Gas detection device and detection method based on absorbed electron energy

Abstract

The invention discloses a gas detection device and method based on absorbed electron energy, and belongs to the technical field of gas sensing and detection. According to the method, electrons emitted by an electron emission source enter a gas chamber containing mixed gas to be detected, the gas absorbs the electrons with specific energy, particles at a lower energy level jump to an upper energy level, the absorbed specific electron energy is used for marking the gas, and the gas concentration is reversely deduced according to the energy variation. The method has the remarkable advantages that the electron energy is used for exciting the gas to complete the transition of the gas energy level, different energy electrons emitted by the electron emission source have continuity, the change of the current representation number corresponds to the change of the electron energy absorbed by the gas, and the gas is distinguished according to the difference of the absorbed electron energy.

Description

Technical Field

[0001] The invention relates to a gas detection device and a detection method based on absorbing electron energy, belonging to the technical field of gas sensing and detection. Background Art

[0002] Real-time detection of gas types and contents is widely used in many key areas of society, such as food and drug safety, fire prevention, environmental monitoring, and medical care. People's needs have evolved from the initial basic detection level to the pursuit of higher sensitivity, better cost-effectiveness, and simpler operation.

[0003] At present, the mainstream gas analysis technologies include electrochemical sensors, pyroelectric sensors, semiconductor metal oxide sensors and optical sensors. However, these technologies have certain limitations due to their working principles. Electrochemical sensors have a short service life due to their detection principles. Gas sensors based on absorption spectroscopy have strict requirements on the selection of lasers. Each gas needs to select a laser with a different wavelength according to its absorption spectrum. Therefore, developing an innovative gas analysis technology has extremely important practical application value. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a gas detection device and a detection method based on absorbing electron energy to expand the current gas detection method.

[0005] The technical solution of the present invention is as follows:

[0006] A gas detection device based on absorbing electron energy includes an electron emission source, a gas chamber, a power supply, an electron collector, and an ammeter. The electron emission source is used to emit electrons, the gas chamber is filled with a gas to be detected, the power supply provides energy for the electrons, and the electron collector is used to collect electrons passing through the gas chamber. The electron emission source and the electron collector are placed on both sides of the gas chamber, the electron collector is connected to the ammeter, and the ammeter number shows the situation of collecting electrons.

[0007] The electrode plate is placed in the gas chamber near the electron collector, and the power supply is placed outside the gas chamber; one end of power supply A is connected to the electrode plate, and the other end is grounded; one end of power supply B is connected to the electrode plate, and the other end is connected to the ammeter; power supply A provides a forward acceleration voltage for electrons, and power supply B provides a reverse deceleration voltage for electrons; power supply B returns electrons with insufficient energy; electrons that are not returned reach the electron collector and pass through the ammeter, and different types of gases and concentrations are distinguished according to the changes in the current readings.

[0008] A detection method of a gas detection device based on absorbing electron energy, the steps comprising:

[0009] (1) Inject the gas to be tested into the gas chamber;

[0010] (2) The electron emission source emits electrons, and power source A provides an accelerating electric field to accelerate the electrons, and the voltage changes slowly from low to high; the electrons that gain energy collide with gas molecules or atoms, and the kinetic energy is transferred to the gas molecules or atoms, and the gas molecules or atoms transition from a lower energy level to another higher energy level; the electrons lose part of their kinetic energy after the collision, and if the remaining energy is large enough, it can overcome the reverse voltage of power source B, reach the electron collector, and become the current passing through the ammeter; if the remaining energy is not enough to overcome the reverse voltage of power source B, it is returned, and the change in the ammeter is recorded;

[0011] Preferably, the voltage value of power source B is fixed, the voltage of power source A is increased from 0, and data is recorded when the ammeter shows a reading. It is observed that as the voltage increases, the ammeter reading shows a periodic oscillation and rise phenomenon, that is, a periodic oscillation rise that first increases and then decreases, and then increases again and then decreases;

[0012] Adjust the intensity of the accelerating electric field. The change process from elastic collision to inelastic collision between electrons and atoms will be reflected in the electric current. Observe and record the data changes.

[0013] (3) By comparing the current changes of different gases, the gas type and gas concentration are identified according to the location of the current change, the drop point and the drop amplitude.

[0014] For different gases, the energy required for each gas to undergo energy level transition is different, and the current representation curve obtained in the experiment is different. The gas type is distinguished according to the descending point of the curve.

[0015] Preferably, in step (3), the voltage difference between the first peak and the second peak is calculated, and the gas with the corresponding energy difference is searched in the database based on the voltage difference.

[0016] Preferably, in step (3), the gas concentration is calculated according to the degree of descent of the descending section, and calibration is first performed using a gas of known concentration, and the gas concentration value C can be calculated by substituting the following formula into the gas concentration value C;

[0017] C=k*(C std / k std )(1)

[0018] Where C is the gas concentration to be measured, k is the signal slope measured at this concentration, and C std is the concentration of the standard gas used for calibration, k std It is the signal slope obtained under standard gas concentration. The signal slope is the slope of a descending segment, or the signal slope is the average of the slopes of multiple descending segments.

[0019] Further preferably, in step (3), the signal slope is the average of the slopes of the three groups of descending segments, and the signal slope is calculated by the following formula group:

[0020] k1=(I a -I b ) / (V a -V b )(2)

[0021] k2=(I c -I d ) / (V c -V d )(3)

[0022] k3=(I e -I f ) / (V e -V f )(4)

[0023] k avg =(k1+k2+k3) / 3(5)

[0024] a is the first peak point, V a ,I a is the voltage and current value of this point, b is the first valley point, V b ,I b is the voltage and current value of this point, c is the second peak point, V c ,I c is the voltage and current value of this point, d is the second valley point, V d ,I d is the voltage and current value of this point, e is the third peak point, V e ,I e is the voltage and current value of this point, f is the third valley point, V f ,I f are the voltage and current values ​​at that point, k and k std All are obtained through formula (2)-(5) and finally by formula (5).

[0025] The beneficial effects of the present invention are:

[0026] The present invention introduces electrons with varying accelerating voltages to cause gas molecules or atoms to transition from lower energy levels to upper energy levels through inelastic collisions, and energy is transferred. The current indication number reflects the energy required for energy level transition, and the gas composition and concentration are inferred based on the change in the indication number, making the adjustment more sensitive, the detection more accurate, and the efficiency higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the detection method of the present invention;

[0028] In the figure: 1-electron emission source, 2-power supply A, 3-gas chamber, 4-power supply B, 5-electron collector, 6-ammeter;

[0029] Figure 2 Schematic diagram of energy level transition of neon atoms absorbing electron energy when injected by an electron emission source in Example 1 of the present invention;

[0030] Figure 3 It is a schematic diagram of current change, with the ordinate being the current value and the abscissa being the voltage value. DETAILED DESCRIPTION

[0031] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0032] like Figure 1-3 shown.

[0033] Embodiment 1:

[0034] A gas detection device based on absorbing electron energy, the structure of which is as follows Figure 1 As shown, it includes an electron emission source, a gas chamber, a power supply, an electron collector, and an ammeter. The electron emission source is used to emit electrons, the gas to be tested is filled in the gas chamber, the power supply provides energy for the electrons, and the electron collector is used to collect electrons passing through the gas chamber. The electron emission source and the electron collector are placed on both sides of the gas chamber, and the electron collector is connected to the ammeter. The ammeter shows the situation of collecting electrons.

[0035] The electrode plate is placed in the gas chamber near the electron collector, and the power supply is placed outside the gas chamber; one end of power supply A is connected to the electrode plate, and the other end is grounded; one end of power supply B is connected to the electrode plate, and the other end is connected to the ammeter. Power supply A provides a forward acceleration voltage for electrons, and power supply B provides a reverse deceleration voltage for electrons. Power supply B returns electrons with insufficient energy; the electrons that are not returned reach the electron collector and pass through the ammeter, and different types of gases and concentrations are distinguished according to the changes in the current indication number.

[0036] Embodiment 2:

[0037] A detection method of a gas detection device based on absorbing electron energy, wherein the device structure is as described in Example 1, wherein an electron emission source emits electrons, and power supply A provides an acceleration voltage for the electrons; power supply B returns electrons with insufficient energy; electrons that are not returned reach an electron collector, which is connected to an ammeter, and different types of gases and concentrations are distinguished according to changes in the current indication number.

[0038] The gas detection method for absorbing electron energy provided by the present invention comprises: Figure 1 The system implementation shown, taking neon gas as an example, the specific steps are as follows:

[0039] (1) Connect the above system and inject neon gas into the gas chamber;

[0040] (2) Turn on the power of the electron emission source, electron collector, and ammeter, turn on power supplies A and B, slowly adjust the voltage of power supply A, fix the voltage of power supply B at 0.5 V, increase the voltage of power supply A from 0, and start recording data when the ammeter shows a number. It is observed that as the voltage increases, the ammeter readings show a periodic oscillation and rise, that is, it increases first and then decreases, increases again and then decreases, and then shows a periodic oscillation and rise, such as Figure 3 As shown. The electrons emitted by the electron emission source are accelerated by the accelerating electric field of the forward voltage of power source A to gain more and more kinetic energy, and collide with neon gas to exchange energy. When the voltage of power source A is lower than 16.8V, the collision between electrons and neon atoms is a completely elastic collision, and the neon atoms remain in the ground state; when the voltage is greater than or equal to 16.8V, the collision between electrons and neon atoms produces an inelastic collision, and the neon atoms obtain enough energy to transition from the ground state to the first excited state.

[0041] After the accelerated electron collides with the neon atom, it continues to move forward and is decelerated by the deceleration electric field of the reverse voltage of power supply B. Only kinetic energy can overcome the reverse voltage (0.5V, Figure 3 Only electrons with kinetic energy lower than this value can reach the electron collector and form current. Figure 3 When the medium voltage is 0-0.5V, the corresponding current is 0.

[0042] Power supply A voltage is greater than 0.5V (V o ) and less than 16.8V(V a ), the electron kinetic energy is small, and the collision with the neon atom is a completely elastic collision. After overcoming the reverse voltage, it reaches the electron collector and forms a current, corresponding to the oa curve in the figure. At this time, the current increases with the increase of voltage. When the voltage of power supply A is greater than or equal to 16.8V (V a ) and less than 17.3V(V b ), the collision between electrons and neon atoms occurs inelastic collision, and the electrons transfer energy to the neon atoms, so that the neon atoms gain enough energy to transition from the ground state to the nearest higher energy state. After these electrons give energy to the neon atoms, they do not have enough energy to overcome the reverse voltage of power supply B to reach the electron collector, and the current reading decreases, corresponding to the ab segment in the figure. Similarly, continue to increase the voltage, and when it is less than 33.6V (V c) Before the current increases with the increase of voltage, it corresponds to the bc segment in the figure. When the voltage is greater than 33.6V, the electrons and neon atoms have a second inelastic collision, transferring energy to the atoms for energy level transition, and cannot reach the electron collector, causing the current reading to drop for the second time, corresponding to the cd segment in the figure. Adjust the acceleration electric field strength, and the change process from elastic collision to inelastic collision between electrons and atoms will be shown in the current. Observe and record the data changes, and identify the gas type and gas concentration according to the location of the current change, the drop point and the drop amplitude.

[0043] (3) By comparing the current changes of different gases, the gas type and gas concentration are identified according to the location of the current change, the drop point and the drop amplitude.

[0044] For different gases, there are different high-energy excited states, and the energy required to transition from the ground state to the excited state will be different. The corresponding V a With V c The voltage difference will be different. According to this voltage difference, the gas with the corresponding energy difference can be found in the database (NIST Atomic Spectra Database, HITRAN Database) to identify the gas type. The higher the gas concentration, the more gas particles there will be, the greater the probability of collision with electrons, the more electrons will lose energy during collision, and the greater the slope of the descending section (such as ab, cd, ef sections). The gas concentration is calculated based on the degree of decline. In practical applications, it is necessary to calibrate with a gas of known concentration first, and then substitute it into the following formula to calculate the gas concentration value C.

[0045] C=k*(C std / k std )(1)

[0046] Where C is the gas concentration to be measured, k is the signal slope measured at this concentration, and C std is the concentration of the standard gas used for calibration, k std is the signal slope obtained under the standard gas concentration. The signal slope is calculated by the following formula group:

[0047] k1=(I a -I b ) / (V a -V b )(2)

[0048] k2=(I c -I d ) / (V c -V d )(3)

[0049] k3=(I e -I f) / (V e -V f )(4)

[0050] k avg =(k1+k2+k3) / 3(5)

[0051] k vs k std All are obtained through formula (2)-(5) and finally by formula (5).

[0052] The signal slope may be the slope of a descending segment, or may be the average of the slopes of multiple descending segments. In this embodiment, the average of the slopes of three descending segments is taken.

Claims

1. A gas detection device based on absorbing electron energy, characterized in that: It includes an electron emission source, a gas chamber, a power supply, an electron collector, and an ammeter. The electron emission source is used to emit electrons. The gas chamber is filled with a gas to be tested. The power supply provides energy for the electrons. The electron collector is used to collect electrons passing through the gas chamber. The electron emission source and the electron collector are placed on both sides of the gas chamber. The electron collector is connected to the ammeter, and the ammeter shows the situation of collecting electrons. The electrode plate is placed in the gas chamber near the electron collector, and the power supply is placed outside the gas chamber; one end of power supply A is connected to the electrode plate, and the other end is grounded; one end of power supply B is connected to the electrode plate, and the other end is connected to the ammeter; power supply A provides a forward acceleration voltage for electrons, and power supply B provides a reverse deceleration voltage for electrons; power supply B returns electrons with insufficient energy; electrons that are not returned reach the electron collector and pass through the ammeter.

2. A detection method of a gas detection device based on absorbing electron energy, wherein the device is as described in claim 1, characterized in that: The steps include: (1) Inject the gas to be tested into the gas chamber; (2) The electron emission source emits electrons, and power source A provides an accelerating electric field to accelerate the electrons, and the voltage changes from low to high; the electrons that gain energy collide with gas molecules or atoms, and the kinetic energy is transferred to the gas molecules or atoms, and the gas molecules or atoms transition from a lower energy level to another higher energy level; the electrons lose part of their kinetic energy after the collision, and if the remaining energy is large enough, it can overcome the reverse voltage of power source B, reach the electron collector, and become the current passing through the ammeter; if the remaining energy is not enough to overcome the reverse voltage of power source B, it is returned, and the change in the ammeter is recorded; (3) By comparing the current changes of different gases, the gas type and gas concentration are identified according to the location of the current change, the drop point and the drop amplitude.

3. The detection method of the gas detection device based on absorbing electron energy according to claim 2, characterized in that: In step (2), the voltage value of power source B is fixed, and the voltage of power source A is increased from 0. When the current meter shows a reading, data is recorded. It is observed that as the voltage increases, the current meter reading shows a periodic oscillation and rise phenomenon. Adjust the intensity of the accelerating electric field. The change process from elastic collision to inelastic collision between electrons and atoms will be reflected in the electric current. Observe and record the data changes.

4. The detection method of the gas detection device based on absorbing electron energy according to claim 2, characterized in that: In step (3), the voltage difference between the first peak and the second peak is calculated, and the gas corresponding to the energy difference is searched in the database based on the voltage difference.

5. The detection method of the gas detection device based on absorbing electron energy according to claim 2, characterized in that: In step (3), the gas concentration is calculated according to the degree of descent in the descending section. The gas concentration value C is calculated by first calibrating with a gas of known concentration and then substituting it into the following formula; C=k*(C std / k std )(1) Where C is the gas concentration to be measured, k is the signal slope measured at this concentration, and C std is the concentration of the standard gas used for calibration, k std It is the signal slope obtained under standard gas concentration. The signal slope is the slope of a descending segment, or the signal slope is the average of the slopes of multiple descending segments.

6. The detection method of the gas detection device based on absorbing electron energy according to claim 5, characterized in that: In step (3), the signal slope is the average of the slopes of the three groups of descending segments, and the signal slope is calculated by the following formula group: k1=(I a -AND b ) / (V a -V b )(2) k2=(I c -I d ) / (V c -V d )(3) k3=(I e -I f ) / (V e -V f )(4) k avg =(k1+k2+k3) / 3(5) a is the first peak point, V a ,I a is the voltage and current value of this point, b is the first valley point, V b ,I b is the voltage and current value of this point, c is the second peak point, V c ,I c is the voltage and current value of this point, d is the second valley point, V d ,I d is the voltage and current value of this point, e is the third peak point, V e ,I e is the voltage and current value of this point, f is the third valley point, V f ,I f are the voltage and current values ​​at that point, k and k std All are obtained through formula (2)-(5) and finally by formula (5).

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