JP4655738B2 - Charged particle amount evaluation apparatus and charged particle amount evaluation method - Google Patents

Description

  The present invention relates to a charged particle amount evaluation apparatus and a charged particle amount evaluation method for evaluating the particle size, the number of particles, and the like of fine particles floating in the atmosphere.

  This kind of charged particle quantity evaluation apparatus is a differential type electric mobility measuring device (DMA: Differential) that measures the particle size of fine particles by utilizing the difference in the moving speed (electric mobility) of charged fine particles in an electric field. Mobility Analyzer) has been conventionally provided (see, for example, Patent Document 1).

  However, since the charged particle amount evaluation apparatus using DMA is large, a charged particle amount evaluation apparatus using a double concentric cylinder called a Gel Dien capacitor has been conventionally provided (for example, see Non-Patent Document 1). FIG. 7 is a schematic configuration diagram of a charged particle amount evaluation apparatus 1 using a gel diene capacitor. The charged particle amount evaluation apparatus 1 includes a concentric cylindrical electrode 2, an intake fan 3, an ammeter 4, a voltage source. 5 as a main configuration.

  The concentric cylindrical electrode 2 is configured by concentrically arranging cylindrical inner conductors 2a and outer conductors 2b having different radii. In the double concentric cylinder, a DC voltage is applied to the outer conductor 2b by the voltage source 5, and the inner conductor 2a is grounded. The voltage source 5 can change the power supply voltage by a voltage control unit (not shown).

  The intake fan 3 sucks air through the space between the inner conductor 2a and the outer conductor 2b, thereby causing air to flow in the direction of the arrow A through the space between the inner conductor 2a and the outer conductor 2b. A laminar flow with uniform flow direction and velocity is generated.

  The ammeter 4 measures the current flowing between the inner conductor 2a and the outer conductor 2b, and the number of charged particles can be calculated from the current value.

  In this apparatus, when air is sucked by the intake fan 3, the inner conductor 2a is grounded, and a voltage V is applied to the outer conductor 2b by the voltage source 5 to give a potential difference between the inner and outer conductors. Charged particles in the air sucked between the conductors are attracted to the inner conductor 2a by an electric field generated between the two conductors. When the charged particles flow into the inner conductor 2a, a current is generated between the two conductors, so that the number of charged particles can be measured based on the measured value of the ammeter 4. In addition, if the polarity of the voltage V applied by the voltage source 5 and the polarity of the measured value of the ammeter 4 are taken into account, charged particles having either positive or negative polarity can be measured.

Here, the particle size of the charged particles depends on the mobility, and the mobility is determined by making the size of the double cylinder (inner conductor 2a and outer conductor 2b) and the air flow rate constant, the applied voltage of the voltage source 5. Determined by V. Therefore, by changing the applied voltage of the voltage source 5 and measuring the current value with the ammeter 4, the number of charged particles having a predetermined particle diameter can be obtained. However, in the measuring apparatus of FIG. 7 using a double concentric cylinder called a gel diene capacitor, all charged particles having a mobility (particle diameter) or less determined by the applied voltage of the voltage source 5 are taken in and all the particles are evaluated. Yes.
Japanese Patent Laid-Open No. 10-288600 Edited by Shinichiro Kitagawa, “Atmospheric Electricals”, Tokai University Press, June 10, 1996, pp. 47-49

  In the charged particle amount evaluation apparatus having the above configuration, the distribution of the number of particles is obtained by measuring the number of charged particles in a predetermined particle size range based on the change in mobility. Since the number of charged particles having a particle size smaller than that of the particles is integrated and measured, the distribution of the number of particles has a plurality of maximum points P1 and P2 within the particle size measurement range as shown in FIG. If the number of charged particles is measured in the vicinity of the maximum point P2 having a large particle diameter, the charged particles near the maximum point P1 having a small particle diameter are obtained by integration, resulting in a decrease in the S / N ratio. There are problems that the measurement accuracy is lowered and the reproducibility is deteriorated.

  The present invention has been made in view of the above problems, and the object of the present invention is to provide a highly reproducible amount of charged particles even when charged particles having a plurality of particle size peaks are released from a charged particle source. An object of the present invention is to provide a charged particle amount evaluation apparatus and a charged particle amount evaluation method that can be evaluated with high accuracy.

In order to achieve the above object, the invention of claim 1 includes a first concentric cylindrical electrode formed by concentrically arranging cylindrical first inner conductors and first outer conductors having different radii, An airflow generating means for generating an airflow along an axial direction in an annular space between one inner conductor and a first outer conductor, and a direct current voltage applied to both the first inner conductor and the first outer conductor. A first voltage applying terminal for measuring the current, a current measuring terminal for measuring the current flowing between the first inner conductor and the first outer conductor, and the outside of the first concentric cylindrical electrode A second space is applied to the upstream side of the air flow, and a voltage is applied by the filter electrode to generate an electric field that prevents charged particles having a particle size equal to or smaller than a predetermined threshold from flowing into the annular space. Voltage application terminal is provided Rutotomoni a filter electrode, a voltage control means for adjusting the first and second voltage applied by the voltage source respectively for applying a respective DC voltage to said first and second voltage applying terminal, connected to the current measuring terminal Current value acquisition means for acquiring the measured value of the current measurement means, and the current value acquired by the current value acquisition means when the voltage control means sweeps the voltage applied by the first voltage source in a predetermined voltage range. Based on the threshold value acquired by the removed particle size acquisition means and the removal particle size acquisition means for acquiring the second largest particle size among the particle sizes when A removal voltage calculation means for calculating a voltage value for generating an electric field that does not allow charged particles to flow into the annular space, and the voltage control means calculates the voltage applied by the second voltage source by the removal voltage calculation means. Shi And controlling the voltage value.

According to the present invention, a voltage is applied to the filter electrode via the second voltage application terminal, and the particle size is equal to or smaller than a predetermined threshold in the external space of the first concentric cylindrical electrode and upstream of the airflow. Since the electric field that prevents the charged particles from flowing into the annular space of the concentric cylindrical electrode is generated, when measuring the number of charged particles having a particle size larger than the threshold, the number of charged particles below the threshold is integrated. Therefore, there is an effect that it is possible to realize a charged particle amount evaluation apparatus with high measurement accuracy and good reproducibility. In addition, the removal particle size acquisition means automatically sweeps the voltage applied by the first voltage source within a predetermined voltage range by the voltage control means, and the current value acquired by the current value acquisition means during this time is maximized. The second largest particle size of the particle sizes is acquired as the threshold value, and the voltage value applied to the filter electrode by the removal voltage calculation means is calculated based on this threshold value. Even when the diameter is unknown, the particle size of the charged particles to be removed can be automatically set, and the charged particle amount can be evaluated with high measurement accuracy. For example, if there are five maximum values of the number of particles, and you want to measure the number of particles with the particle size corresponding to the fourth maximum value from the smaller particle size, the fourth maximum value from the smaller one If the applied voltage is set so that the particle size becomes the maximum value in the particle size measurement range, the particle size corresponding to the third maximum value from the smallest value is set as the threshold value. The maximum value can be set as a threshold, and the number of particles having a desired particle diameter can be measured.

  According to a second aspect of the present invention, in the first aspect, the filter electrode is a second concentric cylindrical electrode configured by concentrically arranging cylindrical second inner conductors and second outer conductors having different radii. It is characterized by comprising.

  According to the present invention, by configuring the filter electrode with a concentric cylindrical electrode, the charged particles to be removed are attracted to the inner conductor or the outer conductor and removed as an electric current. It is possible to improve the measurement accuracy by removing it without leaving it, and it is possible to accurately detect the spatial distribution of charged particles. In addition, by making the shape of the filter electrode the same as that of the first concentric cylindrical electrode, turbulence occurs when the airflow passing through the second concentric cylindrical electrode flows into the first concentric cylindrical electrode. Measurement accuracy can be improved by allowing the charged particles to flow into the first concentric cylindrical electrode in a state where the influence of the number of charged particles on the particle size distribution is reduced.

  According to a third aspect of the present invention, in the second aspect of the invention, the first inner conductor and the second inner conductor, and the first outer conductor and the second outer conductor are formed to have substantially the same radius. The second concentric cylindrical electrodes are connected to each other via an insulating member at the upstream end of the first concentric cylindrical electrode in a state where the respective inner conductors and outer conductors are overlapped. And

  According to the present invention, the first inner conductor and the second inner conductor, and the first outer conductor and the second outer conductor are formed with substantially the same radius, and the first and second concentric cylindrical electrodes are Since the inner conductor and the outer conductor are overlapped and connected via the insulating member, there is no discontinuous point in the connecting portion, and the air flow passes through the second concentric cylindrical electrode. There is an effect that it is possible to further prevent the airflow from being disturbed when flowing into the concentric cylindrical electrode.

In the invention of claim 4 , a DC voltage is applied between the two conductors of the concentric cylindrical electrode formed by concentrically arranging the cylindrical first inner conductor and the first outer conductor having different radii. A charged particle amount evaluation that generates an airflow that flows along the axial direction in the annular space of the battery and causes charged particles to flow in the annular space between the two conductors by the airflow, and evaluates the amount of charged particles from the current value of the current flowing between the two conductors. This method measures the particle size distribution of the number of charged particles flowing between the two conductors, and obtains the second largest particle size as the threshold value for removing the particle size from the maximum particle number. Then, an applied voltage set based on the threshold is applied to a filter electrode disposed outside the concentric cylindrical electrode and upstream of the air flow, and charged particles having a particle size equal to or smaller than the threshold are applied to both conductors. An electric field that does not flow into the annular space is generated In condition, and measuring the particle size distribution of number of particles of charged particles flowing between the two conductors again.

  According to this invention, the particle size distribution of the number of charged particles flowing between the two conductors is measured, and the second largest particle size among the particle sizes at which the number of particles becomes a maximum is to be removed. Since the particle size of the charged particles to be removed is unknown, the particle size of the charged particles to be removed can be automatically acquired, and the outer space of the concentric cylindrical electrode An applied voltage set based on the above threshold is applied to the filter electrode placed on the upstream side of the airflow to generate an electric field that prevents charged particles with a particle size below the above threshold from flowing into the annular space between the two conductors. In this state, since the particle size distribution of the number of charged particles flowing between the two conductors is measured again, when measuring the number of charged particles having a particle size larger than the threshold, the number of charged particles below the threshold Charging with high measurement accuracy and good reproducibility. There is an effect that it provides a molecular weight evaluation method.

  According to the first aspect of the present invention, the second voltage applying means applies a voltage to the filter electrode, and the particle size is equal to or smaller than a predetermined threshold in the external space of the first concentric cylindrical electrode and upstream of the airflow. Since the electric field that prevents the charged particles from flowing into the annular space of the concentric cylindrical electrode is generated, when measuring the number of charged particles having a particle size larger than the threshold, the number of charged particles below the threshold is integrated. Therefore, there is an effect that it is possible to realize a charged particle amount evaluation apparatus with high measurement accuracy and good reproducibility.

According to the invention of claim 4 , since the second largest particle size among the maximum particle size is acquired as the threshold value of the particle size to be removed, the particle size of the charged particles to be removed is unknown However, the particle size of the charged particles to be removed can be automatically acquired, and the filter electrode disposed outside the concentric cylindrical electrode and upstream of the airflow is set based on the above threshold value. When the applied voltage is applied and an electric field is generated so that charged particles having a particle size equal to or smaller than the threshold value do not flow into the annular space between the two conductors, the particle size of the number of charged particles flowing between the two conductors Since the distribution is measured again, charging with high measurement accuracy and good reproducibility without measuring the number of charged particles below the threshold when integrating the number of charged particles with a particle size larger than the threshold There is an effect that a particle amount evaluation method can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
Embodiment 1 of a charged particle amount evaluation apparatus using a charged particle amount evaluation method according to the present invention will be described with reference to FIGS.

  The charged particle amount evaluation apparatus 1 according to the present embodiment includes a first concentric cylindrical electrode (hereinafter abbreviated as a concentric cylindrical electrode) 2, an intake fan 3 serving as an air flow generating means, an ammeter 4, and a first voltage. A power source (hereinafter abbreviated as a voltage source) 5, a filter electrode 6, a second voltage source (hereinafter abbreviated as a voltage source) 7, an insulating member 8, and a controller 10 are provided as main components.

  The concentric cylindrical electrode 2 is configured by concentrically arranging cylindrical first inner conductors 2a (hereinafter abbreviated as inner conductors) and first outer conductors (hereinafter abbreviated as outer conductors) 2b having different radii. . The inner conductor 2a and the outer conductor 2b are preferably formed of a material having high conductivity so that the charged particles can be easily attracted and the current flowing between the two conductors can be easily measured. It is formed.

  The inner conductor 2 a is not hollow but includes a ground terminal 21 and a current measurement terminal 22, and is grounded to the ground via a ground line 25 connected to the ground terminal 21. The inner conductor 2a is held in the outer conductor 2b via a holding member (not shown) having a high insulating property in order to prevent an error from being caused by charging and current flowing. As a material for the holding member, it is preferable to use, for example, a highly insulating ethylene trifluoride chloride resin.

  The outer conductor 2 b has a hollow cylindrical shape and includes a voltage terminal 23 and a current measurement terminal 24, and a DC voltage of the voltage source 5 is applied through the voltage terminal 23. An ammeter 4 is connected between the current measurement terminal 22 of the inner conductor 2a and the current measurement terminal 24 of the outer conductor 2b. Here, the ground terminal 21 of the inner conductor 2a and the voltage terminal 23 of the outer conductor 2b constitute a first voltage application terminal.

  Here, the relationship between the particle diameter and mobility of the charged particles, the applied voltage applied to the outer conductor 2b, and the outer dimensions of the concentric cylindrical conductor 2 will be described with reference to FIG.

  Assuming that charged particles in the air have equal mobility, ions flowing from the point P at the edge of the outer conductor 2b on the intake side of the concentric cylindrical conductor 2 receive an electric field between the conductors 2a and 2b. Assuming that the particles are captured at the point S, all the charged particles flowing into the cylinder of the concentric cylindrical conductor 2 are captured by the inner conductor 2a. The position of the point S where the charged particles are captured changes by adjusting the voltage applied to the outer conductor 2b and the flow rate of the airflow.

  By the way, charged particles having various mobilities exist in the actual air, and flow from the point P under a certain applied voltage and flow rate, and at the edge T on the outlet side of the inner conductor 2a. The mobility of charged particles to be trapped is called critical mobility. This critical mobility indicates a boundary between charged particles that can be captured by the inner conductor 2a and charged particles that cannot be captured by the inner conductor 2a, and all charged particles having a mobility higher than the critical mobility are captured by the inner conductor 2a. However, a part of the charged particles whose mobility is lower than the critical mobility is not captured and flows out from the outlet of the concentric cylindrical conductor 2 to the outside.

  For example, if the charged particles flowing from the point R in FIG. 7 are captured at the point T, the charged particles having the same mobility and charged from the region between the concentric circle C1 passing through the point R and the outer conductor 2b. The particles flow out from the outlet of the concentric cylindrical conductor 2, and only the charged particles flowing in from the region between the concentric circle C1 and the inner conductor 2a (hatched portion in the figure) are captured by the inner conductor 2a. .

  Here, the critical mobility kc of the charged particles is expressed by the following equation (1) when the voltage applied to the outer conductor 2b is V and the flow rate of the airflow is φ.

kc = φ × ln (r0 / r1) / (2π × L × V) (1)
Here, r0 is the radius of the outer conductor 2b, r1 is the radius of the inner conductor 2a, and L is the total axial length of the concentric cylindrical conductor 2. The relationship between the mobility kc and the particle size Dp of the charged particles is expressed by the following formula (2).

kc = np × e × Cc / (3π × μ × Dp) (2)
Where np is the number of charged particles, e is the elementary charge, Cc is the Cunningham correction coefficient, and μ is the viscosity coefficient of air. Further, the Cunningham correction coefficient Cc is a function of the particle diameter Dp, and the critical mobility kc, the particle diameter Dp, and the applied voltage V can be obtained by simultaneous equations (1) and (2). When determining the relationship between the particle size Dp and the applied voltage V, the Cunningham correction coefficient Cc changes depending on the particle size Dp, and therefore, the critical mobility kc is eliminated by simultaneous equations (1) and (2). Calculate numerically from the formula.

The size of the concentric cylindrical conductor 2 (full length L and radii r0, r1) is also determined by the equations (1) and (2), and the size of the concentric cylindrical conductor 2 is determined by the particle size to be measured. In the evaluation apparatus 1 of the present embodiment, as shown in FIG. 3A, the particle size measurement range is 0.6 to 28 nm, and the particle size peak is between 10 nm and 20 nm, for example, 14 nm. 3A and 3B, the horizontal axis indicates the particle size, and the vertical axis indicates the number of particles per unit volume. Here, assuming that the number np of charged particles is 1, the electric mobility is 5.49 to 0.000274 cm ² / V · s from the equation (2). Further, when the flow rate φ is 50 L / min and the applied voltage V is 0 to 60 V, the total length L of the concentric cylindrical conductor 2 is 52 cm, the radius r1 of the inner conductor 2 a is 4.5 cm, and the radius of the outer conductor 2 b from Equation (1). r0 is 4.8 cm. The conductor 2b has a thickness of 2 mm.

Further, the size of the filter electrode 6 is determined by the particle size range of the charged particles to be removed, but in order to prevent the airflow generated by the intake fan 3 from being disturbed as much as possible, the inner conductor of the concentric cylindrical conductor 2 is used. 2a and the outer conductor 2b, and the radius of the inner conductor 6a and the outer conductor 6b of the filter electrode 6 are set to be substantially the same value, so that the connecting portion between the concentric cylindrical conductor 2 and the filter electrode 6 is not uneven. It is preferable to do this. Here, when the range of the particle size to be removed is set to 2 nm or less, the mobility of the charged particle having a particle size of 2 nm is 0.514 cm ² / V · s from the above equation (2). However, the flow rate φ was 50 L / min, similar to the concentric cylindrical conductor 2, and the length of the filter electrode 6 was 8.0 cm. The radii of the inner conductor 6a and the outer conductor 6b are set to substantially the same values as the radii of the inner conductor 2a and the outer conductor 2b of the concentric cylindrical conductor 2, and the radius of the inner conductor 6a is 4.5 cm. Since the radius is 4.8 cm and the thickness is 2 mm, the applied voltage is 2.08 V from the above equation (1).

  On the other hand, the intake fan 3 is disposed on the airflow outlet side (right side in FIG. 1) with respect to the concentric cylindrical electrode 2 and sucks air in the annular space 2c between the inner conductor 2a and the outer conductor 2b. The airflow that flows along the axial direction is generated in the annular space 2c. The rotational speed of the intake fan 3 is kept constant, and the flow rate of the airflow is kept constant. Here, in order to generate a laminar flow in the space (annular space 2c) between the two conductors 2a and 2b, the diameter of the rotary blade (not shown) provided in the intake fan 3 is formed larger than the diameter of the outer conductor 2b. The rotation surface of the rotating blade is substantially perpendicular to the central axis direction of the concentric cylindrical electrode 2, and the rotation axis of the rotating blade and the central axis of the concentric cylindrical electrode 2 exist on the same straight line. An intake fan 3 is arranged and connected between the concentric cylindrical electrode 2 and the intake fan 3 so that there is no unevenness that disturbs the flow of airflow. The laminar flow is generated in the space between the two conductors 2a and 2b because the charged particles flowing into the space between the two conductors 2a and 2b from the inlet side (left side in FIG. 1) of the concentric cylindrical electrode 2 are generated. This is because the electric field is applied by moving the charged particles at a constant speed by advancing parallel to the axial direction of the concentric cylindrical electrode 2.

The ammeter 4 is a digital ammeter connected between the current measurement terminal 22 of the inner conductor 2a and the current measurement terminal 24 of the outer conductor 2b. The measured value of the current is measured by a current value acquisition unit 12 described later. Obtained automatically. The number of charged particles can be obtained from the current flowing between the inner conductor 2a and the outer conductor 2b. If the current flowing between the two conductors 2a and 2b is i _S , the charged number np of the charged particles is 1. Since it is assumed, the number n _{S of} charged particles is expressed by the following equation (3). When the charge number np is not 1, it can be calculated by multiplying the electric quantity e in the equation (3) by the charge number np.

n _S = i _S / (e × φ) (3)
Here, e is the elementary electric charge, and φ is the airflow rate.

  The voltage source 5 is a variable power source that applies a DC voltage to the outer conductor 2b via the voltage terminal 23, and the applied voltage is automatically controlled by a voltage control unit 11 described later so that measurement can be performed by automatic control. . The polarity of the voltage applied by the voltage source 5 can be switched between positive and negative. If the voltage applied by the voltage source 5 is positive, positive charged particles can be measured, and the applied voltage is negative. If so, negatively charged particles can be measured.

  The filter electrode 6 is arranged on the upstream side of the airflow flowing in the annular space 2c inside the concentric cylindrical electrode 2 in the outer space of the concentric cylindrical electrode 2, and charged particles having a particle size equal to or smaller than a predetermined threshold value in the annular space 2c. An electric field that does not flow is generated. The filter electrode 6 has the same configuration as the concentric cylindrical electrode 2 and has a cylindrical second inner conductor (hereinafter abbreviated as inner conductor) 6a and a second outer conductor (hereinafter abbreviated as outer conductor) having different radii. It is composed of concentric cylindrical electrodes with 6b concentrically arranged. The inner conductor 6a and the outer conductor 6b are preferably formed of a material having high conductivity so that charged particles having a desired particle diameter range can be attracted and easily removed as an electric current. For example, the inner conductor 6a and the outer conductor 6b are formed by applying chromium plating to the brass surface. Is done.

  The inner conductor 6 a includes a ground terminal 61, and is grounded via a ground wire 63 connected to the ground terminal 61. The inner conductor 6a is held in the outer conductor 6b via a holding member (not shown) having high insulating properties in order to prevent an error from occurring due to charging and current flowing. As a material for the member, it is preferable to use, for example, a highly insulating ethylene trifluoride chloride resin. The outer conductor 6 b includes a voltage terminal 62, and a DC voltage from the voltage source 7 is applied through the voltage terminal 62. Here, the ground terminal 61 of the inner conductor 6a and the voltage terminal 62 of the outer conductor 6b constitute a second voltage application terminal.

  The filter electrode 6 is connected to the concentric cylindrical electrode 2 via a double cylindrical insulating member 8. However, in order not to disturb the air flow by the insulating member 8, the filter electrode 6 is concentric cylindrical so as not to be uneven. The filter electrode 6 may be held in any form as long as it is held substantially parallel to the electrode 2. The holding member for holding the filter electrode 6 is preferably grounded in order to prevent an error from being generated due to charging and current flow.

  The voltage source 7 is a variable power source that applies a DC voltage to the outer conductor 6b via the voltage terminal 62, and the applied voltage is automatically controlled by a voltage control unit 11 described later so that measurement can be performed by automatic control. Note that the polarity of the voltage applied by the voltage source 7 can be switched between positive and negative so that charged particles having either positive or negative polarity can be removed.

  The insulating member 8 is a member that connects between the concentric cylindrical electrode 2 and the filter electrode 6, and is concentric cylindrical so that the airflow including the charged particles becomes a laminar flow without being disturbed when passing through the connecting portion. At the end of the electrode 2 on the entrance side, the inner conductors 2a and 6a and the outer conductors 2b and 6b are connected in parallel without unevenness. When the insulating member 8 is charged, charged particles are attracted and an error occurs due to the flow of current. Therefore, it is preferable to form the insulating member 8 with a material having high insulating performance. For example, the insulating member 8 is formed of a polyacetal resin which is a kind of engineering plastic. Yes.

  Next, the configuration of the controller 10 will be described. The controller 10 includes a voltage control unit 11, a current value acquisition unit 12, and an arithmetic processing unit 13 as main components.

  The voltage controller 11 automatically controls the applied voltage of the voltage source 5 based on the voltage value and polarity of the applied voltage input from the particle size calculator 15 described later. In addition, the voltage control unit 11 automatically controls the applied voltage of the voltage source 7 based on the voltage value and polarity of the applied voltage input from the removal voltage calculating unit 17 described later. Simultaneously with the setting, a function of outputting a particle size distribution acquisition signal for measuring the particle size distribution again to the particle size calculation unit 15 is also provided.

  The current value acquisition unit 12 automatically acquires a current measurement value from the ammeter 4 and outputs the acquired current value to the particle size calculation unit 15.

  The arithmetic processing unit 13 includes an input unit 14, a particle size calculation unit 15, a removal particle size calculation unit 16, and a removal voltage calculation unit 17. The voltage control unit 11 is used to set an applied voltage of the voltage sources 5 and 7. The particle size distribution of the charged particles is obtained based on the current value obtained from the current value acquisition unit 12. The arithmetic processing unit 13 is configured by using, for example, a microcomputer, and the particle size calculation unit 15, the removal particle size calculation unit 16, and the removal voltage calculation unit 17 are realized by a calculation function of the microcomputer.

  The input unit 14 is for the user to input measurement conditions such as the measurement range, polarity, and sweep width of the particle size of the charged particles to be measured. The input measurement conditions are output to the particle size calculation unit 15. Is done.

  The particle size calculation unit 15 calculates the voltage to be applied to the outer conductor 2b from the relationship between the particle size of the charged particle to be measured and the mobility in accordance with the measurement conditions input from the input unit 14, and calculates the calculation result as a voltage control unit. 11, and based on the current value acquired from the current value acquisition unit 12, the number of charged particles having a particle size equal to or smaller than the particle size set by the applied voltage of the voltage source 5 is calculated. In the particle size calculation unit 15, the voltage applied by the voltage source 5 is swept using the voltage control unit 11 to change the particle size of the measurement target by a predetermined sweep width, and the particle size of the measurement target is changed to the sweep width. By measuring the number of particles every time it is changed, the particle size distribution of the number of charged particles can be obtained. Further, the particle size calculator 15 outputs the polarity of the charged particles to be measured to the voltage controller 11 and outputs the polarity of the charged particles to be removed to the voltage controller 11. In addition, when the particle size calculation unit 15 acquires the particle size distribution acquisition signal from the voltage control unit 11, the particle size distribution is measured again within the measurement range of the particle size once set, and the measured particle size distribution is stored as electronic data. (Not shown) and the particle size distribution is output to an output device (printer, monitor device, etc.) not shown.

  Based on the particle size distribution of the charged particles obtained from the particle size calculation unit 15, the removal particle size calculation unit 16 removes the second largest particle size from among the particle sizes when the number of particles becomes maximum. Is obtained as the maximum particle size (threshold value) of the charged particles, and this particle size is output to the removal voltage calculation unit 17. The polarity of the charged particles to be measured input from the particle size calculator 15 is output to the removal voltage calculator 17 as the polarity of the charged particles to be removed.

  The removal voltage calculation unit 17 calculates the voltage to be applied to the outer conductor 6b of the filter electrode 6 based on the maximum particle size (threshold value) of the charged particles to be removed input from the removal particle size calculation unit 16, and applies the applied voltage. The calculated voltage value and polarity are output to the voltage control unit 11.

  Next, the operation of the charged particle amount evaluation apparatus 1 of the present embodiment will be described with reference to the flowchart of FIG.

  First, the power of the intake fan 3 is turned on, the rotating blades are rotated, and flow along the axial direction into the space between the inner conductors 2a, 6a and the outer conductors 2b, 6b of the concentric cylindrical electrode 2 and the filter electrode 6. A laminar flow with a flow rate of 50 L / min is generated.

  Next, the power sources of the voltage sources 5 and 7 and the controller 10 are turned on. However, when the power is turned on, the voltages of the voltage sources 5 and 7 are set to zero. The voltage sources 5 and 7 and the controller 10 may be turned on in conjunction with the power supply of the intake fan 3.

  When the controller 10 starts operation, the person in charge of measurement uses the input unit 14 to input measurement conditions such as the measurement range and polarity of the particle size of the charged particles and the sweep width of the particle size (step S1). In the following, the particle size measurement range is set to 0.6 to 28 nm, the polarity is set to negative, the sweep width is set to 0.2 nm for the particle size range of 0.6 to 2 nm, and 2 nm for the particle size range of 2 to 28 nm. The case will be described. If the direction of the current is taken into account in the ammeter, the input of the polarity of the voltage to be applied can be made unnecessary.

  Based on the measurement conditions input from the input unit 14, the particle size calculation unit 15 solves the above relational expressions (1) and (2) of the particle size, mobility, and applied voltage, thereby measuring objects. When the fluctuation range of the applied voltage corresponding to the particle size range and the sweep width of the applied voltage corresponding to the particle size sweep width are calculated, and the particle size is changed from the minimum value to the maximum value with a predetermined sweep width The applied voltage corresponding to each particle size is obtained (step S2).

  Next, the particle size calculator 15 outputs the voltage value and polarity of the applied voltage corresponding to the minimum value of the particle size to the voltage controller 11 (step S3). Under the current measurement conditions, the minimum value of the particle size is 0.6 nm.

  At this time, the voltage control unit 11 sets the applied voltage of the voltage source 5, and the applied voltage corresponding to the minimum value of the particle size is applied to the outer conductor 2b (step S4). The polarity of the voltage applied to the outer conductor 2b is the same as the polarity of the charged particles to be measured. When negatively charged particles are to be measured, the polarity of the voltage applied to the outer conductor 2b is negative. As a result, an electric field is generated from the inner conductor 2a to the outer conductor 2b, and negatively charged particles are attracted to the inner conductor 2a grounded to the ground by the electric field. Then, charged particles having a particle size equal to or smaller than the particle size set by the voltage applied by the voltage source 5 are taken into the inner conductor 2a, and a current flows between the inner conductor 2a and the outer conductor 2b (step S5). 1 indicates a path through which charged particles removed by the filter electrode 6 flow, and an arrow b indicates a path through which charged particles flowing into the concentric cylindrical electrode 2 flow.

  When a current flows due to the charged particles taken into the inner conductor 2a, the current value is measured by the ammeter 4, and the measured value is automatically acquired by the current value acquisition unit 12 (step S6).

  The current value acquisition unit 12 outputs the acquired current value to the particle size calculation unit 15, and the particle size calculation unit 15 calculates the number of charged particles having a particle size equal to or smaller than the minimum particle size using the above-described equation (3). The particle size and the number of target charged particles are stored in a storage unit (not shown) (step S7).

  When the particle size and number of charged particles to be measured are stored, the particle size calculation unit 15 determines whether or not the measurement has been completed for all measurement ranges (step S8). After the voltage value and polarity of the applied voltage when the diameter is increased by a predetermined sweep width are output to the voltage control unit 11 (step S9), the processes of steps S4 to S7 described above are repeated. Since the sweep width is 0.2 nm in the particle diameter range of 0.6 to 2 nm, the voltage value of the applied voltage when the particle diameter is 0.8 nm is output next to the minimum particle diameter.

  Each time the particle size is swept from 0.6 nm to 28 nm by a predetermined sweep width as described above, the number of particles is calculated by repeating the above steps S4 to S7 with each particle size setting value. When the diameter distribution (number distribution with respect to the particle diameter) is obtained and it is determined in step S8 that the measurement has been completed in the entire measurement range, the particle diameter calculation unit 15 calculates the particle diameter distribution calculation result to calculate the removal particle diameter. It outputs to the part 16 (step S10).

  The removal particle size calculation unit 16 searches for a particle size peak based on the particle size distribution input from the particle size calculation unit 15. Here, in the example of the particle size distribution shown in FIG. 3A, the number of particles is maximized when the particle size is 1.4 nm and 14 nm, and the second of the particle sizes when the number of particles is maximized. Is set to the maximum diameter (threshold value) of the charged particles to be removed, and is output to the removal voltage calculation unit 17 (step S11).

  Here, the removal voltage calculation unit 17 can calculate the applied voltage corresponding to the particle size (threshold value) of the charged particles to be removed by simultaneously solving the above formulas (1) and (2). The calculation result is output to the voltage controller 11 as a set value of the applied voltage (step S12).

  The voltage control unit 11 sets the applied voltage of the voltage source 7 based on the set value and polarity of the applied voltage input from the removal voltage calculating unit 17 and simultaneously outputs a particle size distribution acquisition signal to the particle size calculating unit 15. (Step S13). At this time, a DC voltage of a predetermined voltage is applied from the voltage source 7 to the outer conductor 6 b of the filter electrode 6. The polarity of the voltage applied to the outer conductor 6b is the same as the polarity of the charged particles to be measured. When negatively charged particles are to be removed, the polarity of the voltage applied to the outer conductor 6b is set to be negative. As a result, an electric field is generated from the inner conductor 6a to the outer conductor 6b, and negatively charged particles are attracted to the inner conductor 6a grounded to the ground by this electric field. Then, the charged particles whose particle size is equal to or smaller than the threshold set by the voltage applied by the voltage source 7 are taken into the inner conductor 6a and removed as an electric current. Therefore, the charged particles whose particle size is equal to or smaller than the threshold are removed by the filter electrode 6. Will be.

  When the particle size distribution acquisition signal is output from the voltage control unit 11 to the particle size calculation unit 15 with the charged particles having a small particle size removed by the filter electrode 6 in this manner, the particle size calculation unit 15 The particle size distribution is measured again by executing the processes of steps S3 to S10, and a particle size distribution excluding charged particles having a particle size equal to or smaller than a threshold value can be obtained. The measurement result of the excluded particle size distribution is stored in the storage unit, and the measurement result is output to the output device (step S14). FIG. 3B shows the measurement result of the particle size distribution when a predetermined voltage is applied to the filter electrode 6 to remove charged particles having a particle size of 1.4 nm or less. You can see that it is gone.

  As described above, in the charged particle amount evaluation apparatus 1 according to the present embodiment, the filter electrode 6 is disposed on the upstream side of the air flow in the external space of the concentric cylindrical electrode 2, and the voltage value corresponding to the particle size to be removed. By applying a voltage having a polarity and being applied to the outer conductor 6b, charged particles having a predetermined particle size or less can be attracted to the inner conductor 6a and taken into the inner conductor 6a to be removed as a current. Therefore, since there are charged particles with a small particle size such as negative ions having a particle size of about 1 nm, even when the particle size distribution of the charged particles contained in the air has a plurality of particle size peaks, Since charged particles having a predetermined particle size or less can be removed by the filter electrode 6 due to the difference in electric mobility, the S / N ratio when measuring charged particles having a large particle size can be improved. It becomes possible to improve reproducibility and reliability.

  In this embodiment, the voltage applied to the outer conductor 2b of the concentric cylindrical electrode 2 is swept in a state where no voltage is applied to the outer conductor 6b of the filter electrode 6, and the particle size distribution of the number of particles is obtained. The maximum particle size (particle size threshold) of the charged particles to be removed by searching for the maximum point (particle size peak) appearing in the diameter distribution and determining the particle size corresponding to the unnecessary maximum point (particle size peak) However, if the particle size of the charged particles to be removed is obtained in advance, the person in charge of measurement directly inputs the applied voltage of the voltage source 7 corresponding to the particle size to be removed using the input unit 14. You may do it.

  Further, since the filter electrode 6 is constituted by a concentric cylindrical electrode of the inner conductor 6a and the outer conductor 6b, the charged particles to be removed are attracted to the inner conductor 6a or the outer conductor 6b and removed as an electric current. By removing charged particles other than the target without leaving them in the space, the measurement accuracy can be improved, and the spatial distribution of the charged particles can be accurately detected.

  In addition, the radius of the inner conductor 6a and the outer conductor 6b of the filter electrode 6 is set to be substantially the same as the radius of the inner conductor 2a and the outer conductor 2b of the concentric cylindrical electrode 2, so that the concentric cylindrical electrode 2 There is no unevenness in the connecting portion with the filter electrode 6, and the concentric cylindrical electrode 2 and the filter electrode 6 are interposed via the insulating member 8 in a state where the inner conductors 2 a and 6 a and the outer conductors 2 b and 6 b are overlapped. Therefore, discontinuous points do not occur in the connected portion. Therefore, since the airflow is not disturbed when the gas flows into the concentric cylindrical electrode 2 through the filter electrode 6, the charged particle size distribution can be accurately determined while removing the charged particles having a small particle size. Can be measured.

  Since the size of the filter electrode 6 is determined by the particle diameter of the charged particles to be removed, the radius of the inner conductor 6a and the outer conductor 6b of the filter electrode 6 is set so that the inner conductor 2a and the outer conductor 2b of the concentric cylindrical electrode 2 In some cases, the value may be set to a value different from the radius. However, even in such a case, the charged particles to be removed can be removed without leaving in the space by using concentric cylindrical electrodes. For example, as shown in FIG. 4, the radius of the inner conductor 6a of the filter electrode 6 may be smaller than the radius of the inner conductor 2a of the concentric cylindrical electrode 2, but the radius of the outer conductor 6b of the filter electrode 6 is concentric. The generation of turbulence can be reduced by forming the filter electrode 6 in a shape substantially the same as that of the concentric cylindrical electrode 2 so that the radius is substantially the same as the radius of the outer conductor 2 b of the cylindrical electrode 2.

  In this embodiment, when the particle size range, polarity, and sweep width of the charged particles to be measured are set using the input unit 14, the controller 10 automatically changes the applied voltage of the voltage source 5 to determine the number of charged particles. When the particle size distribution is measured, and there are multiple particle sizes that have the maximum number of particles, the second largest particle size is set to the maximum particle size (threshold value) of the charged particles to be removed. Since the particles are removed, even when the particle size range of the charged particles to be removed is unknown, the maximum particle size of the charged particles to be removed can be automatically set, so the voltage applied to the filter electrode 6 It is possible to save the trouble of setting the measurement person by himself. Here, FIG. 3 (a) shows an example with only two maximum values, but when there are five maximum values of the number of particles, it corresponds to the fourth maximum value from the smallest particle size. If it is desired to measure the number of particles having a particle size, the applied voltage of the voltage source 5 is small so that the particle size corresponding to the fourth maximum value from the smallest is the maximum value in the particle size measurement range. Since the particle size corresponding to the third maximum value from the side is set as the threshold value, any maximum value can be set as the threshold value by setting the voltage applied by the voltage source 5, and the number of particles having a desired particle size can be measured. Is possible.

  In this embodiment, an ammeter (not shown) for measuring the current flowing between the inner conductor 6a and the outer conductor 6b of the filter electrode 6 may be provided, and the particle size measured by the concentric cylindrical electrode 2 may be provided. Charged particles having a particle size different from that of the charged particles can be measured simultaneously.

  In this embodiment, the concentric cylindrical electrode 2 and the inner conductors 2a and 6a of the filter electrode 6 are grounded, and the DC voltage of the voltage sources 5 and 7 is applied to the outer conductors 2b and 6b. Even when a voltage is applied to the second inner conductor 2a and the outer conductor 2b is grounded, charged particles can be measured in the same manner as described above. Further, even when a voltage is applied to the inner conductor 6a of the filter electrode 6 and the outer conductor 6b is grounded, charged particles having a predetermined particle diameter or less can be removed as described above.

  Further, the inner conductor 2a of the concentric cylindrical electrode 2 is provided with a current measuring terminal 24, the outer conductor 2b is provided with a voltage terminal 23 and a current measuring terminal 24, and the outer conductor 6b of the filter electrode 6 is provided with a voltage terminal 62. , The ammeter 4 and the voltage sources 5 and 7 do not have to be integrated into the charged particle amount evaluation apparatus 1 itself, and the ammeter 4 and the voltage sources 5 and 6 having different configurations are connected to the concentric cylindrical electrode 2 and It is possible to perform measurement by connecting to the terminal of the filter electrode 6.

(Embodiment 2)
Embodiment 2 of the charged particle amount evaluation apparatus using the charged particle amount evaluation method according to the present invention will be described with reference to FIG. In the first embodiment described above, the filter electrode 6 having the same shape as the concentric cylindrical electrode 2 is used, but in this embodiment, a flat plate-like filter electrode 6 ′ is used. Since the configuration other than the filter electrode 6 'is the same as that of the first embodiment, the same components are denoted by the same reference numerals and the description thereof is omitted.

  The filter electrode 6 ′ has a flat plate shape and is disposed in the outer space of the concentric cylindrical electrode 2 on the upstream side of the airflow flowing through the concentric cylindrical electrode 2. A voltage having the same polarity as the charged particles to be removed is applied to the filter electrode 6 ′ by the voltage source 7, and a repulsive force is applied to the charged particles to be removed to generate an electric field that does not flow into the concentric cylindrical electrode 2. The charged particles having a predetermined particle diameter or less are blown off by receiving a repulsive force due to the electric field, and only charged particles larger than the predetermined particle diameter can flow into the concentric cylindrical electrode 2. In the figure, an arrow a indicates a path through which charged particles having a predetermined particle diameter or less flow, and an arrow b indicates a path through which charged particles larger than the predetermined particle diameter flow. Here, the filter electrode 6 ′ is preferably formed of a good conductor that is easily charged so that a repulsive force can be applied to the charged particles having a particle diameter to be removed, and the support member of the filter electrode 6 ′ is charged. Since there is a possibility, it is preferable to form the support member with an insulator in order to prevent accidents such as electric shock.

  The operation of the charged particle amount evaluation apparatus 1 of this embodiment will be described below. First, the power of the intake fan 3 is turned on, the rotating blades are rotated, and a laminar flow with a flow rate of 50 L / min flowing along the axial direction in the space between the inner conductor 2a and the outer conductor 2b of the concentric cylindrical electrode 2 is obtained. Is generated.

  Next, the power sources of the voltage sources 5 and 7 and the controller 10 are turned on. However, when the power is turned on, the voltages of the voltage sources 5 and 7 are set to zero. The voltage sources 5 and 7 and the controller 10 may be turned on in conjunction with the power supply of the intake fan 3.

  When the controller 10 starts operating, the person in charge of measurement uses the input unit 14 to input measurement conditions such as the particle size range and polarity of the charged particles to be measured and the sweep width of the particle size. Based on the measurement conditions input from the input unit 14, the particle size calculation unit 15 solves the above relational expressions (1) and (2) of the particle size, mobility, and applied voltage, thereby measuring objects. When the fluctuation range of the applied voltage corresponding to the particle size range and the sweep width of the applied voltage corresponding to the particle size sweep width are calculated, and the particle size is changed from the minimum value to the maximum value with a predetermined sweep width The applied voltage corresponding to each particle size is obtained.

  Then, the particle size calculator 15 outputs the voltage value and polarity of the applied voltage to the voltage controller 11, and the voltage controller 11 sets the applied voltage of the voltage source 5 and sweeps the applied voltage within a predetermined voltage range. Each time the particle size calculation unit 15 calculates the number of particles based on the current value acquired by the current value acquisition unit 12, the particle size distribution of the number of particles is obtained, and the calculation result of the particle size distribution is removed. Output to the particle size calculator 16.

  The removal particle size calculation unit 16 searches for the particle size when the number of particles becomes maximum based on the particle size distribution input from the particle size calculation unit 15, and among the particle sizes when the number of particles becomes maximum, The second largest particle size is set as the maximum particle size (threshold value) of the charged particles to be removed and output to the removal voltage calculation unit 17.

  The removal voltage calculation unit 17 calculates the applied voltage corresponding to the particle size of the charged particles desired to be removed by simultaneously solving the above equations (1) and (2) and outputs the calculated voltage to the voltage control unit 11.

  The voltage control unit 11 sets the applied voltage of the voltage source 7 based on the set value and polarity of the applied voltage input from the removal voltage calculating unit 17 and simultaneously outputs a particle size distribution acquisition signal to the particle size calculating unit 15. . At this time, a predetermined DC voltage is applied to the filter electrode 6 ′ by the voltage source 7. The polarity of the voltage applied to the filter electrode 6 ′ is the same as the polarity of the charged particles to be measured. This applies a repulsive force to the charged particles to be removed, and blows them outside the concentric cylindrical electrode 2.

  When the particle size distribution acquisition signal is output from the voltage control unit 11 to the particle size calculation unit 15 in a state where charged particles having a small particle size are removed by the filter electrode 6 ′ in this way, the particle size calculation unit 15 The particle size distribution is measured again by performing the same process as above, and a particle size distribution excluding charged particles having a particle size equal to or smaller than a threshold value can be obtained.

  As described above, in this embodiment, the filter electrode 6 ′ having a simple shape (flat plate shape) is disposed in the outer space of the concentric cylindrical electrode 2 and upstream of the airflow flowing inside the concentric cylindrical electrode 2. In addition, by applying a voltage having the same polarity as that of the charged particles to be removed to the filter electrode 6 ′, a repulsive force is applied to the charged particles to be removed and blown off to the outside of the concentric cylindrical electrode 2. Charged particles having a particle size or less can be removed. Therefore, since there are charged particles with a small particle size such as negative ions having a particle size of about 1 nm, even when the particle size distribution of the charged particles contained in the air has a plurality of particle size peaks, Since charged particles having a predetermined particle size or less can be removed by the filter electrode 6 ′ due to the difference in electric mobility, the S / N ratio when measuring charged particles having a large particle size can be improved. It becomes possible to improve reproducibility and reliability.

  In the present embodiment, the filter electrode 6 ′ is formed in a flat plate shape, but the shape and size of the filter electrode 6 ′ may be any shape and size as long as the airflow flowing into the concentric cylindrical electrode 2 is not disturbed. You may form in. For example, the filter electrode 6 ′ may be formed in a semi-cylindrical shape having the same radius as the outer conductor 2 b of the concentric cylindrical electrode 2, and charged from the charged particle source inside the concentric cylindrical electrode 2 without disturbing the flow of airflow. An air stream containing particles can be introduced.

In this embodiment, an applied voltage having the same polarity as that of the charged particles to be removed is applied to the filter electrode 6 '. However, an applied voltage having a polarity opposite to that of the charged particles to be removed is applied to the filter electrode 6'. The charged particles to be removed can be attracted to the filter electrode 6 ′ side and taken into the filter electrode 6 ′ to be removed as a current (Embodiment 3).
Embodiment 3 of the charged particle amount evaluation apparatus using the charged particle amount evaluation method according to the present invention will be described with reference to FIG. In the first embodiment, the filter electrode 6 having the same shape as that of the concentric cylindrical electrode 2 is used. However, in this embodiment, the filter electrode 6 is substantially tubular, and the cross-sectional area becomes smaller as the side is closer to the concentric cylindrical electrode 2. The filter electrode 6 ″ formed in such a tapered shape is used. Since the configuration other than the filter electrode 6 ″ is the same as that of the second embodiment, common constituent elements are denoted by the same reference numerals. The description is omitted.

  The filter electrode 6 ″ includes a tapered portion 65 formed in a tapered shape such that the cross-sectional area becomes smaller toward the side closer to the concentric cylindrical electrode 2, and a straight pipe extended from the end portion on the small diameter side of the tapered portion 65. And is disposed outside the concentric cylindrical electrode 2 on the upstream side of the airflow flowing through the concentric cylindrical electrode 2.

  A voltage having the same polarity as that of the charged particles to be removed is applied to the filter electrode 6 ″ by the voltage source 7, and an electric field is applied so that the charged particles having a particle diameter to be removed do not flow into the straight pipe portion 64 by applying repulsive force to the charged particles. The charged particles having a predetermined particle size or less are blown off by receiving a repulsive force due to the electric field, and only charged particles larger than the predetermined particle size can flow into the straight pipe portion 64 through the taper portion 65. In the figure, an arrow a indicates a path through which charged particles having a predetermined particle diameter or less flow, and an arrow b indicates a path through which charged particles larger than the predetermined particle diameter flow. Here, the filter electrode 6 ″ is to be removed. It is preferable to form a good conductor that is easily charged so that repulsive force can be applied to the charged particles having a particle size, and the support member of the filter electrode 6 ″ may be charged. Preferably formed of an insulating material in order to prevent accidents.

  Since the operation of this embodiment is the same as that of the charged particle amount evaluation apparatus 1 described in the second embodiment, the description thereof is omitted.

  In the present embodiment, a tapered electrode 65 is provided on the filter electrode 6 ″, thereby forming a tapered tubular electrode having a smaller cross-sectional area toward the side closer to the concentric cylindrical electrode 2. The passage of the airflow excluding the charged particles with a threshold value of less than the threshold value is secured, and the influence on the spatial distribution of the charged particles can be reduced, and the radius of the straight pipe portion 64 is the radius of the outer conductor 2b of the concentric cylindrical electrode 2. The connecting portion between the straight pipe portion 64 and the outer conductor 2b is preferably connected via an insulating member or the like so as not to be uneven. If the straight pipe portion 64 and the outer conductor 2b cannot be connected, the radius of the straight pipe portion 64 is substantially the same as the radius of the outer conductor 2b of the concentric cylindrical electrode 2, or Slightly larger than that By forming the dimensions of order may be suppressed airflow being disturbed at the boundary of the filter electrodes 6 'and the concentric cylindrical electrodes 2.

  It should be noted that a wide variety of different embodiments can be configured without departing from the spirit and scope of the present invention, and the present invention is not limited to a specific embodiment.

1 is a schematic configuration diagram of a charged particle amount evaluation apparatus according to Embodiment 1. FIG. It is a flowchart explaining operation | movement same as the above. (A) and (b) are particle size distribution diagrams measured using the same as above. It is a schematic block diagram of the other structure same as the above. 6 is a schematic configuration diagram of a charged particle amount evaluation apparatus according to Embodiment 2. FIG. It is a schematic block diagram of the charged particle amount evaluation apparatus of Embodiment 3. It is a schematic block diagram of the conventional charged particle amount evaluation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charged particle amount evaluation apparatus 2 Concentric cylindrical electrode 2a, 6a Inner conductor 2b, 6b Outer conductor
2c Annular space 3 Intake fan 4 Ammeter 5 Voltage source 6 Filter electrode 7 Voltage source 10 Controller

Claims (4)

A first concentric cylindrical electrode configured by concentrically arranging a cylindrical first inner conductor and a first outer conductor having different radii, and an annular space between the first inner conductor and the first outer conductor. An airflow generating means for generating an airflow along the axial direction, a first voltage application terminal for applying a DC voltage between the first inner conductor and the first outer conductor, and a first inner conductor; A current measuring terminal provided on each of the first outer conductors and for measuring a current flowing between the two conductors; and an external space of the first concentric cylindrical electrode, disposed upstream of the airflow, A filter electrode provided with a second voltage application terminal to which a voltage is applied to generate an electric field that prevents charged particles having a particle size of a predetermined threshold value or less from flowing into the annular space by the electrode ;
Voltage control means for adjusting the applied voltages by the first and second voltage sources, respectively, for applying a DC voltage to the first and second voltage application terminals, respectively, and measurement of the current measurement means connected to the current measurement terminal A current value acquisition unit for acquiring a value, and a particle when the current value acquired by the current value acquisition unit becomes a maximum when the voltage control unit sweeps the voltage applied by the first voltage source in a predetermined voltage range. A removed particle size acquisition unit that acquires the second largest particle size of the diameters as the threshold value, and charged particles having a particle size equal to or less than the threshold value in the annular space based on the threshold value acquired by the removal particle size acquisition unit. A removal voltage calculation means for calculating a voltage value for generating an electric field that does not flow in, and the voltage control means controls the voltage applied by the second voltage source to the voltage value calculated by the removal voltage calculation means. Features Charged particle amount evaluation device.   2. The charging according to claim 1, wherein the filter electrode includes a second concentric cylindrical electrode configured by concentrically arranging a cylindrical second inner conductor and a second outer conductor having different radii. Particle amount evaluation device.   The first inner conductor and the second inner conductor, and the first outer conductor and the second outer conductor have substantially the same radius, and the first and second concentric cylindrical electrodes are respectively 3. The charged particle amount according to claim 2, wherein the inner conductor and the outer conductor are connected to each other through an insulating member at an upstream end of the first concentric cylindrical electrode. Evaluation device. A DC voltage is applied between both conductors of a concentric cylindrical electrode formed by concentrically arranging a cylindrical first inner conductor and a first outer conductor having different radii, and an axial direction is formed in an annular space between the two conductors. A charged particle amount evaluation method for generating an airflow flowing along the airflow, causing charged particles to flow through the annular space between the two conductors by the airflow, and evaluating the amount of charged particles from the current value of the current flowing between the two conductors,
  The particle size distribution of the number of charged particles flowing between the two conductors is measured, and the second largest particle size is obtained as the threshold value of the particle size to be removed, and the concentric cylindrical shape is obtained. An applied voltage set based on the threshold value is applied to a filter electrode arranged on the upstream side of the air flow, which is an external space of the electrode, and charged particles having a particle size equal to or smaller than the threshold value are annular spaces between the two conductors. A charged particle amount evaluation method comprising measuring again the particle size distribution of the number of charged particles flowing between the two conductors in a state where an electric field that does not flow into the conductor is generated.

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