Abstract: A method for autonomously cooling down a cryogen-free superconductive magnetic coil system includes: (a1) measuring the current temperature Tactual at the magnet and comparing it to a temperature target value T1target; (a2) if Tactual>T1target, actuating a vacuum pump and opening a barrier valve in a vacuum conduit that leads from the vacuum pump into a vacuum vessel containing the magnet; (b1) measuring the current pressure Pactual in the vacuum vessel and comparing it to a pressure target value P1target; (b2) if Pactual<P1target, activating a cold head for cooling a cooling arm; (c1) measuring Tactual and comparing it to the first temperature target value T1target; (c2) if Tactual<T1target, closing the barrier valve and switching off the vacuum pump; (d1) measuring Tactual and comparing it to a second temperature target value T2target and maintaining the second temperature target value T2target.

Abstract: A cryostat assembly with an outer container for a storage tank with a first cryogenic fluid and a coil tank for a superconducting magnet coil system. The magnet coil system is cooled by a second cryogenic fluid colder than the first cryogenic fluid, the coil tank being mechanically connected to the outer container and/or to radiation shields surrounding the coil tank via a mounting structure. Liquid helium at an operating temperature of approximately 4.2 K is the first cryogenic, fluid and helium at an operating temperature of <3.5 K is the second cryogenic fluid in the coil tank. The mounting structure has mounting elements with thermally conductive contact points thermally coupled to heat sinks having a temperature at or below that of the storage tank, via thermal conductor elements. This ensures long times to quench if malfunctions occur.

Abstract: A magnet assembly (1) with a cryostat (2) has a superconducting magnet coil system (3), an active cooling device (4) for the coil system, and current leads (5a, 5b) for charging the coil system. The current leads have at least one normal-conducting region (15a, 15b), wherein multiple cold reservoirs (20) are thermally coupled to the current leads along the normal-conducting region thereof, in order to absorb heat the normal-conducting region during charging of the magnet coil system. The current leads have a variable cross-sectional area B in the normal-conducting region along the extension direction thereof, wherein at least over a predominant fraction of their overall length in the normal-conducting region, the cross-sectional area B decreases from a cold end (18a, 18b) toward a warm end (19a, 19b). This provides a magnet assembly requiring reduced cooling power during charging, with less heat introduced into the magnet coil system in normal operation.

Abstract: A cryostat assembly with an outer container for a storage tank (3) with a first cryogenic fluid and a coil tank (4) for a superconducting magnet coil system (5). The magnet coil system is cooled by a second cryogenic fluid colder than the first cryogenic fluid, the coil tank being mechanically connected to the outer container and/or to radiation shields (6) surrounding the coil tank via a mounting structure. Liquid helium at an operating temperature of approximately 4.2 K is the first cryogenic fluid and helium at an operating temperature of <3.5 K is the second cryogenic fluid in the coil tank. The mounting structure has mounting elements (7) with thermally conductive contact points (7a) thermally coupled to heat sinks having a temperature at or below that of the storage tank, via thermal conductor elements (8). This ensures long times to quench if malfunctions occur.

Abstract: A cryostat arrangement (1?) having a vacuum container (2) and an object (4) to be cooled, which is arranged inside the vacuum container. A neck tube (8) leads to the object, and a cooling arm (10) of a cold head (11), around which a closed cavity (9) is formed, is arranged in the neck tube, which is sealed off fluid-tight in relation to the object and is filled with cryogenic fluid in normal operation. A thermal coupling element (15) couples the cryogenic fluid in the cavity to the object. A pump device (14), to which the cavity is connected via a valve (13) and with which the cavity is pumped out if the cold head fails. A monitoring unit (17) monitors the cooling function of the cold head, and activates the pump device to pump out the cavity if the cooling function of the cold head drops.

Abstract: A magnet assembly (1) with a cryostat (2) has a superconducting magnet coil system (3), an active cooling device (4) for the coil system, and current leads (5a, 5b) for charging the coil system. The current leads have at least one normal-conducting region (15a, 15b), wherein multiple cold reservoirs (20) are thermally coupled to the current leads along the normal-conducting region thereof, in order to absorb heat the normal-conducting region during charging of the magnet coil system. The current leads have a variable cross-sectional area B in the normal-conducting region along the extension direction thereof, wherein at least over a predominant fraction of their overall length in the normal-conducting region, the cross-sectional area B decreases from a cold end (18a, 18b) toward a warm end (19a, 19b). This provides a magnet assembly requiring reduced cooling power during charging, with less heat introduced into the magnet coil system in normal operation.

Abstract: A method is provided for precooling a cryostat having a hollow cold head turret into which a neck tube protrudes and connects an object to be cooled to the exterior of the cryostat, wherein a cold head having a cold head stage for cooling a cryogenic working medium may be introduced into the neck tube. During a condensation operation the cryogenic working medium flows through a heat pipe into an evaporator chamber which is thermally conductively connected to the object to be cooled. During a precooling phase a precisely fitting, thermally conductive short circuit block is inserted through the neck tube into the heat pipe to provide thermal conduction between the object to be cooled and a cooling device. The short circuit block is removed from the heat pipe after the target temperature is reached, and heat is subsequently transmitted through the heat pipe during a condensation operation.

Abstract: A method is provided for precooling a cryostat having a hollow cold head turret into which a neck tube protrudes and connects an object to be cooled to the exterior of the cryostat, wherein a cold head having a cold head stage for cooling a cryogenic working medium may be introduced into the neck tube. During a condensation operation the cryogenic working medium flows through a heat pipe into an evaporator chamber which is thermally conductively connected to the object to be cooled. During a precooling phase a precisely fitting, thermally conductive short circuit block is inserted through the neck tube into the heat pipe to provide thermal conduction between the object to be cooled and a cooling device The short circuit block is removed from the heat pipe after the target temperature is reached, and heat is subsequently transmitted through the heat pipe during a condensation operation.

Abstract: A cryostat has a cooling arm with a first thermal contact surface which can be brought into thermal contact with a second thermal contact surface on an object to be cooled. A hollow volume (2) between the inner side of the neck tube, the cooling arm, and the object is filled with gas and the cooling arm is pressurized by the inner pressure of the gas and also by atmospheric pressure. A contact device brings the first and the second contact surfaces into thermal contact below a threshold gas pressure and moves them away from each other when the threshold pressure has been exceeded such that a gap (13) filled with gas thermally separates the first and second contact surfaces. Operationally safe and fully automatic reduction of the thermal load acting on the object to be cooled is thereby obtained in case the cooling machine fails.

Abstract: A cryostat for subcooled (<2.5 K) liquid helium includes two separate helium tanks. A Joule-Thomson cooling unit includes a heat exchanger in the lower part of the first helium tank and uses liquid stored in the second helium tank in order to cool the subcooled liquid helium stored in the lower part of the first helium tank. The Joule-Thomson cooling unit draws in liquid helium either directly from the second helium tank or from the first helium tank, which is replenished via the gas phase from the second helium tank. In this way, the subcooled liquid helium of the first helium tank can be cooled for a long time from a combined stock of liquid helium in the first helium tank and the second helium tank. The second helium tank may be arranged adjacent or surrounding the first helium tank to maintain a lower overall height of the cryostat.

Abstract: A method is provided for precooling a cryostat having a hollow cold head turret into which a neck tube protrudes and connects an object to be cooled to the exterior of the cryostat, wherein a cold head having a cold head stage for cooling a cryogenic working medium may be introduced into the neck tube. During a condensation operation the cryogenic working medium flows through a heat pipe into an evaporator chamber which is thermally conductively connected to the object to be cooled. During a precooling phase a precisely fitting, thermally conductive short circuit block is inserted through the neck tube into the heat pipe to provide thermal conduction between the object to be cooled and a cooling device The short circuit block is removed from the heat pipe after the target temperature is reached, and heat is subsequently transmitted through the heat pipe during a condensation operation.

Abstract: A cryostat has a cooling arm with a first thermal contact surface which can be brought into thermal contact with a second thermal contact surface on an object to be cooled. A hollow volume (2) between the inner side of the neck tube, the cooling arm, and the object is filled with gas and the cooling arm is pressurized by the inner pressure of the gas and also by atmospheric pressure. A contact device brings the first and the second contact surfaces into thermal contact below a threshold gas pressure and moves them away from each other when the threshold pressure has been exceeded such that a gap (13) filled with gas thermally separates the first and second contact surfaces. Operationally safe and fully automatic reduction of the thermal load acting on the object to be cooled is thereby obtained in case the cooling machine fails.

Abstract: A nuclear magnetic resonance (NMR) apparatus (10) comprises a superconducting main field magnet coil system (14) which generates a homogeneous magnetic field of at least 3T, and a gradient coil system (15) which generates a gradient strength of at least 10 mTm?1, with a slew rate of at least 100 Tm?1s?1, wherein the main field magnet coil system (14) is arranged in a cryostat (12) with liquid helium and a refrigerator (16) in the form of a pulse tube cooler or a Gifford-McMahon cooler, and wherein an evaporation line (17a, 27a, 37a) is provided for helium that might evaporate from the cryostat. In all states of operation of the NMR apparatus (10) without gradient switching, the refrigerator provides a cooling capacity which is at least 0.

Abstract: A method for cooling a cryostat configuration (1, 1?) during transport, wherein the cryostat configuration (1) comprises a superconducting magnet coil (2) in a helium tank (8) containing liquid helium (9), which is surrounded by at least one radiation shield (10), wherein the cooling inside the cryostat configuration (1, 1?) in stationary operation is performed entirely without liquid nitrogen by means of a refrigerator, characterized in that during transport, the refrigerator is switched off and instead, liquid nitrogen (6) is conducted from an external nitrogen vessel (4) via a supply tube (7) from the nitrogen vessel (4) to the cryostat configuration (1, 1?) and brought into thermal contact with the radiation shield (10) by means of a thermal contact element (11) in the cryostat configuration (1, 1?). In this way, the consumption of liquid helium during transport can be greatly reduced and the possible transport time of a charged superconducting magnet configuration increased.

Abstract: A nuclear magnetic resonance (NMR) apparatus (10) comprises a superconducting main field magnet coil system (14) which generates a homogeneous magnetic field of at least 3T, and a gradient coil system (15) which generates a gradient strength of at least 10 mTm?1, with a slew rate of at least 100 Tm?1s?1, wherein the main field magnet coil system (14) is arranged in a cryostat (12) with liquid helium and a refrigerator (16) in the form of a pulse tube cooler or a Gifford-McMahon cooler, and wherein an evaporation line (17a, 27a, 37a) is provided for helium that might evaporate from the cryostat. In all states of operation of the NMR apparatus (10) without gradient switching, the refrigerator provides a cooling capacity which is at least 0.

Abstract: A cryostat configuration (10), with at least one cryostat (11), which has at least one first chamber (1) with supercooled liquid helium having a temperature of less than 4 K and at least one further chamber (2), which contains liquid helium having a temperature of approximately 4.

Abstract: A cryostat configuration has a magnet coil system (2) disposed in a helium tank (1), and a horizontal room temperature bore (3) which provides access to a volume under investigation in the center of the magnet coil system (2). The helium tank (1) contains undercooled liquid helium at a temperature of less than 3.5 K, in particular of approximately 2 K, and the cryostat configuration has at least one vertical tower structure (4) on its upper side for filling in and evaporating helium. The tower structure (4) contains a container (5) with liquid helium of 4.2 K which is separated from the helium tank (1) by a thermal barrier (7), and the helium tank (1) contains an undercooling unit (9). This yields a compact cryostat configuration which achieves continuous, stable long-term operation with an undercooled high-field magnet coil.

Abstract: A method for cooling a cryostat configuration (1, 1?) during transport, wherein the cryostat configuration (1) comprises a superconducting magnet coil (2) in a helium tank (8) containing liquid helium (9), which is surrounded by at least one radiation shield (10), wherein the cooling inside the cryostat configuration (1, 1?) in stationary operation is performed entirely without liquid nitrogen by means of a refrigerator, characterized in that during transport, the refrigerator is switched off and instead, liquid nitrogen (6) is conducted from an external nitrogen vessel (4) via a supply tube (7) from the nitrogen vessel (4) to the cryostat configuration (1, 1?) and brought into thermal contact with the radiation shield (10) by means of a thermal contact element (11) in the cryostat configuration (1, 1?). In this way, the consumption of liquid helium during transport can be greatly reduced and the possible transport time of a charged superconducting magnet configuration increased.

Abstract: An NMR spectrometer comprising a magnet coil system disposed in the helium tank (8) of a cryostat and an NMR probe head (4) which is disposed in a room temperature bore of the cryostat and contains a cooled RF resonator (13) for receiving NMR signals from a sample to be examined, wherein the helium tank (8) and the NMR probe head (4) are cooled by a common, multi-stage, compressor-operated refrigerator, is characterized in that the common refrigerator comprises a cold head (6) and several heat exchangers (21, 24, 25, 28, 31, 33, 34) at different temperature levels, wherein the refrigerator is disposed at a spatial separation from the cryostat in a separate, evacuated and thermally insulated housing (5), and several cooling circuits (1a, 1b, 1c, 1d, 2a, 2b, 3a, 3b) having thermally insulated transfer lines (14a, 14b, 15) are provided between the housing (5) containing the heat exchangers (21, 24, 25, 28, 31, 33, 34) and the cryostat, and also between the housing (5) and the NMR probe head (4).

Abstract: An NMR apparatus comprising a superconducting magnet coil system, in particular, an NMR spectrometer, with a cryostat which comprises an outer shell and a helium tank which contains the magnet coil system, and with an NMR probe head which is disposed in a room temperature bore of the cryostat and which contains a cooled RF resonator for receiving NMR signals from a sample to be examined and is cooled, together with the NMR probe head, by a cold head of a common, multi-stage, compressor-operated refrigerator, is characterized in that the cold head of the refrigerator is disposed in a neck tube, the upper end of which is connected to the outer shell of the cryostat and the lower end of which is connected to the helium tank in such a manner that the neck tube and the helium tank delimit a helium space, with at least one cooling circuit with thermally insulated transfer lines being provided between the helium space and the NMR probe head, wherein the cryogenic helium in the helium space is used as coolant for the