US 2546976 A
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April 3, 1951 T. H. CLARK ETAL 2,546,976
ELECTRON DISCHARGE'DEVICE AND METHOD OF ASSEMBLY Filed July 21, 1943 2 Sheets-Sheet 1 18 21 714 3 55 v, 60 I I? Y W i 2 50 I 28 29 51 5a u 52 IN VEN TORS April 3, 1951 T. H. CLARK :rm. 2,545,975
ELECTRON DISCHARGE DEVICE AND METHOD OF ASSEMBLY Filed July 21, 1943 2 Sheets-Sheet 2 Patented Apr. 3, 1951 ELECTRON DISCHARGE DEVICE AND METHOD OF ASSEMBLY Trevor H. Clark, New York, N. Y., and Andr Gabriel Clavier and Ernest Rostas, Lyon, France, assignors to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application July 21, 1943, Serial No. 495,668 In France May 2, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires May 2, 1960 18 Claims. 1
The present invention relates to electron discharge devices and more particularly to electron discharge devices in which a beam of electrons is controlled in such a way as to effect a modulation of velocity of the electrons along the beam.
The invention particularly aims at providing types of electron velocity modulated devices that are sturdy and of small size and consist of such elements that use can be made during manufacture of the methods for pumping and sealing that are customary in the art of electron discharge tubes.
The invention is explained in the following description of one special example of an embodiment shown in the appended drawings, in which:
Fig. l is a longitudinal view, partly in section, of a type of electron velocity modulating device that incorporates features of the invention;
Fig. 2 shows a section of the base of the device taken along the line 22 of Fig. 1;
Figs. 3 and 4 are plan views of two supporting and spacing elements used in the device;
Fig. 5 is a cross-section taken along the line of Fig. 1;
Fig. 6 is a cross-section taken along the line E6 of Fig. l; and
Figs. '7 and 8 are enlarged views of details of Fig. 1 showing features of the invention.
The device incorporating features of the invention and shown as an example in the drawings comprises, within an evacuated insulating bulb i, a unit for generating a beam of electrons, an oscillatory circuit and an anode, all spaced along the axis of the device. The beam generating member and the oscillatory circuit are supported and fed from a base 2 of the insulating bulb, while the anode is supported from the other end of the bulb, as is also a transmission line disposed to collect energy from the oscillatory circuit.
The beam generating structure comprises a heating filament 3 disposed within an emissive cathode l. Cathode 4 is surrounded by a concentration cylinder 5 for concentration of the electrons emitted in a beam. This concentration can be effected either simply by means of the potentials applied respectively to cathode 4, cylinder 5 and the oscillatorycircuit, or else by means of an axial magnetic field applied by outside means (not shown).
The tuned oscillatory circuit consists of two cavity resonators 6 and 'l symmetrical with the axis of the structure that have two constricted portions 8 and 9 in the axial passage of the said oscillatory circuit. This unit may consist, as
shown in the drawing and according to features of the invention, of an outer cylinder I l and three walls [2, I 3 and I l, the axial passage It! being formed by margins of these walls. A more de' tailed description of the structure of this oscillatory circuit and of a preferred type of embodiment will be given further on.
The electron beam emitted by cathode 4 is accelerated by the positive potential applied to the oscillatory circuit on its passage through the first constriction 8; the grid or multiple opening portions l5 and it delimit this constriction 8 and insure the effect of electron velocity modulation by slowing the average velocity of a certain number of electrons and accelerating the average velocity of others by a known mode of operation. The beam, in which the electrons are grouped as a result of the velocity modulation thus produced, passes through the second constriction 8 which is similarly delimited by grid or multiple opening portions H and I8 and, in the lkewise well known manner, the electrons leave there a portion of their energy which is collected in the cavity resonator l by means of a transmission line. In the embodiment of the invention shown in the drawing, this transmission line consists of a 3-wire line having the conductors located in the same plane, the middle conductor !9 passing through an opening 28 in wall 14 to form a loop 2| coupled to the resonator cavity '5 and which is delivered to an output device, the two other conductors 22 and 23 (Fig. 6) being directly secured to the outer face of this wall it. The three conductors of this transmission line issue from the insulating bulb through seals shown at 24 in Fig. 1.
The beam that issues from the oscillatory circuit strikes the anode 25 which is supported by a rod 28 in a tight seal 21. The anode may be at the same potential as the oscillatory circuit or at a higher potential or even at a potential lying between the potentials of the oscillatory circuit and of the cathode.
The oscillatory circuit is mounted on three rigid rods 28 which are soldered on collars 29 that consist, for example, of several circular are elements assembled by means of screws and nuts as shown at 30. The soldering of the rods on the collars is done with the aid of brackets as shown at 31. The collars 29 are looked around the base 2 of the insulating bulb by means of screws. The electrical connection of the oscillatory circuit is provided by these rods 28 by means of a lead-in wire 32 which passes inside of the base 2, as shown in Figs. 1 and 2, through a herinetic seal into the interior, being soldered on a short length of wire or rod 33 which is itself secured, for example, by soldering, to one of the rods 28.
These rods 28 likewise support the beam gencrating unit by means of a mounting plate or spacing disc 35 of mica or other suitable insulat ing material, as shown inplan view in Fig. 3. This mica disc 36 comprises a central aperture .35 for the centering of the cathode, and openings The points for t 3 This insulating disc is made in this way and is installed, according to one feature of the invention, in such a way that the cathode is insulated from the concentration cylinder and is at the same time always centered with respect to the axis of the oscillatory circuit.
Furthermore, according to another feature, the insulation of the concentration cylinder 5 of the cathode with respect to the supporting rods 28, and of the oscillatory circuit is increased by three notches 33- cut out in the mica in such a way that the distance along the surface of the mica between the contact points 35 of rods'23 and the concentration cylinder 5 is increased. The con centration cylinder 5 is maintained in suitable spaced relation from the oscillatory circuit, for example, by means of clips 39 that secure the mica disc on the rods 28. This spacing can be adjusted during the fitting in such a way that the current of desired voltage that passes through the circuit may have the right value for the desired. operation. The feed connections of cathode t, of filament 3 and of the concentration cylinder 5 are carried through the base 2, as shown at ll) in Fig. 1.
As seen in Fig. 7 rods 5 are secured to spacing disc 3 at points 3? as by sealing and rigidly secured as by brazing to concentration cylinder 5. Rods 54% extend through disc 35 and a wire 55 connects the cylinder 5 to one of the feed connections ill. Cathode is centered in holes 35 in disc 33 and supported from the envelope as by rods 53. Rod 58 is brazed to cathode 4 and connected by wire 5i another one of the feed connections iii. Filament 3 is supported inside cathode 4 and wires 59 connect it to two other of the feed connections ii The oscillatory circuit is kept centered in the bulb l by means of the centering or aligning member of insulating or metallic material to which secu ed by screws, shown at 2. This contering member is shown in plan view in Fig. 4. It is provided, according to one feature of the invention, in such a way that the weight of the circuit and that of the base vith the other assembled elements substantially balance each other in such a way as to facilitate the operations of scaling in the entire unit. This centering member is provided so as to have a certain elasticity in the direction of the axis of the device and not to be rigid against the walls of the insulating bulb l. Thisarrangement is specially desirable on account of the weight of the cavity resonators and 7.
Connection 2% is to be kept relatively cool in order to insure the'hoidingup of seal 21, that is, in order to avoid stresses that might cause cracks alongside it in the insulating material of the bulb, for example, glass. For this purpose and according to one variation of the invention, th anode for example, of molybdenum, is made of conical shape with cooling ribs it With an anode of this shape, the cooling surface increases with approach to connection 26 and the conduction of heat diminishes. The anode 25 is jointed to connection 26 by an elbow member soldered on a little plate it that is secured to a disc 41 which has a surface substantially equal to the input surface, and this also helps the cooling. The anode 25 is screwed in this disc 41.
In order to increase the dissipation of heat and thus lower the temperature of the oscillatory circuit and of the anode, these two elements are coated with a material such as colloidal graphite which gives a surface having a high coeflicient of radiation. The insulating bulb is preferably made of hard glass in order to increase the power that can be dissipated without danger of damaging the glass, and in order to provide this bulb with a high electric resistance.
It is to be observed that the construction of the oscillatory circuit in devices that incorporate features of the invention is particularly simple and eificient. This oscillatory circuit is made of copper, for example, on account of the high conductivity and high expansion coefficient of this material. As mentioned, the body of this circuit only comprises four members, namely the cylinder ii and the three transverse walls l2, l3 and i i. Each of these walls comprises the marginal portion required for defining the axial'conduit l3. Wall [2 contains only the openings 42 for passage of the screws or rods for securing the oscillatory circuit to the supports 23. Wall 13,
according to one feature or" the invention as shown in Fig. 5, is given such a shape that it providis coupling slots between the resonant cavities i and ii in order to bring about a return of energy from the second cavity 1 to the first cavity E3 so as to enable the device to operate as a gene erator of oscillations in the known manner. Since it is necessary to have cavities 5 and I of the same natural frequency, a means for adjusting the resonance of cavity 7 is provided whenever a coupling of this kind is not suflici'ontly tight. This means consists of a wire or rod of the shape shown at 28 that is supported by a plug 19 passing through the wall i l. The natural frequency or" cavity '1 is varied by rotation of the plug it and it is thus brought to the same value as that of cavity 5. A locking screw 5 1 permits plug 49 to be held in place. However, this method of adjustment is not necessary if the slots 55 in wall [3 provide sufficiently tight coupling between the cavities 6 and l.
The outer cylinder ii is first made of normal dimensions. Then the central mymber I3 is adapted to the inside of cylinder ii in the following This member 3 is given a size slightly larger than the inside diameter of cylinder H it is cooled in liquid air and this reduces its diameter and permits it to be tted in place. It is then kept in this position by means of a. cylindrical brace until it has come back to the ambient temperature, and it then adheres firmly. to the walls of cylinder ii. Split pins (not shown) may be inserted in holes in cylinder I l to insure complete rigidity of the member l3 within the cylinder. The walls l2 and M are then put in place in the same manner, their respective spaced relation being maintained during the operation by means of suitable braces inserted and drawn through slots 53 in cylinder II.
According to another variation of the inven tion, the oscillatory circuit assembled in this way is then subjected to a series of thermal treatments in a vacuum or in a reducing or neutral atmosphere. A circuit made of copper or other metal that is heat treated in this way to a temperature close to melting point undergoes transformation that unites the points of contact of the various parts of which it consists in such a Way as to produce a structure that is practically integral. The union of the parts is almost per feet from the electrical viewpoint, even though the brazing may not be complete, and this is essential owing to the high circulation currentvalues during the operation of the assembled unit as an oscillatory circuit.
In order to provide contact at the edges of walls l2, l3 and 14, but not at their centers, these edges are made slightly concave, as shown at 52 in the drawing, Fig. 8. Hence each of the edges of walls [2, I3, and It has a peripheral groove. This measure insures in this way the shortest actual path for the high frequency currents.
It must be understood that the described type of construction may undergo numerous modifications without departing from the scope of the invention. In particular, one or more grids may be provided, for example, a control grid located between the cathode and the oscillatory circuit for the purpose of modulating the intensity of the electron beam. The electron beam generating unit may also be modified. In the oscillatory circuit it is possible to omit the grids or multiple opening passages |5--l *5 and |ll 8 and leave the axial conduit Ii without any obstruction. Furthermore, the anode structure shown in the drawing may be modified and it may be disposed in such a way as to have its cooling efiected by circulation of a refrigerant liquid either outsidecr inside the insulating bulb.
Further modifications and adaptations will hecome obvious to one skilled in the art without departing from the scope of the invention.
What is claimed is:
1. A cavity resonator electron tube construction comprising an envelope, a cathode supported on one end of said envelope, a cavity resonator enclosed in said envelope and spaced from said cathode, means carried by said envelope supporting said resonator in spaced relation with respect to said cathode, while retaining the oath ode in its position, aligning means for said resonator engageable with the inside surface of said envelope, and an sup-ported on the other end of said envelope.
2. A tube construction according to claim 1 in which said envelope includes a reentrant stem and wherein said supporting means comprises means for mounting the resonator on the inner surface of said stem to determine the spacing between the cathode and the resonator.
3. A tube construction as set forth in claim 2 in which said supporting means comprises supporting rods connected to the resonator and clamped about the stem.
4. A tube construction as set forth in claim 1 in which said aligning means comprises a plate carried by the resonator and engaging the inside of the envelope, thus maintaining the resonator in spaced relation with the envelope.
5. A cavity resonator tube construction comprising an envelope, a cathode supported on one end of said envelope, an anode supported on the other end of said envelope, and a cavity resonator unit arranged therebetween, said unit including a cavity resonator spaced from said cathode, supporting means for said resonator mounted on the said one end of the envelope, aligning means mounted on said resonator and pressed against the inside surface of said envelope, and an electron concentration cylinder insulatingly mounted on said supporting means and arranged about said cathode and spaced from said resonator.
6. A cavity resonator tube construction according to claim 5 further including a sheet of insulating material carried by said supporting means and supporting said concentration cylinder at a distance from said resonator, said sheet being apertured and in lateral engagement with said cathode for alignment of said cathode with said resonator.
'7. A cavity resonator tube construction comprising an envelope, a cathode mounted on one end of said envelope, a cavity resonator in said envelope, rods carried by said envelope supporting said resonator body adjacent said cathode, an electron concentration cylinder arranged about said cathode, and insulating means carried by said rods supportin said concentration cylinder at a distance from said resonator.
8. A cavity resonator tube construction according to claim 7 in which said mounting plate is provided with holes through which said rods pass freely and which further comprises slidable clips mounted around said rods securing said mounting plates to said rods for determining the longitudinal position of the mounting plate with respect to said resonator body.
9. A method of constructing a cavity resonator having an annular outer wall and a transverse partition therein which comprises forming the partition with a diameter slightly greater than that of the outer wall at normal temperatures, chilling the partition to reduce its diameter to dimensions not greater than the internal diameter of the outer wall, inserting the partition within the outer wall and raising the partition to normal temperature thereby increasing its diameter and forcing it firmly against the outer Wall.
10. A method as set forth in claim 9, in which the method includes a subsequent heat treatment in a non-oxidizing atmosphere to a temperature approaching the melting point.
11. A method of constructing a cavity resonator having an outer surrounding wall member and a transverse wall member therefor which comprises forming said members so that an external dimension of said transverse wall member is slightly greater than an internal dimension of the outer wall member at normal temperatures, changing the temperature of one of said members so that the dimension of said transverse wall member is less than the internal dimension of said outer wall member, inserting said transverse wall member within said outer wall member and returning to normal the temperature of the member whose temperature was changed thereby forcing the members firmly together.
12. A method of constructing a cavity resonator having an outer surrounding wall member and a transverse wall member therefor having face surfaces and an edge surface, said method comprising forming said members so that an external dimension of said transverse wall member is slightly greater than an internal dimension of the outer wall member at normal temperatures and forming said transverse wall member with a periphery dimension of a portion of said edge surface being greater than a periphery dimension of the remainder of said edge surface, changing the temperature of one of said members so that the dimension of said transverse wall member is less than the internal dimension of said outer wall member, insertin said transverse wall member having the greater periphery dimension within said outer wall memher and returning to normal the temperature of the member whose temperature was changed thereby forcing the outer wall member and the edge surface of the transverse member having the greater periphery dimension firmly together.
13. A'cavity resonator tube construction comprising an envelope, a cathode supported on one end of said envelope, an anode supported on the opposite end of said envelope, a cavity resonator arranged between said cathode and anode including a peripheral wall and a number of parallel transverse walls marginally engaging said peripheral wall, one of said transverse walls having an outer margin provided with a recessed portion engaging the peripheral wall on either side of said recessed portion, means supporting said resonator disposed between said one end of said envelope and another of said transverse walls, and means electrically connecting said resonator through a third of said transverse walls and sealed through said envelope at said opposite end.
14. A construction as set forth in claim 13, wherein said transverse walls consist of spaced metal discs, coaxially arranged, surrounded by a metal cylinder forming the peripheral Wall of the cavity.
15. A cavity resonator construction comprising a peripheral wall and a number of parallel transverse walls marginally engagin the peripheral Wall to form a cavity resonator, one of said transverse walls being arranged between adjacent walls and having an outer margin provided with at least three recessed portions and engaging the peripheral wall with marginal portions diametrically opposite said recessed portions, means supporting said cavity resonator on another of said transverse walls, and means electrically connecting said resonator through a third of said transverse walls.
' 16. A cavity resonator tube construction com prising a sealed insulating envelope, a cathode supported on one end of said envelope, a cavity resonator enclosed in said envelope and spaced from said cathode, supporting mean for said resonator'mounted on said one end of the envelope, aligning means for said resonator supported on the inside surface of said envelope, an anode enclosed in said envelope and spaced from and aligned with said resonator, and means extending in the direction of said alignment, from said anode away from said resonator and supporting said anode on said envelope, said anode comprising a body having a decreasing taper in the direction of said alignment away from said resonator and a plurality of radial, trans-axial head radiating fins mounted on said body.
17, A tube construction as set forth in claim 16 in which said anode includes a conical body aligned with said resonator having its larger end adjacent said resonator, an end plate mounted on the smaller end of said conical body and supported by the envelope, and a number of spaced plates parallel to said end plate forming heat 7 radiating fins.
18. An anode for a discharge tube having a cathode said anode comp-rising a conical body having its larger wall facing said cathode, an end plate mounted on the smaller end of said body, a number of spaced plates parallel to said end plate forming heat radiating fins, and a lead out conductor connected to said end plate.
TREVOR H. CLARK. ANDRE GABRIEL CLAVIER. ERNEST ROSTAS.
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