US2445447A

US2445447A - Electron discharge device utilizing cavity resonators

Info

Publication number: US2445447A
Application number: US474912A
Authority: US
Inventors: Jr Stuart T Martin
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1943-02-06
Filing date: 1943-02-06
Publication date: 1948-07-20
Anticipated expiration: 1965-07-20
Also published as: GB603570A

Description

July 20, 1948. s. T. MARTIN, JR 2,445,447

ELECTRON DISCHARGE ICE UTILIZING CAVITY RESO CR5 2 Sheets-Sheet 1 Filed Feb. 6, 1945 ISmaentor (Ittorneg July 20, 1948. s. r. MARTIN, JR 2,445,447

ELECTRON DISCHARGE DEVICE UTILIZING I I CAVITY RESONATORS Filed Feb. 6, 194:5 2 Sheets-Sheet 2 ZSnnentor attorney patented July 20, 1948 UNITED STATES PATENT OFFICE ELECTRON DISCHARGE DEVICE UTILIZING CAVITY RESONATOR-S of Delaware Application February 6, 1943, Serial No. 474,912

9 Claims. 1

My invention relates to electron discharge devices useful at ultra high frequencies, more particularly to such devices of the magnetron type. 1

In one form of magnetron particularlyuseful at ultra high frequencies, an elongated cathode is surrounded by a cylindrical block of conducting material, for example copper, having an opening extending longitudinally therethrough to form a .cylindrical chamber coaxial with the cathode. symmetrically spaced around the cylindrical chamber and extending longitudinally of the solid conducting block and parallel to the chamber are a plurality of cylindrical cavities connected with the central chamber by means of radial slots. The result is a plurality of anode segments connected by means of what are in effect resonant cavity circuits. Cupshaped depressions are formed in the top and bottom ends of the block and the ends of the block are closed and sealed with conducting discs. The cathode leads and coupling loop are properly sealed in the block tooprovide a vacuum-tight interior. Cooling fins are secured-to the outside of the block. There is thus provided in effect a closed conducting envelopefor the magnetron.

In tubes of this type aproblem is presented in connection with the gettering of the tube. Conventional high frequency flashing of the getter is not possible due to shielding of the metal envelope. Either an extra lead must be provided in the anode block or a bulb containing the getter must be attached to one of the cathode leadcap seals. In the first case the extra lead makes the attachment of the cooling fins more complex and in the second case the position of the getter bulb greatly increases the hazards of destruction of the tube during handling and installation.

An object of my invention is to provide an electron discharge device of the magnetron type with an improved means of gettering the tube.

More specifically an object of my invention is to provide such a device which is completely enclosed by a metal envelopebut in which the getter may be flashed without the use of external leads for the getter, or the use of an extra getter bulb.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best beunderstood by reference to the following description taken inconnection with the accompanying drawing in which Figure 1 is a top plan view with cover removed of an electron discharge device-made according to myiinvention, Figure 2 is a side view with parts broken away to show details of construction, Figure 3 is a plan view with cover'removed of a modification of an electron discharge device made according to my invention, Figures 4 and 5 are partial perspectives showing details of construction of the getter arrangements used in the electron discharge devices shownin Figures 1 to 3 inclusive and made according to my invention.

In Figure 1 an electron discharge device of the magnetron type comprises an indirectly heated cathode it supported by lead and support wires ll. Surrounding and coaxial with the cathode is a cylindrical anode block I2 of conducting material, for example of copper, and provided at its center with a cylindrical chamber I3 co: axial with and surrounding the cathode. Symmetrically spaced around this cylindrical chamber l3 are a plurality of small cylindrical cavities l4, coextensive with chamber I3. The cavities are connected to the cylindrical chamber [3 by means of radial slots [5, thus providing a plurality of anode segments between adjacent pairs of slots. The chambers [4 provide in effect resonant cavity circuits connected between adjacent anode segments. Thes cavity circuits are excited during operation so that an electromagnetic field is generated within the cavity, the cavities being coupled with each other by these fields. The anode block I2 is provided at its ends with cupshaped depressions I6 and 11 into which the ends of the cathode I0 extend. The ends of the anode block are closed by conducting discs l8 and I9 sealed with a vacuum-tight seal to the block. Cooling fins 20 are secured to the outside of the anode block.

The cathode leads and supports l l are provided with extensions 22 extending through passageways (not shown) and the tubular members 23 coaxial with leads 22. A vacuum-tight seal is provided by means of the elongated cup-shaped sealing members 23.. If desired, coaxial line cables may be connected to these cathode leads for tuning the same to prevent high frequency losses in the cathode leads. A coupling loop 2,4 is mounted within one of the resonant cavities, is provided with a lead 25 extending through a passageway (not shown), and is surrounded by a coaxial threaded member 21 and a cup-shaped sealing member of insulating material 26. This coupling loop may be connected to a coaxialline cable, the outer line being secured to threaded member 21 and the inner conductor to the lead 25.

In accordance with my invention I position a getter loop 30 between a pair of resonant cavities and connect its ends near the tip of an anode segment and to the wall of the cup-shaped depression. As shown in Figure 4 this loop 30 is of U-shaped transverse section and has within it a getter material 3| of any well known kind. The ends of the loop may be welded at points 32 and 33. In operation an R. F. field of sufiicient intensity is generated which in extending between pairs of adjacent cavities induces a high radio frequency current in loop 39, heating the same to flash the getter. of the magnetic field may be increased to burn the loop out so that it will not thereafter affect the tubes operation.

A modification of my invention is shown in Figure 3. Like numbers designate like elements as in Figure 1.

In this modification the getter loop 35 takes the form of a closed ring as shown in Figures 3 and 5. This also may have a U-shaped transverse section and be filled with getter material 36. An arm 31 welded to the wall of the anode block positions and supports the ring above the end of and coaxial with one of the resonant cavities. The getter may be flashed and the ring burned out in a manner similar to that shown in the modification shown in Figures 1 to 3, inclusive, by the linkage of the field generated within the cavity and extending between cavities.

Thus with my invention, the necessity for external connections for the getter is eliminated, the tube construction is simplified and the hazards of breakage in handling and installation are materially decreased.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having a cathode for supplying electrons, an anode member of solid conducting material having a chamber centrally thereof into which electrons are directed, said anode member having a plurality of cavities positioned around the central chamber and coextensive therewith and having slots connecting said cavities with said central chamber to provide anode segments between said slots, and a getter loop adjacent one end of said anode member and positioned to be in the radio frequency field extending between the ends of said cavities for. flashing the getter when said device is excited.

2. An electron discharge device having a cathode for supplying electrons, an anode member of solid conducting material having a centrally positioned chamber into which electrons are directed from said cathode, said :anode member having a plurality of cylindrically shaped cavities positioned around said centrally positioned chamber and coextensive therewith and having slots connecting said cavities with said centrally positioned chamber to provide anode segments between said slots, and a getter loop adjacent one end of said anode member and positioned to be in the radio frequency field extending between the After flashing the intensity- .ends of said cavities for flashing the getter when said device is excited, and means for providing a magnetic field longitudinally of said centrally positioned chamber.

3. An electron discharge device having an elongated cathode, an anode block of cylindrical shape surrounding said cathode and provided with a central cylindrical chamber extending longitudinally of said anode block, and having a plurality of cylindrically shaped cavities extending longitudinally of and parallel to said chamber, said block having radial slots connecting said cavities with the central chamber to provide anode segments between said slots and cavity resonators between said segments, a getter loop positioned between adjacent cylindrically shaped cavity resonators and having one end connected near the edge of an anode segment and its other end connected to the wall of the anode block, said getter loop being positioned to be in the radio frequency field extending between the ends Of said cavity resonators for flashing the getter when said device is excited.

4. An electron discharge device having an elongated cathode, an anode block of cylindrical shape surrounding said cathode and provided with a central cylindrical chamber extending longitudinally of said anode block, said anode block having a plurality of cylindrically shaped cavities extending longitudinally of and parallel to said central chamber, said block having radial slots connecting said cavities with the central cylindrical chamber to provide anode segments between said slots and cavity resonators between said segments, one end of said anode block being provided-with a cup-shaped depression and a getter loop within said cupshaped depression and positioned to be in the radio frequency field extending between the ends of said cavities for flashing the getter when the device is excited and a conducting plate member closing said cup-shaped depression.

5. An electron discharge device having an elongated cathode, an anode block of cylindrical shape surrounding said cathode and provided with a central cylindrical chamber extending longitudinally of said anode block, said block having a plurality of cylindrically shaped cavities extending longitudinally of and parallel to said central chamber, said block having radial slots connecting said cavities with the central cylindrical chamber to provide anode segments between said slots and cavity resonators between said segments, the ends of said anode block being provided with cup-shaped depressions and a getter loop positioned within one of said depressions, anda pair. of' conducting plate members closing said cup-shaped depressions, said getter loop being closed and extending from the wall of the cup-shaped depression and coaxial with one of said cavities.

6. An electron discharge device having a cathode for supplying electrons, a plurality of anode segments defining a space into which said electrons are directed, conducting members connecting adjacent segments and providing cavity resonators therebetween, and a getter loop adjacent one end of said anode segments and positioned to be in the radio frequency field extending between the ends of said cavity resonators for fiashing said getter when said device is excited.

7. An electron discharge device having an elongated cathode for supplying electrons and a plurality of anode segments surrounding said cathode, and conducting means connected between adjacent segments for providing cavity resonators between said segments, and other metallic means closing the ends of said cavity resonators and enclosing said cathode, and a getter loop adjacent one end of said anode segments and positioned within said metallic closing means and positioned to be in the radio frequency field extending between the ends of said cavity resonators for flashing the getter when said electron discharge device is excited.

8. An electron discharge device having a cathode for supplying electrons, an anode block of cylindrical shape surrounding a space into which electrons are directed from said cathode and provided with a central cylindrical chamber extending longitudinally of said anode block, and having, a plurality of cylindrically shaped cavities extending longitudinally of and parallel to said chamber, said block having radial slots connecting said cavities with the central cylindrical chamber to provide anode segments between said slots and cavity resonators between said segments, a getter loop comprising a ring positioned adjacent one end of said block and coaxial with one of said cylindrically shaped cavities, said ring being secured to the wall of the anode block, said getter loop being positioned to be in the radio frequency field extending between the ends of said cavity resonators for flashing the getter when said device is excited.

9. An electron discharge device having an elongated cathode and an anode block of cylindrical shape surrounding said cathode and provided with a central cylindrical chamber extending longitudinally of said anode block, said block having a plurality of cavities extending 6 longitudinally of and parallel to said chamber, said block having slots connecting said cavities with said central cylindrical chamber to provide anode segments between said slots and cavity resonators between said segments, the ends of said anode block being provided with cup-shaped depressions and a getter loop positioned within one of said depressions, and conducting plate members closing the ends of said 10 anode block, said getter loop comprising a ring supported in a plane transverse to the longitudinal axis of a resonator, said ring being coaxial with a resonator, said getter loop being positioned to be in the radio frequency field extending between the ends of said cavity resonators for flashing the getter when said device is excited.

STUART T. MARTIN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,638,551 Rionci Aug. 9, 1927 2,063,342 Samuel Dec. 8, 1936 2,226,653 Allerding et al. Dec. 31, 1940 2,247,077 Blewett et al. June 24, 1941 2,252,118 Dallenbach et al. Aug. 12, 1941 2,394,396 Mouromtseff et al. Feb. 5, 1946 2,408,234 Spencer Sept. 24, 1946 2,412,302 Spencer Dec. 10, 1946 5 FOREIGN PATENTS 7 Number Country Date 215,660 Switzerland Oct. 16, 1941 509,102 Great Britain July 11, 1939