Device for regulating pressure in helium tank of NMR magnet, comprising two pressure sensors

Abstract

The invention relates to a device (1) for regulating a pressure in a helium tank (2) of an NMR magnet (23), comprising:-a first pressure sensor (6) for measuring a first pressure in the helium tank (2),-a regulating valve (5) for regulating a helium flow flowing out of the helium tank (2),-an electronic regulating device (13) for actuating the regulating valve (5), the electronic control device (13) is designed to obtain a first pressure value D1 measured by the first pressure sensor (6) and to adjust the position of the control valve (5) as a function of the measured first pressure value D1, the first pressure value D1 being adjusted to a predetermined setpoint value SW, the setpoint value SW being adjusted to a predetermined setpoint value SW, and the setpoint value SW being adjusted to a predetermined setpoint value SW. The device (1) further comprises:-at least one second pressure sensor (7; 7 ') for measuring a second pressure outside the helium tank (2); 7a) of the second pressure sensor (7; 7a), the electronic control device (13) being further designed to obtain a signal from the second pressure sensor (7; the setpoint value SW is determined as a function of the second pressure value D2 measured by the first pressure value D1 and the second pressure value D2, and wherein the control device (13) is designed to control the setpoint value SW as soon as the difference DIF = D1-D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds a predetermined threshold value, and wherein the setpoint value SW is determined as a function of the setpoint value SW. If so, the target value SW for the pressure in the helium tank (2) is varied step by step. The apparatus improves the availability of the NMR magnet.

Description

Technical Field

[0001] This invention relates to a device for regulating pressure in a helium tank of an NMR magnet, comprising:

[0002] - A first pressure sensor for measuring the first pressure in the helium tank.

[0003] - A regulating valve for adjusting the flow of helium from the helium tank.

[0004] - An electronic regulating device for operating the regulating valve, wherein the electronic regulating device is designed for,

[0005] - Obtain the first pressure value D1 measured by the first pressure sensor.

[0006] - And the position of the regulating valve is adjusted based on the measured first pressure value D1, wherein the first pressure value D1 is adjusted to a predetermined theoretical value SW. Background Technology

[0007] Such a device is known from the corporate publication “EAPD II - Electronic Atmospheric Pressure Device II User Manual Version 002” issued by Bruker Corporation, Billerica, MA, USA on January 20, 2020.

[0008] Superconducting magnets used in NMR devices, such as NMR spectrometers or NMR tomography scanners, are often cooled with liquid helium. Cryostats here have vacuum-isolated containers containing boiling liquid helium and the superconducting magnets.

[0009] The pressure inside the helium tank should be above the ambient atmospheric pressure to prevent air from being drawn into the tank. Inhaled air can cause ice formation due to moisture or other air components, such as frozen nitrogen, which can clog conduits or valves and thereby jeopardize operational safety.

[0010] Furthermore, the pressure in the helium tank should be kept as constant as possible, because pressure fluctuations in the helium tank can cause artifacts in NMR measurements, such as those caused by minimal deformation of the helium tank and movement of the superconducting magnet.

[0011] In many applications, helium tanks are equipped with spring-loaded overpressure valves that mechanically establish a fixed pressure difference between the helium tank pressure and atmospheric pressure. Correspondingly, the pressure in the helium tank then depends on atmospheric pressure, and the tank pressure fluctuates with weather-dependent atmospheric pressure. This can result in noticeable artifacts in NMR measurements depending on weather changes.

[0012] Referring to the above, using Bruker's "EAPD 11," a pressure sensor is used to adjust the pressure in the helium tank of the NMR magnet to a predetermined, fixed theoretical value. For this purpose, an electronic control unit operates a regulating valve through which helium gas can flow from the tank. A recommended theoretical pressure is approximately 15 mbar above the expected maximum atmospheric pressure for the location. This ensures a well-maintained, constant helium tank pressure in most cases and prevents air intake.

[0013] However, atmospheric pressure can fluctuate dramatically in many locations. For example, during hurricane season in the southern and eastern United States, pressure drops of up to approximately 100 millibars can occur. At such times, the pressure difference between the helium tank pressure and atmospheric pressure can be so large that the safety overpressure valve opens to release helium, and NMR measurements are no longer possible under stable conditions. With very large pressure differences, even the helium tank's venting diaphragm may rupture.

[0014] In many cryogenic systems, it is also necessary to periodically refill with liquid helium. To introduce the transfer line, the helium tank must be opened to the atmosphere. If the pressure in the helium tank drops suddenly when opened to atmospheric pressure, a large amount of cold helium gas is released suddenly. The enthalpy of this cold helium gas cannot be used to capture heat, which is energy-disadvantageous.

[0015] US3412568A discloses a pressure regulator that can be used to adjust a constant pressure in a cryogenic thermostat having a coolant bath.

[0016] As known from JP2015060973A, the pressure in the helium tank of the cryogenic thermostat is adjusted by means of an electric heater.

[0017] As known from DE102005058650B3, in an MRT device, optical devices are used to monitor the continuity of the tower tube of a cryogenic magnet.

[0018] US2009 / 0280989A1 describes a control device and method for regulating gas pressure and gas flow rate in a cryogenic container used for superconducting magnet coils. The pressure inside the container and in the environment is measured using sensors. The pressure in the container can be controlled as a function of the ambient pressure. Furthermore, the gradual pressure reduction within the container is described.

[0019] US2009 / 0261830A1 describes an imaging magnetic resonance scanner. Pressures in the cryogenic container and at environment are measured and input into a processor that operates a pressure regulator to achieve the largest possible buffer before an overpressure valve opens. This avoids unnecessary coolant loss. In one example, the pressure in the cryogenic container is maintained above ambient pressure by 0.1 psi (approximately 689 Pa). Summary of the Invention

[0020] The objective of this invention is to introduce a device for regulating pressure in a helium tank, which enables improved operational safety and greater user-friendliness.

[0021] Description of the present invention

[0022] This task is solved according to the invention by means of a device of the type described at the beginning, characterized in that the device further comprises:

[0023] - At least one second pressure sensor for measuring a second pressure outside the helium tank.

[0024] Furthermore, the electronic regulation device is also designed for,

[0025] - Obtain the second pressure value D2 measured by the second pressure sensor.

[0026] - and the theoretical value SW is determined based on the second pressure value D2.

[0027] The present invention is configured to include a first pressure sensor for monitoring a first pressure (“helium tank pressure”) within a helium tank, and a second pressure sensor for monitoring a second pressure outside the helium tank. The second pressure is typically atmospheric pressure or another pressure dependent on atmospheric pressure, such as the pressure in a helium recovery system (which is typically above atmospheric pressure by a small pressure difference). The second pressure, or the associated second pressure value D2 measured by the second pressure sensor, is incorporated into the control of the helium tank pressure at least by the theoretical value to be set for the helium tank pressure (i.e., the theoretical value for the first pressure value D1 to be measured). This allows for the achievement of suitable operating conditions with (at least temporarily) stable helium tank pressure and thereby stable measurement conditions under fluctuating environmental conditions (as can be seen from the fluctuating second pressure value D2) while maintaining good operational safety. Furthermore, it is possible to convert the helium tank pressure in a desired manner with respect to the second pressure in order to obtain high energy efficiency when utilizing liquid helium in the system. Finally, hazardous operating conditions (e.g., a high pressure difference between D1 and D2) can be more easily identified to improve operational safety through alarms to users or automatic responses.

[0028] This allows for the initial pressure setting in the helium tank. Specifically, a theoretical value SW is predetermined in the regulating device for the pressure in the helium tank, and the measured first pressure value D1 is adjusted to the theoretical value SW by manipulating the regulating valve through the regulating device. To reduce the pressure in the helium tank, the regulating valve can be further opened and / or held in the open position, and to increase the pressure in the helium tank, the regulating valve can be further closed and / or held in the closed position. Regulation methods known per se, such as P-, I-, PI-, PD-, or PID-, can be used.

[0029] According to the present invention, the theoretical pressure SW in the helium tank is determined in the regulating device taking into account the (current) measured second pressure value D2, and if necessary, also taking into account the (current) measured first pressure value D1 and the programmed specifications. That is, within the range from the first pressure value D1 to the theoretical value SW, the regulating valve is adjusted not only according to the first pressure value D1 but also according to the second pressure value D2 and the programmed specifications.

[0030] The electronic regulator (when there is no operational malfunction, at a constant theoretical value or at a theoretical value that varies only slowly, such as at a theoretical value of 10 mbar / h or less, typically 5 mbar / h or less) always keeps the measured first pressure value D1 close to the theoretical value SW, typically with a deviation of up to 1 mbar, preferably up to 0.5 mbar, and particularly preferably up to 0.25 mbar.

[0031] During normal operation for NMR measurements, the theoretical value SW typically remains constant (at least for the duration of the NMR measurement), and correspondingly, the pressure in the helium tank is always kept close to the theoretical value through regulation. In specific operating conditions, such as for refilling liquid helium, a predetermined process of pressure variation in the helium tank can be programmed, such as a gradual decrease in the helium tank pressure to atmospheric pressure to prepare for opening the helium tank for introducing the injection fitting, or a gradual increase in the helium tank pressure from atmospheric pressure back to the normal operating pressure; for this purpose, the predetermined theoretical value is correspondingly changed over time by a regulating device. Atmospheric pressure (or pressure in the helium recovery system) can be determined here by a second pressure sensor.

[0032] A second pressure sensor or second pressure value can be used to identify when a change in the theoretical value SW of the helium tank pressure is required for reliable continued operation, such as due to drastic weather changes. Similarly, the second pressure sensor or second pressure value D2 can be used to design processes that favor the desired energy changes in pressure and / or helium flow.

[0033] It should be noted that within the scope of this invention, the pressure or pressure value of interest can be measured directly, or indirectly by the difference between the pressure or pressure value of interest and other known pressures or pressure values. For example, when the helium tank pressure is known by a first pressure value D1, a second pressure value D2 of atmospheric pressure can be measured by the pressure difference between the atmosphere and the helium tank.

[0034] Implementation forms of sensors

[0035] In a preferred embodiment of the device according to the invention, the second pressure is the pressure in the surrounding atmosphere. The pressure of the surrounding atmosphere (also simply referred to as atmospheric pressure) is particularly relevant to operational safety, especially because the safety devices of the helium tank (overpressure valve and vent) react to the pressure difference between the helium tank pressure and atmospheric pressure. Furthermore, when the helium tank should be opened (e.g., to prepare for helium transfer), the helium tank pressure can be reduced to atmospheric pressure with good accuracy (through a programmed change process of theoretical pressure).

[0036] Also preferred is an implementation where the second pressure is the pressure within the helium recovery system. Using a helium recovery system, valuable helium evaporated from the helium tank can be collected and, for example, used for reliquefaction and accumulation. The pressure in the helium recovery system is typically slightly (usually up to 5 mbar) above atmospheric pressure. When the helium recovery system is connected to a helium line leading from the helium tank, the pressure in the helium tank can only drop down to the pressure in the helium recovery system, which can then be easily calibrated using a second pressure sensor.

[0037] A particularly preferred embodiment, in which the device further includes:

[0038] - A third pressure sensor for measuring a third pressure outside the helium tank.

[0039] The second and third pressures include the pressure in the surrounding atmosphere and the pressure in the helium recovery system. For example, the second pressure sensor measures the pressure in the surrounding atmosphere, and the third pressure sensor measures the pressure in the helium recovery system. By measuring the second and third pressures, disturbances in the helium recovery system (such as accidentally closed valves or malfunctioning compressors) can be easily identified. A typical disturbance condition (and thus a typical alarm condition) is a pressure in the helium recovery system that is significantly higher than atmospheric pressure (e.g., more than 5 millibars).

[0040] A particularly preferred embodiment further includes:

[0041] - A flow sensor for measuring the helium flow rate value of the helium gas flowing out of the helium tank. The flow sensor is connected in series with a regulating valve (typically in the helium pipeline led out). The use of the flow sensor enables extended monitoring and analysis possibilities. In particular, dangerous icing can be easily identified, which blocks the outflow of helium from the helium tank.

[0042] An advantageous embodiment is one in which the regulating device includes a storage device or a connection for a storage device, and the sensor values obtained by the regulating device are recorded using the storage device. By storing the sensor data, the sensor data is available for subsequent analysis. In particular, artifacts in NMR measurements due to pressure fluctuations in the helium tank and / or outside the helium tank can be compensated, or the helium consumption of the laboratory or NMR magnet can be analyzed. Typically, the storage device also records the generated control information, such as the corresponding current theoretical value for the helium tank pressure or the control instruction to the regulating valve. The storage device usually records the operation for a predetermined elapsed time interval, such as the last 30 days or the last 180 days.

[0043] Embodiments related to the regulation of tank pressure

[0044] A particularly preferred embodiment is provided such that the regulating device is designed to gradually change the theoretical value SW for the pressure in the helium tank once the difference DIF = D₁ - D₂ between the measured first pressure value D₁ and the measured second pressure value D₂ reaches or exceeds a predetermined threshold, especially where, when the difference DIF is less than or equal to the lift threshold HSW, the theoretical value SW is increased by one level, and when the difference DIF is greater than or equal to the decrease threshold SSW, the theoretical value SW is decreased by one level, where HSW < SSW. This improves the availability of the NMR magnet. By the gradual change of the theoretical value, the frequency of the change of the theoretical value (and thus the corresponding change in the pressure in the helium tank) can be kept small, and correspondingly, only rarely is an interruption of the measurement operation required.

[0045] Due to weather changes, the atmospheric pressure may also change relatively strongly.

[0046] When the atmospheric pressure rises strongly and exceeds the currently set theoretical value for the first pressure value or the helium tank pressure, the regulating device is no longer able to keep the helium tank pressure constant because the regulating device depends on the pressure drop existing from the helium tank to the helium receiving end (atmosphere or helium recovery system). In order to further ensure a stable pressure in the helium tank at this time, the previous theoretical value is changed to a new higher theoretical value in one step. During the conversion of the pressure in the helium tank to the new theoretical value, the NMR measurement is disturbed. However, a stable pressure in the helium tank can be maintained again thereafter.

[0047] When atmospheric pressure drops significantly below the current theoretical pressure used for the helium tank, helium leaks from the tank through safety devices (overpressure valves or even vents). In this situation, the pressure in the helium tank becomes unstable, valuable helium is lost, and the vents require repair. To prevent this, the theoretical pressure is changed in stages to a new, lower theoretical value. During this pressure transition in the helium tank to the new theoretical value, NMR measurements are disturbed. However, a stable pressure can then be maintained in the helium tank again.

[0048] It's important to note that the theoretical value can be changed from the previous theoretical value in stages to a new theoretical value; that is, multiple partial changes can be made until the new theoretical value is reached. Similarly, continuous changes (e.g., with a linear theoretical value ramp) can be made until a new theoretical value is reached. This allows us to define the pressure change per unit time within the helium tank.

[0049] The level here represents the difference between the old and new theoretical values, where continuous operation / measurement operation of the helium tank or the NMR magnet has been set or configured at said theoretical values. Typically, the level is selected in the range of 5-25 mbar, preferably 8 and 20 mbar, and particularly preferably 10 and 15 mbar. It should be noted that the level at which the theoretical value decreases may differ from the level at which it increases. Furthermore, it should be noted that the level should not be chosen too small, and the raising and lowering thresholds should not be chosen too close together, in order to limit the frequency of theoretical value switching and maintain a high degree of availability of the NMR measurement setup. The new threshold is typically changed by a predetermined level relative to the current theoretical value; however, it is also possible that the new threshold is determined relative to the current pressure value (e.g., current atmospheric pressure).

[0050] By raising the threshold HSW and lowering the threshold SSW, an effective range for the difference DIF is designed, and when the difference DIF leaves this range, it adapts to the theoretical value SW. As long as the DIF remains within the range, the theoretical value remains constant.

[0051] Furthermore, a particularly preferred embodiment is wherein the regulating device is designed to convert the theoretical value SW for the pressure in the helium tank to a target value ZW over a predetermined duration, wherein the target value ZW depends on a second pressure value D2, and in particular, the duration can be selected by the user.

[0052] Thus, within the range of continuous adjustment from the first pressure value D1 to the theoretical value that varies (slowly) over time, the helium tank pressure can be energy-efficiently converted to the target value.

[0053] This feature is particularly useful for the preparation of helium transport (filling helium tanks with liquid helium). It should be noted that helium transport is typically planned several days in advance. For helium transport to proceed, the helium tank must be opened to atmospheric pressure (at the inlet provided for this purpose).

[0054] Rapid pressure changes within a helium canister are energy-disadvantageous. This is especially true of rapid pressure drops, such as those occurring when a helium canister is suddenly opened, where the canister pressure is above atmospheric pressure. The gas, which was slightly pressurized before opening, suddenly escapes. The enthalpy of this gas cannot be used for cooling purposes (e.g., on the canister suspension). Furthermore, a large amount of cold gas escapes due to the sudden increase in the evaporation rate of boiling helium (which can also trigger a quench), and the enthalpy of this cold gas is also unusable.

[0055] When the theoretical value depends on changes in the second pressure value, a slow and precise conversion can be made to the desired target value (usually atmospheric pressure itself) that depends on the second pressure, for example, by a change of 10 mbar / h or less, or preferably 5 mbar / h or less of the theoretical value. The user can schedule the duration of the conversion so that the desired target value is reached at a specific time, such as when helium transport is to begin as scheduled.

[0056] In a preferred further improvement of this embodiment, the target value ZW is configured to correspond to a second pressure value D2, i.e., ZW = D2, or the target value ZW is above the second pressure value D2 with a small pressure addition DA, i.e., ZW = D2 + DA and where DA ≤ 3 mbar. Using ZW = D2 (where the second pressure is atmospheric pressure), opening to the atmosphere can be performed without a pressure drop. When ZW = D2 + DA (where the second pressure is atmospheric pressure), a small overpressure can be maintained in the helium tank for a relatively long time, and also at the end of the conversion, which prevents the entry of contaminants.

[0057] Advantageously, a further configuration is provided in which the adjustment device is designed to linearly transform the theoretical value SW to the target value ZW over time. This is particularly simple and can be set up especially through software programming.

[0058] In an alternative further configuration, the regulating device is designed to cause the theoretical value SW to change non-linearly over time, wherein the helium flow rate through the regulating valve remains substantially constant during the duration during which the theoretical value SW transitions to the target value ZW.

[0059] The conversion curve used for the theoretical value can be calculated / determined in advance as a function of time, thereby achieving a substantially constant helium flow rate. Alternatively, a flow meter can be installed to measure the helium flow rate of the gas stream exiting the helium tank through the regulating valve, and the regulating device can use the measured helium flow rate as another regulating amount.

[0060] The pressure and temperature of boiling helium in a helium tank are correlated via a vapor pressure curve. This, of course, only applies to liquids on a surface, because helium has relatively poor thermal conductivity. A temporary temperature gradient is formed within liquid helium as pressure changes occur.

[0061] As the pressure in the helium tank increases rapidly, the temperature of the liquid helium on the surface rises. The liquid helium below the surface remains cooler and only slowly heats up to the surface temperature. During this time, less liquid helium evaporates than would be expected from the heat load on the helium tank because the helium below the surface absorbs heat with its considerable heat capacity.

[0062] As the pressure in the helium tank drops rapidly, the temperature of the liquid helium on the surface decreases. The liquid helium below the surface remains hotter and cools only slowly to the surface temperature. During this time, more liquid helium evaporates than is expected from the heat load on the helium tank because energy must be extracted from the helium below the surface for cooling. This cooling power is provided by the increased evaporation.

[0063] If the helium flow rate is kept approximately constant, the enthalpy of the cold gas can be utilized optimally. Typically, the helium flow rate is kept constant with an accuracy of + / -20% (or more accurately), preferably -+ / -15% (or more accurately), and particularly preferably + / -10% (or more accurately) near the target helium flow rate.

[0064] In a preferred sub-variation of this further configuration, the regulating device is designed to cause the theoretical value SW to decrease more rapidly at the start of the transition than near the end of the transition as the theoretical value SW transitions to the target value ZW. It is advantageous to initially reduce the pressure more rapidly during the pressure drop in the helium tank (to artificially accelerate the initial evaporation) and then reduce the pressure more slowly near the end of the pressure reduction phase (to maintain a constant evaporation rate).

[0065] Implementation forms for alarm devices and alarm situations

[0066] A particularly advantageous embodiment includes an alarm device that automatically triggers an alarm message in one or more predetermined alarm conditions. Specifically, the alarm device includes a sound signal generator and / or an optical signal generator and / or a radio signal generator and / or a data signal generator. The alarm message can alert the user to a dangerous condition or prompt them to stop and further inspect the cryostat system. The alarm message can also trigger or automatically implement manual troubleshooting or safety measures.

[0067] A preferred further configuration of this embodiment includes an alarm condition where the pressure value D1 of the helium tank drops below the atmospheric pressure value D2. When the pressure in the helium tank is below atmospheric pressure, a potentially hazardous situation arises because contaminants can be drawn into the helium tank through small leaks. This particularly concerns the drawn-in air, whose components (e.g., nitrogen) or moisture may freeze inside the helium tank and cause it to ice up. This hazardous situation can occur, especially in systems with active cooling, when cooling is “too intense,” i.e., when active cooling overcompensates the heat load on the helium tank.

[0068] Advantageously, another configuration includes an alarm condition where the pressure value D1 of the helium tank exceeds a predetermined maximum helium tank pressure. Specifically, a first alarm condition for D1 includes the pressure value D1 exceeding a predetermined first maximum helium tank pressure EHM, and a second alarm condition for D1 includes the pressure value D1 exceeding a predetermined second maximum helium tank pressure ZHM, where ZHM > EHM, and the alarm message differs for the first and second alarm conditions for D1.

[0069] The helium tank pressure above the predetermined maximum pressure can indicate different types of malfunctions, such as a blocked helium line or a malfunction causing an increased helium flow rate (see below). When the cryostat and the equipment (including regulating valves and, if necessary, a helium recovery system and, if necessary, active cooling) are functioning correctly, an increased helium pressure indicates a malfunction in the superconducting NMR magnet that leads to an increased evaporation rate and may even trigger a quench. The maximum value can be set such that it is to be reached or alternatively, when the opening pressure of a safety device (overpressure valve or vent) is reached. If two thresholds (EHM and ZHM) are designed, typically the first maximum helium tank pressure (EHM) is configured for the triggering of the overpressure valve (which can be caused, for example, by an unintentionally closed valve at the magnet outlet), and the second maximum helium tank pressure (ZHM) is configured for the triggering / damage of the vent (typically in the case of a quench, i.e., the sudden loss of superconductivity in the NMR magnet, a "quench alarm").

[0070] Furthermore, a preferred configuration includes an alarm condition where the measured helium flow rate exceeds a predetermined maximum helium flow rate. An increased helium flow rate typically indicates a problem in the NMR magnet, such as defective active cooling, a fault in the thermal insulation, a switch opening, or a malfunctioning connector.

[0071] A preferred sub-variation of this further configuration is that the predetermined maximum helium flow rate depends on current or recent controlled changes in the helium tank pressure, particularly that the maximum helium flow rate is higher during and / or immediately after a pressure reduction in the helium tank than when the helium tank pressure is under constant control. When the pressure in the helium tank decreases, a short-term (planned) increase in the helium flow rate exceeding the normal value occurs. This should not trigger an alarm. Due to the poor thermal conductivity of liquid helium, as mentioned above, the helium flow rate also increases over a certain period after the pressure reduction. This short period can typically be set to 3 hours or less, usually 2 hours or less. Typically, this controls the change in the helium tank pressure, i.e., changes the predetermined theoretical value SW of the helium tank pressure.

[0072] Furthermore, an advantageous configuration includes an alarm condition where the measured helium flow rate is below a predetermined minimum helium flow rate. When the helium flow rate is too low, this could indicate a leak in the piping between the helium tank and the flow sensor, a leak in the helium tank, icing in the helium tank, or icing in the piping leading from the helium tank to the flow sensor. It could also simply mean that the NMR magnet is not connected to the monitoring (i.e., the device according to the invention).

[0073] Advantageously, a further variant of this configuration allows the predetermined minimum helium flow rate to depend on current or recent changes in the helium tank pressure, particularly where the minimum flow rate is lower during and / or immediately after an increase in the helium tank pressure compared to a constant pressure. When the pressure in the helium tank increases, the helium flow rate briefly drops below normal. This should not trigger an alarm. Due to the poor thermal conductivity of liquid helium, as mentioned above, the helium flow rate also decreases over a certain period after the pressure increase. It should be noted that the predetermined minimum helium flow rate can even be set to "zero" during and / or shortly after an increase in the helium tank pressure, so that a "zero" helium flow rate during this period also does not trigger an alarm message. This short period can typically be set to 3 hours or less, typically 2 hours or less.

[0074] Advantageously, a further configuration is provided in which the alarm condition includes a measured helium flow rate of zero and simultaneously the current position of the regulating valve or the position of the regulating valve currently operated by the regulating device is not closed. A flow rate drop to zero indicates dangerous complete freezing of the cryostat or at least the outgoing helium line. However, the regulating state should be considered here: an alarm should not be triggered when the regulating valve is (as planned) fully closed, for example, to cause an (intentional) increase in pressure in the helium tank. Freezing of the cryostat (or outgoing helium line) is a dangerous situation. The suspension tube is then blocked, and helium can no longer leak from the helium tank, which normally flows out through the suspension tube. Because helium continues to evaporate in the helium tank due to heat input, pressure builds up in the helium tank until it ruptures. In NMR magnets, it is recommended to periodically check whether helium is escaping from the helium tank's outlet. This monitoring can be performed continuously and automatically within the scope of the invention.

[0075] Furthermore, a preferred configuration includes an alarm condition where the measured helium flow rate is zero, and simultaneously the pressure value D2 in the helium recovery system rises until it reaches the pressure value D1 in the helium tank. This function distinguishes between the presence of icing and the presence of a closed valve only in the helium recovery system. In both cases, the helium flow rate drops to zero; in the case of icing, the measured recovery system pressure does not rise, while in the case of a closed valve, the recovery system pressure rises. That is, this alarm condition identifies a closed valve in the helium recovery system.

[0076] Furthermore, a preferred configuration includes an alarm condition where the difference between the pressure value DHR measured in the helium recovery system and the pressure value DAT measured in the surrounding atmosphere, DHA = DHR - DAT, exceeds a predetermined threshold SWW, specifically where SWW is selected in the range of 2.5 mbar to 20 mbar. Typically, SWW is also selected to be greater than 5 mbar. This function identifies faults in the helium recovery system, such as a defective compressor.

[0077] In an advantageous further configuration, at least a portion of the alarm conditions includes the current position of the control valve or the position of the control valve currently operated by the control device. This allows for targeted detection of hazardous conditions or malfunctions in many situations and makes them easier to distinguish from desired operating conditions. For example, the disappearance of measured helium flow is non-critical when a control valve is simultaneously operated to close as planned.

[0078] Methods for pressure regulation

[0079] Methods for adjusting the pressure in the helium tank of an NMR magnet also fall within the scope of this invention.

[0080] Specifically, a first pressure sensor is used to measure the first pressure in the helium tank.

[0081] Specifically, the flow of helium from the helium tank is regulated using a regulating valve.

[0082] The electronic regulating device controls the regulating valve, and the electronic regulating device...

[0083] - Obtain the first pressure value D1 measured by the first pressure sensor.

[0084] - And the position of the regulating valve is adjusted based on the measured first pressure value D1, so that the first pressure value D1 is adjusted to a predetermined theoretical value SW, characterized in that a second pressure outside the helium tank is measured using at least one second pressure sensor, and the electronic regulating device further...

[0085] - Obtain the second pressure value D2 measured by the second pressure sensor.

[0086] - and the theoretical value SW is determined based on the measured second pressure value D2.

[0087] In particular, the method is implemented when using the equipment according to any one of the preceding claims. Improved operational safety and greater user-friendliness can be achieved by utilizing the method according to the invention for regulating pressure in the helium tank.

[0088] In particular, it is possible to change the current theoretical value used for the helium tank pressure (using which a substantially constant helium tank pressure is designed) to a new theoretical value when needed (using which a substantially constant helium tank pressure can then be designed again after a short disturbance). This change requirement can be identified by measuring a second pressure value D2 (and a first pressure value D1). Typically, this change requirement is that the second pressure value D2 (which represents atmospheric pressure or another pressure dependent on atmospheric pressure, such as in a helium recovery system) can identify that the pressure drop required for regulation between the helium tank and the subsequent helium receiving end (other facilities after the regulating valve) is too small, or that the pressure drop between the helium tank and the surrounding atmosphere becomes so large that safety devices (overpressure valves or vents) may be triggered. This theoretical value change typically occurs in a stepped manner.

[0089] Similarly, the helium tank pressure can be slowly converted to the target value relative to the second pressure through a corresponding programmed theoretical value in a defined manner, so as to make particularly efficient use of the cooling effect of the gas escaping from the helium tank.

[0090] Finally, a second pressure sensor can also be used to identify some dangerous situations.

[0091] A particularly preferred embodiment of the method according to the invention is a variant wherein,

[0092] Once the difference DIF = D1 - D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds a predetermined threshold, the regulating device gradually changes the theoretical value SW used for the pressure in the helium tank.

[0093] Specifically, when the difference DIF is less than or equal to the raising threshold HSW, the theoretical value SW increases by one level, and when the difference DIF is greater than or equal to the lowering threshold SSW, the theoretical value decreases by one level, where HSW <SSW,

[0094] In particular, the method is implemented when using the apparatus according to claim 7. A well-stabilized helium tank pressure can be designed in this way between progressive changes in the theoretical value, allowing for high-precision NMR measurements. Simultaneously, the NMR magnet or its cryostat, including the helium tank, can be operated safely, especially in the absence of regulation failure or air intake and without triggering safety devices due to excessive pressure differentials.

[0095] Furthermore, a preferred variation is configured such that,

[0096] The regulating device converts the theoretical value SW of the pressure in the helium tank to a target value ZW over a predetermined duration, wherein the target value ZW depends on a second pressure value D2, and in particular, the duration can be selected by the user, especially when the method is implemented using the device according to claim 8. By using a target value ZW dependent on the second pressure value D2, a defined final state with desired characteristics can be reliably achieved relative to the second pressure, and in particular, subsequent actions such as opening the helium tank to the atmosphere can be reliably performed under desired conditions (desired pressure conditions). In particular, a strong, sudden pressure drop can be avoided, for example, before helium transfer, when the helium tank is opened to the atmosphere. Furthermore, a desired energy-efficient curve for the helium pressure can be designed by programming the conversion of the theoretical value, thereby enabling high energy efficiency; the conversion (change of the theoretical value) is typically continuous and monotonous, preferably strictly monotonous. The conversion is carried out in such a way that the first pressure value D1 is always kept close to the theoretical value SW (this can be achieved by a suitable adjustment rate, taking into account the interaction between the regulating device and the NMR magnet, see above).

[0097] A further improvement to this variant is preferred, wherein the regulating device changes the theoretical value SW non-linearly over time, wherein the helium flow rate through the regulating valve is kept substantially constant during the duration during which the theoretical value SW transitions to the target value ZW, particularly when the method is implemented using the apparatus according to claim 11. By non-linearly changing the theoretical value, the temperature gradient in the liquid helium that occurs in the helium tank during controlled pressure changes can be taken into account, which acts on the helium evaporation rate and is eliminated only over a certain period of time. By non-linearly changing the theoretical value or the controlled pressure change in the helium tank, a substantially constant evaporation rate of helium (corresponding to a constant helium flow rate) that is particularly advantageous in terms of energy can then be set.

[0098] Furthermore, a preferred embodiment of the method according to the invention is configured such that,

[0099] The alarm device automatically triggers an alarm message in one or more predetermined alarm situations.

[0100] In particular, the alarm device includes a sound signal generator and / or an optical signal generator and / or a radio signal generator and / or a data signal generator, and the alarm condition includes a measured helium flow rate of the helium gas flowing from the helium tank through the regulating valve being zero and the regulating valve not being closed in its current position or in the position currently operated by the regulating device.

[0101] In particular, the method is implemented when using the apparatus according to claim 20. Despite the presence of an open regulating valve, a helium flow rate of zero indicates a dangerous freezing of the helium tank or the helium pipeline leading from the helium tank, including the regulating valve; this state is identified and reported using the set function, especially in order to introduce countermeasures or safety measures. When the regulating device is to (plannedly) increase the pressure in the helium tank, for example due to a strong rise in ambient pressure caused by weather, the regulating device (plannedly) closes the regulating valve, and the helium flow rate (plannedly) drops to zero for a period of time, which does not trigger an alarm at this time.

[0102] Low-temperature thermostat arrangement and NMR measurement arrangement

[0103] Furthermore, a cryostat arrangement structure is included within the scope of this invention, comprising:

[0104] -A vacuum-sealed helium container, and

[0105] According to the above-described device of the present invention,

[0106] The first pressure sensor is connected to the helium tank, and the second pressure sensor is connected to a location outside the helium tank, specifically connected to the ambient atmosphere or a helium recovery system. The regulating valve is located in the helium pipeline leading from the helium tank. This cryogenic thermostat arrangement allows for pressure regulation within the helium tank with improved operational safety and high user-friendliness.

[0107] A preferred embodiment of the cryostat arrangement according to the invention further includes a helium recovery system connected to the outgoing helium line. This allows for the collection and storage, and especially for reuse, of valuable evaporated helium, particularly after reliquefaction, to further cool the NMR magnet.

[0108] Furthermore, an NMR measurement arrangement structure is also included within the scope of this invention, comprising:

[0109] -According to the above-described low-temperature thermostat arrangement structure of the present invention

[0110] - The superconducting NMR magnet in the helium tank of the cryostat arrangement structure.

[0111] -NMR sample head, the NMR sample head extending into the room temperature orifice of the vacuum-isolated helium container, and

[0112] - An NMR spectrometer control unit for manipulating NMR measurements using the NMR sample head. Utilizing this NMR measurement setup, high-resolution NMR measurements can be performed with high operational safety and user-friendliness, especially while avoiding artifacts caused by pressure fluctuations in the helium tank.

[0113] The application of the NMR measurement arrangement structure described above according to the present invention for performing NMR measurements is also included within the scope of the present invention, wherein the electronic regulating device communicates the state of the helium tank pressure regulation to the NMR spectrometer control device, and wherein the NMR spectrometer control device suspends the NMR measurement during periods of pressure instability in the helium tank. This avoids artifacts in the NMR measurement. A typical time for suspending the NMR measurement due to pressure instability is during which the regulating device manipulates a change in the theoretical value, and the pressure in the helium tank changes accordingly. Alternatively, the NMR measurement can be suspended immediately following the change in the theoretical value, while also compensating for the temperature gradient in the liquid helium (i.e., the helium tank and therefore the pressure in the helium tank are not yet in thermal equilibrium); the subsequent time is typically in the range of up to three hours and can often be identified in helium flow rates that are not yet constant (or corresponding changes in the control valve's operation or actual position). During the change in helium flow rate, the temperature distribution in the cryostat can also change, which can again cause, for example, a change in length on the suspension of the helium tank; such a change in length can cause artifacts in NMR measurements. Attached Figure Description

[0114] Other advantages of the invention become apparent from the specification and drawings. Similarly, the features described above and further illustrated can be used individually or in any combination according to the invention. The illustrated and illustrated embodiments should not be construed as a final enumeration, but rather as exemplary features used to describe the invention.

[0115] Detailed description and accompanying drawings of the present invention

[0116] Figure 1 The illustration schematically depicts a first embodiment of the device according to the invention for regulating the pressure in a helium tank, wherein a second pressure in the surrounding atmosphere is determined using a second pressure sensor;

[0117] Figure 2 The schematic illustration shows a second embodiment of the device according to the invention, wherein a second pressure in the surrounding atmosphere is determined using a second pressure sensor, and an outflowing helium flow is measured using a flow sensor.

[0118] Figure 3The schematic illustration shows a third embodiment of the device according to the invention, wherein a second pressure in the helium recovery system is determined using a second pressure sensor;

[0119] Figure 4 The schematic illustration shows a fourth embodiment of the device according to the invention, wherein a second pressure in the surrounding atmosphere is determined using a second pressure sensor and a third pressure in the helium recovery system is determined using a third pressure sensor.

[0120] Figure 5 Schematic illustration of a device according to the present invention Figure 4 The fifth embodiment of the implementation, wherein an additional pipeline segment is provided for the outflow of helium in the event of a power outage;

[0121] Figure 6 The schematic diagram illustrates one embodiment of the NMR measurement arrangement according to the present invention, which includes one embodiment of the cryostat arrangement according to the present invention, wherein the cryostat arrangement has, as described herein, [the specific configuration is missing from the original text]. Figure 5 The device according to the present invention is configured in the form of an embodiment;

[0122] Figure 7 The schematic diagram illustrates a first variation of the method according to the invention for adjusting the pressure in a helium tank, wherein the theoretical value for the pressure in the helium tank decreases along a linear ramp to a target value corresponding to the measured atmospheric pressure.

[0123] Figure 8 The schematic diagram illustrates a second variation of the method according to the invention for adjusting the pressure in a helium tank, wherein the theoretical value for the pressure in the helium tank decreases along a nonlinear ramp to a target value corresponding to the measured atmospheric pressure.

[0124] Figure 9 The schematic diagram illustrates a third variation of the method for adjusting the pressure in the helium tank, wherein the theoretical value of the pressure in the helium tank is changed step by step.

[0125] Figure 10 The diagram schematically illustrates the inspection procedure for determining icing in a cryostat and the corresponding output of an alarm message, wherein the inspection procedure can be used in a method according to the invention for regulating pressure in a helium tank. Detailed Implementation

[0126] Figure 1 A first embodiment of the device 1 according to the invention is schematically shown for adjusting the pressure in the helium tank 2 of the NMR magnet.

[0127] Helium line 3, extending from helium tank 2, connects helium tank 2 to helium recovery system 4. An automatically operable regulating valve 5 is integrated into helium line 3. The regulating valve 5 is operated, for example, by an electric motor (not shown further). A first pressure sensor 6 is also located upstream of the regulating valve 5 in helium line 3, which allows for the measurement of the pressure in helium tank 2.

[0128] The first pressure value D1 determined by the first pressure sensor 6 is controlled by an electronic adjustment device (not shown further here, but referenced for this purpose). Figure 6 The pressure is read and compared with the predetermined theoretical value SW for the helium tank pressure. The regulating device operates the regulating valve 5 in such a way that the helium tank pressure, or the first pressure value D1 measured, is adjusted to the theoretical value SW. When the adjustment is working correctly (i.e., there is no interference / malfunction), the first pressure value D1 will always remain close to the theoretical value SW, typically with a deviation of 1 mbar or less.

[0129] Furthermore, a second pressure sensor 7 is provided, which measures the pressure difference between the pressure inside the helium tank and the pressure of the surrounding atmosphere atm. This (and, using the knowledge of the first pressure value D1) indirectly measures the second pressure outside the helium tank 2, the atmospheric pressure here. The corresponding second pressure value D2 of the atmospheric pressure is evaluated by the regulating device, wherein the regulating device determines a predetermined theoretical value SW by means of the second pressure value D2, and uses this theoretical value to adjust the regulating valve 5.

[0130] It should be noted that atmospheric pressure depends on the weather and changes over time, and may also change drastically under corresponding weather conditions.

[0131] During normal operation, the theoretical value SW remains constant as long as the measured second pressure value D2 (and, if necessary, the first pressure value D1) does not necessitate a change in the theoretical value SW. The programming of the regulating device establishes criteria for determining when and how to change the theoretical value SW. Typically, the theoretical value SW remains constant as long as the second pressure value D2 is within a predetermined range relative to the theoretical value SW (or the corresponding first pressure value D1); when the second pressure value D2 deviates from the predetermined range, the theoretical value SW is gradually changed (see [link to relevant documentation] for more details). Figure 9 ).

[0132] Alternatively, it is possible to program the gradual conversion of the helium tank pressure or theoretical value SW to the target value ZW in the regulating device, where the target value ZW is determined by a second pressure value D2. For example, a corresponding second pressure value D2 can be selected, here atmospheric pressure is used as the target value, to prepare for opening the helium tank to the atmosphere, so that liquid helium can be refilled into helium tank 2 (see more on this). Figure 7 and Figure 8).

[0133] exist Figure 1 In this implementation, the regulating valve 5 is designed to be fully open in the event of a power outage. This ensures that no dangerous pressure will form in the helium tank 2. The helium flow when the regulating valve 5 is fully open is limited by a throttle 8 in the helium line 3.

[0134] Figure 2 A second embodiment of the device 1 according to the invention is schematically shown for regulating the pressure in the helium tank 2. Figure 2 The implementation form largely corresponds to Figure 1 The implementation form, thus explaining only the important differences.

[0135] exist Figure 2 In device 1, the helium line 3 further includes a flow sensor 14, which measures the current flow of helium through the helium line 3 or the regulating valve 5. The corresponding helium flow rate is read by the regulating device. The flow sensor 14 is located downstream of the regulating valve 5 in the helium line 3 along the flow direction.

[0136] The regulating device can use the helium flow rate value to control the correct operating status of device 1 or the entire associated cryostat (for reference) Figure 6 Here, the regulating device typically checks for different alarm conditions. In particular, it can be used to check for dangerous icing of the cryostat (see also...). Figure 10 ).

[0137] The flow sensor 14 typically determines the current volume of helium flowing per unit time (dV / dt); a turbine flow meter can be used for this purpose. However, it is also possible to use the flow sensor to determine the current mass of helium flowing per unit time (dm / dt), for example, using a Coriolis mass flow meter or a thermal mass flow meter.

[0138] Figure 3 A third embodiment of the device according to the invention is shown, which largely corresponds to Figure 2 The implementation methods. Therefore, only the important differences will be explained.

[0139] exist Figure 3In this embodiment, a second pressure sensor 7a is provided, which measures the pressure difference between the pressure in the helium tank 2 and the pressure in the helium recovery system 4 (here, at its input). Thus (and utilizing the knowledge of the first pressure value D1), a second pressure outside the helium tank 2, here in the helium recovery system 4, is indirectly measured. The corresponding second pressure value D2 of the pressure in the helium recovery system 4 is evaluated by the regulating device, wherein a predetermined theoretical value SW is determined by means of the second pressure value D2, and said theoretical value is used to adjust the regulating valve 5.

[0140] It should be noted that the pressure in helium recovery system 4 is typically slightly, usually up to 5 millibars, above atmospheric pressure.

[0141] Figure 4 A fourth embodiment of the device according to the invention is shown, which largely corresponds to Figure 2 The implementation methods. Therefore, only the important differences will be explained.

[0142] In this embodiment, a second pressure sensor 7 is provided, which measures the pressure difference (atm) between the helium tank 2 and the surrounding atmosphere, thereby indirectly measuring the atmospheric pressure (using the first pressure value D1). The second pressure value D2 (also denoted as DAT) of the measured atmospheric pressure is transferred to the regulating device. On the other hand, a third pressure sensor 9 is provided, which measures the pressure difference between the helium tank 2 and the helium recovery system 4 (here, at its input), thereby indirectly measuring the pressure in the helium recovery system 4 (using the first pressure value D1). The third pressure value D3 (also denoted as DHR) of the pressure in the helium recovery system 4 is also transferred to the regulating device.

[0143] The predetermined theoretical value can be determined using the second pressure value D2. Different alarm states are checked using the first pressure value D1, the second pressure value D2, the third pressure value D3, and the helium flow rate value. Using these alarm states, the compliant operation of device 1 or the entire cryogenic thermostat can be monitored by means of an electronic control device. In particular, faults in the helium recovery system 4 can be identified by comparing the second pressure value D2 (=DAT) and the third pressure value D3 (=DHR). For example, a failed compressor in the helium recovery system 4 causes the pressure DHR to exceed the pressure DAT by more than a predetermined threshold SWW, where SWW is, for example, selected as 10 mbar.

[0144] Figure 5 A fifth embodiment of the device according to the invention is shown, which largely corresponds to Figure 4 The implementation methods. Therefore, only the important differences will be explained.

[0145] exist Figure 5In this embodiment, an additional pipeline segment 10 is provided, which is connected in parallel to the helium pipeline 3 leading from the helium tank 2 to the helium recovery system 4. The additional pipeline segment 10 includes a shut-off valve 11 and a throttle valve 12. The shut-off valve 11 is kept closed during normal operation by an electric actuator (not shown), thereby blocking the additional pipeline segment 10, and the helium flow can only pass through the helium pipeline 3.

[0146] The regulating valve 5 in helium line 3 is configured such that it is closed in the event of a power failure, thus blocking helium line 3. Conversely, the shut-off valve 11 is configured to be open in the event of a power failure (the electric actuator can no longer keep shut-off valve 11 closed during a power outage; instead, shut-off valve 11 is typically opened by spring force). Thus, during a power outage, helium can flow from helium tank 2 to helium recovery system 4 through additional pipeline section 10; the helium flow is limited here by a throttle 12 in additional pipeline section 10. This prevents dangerous pressure buildup in helium tank 2 during a power outage.

[0147] Figure 6 An exemplary embodiment of an NMR measuring device 20 according to the present invention is illustrated, wherein the NMR measuring device includes an exemplary embodiment of a cryostat arrangement structure 21 according to the present invention.

[0148] The cryogenic thermostat arrangement 21 includes, on one hand, a vacuum-sealed container 22 (also called a vacuum tank), in which a helium tank 2 is disposed; that is, the helium tank 2 is vacuum-isolated. The helium tank 2 is partially filled with liquid helium and partially filled with gaseous helium (helium not shown further), and further includes a superconducting NMR magnet 23 cooled by the liquid helium.

[0149] On the other hand, the cryostat arrangement 21 has a device 1 for regulating the pressure in the helium tank 2, said device being substantially as described in... Figure 5 The configuration is shown here. An electronic control unit 13 is also shown here, which obtains measurements from pressure sensors 6, 7, and 9 and flow meter 14, and can also control and read the position of control valve 5. The control unit further has a storage device 17, in which it stores the measurement data obtained and the control data generated for the last 30 days. The electronic control unit 13 is also connected to an alarm device 15, which has an audible and optical signal generator 16, used to announce identified alarm conditions.

[0150] The helium tank 2 is connected to the device 1, or more precisely, to the middle section 26 of the helium line 3 extending within the device 1, via a neck tube 24 and the preceding section 25 of the helium line 3. Correspondingly, a first pressure sensor 6 can measure the pressure within the helium tank 2.

[0151] The cryostat arrangement 21 also includes a helium recovery system 4, which is connected to section 27 downstream of the helium line 3. The helium recovery system 4 includes a balloon reservoir 28 in which helium is initially collected. The balloon reservoir 28 receives atmospheric pressure from the outside and expands slightly during operation by the inflow of helium overcoming atmospheric pressure, thus maintaining a pressure slightly above atmospheric pressure inside the balloon reservoir 28. A compressor 29 is connected to the output of the balloon reservoir 28, which compresses the helium from the balloon reservoir (to, for example, up to 200 bar) and stores the compressed helium in a compressed gas cylinder 30.

[0152] In addition to the cryostat arrangement 21, the NMR measurement system 20 includes a superconducting NMR magnet 23 in a helium tank 2, and an NMR sample head 31 that extends into a vacuum tank 22 or a room temperature port 22a of a vacuum-isolated helium tank 2. Furthermore, an NMR spectrometer control device 32 is also part of the NMR measurement arrangement 20, which controls the NMR measurement using the NMR sample head 31. The NMR measurement can be performed on a sample placed in a sample volume 33 in the region at the outer end of the NMR sample head 31, typically introduced from above into the room temperature port 22 via a sample delivery system (not shown). The NMR spectrometer control device 32 also receives information about the regulation status of the helium tank pressure from an electronic adjustment device 13.

[0153] Figure 7 In one example, a flowchart illustrating a first variation of the method according to the invention for controlling the pressure in a helium tank is provided. Time is recorded to the right using exemplary moments. The measured pressures (for the dashed curve 71, the pressure in the helium tank, i.e., the first pressure value D1; and further, for the solid curve 72, the measured atmospheric pressure, i.e., the second pressure value D2) and the measured helium flow rate (helium flow rate value, dotted curve 73) are recorded upwards. In this variation, the helium tank should be opened to atmospheric pressure for refilling liquid helium, and the helium tank pressure should correspondingly change / decrease. Note that... Figure 7 It was obtained using experimental measurements.

[0154] Brief Overview

[0155] Normal operation on the helium tank is conducted during the time interval from 7:00 to approximately 11:00 prior to the start of descent, during which NMR measurements, for example, may occur. The theoretical pressure for the helium tank is set to 985 mbar, and the helium tank pressure measured by curve 71 is very accurately at 985 mbar. The atmospheric pressure measured by curve 72 fluctuates slightly here around a value of approximately 965 mbar. The slight overpressure in the helium tank prevents the inhalation of contaminants (especially humid air). During this normal operation, a relatively small, roughly constant flow of helium equivalent at approximately 10 ml / h is discharged through a regulating valve; the cooling power associated with the evaporation of this amount of helium compensates for the heat load on the cryostat.

[0156] At 11:00, the pressure drop in the helium tank now begins. This drop is programmed such that the theoretical helium tank pressure decreases at a constant rate (i.e., a linear ramp) from the theoretical value of 985 mbar to the target atmospheric pressure at approximately 3.66 mbar / h. The rate of decrease and the regulating loop are generally designed so that the helium tank pressure, or the first pressure value D1, on curve 71 follows the theoretical value of the linear drop with considerable accuracy (immediately). To further reduce the helium tank pressure according to the programmed theoretical value change curve, the electronic regulator opens the regulating valve significantly further than during normal operation, and the helium flow rate is significantly increased, up to 80 ml / h liquid equivalent. Note that during the drop, the atmospheric pressure decreases slightly, as can be seen from curve 72, dropping to approximately 962 mbar around 17:00.

[0157] Shortly after 5:00 PM, the programmed theoretical value reached atmospheric pressure, and the regulating device switched the regulating valve to a less open position. However, based on the temperature gradient within the liquid helium in the helium tank, the evaporation rate continued to increase for some time, and in order to maintain the pressure in the helium tank roughly at the theoretical value (which, shortly after 5:00 PM, essentially corresponded to atmospheric pressure), helium had to be allowed to flow out through the corresponding valve position via the regulating valve. Around 8:00 PM, the temperature gradient in the helium tank had been compensated for, and the helium flow rate again reached a constant low value, now slightly below 10 ml / h of liquid equivalent.

[0158] In the desired state, the helium tank can be opened to the atmosphere without the energy-disadvantageous sudden evaporation of a large amount of liquid helium.

[0159] Detailed explanation

[0160] A significant advantage derived from the use of two pressure sensors according to the invention is that the pressure in the helium tank (the first pressure) is automatically and can be matched with a second pressure (e.g., atmospheric pressure or pressure in the helium recovery system) at user-determined time intervals. This is desirable, for example, before helium transfer. For helium transfer, an opening providing access to the helium tank must be opened so that a transfer line can be introduced. Here, helium typically escapes from the helium tank so rapidly that the tank is depressurized to atmospheric pressure. This rapid pressure change poses a certain danger to the magnet (there is a possibility of magnet quenching), and on the other hand, the pressure change is thermodynamically inefficient because the enthalpy of the cold helium remains unused during the rapid outflow.

[0161] Within the scope of this invention, the pressure in the helium tank can be decreased slowly and with precise targeting; in particular, pressure reduction can begin the day before a planned helium transfer. This is more energy-efficient than a "sudden" pressure release. Figure 7 The diagram illustrates an example of pressure reduction over a predetermined 6-hour duration. The solid line (curve 72) represents atmospheric pressure, the dashed line (curve 71) represents the pressure in the helium tank, and the dotted line (curve 73) represents the helium flow rate.

[0162] As can be seen from curve 73, the helium flow initially increases only slowly after the pressure drop begins around 11:00, then increases further during the subsequent pressure drop (although the pressure drop is linear), and then continues to increase for several hours after the pressure drop ends around 17:00.

[0163] The pressure and temperature of boiling helium in a helium tank are correlated via a vapor pressure curve. This, of course, only applies to liquids on a surface, because helium has relatively poor thermal conductivity. A temporary temperature gradient is formed within liquid helium as pressure changes occur.

[0164] When the pressure drops rapidly in the helium tank as illustrated in the example above, the temperature of the liquid helium on the surface decreases, while the liquid helium below the surface remains hot and cools only slowly to the surface temperature. During this time, more liquid helium evaporates than would be expected from the heat load on the helium tank, because energy must be extracted from the helium below the surface for cooling. This cooling power is provided by the increased evaporation. After the pressure reduction is complete, the helium below the surface is typically not yet in thermal equilibrium with the surface, and the evaporation rate (or the measured helium flow rate) also increases for some time after the pressure reduction has ended.

[0165] The effect is strongly time-dependent – ​​the faster the pressure reduction is implemented, the more pronounced the effect, because less time is available for the liquid volume to approach thermal equilibrium.

[0166] It is particularly advantageous to maintain a constant helium flow rate as much as possible during the pressure reduction, because this allows for optimized utilization of the enthalpy of the cold gas. Therefore, it is advantageous to initially reduce the pressure more rapidly during the pressure drop in the helium tank (to artificially accelerate the initial evaporation) and then reduce the pressure more slowly near the end of the pressure reduction phase (to keep the evaporation rate constant). This can be achieved using the device design according to the invention. Figure 8 This illustration shows a second variation of the method according to the invention for pressure regulation in a helium tank.

[0167] Figure 8 The graph records time to the right (in any unit) and pressure (first pressure in the helium tank / first pressure value D1 in curve 81, and atmospheric pressure / second pressure value D2 in curve 82) and helium flow rate through the regulating valve (curve 83, helium flow rate value) to the up.

[0168] Before time t1, normal operation still dominates, and the theoretical value of the helium tank pressure is 1000 mbar, with the first pressure value D1 on curve 81 corresponding to a constant value at this theoretical value. The atmospheric pressure on curve 82 is 970 mbar; the atmospheric pressure remains constant here throughout the observation time interval. The helium flow rate is initially at a low liquid equivalent of 15 ml / h.

[0169] Starting at time t1 and decreasing the time interval to time t2, the theoretical value of the helium tank pressure decreases to atmospheric pressure via a non-linear ramp; the first pressure value D1 on curve 81 immediately follows the adjusted theoretical value. At the beginning of the decreasing time interval, the pressure decrease per unit time is relatively large, and then always decreases further until the end of the decreasing time interval. By correspondingly selecting the process of change of the theoretical value, it can be achieved that the helium flow rate remains approximately constant throughout the decreasing time interval from t1 to t2, maintained at approximately 30 ml / h liquid equivalent in the example shown, as can be seen in curve 83. At time t2, the regulating valve can be closed again in this manner, thereby resetting a lower helium flow rate of 15 ml / h liquid equivalent.

[0170] The theoretical value decreases gradually and linearly. Figure 7 This method has achieved a significant improvement in energy efficiency compared to the sudden pressure drop when opening a helium tank, and utilizes theoretical values ​​with non-linear reduction... Figure 8 This approach can also further improve energy efficiency.

[0171] Figure 9Shows a third variant of the method according to the invention for regulating the pressure in a helium tank. The graph records time (in arbitrary units) to the right and pressure upwards (with curve 91 representing the first pressure / helium tank pressure with a first pressure value D1, which curve corresponds with good precision to the curve 93 of the theoretical value of the pressure in the helium tank, and furthermore with curve 92 representing the second pressure / atmospheric pressure with a second pressure value D2).

[0172] In the scope of the third variant, the helium tank pressure is stabilized for the normal operation of the NMR magnet in order to minimize measurement artifacts during NMR measurements and at the same time taking into account weather conditions, thus achieving a high operational safety. The electronic regulating device determines the theoretical value of the helium tank pressure for this purpose and in particular also performs a change for the theoretical value of the helium tank pressure, wherein the electronic regulating device evaluates the second pressure, here the atmospheric pressure.

[0173] In the scope of normal operation, the helium tank pressure should remain constant during NMR measurements because pressure fluctuations can trigger dimensional changes in the measurement system, which dimensional changes can, for example, change the sample position relative to the magnet or deform the magnet itself. Correspondingly, the theoretical value of the helium tank pressure (reference curve 93) remains at a constant value most of the time, here in the time intervals from t1 to t2, t3 to t4, t5 to t6 and from t7 onwards; the helium tank pressure (reference curve 91) follows the theoretical value quite precisely / immediately. During these time intervals, NMR measurements can be carried out under stable measurement conditions. <{

[0174] Furthermore, the helium tank pressure (reference curve 91) should always be significantly above the atmospheric pressure (reference curve 92) in order to prevent pollutants (such as moist air) from being sucked into the helium tank. When the atmospheric pressure rises, it approaches the helium tank pressure or the theoretical value further. In the illustrated example, it is set to check the current difference DIF between the helium tank pressure (with pressure value D1) and the atmospheric pressure (with pressure value D2) and compare it with a lift threshold HSW. Using DIF = D1 - D2, it is checked whether DIF < HSW already exists. If so, the theoretical value (reference curve 93) is increased by one step, where one step is 20 mbar here. The current DIF is less than HSW at time t2, and the hitherto theoretical value of 980 mbar before t2 is increased to a new theoretical value of 1000 mbar starting from t3. Between t2 and t3, the theoretical value (curve 93) is increased with a here linear lift curve so that the helium tank pressure (curve 91) can follow this change well / immediately. Starting from time t3, the theoretical value and the helium tank pressure then remain constant again, here until t4, despite different fluctuations in curve 92.

[0175] Furthermore, it must be ensured that the overpressure in the helium container is not excessive relative to the surrounding atmosphere. The helium container must never explode due to overpressure. To ensure this, the helium container has an overpressure valve that opens from a certain differential and releases helium, and as another safety feature, a rupture disc is present through which a large amount of helium can also escape from the container, especially in the event of a quench. However, the triggering of the safety device should only be used for unforeseen emergencies. In the illustrated example, this is therefore further set up to check the current difference DIF between the helium container pressure (with pressure value D1) and atmospheric pressure (with pressure value D2) and compare it to the reduction threshold SSW. Using DIF = D1 - D2, it is checked whether DIF > SSW already exists. If so, the theoretical value (reference curve 93) decreases in stages, where stage one here is also 20 mbar. The current DIF is greater than SSW at t4, and the theoretical value up to 1000 mbar before t4 decreases from t5 to a new theoretical value of 980 mbar. Between t4 and t5, the theoretical value (curve 93) decreases linearly, so the helium tank pressure (curve 91) follows this change well / immediately. From time t5 onwards, the theoretical value and helium tank pressure remain constant again until t6. Furthermore, at this point, DIF is again greater than SSW at t6, and the theoretical value of 980 mbar prior to t4 decreases to a new theoretical value of 960 mbar starting at t7. Between t6 and t7, the theoretical value (curve 93) decreases linearly, so the helium tank pressure (curve 91) follows this change well / immediately. From time t7 onwards, the theoretical value and helium tank pressure remain constant again.

[0176] During the corresponding time periods of theoretical value variation, i.e. from t2 to t3, further from t4 to t5, and further from t6 to t7, NMR measurements are not performed due to unstable pressure conditions (variable pressure) in the helium tank. The electronic conditioning device reports continuous theoretical value variations or pressure instability to the NMR spectrometer control device, which sets a measurement pause for these times.

[0177] Figure 10 The schematic flowchart illustrates an exemplary monitoring of the correct operation of the device according to the invention, used for regulating pressure in the helium tank or the associated NMR measurement setup, by means of an alarm for monitoring icing conditions of a cryostat. Other alarm conditions can be monitored in a similar manner. The device, for example, is used in… Figure 5 The configuration shown, or the NMR measurement arrangement structure, is as described in Figure 6 The structure shown in the figure.

[0178] After monitoring begins for 100 seconds, the current helium flow rate is measured using a flow meter. The read helium flow rate is then compared to a zero helium flow rate for 300 seconds. If the measured helium flow rate is greater than zero, the helium flow rate is remeasured (within the scope of continuous monitoring) and this process continues.

[0179] If the measured helium flow rate is zero, the position of the regulating valve 400, controlled by the regulating device, is determined. This controlled position is then compared to the (fully) closed position 500. When the regulating valve is in the (fully) closed position, it can be concluded that, according to the regulating device's programming, the pressure in the helium tank should currently be increased, and therefore the regulating valve is closed as planned and should precisely block the helium flow; the monitoring then continues (within the scope of continuous monitoring) with the next measurement of the helium flow rate value 200.

[0180] If the control valve is not in the (fully) closed position, it is necessary to determine if there is an undesirable and dangerous blockage of helium flow through the cryostat or the helium pipeline leading from the helium tank, due to icing. In this case, alarm message 600 will be output. Based on alarm message 600, manual or automatic countermeasures or safety measures can then be taken.

[0181] List of reference numerals

[0182] 1 device

[0183] 2 helium tanks

[0184] 3. Helium pipeline leading from the helium tank

[0185] 4 Helium recovery system

[0186] 5. Control valve

[0187] 6. First pressure sensor (for helium tank pressure)

[0188] 7. Second pressure sensor (here: differential pressure gauge, for atmospheric pressure)

[0189] 7a Second pressure sensor (here: differential pressure gauge, used for pressure in helium recovery systems)

[0190] 8 throttles (in helium line 3)

[0191] 9. Third pressure sensor (here: differential pressure gauge, used for pressure in helium recovery systems)

[0192] 10 Another pipeline segment

[0193] 11 Stop valve

[0194] 12 throttle valves (in another pipeline segment 10)

[0195] 13 Electronic control devices

[0196] 14 Flow Sensors

[0197] 15 alarm devices

[0198] 16 Sound and optical signal generators

[0199] 17 storage devices

[0200] 20NMR measurement setup

[0201] 21. Low-Temperature Thermostat Arrangement Structure

[0202] 22 Vacuum-evacuated containers / vacuum tanks

[0203] 22a room temperature orifice

[0204] 23 Superconducting NMR Magnet

[0205] 24 neck tube

[0206] The section preceding the 25 helium pipeline

[0207] 26. The middle section of the helium pipeline in the device

[0208] Section following the 27 helium pipeline

[0209] 28 balloon storage device

[0210] 29 compressors

[0211] 30 compressed gas cylinders

[0212] 31NMR sample head

[0213] 32NMR Spectrometer Control Device

[0214] 33 Sample Volume

[0215] 71 First pressure value curve (helium tank pressure)

[0216] 72 Second pressure value curve (atmospheric pressure)

[0217] 73 Helium flow rate curve

[0218] 81 First pressure value curve (helium tank pressure)

[0219] 82 Second pressure value curve (atmospheric pressure)

[0220] 83 Helium flow rate curve

[0221] 91 First pressure value curve (helium tank pressure)

[0222] 92 Second pressure value curve (atmospheric pressure)

[0223] 93 Theoretical value curve for helium tank pressure

[0224] Starting from 100

[0225] 200 Measurement of helium flow rate

[0226] 300 compares the helium flow rate value with zero.

[0227] 400 determines the operating position of the control valve.

[0228] 500 compares the controlled position of the regulating valve with the (fully) closed position.

[0229] 600 alert message

[0230] atm atmosphere

[0231] D1 First Pressure Value (Helium Tank Pressure)

[0232] D2 is the second pressure value (usually atmospheric pressure here).

[0233] D3 Third Pressure Value

[0234] The difference between the first and second pressure values ​​of DIF

[0235] DIF=D1-D2

[0236] HSW raises threshold

[0237] SSW reduces threshold

[0238] t1-t7 time periods

Claims

1. A device (1) for regulating the pressure in a helium tank (2) of an NMR magnet (23), said device comprising: - A first pressure sensor (6) for measuring the first pressure in the helium tank (2). - A regulating valve (5) for adjusting the flow of helium gas from the helium tank (2). - An electronic regulating device (13) for controlling the regulating valve (5). The electronic adjustment device (13) is designed for, - Obtain the first pressure value D1 measured by the first pressure sensor (6), - and adjusts the position of the regulating valve (5) based on the measured first pressure value D1, wherein the first pressure value D1 is adjusted to a predetermined theoretical value SW, The device (1) further includes -At least one second pressure sensor (7; 7a) for measuring a second pressure outside the helium tank (2). Furthermore, the electronic regulating device (13) is also designed for, - Obtain the second pressure value D2 measured by the second pressure sensor (7; 7a). - and the theoretical value SW is determined based on the second pressure value D2. Furthermore, the regulating device (13) is designed to gradually change the theoretical value SW of the pressure in the helium tank (2) once the difference DIF=D1-D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds a predetermined threshold.

2. The device according to claim 1, characterized in that, The adjustment device is designed such that when the difference DIF is less than or equal to the rise threshold HSW, the theoretical value SW increases in one step, and when the difference DIF is greater than or equal to the decrease threshold SSW, the theoretical value SW decreases in one step, wherein HSW <SSW。 3. The device according to claim 1 or 2, characterized in that, The regulating device is designed such that the corresponding level is selected in the range of 5-25 mbar, and the theoretical value SW is changed at the level once the difference DIF=D1-D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds a predetermined threshold.

4. The device (1) according to any one of claims 1 to 3, characterized in that, The second pressure is the pressure in the surrounding atmosphere (atm).

5. The device (1) according to any one of claims 1 to 3, characterized in that, The second pressure is the pressure in the helium recovery system (4).

6. The device (1) according to any one of claims 1 to 3, characterized in that, The device (1) further includes: - A third pressure sensor (9) for measuring a third pressure outside the helium tank (2). The second and third pressures include the pressure in the surrounding atmosphere (atm) and the pressure in the helium recovery system (4).

7. The device (1) according to any one of the preceding claims, characterized in that, The device (1) further includes: - A flow sensor (14) for measuring the helium flow rate of the helium gas flowing out of the helium tank (2).

8. The device (1) according to any one of the preceding claims, characterized in that, The adjustment device (13) includes a storage device (17) or a connector for the storage device (17), which records sensor values ​​obtained by the adjustment device (13).

9. The device (1) according to any one of the preceding claims, characterized in that, The regulating device (13) is designed to convert a theoretical value SW for the pressure in the helium tank (2) to a target value ZW over a predetermined duration, wherein the target value ZW depends on a second pressure value D2, and in particular, the duration can be selected by the user.

10. The device (1) according to claim 9, characterized in that, The target value ZW corresponds to the second pressure value D2, i.e., ZW=D2, or the target value ZW is above the second pressure value D2 with a small pressure addition DA, i.e., ZW=D2+DA and DA≤3 mbar.

11. The device (1) according to claim 9 or 10, characterized in that, The adjustment device (13) is designed to linearly convert the theoretical value SW to the target value ZW over time.

12. The device (1) according to claim 9 or 10, characterized in that, The regulating device (13) is designed to make the theoretical value SW change non-linearly over time, wherein the helium flow rate through the regulating valve (5) remains approximately constant during the duration during which the theoretical value SW transitions to the target value ZW.

13. The device (1) according to claim 12, characterized in that, The adjustment device (13) is designed to cause the theoretical value SW to decrease more rapidly at the start of the transition than near the end of the transition when the theoretical value SW transitions to the target value ZW.

14. The device (1) according to any one of the preceding claims, characterized in that, The device (1) further includes an alarm device (15) which automatically triggers (600) an alarm message in one or more predetermined alarm situations, and in particular the alarm device (15) includes a sound signal generator (16) and / or an optical signal generator (16) and / or a radio signal generator and / or a data signal generator.

15. The device (1) according to claim 14 and any one of claim 4 or 6, characterized in that, The alarm conditions include: the pressure value D1 of the helium tank pressure (2) drops below the pressure value D2 of the atmospheric pressure.

16. The device (1) according to claim 14 or 15, characterized in that, The alarm conditions include: the pressure value D1 of the helium tank exceeds a predetermined maximum helium tank pressure; in particular, the first alarm condition regarding D1 includes: the pressure value D1 of the helium tank exceeds a predetermined first maximum helium tank pressure EHM; the second alarm condition regarding D1 includes: the pressure value D1 of the helium tank exceeds a predetermined second maximum helium tank pressure ZHM, and ZHM>EHM; and the alarm message is different for the first alarm condition and the second alarm condition regarding D1.

17. The device (1) according to any one of claims 14 to 16 and according to claim 7, characterized in that, Alarm situations include: the measured helium flow rate exceeds the predetermined maximum helium flow rate.

18. The device (1) according to claim 17, characterized in that, The predetermined maximum helium flow rate depends on current or recent changes in the helium tank pressure, especially the maximum helium flow rate is higher during and / or immediately after a reduction in the helium tank pressure than when the helium tank pressure is under constant control.

19. The device (1) according to any one of claims 14 to 18 and according to claim 7, characterized in that, Alarm conditions include: the measured helium flow rate is lower than the predetermined minimum helium flow rate.

20. The device (1) according to claim 19, characterized in that, The predetermined minimum helium flow rate depends on current or recent changes in the helium tank pressure, especially when the minimum helium flow rate is lower during and / or immediately after an increase in the helium tank pressure than when the helium tank pressure is kept constant.

21. The device (1) according to any one of claims 14 to 20 and according to claim 7, characterized in that, Alarm conditions include: the measured helium flow rate is zero and the current position of the regulating valve (5) or the position of the regulating valve (5) currently controlled by the regulating device (13) is not closed.

22. The device (1) according to any one of claims 14 to 21 and according to claim 7 and any one of claims 5 or 6, characterized in that, Alarm conditions include: the measured helium flow rate is zero and the pressure value D2 in the helium recovery system (4) rises until the pressure value D1 in the helium tank (2).

23. The device (1) according to any one of claims 14 to 22 and claim 6, characterized in that, Alarm conditions include: the difference between the pressure value DHR measured in the helium recovery system (4) and the pressure value DAT measured in the ambient atmosphere (atm), DHA = DHR - DAT, exceeds a predetermined threshold SWW, especially when SWW is selected in the range of 2.5 mbar to 20 mbar.

24. The device (1) according to any one of claims 14 to 23, characterized in that, At least a portion of the alarm conditions includes the current position of the regulating valve (5) or the current position of the regulating valve (5) controlled by the regulating device (13).

25. A method for adjusting the pressure in a helium container (2) of an NMR magnet (23), wherein, The first pressure in the helium tank (2) is measured using a first pressure sensor (6), wherein the flow of helium gas from the helium tank (2) is regulated using a regulating valve (5). The electronic regulating device (13) controls the regulating valve (5). And the electronic adjustment device (13) - Obtain the first pressure value D1 measured by the first pressure sensor (6), - And the position of the regulating valve (5) is adjusted based on the measured first pressure value D1, so that the first pressure value D1 is adjusted to the predetermined theoretical value SW. The second pressure outside the helium tank (2) is measured using at least one second pressure sensor (7; 7a). In addition, the electronic adjustment device (13) - Obtain the second pressure value D2 measured by the second pressure sensor (7; 7a). - and the theoretical value SW is determined based on the measured second pressure value D2. And once the difference DIF = D1 - D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds a predetermined threshold, the regulating device (13) gradually changes the theoretical value SW used for the pressure in the helium tank (2). The method is particularly effective when using the device (1) according to any one of the preceding claims.

26. The method according to claim 25, characterized in that, When the difference DIF is less than or equal to the rise threshold HSW, the theoretical value SW increases by one level, and when the difference DIF is greater than or equal to the decrease threshold SSW, the theoretical value decreases by one level, where HSW <SSW, The method is particularly effective when using the device (1) according to claim 1.

27. The method according to claim 25 or 26, characterized in that, Select the appropriate level within the range of 5-25 mbar, and change the theoretical value SW at the level once the difference DIF=D1-D2 between the measured first pressure value D1 and the measured second pressure value D2 reaches or exceeds a predetermined threshold.

28. The method according to any one of claims 25 to 27, characterized in that, The regulating device (13) converts the theoretical value SW for the pressure in the helium tank (2) to a target value ZW over a predetermined duration, wherein the target value ZW depends on a second pressure value D2, and in particular the duration can be selected by the user, especially when the method is implemented using the device (1) according to claim 9.

29. The method according to claim 28, characterized in that, The regulating device (13) changes the theoretical value SW nonlinearly over time, wherein the helium flow rate through the regulating valve (5) is kept approximately constant during the duration during which the theoretical value SW transitions to the target value ZW, especially when the method is implemented using the device (1) according to claim 12.

30. The method according to any one of claims 25 to 29, characterized in that, Using an alarm device (15), an alarm message is automatically triggered (600) in one or more predetermined alarm situations, wherein the alarm device (15) includes a sound signal generator (16) and / or an optical signal generator (16) and / or a radio signal generator and / or a data signal generator. The alarm conditions include: the measured helium flow rate of the helium gas flowing from the helium tank (2) through the regulating valve (59) is zero and at the same time the current position of the regulating valve (5) or the position of the regulating valve (5) currently controlled by the regulating device (13) is not closed, especially when the method is implemented using the device (1) according to claim 21.

31. The arrangement structure of the low-temperature thermostat (21) includes: - Vacuum-isolated helium container (2). -The device (1) according to any one of claims 1 to 24; The first pressure sensor (6) is connected to the helium tank (2), and the second pressure sensor (7; 7a) is connected to a location outside the helium tank (2), specifically the second pressure sensor (7; 7a) is connected to the surrounding atmosphere (atm) or to the helium recovery system (4). Furthermore, the regulating valve (5) is located in the helium pipeline (3) leading out from the helium tank (2).

32. The low-temperature thermostat arrangement structure (21) according to claim 31, characterized in that, The cryogenic thermostat arrangement (21) also has a helium recovery system (4) connected to the helium pipeline (3).

33. NMR measurement setup (20), including: - The low-temperature thermostat arrangement structure (21) according to claim 31 or 32. - The superconducting NMR magnet (23) in the helium tank (2) of the cryogenic thermostat arrangement (21). -NMR sample head (31), the NMR sample head extending into the room temperature port (22a) of the vacuum-isolated helium container (2), and -NMR spectrometer control device (32) for controlling NMR measurements using the NMR sample head (31).

34. The NMR measurement arrangement structure (20) according to claim 33 is used for performing NMR measurements. in, The electronic regulating device (13) transmits the state of the helium tank pressure regulation to the NMR spectrometer control device (32). Furthermore, during the period when the pressure in the helium tank (2) is unstable, the NMR spectrometer control device (32) suspends the NMR measurement.

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