US2408238A

US2408238A - Space discharge device

Info

Publication number: US2408238A
Application number: US490113A
Authority: US
Inventors: Percy L Spencer
Original assignee: Raytheon Manufacturing Co
Current assignee: Raytheon Co
Priority date: 1943-06-07
Filing date: 1943-06-07
Publication date: 1946-09-24
Anticipated expiration: 1963-09-24

Description

P. L. SPENCER SPACE DISCHARGE DEVICE Sept. 24, 1946.

Filed June 7, 1945 2 Sheets-Sheet 1 r L. SPENCER SPACE DIS CHARGE DEVICE se a 24, 1946.

Filed June 7, 1945 2 Sheets-Sheet 2 imam-0 PERCY Patented Sept. 24, 1946 SPACE DISCHARGE DEVICE Percy L. Spencer, West Newton, Mass, assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application June 7, 1943, Serial No. 490,113

This invention relates to a magnetron, and more particularly to a magnetron in which the dimensions of the internal Structure determine the frequency of the oscillations produced.

In magnetrons of this kind it is often difiicult to construct the component parts thereof within sufficiently accurate limits which will produce a desired frequency within narrow limits,.particularly when the oscillations generated are of extremely short wave lengths of the order of centimeters. Therefore it is desirable that some arrangement be devised for adjusting the magnetron after it has been completed to bring its frequency of oscillation to an exact predetermined value, even though in the initial form of the magnetron said frequency may deviate somewhat from'said predetermined value.

An object of this invention is to devise a magmatron of the foregoing type in which simple but efieotive adjusting or tuning means are provided. Another object is to accomplish the foregoing 7 Claims. (Cl. 250-275) with substantially no increase in the complexity of the tube structure so as to make the tube completely interchangeable with those forms which do not contain such an adjusting or tuning arrangement.

The foregoing and other objects of this invention will be best understood from the following description of an exemplification thereof, reference being had to the accompanying drawings, wherein:

Fig. 1 is a vertical section through a magnetron incorporating my invention;

- Fig. 2 is a cross-section taken approximately along line 2-2 of Fig. 1, with certain parts there-' of broken away; and

' Fig. 3 is an enlarged section of a detail of the supporting structure at the top of the cathode shown in Fig. l.

The magnetron illustrated in the drawings comprisesa tubular envelope I made of a cylinder of conducting material, such as copper. The ends of the envelope are covered by caps 2 and 3 likewise formed of conducting material, such as copper, and hermetically soldered in place on the ends of the envelope I. The envelope I is formed with a central annular projection 4. A plurality of radial plates 5 are soldered in place along the inner surface of the projection 4. These plates may be stamped out of a sheet of highly-conductive copper. The inner ends of the plates 5 form anode faces which cooperate with a cathode 6 supported substantially centrally of said anode faces. The cathode 6 is preferably of the indirectly-heated oxide-coated thermionic type having an outer conducting cylinde coated'with electron emissive' oxides and having.

an internal heater, the end conductors I and 8 of which project from the opposite ends of the One of the conductors B cathode structure 5. may be electrically connected to the external cathode sleeve, while the end conductor I isinsulated from said sleeve. Light conducting shields 9 and I0 may be supported adjacent the upper and lower ends of the cathode 6 so as to prevent electron beams from being projected out toward the end caps 2 and 3. The cathode 6. is supported by a cathodeand heater lead-inconductor II Welded to the end conductor 8, which as described above is electrically connected to the cathode and to one end of the cathode heater. The lead-in conductorI I is sealed through 'a glass seal I2 mounted at the outer end of a conducting pipe I3 hermetically fastened through the wall of the envelope I adjacent the lower end thereof. A

second lead-in conductor I 4 is sealed through a;

similar glass seal I5 mounted at the outer end: of a conducting pipe I6 likewise hermetically sealed through the wall of the envelope I at the'upper end thereof. The inner end of the lead-in con-1 ductor I 4 carries a connecting rod H, the outer,

end of which in turn carries a split sleeve I8: As shown in Fig. 3, the split sleeve I8 surrounds the end conductor 1 snugly so as to afford a'supporting and steadying action-to the upper end of the cathode structure. However, the engagement be the en'd'conductor l, a flexible electrical connect-' er I9 has one end thereof welded to the end conductor I and the other end thereof welded to the rod I'I.

When such a magnetron is placed between suitable

magnetic poles

20 and 2| to create a longitudinal magnetic field and the device is energized, oscillations are set up. These oscillations may be lead out from the tube my means of a coupling loop 22 extending into the space between two of the plates 5; One end of the coupling loop 22 is connected to the inner end of a conducting pipe 2" hermetically sealed through the wall of the envelope I substantially midwaybetween the ends thereof; The otherend of the coupling loop 7 22' is connected to a conductor 24 which passes through said pipe 23 and is sealed through a glass 23 is broken away at its central portion, but it is understood that said pipe may be substantially of the same length as the pipes l3 and [6 of Fig. 1. An additional conducting pipe, not shown, may be electrically connected to the pipe 23 and form with the conductor 24 a concentric line through which the high frequency oscillations generated? by.:- the wmagnetron maybe: conducted: to a suitable utilization circuit.

Each pair of anode arms together with the portion of the projection 4 between them form an oscillating cavity. A capacitance exists be-. tween the cathode B and the end faces of the anode arms 5. Also capacitancesexist between the side walls of each oscillating cavity. The

conductive path around each cavity afforded by the side walls thereof constitutes an induct,anc e.,

The anode, therefore, is so designed andspaced relative to the cathode that the inductances andcapacitances described constitute tuned circuits. I-t-i-s desired that thesecircuits Shall be resonant at 'a definite predetermined frequency at which the: device is to be operated. The device is in? tended to operateso that each oscillating cavity is tuned to the frequency at which each of the other oscillating cavities. oscillate.

It is often difiicult to predetermine th'e dimensions ofthe structure so as to cause the anode structure to oscillate at exactly the desired predeterminedfrequency; However, means maybe provided wherebythe normal frequency of oscillation of the magnetron can be adjusted over a fairly wide range even after the magnetron has been completed. For example, I have described and claimed a tuning arrangement in my copending application, Serial No. 425,071, filed December 31 1941. In accordance with my present invention, this type of tuning is utilized in an arrangement which is of simplified but nevertheless efiective construction. In order to produce such tuning, a light flat metal rin 26. is held in juxtaposed position adjacent the inner ends of the anode arms; 5. The ring 26 is supported by the innor end of the rod 142' by meansof a connecting member 21' welded to the ring26 and to the leadin conductor M. In order to adjust the position of the ring 25,the pipe l8 may be bent slightly. It. will be noted that the lead-in conductor I4 is supported by the seal I5 at a point considerably removed from the position at which the ring 26 is connected to said lead-in conductor. Therefore, a slight. bending ofthe pipe 16: will produce a relatively large movement of the ring 26*. Such bending: of the pipe l6 gives a permanent set thereto, and fixes the position of' the ring 26 in its-proper relation with respect to the anode arms 5 so asto result in the desired tuned condition of the magnetron structure. As already pointed out, during this movementof' the lead-in conductor M, the split sleeve I 3 slides on the end conductor 1 and in the final position of adjustment forms: a support for the upper end of the 'catrhode tructure so that in conjunction with the-support afiorded by the lead-in conductor I I, the; cat-node structure is rigidly and accuratelysupported in place.

Itwill' be noted that the adjustment or tuning described above is in the nature of a factory adjustment to be made at the time that the magnetron is completed in the factory. It will further be noted that when the tube is completed, it is identical, in; so far as; outside appearance and dimensions are concerned with tubes which do not have such a tuningadjustment. Therefore, be m de in a cordance wi h my invention are completely interchangeable with such other tubes. However, by incorporating my invention in the structure, a sufiicient degree of tuning is afiorded, so that those tubes, which otherwise might deviate from the desired frequency to such an extent as to make them commercially unacceptable, are readily brought into the properrange, thus. greatly reducing the percentage of discarded tubes which otherwise might exist.

In accordance with my present understanding of the operation of the invention, varying the position of the conducting ring 26 will vary the capacitances-of' the anode structure as described Y above, without afiecting the inductances thereof to the same degree.

' pacitanoes will tune the natural frequency of the Therefore, varying said camagnetron in the desired manner.

Of course it is to be understood that this invention is not limited to the particular detailsas described above as many equivalents will su gest themselves to those skilled in the art. For example, the conducting surface which is moved adjacent elements of the anode structure mightbe disposed adjacent. other portions of said anode structure. Likewise. elements which Vary the inductance of the oscillating portions of the anode structure might be supported and adjusted in accordance with the principles of my invention.

What is claimed is:

1. An. electron discharge device comprising an envelope containing-a cathode and an anode, said anode having a plurality of electron-receiving l portions adjacent said cathode, and a cavity resonator interconnecting each pair of electron-receiving portions, said cathode having a pair of electrical terminals, said cathode being rigidly supported within said envelope and provided with an external electrical connection for one of its terminals, a lead-in conductor for the other of said terminals sealed through the wall of said envelope, a flexible electrical conductor connecting said. lead-in conductor with the other of said terminals, and a tuning member for said cavity resonator carried by said lead-in conductor, the connection between said lead-in conductor and the wall of said envelope being sufficiently adjustable to provide an adjusting movement of said lead-in conductor and the tuning member carried thereby.

2. Anelectron discharge. device, comprising an envelope containing a cathode and an anode, said anode having a plurality of electron-receiving portions adjacent. said cathode, and a plurality of cavity resonators interconnecting pairs of electronrreceiving portions, said cathode having a pair of electrical terminals, said cathode being rigidly supported within said envelope and provided with an external electrical connection for one of; its-terminals, a lead-in conductor for the other of said terminals sealed through the wall of said envelope-, a flexible electrical conductor connecting-said lead-in conductor with the other of saidterrninals, and a tuning member for said cavity resonators carried: by said lead-in conductor, the connection between said lead-in cone ductor and the wall of said envelope being sufiicientlyadjustable to provide an adjusting movement of said lead-in conductor and'the tuning member carried thereby.

3. *An electron discharge device comprising an envelope containing" a cathode and an anode, said po ons djacen said thode, nda cavi yresoe nator interconnecting each pair of electron-receiving portions, said cathode having a pair of electrical terminals, a pair of lead-in conductors for said cathode sealed through the Wall of said envelope, said cathode being supported by one of said lead-in conductors rigidly connected to one end of said cathode and electrically connected to one of said terminals, the other of said lead-in conductors being connected to the other of said cathode terminals by a flexible connection, and a tuning member for said cavity resonator carried by said last-named lead-in conductor, the connection between said last-named lead-in conductor and the wall of said envelope being sufficiently adjustable'to provide an adjusting movement of said lead-in conductor and the tuning member carried thereby.

4. An electron discharge device comprising an envelope containing a cathode and an anode, said anode having a plurality of electron-receiving portions adjacent said cathode, and a cavity resonator interconnecting each pair of electronreceiving portions, said cathode having a pair of electrical terminals, a pair of lead-in conductors for said cathode sealed through the wall of said envelope, said cathode being supported by one of said lead-in conductors rigidly connected to one end of said cathode and electrically connected to one of said terminals, the other of said lead-in conductors being connected to the other of said cathode terminals by a flexible connection, and a tuning member for said cavity resonator carried by said last-named lead-in conductor, the connection between said last-named lead-in conductor and the wall of said envelope being surficiently adjustable to provide an adjusting movement of said lead-in conductor and the tuning member carried thereby, said last-named leadin conductor having a member in sliding engagement with a portion of said cathode forassisting in the support of said cathode in the adjusted position of said last-named lead-in conductor.

5. An electron discharge device comprising an envelope containing a cathode and an anode, said anode having a plurality of electron-receiving portions adjacent said cathode, and a cavity resonator interconnecting each pair of electronreceiving portions, said cathode having a pair of electrical terminals, said cathode being rigidly supported within said envelope and provided with an external electrical connection for one of its terminals, a lead-in conductor for the other of said terminals, said lead-in conductor extending tension being capable of being bent into predetermined set positions to provide an adjusting movement of said lead-in conductor and the tuning member carried thereby.

6. A magnetron comprising an envelope con-' taining a cathode and an anode, means for producing a magnetic field about said cathode, said anode having a plurality of electron-receiving portions adjacent said cathode, and a cavity resonator interconnecting each pair of electronreceiving portions, said cathode having a pair of electrical terminals, said cathod being rigidly supported within said envelope and provided with an external electrical connection for one of its terminals, a lead-in conductor for the other of said terminals sealed through the wall of said envelope, at flexible electrical conductor connecting said lead-in conductor with the other of said terminals, and a tuning member for said cavity resonator carried by said lead-in conductor, the connection between said lead-in conductor and the wall of said envelope being suificiently adjustable to provide an adjusting movement of said lead-in conductor and the tuning member carried thereby, I

7. A magnetron comprising an envelope containing a cathode and an anode, said anode having a plurality of electron-receiving portions adjacent said c athode, and a cavity resonator interconnecting each pair of electron-receiving portions, saidcathode having a pair of electrical ter-' minals, said cathode being rigidly supported within said envelope and provided with an external electrical connection for one of its terminals, a lead-in conductor for the other of said terminals, saidlead-in conductor extending through a seal mounted at the outer end of a tubular extension mounted on said envelope, a flexible electrical conductor connecting said lead-in conductor with-the other of said terminals, and a tuning member for said cavity resonator carried by said lead-in conductor, said tubular extension being capable of being bent into predetermined set positions to provide an adjusting movement of said lead-in conductor and the tuning member carried thereby.

. PERCY L. SPENCER.