US2805351A - Magnet system for producing a magnetic field - Google Patents

Magnet system for producing a magnetic field Download PDF

Info

Publication number
US2805351A
US2805351A US378602A US37860253A US2805351A US 2805351 A US2805351 A US 2805351A US 378602 A US378602 A US 378602A US 37860253 A US37860253 A US 37860253A US 2805351 A US2805351 A US 2805351A
Authority
US
United States
Prior art keywords
magnet
pole shoes
magnetic field
producing
magnet system
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
US378602A
Other languages
English (en)
Inventor
Niklas Wilfrid Franz Ko Johann
Jan Van Wijngaarden
Alphonsus Petrus Van Rooy
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.)
US Philips Corp
North American Philips Co Inc
Original Assignee
US Philips Corp
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
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US2805351A publication Critical patent/US2805351A/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
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/84—Traps for removing or diverting unwanted particles, e.g. negative ions, fringing electrons; Arrangements for velocity or mass selection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/54—Arrangements for centring ray or beam

Definitions

  • This invention relates to magnet systems for producing a magnetic field in a space traversed by a beam of electrically charged particles, the systems comprising a magnet and two pole pieces of magnetically soft material situated one at each side of the beam.
  • cathode-ray tubes for instance for oscillography or television purposes, mass spectrographs and amplifying tubes.
  • mass spectrographs and amplifying tubes.
  • a cathode-ray tube has hereinafter been chosen as an example without, however, the invention being limited to this type of tubes.
  • a magnet system comprising a magnet having connected to it two pole shoes situated one at each side of the space traversed by the electron beam are known for this purpose.
  • a magnet system has been described, which comprises a small permanent magnet situated adjacent the neck of the cathoderay tube, the pole shoes secured to the magnet consisting of a narrow strip of soft iron provided with two ends. Seen from the magnet, said pole shoes first extend parallel, then diverge and finally extend parallel again, the neck of the cathode-ray tube being located between the two last-mentioned parallel ends.
  • the magnetic field at the electron beam is naturally determined by the magnetic lines of force issuing from the magnet and the pole shoes. It has been found that the magnetic configuration of the field in known constructions involves very troublesome astigmatism of the beam.
  • the icon astigmatism is to be understood to mean the phenomenon that the cross-sectional area of an initially cylindrical beam in a plane at right angles to the main direction of the particles of the beam is ellipsoidal.
  • Researches on which the invention is base have revealed that the main cause of said astigmatism is that the magnetic field strength, measured on a line through the beam midway between the pole shoes, decreases materially accordingly as the distance from the magnet increases.
  • the pole shoes have a certain reluctance.
  • the present invention provides a magnet system permitting the astigmatism of the beam to be materially reduced.
  • a magnet system according to the invention for producing a magnetic field in a space traversed by a beam of electrically charged particles comprises a magnet having connected to it two pole shoes of magnetically soft material situated one at each side of the beam and extending substantially in a plane at right angles to the beam, the system having the feature that the reluctance of the pole shoes decreases from one half of the length of the poleshoes onwards, towards their free' ends seen from the magnet.
  • the decrease in reluctance is obtainable in several different manners.
  • the pole shoes consist of strip-shaped material, that is to say strips of uniform thickness throughout their length, whose broad sides face the beam, the width of the pole shoes must increase from one half of their length onwards.
  • the width of the pole shoes is uniform throughout their length but their thickness increases.
  • the permeability per unit volume increases from one half of the length of the pole shoes onwards.
  • the reluctance may be caused to diminish from the magnet onwards, instead of diminishing from one half of the length of the pole shoes onwards. This yields in many cases an additional decrease in astigmatism.
  • the magnet system is preferably symmetrical relatively to a plane through the beam and the centre of gravity of the magnet.
  • a permanent magnet is used.
  • an electro-magnet may be used.
  • FIG. 1 represents diagrammatically a magnet frame system according to the invention, in which the pole shoes consist of strip-shaped material,
  • Fig. 2 is a side view of the magnet system shown in Fig. 1,
  • Fig. 3 is a graphical representation of the field-strength distribution obtained by means of a magnet frame shown in Figs. 1 and 2, and
  • Fig. 4 shows diagrammatically a magnet system according to the invention, in which the pole shoes are of uniform width throughout their length.
  • the reference numeral 1 denotes the cross-section of the neck of a cathode-ray tube producing an electron beam 2. Laterally of the neck 1 are provided two strip-shaped pole shoes 3, 4 connected at 5 and 6 respectively to the permanent magnet 7 and, as may be seen from Fig. 2, increasing in width from half their length onwards.
  • the magnetic field strength on the line 3-8 passing through the electron beam 2 and the centre of gravity of the magnet 7 may be seen from the graph shown in Fig. 3, wherein the field strength in Gauss, obtained by means of a given magnet 7, is plotted on the abscissa, the distances on the line 8-8 being plotted on the ordinate.
  • the field strength on said line varies in accordance with the curve 9.
  • Fig. 4 shows a magnet system yielding approximately the same distribution of the field strength as the system shown in Fig. 1.
  • the pole shoes 11 and 12 are of uniform width but their thickness increases from the magnet 13 onwards.
  • a magnet system comprising a pair of substantially parallel spaced magnetically soft pole shoes, and means interconnecting one pair of opposed ends of said shoes for producing a magnetic field between said shoes, each of said shoes having a portion at about its center with a predetermined reluctance and a portion at the end thereof remote from the producing means of lesser reluctance,
  • a magnet systcm comprising a pair of approximately parallel spacedstrip-shaped soft ferromagnetic members, and a permanent magnet interconnecting one pair of opposed ends of said members, the reluctance of each of said members varying continuously and uniformly from a lower value to a higher value between the end thereof remote from the magnet and a portion thereof lying close to the magnet.
  • an envelope means Within said envelope for producing a beam of electrically charged particles in a given path, and a magnet system surrounding said envelope for producing a magnetic field therein, said system including a pair of magnetically soft pole shoes each disposed on one side of said beam and extending substantially in a plane at right angles tothe beam path, and a magnet interconnecting one pair of ends of said pole shoes, the center of said pole shoes being approximately at the center of said beam, the reluctance of each of the pole shoes gradually decreasing from at least about its center to the end thereof remote from the magnet.

Landscapes

  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Particle Accelerators (AREA)
US378602A 1952-09-10 1953-09-04 Magnet system for producing a magnetic field Expired - Lifetime US2805351A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL758930X 1952-09-10

Publications (1)

Publication Number Publication Date
US2805351A true US2805351A (en) 1957-09-03

Family

ID=19825356

Family Applications (1)

Application Number Title Priority Date Filing Date
US378602A Expired - Lifetime US2805351A (en) 1952-09-10 1953-09-04 Magnet system for producing a magnetic field

Country Status (5)

Country Link
US (1) US2805351A (fr)
DE (1) DE927588C (fr)
FR (1) FR1088646A (fr)
GB (1) GB758930A (fr)
NL (2) NL172387B (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2935691A (en) * 1952-10-18 1960-05-03 Bbc Brown Boveri & Cie Process and apparatus to conduct out particles accelerated in an induction accelerator
US2956198A (en) * 1955-06-10 1960-10-11 Bell Telephone Labor Inc Traveling wave tubes
US20090001043A1 (en) * 2006-02-08 2009-01-01 Fabio Benetti Bottle, in Particular Adapted to Contain Beverages

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2264567A (en) * 1938-11-24 1941-12-02 Fernseh Ag Deflecting device
US2539156A (en) * 1949-01-19 1951-01-23 Tele Tone Radio Corp Ion trap magnet
US2552342A (en) * 1949-11-17 1951-05-08 Clarostat Mfg Co Inc Magnetic structure for use in ion-traps

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2264567A (en) * 1938-11-24 1941-12-02 Fernseh Ag Deflecting device
US2539156A (en) * 1949-01-19 1951-01-23 Tele Tone Radio Corp Ion trap magnet
US2552342A (en) * 1949-11-17 1951-05-08 Clarostat Mfg Co Inc Magnetic structure for use in ion-traps

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2935691A (en) * 1952-10-18 1960-05-03 Bbc Brown Boveri & Cie Process and apparatus to conduct out particles accelerated in an induction accelerator
US2956198A (en) * 1955-06-10 1960-10-11 Bell Telephone Labor Inc Traveling wave tubes
US20090001043A1 (en) * 2006-02-08 2009-01-01 Fabio Benetti Bottle, in Particular Adapted to Contain Beverages
US7997434B2 (en) * 2006-02-08 2011-08-16 Fabio Benetti Bottle, in particular adapted to contain beverages

Also Published As

Publication number Publication date
NL80933C (fr)
GB758930A (en) 1956-10-10
FR1088646A (fr) 1955-03-09
DE927588C (de) 1955-05-12
NL172387B (nl)

Similar Documents

Publication Publication Date Title
US2698917A (en) Magnetic circuit comprising a ferromagnetic part having high permeability and a substantially flat, thin permanent magnet
US2188579A (en) Cathode ray tube, more particularly for television purposes
US2812470A (en) Periodic focusing in traveling wave tubes
GB779733A (en) Improvements relating to electron-discharge devices
US2522872A (en) Device for controlling the path of travel of electrons in cathoderay tubes
US2797360A (en) Travelling wave amplifiers
Tien Focusing of a long cylindrical electron stream by means of periodic electrostatic fields
US2805351A (en) Magnet system for producing a magnetic field
US3020434A (en) Self shielding electron gun and cathode ray tube system including same
US2843775A (en) Electron tube magnetic focusing device
US2900557A (en) Traveling wave directional attenuator
US2936408A (en) Permanent magnets
US2721995A (en) Cathode ray tube shield structures
US2515305A (en) Electromagnet
US3064096A (en) Contact alternator
US2968807A (en) Ferro-magnetic core antenna
US2793324A (en) Ionic triode speaker
GB1414240A (en) Mislanding corrector for colour television cathode ray tubes
US3529197A (en) Electron tube device provided with a periodic permanent magnet focussing means and magnetic flux temperature compensating means
US2241105A (en) Sound translating device
US2976454A (en) High frequency energy interchange device
US2563525A (en) Image size control device for
US2940020A (en) Focusing magnet for long electron beams
US2579273A (en) Magnetic lens for electron optical systems
US2172530A (en) Cathode bay tube