JP2007127457A - Ion measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion measuring instrument that is less likely to produce measuring errors caused by the re-bonding of ions. <P>SOLUTION: A center electrode 1 is provided in an electrode body 10 and formed into a rotor shape, having a leading end part reduced in diameter, as going toward its leading end. A cylindrical electrode 3 is provided outside of the center electrode 1 and formed into a cylindrical shape so as to surround the center electrode 1 to allow gaseous ions to flow through the gap formed, with respect to the outer surface of the center electrode 1 as a laminar flow. A positive voltage is applied to the center electrode 1, and a negative voltage is applied to the cylindrical electrode 3. When the gaseous ions are introduced into the electrode body 10 from a gaseous ion inlet port 7, they flow through the gap between both electrodes 1 and 3 as the laminar flow, and respective ions are detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ion measuring instrument for measuring a gas ion generation amount associated with a radiation source or discharge. For example, the present invention relates to an ion measuring device for accurately measuring or inspecting the amount of gas ions generated from an ion generator used when charging particles.

For charged particles and ions (or ion clusters) applied to analysis, medicine, semiconductor fields, etc., it is important to maintain the accuracy to measure the total amount used. Therefore, an ion measuring device that measures the amount of ions generated is used. Charged particles and ions have the same electrical properties, but ions have an electric mobility of about 1 cm ² / Vs, and charged particles have a particle size larger than that of ions but smaller electric mobility. Shall mean.

  The particles become charged particles by, for example, diffusion charging by gas ions. This is because a part of the neutral gas such as the atmosphere is ionized by americium or corona discharge, and the gas ions collide with the particle by diffusion, and the particle is charged by attaching to the particle or exchanging its charge. It is to be done.

  FIG. 2 is a vertical sectional view of a conventional ion measuring instrument. In this ion measuring instrument, parallel plate electrodes 2a and 2b are opposed to the inside of an electromagnetic shield 5 having a gas ion introduction port 7 for gas ions (a gas containing ions) at the upper portion and a gas ion discharge port 9 at the lower portion. It is prepared. In this apparatus, all the ions are taken into the vessel and the charge amount of the ions is measured.

When a DC voltage on the order of several kV to several tens of kV is applied to the parallel plate electrodes 2a and 2b by the power source 11, and gas ions generated by the ion generator 15 are allowed to flow between the electrodes 2a and 2b, the electrodes 2a and 2b Positive and negative ions are respectively detected by 2b, and the amount of ions generated in the ion generator 15 is measured from the current value by the current measuring unit 13 (see Patent Document 1).
Japanese Patent Laid-Open No. 2003-14694

  In the conventional ion measuring device, the total charge amount of ions is measured by the parallel plate electrodes 2a and 2b provided in the shield 5, but the shield 5 and the electrode are applied by applying an electric field between the parallel plate electrodes 2a and 2b. Some of the ions are captured by the shield 5 due to the electric field generated between 2a and 2b, which may cause an error.

Furthermore, since both electrodes 2a and 2b of the conventional ion measuring device have a shape in which the flat plates face each other, even if an attempt is made to separate positive and negative ions by an electric field, if there is a very intense turbulent flow, the gas is mixed and the positive and negative ions are mixed. May recombine, which may cause measurement errors.
In addition, if the ion current stays in a place where the electric field is weak or turbulent, deposition on the wall accompanied by the flow of current occurs due to recombination or diffusion of ions, which may cause measurement errors. there were.

  An object of the present invention is to provide an ion measuring instrument in which measurement errors due to such a decrease in ions are unlikely to occur, and to accurately measure the amount of gas ions generated for charging particles.

  The ion measuring instrument of the present invention is arranged on a central axis and has a rotating body-shaped center electrode having a tip portion whose diameter becomes narrower toward the tip, a cylindrical electrode placed outside the center electrode, and a cylindrical shape An electrode body having an electromagnetic shield surrounding the outside of the electrode, having a gas ion introduction port for introducing gas ions from the outside toward the tip portion on the central axis, and having a gas discharge port on the opposite side of the tip portion; A power source that separates the gas ions into positive or negative ions by applying a DC electric field for ion detection between the two electrodes, and a current measuring unit that measures a current value of the separated ions are provided. The cylindrical electrode is formed up to the vicinity of the inlet of the gas ion inlet, and an ion that forms a sheath gas flow surrounding the gas ion introduced from the gas ion inlet around the gas ion inlet. Alternatively, a plurality of sheath gas inlets for introducing a gas not containing charged particles are equally arranged and opened.

  You may make it further provide the exhaust mechanism for attracting | sucking the gas in the said electrode body main body downstream from the said gas exhaust port.

  An example of the center electrode is columnar except for the tip, and the distance between the columnar portion and the cylindrical electrode is preferably constant.

  In order to facilitate the laminar flow of the gas, a guide for making the gas flow along the gap between the electrodes may be provided at a part between the electrodes.

  A rotating body-shaped center electrode having a tip portion whose diameter becomes narrower toward the tip, and a cylindrical electrode disposed outside the center electrode, the cylindrical electrode is formed up to the vicinity of the entrance of the gas ion inlet, Since a plurality of sheath gas inlets for introducing a gas that does not contain ions or ions that form a sheath gas flow surrounding the gas ions around the gas ion inlets are evenly arranged, gas ions are layered between both electrodes. Since it is easy to flow as a flow and ions are not detected by the electrodes and are not captured by the shield, and recombination of ions is less likely to occur, the charge amount of ions can be accurately measured.

  If an exhaust mechanism for sucking the gas in the electrode body is further provided, a relatively large amount of gas can be sucked, so that gas ions can be introduced into the electrode body in a short time and the measurement is shortened. Can be done in time.

  If the center electrode is formed in a cylindrical shape excluding the tip, and the distance between the electrodes is constant in the cylindrical portion, the introduced gas can easily flow as a laminar flow, and the amount of charge of ions The measurement accuracy can be increased.

  By providing a guide for making the gas flow along the gap between the electrodes, it becomes easier to make the gas flow exhausted by the exhaust mechanism into a laminar flow.

Hereinafter, the present invention will be specifically described with reference to an example.
1A and 1B are schematic views of an ion measuring instrument according to an embodiment, where FIG. 1A is a vertical sectional view and FIG. 1B is a top view. Reference numeral 10 denotes an electrode body, in which a center electrode 1 is provided. The center electrode 1 has a tip portion with a diameter narrowing toward the tip, and is formed in a rotating body shape having a cylindrical shape below the tip portion. The center axis of the center electrode 1 and the center of the electrode body 10 Arranged so that the axes coincide. The gas ion introduction side is called the tip, and here the upper side is the tip side.

A cylindrical electrode 3 is provided outside the center electrode 1, and the cylindrical electrode 3 is cylindrical so as to surround the center electrode 1 so that gas ions flow as a laminar flow between the outer surface of the center electrode 1. Is formed. The central axis of the cylindrical electrode 3 also coincides with the central axis of the electrode body 10.
The diameter of the disk-shaped part of the central electrode 1 is 30 mm, the inner diameter of the cylindrical electrode 3 is 50 mm, and the distance L between the central electrode 1 and the cylindrical electrode 3 is about 10 mm in the cylindrical part of the central electrode 1. It is constant.

On the outside of the cylindrical electrode 3, an electromagnetic shield 5 made of a metal plate or a metal mesh is provided via an insulating material 4 to block electromagnetic noise from entering the outside of the electrode body 10. As the insulating material 4, for example, vinyl chloride or other resins can be used.
A gas ion introduction port 7 for guiding gas ions to the inside of the electrode body 10 is provided on the central axis at the front end portions of the electromagnetic shield 5 and the insulating material 4, and at the rear end portions of the electromagnetic shield 5 and the insulating material 4. Is provided with a discharge port 9 on the central axis for discharging the measured gas from the electrode body 10 to the outside.

  In order to facilitate the flow of the gas introduced from the gas ion introduction port 7 as a laminar flow within the electrode body 10, the tip of the center electrode 1 and the gas ion introduction port 7 are spaced by 20 mm. Further, the length of the center electrode 1 is 200 mm, and the length of the hole of the gas ion introduction port 7 is 2 mm. These numerical values are for explaining an example of the size of the ion measuring instrument, and are not limited thereto.

A pump 20 is provided downstream of the discharge port 9 as an exhaust mechanism for exhausting the gas ions introduced from the gas ion introduction port 7, and the gas inside the electrode body 10 is exhausted at a flow rate of 10 L / min. To do.
In order to introduce a gas that does not contain ions or charged particles that form a sheath gas flow surrounding the gas ions introduced from the gas ion introduction port 7 into the electromagnetic shield 5 and the insulating material 4 at the upper end of the electrode body 10. A number of sheath gas inlets 17 are equally arranged and opened. The diameter of the gas ion inlet 7 is 10 mm, and the diameter of the sheath gas inlet 17 is 2 mm. The diameter of the sheath gas inlet 17 is not limited to 2 mm. Further, instead of the sheath gas introduction port 17, for example, a filter having a hole parallel to the gas ion introduction port 7 may be disposed around the gas ion introduction port 7.

When exhausted from the electrode body 10 to the outside by the pump 20 at a flow rate of 10 L / min, gas ions and gas ions are introduced at a flow rate of 1 L / min from the gas ion inlet 7 and 9 L / min from the sheath gas inlet, respectively. A gas free of ions or charged particles is introduced.
As the gas not containing ions or charged particles, for example, air can be used.

  In order to make the flow of gas ions and sheath gas flow along the gap between the electrodes 1, 3, a guide 18 is provided so as to surround a cylindrical position below the center electrode 1. As the guide 18, a non-conductive material such as resin can be used as long as it has a large number of gaps parallel to the central axis.

  Reference numeral 11 denotes a DC power supply device, which is connected to both electrodes 1 and 3 in order to apply a DC voltage of about 0 to +10 kV or 0 to −10 kV between the electrodes 1 and 3. The electrodes 1 and 3 are connected to a current measuring unit 13 for measuring gas ions attracted by a DC electric field.

An ion generator 15 that can generate positive and negative gas ions at substantially the same concentration by corona discharge at a high frequency and high voltage is provided upstream of the gas ion introduction port 7. The main purpose of the ion measuring instrument of the present invention is to examine the performance of gas ion generation by the ion generator 15.
Examples of the ion generator 15 include a high-voltage power source and a discharge ion generator, and those having an α-ray source americium of a radioactive substance as an ion generation source.

Next, the operation of the embodiment will be described.
A positive voltage is applied to the center electrode 1 and a negative voltage is applied to the cylindrical electrode 3 by the power source 11, and the electromagnetic shield 5 is grounded. In this case, the amount of ions between the cylindrical electrode 3 and the ground, that is, the amount of positive ions is measured.
The gas to be measured is a gas ion used when charging the particles, and one generated by the gas ion generator 15 is used. By sucking the gas inside the electrode body from the discharge port 9 by the pump 20, gas ions are introduced from the gas ion introduction port 7, air is introduced from the sheath gas introduction port 17, and the gas ions are layered along the guide 18. A current flows between the electrodes 1 and 3.

  Since the gas ions are positively or negatively charged, they flow in a laminar flow without causing violent turbulence, and ion recombination hardly occurs. Therefore, ions are selectively captured by the center electrode 1 or the cylindrical electrode 3, the current value flowing between the electrodes 1 and 3 is measured by the current measuring unit 13, and the total charge amount of the particles is obtained with high accuracy.

  In the above embodiment, the case of measuring the amount of positive ions has been described. However, in the case of measuring the amount of negative ions, the direction of the voltage by the power source 11 is reversed or the positions of the power source 11 and the current measuring unit 13 are measured. Should be reversed.

  INDUSTRIAL APPLICABILITY The present invention can be used for an ion measuring device that measures a gas ion generation amount accompanying a radiation source or discharge.

The schematic of the ion measuring device of one Example is shown, (A) is a vertical sectional view, (B) is a top view. It is the schematic which shows the conventional ion measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Center electrode 3 Cylindrical electrode 4 Insulation material 5 Electromagnetic shield 7 Gas ion introduction port 9 Discharge port 10 Electrode body 11 Power supply 13 Current measurement part 15 Ion generator 17 Sheath gas introduction port 18 Guide 20 Pump

Claims (4)

A rotating body-shaped center electrode disposed on the central axis and having a tip portion with a diameter narrowing toward the tip, a cylindrical electrode disposed outside the center electrode, and an electromagnetic surrounding the outside of the cylindrical electrode An electrode body having a shield, having a gas ion introduction port for introducing gas ions from the outside toward the tip portion on the central axis, and having a gas discharge port on the opposite side of the tip portion;
A power source for separating the gas ions into positive or negative ions by applying a DC electric field for ion detection between the electrodes;
A current measuring unit for measuring a current value due to the separated ions,
The cylindrical electrode is formed to the vicinity of the inlet of the gas ion inlet,
Around the gas ion introduction port, a plurality of sheath gas introduction ports for introducing a gas that does not contain ions or charged particles forming a sheath gas flow surrounding the gas ion introduced from the gas ion introduction port are evenly arranged. An ion measuring instrument that has been opened.   The ion measuring device according to claim 1, further comprising an exhaust mechanism for sucking a gas in the electrode body main body downstream of the gas exhaust port.   3. The ion measuring instrument according to claim 1, wherein the center electrode has a columnar shape excluding a tip portion, and a distance between the columnar portion and the cylindrical electrode is constant.   The ion measuring instrument according to any one of claims 1 to 3, wherein a guide for making a gas flow along a gap between the two electrodes is provided at a part between the two electrodes.

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