Rare gas recovery system and rare gas recovery method

Abstract

To provide a rare gas recovery system capable of easily recovering a rare gas at a low cost.SOLUTION: A rare gas recovery system comprises: a turbo molecular pump 100 alternately laminating a rotary blade 102 and a fixed blade 123; a first vacuum chamber 11 disposed at the upstream side of the turbo molecular pump 100; a second vacuum chamber 12 disposed at the downstream side of the turbo molecular pump 100; a first gas discharge port 134 disposed at the first vacuum chamber 11; a second gas discharge port 136 disposed at the second vacuum chamber 12; and a gas introduction port 131 disposed at one of the first vacuum chamber 11 and the second vacuum chamber 12.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rare gas recovery system equipped with a turbomolecular pump and a rare gas recovery method. [Background technology]

[0002] For example, vacuum processing apparatuses are used in the manufacturing process of semiconductor devices. In this type of vacuum processing apparatus, a processing object is placed in a vacuum chamber, and various processes, such as film formation, heat treatment, or etching, are performed on the processing object. In these various processes, a rare gas may be used, for example, to form plasma or dilute the process gas. Examples of rare gases include xenon (Xe) gas and krypton (Kr) gas.

[0003] The rare gas introduced into the vacuum chamber is evacuated from the vacuum chamber by a vacuum pump. For example, certain rare gases such as Xe gas and Kr gas are more expensive than argon (Ar) gas and helium (He) gas. From the viewpoint of economy, it is desirable to recover and reuse expensive rare gases.

[0004] Patent Document 1, listed below, discloses a vacuum treatment device and a rare gas recovery device that recover specific rare gases contained in exhaust gas. In the vacuum treatment device and the rare gas recovery device disclosed in Patent Document 1, a first trapping body (61) and a second trapping body (62) having different set temperatures are arranged in series, and these first trapping body (61) and second trapping body (62) function as cooling traps.

[0005] The set temperature of the second capture body (62) arranged upstream is set higher than the condensation temperature of the gas to be collected (gas to be collected), and the set temperature of the first capture body (61) arranged downstream is set lower than the condensation temperature of the gas to be collected. Then, impurities having a lower vapor pressure than the gas to be collected are condensed in the second capture body (62), and the gas to be collected is condensed in the first capture body (61), thereby selectively collecting the gas to be collected. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-76194 Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional rare gas recovery device disclosed in Patent Document 1, the rare gas is recovered by cooling it to below its condensation temperature. For example, to recover Kr, it is necessary to cool the cold trap (the first trapping body (61) and the second trapping body (62)) to below 40 K (-233°C), which requires a high-performance refrigerator. This makes the equipment configuration for recovering the rare gas complicated and increases costs. In addition, the temperature of the cold trap rises due to the heat of condensation of the gas, making it difficult to continuously condense a large amount of gas. Another issue is that it takes a long time to raise and lower the temperature of the cold trap when recovering the rare gas.

[0008] An object of the present invention is to provide a rare gas recovery system and a rare gas recovery method that can recover rare gases easily and at low cost. [Means for solving the problem]

[0009] (1) In order to achieve the above object, the present invention provides: A turbomolecular pump in which rotors and fixed blades are stacked alternately; a first vacuum chamber disposed upstream of the turbomolecular pump; a second vacuum chamber disposed downstream of the turbomolecular pump; a first gas exhaust port disposed in the first vacuum chamber; a second gas exhaust port disposed in the second vacuum chamber; a gas inlet disposed in one of the first vacuum chamber or the second vacuum chamber; a first valve disposed in the first gas exhaust port and capable of exhausting gas from within the first vacuum chamber; a second valve disposed in the second gas exhaust port and capable of exhausting gas from within the second vacuum chamber; a third valve disposed at the gas inlet and capable of introducing a mixed gas containing a plurality of types of rare gases as gas components into one of the first vacuum chamber or the second vacuum chamber; a rare gas recovery system that operates the turbomolecular pump and changes a combination of opening and closing of the first valve, the second valve, and the third valve in a time series to separate and recover the gas components of the mixed gas, closing the first valve and the second valve and opening the third valve to introduce the mixed gas into the first vacuum chamber or the second vacuum chamber; Next, the third valve is closed, Next, the first valve is opened to exhaust the gas components in the first vacuum chamber from the first vacuum chamber; Subsequently, the rare gas recovery system opens the second valve to discharge the gas components in the second vacuum chamber from the second vacuum chamber. (2) In order to achieve the above object, another aspect of the present invention is to With respect to an average incidence angle calculated from an average molecular velocity of a gas component with a large molecular weight among the mixed gas introduced from the gas inlet and a circumferential velocity of the rotor blade, 2. The rare gas recovery system according to claim 1, wherein the elevation angles of at least one of the rotary blades and the fixed blades of the turbomolecular pump are matched within ±10 degrees. (3) In order to achieve the above object, another aspect of the present invention is to 3. The rare gas recovery system according to claim 1, wherein the first vacuum chamber and the second vacuum chamber are configured inside a casing of the turbomolecular pump. (4) In order to achieve the above object, another aspect of the present invention is to The turbomolecular pump is configured to be able to set at least two different rotation speeds, 4. The rare gas recovery system according to claim 1, wherein the system is configured so that several types of gases can be separated by decreasing the rotation speed from a relatively high rotation speed. (5) In order to achieve the above object, another aspect of the present invention is to A turbomolecular pump in which rotors and fixed blades are stacked alternately; a first vacuum chamber disposed upstream of the turbomolecular pump; a second vacuum chamber disposed downstream of the turbomolecular pump; a first gas exhaust port disposed in the first vacuum chamber; a second gas exhaust port disposed in the second vacuum chamber; a gas inlet disposed in one of the first vacuum chamber or the second vacuum chamber; a first valve disposed in the first gas exhaust port and capable of exhausting gas from within the first vacuum chamber; a second valve disposed in the second gas exhaust port and capable of exhausting gas from within the second vacuum chamber; a third valve disposed at the gas inlet and capable of introducing a mixed gas containing a plurality of types of rare gases as gas components into one of the first vacuum chamber or the second vacuum chamber, a rare gas recovery method for separating and recovering the gas components of the mixed gas by operating the turbomolecular pump and changing a combination of opening and closing of the first valve, the second valve, and the third valve in a time series, closing the first valve and the second valve and opening the third valve to introduce the mixed gas into the first vacuum chamber or the second vacuum chamber; Next, the third valve is closed, Next, the first valve is opened to exhaust the gas components in the first vacuum chamber from the first vacuum chamber; Subsequently, the second valve is opened to discharge the gas component in the second vacuum chamber from the second vacuum chamber. [Effects of the Invention]

[0010] According to the above invention, it is possible to provide a rare gas recovery system and a rare gas recovery method that can recover rare gases easily and at low cost. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram schematically illustrating a rare gas recovery system according to an embodiment of the present invention. [Figure 2] 1 is an explanatory diagram showing a longitudinal section of a turbomolecular pump and its surroundings in a rare gas recovery system according to an embodiment of the present invention; [Figure 3] FIG. 2 is a circuit diagram of an amplifier circuit. [Figure 4] 10 is a time chart showing control when a current command value is larger than a detection value. [Figure 5] 10 is a time chart showing control when a current command value is smaller than a detection value. [Figure 6] 1 is a diagram showing the operations relating to each step of a rare gas recovery method according to one embodiment of the present invention in order. [Figure 7] 10 is a table showing simulation results relating to the partial pressure in the first vacuum vessel and the partial pressure in the second vacuum vessel at the start of the fifth operation and at the start of the sixth operation. [Figure 8] 10(a) is a graph showing the relationship between the elapsed time and the partial pressure of each gas during the fifth operation, and FIG. 10(b) is a graph showing the relationship between the elapsed time and the content of each gas during the fifth operation. [Figure 9] FIG. 1(a) is an explanatory diagram showing the relationship between He and the rotary blades, and FIG. 1(b) is an explanatory diagram showing the relationship between Kr and the rotary blades. [Figure 10] 1 is a diagram showing the relationship between the number of blade stages and the compression ratio of each gas. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a rare gas recovery system and a rare gas recovery method according to one embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a schematic configuration of a rare gas recovery system 10 according to one embodiment of the present invention. Fig. 2 shows a specific configuration of a main part of the rare gas recovery system 10.

[0013] First, the schematic configuration will be explained using Figure 1. This rare gas recovery system 10 includes a turbomolecular pump 100, and recovers a rare gas using this turbomolecular pump 100. Furthermore, the rare gas recovery system 10 includes a first vacuum vessel (first vacuum chamber) 11 and a second vacuum vessel (second vacuum chamber) 12. The first vacuum vessel 11 is disposed upstream of the turbomolecular pump 100 (upper side of Figure 1), and the second vacuum vessel 12 is disposed downstream of the turbomolecular pump 100 (lower side of Figure 1).

[0014] A first valve 14 is connected to the first vacuum vessel 11 via a first piping section 13, and a second valve 16 is connected to the second vacuum vessel 12 via a second piping section 15. The connection between the first vacuum vessel 11 and the first valve 14 and the connection between the second vacuum vessel 12 and the second valve 16 may be made by directly joining flanges together, or may be made via an intervening piping component.

[0015] A third valve 18 is connected to the first vacuum vessel 11 via a third piping section 17. The third valve 18 is located between the first vacuum vessel 11 and a vacuum chamber of a vacuum processing device (such as a semiconductor manufacturing device, not shown). The first vacuum vessel 11 and the third valve 18 may be connected by directly joining flanges together, or may be connected via a piping component.

[0016] The first valve 14, the second valve 16, and the third valve 18 may all be of a type that is manually opened and closed, or may be of a type that is automatically opened and closed using a control device (controller).Furthermore, there may be a mixture of manually opened and closed valves and automatically opened and closed valves.

[0017] Fig. 2 shows a more specific configuration of the turbomolecular pump 100, the first vacuum vessel 11, and the second vacuum vessel 12 described above. In Fig. 2, the turbomolecular pump 100 is disposed inside a cylindrical vessel-shaped case (casing) 130. The case 130 is configured by coaxially combining an outer cylinder 127 and a base portion 129. An open end portion (reference number omitted) of the base portion 129 is inserted into an open end portion (reference number omitted) of the outer cylinder 127 facing the base portion 129, and the outer cylinder 127 and the base portion 129 are airtightly joined via bolts (reference numbers omitted) or the like.

[0018] The above-mentioned first vacuum vessel 11 and second vacuum vessel 12 are formed inside the case 130. The first vacuum vessel 11 is formed inside the outer cylinder 127, and the second vacuum vessel 12 is formed inside the base portion 129. Furthermore, a gas inlet 131, a first gas outlet 134, and a second gas outlet 136 are opened in the case 130.

[0019] 1 is connected to the first gas outlet 134, and a piping part 15a that constitutes the second piping part 15 is connected to the second gas outlet 136. In addition, a piping part 17a that constitutes the third piping part 17 is connected to the gas inlet 131. A general vacuum piping joint can be applied to either piping part.

[0020] As described above, within the case 130, the first vacuum vessel 11 is formed on the upstream side of the turbomolecular pump 100, and the second vacuum vessel 12 is formed on the downstream side. The case 130 of the turbomolecular pump 100 is used in common to form the first vacuum vessel 11 and the second vacuum vessel 12. The case 130 extends to the upstream side of the turbomolecular pump 100 (upper side in FIG. 2) to form the first vacuum vessel 11, and extends to the downstream side of the turbomolecular pump 100 (lower side in FIG. 2) to form the second vacuum vessel 12.

[0021] The turbomolecular pump 100 includes a rotor 103 having a plurality of rotor blades 102 (102a, 102b, 102c). Each rotor blade 102 is formed radially on the periphery of the rotor 103. Each rotor blade 102 has a number of turbine blades (rotary blades 132 shown schematically in FIGS. 9(a) and 9(b)) formed along the circumferential direction for sucking in and exhausting gas. In this embodiment, the number of stages (number of stacked stages) of the rotor blades 102 (102a, 102b, 102c) is three.

[0022] A rotor shaft 113 is attached to the center of the rotor 103, and this rotor shaft 113 is supported in the air and its position is controlled by, for example, a five-axis controlled magnetic bearing. The rotor 103 is generally made of a metal such as aluminum or an aluminum alloy.

[0023] The upper radial electromagnets 104 are arranged in pairs on the X-axis and the Y-axis. Four upper radial sensors 107 are provided adjacent to the upper radial electromagnets 104 and corresponding to each upper radial electromagnet 104. The upper radial sensors 107 are, for example, inductance sensors or eddy current sensors having conductive windings, and detect the position of the rotor shaft 113 based on changes in the inductance of the conductive windings, which change according to the position of the rotor shaft 113. The upper radial sensors 107 are configured to detect the radial displacement of the rotor shaft 113, i.e., the rotating body 103 fixed thereto, and send the detected displacement to the control device 200.

[0024] In this control device 200, for example, a compensation circuit having a PID adjustment function generates an excitation control command signal for the upper radial electromagnet 104 based on a position signal detected by the upper radial sensor 107, and an amplifier circuit 150 (described later) shown in Figure 3 controls the excitation of the upper radial electromagnet 104 based on this excitation control command signal, thereby adjusting the upper radial position of the rotor shaft 113.

[0025] The rotor shaft 113 is made of a high magnetic permeability material (iron, stainless steel, etc.) and is attracted by the magnetic force of the upper radial electromagnets 104. Such adjustment is performed independently in the X-axis direction and the Y-axis direction. The lower radial electromagnets 105 and the lower radial sensors 108 are arranged in the same manner as the upper radial electromagnets 104 and the upper radial sensors 107, and adjust the radial position of the lower side of the rotor shaft 113 in the same manner as the radial position of the upper side.

[0026] Furthermore, axial electromagnets 106A and 106B are arranged above and below a circular metal disk 111 provided at the bottom of rotor shaft 113. Metal disk 111 is made of a highly magnetic permeable material such as iron. An axial sensor 109 is provided to detect the axial displacement of rotor shaft 113, and an axial position signal is sent to control device 200.

[0027] In the control device 200, a compensation circuit having, for example, a PID adjustment function generates excitation control command signals for the axial electromagnet 106A and the axial electromagnet 106B based on the axial position signal detected by the axial sensor 109, and the amplifier circuit 150 controls the excitation of the axial electromagnet 106A and the axial electromagnet 106B based on these excitation control command signals, so that the axial electromagnet 106A attracts the metal disc 111 upward by magnetic force, and the axial electromagnet 106B attracts the metal disc 111 downward, thereby adjusting the axial position of the rotor shaft 113.

[0028] In this way, the control device 200 appropriately adjusts the magnetic forces that the axial electromagnets 106A and 106B exert on the metal disk 111, magnetically levitating the rotor shaft 113 in the axial direction and holding it in space without contact. The amplifier circuit 150 that controls the excitation of the upper radial electromagnet 104, the lower radial electromagnet 105, and the axial electromagnets 106A and 106B will be described later.

[0029] Meanwhile, motor 121 has a plurality of magnetic poles arranged circumferentially so as to surround rotor shaft 113. Each magnetic pole is controlled by control device 200 so as to rotate rotor shaft 113 via electromagnetic force acting between the magnetic pole and rotor shaft 113. Motor 121 also incorporates a rotational speed sensor (not shown), such as a Hall element, resolver, or encoder, and the rotational speed of rotor shaft 113 is detected by the detection signal of this rotational speed sensor.

[0030] Furthermore, a phase sensor (not shown) is attached, for example, near the lower radial sensor 108, to detect the phase of rotation of the rotor shaft 113. The control device 200 uses the detection signals of both this phase sensor and the rotational speed sensor to detect the position of the magnetic pole.

[0031] A plurality of (three in this example) fixed vanes 123 (123a, 123b, 123c) are arranged with a small gap between them and the rotating vanes 102 (102a, 102b, 102c). Each of the rotating vanes 102 (102a, 102b, 102c) is formed at an angle at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 (as shown schematically in Figures 9(a) and 9(b)), in order to transport exhaust gas molecules downward through collision. The fixed vanes 123 (123a, 123b, 123c) are made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals as an ingredient.

[0032] Similarly, the fixed vanes 123 are formed so as to be inclined at a predetermined angle from a plane perpendicular to the axis of the rotor shaft 113 (by inclining a large number of fixed blades (reference numeral omitted)), and are arranged alternately with the rows of the rotor vanes 102 toward the inside of the case 130. The outer peripheral ends of the fixed vanes 123 are supported by being inserted between a plurality of stacked rows of fixed vane spacers 125 (125a, 125b).

[0033] Stator spacer 125 is a ring-shaped member made of metal such as aluminum, iron, stainless steel, copper, or an alloy containing any of these metals. An outer cylinder 127 is fixed to the outer periphery of stator spacer 125 with a small gap therebetween.

[0034] The base portion 129 is made of a metal such as iron, aluminum, stainless steel, etc. The base portion 129 not only physically holds the turbomolecular pump 100 but also functions as a heat conduction path, so it is desirable to use a metal that is rigid and has high thermal conductivity, such as iron, aluminum, or copper.

[0035] In this configuration, when the rotor 102 is rotated together with the rotor shaft 113 by the motor 121, the action of the rotor 102 and the stator 123 causes exhaust gas (here, mixed gas) to be drawn from the vacuum chamber into the first vacuum vessel 11. As will be described later, the drawn exhaust gas passes between the rotor 102 and the stator 123 and is transferred to the second vacuum vessel 12 by the exhaust action of the turbomolecular pump 100. At this time, the exhaust gas (mixed gas) is separated into its gas components, and this gas component separation action will be described later.

[0036] The temperature of the rotor 102 rises due to frictional heat generated when the exhaust gas comes into contact with the rotor 102 and conduction of heat generated by the motor 121, but this heat is transferred to the fixed blade 123 side by radiation or conduction through gas molecules in the exhaust gas.

[0037] The stator spacers 125 are joined together at their outer peripheries and transmit to the outside heat received by the stator 123 from the rotor 102 and frictional heat generated when exhaust gas comes into contact with the stator 123.

[0038] In addition, to prevent the gas introduced into the case 130 from entering the electrical equipment section, which is composed of the upper radial electromagnet 104, the upper radial sensor 107, the motor 121, the lower radial electromagnet 105, the lower radial sensor 108, the axial electromagnets 106A and 106B, the axial sensor 109, etc., the electrical equipment section is surrounded by a stator column 122, and the interior of this stator column 122 can be kept at a predetermined pressure by purge gas.

[0039] In this case, piping (purge gas introduction ports) is provided in the outer cylinder 127 and the base portion 129, and the purge gas is introduced through these piping. The introduced purge gas is sent to a predetermined exhaust port (not shown) through gaps between the protective bearing 120 and the rotor shaft 113, between the rotor and stator of the motor 121, and between the stator column 122 and the inner cylindrical portion of the rotor blades 102.

[0040] Here, the turbomolecular pump 100 requires control based on specific parameters (e.g., various characteristics corresponding to the model) that have been individually adjusted and identified for the model. To store these control parameters, the turbomolecular pump 100 is provided with an electronic circuit section 141 within its body. The electronic circuit section 141 is composed of a semiconductor memory such as an EEPROM, electronic components such as semiconductor elements for accessing the memory, and a substrate 143 for mounting these components. The electronic circuit section 141 is housed below a rotational speed sensor (not shown) near the center of a base section 129 that constitutes the lower part of the turbomolecular pump 100, and is closed by an airtight bottom lid 145.

[0041] Next, a description will be given of the amplifier circuit 150 that controls excitation of the upper radial electromagnets 104, the lower radial electromagnets 105, and the axial electromagnets 106A and 106B in the turbomolecular pump 100. A circuit diagram of this amplifier circuit 150 is shown in FIG.

[0042] 3, one end of the electromagnet winding 151 constituting the upper radial electromagnet 104 etc. is connected to a positive electrode 171a of a power supply 171 via a transistor 161, and the other end is connected to a negative electrode 171b of the power supply 171 via a current detection circuit 181 and a transistor 162. The transistors 161 and 162 are so-called power MOSFETs, and have a structure in which a diode is connected between the source and drain.

[0043] At this time, the transistor 161 has a diode cathode terminal 161a connected to the positive electrode 171a and an anode terminal 161b connected to one end of the electromagnet winding 151. The transistor 162 has a diode cathode terminal 162a connected to the current detection circuit 181 and an anode terminal 162b connected to the negative electrode 171b.

[0044] Meanwhile, current regeneration diode 165 has its cathode terminal 165a connected to one end of electromagnet winding 151 and its anode terminal 165b connected to negative electrode 171b. Similarly, current regeneration diode 166 has its cathode terminal 166a connected to positive electrode 171a and its anode terminal 166b connected to the other end of electromagnet winding 151 via current detection circuit 181. Current detection circuit 181 is configured, for example, with a Hall sensor type current sensor or an electrical resistance element.

[0045] The amplifier circuit 150 configured as above corresponds to one electromagnet. Therefore, if the magnetic bearing is controlled in five axes and there are a total of ten electromagnets 104, 105, 106A, and 106B, a similar amplifier circuit 150 is configured for each electromagnet, and the ten amplifier circuits 150 are connected in parallel to the power supply 171.

[0046] Furthermore, the amplifier control circuit 191 is configured, for example, by a digital signal processor section (hereinafter referred to as a DSP section) not shown in the figure of the control device 200, and this amplifier control circuit 191 is configured to switch the transistors 161 and 162 on / off.

[0047] The amplifier control circuit 191 compares the current value detected by the current detection circuit 181 (a signal reflecting this current value is called a current detection signal 191c) with a predetermined current command value. Based on the comparison result, the amplifier control circuit 191 determines the size of the pulse width (pulse width times Tp1 and Tp2) to be generated within a control cycle Ts, which is one period under PWM control. As a result, gate drive signals 191a and 191b having these pulse widths are output from the amplifier control circuit 191 to the gate terminals of the transistors 161 and 162.

[0048] It is necessary to control the position of rotor 103 at high speed and with strong force when, for example, the rotor 103 passes through a resonance point during acceleration of its rotational speed or when a disturbance occurs during constant-speed operation. For this reason, a high voltage of, for example, about 50 V is used as power supply 171 so that the current flowing through electromagnet winding 151 can be rapidly increased (or decreased). In addition, a capacitor (not shown) is usually connected between positive electrode 171a and negative electrode 171b of power supply 171 to stabilize power supply 171.

[0049] In this configuration, when both transistors 161 and 162 are turned on, the current flowing through the electromagnet winding 151 (hereinafter referred to as electromagnet current iL) increases, and when both are turned off, the electromagnet current iL decreases.

[0050] Furthermore, when one of the transistors 161 and 162 is turned on and the other is turned off, a so-called flywheel current is maintained. By passing a flywheel current through the amplifier circuit 150 in this manner, hysteresis loss in the amplifier circuit 150 can be reduced, and the power consumption of the entire circuit can be kept low. Furthermore, by controlling the transistors 161 and 162 in this manner, high-frequency noise such as harmonics generated in the turbomolecular pump 100 can be reduced. Furthermore, by measuring this flywheel current with the current detection circuit 181, the electromagnet current iL flowing through the electromagnet winding 151 can be detected.

[0051] That is, when the detected current value is smaller than the current command value, both transistors 161 and 162 are turned on for a time period corresponding to pulse width time Tp1 only once in a control cycle Ts (for example, 100 μs), as shown in Fig. 4. Therefore, during this period, the electromagnet current iL increases toward a current value iLmax (not shown) that can flow from the positive electrode 171a to the negative electrode 171b via the transistors 161 and 162.

[0052] On the other hand, if the detected current value is greater than the current command value, both transistors 161 and 162 are turned off for a time period corresponding to pulse width time Tp2 only once during control cycle Ts, as shown in Fig. 5. Therefore, the electromagnet current iL during this period decreases toward a current value iLmin (not shown) that can be regenerated from negative pole 171b to positive pole 171a via diodes 165 and 166.

[0053] In either case, after the pulse width times Tp1 and Tp2 have elapsed, one of the transistors 161 and 162 is turned on. Therefore, a flywheel current is maintained in the amplifier circuit 150 during this period.

[0054] The turbomolecular pump 100 is electrically (and structurally) connected to a box-shaped electrical equipment case (not shown), which incorporates the above-mentioned control device 200. The turbomolecular pump 100 and the case 130 which houses the first vacuum vessel 11 and the second vacuum vessel 12 can be used in an inverted, horizontal or inclined position in addition to the vertical position shown in Fig. 2.

[0055] The aforementioned protective bearings 120 are also called "touchdown (T / D) bearings" or "backup bearings." These protective bearings 120 prevent the position or attitude of the rotor shaft 113 from changing significantly, even in the unlikely event of a problem with the electrical system or atmospheric inrush, and prevent damage to the rotor blades 102 and their surrounding areas.

[0056] In the diagram (FIG. 2) showing the structure of the turbo molecular pump 100 and the like, hatching showing cross sections of components is omitted to avoid cluttering the drawing.

[0057] Next, the operation of the rare gas recovery system 10 in this embodiment will be described based on the diagram in Figure 6. Figure 6 shows the operations related to each process of rare gas recovery from top to bottom. Also, in Figure 6, to the right of the "Operation" section, an item "Valve Status" is shown. This "Valve Status" section indicates the open / closed states of the first valve 14, the second valve 16, and the third valve 18. Furthermore, in Figure 6, the first valve 14 is represented by the symbol "A," the second valve 16 is represented by the symbol "B," and the third valve 18 is represented by the symbol "C."

[0058] First, the turbo molecular pump 100 operates to evacuate the first vacuum chamber 11 and the second vacuum chamber 12 (operation indicated by No. 1 in the diagram). Hereinafter, the operations indicated by No. 1 to No. 7 in Fig. 6 may be referred to as "first operation" to "seventh operation."

[0059] In the first operation, designated No. 1 in Figure 6, the first valve 14 (designated "A") and the second valve 16 (designated "B") are open, and the third valve 18 (designated "C") is closed. In Figure 6, an open valve is designated "open," and a closed valve is designated "closed."

[0060] In this first operation, evacuation is performed with the third valve 18 connected to the gas inlet 131 closed and the first valve 14 connected to the first vacuum vessel 11 and the second valve 16 connected to the second vacuum vessel 12 both open. As a result, the pressure inside the first vacuum vessel 11 and the second vacuum vessel 12 drops, and the first vacuum vessel 11 and the second vacuum vessel 12 become empty, with the gas molecules inside having been exhausted.

[0061] Subsequently, in a second operation, the first valve 14 (symbol "A") and the second valve 16 (symbol "B") are closed, and in a third operation, the third valve 18 is opened. As a result, the mixed gas is introduced into the first vacuum vessel 11, and via the evacuation action of the turbomolecular pump 100, the mixed gas is also introduced into the second vacuum vessel 12. In this embodiment, the mixed gas used contains 50% helium (He) gas and 50% argon (Ar) gas.

[0062] In the first vacuum vessel 11, the internal gas pressure (Pa) gradually decreases due to the evacuation action of the turbo molecular pump 100. In the second vacuum vessel 12, the internal gas pressure (Pb) gradually increases as the mixed gas is introduced.

[0063] When the pressure Pb inside the second vacuum vessel 12 reaches a predetermined pressure (here, Pb = 300 mT (millitorr)), the third valve 18 (valve C) is closed (fourth operation). Furthermore, in a fifth operation, the first valve 14 (valve A) is opened. As will be described later, He gas is selectively stored in the first vacuum vessel 11, and when the first valve 14 (valve A) is opened, the He gas inside the first vacuum vessel 11 is discharged to the outside of the first vacuum vessel 11.

[0064] After He is exhausted from the first vacuum vessel 11, the first valve 14 (valve A) is open, and the second valve 16 (valve B) and the third valve 18 (valve C) are closed, and evacuation by the turbomolecular pump 100 continues. When the pressure Pa in the first vacuum vessel 11 reaches a predetermined pressure (here, Pa = 1 mT), the second valve 16 (valve B) is opened (sixth operation).

[0065] As will be described later, Kr gas is selectively stored in the second vacuum vessel 12, and when the second valve 16 (valve B) is opened, the Kr gas in the second vacuum vessel 12 is discharged to the outside of the second vacuum vessel 12. After this, the above-mentioned first to sixth operations are repeated (herein referred to as the "seventh operation"), and the He gas and Kr gas are separated, discharged, and recovered.

[0066] Generally, when pumping with a turbomolecular pump, the larger the mass of the molecule (atom in the case of a single element), the larger the compression ratio. As in this embodiment, when a mixed gas of Kr (molecular weight of approximately 83.8) and He (molecular weight of approximately 4.0) is pumped by the turbomolecular pump 100 (with three stages of rotor blades 102 and three stages of stator blades 123), the compression ratio of Kr is 605, and the compression ratio of He is 5.

[0067] Therefore, the ratio of the amount of Kr in the first vacuum vessel 11 to the amount of Kr in the second vacuum vessel 12 is 1:605, and theoretically, more than 99% (=(605 / 606)×100) of the Kr is collected in the second vacuum vessel 12.

[0068] On the other hand, the ratio of the amount of He in the first vacuum vessel 11 to the amount of He in the second vacuum vessel 12 is 1:5, and approximately 83% (=(5 / 6)×100) of the He is collected in the second vacuum vessel 12.

[0069] During the fifth operation described above, even after evacuation of He has begun, He will remain in the second vacuum vessel 12 at a ratio that depends on the compression ratio, which will be described later. However, due to the evacuation action of the turbomolecular pump 100 and the backflow of He, He will move to the first vacuum vessel 11 in proportion to the compression ratio. Therefore, after the fifth operation is performed, by the time the pressure Pa in the first vacuum vessel 11 reaches 1 mT, which is the starting condition for the sixth operation, most of the He will be in the first vacuum vessel 11.

[0070] 7 shows simulation results for the partial pressures in the first vacuum vessel 11 and the second vacuum vessel 12 at the start of the fifth operation and the start of the sixth operation. At the start of the fifth operation, the partial pressures of the gas species (gas components) in the first vacuum vessel 11 were 23.5 mT for He and 0.27 mT for Kr. In other words, He was approximately 99% (= 23.5 / (23.5 + 0.27) × 100), and Kr was approximately 1% (= 0.27 / (23.5 + 0.27) × 100).

[0071] The partial pressure of each gas component in the second vacuum vessel 12 was 136.5 mT (approximately 46%=136.5 / 300×100) for He and 163.5 mT (approximately 54%=163.5 / 300×100) for Kr.

[0072] As described above, in the fifth operation, the first vacuum vessel 11 is opened. Therefore, during the fifth operation, He gas is exhausted from the first vacuum vessel 11, which stores approximately 99% of the He gas. After this, the first vacuum vessel 11 remains open and the turbo molecular pump 100 continues to exhaust the He gas, separating it in accordance with the compression ratio and discharging it from the first vacuum vessel 11.

[0073] Then, the pressure (Pa) in the first vacuum vessel 11 reaches 1 mT, which is the starting condition for the sixth operation, and when the sixth operation is started, the partial pressures of the gas components in the first vacuum vessel 11 are He 0.75 mT (75% = 0.75 / 1 × 100) and Kr 0.25 mT (25% = 0.25 / 1 × 100).

[0074] The partial pressure of each gas component in the second vacuum vessel 12 was 4.0 mT for He (approximately 2%=4.0 / (4.00+163.0)×100) and 163.0 mT for Kr (approximately 98%=163.0 / (4.00+163.0)×100).

[0075] As described above, the second vacuum vessel 12 is opened in the sixth operation. Therefore, during the sixth operation, approximately 98% of the Kr gas is exhausted from the second vacuum vessel 12 in which it is stored. Therefore, according to the rare gas recovery system 10 of this embodiment, it is possible to recover nearly 100% of the Kr gas. Furthermore, with the second vacuum vessel 12 open, exhaust by the turbomolecular pump 100 continues, and separation of the Kr gas according to the compression ratio and exhaust from the second vacuum vessel 12 continue.

[0076] FIG. 8(a) shows the simulation results of the pressure change after the first valve 14 is opened and evacuation of He from the first vacuum vessel 11 is initiated in the fifth operation (FIG. 6). In FIG. 8(a), the horizontal axis represents elapsed time (s (seconds)), and the vertical axis represents the partial pressure of each gas (mTorr (mT)). Furthermore, He in the first vacuum vessel 11 is represented by the symbol "He1," and Kr in the first vacuum vessel 11 is represented by the symbol "Kr1." Furthermore, He in the second vacuum vessel 12 is represented by the symbol "He2," and Kr in the second vacuum vessel 12 is represented by the symbol "Kr2."

[0077] 8(a), as the first valve 14 is opened, the partial pressure of He1 (He gas in the first vacuum vessel 11) gradually decreases from a value exceeding 20 mT (23.5 mT as described above) and approaches 0 mT after about 160 seconds have passed. Furthermore, as described above, the proportion of Kr1 (Kr gas in the first vacuum vessel 11) is small at about 1%, and therefore shows a value close to 0 mT from the beginning when the first valve 14 is opened.

[0078] On the other hand, since the second valve 16 of the second vacuum vessel 12 is closed, Kr2 (Kr gas in the second vacuum vessel 12) continues to show a constant value. However, He2 (He gas in the second vacuum vessel 12) drops rapidly as the first valve 14 is opened, approaching 0 mT after about 200 seconds. The reason why the He gas (He2) in the second vacuum vessel 12 drops as the first valve 14 connected to the first vacuum vessel 11 is opened is because, as mentioned above, a backflow of He occurs from the second vacuum vessel 12 to the first vacuum vessel 11.

[0079] Figure 8(b) shows the relationship between the content of He gas (He1) in the first vacuum vessel 11 and the content of Kr gas (Kr2) in the second vacuum vessel 12 for the fifth operation (Figure 6). In Figure 8(b), the horizontal axis represents the elapsed time (s (seconds)), and the vertical axis represents the content (%) of each gas.

[0080] 8(b), as the first valve 14 is opened, the content of He1 (He gas in the first vacuum vessel 11) gradually decreases from a value close to 100% (approximately 99%) and reaches approximately 80% after 220 seconds. In contrast, the content of Kr2 (Kr gas in the second vacuum vessel 12) gradually increases from a value exceeding 50% (approximately 54%) and reaches 90% after 150 seconds. Then, after 220 seconds, Kr2 exceeds 95% and reaches nearly 100%.

[0081] The reason for the change in partial pressure as shown in Figure 8(a) and the change in content as shown in Figure 8(b) can also be explained as follows. Figures 9(a) and 9(b) show the relationship between the movement of gas molecules and the rotating impeller 102. Individual gas molecules contained in the mixed gas introduced into the first vacuum vessel 11 move freely within the first vacuum vessel 11. Gas molecules that move toward the rotating impeller 102 may collide with and bounce off the rotating blades (rotating blades 132 shown schematically in Figures 9(a) and 9(b)), pass through between the rotating blades 132, or flow back from the second vacuum vessel 12 to the first vacuum vessel 11.

[0082] The average molecular velocity of gas molecules can generally be calculated using the following formula: V=(8RT / πM)1 / 2 According to this formula, for example, the average molecular velocity of He and Kr is as follows: He at 300K: V = 1,260 m / s Kr at 300K: V=275m / s Here, R is the gas constant, T is the absolute temperature, π is the ratio of the circumference of a circle to its diameter, and M is the molecular weight of the gas. In this way, when the molecular weight of the gas molecules is small, the average molecular motion velocity is large, and when the molecular weight of the gas molecules is large, the average molecular motion velocity is small.

[0083] In this embodiment, the inclination angle of the rotary blades 132 (FIGS. 9(a) and 9(b)) of the rotary blades 102 and the rotational speed (circumferential speed) of the rotary blades 102 are designed taking into consideration the molecular weight and average molecular motion speed of the gas molecules to be recovered. In FIGS. 9(a) and 9(b), the relationship between the rotary blades 132 that move in the circumferential direction as the rotary blades 102 rotate and the incidence angle (average incidence angle) of He and Kr with respect to the rotary blades 102 is shown using a vector diagram related to velocity vectors.

[0084] In FIGS. 9(a) and 9(b), the rotational velocity vector of the rotor 102 is denoted by V A The average molecular velocity vector of the gas molecules is denoted by V B , V C The rotation direction of the rotor 102 is indicated by an arrow D, and the rotation velocity vector V A The direction (positive direction) is set opposite to the direction of rotation of the rotor 102.

[0085] Average molecular velocity vector V B , V C The direction (positive direction) of the rotational velocity vector V is set to the direction when looking from the first vacuum vessel 11 side to the second vacuum vessel 12 side. A and the average molecular velocity vector V B , V C The directions of the rotational velocity vector V are perpendicular to each other.A and the average molecular velocity vector V B , V C The resultant vectors of these are the incident vectors V of the gas molecules incident on the rotor 102. AB , V AC It is as follows.

[0086] The rotational velocity vector V shown in Figure 9(a) A and the incident vector V of He AB The angle θ1 between the rotor blades 102 and the rotational velocity vector V A and the Kr incident vector V AC The angle θ2 between these is the angle of incidence of Kr with respect to the rotor 102. As described above, the average molecular velocity of He (1,260 m / s in this case) is greater than the average molecular velocity of Kr (275 m / s in this case), and therefore the angle of incidence θ1 of He is greater than the angle of incidence θ2 of Kr.

[0087] The tilt angle (elevation angle) θ3 of the rotary blade 132 of the rotary wing 102 is the angle between a virtual reference line L set in the rotation direction (direction of arrow D) of the rotary wing 102 and a surface (rear surface) 133 of the rotary blade 132 facing the first vacuum vessel 11, as depicted in a cross section. The elevation angle θ3 of the rotary blade 132 is set to be smaller than the incident angle θ1 of He. Furthermore, the elevation angle θ3 of the rotary blade 132 is set to be equivalent to the incident angle θ2 of Kr. Here, "equivalent" can be exemplified by setting the difference between the elevation angle θ3 of the rotary blade 132 and the incident angle θ2 of Kr to, for example, within ±10 degrees, preferably within ±5 degrees, and more preferably 0 degrees.

[0088] Because the elevation angle θ3 of the rotating blade 132 is smaller than the incident angle θ1 of He, He incident on the rotating blade 102 is likely to strike the back surface 133 of the rotating blade 132 and bounce (fly) upstream. On the other hand, because the elevation angle θ3 of the rotating blade 132 is equal to the incident angle θ2 of Kr, Kr incident on the rotating blade 102 is unlikely to strike the back surface 133 of the rotating blade 132. For this reason, Kr passes through the rotating blade 102 and is likely to reach the second vacuum vessel 12 from the first vacuum vessel 11.

[0089] As mentioned above, since the average moving speed of Kr is 275 m / s, for example, when the circumferential speed of the rotating blades 132 is 350 m / s, the elevation angle θ3 is set to Tan-1(275 / 350) = 38 degrees. By doing so, the inclination angle θ3 of the rotating blades 132 and the incident angle θ2 of Kr become the same. This makes it possible to significantly reduce the exhaust efficiency of He compared to Kr.

[0090] Furthermore, Kr can be pumped efficiently, and the compression ratio can be significantly improved compared to He. As a result, Kr is selectively pumped by the turbomolecular pump 100, and the compression ratio of Kr (605 in this case) is significantly higher than the compression ratio of He (5 in this case). As a result, changes in partial pressure as shown in Figure 8(a) and changes in content as shown in Figure 8(b) are observed.

[0091] Here, the relationship between the elapsed time and the partial pressure of each gas shown in Figure 8(a) and the relationship between the elapsed time and the content shown in Figure 8(a) can vary depending on various conditions such as the timing of opening and closing each valve 14, 16, and 18, the rotation speed of the rotor 102, the elevation angle θ3 of the rotor blade 132, and the shapes of the rotor 102 and the fixed blade 123.

[0092] According to the rare gas recovery system 10 as described above, a turbomolecular pump 100, a first vacuum vessel 11 arranged upstream of the turbomolecular pump 100, and a second vacuum vessel 12 arranged downstream of the turbomolecular pump are used to separate rare gases by utilizing the exhaust action of the turbomolecular pump 100 and the differences in the properties of the gas components.

[0093] Therefore, it is possible to separate gases without using a refrigerator to cool the cold trap or raising and lowering the temperature of the cold trap as described in the above-mentioned Patent Document 1. Therefore, expensive rare gases such as Kr can be recovered easily and at low cost. Furthermore, rare gases can be recovered without consuming a large amount of energy.

[0094] Furthermore, according to the rare gas recovery system 10, rare gases can be separated by utilizing the difference in compression ratio of the turbomolecular pump 100 for each gas component. Therefore, it is possible to separate rare gases with a compact configuration without using a large device.

[0095] Here, in order to efficiently separate gases using the turbomolecular pump 100, it is desirable that the difference in compression ratios between the gas components be large. Furthermore, the inventors have found that as the number of blade stages increases, the compression ratio of each gas component increases, as shown in Figure 10. Figure 10 shows the compression ratios of He and Kr when the number of blade stages is changed. In Figure 10, the number of blade stages is set to 4, 6, and 8.

[0096] The "number of blade stages" here is a numerical value obtained by adding the number of stages (number of stacked stages) of the rotor blades 102 and the number of stages (number of stacked stages) of the fixed blades 123. For example, when the "number of blade stages" is four, it means that the number of stages of the rotor blades 102 and the number of stages of the fixed blades 123 are both two. When the "number of blade stages" is six, it means that the number of stages of the rotor blades 102 and the number of stages of the fixed blades 123 are each three, and when it is eight, it means that the number of stages of the rotor blades 102 and the number of stages of the fixed blades 123 are each four.

[0097] As a result of simulations by the inventors, when the number of blade stages was four, the compression ratio of He was about 3, and the compression ratio of Kr was about 50. When the number of blade stages was six, the compression ratio of He was about 5, and the compression ratio of Kr was about 600. When the number of blade stages was eight, the compression ratio of He was about 9, and the compression ratio of Kr was about 10,000. Note that in the turbomolecular pump 100 of the embodiment described above, the number of blade stages was six (three stages each of the rotor blades 102 and the stator blades 123), and the explanation was given assuming that the compression ratio of He was 5 and the compression ratio of Kr was 605 (≈600).

[0098] In order to effectively utilize the backflow from the second vacuum vessel 12 to the first vacuum vessel 11, it is considered desirable to set the compression ratio of at least one gas component with a relatively small compression ratio (a gas component with a relatively small molecular weight) to, for example, 20 or less. In the above-described embodiment, the compression ratio of He, which has a relatively small compression ratio, is 5 (≦20), which satisfies this condition. Furthermore, according to the rare gas recovery system 10, by setting an appropriate number of stages of blades (rotating blades 102 and fixed blades 123) in the turbomolecular pump 100, it is possible to appropriately set the difference in compression ratio.

[0099] Here, the "number of blade stages" is the sum of the rotor blades 102 and the fixed blades 123, but even if only one of the blade stages is used, it can be explained that increasing the number of blade stages increases the compression ratio.

[0100] Furthermore, the means for setting the compression ratio of at least one specific gas component to a target value (here, a low value of 20 or less) is not limited to the number of blade stages, and it is also possible to use, for example, the rotational speed (number of revolutions) of the turbomolecular pump 100.

[0101] 9(a) and 9(b), the rotational speed of the turbomolecular pump 100 (the rotational speed of the rotor 102) affects the angle of incidence of gas molecules onto the rotor blades 132. Therefore, the rotational speed of the turbomolecular pump 100 is also a factor that determines the compression ratio. Therefore, by appropriately setting the rotational speed of the turbomolecular pump 100, it is possible to set the compression ratio of a specific gas component to a target value (here, 20 or less).

[0102] By setting the rotation speed of the turbo molecular pump 100 low, the angles of incidence θ1 and θ2 of the gas components onto the rotary blades 132 become large, making it possible to further reduce the compression ratio of He.

[0103] Furthermore, for example, the control device 200 can be set to at least two rotational speeds (for example, a circumferential speed of 400 m / s or more and 350 m / s or less), and by lowering the rotational speed from a relatively high speed, the gas components in the mixed gas can be separated at an appropriate rotational speed. In this way, it becomes possible to recover the rare gas more efficiently.

[0104] Furthermore, according to the rare gas recovery system 10 of this embodiment, the average molecular velocity vector V of a gas component (e.g., Kr) having a relatively large molecular weight among the mixed gas components introduced from the gas inlet 131 is C and the circumferential velocity of the rotor 102, and the angle of elevation (θ3) of at least one of the rotor 102 and the fixed blade 123 (for example, the rotor 102) is set equal to the average angle of incidence (θ2). This makes it possible to efficiently separate and recover gas.

[0105] Furthermore, according to the rare gas recovery system 10 of this embodiment, the case 130 of the turbo molecular pump 100 is used to form the first vacuum vessel 11 and the second vacuum vessel 12. The first vacuum vessel 11 and the second vacuum vessel 12 are configured inside the case 130 of the turbo molecular pump 100. Therefore, the rare gas recovery system 10 does not become large-scale, and it is easy to make the rare gas recovery system 10 compact.

[0106] 6, the timing for closing the third valve 18 in the fourth operation is when the pressure Pb in the second vacuum vessel 12 reaches 300 mTorr (mT). In addition, when evacuating Kr from the second vacuum vessel 12 in the sixth operation, the timing for opening the second valve 16 is when the pressure Pa in the first vacuum vessel 11 reaches 1 mTorr (mT). However, this is not limitative and other timings may be used.

[0107] For example, when it is desired to recover Kr at a higher concentration, the timing of opening the second valve 16 can be set later than the timing at which the pressure Pb in the second vacuum vessel 12 reaches 1 mT. Also, when the allowable value set as the concentration of the rare gas to be recovered is relatively low, it is also possible to open the second valve 16 earlier than the timing at which the pressure Pb in the second vacuum vessel 12 reaches 1 mT.

[0108] 2, the first vacuum vessel 11 is provided with the gas inlet ports 131 and 13a, and the mixed gas is introduced into the first vacuum vessel 11. The turbomolecular pump 100 exhausts gas from the first vacuum vessel 11 side to the second vacuum vessel 12 side. However, in the rare gas recovery system 10 and the rare gas recovery method of the present invention, the turbomolecular pump 100 allows gas to flow backward. Therefore, for example, the mixed gas may be introduced into the second vacuum vessel 12, and the turbomolecular pump 100 may exhaust gas from the second vacuum vessel 12 side to the first vacuum vessel 11 side.

[0109] In addition, the rare gas is not limited to He or Kr, and other types of rare gases can be used. In addition, the components of the mixed gas (mixed gas components) are not limited to the combination of He and Kr, and other combinations may be used.

[0110] Furthermore, the number of components in the mixed gas is not limited to two, and may be three or more. When the mixed gas has three or more components, for example, after recovering one type of gas, the rotation speed of the turbo molecular pump 100 can be reduced, and the gas components with small molecular weights in the remaining mixed gas can be caused to flow back from the second vacuum vessel 12 to the first vacuum vessel 11, and the gases can be recovered sequentially.

[0111] Specifically, for example, when three types of gases, gas A, gas B, and gas C, are mixed and the molecular weights of gas A are smaller than gas B and gas C in that order, the gases are exhausted in the following order (1) to (3). (1) The turbo molecular pump 100 is operated at high speed (high speed operation) to exhaust the gas A from the first vacuum vessel 11. At this time, the gases B and C are confined in the second vacuum vessel 12. (2) The rotation speed of the turbo molecular pump 100 is reduced to cause the gas B to flow backward into the first vacuum vessel 11, and the gas B is exhausted from the first vacuum vessel 11. (3) The gas C remaining in the second vacuum vessel 12 is exhausted from the second vacuum vessel 12.

[0112] Furthermore, it is also possible to connect a plurality of cases 130 each having a turbomolecular pump 100, a first vacuum vessel 11, and a second vacuum vessel 12, thereby forming a multi-stage rare gas recovery system.

[0113] Furthermore, in order to bring the concentration of the recovered rare gas closer to 100%, it is possible to introduce the rare gas that has been recovered once (for example, at a concentration of 99%) back into the first vacuum vessel 11 in the case 130 and separate the rare gas using the turbomolecular pump 100. As described above, it is also possible to connect multiple cases 130 each having a turbomolecular pump 100, first vacuum vessel 11, and second vacuum vessel 12 to form a multiple-stage rare gas recovery system, thereby increasing the concentration of the recovered rare gas.

[0114] Furthermore, in order to change the compression ratio, it is also possible to replace the rotor 102 and the stator 123 of the turbomolecular pump 100 with ones having different shapes.

[0115] The present invention is not limited to the above-described embodiments, and many modifications can be made by those skilled in the art using their ordinary creative abilities within the scope of the technical concept of the present invention. [Explanation of symbols]

[0116] 10 Rare Gas Recovery System 11 1st vacuum container (1st vacuum chamber) 12 Second vacuum container (second vacuum chamber) 14 First valve 16 Second valve 100 Turbomolecular Pump 102 Rotor 123 Fixed wing 130 Case (Casing) 131 Gas inlet 132 Rotating Blade 134 First gas outlet 136 Second gas outlet

Claims

1. A turbomolecular pump in which rotors and fixed blades are stacked alternately; a first vacuum chamber disposed upstream of the turbomolecular pump; a second vacuum chamber disposed downstream of the turbomolecular pump; a first gas exhaust port disposed in the first vacuum chamber; a second gas exhaust port disposed in the second vacuum chamber; a gas inlet disposed in one of the first vacuum chamber or the second vacuum chamber; a first valve disposed in the first gas exhaust port and capable of exhausting gas from within the first vacuum chamber; a second valve disposed in the second gas exhaust port and capable of exhausting gas from within the second vacuum chamber; a third valve disposed at the gas inlet and capable of introducing a mixed gas containing a plurality of types of rare gases as gas components into one of the first vacuum chamber or the second vacuum chamber, a rare gas recovery system that operates the turbomolecular pump and changes a combination of opening and closing of the first valve, the second valve, and the third valve in a time series to separate and recover the gas components of the mixed gas, closing the first valve and the second valve and opening the third valve to introduce the mixed gas into the first vacuum chamber or the second vacuum chamber; Next, the third valve is closed, Next, the first valve is opened to exhaust the gas components in the first vacuum chamber from the first vacuum chamber; Subsequently, the second valve is opened to discharge the gas component in the second vacuum chamber from the second vacuum chamber.

2. With respect to an average incidence angle calculated from an average molecular velocity of a gas component with a large molecular weight among the mixed gas introduced from the gas inlet and a circumferential velocity of the rotor blade, 2. The rare gas recovery system according to claim 1, wherein the elevation angles of at least one of the rotary blades and the fixed blades of the turbomolecular pump are matched within ±10 degrees.

3. 3. The rare gas recovery system according to claim 1, wherein the first vacuum chamber and the second vacuum chamber are configured within a casing of the turbomolecular pump.

4. the turbomolecular pump is configured to be able to be set to at least two different rotation speeds; 4. The rare gas recovery system according to claim 1, wherein the system is configured so that several types of gases can be separated by lowering the rotation speed from a relatively high rotation speed.

5. A turbomolecular pump in which rotors and fixed blades are stacked alternately; a first vacuum chamber disposed upstream of the turbomolecular pump; a second vacuum chamber disposed downstream of the turbomolecular pump; a first gas exhaust port disposed in the first vacuum chamber; a second gas exhaust port disposed in the second vacuum chamber; a gas inlet disposed in one of the first vacuum chamber or the second vacuum chamber; a first valve disposed in the first gas exhaust port and capable of exhausting gas from within the first vacuum chamber; a second valve disposed in the second gas exhaust port and capable of exhausting gas from within the second vacuum chamber; a third valve disposed at the gas inlet and capable of introducing a mixed gas containing a plurality of types of rare gases as gas components into one of the first vacuum chamber or the second vacuum chamber, a rare gas recovery method for separating and recovering the gas components of the mixed gas by operating the turbomolecular pump and changing a combination of opening and closing of the first valve, the second valve, and the third valve in a time series, the method comprising: closing the first valve and the second valve and opening the third valve to introduce the mixed gas into the first vacuum chamber or the second vacuum chamber; Next, the third valve is closed, Next, the first valve is opened to exhaust the gas components in the first vacuum chamber from the first vacuum chamber; Subsequently, the second valve is opened to discharge the gas component in the second vacuum chamber from the second vacuum chamber.

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