Vacuum protection device for mass spectrometer

Abstract

The utility model discloses a vacuum protection device for a mass spectrometer, which comprises a vacuum cavity and a protection circuit, the vacuum cavity is connected with a plurality of molecular pumps through a connecting cavity, the vacuum cavity is connected with a first vacuum gauge and a second vacuum gauge, and the vacuum cavity is connected with a mechanical pump close to a sample inlet. The molecular pump, the first vacuum gauge and the second vacuum gauge are connected with the protection circuit through lines. According to the utility model, the protection circuit is adopted to protect the molecular pump, and the protection circuit uses the linear relation characteristic of the output voltage and the vacuum degree of the vacuum gauge to turn off the molecular pump under the condition that the vacuum is abnormal, so that the molecular pump is prevented from being damaged when running under low vacuum.

Description

Technical Field

[0001] The utility model relates to the field of mass spectrometers, in particular to a vacuum protection device for a mass spectrometer. Background Art

[0002] A mass spectrometer, also known as a mass spectrometer, is an instrument that separates and detects different isotopes. It is an instrument that separates and detects the composition of matter according to the mass differences of atoms, molecules or molecular fragments of a substance based on the principle that charged particles can be deflected in an electromagnetic field.

[0003] The vacuum degree of the mass spectrometer is an important factor affecting the movement rate of ions. Insufficient vacuum can easily lead to collisions between ions and gas molecules, thereby reducing the movement rate of ions. The impact on the correspondence between the electrical signals of the mass analyzer and the electrical signals of the detector is mainly reflected in the time correspondence and other aspects, thereby affecting the mass accuracy. At the same time, abnormal vacuum will also cause changes in the movement rate of ions, and will also affect the resolution of the mass spectrometer and the service life of the molecular pump. Summary of the invention

[0004] The purpose of the utility model is to address the deficiencies of the above-mentioned prior art and to provide a vacuum protection device for a mass spectrometer, which can shut down the molecular pump in the event of vacuum abnormality, thereby preventing the molecular pump from being damaged when operating under low vacuum.

[0005] The technical solution adopted by the utility model is as follows:

[0006] A vacuum protection device for a mass spectrometer comprises a vacuum cavity and a protection circuit. The vacuum cavity is connected to a plurality of molecular pumps via a connecting cavity, the vacuum cavity is connected to a first vacuum gauge and a second vacuum gauge, a mechanical pump is connected to the vacuum cavity near an injection port, and the molecular pump, the first vacuum gauge and the second vacuum gauge are connected to the protection circuit via a line.

[0007] Preferably, the protection circuit includes a first operational amplifier, a second operational amplifier, a first resistor, a second resistor and a NAND gate, the output end of the first vacuum gauge is connected to the input end of the first resistor through a line, and the output end of the first resistor is connected to the negative input end of the first operational amplifier through a line; the output end of the second vacuum gauge is connected to the input end of the second resistor through a line, and the output end of the second resistor is connected to the negative input end of the second operational amplifier through a line, the output ends of the first operational amplifier and the second operational amplifier are both connected to the input end of the NAND gate through a line, and the output end of the NAND gate is connected to the input end of the molecular pump through a line.

[0008] Preferably, the positive input terminal of the first operational amplifier is connected to the first reference voltage through a line, and a third resistor is connected in parallel between the positive input terminal and the output terminal of the first operational amplifier.

[0009] Preferably, the positive input terminal of the second operational amplifier is connected to the second reference voltage through a line, and a fourth resistor is connected in parallel between the positive input terminal and the output terminal of the second operational amplifier.

[0010] Preferably, the model of the first vacuum gauge is TTR911.

[0011] Preferably, the model of the second vacuum gauge is PTR225.

[0012] Preferably, the output terminal voltage range of the first vacuum gauge and the second vacuum gauge is 0-5V.

[0013] Preferably, the vacuum chamber is made of aluminum.

[0014] Preferably, the vacuum chamber is connected to two molecular pumps via a connecting chamber.

[0015] The utility model has the following beneficial effects: the utility model adopts a protection circuit to protect the molecular pump, and the protection circuit uses the linear relationship between the output voltage of the vacuum gauge and the vacuum degree to shut down the molecular pump when an abnormal vacuum occurs, thereby preventing the molecular pump from being damaged when operating under low vacuum. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the utility model;

[0017] Figure 2 It is a schematic diagram of the protection circuit in the utility model;

[0018] In the figure, 1, vacuum chamber; 2, molecular pump; 3, first vacuum gauge; 4, second vacuum gauge; 5, mechanical pump; 6, protection circuit. DETAILED DESCRIPTION

[0019] The utility model is further described below in conjunction with the accompanying drawings:

[0020] like Figure 1-2 As shown, the utility model is a vacuum protection device for a mass spectrometer, comprising a vacuum cavity 1 made of aluminum and a protection circuit 6. The vacuum cavity 1 is connected to a plurality of molecular pumps 2 through a connecting cavity, preferably two molecular pumps 2; the vacuum cavity 1 is connected to a first vacuum gauge 3 of model TTR911 and a second vacuum gauge 4 of model PTR225, wherein TTR911 is a Piranin vacuum gauge of Leybold Company, suitable for low vacuum measurement, and the measurement range is 5*10 -5 To 1000 mbar, which meets the low vacuum measurement requirements of mass spectrometers; PTR225 is a cold cathode vacuum gauge from Leybold, suitable for high vacuum measurement, with a measurement range of 10 -8 Up to 5*10 -3mbar, which meets the high vacuum measurement requirements of the mass spectrometer. The vacuum chamber 1 is connected to a mechanical pump 5 near the injection port. The mechanical pump 5 is responsible for providing a rough vacuum and drawing the vacuum near the injection port to 0.9Pa-1.1Pa. The two molecular pumps 2 are responsible for increasing the vacuum degree. When the two molecular pumps 2 work normally, they can maintain the vacuum at 10 -4 Pa around.

[0021] The two molecular pumps 2, the first vacuum gauge 3 and the second vacuum gauge 4 in the utility model are connected to the protection circuit 6 through a line; the protection circuit 6 uses the linear relationship between the output voltage and the vacuum degree of the first vacuum gauge 3 and the second vacuum gauge 4 to shut down the two molecular pumps 2 when an abnormal vacuum occurs, thereby preventing the two molecular pumps 2 from being damaged when operating under a low vacuum.

[0022] The protection circuit 6 in the utility model includes a first operational amplifier, a second operational amplifier, a first resistor, a second resistor and a NAND gate. The output end of the first vacuum gauge 3 is connected to the input end of the first resistor through a line, and the output end of the first resistor is connected to the negative input end of the first operational amplifier through a line; the output end of the second vacuum gauge 4 is connected to the input end of the second resistor through a line, and the output end of the second resistor is connected to the negative input end of the second operational amplifier through a line. The output ends of the first operational amplifier and the second operational amplifier are both connected to the input end of the NAND gate through a line, and the output end of the NAND gate is connected to the input end of the molecular pump 2 through a line. The positive input end of the first operational amplifier is connected to the first reference voltage through a line, and a third resistor is connected in parallel between the positive input end and the output end of the first operational amplifier. The positive input end of the second operational amplifier is connected to the second reference voltage through a line, and a fourth resistor is connected in parallel between the positive input end and the output end of the second operational amplifier. The output voltage range of the first vacuum gauge 3 and the second vacuum gauge 4 is 0-5V, the protection circuit 6 adopts a rail-to-rail operational amplifier (the first operational amplifier and the second operational amplifier) ​​of model AD8648, and a hysteresis comparison circuit composed of operational amplifiers is input to the first vacuum gauge 3 and the second vacuum gauge 4; the output results of the two hysteresis comparison circuits pass through a NAND gate, and the output signal of the NAND gate is used as the start and stop signal to control the two molecular pumps 2. A high level indicates opening, and a low level indicates closing.

[0023] The use process of the utility model is as follows:

[0024] When in use, the staff first manually turns on the mechanical pump 5 and the first vacuum gauge 3, and when the vacuum value of the first vacuum gauge 3 reaches 1Pa, turns on the second vacuum gauge 4 and the two molecular pumps 2; when the vacuum chamber 1 gradually enters the working state, the protection circuit 6 takes effect, and uses the linear relationship between the output voltage and vacuum degree of the first vacuum gauge 3 and the second vacuum gauge 4 to shut down the two molecular pumps 2 in the event of vacuum abnormality, thereby preventing the two molecular pumps 2 from running under low vacuum and causing damage to them.

[0025] When the staff needs to close the vacuum chamber 1 , they first turn off the two molecular pumps 2 , then turn off the second vacuum gauge 4 , and finally turn off the first vacuum gauge 3 and the mechanical pump 5 .

[0026] Other unexplained parts of the present invention are the same as those of the prior art.

Claims

1. A vacuum protection device for a mass spectrometer, characterized in that The invention comprises a vacuum chamber (1) and a protection circuit (6); the vacuum chamber (1) is connected to a plurality of molecular pumps (2) via a connecting chamber; the vacuum chamber (1) is connected to a first vacuum gauge (3) and a second vacuum gauge (4); a mechanical pump (5) is connected to the vacuum chamber (1) near a sampling port; and the molecular pump (2), the first vacuum gauge (3) and the second vacuum gauge (4) are connected to the protection circuit (6) via a line.

2. The vacuum protection device for a mass spectrometer according to claim 1, characterized in that The protection circuit (6) comprises a first operational amplifier, a second operational amplifier, a first resistor, a second resistor and a NAND gate, wherein the output end of the first vacuum gauge (3) is connected to the input end of the first resistor via a line, and the output end of the first resistor is connected to the negative input end of the first operational amplifier via a line; the output end of the second vacuum gauge (4) is connected to the input end of the second resistor via a line, and the output end of the second resistor is connected to the negative input end of the second operational amplifier via a line, the output ends of the first operational amplifier and the second operational amplifier are both connected to the input end of the NAND gate via a line, and the output end of the NAND gate is connected to the input end of the molecular pump (2) via a line.

3. The vacuum protection device for mass spectrometer according to claim 2, characterized in that The positive input terminal of the first operational amplifier is connected to a first reference voltage through a line, and a third resistor is connected in parallel between the positive input terminal and the output terminal of the first operational amplifier.

4. The vacuum protection device for a mass spectrometer according to claim 3, characterized in that The positive input terminal of the second operational amplifier is connected to the second reference voltage through a line, and a fourth resistor is connected in parallel between the positive input terminal and the output terminal of the second operational amplifier.

5. The vacuum protection device for mass spectrometer according to claim 1, characterized in that The model of the first vacuum gauge (3) is TTR911.

6. The vacuum protection device for mass spectrometer according to claim 1, characterized in that The model of the second vacuum gauge (4) is PTR225.

7. The vacuum protection device for a mass spectrometer according to claim 5 or 6, characterized in that The output terminal voltage range of the first vacuum gauge (3) and the second vacuum gauge (4) is 0-5V.

8. The vacuum protection device for a mass spectrometer according to claim 1, characterized in that The vacuum chamber (1) is made of aluminum.

9. The vacuum protection device for a mass spectrometer according to claim 1, characterized in that The vacuum chamber (1) is connected to two molecular pumps (2) via a connecting chamber.

Images