US1718849A - X-ray tube - Google Patents

X-ray tube Download PDF

Info

Publication number
US1718849A
US1718849A US691658A US69165824A US1718849A US 1718849 A US1718849 A US 1718849A US 691658 A US691658 A US 691658A US 69165824 A US69165824 A US 69165824A US 1718849 A US1718849 A US 1718849A
Authority
US
United States
Prior art keywords
cathode
anticathode
tube
ray tube
gas
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
US691658A
Other languages
English (en)
Inventor
Bouwers Albert
Willem Hendrik Van D Bakhuyzen
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
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 claimed from GB2486023A external-priority patent/GB228592A/en
Application filed by Philips Gloeilampenfabrieken NV filed Critical Philips Gloeilampenfabrieken NV
Application granted granted Critical
Publication of US1718849A publication Critical patent/US1718849A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/20—Selection of substances for gas fillings; Means for obtaining or maintaining the desired pressure within the tube, e.g. by gettering

Definitions

  • the present invention relates to improvements 1n incandescent cathode X-ray tubes.
  • Known tubes of this type are for example those constructed by Wehneltand Trenkle 5 (Fii'tzungsberichte der physikalisch shen Soziett, Erlangen 37,312 (1905)) and those constructed by Coolidge. i
  • the vacuum ⁇ in the X-ray tube of Coolidge according to his de- ⁇ scriptiomis to be as high as possible in order to avoid ionization.
  • the gas pressure in Coolidges tubes is about .l 0.00005 millinetres ot mercury, the upper limit of pressure being fixed at 0.0006 millimetres, thus much lower than the gas pressure in X-ray tubes the operation of which is based on gas ionization and in Which the gas I nessure varies between 0.001 and 0.01 millimetres of mercury.
  • the removal of the very last gas residues it has even been proposed to introduce into the X-ray tubes or' the Coolidge or zirconium, which uponheating, will combine with the said gas residues.
  • Incandescent cathode X-ray tubes are characterized by a gaseous filling of hydrogen, helium, or a mixture ot the said gases, said filling having a pressure such that no appreciable gas ionization occurs and the production ⁇ of positive y ions is practically eliminated.
  • the gaseous pressure Will be chosen higher than 0.0006 millimetres of 1ner cury.
  • Very good results have been obtained with X-ray tubes in which during operation, the field at the anticathode Was ver intensive. The more intensive the fieldy anticathode in such X-raytubes, the higher is the gas pressure at which gas ionizationl begins to have an appreciable influence.
  • the inventionl also comprises type suitable substances, for example thorium i at the Probably ionization due principally to ⁇ secondary electrons generated at the anticathode. Therefore by providing a large ⁇ field at thefiocal spot, the said seconda-ry electrons will be drawn back to the anticathodebeiore having an opportunity of ionizing molecules ofthe gaseous filling.
  • a A y ln ,order to ensure an intensive field at the anticathode,the X-ray tube may be soproportioned that the'distance between the cathode and the anticathode is very small.
  • the Xsray tube may alsobe so constructed that when connected to a high voltage circuit, the field is quite intensively concentrated before the anticathode and the entire potential difi terence between the cathode and anticathode is substantially before the anticathode and even very close before it.
  • X-ray tubes according to the invention will satisfy the condition thatfon supplying the high voltage between the cold cathode and the anticathode, no current Will pass through "the tube.
  • pl1enomena of ionization might be produced during the operation of the tube with the incan descent cathode, which phenomena would have a detrimental effect on the o )eration of the X-ray tube.
  • the present invention also comprises an incandescent cathode X-ray tube having a gaseous filling of hydrogen, helium,uor a 1 ⁇ niX- ture of said gases, the cathode hunk arranged" l.and ythe portion ofthe lsurface of the anticathode to be struck by theV cathode rays Will be placed in oradjacent t-he said aperture.
  • X-ray tubes according to thev invention have the advantage vthat they are better i adapted thanhigh vacuum X-ray tubes to be operated with alternating current Without the fanticathode being heated by the bombardment of electrons to sucha temperature r that a counter-current isproduced.
  • Figure l' shows an X-ray tube having a bulb 1,van incandescent cathode 2 and an anticathode 3.y
  • the incandescent cathode may be of,r tungsten andis connected to leading-in Wires 4, 4 sealed in the bulb.
  • rlhe cathode 2 is surrounded byla focussing device 5 for cathode rays; sa1d ⁇ device being 1n electrical conductlve connection to the cathode and supy ported by supportingwires 6, 6.
  • the said focussing' ⁇ device comprises a metal cylinder to which apmeta'l hemispherical element is fixed.
  • the antic'athode may be of tungsten fixedin copper which -may be sealed in the I" bulb by means of platinum. l ⁇ It is so arranged thatthe cathode rays can strike the antica-thode only over part of its surface.
  • a properly operating oil-pump is quite sufiic'ient for the object of theinvention. ⁇ While using such pump, the tube 'should be continuously Washed With the gas lwith which the X-ray tube isto be filled.
  • the lass of the bulb and the anti-cathmlc be fPreed from gases as the gases they generally contain, might injuriously influence the opera tion of the X-ray tube.
  • the gaseous filling is given the desired pressure.
  • some gas may disappear from the tube, thereby reducing the gas pressure.
  • the desired gas pressure can be restored, and thus a stat-e of affairs can be ensured in which the gas pressure no longer varies objectionably.
  • the gas pressure will be above 0.0000 milli-nietres of mercury, and lies preferably between 0.0006 and 0.02, within which range a pressure of from 0.001 to 0.01 generally yields the best results.
  • Figure 2 shows an X-ray tube with a met al envelope.
  • the incandescent cathode 0 is arranged within a metal vessel 7 to the wall of which is fixed a metal cover S provided with an aperture before which part of the surface of theanticathode 10 is located.
  • the metal ⁇ f'ossel is provided With a Window for the passage of the X-rays generated.
  • the said window comprises a glass cap 11 hermetically sealed to the metal vessel at 19, and in addition an annular metal plate 12 for example of iron is provided screening the X-rays and having the leadingin Wires for the incam'lescent cathmle fixed to it.
  • the X-ray tube is filled with hy drogen or helium of a pressure liietween 0.01 and 1 millimetres of mercury.
  • One leadingin Wire 13 for the incandescent cathode passes ⁇ through the metal plate 12 from which it is insulated and is sealed in the glass cap l1.
  • the other leading-in wire is consti tuted by the conductive connection o t the terminal lll, the metal plate l2 and tlfiecmetal envelope 7.
  • the cathode is made incandescent by the passage of an electric current supplied by a battery 17 with which aregulating resistance 18 is connected in series.
  • a metal cylinder 1G disposed before the weld l5 is sealed to the metal envelope 7 and serves to protect the weld l5 against bombarding electrons and thus against electrostatic charges.
  • the distance from the anticathode ⁇ to the .metal envelope 7, the metal cover 8 and the metal cylinder 1G so small throughout that at the gas pressure used there is no risk ol' a discharge occurring between the said metal parts when the tube is connected to a source ot high voltage.
  • the cathode rays emitted by the cathode can strike only a small ar-ea ot the anticathode, owing to the particular shape of wall and cover of the metal vessel and to the arrangement ol the antieathode in relation to the said cover.
  • the focal spot is found to have a diameter of some 2 millimetres only.
  • An X-ray tube comprising an envelope, cooperating electrodes therein one olf which has connections for heating it independently of the other, the space within said envelope being provided with a gaseous filling oi at least one of the two ⁇ elements oli' smallest atomic number having a pressure higher than 0.0006 mm. of mercury suoli that there does not occur appreciable ionization by collision during the operation of the tube.
  • the combination ot a cathode, an anode and an inelosing envelope provided with a gaseous illing of at least one of the two elements of' smallest atomic number having a pressure between 0.0006 and 0.02 mm. of mercury.
  • An incandescent cathode X-ray tube containing a gaseous filling of at least one oit the two elements of smallest atomic number having a pressure higher than 0.0006 min. of mercury such that no appreciable gas ionization occurs, and including an incandescent cathode and an anticathode, the distance between the anticathode and the incandescent cathode being very small.
  • An incandescent cathode X-ray tube containing a gaseous lilling oit at least one of the two elements of smallest atomic number having' a pressure higher than 0.0006 mm. oi: mercury such that no appreciable gas ionization occurs, and including a metal vessel having a wall which forms part of the outer envelope ot the tube, an incandescent cathode mounted within the metal vessel, and an anticathode separate from said vessel by an insulation capable of resisting the operating voltage to be supplied between the incandesn cent cathode and the anticathode.
  • An .incandescent cathode X-ray tube containing a gaseous filling oi? at least one of the two elements oi smallest atomic number having a pressure higher than 0.0006 mm. oit mercury such that the hydrogen is not appreciably ionized, and including a metal vessel having a wall which terms part of the outer envelope of the tube, a cathode mounted within the metal vessel, and an anticathode separated.
  • said vessel by an insulation capable ol resisting the operating voltage to be supplied between the cathode and the anticathode, said metal vessel being locally constrieted to form a small aperture for focusing the electrons passing therethrough and a portion of the surface of the anticathode designed to be struck by the cathode rays being placed adjacent the said aperture, whereby the cathode rays can strike only a small area of the anticathode.
  • An Xiay tube comprising an evacuated envelope, an anticathode and a double terminal cathode located in said envelope, and a gaseous filling of at least one of the two elements of smallest atomic number in said envelope under a pressure greater than 0.0000 mm. of mercury.
  • An X-ray tube oi the incandescent cathode type, having an envelope the outer Wall of which is partly of metal, and compris-l electrically connected with the incandescent ing a gaseous filling of at least one of the two cathode being very small.

Landscapes

  • X-Ray Techniques (AREA)
US691658A 1923-09-28 1924-02-09 X-ray tube Expired - Lifetime US1718849A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1718849X 1923-09-28
GB2486023A GB228592A (en) 1923-10-05 1923-10-05 Improvements in and relating to incandescent cathode x-ray tubes

Publications (1)

Publication Number Publication Date
US1718849A true US1718849A (en) 1929-06-25

Family

ID=26257337

Family Applications (1)

Application Number Title Priority Date Filing Date
US691658A Expired - Lifetime US1718849A (en) 1923-09-28 1924-02-09 X-ray tube

Country Status (4)

Country Link
US (1) US1718849A (enrdf_load_stackoverflow)
DE (1) DE568306C (enrdf_load_stackoverflow)
FR (1) FR575760A (enrdf_load_stackoverflow)
NL (1) NL24985C (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2683223A (en) * 1952-07-24 1954-07-06 Licentia Gmbh X-ray tube
US2836747A (en) * 1955-03-28 1958-05-27 Dunlee Corp X-ray tube cathode

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2683223A (en) * 1952-07-24 1954-07-06 Licentia Gmbh X-ray tube
US2836747A (en) * 1955-03-28 1958-05-27 Dunlee Corp X-ray tube cathode

Also Published As

Publication number Publication date
NL24985C (enrdf_load_stackoverflow)
DE568306C (de) 1933-01-17
FR575760A (enrdf_load_stackoverflow) 1924-08-06

Similar Documents

Publication Publication Date Title
US1211092A (en) X-ray tube.
US1203495A (en) Vacuum-tube.
US4075526A (en) Hot-cathode x-ray tube having an end-mounted anode
US1355126A (en) X-ray tube
US1949347A (en) Electric discharge tube
US2991387A (en) Indicator tube
US2518879A (en) Hydrogen thyratron
US2201720A (en) Thermionic cathode structure
US1626465A (en) X-ray tube
US3264511A (en) Glow discharge device
US2416661A (en) Dispenser type cathode electric discharge device
US1718849A (en) X-ray tube
US3155849A (en) Thermionic converter
US1920601A (en) Electron discharge device
US3906275A (en) Electric lamp with electrolysis preventing apparatus
US1945746A (en) Electron discharge device with indirectly heated cathode
US1878338A (en) Gaseous conduction apparatus
US2129015A (en) Braun tube
US1715152A (en) X-ray tube
US1632080A (en) Electric discharge device
US1211091A (en) Cathode-ray device.
US1760525A (en) Rectifier
US1903144A (en) Rectifying tube
US1591129A (en) Electric discharge tube
US1945639A (en) Discharge tube