US2652532A - Electrical vapor detector - Google Patents

Electrical vapor detector Download PDF

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Publication number
US2652532A
US2652532A US305884A US30588452A US2652532A US 2652532 A US2652532 A US 2652532A US 305884 A US305884 A US 305884A US 30588452 A US30588452 A US 30588452A US 2652532 A US2652532 A US 2652532A
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US
United States
Prior art keywords
cathode
electrode
anode
finely divided
filament
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US305884A
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English (en)
Inventor
Paul D Zemany
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE522260D priority Critical patent/BE522260A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US305884A priority patent/US2652532A/en
Priority to FR65090D priority patent/FR65090E/fr
Priority to GB23297/53A priority patent/GB728114A/en
Application granted granted Critical
Publication of US2652532A publication Critical patent/US2652532A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/68—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas
    • G01N27/70—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas and measuring current or voltage
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/005—Gas-filled transit-time tubes

Definitions

  • an electrical discharge device under conditions which permit the substance to induce positive ion :formation at a more positively charged and heated electrode, the positive ions so formed being collected by a negatively charged electrode to produce an indicating current which increases with the concentration of the substance.
  • Devices of this type have been found to be qualitatively selective at atmospheric or greater presxsures and in vacua; that is, they respond only to certain types of substances such as the al- .kali metals or other substances having ionization potentials less than the electron work function of the electrodes, the halogens or compounds 20f either. alkali metals and their compounds, the ion for- :mation apparently occurs by ionization of the substance when it comes into contact with the For certain substances such as the more positively charged and heated electrode.
  • the substance appears to cause ion formation only in the presence of what might be called sensitizing materials such as the alkali metals and their compounds, and it further appears in this case that the sensitizing materials themselves are actually ionized to afford the desired positive ion current.
  • a principal object of my invention is, therefore, to provide an electrical vapor detector of the type described in which amplification of the small ion currents is easily obtained. Another object of my invention is to provide low signal-to-noise ratio amplification of ion currents in an electrical vapor detector. A further object of my invention is to provide an electrical vapor detector in which amplification of the ion currents is obtained with a minimum of external interference. A still further object of my invention is to provide an electrical vapor detector in which the more positively charged and heated electrode may be easily replaced.
  • apparatus for detecting the presence of a finely divided substance comprising an electrical discharge device which includes a cathode, a filament for heating the cathode to cause the emission of electrons therefrom, and an anode for receiving electrons emitted from the cathode.
  • an electrical discharge device which includes a cathode, a filament for heating the cathode to cause the emission of electrons therefrom, and an anode for receiving electrons emitted from the cathode.
  • Fig. 1 is a, partly brokenaway and partly sectionalized view of vapor detector apparatus according to my invention
  • Fig. 2 is an alternative embodiment in which identical reference characters are utilized to in dicate elements similar to those illustrated in Fig. 1.
  • the apparatus comprises an electrical discharge device I which includes a cathode 2, a filament 3, a control electrode 4 and an anode 5 suitably enclosed by an evacuated envelope 6.
  • Cathode 2 is formed of a cylinder 1 which extends through envelope I as shown in order that a. finely divided substance to be detected may be introduced therewithin from an external source.
  • the interior of cylinder 1 is isolated from the evacuated interior of envelope l by a suitable end-closure member 8.
  • various lead and support members 9, [0, ll, [2, l3 and I4 can be positioned as illustrated.
  • Electron emission from cathode 2 is obtained by means of a conventional thermionically emissive coating [9 upon the exterior surface of cylinder 1.
  • Circuit interconnections enabling operation of electrical discharge device I as a detector for finely dvided substances comprise an anode load resistor 20 connected in series with a current responsive instrument 2
  • Filament 3 and cathode 2 can be heated to desired temperatures by means of a transformer 23, the primary winding of which is supplied from a suitablesource of alternating current 24.
  • Cathode cylinder 1 is maintained at a negative potential with respect to filament 3 by a source of direct voltage 25 which is connected in circuit with a resistor 26 to cathode lead I3,
  • the secondary winding offilament transformer 23 can be maintained at ground potential as illustrated.
  • Control electrode 4 is connected to the common interconnection of source Ziand resistor 2t througha bias voltage source 21.
  • the finely divided substance to be detected . is introduced into the interior of cathode cylinder 1, w l ,1e reby positive ion formation by filament 3. is induced.
  • the positive ions thus formed are a collected upon the interior of the relatively negativelyeharged cathode cylinder 1 and cause a corresponding current to now through resistor 2 3 betweenfilament 3 and cathode cylinder 1.
  • This current fiow caused by the collection of positive ions upon cathode cylinder 1 varies the potential difference across resistor 26 and hence varies the potential of cathode 2 with respect to control. electrode 4.
  • cathode cylinder .1 is heated to a desired temperature by filament 3 such that electron emission occurs from coating I3, the variation in the cathode-to-control electrode potential difference produces an amplified variation in theelectron current flowing in the anode circuit of the discharge device.
  • These amplified variations in the electron current are indicated by current'responsive instrument ,2], whereby the presence of the finely divideld Substance is detected.
  • filament 3 is preferably formed of a, material such as tungsten or platinum coated witha refractory coating of an oxide of one of thejmaterials disclosed andclaimed in my concurrently filed application, Serial No. 305,883.
  • the oxides which can be employed are the oxides of aluminum, titanium, beryllium, thorium, magnesium, molybdenum,iron, calcium, manganese, silicon, cobalt, nickel and the rare earths, Even in their most purified available forms, these oxides contain at least a few hundredths of a per cent of alkali impurities which evaporate from the filament coating as alkali ions during operation of the apparatus to detect halogens. .With a thin coating (e. g., several mils in thickness) of an oxide of one of these materials upon filament 3, sufiicient current should be passed from filament transformer 23 through filament 3 to heat the coating to a temperature ranging from about 700 C. to about 1300 Cl'or higher.
  • the above oxides "apparently possess semiconductor properties which allow them to serve as insulators for the direct flow of current between filament 3 4 and cathode cylinder 1 but still permit the evapo-' ration of alkali ions in the presence of halogen vapors. Therefore, when the oxides of the aboveidentified materials are employed as coatings for filament 3, it is unnecessary to take special precautions to prevent the short-circuiting of filament 3 to cathode cylinder 1. It is not essential that filament 3 .have'the twisted configuration illustrated in Fig.
  • filament 3 may be constructed of a thin uncoated strip or cylinder of platinum or other metals which contain sufiicient alkali impurities to serve as emitters of positive ions in the presence of halogen vapors.
  • controlelectrode 4 and its associated circuit may be omitted whereupon the changes in anode current due to variations in the anodeto-cathode potential diiferencecan serveto indicate the presence of the finely divided substance.
  • electrodes. in addition to control electrode4,j'ma'y be used to achieve 'desired'ci'rcult characteristics; for example, tetrode, pento'de, dual triode, etc., electrode structures can be utilized.
  • the apparatus of theinv'e'ntionca n be employed to detect a finely divided substance in an evacuated system or at atmospheric or -higher"pressures.
  • the substance to bedetecte'd' may be circulated throughcatho'de cylinder? at atmospheric or higher pressures' or it may be permitted to diifuse intoc'athode cylinder! "from a vacuum system connected thereto.
  • the forcing of gaseous media containing the finely divided substance to be detected through cathode cylinder 1 can-be facilitated by the removal of end-closure member 8- and the continuance of cathode cylinder 1 through envelope fi.
  • envelope 3 must 'be sealed'tothe exteriorof cathode cylinder 'in'order that a'vacuum may be'maintained within the envelope.
  • Fig.2 'there 'is shown a1ra1ternative"em bodiment of the"electricaldischarge device ofmy invention whichfa'cflitates ready removal-and replacement of filament 3.
  • -As' illustrated, ends 15 and 'l6of filament" 3 extend through cylinder 1 which is terminated in a convenient location by a sealportion 30. Ends 15 and l 6 are sealed along with leads H a'nd 'IZ'intO a press seal-3
  • the finely divided substance can beintroduoedto'rcylinder I "through aside arm 33. Accessto'filament 3 'iseasily' obtained by merely removing *seal' 3 l and sealportion 32, from seal portion 30.
  • Apparatus for detecting the presence of a finely divided substance comprising an electrical discharge device which includes a cathode, an electrode for heating said cathode to cause the emission of electrons therefrom and an anode for receiving electrons emitted from said cathode, means for maintaining said anode at a positive potential with respect to said cathode and said cathode at a negative potential with respect to said electrode, said cathode, said electrode and said anode being arranged such that contact of the finely divided substance with said electrode induces the formation of positive ions which are collected by said cathode, means for causing the potential of said cathode to vary in response to the collection of positive ions thereby, and means for indicating changes in the electron current between said cathode and said anode caused by the variations in said cathode potential, whereby said changes in the electron current serve to detect the presence of the finely divided substance.
  • Apparatus for detecting the presence of a finely divided substance comprising an electrical discharge device which includes a cathode, an electrode for heating said cathode to cause the emission of electrons therefrom, a control electrode and an anode for receiving electrons emitted from said cathode, means for maintaining said anode at a positive potential with respect to said cathode, said cathode at a negative potential with respect to said heating electrode and said control electrode at a desired control potential with respect to said cathode, means for bringing a quantity of the finely divided substance into contact with said heating electrode to induce the formation of positive ions which are collected by said cathode, means for causing the control electrode to cathode potential difference to vary in response to the collection of positive ions by said cathode, and means for indicating changes in the electron current between said cathode and said anode caused by the variations in said control electrode to cathode potential difference, whereby said changes in the electron current serve to detect the presence of the finely divided substance
  • Apparatus for detecting the presence of a finely divided substance comprising an electrical discharge device which includes a cathode, an electrode for heating said cathode to cause the emission of electrons therefrom, a control electrode and an anode for receiving electrons emit-, ted from said cathode, a first circuit connected between said anode and said cathode including a load resistor and a source of direct voltage for maintaining said anode at a positive potential with respect to said cathode, a second circuit connected between said cathode and said heating electrode including a resistor and a source of direct Voltage for maintaining said cathode at a negative potential with respect to said heating electrode, means for maintaining said control electrode at a desired control potential with re- 6 spect to said cathode, means for bringing a duantity of the finely divided substance into contact with said heating electrode to induce the formation of positive ions which are collected by said cathode and cause a current to flow insaid second circuit whereby said control potential is varied
  • An electrical discharge device for detecting the presence of a finely divided substance comprising a cathode and an anode disposed within an evacuated envelope, said cathode including a hollow electrode which extends through the wall of said envelope to provide a means for introducing a quantity of the finely divided substance into the interior of said hollow electrode, and an electrode adapted for heating to an elevated temperature and disposed within said hollow electrode for causing in the presence of the finely divided substance the formation of positive ions which may be collected upon said cathode and further for heating said cathode to an elevated temperature, whereby electrons may be emitted from said cathode and received by said anode in dependence upon the number of positive ions collected by said cathode.
  • An electrical discharge device as in claim 5 which further comprises a control electrode disposed within said envelope between said cathode and said anode.
  • Apparatus for detecting the presence of a finely divided substance comprising an electrical discharge device which includes a cathode, a control electrode, an electrode forheating said cathode to cause the emission of electrons therefrom, an anode for receiving electrons emitted from said cathode and an evacuated envelope enclosing said anode, said control electrode, said heating electrode and at least a portion of said cathode, said cathode including a hollow electrode which extends through the Wall of said envelope, means for maintaining said anode at a positive potential with respect to said cathode, said cathode at a negative potential with respect to said heating electrode and said control electrode at a desired control potential with respect to said cathode, means for introducing a quantity of the finely divided substance into said hollow electrode to induce the formation of positive ions which are collected by said cathode, means for causing the control electrode to cathode potential difference to vary in response to the collection of positive ions by said cathode, and means for

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Pathology (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US305884A 1952-08-22 1952-08-22 Electrical vapor detector Expired - Lifetime US2652532A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE522260D BE522260A (en(2012)) 1952-08-22
US305884A US2652532A (en) 1952-08-22 1952-08-22 Electrical vapor detector
FR65090D FR65090E (fr) 1952-08-22 1953-08-19 Détecteur électrique perfectionné de gaz, vapeurs, fumées et corps analogues
GB23297/53A GB728114A (en) 1952-08-22 1953-08-24 Improvements in and relating to electrical vapour detectors

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US305884A US2652532A (en) 1952-08-22 1952-08-22 Electrical vapor detector

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US2652532A true US2652532A (en) 1953-09-15

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US305884A Expired - Lifetime US2652532A (en) 1952-08-22 1952-08-22 Electrical vapor detector

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BE (1) BE522260A (en(2012))
FR (1) FR65090E (en(2012))
GB (1) GB728114A (en(2012))

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2814574A (en) * 1954-07-06 1957-11-26 Raytheon Mfg Co Black coatings for metal parts and methods for forming such coatings
US2879184A (en) * 1956-03-30 1959-03-24 Gen Electric Method of rendering titanium dioxide films electrically conductive
US2946914A (en) * 1958-06-16 1960-07-26 Stirling A Colgate Apparatus for producing and manipulating plasmas
US3991360A (en) * 1975-05-16 1976-11-09 General Electric Company Sensor assembly for a halogen gas leak detector
US5301537A (en) * 1991-05-31 1994-04-12 W. C. Wood Company Limited Method for detecting halocarbon refrigerant leaks by usage of a continually heated mass spectrometer
US20100120611A1 (en) * 2006-08-29 2010-05-13 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Catalytically active component for thermal ionization detectors for the detection of halogen-containing compounds and process for producing an oxide-ceramic material for the component
USRE42192E1 (en) * 2001-12-13 2011-03-01 The University Of Wyoming Research Corporation Volatile organic compound sensor system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2147732B (en) * 1983-10-07 1987-11-04 English Electric Valve Co Ltd Improvements in or relating to travelling wave tubes

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1356687A (en) * 1920-10-26 Method and apparatus for measuring gas-pressures
US2550498A (en) * 1947-06-14 1951-04-24 Gen Electric Method and apparatus for electrically detecting vapors and the like
US2652586A (en) * 1951-06-26 1953-09-22 Elmer F Ramsberger Curtain rod bracket and ring

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1356687A (en) * 1920-10-26 Method and apparatus for measuring gas-pressures
US2550498A (en) * 1947-06-14 1951-04-24 Gen Electric Method and apparatus for electrically detecting vapors and the like
US2652586A (en) * 1951-06-26 1953-09-22 Elmer F Ramsberger Curtain rod bracket and ring

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2814574A (en) * 1954-07-06 1957-11-26 Raytheon Mfg Co Black coatings for metal parts and methods for forming such coatings
US2879184A (en) * 1956-03-30 1959-03-24 Gen Electric Method of rendering titanium dioxide films electrically conductive
US2946914A (en) * 1958-06-16 1960-07-26 Stirling A Colgate Apparatus for producing and manipulating plasmas
US3991360A (en) * 1975-05-16 1976-11-09 General Electric Company Sensor assembly for a halogen gas leak detector
US5301537A (en) * 1991-05-31 1994-04-12 W. C. Wood Company Limited Method for detecting halocarbon refrigerant leaks by usage of a continually heated mass spectrometer
US5490413A (en) * 1991-05-31 1996-02-13 Atkinson; John A. Method and apparatus for detecting refrigerant leaks
USRE42192E1 (en) * 2001-12-13 2011-03-01 The University Of Wyoming Research Corporation Volatile organic compound sensor system
US20100120611A1 (en) * 2006-08-29 2010-05-13 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Catalytically active component for thermal ionization detectors for the detection of halogen-containing compounds and process for producing an oxide-ceramic material for the component
US8618018B2 (en) * 2006-08-29 2013-12-31 Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. Catalytically active component for thermal ionization detectors for the detection of halogen-containing compounds and process for producing an oxide-ceramic material for the component

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Publication number Publication date
FR65090E (fr) 1956-01-26
BE522260A (en(2012))
GB728114A (en) 1955-04-13

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