Monitoring the performance of cryogenic pumps

Abstract

A method for monitoring the performance of a cryogenic pump (5), a circuit (14) for monitoring the performance, and the cryogenic pump (5) are disclosed. The method includes: after a regeneration cycle is completed, controlling the cryogenic pump (5) to execute a predetermined test routine to test the performance of the cryogenic pump (5) under predetermined conditions; monitoring the cryogenic pump during the predetermined test routine to collect data indicating the performance of the cryogenic pump (5); and storing the data collected during the monitoring.

Description

Technical Field

[0001] The field of this invention relates to cryogenic pumps and methods and circuits for monitoring the performance of cryogenic pumps. Background Technology

[0002] Cryogenic pumps work by condensing or trapping the gas to be pumped. This means that cryogenic pumps need to be regenerated periodically to remove the trapped gas. Regeneration involves isolating the pump from the vacuum system and heating the pump while introducing purge gas to dilute the trapped gas. The trapped gas is then desorbed or vaporized by heating.

[0003] If a cryogenic pump / system fails to meet its technical requirements and is slowly deteriorating without affecting the customer's process, it may unexpectedly fail. This is extremely costly for cryogenic pump users, especially if the cryogenic pump is used in processes such as those of integrated circuit manufacturers.

[0004] It is desirable to provide a method and / or diagnostic system capable of monitoring the current health or performance of a cryogenic pump, identifying pump degradation, and thus predicting future poor performance or failure. The ability to predict performance degradation allows maintenance engineers to intervene before degradation inappropriately affects the processes being pumped. Summary of the Invention

[0005] A first aspect provides a method for monitoring the performance of a cryogenic pump, the method comprising: after completing a regeneration cycle, controlling the cryogenic pump to execute a predetermined test routine to test the performance of the cryogenic pump under predetermined conditions; monitoring the cryogenic pump during the predetermined test routine to collect data indicating the performance of the cryogenic pump; and storing the data indicating the pump collected during the monitoring.

[0006] The cryogenic pump is periodically regenerated to remove accumulated condensate. This is done when the pump is not being used to pump the vacuum chamber, so that during regeneration, the pump is typically under the control of the control circuitry associated with the pump, rather than being actively used to pump process gases from the cryogenic vacuum chamber. Additionally, the gate valve leading to the vacuum chamber is closed.

[0007] Furthermore, once the regeneration cycle is complete, the pump's condition is known, and the gate valve leading to the vacuum chamber emptied by the pump is closed. This provides an ideal timeframe for performing test procedures, as the vacuum system emptied by the pump will be unaffected and the pump's condition is known. Therefore, the pump's behavior during the test procedures performed at this time will indicate its current performance, independent of the emptied vacuum system and any collected condensate. This means that any comparison of the current test with a previous test performed under nearly identical conditions will not only provide an accurate description of the pump's current health but also an indication of how that health or performance has changed over time. Additionally, since regeneration occurs periodically, this provides the opportunity to perform these tests regularly, and therefore, any deterioration of the pump can be monitored periodically.

[0008] In some embodiments, the method controls the cryogenic pump to periodically execute the predetermined test routine after at least a subset of the regeneration cycle.

[0009] To monitor pump degradation and predict pump failure before it occurs, it is preferable to perform any pump test routines periodically. Since the regeneration cycles are performed periodically, the test routines can be performed after a certain proportion of these regeneration cycles, possibly after each regeneration cycle or after an alternative regeneration cycle.

[0010] In some embodiments, the method includes an additional step of determining the performance of the pump from the collected data.

[0011] The collected data indicates the current performance of the pump, and the method can analyze the data to determine said performance.

[0012] In some embodiments, the step of determining the performance of the pump includes comparing data obtained from the current test routine with data obtained from a previous test routine.

[0013] The absolute value of the data obtained from the test routine indicates the current performance of the pump, and comparing this data with data from other earlier test results provides a valid indication of any changes in the pump's performance, and in fact provides the rate of change of the pump's performance, and therefore can help to provide a prediction of when the pump may fail.

[0014] In some embodiments, the method includes an additional step of outputting data indicating the performance of the pump.

[0015] The collected data can be output. It can be output as raw data or as processed data, and in some embodiments as an indicator of pump performance. The indicator can be accessible to the pump operator. The indicator can be in the form of a digital performance indicator or a color-coded indicator. In cases where performance is determined to be low, the indicator can indicate the need for input from a maintenance engineer. A pump performance indicator can be generated in response to the collected data values ​​and / or changes in the collected data values ​​when compared to data values ​​collected during previous testing. Changes in the collected values ​​indicate a deterioration in pump performance and provide a basis for predicting future pump performance, thereby allowing the pump to be replaced before failure or excessive degradation of its performance.

[0016] In some embodiments, the step of outputting the data includes: receiving a request for the data and outputting the data in response to the request.

[0017] The request can come from a maintenance engineer at the pump site, and the data can be output via a port on the pump, or it can be a request from a remote server, and the data can be output to the remote server via a network.

[0018] In some embodiments, the predetermined test routine includes determining the cooling level provided by the cryogenic pump at a predetermined motor speed.

[0019] A predetermined test procedure is a routine in which the pump is operated in a predetermined manner and its performance is measured. In some cases, the test procedure may include: the cryogenic pump operating at a constant predetermined motor speed, and the level of cooling provided by the cryogenic pump at this motor speed being measured. At this point, the cryogenic pump may have a variable-speed motor that pumps a refrigerant, such as helium, around the refrigeration system. The motor speed affects the rate at which the refrigerant is pumped around the system, and thus affects the cooling capacity that the system can provide. When the motor speed is set to a constant value, the cooling capacity at that speed indicates the current performance and effectiveness of the cryogenic pump. Therefore, operating the motor at a predetermined speed and determining how much cooling the cryogenic pump then provides is an indicator of the pump's performance.

[0020] In some embodiments, the step of controlling the cryogenic pump to perform a predetermined test routine includes: controlling a variable speed motor that controls the refrigerant flow through the refrigeration system of the cryogenic pump to operate at a predetermined speed; setting a first predetermined temperature for a first stage of the cooler and a second predetermined temperature for a second stage of the cooler; and controlling heaters associated with the first and second stages of the cooler to maintain the first and second predetermined temperatures; and the step of determining the performance of the cryogenic pump includes determining the power applied to the heaters to maintain the first and second predetermined temperatures.

[0021] One way to determine the level of cooling provided by the cryogenic pump is by setting predetermined temperatures for the first and second stages of the refrigerator, in some cases these predetermined temperatures may be selected as the normal operating temperatures of the cryogenic pump, and determining the power consumed by the heaters associated with these stages of the refrigerator to maintain these temperatures. The level of cooling provided by the cryogenic pump is a function of the power applied to the heaters. In this respect, as the performance of the cryogenic pump deteriorates over time, the cooling provided by the pump decreases, and the amount of power applied to the heaters to maintain the temperatures also decreases, indicating this deterioration in performance.

[0022] In some embodiments, the method includes an additional step of receiving input indicating at least one of the predetermined temperature and the predetermined motor speed, the method being configured to use the received predetermined temperature and motor speed to perform a subsequent test routine.

[0023] In some embodiments, a service engineer may be able to update the predetermined temperature and / or motor speed of the test, where it may be necessary to change the test conditions to reflect the current or future operating conditions of the cryogenic pump.

[0024] The second aspect provides a computer program including computer-readable instructions that, when executed by a processor, control the processor to perform steps in the method according to the first aspect.

[0025] The third aspect provides control and diagnostic circuitry for a cryogenic pump, the control circuitry being configured to determine when a regeneration cycle has been completed, and after the completion of the regeneration cycle, to control the cryogenic pump to execute a predetermined test routine for testing the performance of the cryogenic pump under predetermined conditions; and the diagnostic circuitry being configured to: monitor the performance of the cryogenic pump during the predetermined test routine; and to store data indicating the performance obtained from the monitoring.

[0026] In some embodiments, the control circuitry is configured to control the cryogenic pump to periodically execute the predetermined test routine after at least a subset of the regeneration cycle.

[0027] In some embodiments, the diagnostic circuit is configured to determine the performance of the pump based on the collected data.

[0028] In some embodiments, the diagnostic circuit is configured to determine the performance of the pump by comparing data obtained from the current test routine with data obtained from a previous test routine.

[0029] In some embodiments, the diagnostic circuit is configured to output data indicating the performance of the pump.

[0030] In some embodiments, the diagnostic circuit is configured to output the data in response to receiving a request for the data.

[0031] In some embodiments, the predetermined test routine includes determining the cooling level provided by the cryogenic pump at a predetermined motor speed.

[0032] In some embodiments, the control circuit is configured to control the cryogenic pump to perform the predetermined test routine by: controlling a variable speed motor that controls the refrigerant flow through the refrigeration system of the cryogenic pump to operate at a predetermined speed; setting a first predetermined temperature for a first stage of the cooler and a second predetermined temperature for a second stage of the cooler; controlling heaters associated with the first and second stages of the cooler to maintain the first and second predetermined temperatures; and the diagnostic circuit is configured to determine the power applied to the heaters to maintain the first and second predetermined temperatures.

[0033] A fourth aspect provides a cryogenic pump, the cryogenic pump comprising: a refrigerator unit; a variable speed motor for controlling the refrigerant flow through a cooling system of the cryogenic pump; and a control and diagnostic circuit according to a third aspect.

[0034] In some embodiments, the refrigerator unit includes a two-stage refrigerator; and the cryogenic pump further includes: a temperature sensor for monitoring the temperature of the first stage of the refrigerator and a temperature sensor for monitoring the temperature of the second stage of the refrigerator; and a heater for supplying heat to the first stage and a heater for supplying heat to the second stage of the refrigerator.

[0035] In some embodiments, the control circuitry is also configured to control the regeneration of the pump.

[0036] The regeneration cycle performed by the pump will be under the control of the control circuit associated with the pump, and the same control circuit can be used to control the execution of the test routine.

[0037] Further specific and preferred aspects are set forth in the appended independent and dependent claims. Features of the dependent claims may be appropriately combined with features of the independent claims, and may be combined in combinations other than those expressly set forth in the claims.

[0038] When a device feature is described as operable to provide a function, it will be understood that this includes device features that provide that function or are adapted or configured to provide that function. Attached Figure Description

[0039] Embodiments of the invention will now be described further with reference to the accompanying drawings, in which:

[0040] Figure 1 A cryogenic pump according to an embodiment is shown, along with control and diagnostic circuitry; and

[0041] Figure 2 A flowchart illustrating the steps in a method according to an embodiment is shown. Detailed Implementation

[0042] Before discussing any embodiments in more detail, an overview will be provided first.

[0043] The embodiment provides software-based functionality that helps determine the pump's performance capabilities in a customer's operating environment. This software-based functionality controls the pump to perform diagnostic tests after a regeneration cycle, and information collected during periodic diagnostic tests can be obtained by a service engineer to help determine the pump's current cooling capacity.

[0044] In some embodiments, the cryogenic pump includes a variable speed motor and is configured to operate at several operating RPMs including 72 rpm and at first and second stage temperatures including several operating temperatures including 65 K and 13.5 K. During a test routine, the pump can be controlled to operate under these fixed operating conditions (the first and second stage temperatures are typically 65 K and 13.5 K, and the motor is at 72 RPM), and the resulting amount of heater power applied to the heater will be measured as a maximum amount or a percentage of actual watts. These power measurements are indicators of available cooling capacity and therefore indicators of the cryogenic pump's performance.

[0045] In some embodiments, a test routine will be used to test the new pump, and the results will be compared with those of subsequent test routines performed after each regeneration on the customer's tool. The results from the production test and the first regeneration will be used as a baseline to monitor pump performance after each cooling cycle, thereby maintaining a trend line in performance.

[0046] The cryogenic pump will be regenerated in the usual manner, and then during the “cooling” phase of the set routine, it can be “health-checked” by executing a test routine.

[0047] This process can be performed by applying a heat load, calculated in watts, by the module to maintain a predetermined temperature at the set rpm of the motor / regenerator, for example, 65K for the first stage and 13.5K for the second stage.

[0048] In some embodiments, the control circuitry will also provide an option to allow maintenance engineers to run diagnostic health checks using parameters of their choice by sending special commands to the module.

[0049] Regeneration is a process of heating the surface of the cryogenic plate using electric heaters located on the first and second stages. N2 gas is used to dilute H2 gas, which is then pumped into the activated carbon in the second stage of the implant pump. The cryogenic pump stages are then cleaned using a coarse / purge process at elevated temperatures (e.g., 310 K, and in some cases up to 330 K) to release the trapped gas from the pressure reducing valve to the gas scrubber.

[0050] The cryogenic pump is then cooled to a set temperature (290K in one example) and evacuated to a set vacuum (e.g., ~50 micrometers). To check the effectiveness of the evacuation, a rise rate test (ROR) is performed until it has passed a predetermined value, for example, 10 micrometers per minute.

[0051] After the ROR is passed, the motor is started and the cryogenic pump is cooled to the base temperature (in some examples, such as implantable pumps, the base temperature is 65K / 13.5K), and after performing a health check, the cryogenic pump is ready for user use and the cryogenic pump is "regeneration complete".

[0052] In some embodiments, cryogenic pumps use a variable speed of a motor, at any speed between 30 and 144 rpm, to drive a regenerator within a cylinder to utilize helium expansion to cool the two "stages" of the cryo-pump.

[0053] The number of revolutions per minute of the regenerator has a direct impact on the amount of cooling power or watts that the cooler can maintain at a set temperature.

[0054] Regeneration is described as the pump undergoing a set routine to heat up, purge, and evacuate the pump so that it can be cooled to operating temperature, and regeneration completes when it signals to the customer that it is ready for use.

[0055] The test routine will be run after regeneration, and whenever a service engineer accesses the cryogenic pump module and commands the test routine. Performance capabilities will be compared to previous tests to predict the performance of the cryogenic pump / system with the assistance of the service engineer.

[0056] Performance, reliability, and safety are critical to pump users, so the ability to predict unexpected events is of paramount importance.

[0057] The health check routine is designed to examine how the pump's performance changes over time and help maintenance engineers identify potential degradation in that performance.

[0058] This allows service engineers to visit customers to diagnose potential system problems and mitigate them. This may involve maintaining the system or removing / repairing the pump / compressor or accessory before interrupting the customer's process, thus reducing system tool downtime.

[0059] Data collected during test routines is stored in a data storage device associated with the pump and can be retrieved by a maintenance engineer or sent to a remote server that analyzes the data in response to signals received from other remote servers requesting the data. This data can be analyzed to determine current performance and how pump performance changes over time.

[0060] Figure 1 A cryogenic pump 5 according to an embodiment is shown. The cryogenic pump 5 is cooled by a refrigeration unit 16, which is controlled by a control and diagnostic circuit 14. The refrigeration unit 16 includes a finger-shaped cryotherm (cold finger) extending into the cryogenic pump container, and includes a first stage for cooling the inner surface of the container and a front array (not shown) arranged across the inlet 7, and a second stage for cooling the cryogenic plate 10 to a temperature colder than the first stage temperature. The cryotherm includes a variable-speed motor 17 for driving a refrigerant, in this case, helium surrounding the refrigeration system.

[0061] Heaters 18a and 18b are present, which are associated with the first and second stage coolers, respectively, and these heaters can be used to provide heat during the regeneration and testing of the cryogenic pump.

[0062] The cryogenic pump 5 is used to evacuate the vacuum chamber to a high vacuum. This vacuum chamber can be used, for example, in semiconductor processing, such as chip manufacturing. The cryogenic pump is a trapping pump, in which gas molecules entering the cryogenic pump are trapped by condensation or adsorption onto the cooled surfaces of the cryogenic pump. This means that the cryogenic pump will need to be regenerated periodically to remove the trapped condensate.

[0063] Control circuit 14 controls the operation of the cryogenic pump and controls the regeneration cycle during the regeneration of the cryogenic pump. During the regeneration cycle, the cryogenic pump is typically isolated from the vacuum chamber by a gate valve, and heaters 18a and 18b are used to increase the temperature of the cryogenic pump while purge gas is introduced to remove any evaporated molecules. This regeneration is performed periodically when the condensate in the pump rises above a value at which the pump ceases to operate effectively.

[0064] In addition to controlling the regeneration cycle, the control and diagnostic circuitry 14 can be configured to execute a test routine after the regeneration cycle is complete, when the condition of the cryogenic pump is known. This test routine is used to determine the pump's health or performance and allows monitoring of pump performance degradation, predicting pump failure before it occurs. Unexpected pump failure can be very costly, especially when the pump is used in chip manufacturing, and therefore, predicting failure in advance and allowing for pump replacement before failure has many advantages.

[0065] A test routine is used to determine the current cooling capacity of the cryogenic pump 5 when the motor in the refrigeration unit 16 operates at a constant speed. The motor within the refrigeration unit 16 delivers refrigerant (in this case, helium) around the refrigeration system and is typically a variable-speed motor, allowing for variations in pump capacity and cooling power. During the test routine, the pump speed is set to a predetermined value, and temperature sensors 12a and 12b are used to determine the temperatures of the first and second stage coolers and transmit the signals to circuit 14. Circuit 14 controls heaters 18a and 18b associated with the first and second stage coolers, maintaining the temperatures of the first and second stage coolers at certain predetermined values. These values ​​can be selected as the normal operating temperature of the cryogenic pump. The amount of power required by the heaters to maintain this temperature is an indication of the cooling power of the cryogenic pump 5 and can be stored in data memory 13. A maintenance engineer can then access this data memory and determine the current performance, any changes in performance, and the rate of change of the cryogenic pump's performance over time.

[0066] In some embodiments, an input / output port 19 is also provided, which can be used to output the current performance of the cryogenic pump to the operator. This can be output as an indicator accessible to the pump operator. The indicator can be a numerical value indicating the pump's current performance, which may be related to a percentage of optimal performance, or it can simply be a color indicating whether the performance is currently good or not so good. In some cases, it may include an instruction to contact a service engineer. In other cases, the data can be output via a transmitter to a configured remote server. This can occur in response to receiving a request for data from the remote server. The remote server can be a server configured to analyze data received from multiple pumps and monitor the performance of the multiple pumps and any changes in performance based on that data.

[0067] In some embodiments, input / output port 19 can also be used to receive values ​​input by a service engineer, indicating the motor speed and / or first and second stage temperatures to be used in the test routine. This allows these values ​​to be updated as needed. In this respect, different temperatures and / or motor speeds may be more suitable for pump testing depending on the pump's operating conditions.

[0068] Figure 2 A flowchart illustrating the steps in a method for monitoring the performance or health of a pump according to an embodiment is shown. Initially, in step D5, it is determined whether the regeneration cycle has been completed.

[0069] When it is determined that the process has been completed, the test routine is started in step S10. In this regard, in some embodiments, instead of performing S10 after each regeneration cycle, the test routine may be started only after a certain number of regeneration cycles have been completed. In this case, there may be intermediate steps to determine whether the counter has counted to that specific number, and the counter is incremented after each regeneration cycle has been completed.

[0070] Once the test routine has been started, in step S20, the motor speed is set to a predetermined value and the cryogenic pump begins cooling. In step S30, the temperatures of the first and second stages are set to predetermined values. The predetermined temperature and speed of the motor can be setpoints in the control / diagnostic circuit, and / or they can be values ​​that can be updated in response to input from a service engineer. In step S40, the heater is controlled to maintain the temperatures of the first and second stage coolers at the desired predetermined temperatures. The power consumed by the heater to maintain said temperature is an indication of the current performance of the cryogenic pump, and therefore, in step S50, the power applied to and consumed by the heater is determined, and this value is stored in step S60 as an indication of the pump's performance. This value can be stored along with an indication of the regeneration cycle, after which a test routine from which this value is derived is executed.

[0071] In S70, the current power can be compared with a previous value to determine the change and / or rate of change in pump performance. This, along with the actually determined power value, can be used to determine the current pump performance. In some embodiments, an indicator of the current performance may be output in step S80. The pump regeneration cycle and test are now complete, and normal operation resumes. The diagnostic circuit then continues in step D15 to determine when the next regeneration cycle begins, and when the next regeneration cycle has begun, it waits until the cycle has been completed before it can restart the test routine in S10.

[0072] Although illustrative embodiments of the invention have been disclosed in detail herein with reference to the accompanying drawings, it should be understood that the invention is not limited to the precise embodiments, and that various changes and modifications can be made therein by those skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

[0073] Figure Labels

[0074] 5. Cryogenic pump

[0075] 7 entrances

[0076] 10 cryoplate

[0077] Temperature sensors 12a and 12b

[0078] 13 Data Storage

[0079] 14 Control and Diagnostic Circuits

[0080] 16 Refrigeration Units

[0081] 17. Variable speed motor

[0082] 18a, 18b heaters

[0083] 19 Input / Output Ports

Claims

1. A method for monitoring the performance of a cryogenic pump, the method comprising: After the regeneration cycle is completed, the cryogenic pump is controlled to execute a predetermined test routine in order to test the performance of the cryogenic pump under predetermined conditions. The cryogenic pump is monitored during the predetermined test routine to collect data indicative of the performance of the cryogenic pump; The data collected during monitoring that indicates the performance is stored. The steps of controlling the cryogenic pump to execute a predetermined test routine include: The variable speed motor is controlled to operate at a predetermined motor speed, and the variable speed motor controls the refrigerant flow through the refrigeration system of the cryogenic pump; A first predetermined temperature is set for the first stage of the cooler, and a second predetermined temperature is set for the second stage of the cooler; and Control the heaters associated with the first and second stages of the refrigerator to maintain the first predetermined temperature and the second predetermined temperature; and The step of determining the performance of the cryogenic pump includes: determining the power applied to the heater to maintain the first predetermined temperature and the second predetermined temperature.

2. The method of claim 1, wherein the method controls the cryogenic pump to periodically execute the predetermined test routine after at least a subset of the regeneration cycle.

3. The method according to claim 1 or 2, comprising: Another step in determining the performance of the cryogenic pump based on the collected data.

4. The method of claim 3, wherein the further step of determining the performance of the cryogenic pump comprises: The data obtained from the current test routine will be compared with the data obtained from the previous test routine.

5. The method according to claim 1 or 2, wherein the method comprises: Another step is to output data indicating the performance of the cryogenic pump.

6. The method of claim 5, wherein the further step of outputting the data comprises: Receive a request for the data, and output the data in response to the request.

7. The method according to claim 1 or 2, wherein the predetermined test routine comprises: Determine the cooling level provided by the cryogenic pump at the predetermined motor speed.

8. A computer program comprising computer-readable instructions, which, when executed by a processor, control the processor to perform the steps of the method according to any one of claims 1-7.

9. A control and diagnostic circuit for a cryogenic pump, comprising a control circuit and a diagnostic circuit; The control circuit is configured to determine when a regeneration cycle has been completed, and after the completion of the regeneration cycle, to control the cryogenic pump to execute a predetermined test routine for testing the performance of the cryogenic pump under predetermined conditions; and The diagnostic circuit is configured as follows: The performance of the cryogenic pump is monitored during the predetermined test routine; and Store data obtained from the monitoring that indicates the performance. in, The control circuit is configured to control the cryogenic pump to perform the predetermined test routine by: The variable speed motor is controlled to operate at a predetermined motor speed, and the variable speed motor controls the refrigerant flow through the refrigeration system of the cryogenic pump; A first predetermined temperature is set for the first stage of the refrigerator, and a second predetermined temperature is set for the second stage of the refrigerator; as well as Control the heaters associated with the first and second stages of the refrigerator to maintain the first predetermined temperature and the second predetermined temperature; and The diagnostic circuit is configured to determine the power applied to the heater to maintain the first predetermined temperature and the second predetermined temperature to determine the performance of the cryogenic pump.

10. The control and diagnostic circuit of claim 9, wherein the control circuit is configured to control the cryogenic pump to periodically execute the predetermined test routine after at least a subset of the regeneration cycle.

11. The control and diagnostic circuit according to claim 9 or 10, wherein the diagnostic circuit is configured to determine the performance of the cryogenic pump based on collected data.

12. The control and diagnostic circuit of claim 11, wherein the diagnostic circuit is configured to determine the performance of the cryogenic pump by comparing data obtained from the current test routine with data obtained from a previous test routine.

13. The control and diagnostic circuit according to claim 9 or 10, wherein the diagnostic circuit is configured to output data indicating the performance of the cryogenic pump.

14. The control and diagnostic circuit of claim 13, wherein the diagnostic circuit is configured to output the data in response to receiving a request for the data.

15. The control and diagnostic circuit according to claim 9 or 10, wherein, The predetermined test routine includes determining the cooling level provided by the cryogenic pump at the predetermined motor speed.

16. A cryogenic pump, comprising: Refrigeration unit; A variable speed motor is used to control the refrigerant flow through the cooling system of the cryogenic pump; as well as The control and diagnostic circuit according to any one of claims 9 to 15.

17. The cryogenic pump according to claim 16, The refrigeration unit comprises a two-stage refrigeration unit; and the cryogenic pump further comprises: Temperature sensors for monitoring the temperature of the first stage of the two-stage refrigerator and temperature sensors for monitoring the temperature of the second stage of the two-stage refrigerator; as well as A heater for supplying heat to the first stage of the two-stage refrigerator and a heater for supplying heat to the second stage of the two-stage refrigerator.

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