US 2413309 A
Description (OCR text may contain errors)
Dec. 31, 1946'. BENIOFF ELECTRICAL APPARATUS Original Filed June 24, 1941 2 SheetsSheet l 194$- H. BENIOFF 2,413,309
ELECTRICAL APPARATUS Original Filed June 24, 1941 2 Sheets-Sheet 2 Patented Dec. 31, 1946 ELECTRICAL APPARATUS Hugo Beniofi, La Canada, Calif., assignor, by mesne assignments, to Submarine Signal Company, Boston, Mass, a corporation of Delaware Original application June 24, 1941, Serial No. 399,495. Divided and this application February 20, 1942, Serial No. 431,685
The present invention is a division of my copending application Serial No. 399,495, filed June 24, 1941.
The present invention relates to thermionic magnetron tubes of the type in which the tube element forms part of an oscillating circuit and is adaptable for use at extremely high radio frequencies in the range of 300 megacycles and higher, especially for high power. The invention herein described relates to that type of thermionic magnetron tube in which the tube elements themselves form parts of a resonant circuit. In particular, the anode is in the form of a cavity resonator of a toroidal shape having a concentric slot forming the mouth of the resonator. The cylindrical cathode is coaxial With the anode and mounted in relationship with the anode slot as will be more fully understood in the specification below. The cooperating constant magnetic field is adjusted to such a value as to make the electron orbital frequency substantially equal to the resonant frequency of the anode cavity resonator. The direction of the magnetic field so created may be either parallel to the toroidal axis of revolution or parallel to the circular toroidal axis of revolution or even perpendicular to the toroidal axis of revolution. In these cases the electric field will be arranged perpendicular to the magnetic field and the resultant plane of the electron orbital frequency will be perpendicular to the magnetic field.
The thermionic magnetron tube of the present type readily lends itself to constructions using a group of resonators which can be stacked axially to form multiple resonator systems.
The invention will be more fully described in the specification below which is to be read in connection with the drawings illustrating the invention in which Fig. 1 shows a vertical section through the center of the tube; Fig. 2 shows a vertical section of the modification shown in Fig. 1 in which a lurality of resonators are employed, the section being in relatively the same position as the section of Fig. 1; Fig. 3 shows a central section through a modified form of the invention shown in Fig. 1; Fig. 4 shows a similar central section through another modified form; Fig. 5 shows a section on the line 5-5 of Fig. 1; and Fig. 6 shows a still further modified form in perspective of the invention shown in Fig. 1;
In the device illustrated in Fig. 1 the envelope 3B is preferably made of metal, cylindrical in form, with two fiat ends 31 and 32 through the center of which pass the cathode heating leads 33 and 34 which are sealed to the end walls 3| 3 Claims. (Cl. 25027.5)
and 32, respectively, by means of insulating glass seals and 36 mounted on the ends of collars 3'! and 38 extending from th flat ends 3! and 32. Within the envelope 30 the leads 33 and 34 extend outward from the central axis into the arms 28 and 29 and support at their vertically extending ends brackets 39 and 40, respectively, by which the cathode 4| is supported. This cathode, as will be seen in Fig. 5, is a ring to which current is conducted by the arms 39 and 40 at opposite ends of a diameter so that two halves of the ring are substantially connected in parallel across the leads 28 and 29. The cathode 4| also supports the top and bottom disc electron shields 21 and 245 by means Of the brackets 25 and 24 extending from the cathode 4| and supporting the electron shield discs 25 and 21 in position above and below the ends of the cathode and overhanging the cathode outwardly in the direction of the anode resonator 42. These shields equalize the field potential about the top and bottom of the hot cathode and prevent electron emission in the direction of the bottom and top covers 31 and 32, respectively.
The anode 42, as indicated in Fig. 1, is in the form of a split hollow toroid with an annular slot 43 extending around the toroid concentric with the cathode 4! and preferably opposite the center. The back wall 44 of the toroid may be the wall of the envelope, the whole structure being substantially symmetrical with the central axis of the toroid. The cavity 45 formed by the wall 44 and the other toroidal walls is spaced, from the end walls 3! and 32 and is placed at a positive potential as against the cathode 4| by means of the anode conductor 46 forming the central conductor of a concentric cable with the external conductor the conducting tube 47. This conductor 48 passes through an insulating glass seal through an opening 48 in the cavity 45 Where it is connected to the wall 44 at 49, thus coupling with the highfrequency cavity circuit oscillating at a resonance determined by the dimensions and operation of the device.
As illustrated in Fig. 1 a magnetizing field is established by the pole 59 which provides a cylindrical pole face over the end of the tube forming a north pole as indicated by the letter N at the to in conjunction with the pole 5! having a similar cylindrical pole face labelled S providing the south pole at the bottom side face of the tube. The envelope or housing is exhausted of air by suitable means after which it may be sealed off a. the pumping connection 52 in the glass seal 35.
In Fig. 2 a. multiple unit is indicated. In this size to those of Fig. 1.
case the metallic housing 53 is made of a longer cylinder as compared with that shown in Fig. 1 but it has approximately the same diameter as that of the device of Fig. 1 with the result that the end cover plates 54 and 55 are similar in However, if desired, the device may be made of a largerdiameter and the spacing of the internal units varied in accordance with the design desired. In Fig. 2 the cylindrical wall 53 supports a plurality of resonating cavities 55, 56, 51, and 58 each of which is provided with annular slots 59, 60, BI and 62, and with individual cathode elements 63, 64, 65, and 66, all parallelly connected across the cathode supply leads Bland 68 which enter through the ends 54 and 55 of the unit in the collars 69 and III which are sealed off with glass seals 'II and I2. Each cathode unit may also be supplied with end shields I3 and I4 as illustrated in Fig, 2. It will sufiice in the construction of Fig. 2 to take the output lead through a single cavity resonator as illustrated by the conductor I5 which passes through a hole I5 in the wall 53 into one of the resonators 55 where it is connected to the inside of the wall as indicated at TI. The metallic tube I8 joined to the cylinder 53 and extending from it forms with the conductor I5 a concentric cable, which concentric cable is continued as in Fig. 1 by means of the conducting tube I9 surrounding the central conductor I5, In Fig. 2 the direct current magnetization field is furnished by the elongated coil 8!] in the center of which the magnetic field runs parallel to the axis of the coil.
In the arrangement shown in Fig. 3 a modified form of cavity resonator is shown. Here the tube assumes a toroidal form with the external walls 8|, 82, 83 and 84 forming the toroid and the cavity resonator as twin chambers 35 and 88 with a restricted conducting passage 87 arranged between the two cavities in the center of which is positioned the cathode ring 88 which is supported by the conductors 89 and 90 passing through the wall 83 and sealed to the wall by means of the glass seals SI and 92 in connection with the extending necks 93 and 94 which may be formed as a part of the walls 83. The cathode heating current is supplied through the leads 89 and 9B and the cathode-anode potential is supplied between the leads 89 or 98 and the conductor 9| which links the anode resonator by passing through the wall of the resonator and being attached to the inner surface of the wall 84 at the point 95. As in the other figures the conductor SI is preferably continued externally of the tube in a concentric cable.
The magnetic field is supplied in the device indicated in Fig. 3 by means of the magnet 91 which has a cylindrical north pole positioned opposite one end of the tube and a cylindrical south pole positioned opposite the other end of the tube. In this case the orbits of the electrons leaving the cathode 88 are maintained substantially in horizontal planes perpendicular to the magnetic field and the resonance of the oscillator is determined by the dimensions and construction of the cavity and the cathode.
In the modification illustrated in Fig. 4 the cavity ID!) has the same geometrical form in crosstakes the form of a flat ring in which the cathode surface is positioned in the plane of the ring. The cathode is supported by means of the current supply leads I04 and I05 passing through the top wall I86 of the resonator through the tubes I01 and I08 and the glass sealing elements I89 and III] as described in connection with the previous figures. The anode lead II2 passes through the tube III into the interior of the resonator I02 and is connected to one of the walls at the inside of the resonator as indicated in the figure. Some latitude is permitted as to the point of connection of the conductor H2. The conductor H2 is brought out of the resonator in a concentric cable as illustrated in Fig. 1. In this arrangement the magnetic flux travels radially from a central north pole core -I I3 to a cylindrical south pole core H4, the core II 3 being placed within the toroidal element and the cylindrical pole H4 being outside of the element so that the lines of flux travel radially in the same plane or in parallel planes to the cathode I03.
In the arrangement shown in Fig. 6 a perspective view of a further construction is illustrated in which the coil 20 surrounds the resonating cavity 22 which has a slot 23 in the inside surface of the resonator wall taking a cylindrical form. The cathode 2i is in the form of a band or ring opposed to the inner wall of the cavity opposite the slot just described. In this construction the magnetic field extends in a direction paralleling the curve of the cathode 2I and the orbitof the electrons from the cathode 2| is in radial planes perpendicular to the cathode.
Having now described my invention, I claim:
1. A thermionic magnetron tube comprising a casing formed as a toroidal shell, means providing a toroidal resonator shell within said toroidal shell and coaxial therewith forming the anode of a magnetron tube, said toroidal resonator shell having a slot coaxial with said resonator shell, a cathode element also coaxial with said resonator shell and positioned in opposed relationship with said resonator shell in the vicinity of the slot in said shell and means forming a magnetizing field extending in a direction perpendicular to the electric field between the cathode and the anode of the magnetron tube.
2. A thermionic magnetron tube comprising a casing formed as a toroidal element, a pair of twin toroidal resonator shells positioned within said toroidal casing, said toroidal resonator shells having means providing wall elements connecting them together in a common mouth extending coaxially with said toroidal resonator shells, a cathode element positioned in said common mouth and having its main surface extending parallel with the walls of the common mouth and means forming a magnetic field extending in a direction perpendicular to the direction of the cathode element.
3. A thermionic magnetron tube having a casing of a toroidal shape, a pair of twin toroidal resonator shells within said casing and having slots therein and cylindrical walls forming a common connecting neck between said resonator shells. the said cylindrical walls being coaxial with the toroidal resonator shells and a cylindrical cathode also coaxial with said resonator shells and said cylindrical walls and means positioning said cylindrical cathode in the common neck between saidresonator shells.