Method for calibrating a pressure determination and for pressure determination in a measuring vacuum switching tube, pressure calibration device and pressure measuring device

Abstract

The invention relates to a method for calibrating a pressure measurement, comprising the steps of: providing at least one vacuum switching tube (1); applying an electric field (23) and a magnetic field (24) to the interior (26) of the vacuum switching tube at a plurality of different pressures (p x ) of the vacuum in the interior space, such that a gas discharge is generated in the interior space, wherein a plurality of gas discharges are generated at each of the pressures, wherein the electric field in the interior space has an orientation different from the magnetic field; Determine for each of the gas discharges a delay (Δt) which is the time interval between a time zero (t0) and a generation time (t1), wherein the time zero is the first time in time at which the electric field and the magnetic field are present, wherein the gas discharge is generated at the generation time; Determine for each a distribution (fp x) the delays at each of the pressures; determining a confidence interval (C x ) the distribution at each of the pressures, with a lower limit (uG) for each x ) and an upper limit (oG x ); Determining an upper calibration function (oF) where an upper pressure of the vacuum is determined based on the upper limits from the respective delays (Δt), the majority of gas discharges for each of the pressures px.

Description

[0001] The invention relates to a method for calibrating a pressure determination, a method for determining pressure in a measuring vacuum switching tube, a pressure calibration device and a pressure measuring device.

[0002] A vacuum switching tube, such as that described in JP S54-175560 U, is designed to perform electrical switching operations under a vacuum. To interrupt an electric current, the two electrodes in the vacuum switching tube are moved from a contact state, in which the two electrodes are in contact, to a spaced-apart state, in which the two electrodes are separated. In the spaced-apart state, the vacuum electrically isolates the two electrodes from each other. To ensure the vacuum switching tube functions correctly, a low vacuum pressure is required. Conventionally, the vacuum pressure is determined using the magnetron method. In this method, electrons are accelerated in an electric field and forced by a magnetic field onto spiral paths, so that the electrons have to travel a significantly longer path to the anode.Gas molecules struck by these electrons can be ionized, allowing a gas discharge to build up in the vacuum. The current intensity of the gas discharge correlates with the vacuum pressure.

[0003] The delay times, after which the gas discharge actually ignites following the application of the electric and magnetic fields, vary considerably and can be up to 30 minutes or longer. The delay times are longer the lower the vacuum pressure. This disadvantageously results in a long measurement time for determining the vacuum pressure. Because the pressure of each vacuum switching tube is determined during its manufacture, the long measurement time also negatively extends the production time of the vacuum switching tubes.

[0004] The object of the invention is therefore to provide a method for calibrating a pressure determination, a method for determining a pressure in a measuring vacuum switching tube, a pressure calibration device and a pressure measuring device, with which a measurement time for determining a pressure in a vacuum switching tube is short.

[0005] The inventive method for calibrating a pressure determination comprises the steps of: b) providing at least one vacuum switching tube, which has a first electrode and a second electrode, which have a contact state in which the first electrode and the second electrode are in contact with each other, and a separation state in which the first electrode and the second electrode are spaced apart from each other, and a housing which defines an interior space in which the first electrode and the second electrode are arranged, and which maintains a vacuum in the interior space, so that in the separation state the first electrode and the second electrode are electrically isolated from each other by the vacuum;c) Applying an electric field and a magnetic field to the interior at a plurality of different pressures corresponding to the vacuum, such that a gas discharge is generated in the interior, wherein a plurality of gas discharges are generated at each of the pressures, and wherein the electric field has an orientation different from the magnetic field in the interior; d) Determining, for each of the gas discharges, a delay which is the time interval between a time zero and a generation time, wherein the time zero is the first time at which both the electric field and the magnetic field are applied to the interior, and the gas discharge forms at the generation time; e) Determining a distribution of the delays at each of the pressures;f) Determining a confidence interval of the distribution for each of the pressures, wherein each confidence interval has a lower bound and an upper bound; g) Determining an upper calibration function, wherein an upper pressure of the vacuum is determined from the respective delays (Δt), the majority of gas discharges for each of the pressures px, wherein the upper pressures are determined based on the upper bounds.

[0006] The invention is based on the finding that the upper calibration function obtained according to the inventive method for calibrating the pressure determination decreases monotonically with increasing delays; that is, the longer the delay, the lower the upper pressure. Therefore, the more time elapses after the application of the electric and magnetic fields without the gas discharge being generated, the lower the upper pressure. The upper pressure indicates that, with a certain probability, the vacuum pressure is at most the upper pressure. This specific probability is derived from the confidence coefficient of the confidence interval. The confidence coefficient indicates the proportion of events that lie within the confidence interval. For example, if the confidence coefficient is chosen to be 95%, then the probability that the pressure is at most the upper pressure is 97.5%.It is now conceivable to limit the measurement time for determining the pressure by defining an upper limit pressure in the upper calibration function, which is considered non-critical. After a limit delay corresponding to this upper limit pressure, the pressure measurement can be terminated, even if the gas discharge has not yet occurred. This can shorten the measurement time compared to a conventional method where the generation of the gas discharge is always awaited. Because the pressure inside the vacuum switching tube is measured during its manufacture, this can also shorten the manufacturing time of the vacuum switching tube.

[0007] One of the at least one vacuum switching tube is preferably a calibration vacuum switching tube having a through-hole via which the interior of the calibration vacuum switching tube can be pressurized from outside the calibration vacuum switching tube with a gas having different pressures, wherein the vacuum pressures of the calibration vacuum switching tube outside the calibration vacuum switching tube are determined by means of a pressure sensor. This has the advantage that the pressures can be freely selected and set.

[0008] It is preferred that a plurality of the vacuum switching tubes be provided, comprising a group of production vacuum switching tubes that do not have a through-hole via which the interior of the production vacuum switching tube can be pressurized with gas from outside the production vacuum switching tube, wherein the vacuum pressures of the production vacuum switching tubes are determined by measuring the current of the gas discharge. This advantageously allows manufacturing tolerances that occur during the production of the production vacuum switching tubes to be taken into account. It is conceivable that the current of the gas discharges generated in the calibration vacuum switching tube is measured, thus enabling a further calibration to be performed, based on which the pressure in the production vacuum switching tube can be deduced from the current of the gas discharge in the production vacuum switching tube.

[0009] It is particularly preferred that both the calibration vacuum switching tube and the production vacuum switching tubes are provided, wherein the interior of the production vacuum switching tubes is identical in construction to the interior of the calibration vacuum switching tube, except for the absence of the through-hole. This allows the upper calibration function to be determined with high accuracy. The walls that delimit the interior of the production vacuum switching tubes preferably comprise the same material or materials as the walls that delimit the interior of the calibration vacuum switching tube. This results in particularly high accuracy of the upper calibration function.

[0010] The inventive method for determining pressure in a measuring vacuum switching tube comprises the following steps: a) calibrating the pressure determination by performing steps b) to g); h) providing the measuring vacuum switching tube, which has a first electrode and a second electrode, which have a contact state in which the first electrode and the second electrode are in contact with each other, and a separation state in which the first electrode and the second electrode are separated from each other, as well as a housing that delimits an interior space in which the first electrode and the second electrode are arranged, and which maintains a vacuum in the interior space, so that in the separation state the first electrode and the second electrode are electrically isolated from each other by the vacuum;i) Applying an electric measuring field and a measuring magnetic field to the interior of the measuring vacuum switching tube such that a measuring gas discharge can be generated in the interior of the measuring vacuum switching tube; j) Determining a measurement delay, which is the time interval between a measurement time zero point and a measurement generation time, wherein the measurement time zero point is the first time in time at which both the electric measuring field and the measuring magnetic field are applied to the interior of the measuring vacuum switching tube, and wherein the measuring gas discharge is generated at the measurement generation time; k) Determining the upper pressure corresponding to the measurement delay from the upper calibration function.

[0011] It is preferred that the electric measuring field be switched off if, after a threshold period following the zero point of the measurement time, the measuring gas discharge has not yet formed. This advantageously limits the measurement duration. It is also conceivable to switch off the measuring magnetic field together with the electric measuring field.

[0012] The measuring vacuum switching tube preferably has no through-hole through which the interior of the measuring vacuum switching tube can be pressurized with gas from outside the measuring vacuum switching tube, wherein the interior of the measuring vacuum switching tube is structurally identical to the interior of the at least one vacuum switching tube, except for the optional presence of the through-hole. This allows the pressure to be determined with high accuracy. It is preferred that the walls delimiting the interior of the measuring vacuum switching tubes are made of the same material or materials as the walls delimiting the interior of the at least one vacuum switching tube. This allows the pressure to be determined with particularly high accuracy.

[0013] The pressure calibration device according to the invention is configured to carry out the method for calibrating the pressure determination. The pressure measuring device according to the invention is configured to carry out the pressure determination in the measuring vacuum switching tube.

[0014] The invention will be explained in more detail below with reference to the attached schematic drawings. These show Fig. 1 a top view of a pressure calibration device and a pressure measuring device according to the invention, Fig. 2 a section through a vacuum switching tube of the pressure calibration device, Fig. 3 an example of a current flow, Fig. 4 a plurality of exemplary distributions, Fig. 5 an exemplary upper calibration function and an exemplary lower calibration function as well as Fig. 6 a section through a calibration vacuum switching tube and a vacuum system.

[0015] How it looks Fig. 1 and Fig. As can be seen in Figure 6, a method for calibrating a pressure measurement comprises the following steps: b) Providing at least one vacuum switching tube 1 (see Figure 6) Fig. 2) comprising a first electrode 3 and a second electrode 4, which have a contact state in which the first electrode 3 and the second electrode 4 are in contact with each other, and a separation state in which the first electrode 3 and the second electrode 4 are separated from each other, and a housing 2 which delimits an interior space 26 in which the first electrode 3 and the second electrode 4 are arranged, and which maintains a vacuum in the interior space 26, such that in the separation state the first electrode 3 and the second electrode 4 are electrically isolated from each other by the vacuum; c) applying an electric field 23 and a magnetic field 24 to the interior space 26 at a plurality of different pressures p x, which has a vacuum, so that a gas discharge is generated in the interior 26, with each of the pressures p x a plurality of gas discharges are generated, wherein in the interior space 26 the electric field 23 has an orientation different from the magnetic field 24; d) Determine for each of the gas discharges a delay Δt (see Fig. 3) which is the time interval between a time zero t0 and a generation time t1, where the time zero t0 is the first time in time at which both the electric field 23 and the magnetic field 24 are applied to the interior 26, and where the gas discharge forms at the generation time t1; e) Determining a distribution fp in each case x the delays Δt at each of the pressures p x f) Determining a confidence interval C x the distribution fp x at each of the pressures p x , where each of the confidence intervals C xeach a lower limit uG x and each an upper limit oG x has; g) Determining an upper calibration function oF, wherein an upper pressure of the vacuum is determined for a plurality of delays Δt, the upper pressures being determined based on the upper limits oG x be determined.

[0016] Fig. Figure 2 shows that the vacuum switching tube 1 provided in step b) can have an axial direction 31, a radial direction 32 related to the axial direction 31, and a circumferential direction 33 related to the axial direction 31. The first electrode 3 can be fixedly arranged relative to the housing 2, and the second electrode 4 can be longitudinally displaceable in the axial direction 31 relative to the housing 2. For this purpose, the vacuum switching tube 1 can have a bearing 9 on which the second electrode 4 can slide in and against the axial direction 31. It is conceivable to displace the second electrode 4 mechanically, in particular by using a spring accumulator. Starting from the in Fig. In the contact state shown in Figure 2, the first electrode 3 and the second electrode 4 can be brought into a spaced-away state by displacing the second electrode 4 away from the first electrode 4 in the axial direction 31. The first electrode 3 can have a first contact surface 7 and the second electrode 4 can have a second contact surface 8, with the first contact surface 7 and the second contact surface 8 being arranged in the interior space 26. The first electrode 3 can have a thickening at its longitudinal end facing the second electrode 4, and the second electrode 4 can have a thickening at its longitudinal end facing the first electrode 3.The first contact surface 7 and the second contact surface 8 are in contact in the contact state, allowing a current to flow from the first electrode 3 to the second electrode 4, and are spaced apart from each other in the separation state, preventing the current from flowing from the first electrode 3 to the second electrode 4.

[0017] The first electrode 3 can have a first terminal 5 located outside the housing 2, and the second electrode 4 can have a second terminal 6 located outside the housing 2. Electrical conductors can be connected to the first terminal 5 and the second terminal 6 in an electrically conductive manner. The vacuum switching tube 1 can have a bellows 10 which is attached to the bearing 9 and to the first electrode 3, in particular to an electrode projection 25 extending radially 32 from the remaining first electrode 3, enclosing the first electrode 3 and sealing the interior 26 against a vacuum.

[0018] How it looks Fig. As can be seen in Figure 2, the housing 2 can be formed from several sub-housings. The housing 2 can, for example, have a switching chamber housing 14, which is made of or consists of a metal or alloy. The switching chamber housing 14 can completely enclose a switching chamber 13 in the circumferential direction 33, which is part of the interior 26. The first contact surface 7 and the second contact surface 8 are arranged in the switching chamber 13.

[0019] The housing 2 can, for example, comprise a first ceramic housing 17 arranged opposite the axial direction 31 of the switching chamber housing 14, and / or a second ceramic housing 18 arranged in the axial direction 31 of the switching chamber housing 14. The switching chamber housing 14 can be electrically isolated from other components of the vacuum switching tube 1 by means of the first ceramic housing 17 and / or the second ceramic housing 18. It is conceivable that the first ceramic housing 17 and / or the second ceramic housing 18 are formed in one piece or are formed from a plurality of partial ceramic housings 19 arranged side by side in the axial direction 31.

[0020] The housing 2 can, for example, comprise a first flange housing 15, which is arranged opposite the axial direction 31 to the first ceramic housing 17 and is attached to the first electrode 3, and a second flange housing 16, which is arranged in the axial direction 31 to the second ceramic housing 18 and is attached to the bearing 19. The first flange housing 15 and the first ceramic housing 17 can fully delimit a first flange chamber 11 in the circumferential direction 33, which is part of the interior 26. The second flange housing 16 and the second ceramic housing 18 can fully delimit a second flange chamber 12 in the circumferential direction 33, which is part of the interior 26. The first flange chamber 11 and the second flange chamber 12 can have a smaller cross-section than the switching chamber 13, the cross-section having a normal parallel to the axial direction 31.

[0021] The vacuum switching tube 1 can have two chamber shields 20 attached to the switching chamber housing 14 and projecting into the interior 26, one of the two chamber shields 20 electrically shielding the first flange chamber 11 from switching chamber 13 and against metal vapor, and the other chamber shield 20 electrically shielding the second flange chamber 12 from switching chamber 13 and against metal vapor. The chamber shields 20 can be electrically connected to the switching chamber housing 14. Furthermore, for electrical shielding and shielding against metal vapor, a flange shield 21 can be attached to the first flange housing 15, which projects into the interior 26, and another flange shield 21 can be attached to the second flange housing 16, which also projects into the interior 26.In the area where the partial ceramic housings 19 meet, an intermediate shield 22 can be arranged for electrical shielding and for shielding against metal vapor, with the intermediate shield 22 projecting into the interior 26.

[0022] Fig. Figure 2 shows that the electric field 23 applied in step c) can extend from the first electrode 3 and / or the second electrode 4 to the housing 2. Both polarities are conceivable, i.e., the anode can be formed by the housing 2 as well as by the first electrode 3 and / or the second electrode 4. The first electrode 3 and the second electrode 4 can be in contact or in a spaced-apart state. In particular, the electric field 23 can extend to the switching chamber housing 14. The electric field 23 and the magnetic field 24 can enclose an angle in the interior 26, which lies, for example, in the range of 70° to 90°, in particular from 80° to 90° or from 85° to 90°. The electric field 23 can, for example, enclose an angle with the radial direction 32 which lies in a range of 0° to 30°, in particular in a range of 0° to 15° or of 0° to 5°.The magnetic field 24 can, for example, enclose an angle with the axial direction 31 which lies in a range of 0° to 30°, in particular in a range of 0° to 15° or of 0° to 5°, cf. . Fig. 2.

[0023] The different pressures can, for example, range from 10 -9 mbar up to 10 -3 mbar

[0024] Alternatively to the one in Fig. In the embodiment shown in Figure 2, in which the electric field 23 extends from the first electrode 3 and / or the second electrode 4 to the housing 2, the first electrode 3 and the second electrode 4 can be in a spaced-apart state, and the electric field 23 can extend from the first electrode 3 to the second electrode 4. Both polarities are conceivable; that is, the anode can be formed by either the first electrode 3 or the second electrode 4.

[0025] It is conceivable that the magnetic field 24 is switched on first and then the electric field 23 is switched on. Alternatively, it is conceivable that the electric field 23 and the magnetic field 24 are switched on simultaneously.

[0026] It is conceivable to determine the delay Δt by measuring the current of the gas discharge. Fig. Figure 3 shows an example of a time-resolved current I that can be measured in step d). The current (in amperes) is plotted against time t. The time-resolved current I is characterized by the fact that, during the generation of the gas discharge, the current I rises steeply to a maximum and then falls more gradually. Various methods are conceivable for determining the generation time t1 in step d). For example, the generation time t1 can be determined as the time at which the current I first reaches or exceeds a threshold current, as is also done in Fig. Figure 3 is shown. In another example, the generation time t1 can be determined as the time of the maximum. In another example, the generation time t1 can be determined as the time at which the current I first reaches a certain percentage of the current I at its maximum, such as 50%.

[0027] In Fig. 4 are examples of distributions fp determined in step e). x The graph shows the number n of events versus the delay Δt, where each gas discharge represents one event. In the specific example of Fig. Four distributions fp1, fp2, fp3 and fp4 are shown, where fp x the distribution at pressure p x The following holds true: p1>p2>p3>p4. It can be seen that with decreasing pressure p, the distributions fp x Postpone to a later time.

[0028] The distributions fp xcan have any shape, such as a Gaussian distribution.

[0029] In Fig. 4 are also examples of confidence intervals C determined in step f). x shown, where fp is used for each of the distributions x each of the confidence intervals C x can be determined. The confidence intervals C x are each of the lower limits UG x and one of the upper limits OG x limited. The confidence intervals C x They can be chosen symmetrically, i.e., an equal number of the events lie below the lower bound (UG). x as above the upper limit OG x The confidence intervals C x have a confidence coefficient γ, which indicates the proportion of events that occur within the confidence interval C. xThe confidence coefficient γ can, for example, lie in a range of 50% to 99.9%, in particular from 80% to 99% or from 85% to 95%.

[0030] In Fig. Figure 5 shows an example of an upper calibration function oF determined in step g). The upper calibration function oF can be determined by calculating the value for each of the distributions fp. x the distribution fp x associated pressure p x against the delay Δt of the distribution fp x associated upper limit OG x is plotted. From the upper calibration function oF, an upper vacuum pressure can be read for various delays Δt, indicating that the pressure p is reached with a probability of 1-(1-γ) / 2. x The maximum pressure is the upper limit of the vacuum. It is conceivable that a lower calibration function uF is determined by determining fp for each of the distributions. x the distribution fp xassociated pressure p x against the delay Δt of the distribution fp x associated lower limit uG x is plotted. From the lower calibration function uF, a lower vacuum pressure can be read for various delays Δt, indicating that with a probability of 1-(1-γ) / 2 the pressure p x The minimum is the lower pressure of the vacuum. It is conceivable that the upper calibration function oF and / or the lower calibration function uF are in the form of a lookup table and / or in the form of an adjustment function.

[0031] Fig. Figure 6 shows that one of the at least one vacuum switching tube 1 can be a calibration vacuum switching tube 28, which has a through-hole 27, through which the interior 26 of the calibration vacuum switching tube 28 can be supplied from outside the calibration vacuum switching tube 28 with a gas that corresponds to the different pressures p x has, can be actuated. The pressures p xThe vacuum pressure of the calibration vacuum switching tube 28 can be determined outside the calibration vacuum switching tube 28 using a pressure sensor 42. The pressure sensor 42 can employ a different measuring principle than the magnetron method for determining the pressure p. x use.

[0032] How it looks Fig. As can be seen in Figure 6, a vacuum system 40 can be provided together with the calibration vacuum switching tube 28, by means of which the interior 26 of the calibration vacuum switching tube 28 can be pressurized with gas from outside the calibration vacuum switching tube 28 and which includes the pressure sensor 42. The vacuum system 40 can have a tube 41, wherein the through-hole 27 connects the interior 26 to the tube 41 in a fluid-conducting manner. In particular, the interior 26 is connected to the tube 41 in a fluid-conducting manner by means of a flange connection. For example, the tube 41 can have a first flange 49 and the calibration vacuum switching tube 28 can have a second flange 50 that completely delimits the through-hole 27. The first flange 49 and the second flange 50 can form the flange connection.

[0033] The vacuum system 40 may include a pump configured to evacuate the interior 26 via the pipe 41. The pump may be a turbomolecular pump 47. The vacuum system 40 may also include a diaphragm pump 48. The pressure sensor 42 may be configured to determine the pressure in the pipe 41. The vacuum system 40 may include a shut-off device 44 located in a flow path extending from the pressure sensor 42 to the pump, configured to open and close the flow path. The vacuum system 40 may include a further pressure sensor 43 configured to determine the pressure in a flow path extending from the shut-off device 44 to the pump. The further pressure sensor 43 may be based on a different measuring principle than the magnetron method. The vacuum system 40 can have a gas reservoir 46 in which a gas is arranged that can flow into the interior 26 via the tube 41.The vacuum system 40 can have a further shut-off device 45, via which the gas reservoir 46 can be opened and closed.

[0034] It is conceivable that a majority of the vacuum switching tubes 1 are provided, which have a group of manufacturing vacuum switching tubes 29 (see Fig. 2), which do not have a through-hole via which the interior 26 of the manufacturing vacuum switching tube 29 can be pressurized with a gas from outside the manufacturing vacuum switching tube 29, wherein the pressures p xThe vacuum of the production vacuum switching tubes 29 can be determined by measuring the current I of the gas discharge. The production vacuum switching tubes 29 can, for example, originate from a conventional manufacturing process and be intended for delivery to a customer. The interior 26 of the production vacuum switching tubes 29 can be identical in construction to the interior 26 of the calibration vacuum switching tube 28, except for the absence of the through-hole 27. The walls that delimit the interior 26 of the production vacuum switching tubes 29 can be made of the same material or materials as the walls that delimit the interior 26 of the calibration vacuum switching tube 29. To determine the pressure p from the current I xTo conclude, it is conceivable to carry out a further calibration in which the current of the gas discharge in the calibration vacuum switching tube 28 is measured and thus a calibration curve is recorded, in which, for example, the current I is compared to the pressure p x The current is plotted. It is conceivable to determine the current intensity at the maximum to evaluate the current. It is conceivable to filter the time-resolved current beforehand, for example using a low-pass filter. It is also conceivable to fit the time-resolved current I with one or more functions and to use one or more fitting parameters for the current intensity.

[0035] A method for determining the pressure in a measuring vacuum switching tube 30 may comprise the steps: a) calibrating the pressure determination by performing steps b) to g); h) providing the measuring vacuum switching tube 30, which has a first electrode 3 and a second electrode 4, which have a contact state in which the first electrode 3 and the second electrode 4 are in contact with each other, and a spaced-out state in which the first electrode 3 and the second electrode 4 are spaced apart from each other, and a housing 2 which delimits an interior space 26 in which the first electrode 3 and the second electrode 4 are arranged, and which maintains a vacuum in the interior space 26, such that in the spaced-out state the first electrode 3 and the second electrode 4 are electrically isolated from each other by the vacuum;i) Applying an electric measuring field and a measuring magnetic field to the interior 26 of the measuring vacuum switching tube 30, such that a measuring gas discharge can be generated in the interior 26 of the measuring vacuum switching tube 30; j) Determining a measurement delay, which is the time interval between a measurement zero point and a measurement generation time, wherein the measurement zero point is the first time in time at which both the electric measuring field and the measuring magnetic field are applied to the interior 26 of the measuring vacuum switching tube 30, and wherein the measuring gas discharge is generated at the measurement generation time; k) Determining the upper pressure corresponding to the measurement delay from the upper calibration function oF. It is also conceivable to determine, in addition to the upper pressure, the lower pressure corresponding to the measurement delay from the lower calibration function uF.

[0036] The measurement delay can be determined identically to the delay Δt. The electric measurement field can have the same orientation and strength relative to the measuring vacuum switching tube 30 as the electric field 23 relative to the at least one vacuum switching tube 1. The measuring magnetic field can have the same orientation and strength relative to the measuring vacuum switching tube 30 as the magnetic field 24 relative to the at least one vacuum switching tube 1.

[0037] It is conceivable that the electric measuring field is switched off if the measuring gas discharge has still formed after a threshold period following the zero point of measurement. The measuring magnetic field can also be switched off along with the electric measuring field.

[0038] The measuring vacuum switching tube 30 can be a component different from the at least one vacuum switching tube 1. It is conceivable that the measuring vacuum switching tube 30 does not have a through-hole through which the interior 26 of the measuring vacuum switching tube 30 can be pressurized with a gas from outside the measuring vacuum switching tube 30, wherein the interior 26 of the measuring vacuum switching tube 30 is identical in construction to the interior 26 of the at least one vacuum switching tube 1, except for the optional presence of the through-hole. The walls that delimit the interior 26 of the measuring vacuum switching tube 30 can be made of the same material or materials as the walls that delimit the interior 26 of the at least one vacuum switching tube 1.

[0039] Fig.Figure 1 shows a pressure calibration device 60 configured to perform the pressure calibration procedure. The pressure calibration device 60 is also suitable as a pressure measuring device 61 configured to perform the pressure determination procedure. The pressure calibration device 60 and / or the pressure measuring device 61 may include a voltage source 62 configured to generate the electric field 23. The pressure calibration device 60 and / or the pressure measuring device 61 may include a magnet 63 configured to generate the magnetic field 24. The magnet 63 may, for example, be a permanent magnet and / or a coil. Reference symbol list 1 vacuum switching tube 2 cases 3 first electrode 4 second electrode 5 first connection 6 second connection 7 first contact surface 8 second contact surface 9 warehouses 10 bellows 11 first flange chamber 12 second flange chamber 13 Switching chamber 14 Switch chamber housings 15 first flange housing 16 second flange housing 17 first ceramic housing 18 second ceramic housing 19 partial ceramic housings 20-chamber screen 21 Flange screen 22 Intermediate screen 23 electric field 24 Magnetic field 25 electrode protrusion 26 Interior 27 Through hole 28 Calibration vacuum switching tube 29 Manufacturing vacuum switching tube 30 measuring vacuum switching tubes 31 Axial direction 32 Radial direction 33 Circumferential direction 40 vacuum system 41 pipe 42 Pressure sensor 43 additional pressure sensors 44 Shut-off device 45 additional shut-off device 46 Gas reservoir 47 Turbomolecular pump 48 Diaphragm pump 49 first flange 50 second flange 60 Pressure calibration device 61 Pressure measuring device 62 Voltage source 63 Magnet I electric current t time t0 Time zero t1 Production time Δt delay n number of events p x xth print fp x Distribution at an xth printing p print C x xth confidence interval uF lower calibration function oF upper calibration function uG x Lower limit of the xth confidence interval oG x Upper limit of the xth confidence interval

Claims

[1] Method for calibrating a pressure measurement, comprising the steps: b) Providing at least one vacuum switching tube (1) comprising a first electrode (3) and a second electrode (4) having a contact state in which the first electrode (3) and the second electrode (4) are in contact with each other and a separation state in which the first electrode (3) and the second electrode (4) are separated from each other, and a housing (2) comprising an interior space (26) in which the first electrode (3) and the second electrode (4) are arranged and which maintains a vacuum in the interior space (26) such that in the separation state the first electrode (3) and the second electrode (4) are electrically isolated from each other by the vacuum; c) Applying an electric field (23) and a magnetic field (24) to the interior (26) at a plurality of different pressures (p x), which has the vacuum, so that a gas discharge is generated in the interior (26), with each of the pressures (p x ) a plurality of gas discharges are generated in each case, whereby in the interior space (26) the electric field (23) has an orientation different from the magnetic field (24); d) Determine for each of the gas discharges a delay (Δt) which is the time interval between a time zero point (t0) and a generation time (t1), where the time zero point (t0) is the first time in time at which both the electric field (23) and the magnetic field (24) are applied to the interior (26), and where the gas discharge forms at the generation time (t1); e) Determine one distribution in each case (fp x )) the delays (Δt) at each of the pressures (p x ); f) Determining a confidence interval (C x ) of the distribution (fp x ) at each of the pressures (p x), where each of the confidence intervals (C x ) each a lower limit (uG x ) and each an upper limit (oG x ) has; g) Determining an upper calibration function (oF) wherein an upper pressure of the vacuum is determined from the respective delays (Δt), the plurality of gas discharges for each of the pressures px, the upper pressures being determined based on the upper limits (oG) x ) are determined. [2] Method according to claim 1, wherein one of the at least one vacuum switching tube (1) is a calibration vacuum switching tube (28) having a through-hole (27) through which the interior (26) of the calibration vacuum switching tube (28) can be supplied from outside the calibration vacuum switching tube (28) with a gas which corresponds to the different pressures (p x ) has, is subject to pressure, whereby the pressures (p x ) of the vacuum of the calibration vacuum switching tube (28) outside the calibration vacuum switching tube (28) by means of a pressure sensor (42). [3] Method according to claim 1 or 2, wherein a plurality of vacuum switching tubes (1) is provided, comprising a group of manufacturing vacuum switching tubes (29) which do not have a through-hole via which the interior (26) of the manufacturing vacuum switching tube (29) can be supplied with a gas from outside the manufacturing vacuum switching tube (29), wherein the pressures (p x ) of the vacuum of the manufacturing vacuum switching tubes (29) can be determined by measuring the current (I) of the gas discharge. [4] Method according to claim 1, wherein one of the at least one vacuum switching tube (1) is a calibration vacuum switching tube (28) having a through-hole (27) through which the interior (26) of the calibration vacuum switching tube (28) can be supplied from outside the calibration vacuum switching tube (28) with a gas which corresponds to the different pressures (p x ) has, is subject to pressure, whereby the pressures (p x) of the vacuum of the calibration vacuum switching tube (28) outside the calibration vacuum switching tube (28) are determined by means of a pressure sensor (42), wherein a plurality of the vacuum switching tubes (1) is provided, which has a group of production vacuum switching tubes (29) which do not have a through-hole via which the interior (26) of the production vacuum switching tube (29) can be supplied with a gas from outside the production vacuum switching tube (29), wherein the pressures (p x ) of the vacuum of the production vacuum switching tube (29) are determined by measuring the current (I) of the gas discharge, wherein the interior (26) of the production vacuum switching tubes (29) is identical in construction to the interior (26) of the calibration vacuum switching tube (28) except for the absence of the through-hole (27). [5] Method according to claim 4, wherein walls that define the interior (26) of the manufacturing vacuum switching tubes (29) have the same material or materials as walls that define the interior (26) of the calibration vacuum switching tube (29). [6] Method for determining the pressure in a measuring vacuum switching tube (30), comprising the steps: a) Calibrating the pressure determination according to any one of claims 1 to 5; h) Providing the measuring vacuum switching tube (30) which has a first electrode (3) and a second electrode (4) which has a contact state in which the first electrode (3) and the second electrode (4) are in contact with each other and a separation state in which the first electrode (3) and the second electrode (4) are separated from each other, and a housing (2) which defines an interior space (26) in which the first electrode (3) and the second electrode (4) are arranged and which maintains a vacuum in the interior space (26) so that in the separation state the first electrode (3) and the second electrode (4) are electrically isolated from each other by the vacuum; i) Applying an electric measuring field and a measuring magnetic field to the interior (26) of the measuring vacuum switching tube (30) so that a measuring gas discharge can be generated in the interior (26) of the measuring vacuum switching tube (30); j) Determining a measurement delay which is the time interval between a measurement time zero point and a measurement generation time, wherein the measurement time zero point is the first time in time at which both the electric measuring field and the measuring magnetic field are applied to the interior (26) of the measuring vacuum switching tube (30), wherein the measuring gas discharge is generated at the measurement generation time; k) Determining the upper pressure corresponding to the measurement delay from the upper calibration function (oF). [7] Method according to claim 6, wherein the electric measuring field is switched off if, after a threshold period after the zero point of measurement, the measuring gas discharge has not yet formed. [8] Method according to claim 6 or 7, wherein the measuring vacuum switching tube (30) does not have a through-hole via which the interior (26) of the measuring vacuum switching tube can be supplied with a gas from outside the measuring vacuum switching tube (30), wherein the interior (26) of the measuring vacuum switching tube (30) is identical in construction to the interior (26) of the at least one vacuum switching tube (1), except for the optional presence of the through-hole. [9] Method according to claim 8, wherein the walls that define the interior (26) of the measuring vacuum switching tubes (30) are made of the same material or materials as the walls that define the interior (26) of the at least one vacuum switching tube (1). [10] Pressure calibration device configured to perform a method according to any one of claims 1 to 5. [11] Pressure measuring device configured to perform a method according to any one of claims 6 to 9.

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