US3509504A - Magnetic focusing system - Google Patents
Magnetic focusing system Download PDFInfo
- Publication number
- US3509504A US3509504A US711448A US3509504DA US3509504A US 3509504 A US3509504 A US 3509504A US 711448 A US711448 A US 711448A US 3509504D A US3509504D A US 3509504DA US 3509504 A US3509504 A US 3509504A
- Authority
- US
- United States
- Prior art keywords
- focusing system
- magnetic
- sleeve
- magnetic focusing
- temperature
- 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
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/02—Electrodes; Magnetic control means; Screens
- H01J23/08—Focusing arrangements, e.g. for concentrating stream of electrons, for preventing spreading of stream
- H01J23/087—Magnetic focusing arrangements
- H01J23/0873—Magnetic focusing arrangements with at least one axial-field reversal along the interaction space, e.g. P.P.M. focusing
Definitions
- a magnetic focusing system comprising annular ferrite pieces having polarities alternating from one piece to the next, spaced by pole pieces and forming a cylindrical sleeve; and a further cylindrical sleeve of magnetic material positioned within said first mentioned sleeve for shunting said pole pieces, said further sleeve being arranged for receiving that portion of a travelling wave tube through which a delay line extends.
- FIG. 3 i an explanatory graph.
- the part of the tube containing the helical line 3 is located within a magnetic focusing system which comprises a cylindrical sleeve 4 placed within another sleeve formed of annular ferrlte magnets 5, magnetized in the direction parallel to the tube axis, whose polarities are 3,509,504 Patented Apr. 28, 1970 alternately inverted so that they are NS, SN, NS, SN etc., and between which annular pole pieces 6 with a T shaped section are inserted.
- FIG. 2 illustrates on an enlarged scale a part of the focusing system shown in FIG. 1.
- the sleeve 4 is made of ferromagnetic material and forms a shunt for the magnets 5 and pole pieces 6.
- a variation of less than 1% in the amplitudes of the alternating field was observed, with the temperature rising from 20 to C.
- a focusing system as claimed in claim 1, wherein the magnetic material of said further cylindrical sleeve comprises 25 to 35% of nickel and 75 to 65 of iron.
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
- Particle Accelerators (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Description
April '28, 1970 R. E. JOANNAIS ETAL MAGNETIC FOCUSING SYSTEM Filed March 7, 1968 ilirlrlllllillfllilli United States Patent 3,509,504 MAGNETIC FUCUSING SYSTEM Roger E. .loannais and Raymond Defain, Paris, France, assignors to CSF-Compagnie Generale de Telegraphic Sans Fil, a corporation of France Filed Mar. 7, 1968, Ser. No. 711,448 Claims priority, application; France, Mar. 14, 1967, 98 6 4 Int. Cl. 1 1011 3/12 US. Cl. 335211 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to magnetic focusing systems of the kind used for beam concentration purposes in O-type travelling wave tubes.
It is Well known that in magnetic focusing devices, the useful magnetic field is the stronger the higher the coercive force of the magnets. For this reason, ferrites having a coercive force (H :3000 oersteds) higher than that of other magnetic materials, are generally used. Unfortunately, the magnetic properties of ferrites are highly sensitive to temperature variations. The temperature coefiicient of ferrites is in the order of 0.2% per degree centigrade and a temperature variation of 80 C. produces a field loss of about 16%. Yet, for proper operation of tubes using periodic permanent magnet devices, as in travelling wave tubes, it is essential that the focusing field should be as stable as possible.
This problem has already been overcome in a variety of ways, each, however, giving rise to a relatively complicated structure.
It is an object of this invention to provide a focusing system, which avoids such drawbacks.
According to the invention, there is provided a magnetic focusing system comprising annular ferrite pieces having polarities alternating from one piece to the next, spaced by pole pieces and forming a cylindrical sleeve; and a further cylindrical sleeve of magnetic material positioned within said first mentioned sleeve for shunting said pole pieces, said further sleeve being arranged for receiving that portion of a travelling wave tube through which a delay line extends.
For a better understanding of the invention and to show how the same may be carried into effect, reference will be made to the drawing accompanying the following description and in which:
FIG. 1 illustrates a travelling wave tube employing a magnetic focusing system according to the invention;
FIG. 2 illustrates the focusing system on an enlarged scale; and
FIG. 3 i an explanatory graph.
In FIG. 1, a travelling wave tube 1 has been illustrated, comprising an electron-gun 2 near one end and a helical delay line 3 between the gun and the other end of the tube where the collector 7 is located.
The part of the tube containing the helical line 3 is located within a magnetic focusing system which comprises a cylindrical sleeve 4 placed within another sleeve formed of annular ferrlte magnets 5, magnetized in the direction parallel to the tube axis, whose polarities are 3,509,504 Patented Apr. 28, 1970 alternately inverted so that they are NS, SN, NS, SN etc., and between which annular pole pieces 6 with a T shaped section are inserted.
FIG. 2 illustrates on an enlarged scale a part of the focusing system shown in FIG. 1.
In accordance with the invention, the sleeve 4 is made of a ferromagnetic material, for example of 25 to 35% of nickel and to 65% of iron, whose induction varies rapidly as a function of temperature. The magnetic properties of a material of this sort are illustrated in the graph of FIG. 3, in which the temperature in degrees centigrade is plotted along the abscissa and the saturation flux B in kilogauss along the ordinates.
The sleeve 4 is made of ferromagnetic material and forms a shunt for the magnets 5 and pole pieces 6.
In operation, any increase in temperature of the system results in a simultaneous reduction of the induction in the magnets 5 and in the magnetic sleeve 4. Consequently, the field produced by the magnets 5 reduces, but the shunt effect created by the sleeve reduces too, since its induction at saturation drops 0E. The proportion of the mag netic flux taken by the sleeve is therefore less than before the temperature rise.
For proper operation, the two effects should balance one another and the useful flux remain therefore substantially unchanged and the amplitudes of the alternating field along the axis of the focusing system remain substantially constant. In other words, temperature effects are compensated.
In one embodiment of the invention, a variation of less than 1% in the amplitudes of the alternating field was observed, with the temperature rising from 20 to C.
Of course the invention is not limited to the embodiment described and shown which was given solely by way of example.
What is claimed is:
1. A magnetic focusing system comprisingzannular ferrite pieces having polarities alternating from one piece to the next, pole pieces spacing said annular pieces and forming a cylindrical sleeve; and a further cylindrical sleeve of a magnetic material, whose induction is temperature dependent, positioned within said first mentioned sleeve for shunting said pole pieces for achieving a magnetic field compensating effect extending through the whole of said focusing system, said further sleeve being arranged for receiving that portion of a travelling wave tube through which a delay line extends.
2. A focusing system as claimed in claim 1, wherein the magnetic material of said further cylindrical sleeve comprises 25 to 35% of nickel and 75 to 65 of iron.
3. A focusing system as claimed in claim 1, wherein said pole pieces are T shaped, the horizontal bar of said T being positioned between said two sleeves.
4. A travelling wave tube having a focusing system as claimed in claim 1.
References Cited UNITED STATES PATENTS 2,812,469 11/1957 Kleinet a1. 315 3.5 2,843,775 7/1958 Yasuda 313--84 2,867,745 1/1959 Pierce 315 3.5 3,061,754 10/1962 Kajihara 313 s4 3,178,602 4/1965 Meixner 313 84 3,271,616 9/1966 Verger 313-84XR GEORGE HARRIS, Primary Examiner US. Cl. X.R. 315-35; 335-217
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR98694A FR1522411A (en) | 1967-03-14 | 1967-03-14 | Compensation for the effects of temperature in magnetic focusers |
Publications (1)
Publication Number | Publication Date |
---|---|
US3509504A true US3509504A (en) | 1970-04-28 |
Family
ID=8626872
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US711448A Expired - Lifetime US3509504A (en) | 1967-03-14 | 1968-03-07 | Magnetic focusing system |
Country Status (5)
Country | Link |
---|---|
US (1) | US3509504A (en) |
DE (1) | DE1616401A1 (en) |
FR (1) | FR1522411A (en) |
GB (1) | GB1192484A (en) |
NL (1) | NL6803518A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3755706A (en) * | 1972-03-20 | 1973-08-28 | Varian Associates | Miniaturized traveling wave tube |
CN106756601A (en) * | 2016-12-01 | 2017-05-31 | 重庆材料研究院有限公司 | A kind of temperature range wide, the magnetic temperature compensating alloy of high linearity |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2812469A (en) * | 1952-04-08 | 1957-11-05 | Int Standard Electric Corp | Travelling wave tube arrangement |
US2843775A (en) * | 1955-06-28 | 1958-07-15 | Int Standard Electric Corp | Electron tube magnetic focusing device |
US2867745A (en) * | 1953-10-07 | 1959-01-06 | Bell Telephone Labor Inc | Periodic magnetic focusing system |
US3061754A (en) * | 1960-03-18 | 1962-10-30 | Gen Precision Inc | Temperature compensating element for a traveling wave tube periodic array |
US3178602A (en) * | 1960-12-30 | 1965-04-13 | Gen Precision Inc | Adjustable permanent magnet focusing array |
US3271616A (en) * | 1961-04-04 | 1966-09-06 | Csf | Focusing systems with alternating magnets for traveling wave tubes |
-
1967
- 1967-03-14 FR FR98694A patent/FR1522411A/en not_active Expired
-
1968
- 1968-03-07 US US711448A patent/US3509504A/en not_active Expired - Lifetime
- 1968-03-11 GB GB01851/68A patent/GB1192484A/en not_active Expired
- 1968-03-12 NL NL6803518A patent/NL6803518A/xx unknown
- 1968-03-13 DE DE19681616401 patent/DE1616401A1/en active Pending
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2812469A (en) * | 1952-04-08 | 1957-11-05 | Int Standard Electric Corp | Travelling wave tube arrangement |
US2867745A (en) * | 1953-10-07 | 1959-01-06 | Bell Telephone Labor Inc | Periodic magnetic focusing system |
US2843775A (en) * | 1955-06-28 | 1958-07-15 | Int Standard Electric Corp | Electron tube magnetic focusing device |
US3061754A (en) * | 1960-03-18 | 1962-10-30 | Gen Precision Inc | Temperature compensating element for a traveling wave tube periodic array |
US3178602A (en) * | 1960-12-30 | 1965-04-13 | Gen Precision Inc | Adjustable permanent magnet focusing array |
US3271616A (en) * | 1961-04-04 | 1966-09-06 | Csf | Focusing systems with alternating magnets for traveling wave tubes |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3755706A (en) * | 1972-03-20 | 1973-08-28 | Varian Associates | Miniaturized traveling wave tube |
CN106756601A (en) * | 2016-12-01 | 2017-05-31 | 重庆材料研究院有限公司 | A kind of temperature range wide, the magnetic temperature compensating alloy of high linearity |
CN106756601B (en) * | 2016-12-01 | 2018-10-26 | 重庆材料研究院有限公司 | It is a kind of width temperature range, high linearity magnetic temperature compensating alloy |
Also Published As
Publication number | Publication date |
---|---|
DE1616401A1 (en) | 1971-04-15 |
FR1522411A (en) | 1968-04-26 |
NL6803518A (en) | 1968-09-16 |
GB1192484A (en) | 1970-05-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3205415A (en) | Permanent magnet device | |
US2503173A (en) | Permanent magnetic electron lens system | |
US5014028A (en) | Triangular section permanent magnetic structure | |
US2918593A (en) | Traveling wave tubes | |
US2867745A (en) | Periodic magnetic focusing system | |
US2911554A (en) | Non-reciprocal wave transmission device | |
US2797360A (en) | Travelling wave amplifiers | |
US2843775A (en) | Electron tube magnetic focusing device | |
US2871395A (en) | Magnetic structures for traveling wave tubes | |
GB1030148A (en) | High power electron tube apparatus | |
US2936408A (en) | Permanent magnets | |
US3509504A (en) | Magnetic focusing system | |
US2867744A (en) | Traveling wave tube | |
GB945610A (en) | Velocity modulated discharge devices with magnetic beam focusing | |
USRE33736E (en) | Periodic permanent magnet structure with increased useful field | |
GB865725A (en) | Improvements in or relating to magnetic focusing systems for travelling-wave tubes | |
US3178602A (en) | Adjustable permanent magnet focusing array | |
US2925517A (en) | Electron beam focusing magnetic circuit | |
US3259788A (en) | Magnetic focussing device for an electron tube | |
US3183398A (en) | Beam focusing magnet | |
US3239712A (en) | Linear accelerator slow wave structure | |
US3020440A (en) | Electron beam device | |
GB834958A (en) | Improvements in or relating to magnetic focusing systems for travelling wave tubes | |
US3375400A (en) | Radial magnet beam focusing system | |
US3373388A (en) | Permanent magnet system for the generation of at least two opposite magnetic fields lying one behind the other for the bundled guidance of an electron beam, especially for traveling wave tubes |