# US 2013/0154658 A1 · Discharge Ionization Current Detector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154658 A1 - Document ID: US20130154658A1 - Status: Published application - Kind: A1 - Application number: 13/714,070 - Filed: 2012-12-13 - Published: 2013-06-20 - Earliest claimed: 2011-12-16 - Assignees: Shimadzu Corporation - Inventors: Kei SHINADA; Shigeyoshi HORIIKE - Web page: https://patentgrep.com/patent/US20130154658A1 ## CPC - G01N 27/70: and measuring current or voltage - G01N 27/60: by investigating electrostatic variables {, e.g. electrographic flaw testing (G01N27/007 takes precedence)} - G01N 27/66: and measuring current or voltage - G01N 30/64: Electrical detectors - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A discharge ionization current detector that is durable and produced at a low cost is provided. An electrode structure of a dielectric-coated metal tube, with an insulator-coated metal wire included therein, is inserted from above into a first gas passage including a dielectric tube. The metal tube is connected to the ground on the upstream side of the first gas passage. One end of the metal wire is extracted from the upstream side of the first gas passage to the outside and connected to a bias power source. An area is not covered with the insulator is provided at the other end of the wire. This area is arranged in a second gas passage, which extends from the downstream end of the first gas passage. A metal electrode consisting of a flanged metal tube is placed in the second gas passage and connected to an ionization current detecting circuit 34. ## Claims ### Claim 1 A discharge ionization current detector comprising: a) a first gas passage through which a plasma generation gas is passed, and in which a plasma is generated from the plasma generation gas with an electric discharge; b) a second gas passage extending from the downstream end of the first gas passage, in which a sample component in a sample gas supplied to the second gas passage is ionized by the action of the plasma; c) a current detector for detecting an electric current due to the ionized sample component; d) a dielectric tube forming at least a portion of the first gas passage; e) a plasma generating excitation electrode attached to an outer circumference of the dielectric tube; f) a metal electrode provided in the second gas passage so as to come in contact with the sample gas; and g) an electrode structure provided in the first gas passage, wherein: the electrode structure includes a metal tube covered with a dielectric material and a metal wire covered with an insulating material and inserted in the metal tube; the metal tube has one end electrically connected to a ground on an upstream side of the first gas passage and another end reaching at least a point facing the plasma generating excitation electrode; one end of the metal wire is extracted from the upstream side of the first gas passage to an outside, and another end thereof is provided with an area that is not covered with the insulating material, the area being located within the second gas passage so as to come in contact with the sample gas; and either the aforementioned one end of the metal wire or the metal electrode is connected to a bias power source, and the remaining one is connected to an ionization current detecting circuit. ### Claim 2 (depends on 1) The discharge ionization current detector according to claim 1, wherein: the metal electrode has a hollow cylindrical portion with both ends open and a projecting portion extending outward in a radial direction from an outer circumference of the cylindrical portion, the cylindrical portion being arranged within the second gas passage so as to surround the area of the metal wire which is not covered with the insulating material, and the projecting portion being extracted to an outside of the second gas passage on a downstream side of the aforementioned area and connected to the bias power source or the ionization current detecting circuit. ### Claim 3 (depends on 1) The discharge ionization current detector according to claim 1, wherein: an area which is not covered with the dielectric material is provided in said another end portion of the metal tube, and this area is located downstream from the plasma generating excitation electrode and upstream from the area of the metal wire which is not covered with the insulating material. ### Claim 4 (depends on 2) The discharge ionization current detector according to claim 2, wherein: an area which is not covered with the dielectric material is provided in said another end portion of the metal tube, and this area is located downstream from the plasma generating excitation electrode and upstream from the area of the metal wire which is not covered with the insulating material. ### Claim 5 A discharge ionization current detector comprising: a) a first gas passage through which a plasma generation gas is passed, and in which a plasma is generated from the plasma generation gas with an electric discharge; b) a second gas passage extending from the downstream end of the first gas passage, in which a sample component in a sample gas supplied to the second gas passage is ionized by the action of the plasma; c) a current detector for detecting an electric current due to the ionized sample component; d) a dielectric tube forming at least a portion of the first gas passage; e) a plasma generating excitation electrode attached to an outer circumference of the dielectric tube; and f) a plurality of electrode structures inserted in the first gas passage, wherein: each of the electrode structures includes a metal tube covered with a dielectric material and a metal wire covered with an insulating material and inserted in the metal tube; the metal tube has one end electrically connected to a ground on an upstream side of the first gas passage and another end reaching at least a point facing the plasma generating excitation electrode; one end of the metal wire is extracted from the upstream side of the first gas passage to an outside, and another end thereof is provided with an area which is not covered with the insulating material, the area being located within the second gas passage so as to come in contact with the sample gas; and one end of the metal wire included in at least one of the electrode structures is connected to a bias power source, and one end of the metal wire included in each of another electrode structure or structures is connected to an ionization current detecting circuit. ### Claim 6 (depends on 5) The discharge ionization current detector according to claim 5, wherein: an area which is not covered with the dielectric material is provided in said another end portion of the metal tube, and this area is located downstream from the plasma generating excitation electrode and upstream from the area of the metal wire which is not covered with the insulating material.