JP2010096678A - Device and method of ionization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a method of ionization achieving efficient, stable and safe ionization. <P>SOLUTION: The ionization device includes an X-ray tube 1 and a metal thin film 2a disposed in a contact state with a gas flowing in a gas passage, and is configured so that X-ray beams 5 from the X-ray tube 1 irradiate the metal thin film 2a and thus photoelectrons are emitted in the gas passage. Because the ionization device adopts a configuration in which electrons generated when X-ray beams irradiate the metal thin film of a metal body are emitted in the gas passage and accelerated by an electric field, the electrons can be in contact with molecules flowing in the gas passage in a limited space (a space to form an ionization chamber) formed by the gas passage, and thus stable ionization are easily achieved by appropriately setting the cross-sectional area, cross-sectional shape, etc. of the gas passage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ionization apparatus and method used, for example, under atmospheric pressure.

  As a conventional ionization apparatus, there is an apparatus configured to irradiate a gas with low energy X-rays and perform ionization by photoionization.

  However, the ionization apparatus described above is suitable for ionizing a wide range of gases, but is inefficient for ionizing a local and small volume portion.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ionization apparatus and method capable of realizing highly efficient, stable and safe ionization.

  In order to achieve the above object, an ionization apparatus according to the present invention includes an X-ray tube and a metal thin film provided in contact with a gas flowing in a gas flow path, and the metal thin film is formed from the X-ray tube. X-rays are emitted to emit photoelectrons into the gas flow path (Claim 1).

  In the invention according to claim 1, the metal thin film is provided on the inner surface of a cylindrical metal tube, the space inside the metal tube is the gas flow path, and the side wall of the metal tube An X-ray transmission window for irradiating the metal thin film with X-rays from the X-ray tube may be provided (Claim 2). As the X-ray transmission window portion, for example, an X-ray transmission window made of mica (mica) is employed.

  In this case, a metal wire (a metal thin wire having a diameter of about 50 μm or less is preferable) that passes through the metal tube in a non-contact manner, and a voltage (several kV) for accelerating photoelectrons between the metal tube and the metal wire. It is more desirable to have a means for multiplying photoelectrons generated in the metal thin film by an electric field (high electric field) in an accelerated cascade.

  In order to achieve the above object, an ionization method according to the present invention ionizes the gas by the ionization apparatus according to any one of claims 1 to 3 (claim 4).

  According to the first to fourth aspects of the present invention, an ionization apparatus and method capable of realizing highly efficient and stable ionization can be obtained.

  That is, in the invention according to claim 1, since a configuration is adopted in which electrons generated when X-rays are applied to the metal thin film of the metal body are emitted into the gas flow path and the electric field is accelerated. In a limited space (a space forming an ionization chamber), and electrons and molecules flowing through the gas flow channel can be brought into contact with each other by appropriately setting the flow channel cross-sectional area and cross-sectional shape of the gas flow channel. Stable ionization can be easily realized.

  Moreover, in the invention according to claim 1, the configuration is simple, and downsizing and reduction in manufacturing cost can be achieved.

  In the invention which concerns on Claim 2, since a gas flow path is comprised by the metal pipe | tube with which the metal thin film was provided in the inner surface, a structure can be made very simple. In addition to this effect, the invention according to claim 3 is characterized in that the electrons generated in the metal tube are accelerated by the acceleration voltage, and the metal tube and the cylinder (consisting of a cylindrical metal tube) are made cylindrical. An electron cascade is generated by a concentrated electric field (high electric field) caused by the electrodes, and ionization efficiency by electron impact can be increased.

  In the invention according to claim 4, the above-described effects can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory view schematically showing an ionization apparatus according to a first embodiment of the present invention. As shown in this figure, the ionization apparatus according to this embodiment includes an X-ray tube 1 and a metal tube 2. And a metal wire (wire) 3 that is inserted through the metal tube 2 in a non-contact manner, and an application means 4 that applies a voltage across the metal tube 2 and the metal wire 3.

  The X-ray tube 1 has a known configuration in which a thermoelectron source and a target portion 1b are provided in a vacuum vessel having a window portion 1a, and further includes a thermoelectron generating power source 1f, a thermoelectron accelerating power source. (About 6 kV) 1c. The X-ray tube 1 in this embodiment generates soft X-rays (for example, X-rays having a quantum energy of about 2 to 4 keV or less) 5 by receiving electrons from an electron source in a vacuum vessel. The soft X-ray 5 is configured to go outward from the window portion 1a. Therefore, the X-ray tube 1 is a soft X-ray tube.

  Here, the window portion 1a is a window formed of a thin film made of a material (beryllium (Be) in this embodiment) having excellent X-ray transmission and sufficient strength.

  The thermoelectron source of the X-ray tube 1 includes a filament 1e and an electrode 1d for converging and accelerating electrons emitted from the filament. Note that an electron source having a cold cathode, for example, may be used instead of the electron source having a filament.

  The target portion 1b of the X-ray tube 1 has a target made of titanium (Ti) that emits soft X-rays 5 by electron collision, and an electrode that applies a potential to the target. The target may be made of another metal that generates characteristic X-rays in the soft X-ray region.

  The metal tube 2 is made of a cylindrical (cylindrical in the illustrated example) stainless steel, and the space inside the metal tube 2 is a gas flow path. In addition, a metal thin film 2a made of, for example, heavy metal is attached to the inner side surface of the metal tube 2 by an appropriate means (for example, vapor deposition) so that a gas (for example, a sample gas) flowing through the gas flow channel is in contact with the inner surface. Is granted. Furthermore, a window portion 1a of the X-ray tube 1 faces the side wall of the metal tube 2, and X-rays made of mica (mica) for irradiating the metal thin film 2a with soft X-rays 5 from the X-ray tube 1 A transmissive window portion 2b is provided.

  The X-ray transmissive window portion 2b is a window provided on the side wall of the metal tube 2 and is made of mica (mica) and has a small X-ray attenuation of about several μm. As a result, the metal pipe 2 becomes a closed gas flow path. The X-ray transmission window 2b is not a window, but a simple opening. The window 1a is hermetically connected to the opening, and the soft X-ray 5 is directly irradiated into the metal tube 2 (metal thin film 2a). Also good.

  A metal wire 3 (for example, a metal thin wire made of tungsten having a diameter of about 50 μm) is disposed so as to pass substantially through the central axis of the cylindrical metal tube 2, and a potential difference is applied across the metal wire 3 and the metal tube 2. The application means 4 is provided in FIG.

  Next, the operation of the ionization apparatus having the above-described configuration will be described together with the description of the ionization method according to the first embodiment.

  First, soft X-rays 5 are emitted from the window portion 1a of the X-ray tube 1 with a spread angle of, for example, about 150 °, reach the inside of the metal tube 2 from the X-ray transmission window portion 2b, and are irradiated onto the metal thin film 2a. The

  By this irradiation, photoelectrons are emitted from the metal thin film 2 a into the metal tube 2 (that is, in the gas flow path) and accelerated toward the metal wire 3. That is, the application of voltage across the metal tube 2 and the metal wire 3 by the applying means 4 is such that electrons emitted from the metal tube 2 are accelerated toward the metal wire 3.

  Furthermore, an electron multiplication effect can be expected by the electron cascade by adopting a thin wire for the metal wire 3 as the central electrode and sufficiently increasing the electric field strength in the gas flow path. Thereby, highly efficient ionization is achieved.

  Therefore, gas molecules (for example, sample molecules) in the gas flowing through the gas flow path inside the metal tube 2 are ionized by the electrons, and the gas molecules and electrons are separated in a limited space in the metal tube 2. Since they can be contacted, highly efficient and stable ionization is achieved.

  Furthermore, since the soft X-rays 5 collide with the gas gas before reaching the metal thin film 2a and exert a photoionization effect, the utilization efficiency of the irradiated soft X-rays 5 is high.

It is explanatory drawing which shows schematically the ionization apparatus which concerns on one embodiment of this invention.

Explanation of symbols

1 X-ray tube 2 Metal tube 2a Metal thin film 3 Metal wire 4 Application means 5 Soft X-ray

Claims (4)

  An X-ray tube and a metal thin film provided in contact with the gas flowing through the gas flow path are provided, and the metal thin film is irradiated with X-rays from the X-ray tube to emit photoelectrons into the gas flow path. An ionizer configured to:   The metal thin film is provided on an inner surface of a cylindrical metal tube, and a space inside the metal tube serves as the gas flow path, and an X-ray from the X-ray tube is formed on a side wall of the metal tube. The ionization apparatus of Claim 1 with which the X-ray transmissive window part for making the said metal thin film irradiate is provided.   A metal wire that is inserted through the metal tube in a non-contact manner, and an application unit that applies a photoelectron acceleration voltage across the metal tube and the metal wire, and the photoelectrons are accelerated by an electric field to generate cascade electrons. 2. The ionization apparatus according to 2.   An ionization method in which the gas is ionized by the ionization apparatus according to claim 1.