GB2281147A - Magnetic circuit - Google Patents
Magnetic circuit Download PDFInfo
- Publication number
- GB2281147A GB2281147A GB9315117A GB9315117A GB2281147A GB 2281147 A GB2281147 A GB 2281147A GB 9315117 A GB9315117 A GB 9315117A GB 9315117 A GB9315117 A GB 9315117A GB 2281147 A GB2281147 A GB 2281147A
- Authority
- GB
- United Kingdom
- Prior art keywords
- magnetic circuit
- circuit arrangement
- pole pieces
- magnets
- magnetron
- 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.)
- Granted
Links
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
- H01J23/10—Magnet systems for directing or deflecting the discharge along a desired path, e.g. a spiral path
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/02—Permanent magnets [PM]
- H01F7/0205—Magnetic circuits with PM in general
- H01F7/021—Construction of PM
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/02—Permanent magnets [PM]
- H01F7/0273—Magnetic circuits with PM for magnetic field generation
- H01F7/0278—Magnetic circuits with PM for magnetic field generation for generating uniform fields, focusing, deflecting electrically charged particles
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microwave Tubes (AREA)
Abstract
A magnetic circuit arrangement, in particular for use with a magnetron 1, comprises three C-shaped magnets 4, the free ends of which are each attached to a respective sideface 8 of one of a pair of triangular shaped pole pieces 5. Each C-shaped magnet 4 consists of two ferrite blocks 6 joined by an iron strap 7. The pole pieces 5 may each have a circular opening 10. The magnetron 1 is located centrally with respect to the axial magnetic field produced between the triangular pole pieces 5. <IMAGE>
Description
MAGNETIC CIRCUIT
This invention relates to a magnetic circuit, in particular although not exclusively, for use with a magnetron.
Conventionally when producing a magnetron one of the main cost constraints lies in the magnetic circuit. A well known magnetic circuit comprises four generally horseshoe or C-shaped magnets clustered around a pair of axially spaced cube shaped iron pole pieces. Each horseshoe magnet is provided by a pair of rectangular magnetic blocks connected by an iron strap. Surprisingly, we have found that reducing the number of magnets can increase the available magnetic field strength.
It is believed that this is because the size of the iron pole piece can then be reduced and that this reduces the consequential magnetic leakage losses.
Accordingly, this invention provides a magnetic circuit arrangement comprising three C-shaped magnets, the free ends of which are each attached to a respective side face of one of a pair of axially spaced triangular shaped pole pieces.
By employing the invention it is possible to provide a magnetic circuit which not only has improved performance as compared to the above mentioned prior art arrangement, but which is also cheaper to manufacture, lighter and more compact.
In order that the invention may be better understood, an embodiment thereof will now be described with reference to the accompanying diagrammatic drawings, in which;
Figure 1 is a plan view of a magnetic circuit arrangement of the invention; and
Figure 2 is a cross-sectional view along line A-A of Figure 1.
A magnetron 1, shown in dotted outline, is of cylindrical shape having an axis 2. In order to produce an axially extensive magnetic field, indicated by flux lines 3, a magnetic circuit arrangement comprises three generally C-shaped magnets 4 clustered around a pair of axially spaced iron pole pieces 5. Each magnet 4 is formed from a pair of ferrite blocks 6 of rectangular box like shape magnetically connected by an iron
strap 7. The blocks may be formed from another magnetic material such as
Neodinium Boron iron.
According to the invention, the pole pieces 5 are of an equilateral triangle shape when seen in the plan view of Figure 1 and each side face 8 is attached to a
respective free end face 9 of a magnet 4. An axial hole 10 is present in each pole
piece to reduce flux leakage losses.
In an example using identical ferrite magnets it was found that a magnetic field
strength of 4700 Gauss could be produced from an arrangement of the invention as
compared to only 4200 Gauss when four such C-shaped magnets each attached to
a pair of cube shaped pole pieces were used.
It is to be understood that the invention is not limited to the use of a strictly geometrical triangle, for example the corners may be rounded or removed. The straps for the three magnets may be connected to one another as in a sleeve-like arrangement. Alternatively, the magnets may each include an integrally formed strap magnetically connecting the poles.
Claims (6)
1. A magnetic circuit arrangement comprising three C-shaped magnets, the free
ends of which are each attached to a respective sideface of one of a pair of
axially spaced triangular shaped pole pieces.
2. A magnetic circuit arrangement according to claim 1 in which the magnets are
each formed from two blocks of magnetic material connected by a strap.
3. A magnetic circuit arrangement according to Claim 1 or 2 in which the pole
pieces are of an equilateral triangle shape.
4. A magnetic circuit arrangement according to Claim 2 or 3 in which the blocks
of magnetic material are of rectangular box like shape.
5. A magnetic circuit arrangement as claimed in any preceding claim disposed
about a magnetron.
6. A magnetic circuit arrangement substantially as described with reference to the
accompanying drawings.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9315117A GB2281147B (en) | 1993-07-21 | 1993-07-21 | Magnetic circuit |
| JP50501595A JP3300360B2 (en) | 1993-07-21 | 1994-07-21 | Magnetic circuit |
| PCT/GB1994/001579 WO1995003616A1 (en) | 1993-07-21 | 1994-07-21 | Magnetic circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9315117A GB2281147B (en) | 1993-07-21 | 1993-07-21 | Magnetic circuit |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9315117D0 GB9315117D0 (en) | 1993-09-01 |
| GB2281147A true GB2281147A (en) | 1995-02-22 |
| GB2281147B GB2281147B (en) | 1997-01-08 |
Family
ID=10739194
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9315117A Expired - Fee Related GB2281147B (en) | 1993-07-21 | 1993-07-21 | Magnetic circuit |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP3300360B2 (en) |
| GB (1) | GB2281147B (en) |
| WO (1) | WO1995003616A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102421690B1 (en) * | 2017-11-23 | 2022-07-18 | 한국전기연구원 | High Power Magnetron having Magnetic Field Variable Apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB783494A (en) * | 1954-06-11 | 1957-09-25 | Mullard Radio Valve Co Ltd | Improvements in magnetic systems |
| GB2134318A (en) * | 1983-01-22 | 1984-08-08 | English Electric Valve Co Ltd | Magnetrons |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE842817C (en) * | 1950-04-23 | 1952-07-03 | Deutsche Edelstahlwerke Ag | Process for the production of magnets with iron conducting parts |
| US3568115A (en) * | 1967-11-10 | 1971-03-02 | Ca Atomic Energy Ltd | Magnetic material multipole assembly |
| SU693447A1 (en) * | 1978-04-03 | 1979-10-25 | Новочеркасский ордена Трудового Красного Знамени политехнический институт им. Серго Орджоникидзе | Magnetic system |
-
1993
- 1993-07-21 GB GB9315117A patent/GB2281147B/en not_active Expired - Fee Related
-
1994
- 1994-07-21 WO PCT/GB1994/001579 patent/WO1995003616A1/en unknown
- 1994-07-21 JP JP50501595A patent/JP3300360B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB783494A (en) * | 1954-06-11 | 1957-09-25 | Mullard Radio Valve Co Ltd | Improvements in magnetic systems |
| GB2134318A (en) * | 1983-01-22 | 1984-08-08 | English Electric Valve Co Ltd | Magnetrons |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08501906A (en) | 1996-02-27 |
| GB2281147B (en) | 1997-01-08 |
| JP3300360B2 (en) | 2002-07-08 |
| WO1995003616A1 (en) | 1995-02-02 |
| GB9315117D0 (en) | 1993-09-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20120721 |