the heat pipe 105 pumped out. The pipeline 107 has such a shape that any of the heat pipe 105 into the pipeline 107 entering liquid 106 not unhindered to the outside, in conjunction with the cryostat 108 standing part the pipeline 107 can get. For this purpose, the pipeline points 107 a bent in the direction of the axis A part 204 on. By such a configuration of the tube 107 can even with a rotation of the entire refrigeration system 100 around the axis A prevents that liquid 106 through the pipeline 107 in constant contact with the outer part of the pipeline 107 occurs.

As related to 1 described, the liquid can 106 from the heat pipe 105 through the pipeline 107 be pumped out. In this way, a thermal separation between the parts to be cooled 102 a device and the heat sink 104 reached. Even with such a rotatable about an axis A refrigeration system 100 the chiller 109 For example, to be able to replace maintenance, after pumping the liquid 106 the workroom 113 ventilated. In the event that the heat shield 112 a rigid connection with the cryostat 108 can, the parts of the work space 113 between the mounting flange of the first stage 111 the chiller with the heat shield 112 and the capacitor 103 are arranged flexibly configured. Such a flexible configuration can be done for example by means of a bellows. To a separation between the second stage 110 the chiller 109 and the capacitor 103 to allow the capacitor can 103 due to a flexible design of the heat pipe 105 be movable along the axis B. The heat pipe 105 may also have a bellows for this purpose.

3 shows a further embodiment of a generally with 100 designated refrigeration system. In the 3 Darge presented refrigeration system 100 is opposite to those in 2 shown is extended to an additional cooling system. A refrigerant room 301 is in thermal, preferably also mechanical contact with the cold connection element 103 , This refrigerant space 301 is through a supply line 302 from a geodetically higher place fillable. As a refrigerant, the same or similar refrigerant can be used as it is for the heat pipe 105 is used. Usable are, for example, helium, neon or nitrogen. To the refrigerant space 301 is a piping system 303 connected, which has a large area with the parts to be cooled 102 a device is connected. In this way, additional cooling capacity to the parts to be cooled 102 to be brought to a facility. In this way, the cooling times, for example, for a superconducting magnet can be significantly reduced. Optionally in the piping system 303 vaporizing refrigerant can be via an exhaust pipe 304 from the piping system 303 escape. In this way, an overpressure in the piping system 303 avoided.

The additional cooling device can be used, for example, such that the parts to be cooled 102 a device first with nitrogen, which is inexpensive and readily available, are pre-cooled before using the chiller 109 the parts to be cooled 102 be cooled to even lower temperatures. For the use of additional cooling device, it is technically necessary, the refrigeration system 100 to stop in their possible rotation about the axis A or at least to move so slowly that in the pipeline system 303 a gravity-driven refrigerant circuit, which is based on a thermosiphon effect set.

Claims (15)

Refrigeration system ( 100 ) with at least a. a warm connection element ( 101 ), which with parts to be cooled ( 102 ) is thermally connected to a device, b. a cold connection element ( 103 ), which thermally with a heat sink ( 104 ), c. a heat pipe ( 105 ) made of poorly heat-conducting material, which at a first end with the warm connecting element ( 101 ) and at a second end mechanically releasable with the cold connection element ( 103 ) and the interior of which is at least partially connected to a liquid which can be circulated according to a thermosiphon effect ( 106 ) is filled, and d. a pipeline ( 107 ), which at a first end with the interior of the heat pipe ( 105 ) and is configured such that at least parts of the pipeline ( 107 Geodetic higher than the liquid level, e. wherein a thermal separation of the connecting elements ( 101 . 103 ) the liquid ( 106 ) over the pipeline ( 107 ) is pumpable. Refrigeration system ( 100 ) according to claim 1, characterized in that the parts to be cooled ( 102 ) of the device in an evacuable cryostat ( 108 ) and the second end of the pipeline ( 107 ) outside the cryostat ( 108 ) lies. Refrigeration system ( 100 ) according to claim 2, characterized in that a multi-stage refrigerator ( 109 ) with a first stage ( 111 ) and a second stage ( 110 ) is present, wherein the heat sink ( 104 ) of the second stage ( 110 ), and the first stage ( 111 ) mechanically releasable with a within the cryostat ( 108 ) arranged heat shield ( 112 ) connected is. Refrigeration system ( 100 ) according to claim 3, characterized in that at least parts of the refrigerating machine ( 109 ) in one of the evacuable cryos did ( 108 ) separated, evacuable maintenance room ( 113 ) are mounted interchangeably. Refrigeration system ( 100 ) according to one of the preceding claims, characterized in that the liquid ( 106 ) is present as a two phase mixture. Refrigeration system ( 100 ) according to one of the preceding claims, characterized in that a. a rotation about an axis (A) is provided, which is substantially parallel to an axis of symmetry (B) of the heat pipe ( 105 ), and b. the heat pipe ( 105 ) in a first area ( 201 ), which with the warm connection element ( 101 ) has a larger cross section than in a second area ( 202 ) connected to the cold connection element ( 103 ), and the parts ( 203 ) of the heat pipe, the first ( 201 ) and the second area ( 202 ) are connected to each other, are configured such that in the second area ( 202 ) condensed refrigerant ( 106 ) freely under the influence of gravity in the first area ( 201 ) can get. Refrigeration system according to claim 6, characterized in that the pipeline ( 107 ) at their ends near the axis of symmetry (B) of the heat pipe ( 105 ) with the heat pipe ( 105 ) and the outside of the cryostat ( 108 ), and the pipeline ( 107 ) in the direction of at least one of the axis (A) near intermediate region ( 204 ) having. Refrigeration system according to claim 7, characterized in that the intermediate region ( 204 ) in the direction of the pipeline ( 107 ) has a V-shaped bend in the direction of the axis (A). Cooling system according to one of claims 6 to 8, characterized in that the heat pipe ( 105 ) is formed substantially in the shape of a truncated cone. Refrigeration system according to one of the preceding claims, characterized by an additional cooling system, comprising a. one with the cold connection element ( 103 ) connected refrigerant space ( 301 b. a supply line ( 302 ), through which the refrigerant space ( 301 ) from a geodetically higher location outside the cryostat ( 108 ) can be filled with a second refrigerant, c. a pipeline system ( 303 ), which thermally large area with the parts to be cooled ( 102 ) is connected to the device and in which the second refrigerant is circulated due to a thermosiphon effect, and d. an exhaust pipe ( 304 ), through which gaseous second refrigerant from the piping system ( 303 ) can escape. Refrigeration system according to one of the preceding claims, characterized in that the connecting elements ( 101 . 103 ) consist of a good thermal conductivity material, preferably of copper. Refrigeration system according to one of the preceding claims, characterized in that the heat pipe ( 105 ) is made of a material having a thermal conductivity lower than that of copper, preferably made of stainless steel. refrigeration plant according to one of the preceding claims, characterized in that the device superconducting parts contains. refrigeration plant according to one of the preceding claims, characterized in that the device is a gantry device for radiotherapy is. Refrigeration system according to claim 14, characterized in that the parts to be cooled ( 102 ) Magnets, preferably superconducting magnets, for deflecting a particle beam.