US2900561A - Electron discharge device - Google Patents

Description

Aug. 18, 1959 R. s. GORMLEY ELECTRON DISCHARGE DEVICE 2 Sheets-Sheet 1 Filed Dec. 15, 1953 INVENTOR. ROBERT 3. GORMLEY ATTORNEY Aug. 18, 1959 R. s. GORMLEY 2,900,561

. ELECTRON DISCHARGE DEVICE Filed Dec. 15, 1953 2 Sheets-Sheet 2 r IOS VII/I113 INVENTOR.

4? ROBERT s. GORMLEY ATTORNEY United States ELECTRON DISCHARGE DEVICE Robert S. Gormley, West Long Branch, N.J., assignor to Bendix Aviation Corporation, Eatontown, N.J., a corporation of Delaware Application December 15, 1953, Serial No. 398,321

1 Claim. (Cl. SIS-5.23)

must be focused through gridded aperture .040" in diameter, thence through another gridded aperture .052" in diameter into a retarding repeller field which returns the beam through the .052 diameter grid. Due to the fact that a portion of the electron beam current is lost through interception on the grid wires as it passes through the grid, it is necessary that substantially all of the beam passes through these apertures with as little as possible being intercepted on the edges of the frames supporting these grids. In addition, the retarding repeller field must return the electrons in all parts of the beam at a given time at substantially the same R.F. phase in order to produce the RF. output energy. The former requires extremely accurate concentricities between component parts and the latter dictates a high degree of axial alignment of the reflector assembly.

The present invention provides novel modifications for greater accuracy in locating critical component parts and to reduce critical assembly operations. The various modifications permit the use of simple assembly jigs and fixtures yet accurately locate the component parts. Further the modifications increase the reliability of the tube structure, thus permitting operation under shock and vibration conditions without failure or degradation of the performance characteristics.

It is an object of the invention to provide an improved reflex oscillator of the cavity resonator type.

- Another object of the invention is to provide an improved ruggedized electron discharge device.

Another object of the invention is to provide an improved electron discharge device that may be readily assembled yet maintain critical dimensions.

Another object of the invention is to provide proved and novel structure for an electron discharge device.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example.

In the drawings:

Figure 1 is a sectional view to an enlarged scale of an electron discharge device illustrating an embodiment of the invention. Figure 2 is a fragmentary view illustrating one feature of the invention.

Figure 3 is a sectional view of the assembly shown in Figure 1 taken along the line 3-3.

-"atent 2,900,561 Patented Aug. 18, 1959.

. comprises a cylindrical portion 11, which may be any suitable material such as metal, having an outwardly extending flange 12 on one end and a counterbore portion 13 on the other end thereof. A dished base or platform 14 is hermetically sealed to the flange 12 as will be ex-' plained in detail later. An inverted cup shaped member 15 has an outward extending flange 16 terminating in a cylindrical flange 17. The flange 17 is inserted in the counterbore section 13 of the envelope 10 and positioned by a shoulder 18. The member 15 is brazed to the wall section 11 to provide a vacuum tight joint therewith. The member 15 is provided with a central aperture in its base in which a window 19 highly transparent to electromagnetic waves is sealed in a conventional manner.

Mounted within the enclosing vessel is a unitary assembly comprising a radio frequency unit including a reflex oscillator of the cavity resonator type and a wave guide output line or section for the oscillator, and including also a triode unit for tuning the cavity resonator. The components of this unitary assembly are built around a rectangular plate 20 of a metal having high heat conductivity. The plate 20 extends into and is fixed in a slot ina relatively massive cooling block 21, also of a metal having high heat conductivity, which is secured by brazing to the wall 11 of theenvelope 10 and constitutes the support for the unitary assembly. The block 21 is provided with recesses 22 for receiving pellets of a brazing material. The plate 20 and block 21 are coupled to base 14 by a pair of flexible metallic members 23, the function of which will appear presently.

The plate 20 is provided with a circular opening-2.4, defining a part of a cavityresonator. Three pilot holes 25 are provided in the plate concentric with the opening 24; The pilot holes 25 are located so that pins through these holes will nest and locate the various parts. A slot or cutout portion 26 extends from one edge of the plate 20 and having a restricted rectangular portion 27 opening into the opening 24, the slot defining a wave guide output section for the cavity resonator. Aflixed to one face of the plate 20 is a circular, metallic frame or support 28 having a frusto-conical portion 29 mounting a dished or concavo-convex grid 30 composed of fine parallel wires. Affixed to .the other face of the plate 20 is a retaining ring 3 1 which clamps an annular metallic diaphragm 32 to the face. The diaphragm 32 is circularly and concentrically corrugated and mounts an annular metallic support or frame 33 which carries a dished or concavo-convex grid 34 composed of fine parallel wires. The pilot holes 25 enable the aforementioned parts to be located with a high degree of accuracy. Pilot pins may be located in the welding electrodes, so that the parts are located and welded in the same fixture with the accuracy of location being dependent upon the parts and tools rather than by the assembly operation.

The 'grids 3t) and 34-, frusto-conical support 29, dia' phragm 32 and the circular walls of the opening 24 in. the plate 20 bound a cavity resonator which is tunable by flexure of the diaphragm 32 and from which power may be taken by way of the restricted portion 27 of the slot or cut-out portion 26 in the plate 20 and a wave guide 35.

The wave guidefis. is formed of sheet metal, is of 3 rectangular section throughout and tapers from the cavity resonator towards the window 19, thereby to provide a uniform impedance along its its length. The guide 35 tits in the cut-out portion 26 in the plate 20 and at its inner end has portions 36 overlying and aflixed to the grid frame 28 and retaining ring 31.

At its upper end, the wave guide 35 is secured to an inverted, cup-shaped metallic member 37 having an encircling flange 38 to provide a choke joint adjacent to the envelope 10, thereby to minimize loss of electromagnetic energy propagated through the guide 35 and winddow 19. The member 37 is secured to a cylindrical support or mount 39 having a flange 40 which is provided with integral fingers or tabs 41 affixed to the plate 20.

Cooperatively associated with the cavity resonator are an electron gun and a repeller electrode to constitute a reflex oscillator therewith. The electron gun comprises a metallic cathode member 42 having a cylindrical body portion 43 and a dished end portion 44, the concave face of which has a coating 45 of electron emissive material thereon. Disposed therein the cathode member 43 is a heater element 46, for example, a double helical filament coated with an insulating material. The cathode member 42 is supported within a flanged cylinder 47 by means of support wires 48 located at each end of the body portion 43. The support Wires are of a material having low heat conductivity such as Nilvar. The cylinder 47 has a flange 49 aifixed to a focusing electrode 50 by welding to an annular flange 51 thereon which surrounds a central cylindrical portion 52. An insulator 53 is provided to support the cathode heater 46. The insulator 53 (see Figure comprises a mica strap 54 having metal tabs 55 and 56 crimped in place. The tabs 55 are used for connecting the assembly to the cylinder 47 and the tabs 56 are used for connecting the heater conductors 57. The focusing electrode 50 is'secured to an insulating disc 58 by bent over tabs 59 struck from the flange 51. The disc 58 is locked against an internal shoulder in a dished mounting member 60, by a locking band or collar 61, the mounting member 60 being secured to the flange 36 of the support for the grid 30. The gun comprises a concavo-convex accelerating and focusing grid 62 carried by the base of the mounting member 60.

The repeller electrode comprises a cylindrical head por tion 63 having a concave face 64, and a shank port-ion 65 which is fitted in a mica insulating disc 66. The disc 66 is held against the head portion 63 by a locking sleeve 67 afiixed upon the shank 65. The disc 66 is fitted tightly within a metallic sleeve 68 which abuts and is aflixed to the diaphragm 32. The sleeve 68 is spaced from the head portion 63 and is fitted within and afiixed to a rigid cylindrical drive member 69 having an end flange 70 and an intermediate external collar or flange 71. The shank 65 is maintained in alignment by a ceramic insulator 72 fitted into the outer end of the drive member 69.

A U-shaped metallic bracket 73 is secured to the flange 70 and mounts an insulating plate or strip 74 against which a thin, flexible metallic strap 75 is locked by a metal eyelet 76 affixed to the shank 65. The strap 75, together with a conductor 77 sealed to an eyelet 78 on the base 14 by a vitreous head 79, constitutes the lead in connection to the repeller electrode. It will be noted from the construction that this electrode is insulated from the cavity resonator defining members and hence, may be operated at a potential different from that of these elements.

The assembly comprising the repeller electrode 63,

The tuner unit is carried by a metallic support 80 aflixed to one end of the plate and having outer arms 81 and an intermediate arm 82. It comprises a pair of metallic struts 83 and 84 of the same material, for example stainless steel, which are secured at one end to the intermediate arm 82 and at the other end to the collar or flange 71 on the drive member 69. The struts 83 and 84' are both provided with a longitudinal flute, the strut 83 extends substantially normal to the arm 82 and the strut 84 is inclined relative to the strut 83. In order to locate the tuner assembly accurately, pilot holes 85 are provided in the arms 81. Pins extended through the holes 85 permit the assembly to be located with extreme accuracy. The pins may be part of a small fixture which can be withdrawn after the assembly is located and welded in place.

It is apparent that if one or both of the struts are I heated, because of the relative disposition and expansion sleeve 68 and drive member 69 which is coupled to the of the struts, the ends of the struts secured to the flange or "collar 71 and, hence, the unitary assembly including the repeller electrode, will be displaced in the direction substantially parallel to the longitudinal axis of the repeller electrode. The direction and amplitude of displacement as the temperature of the struts changes will be determined by the sign and magnitude, respectively, of the temperature changes. Such temperature changes are accurately controllable in both sign and magnitude, by utilizing the strut 83 as the anode of an electronic unit and controlling the electron current to this anode.

The electronic unit comprises a pair'of insulating plates or spacers 86 which are supported by a metallic frame or housing 87 having flanges 88 afiixed to the support arms 81. Mounted by the spacers 86 in alignment with the strut 83 are a cathode 89.0f rectangular cross section and heatable to emission temperature by an insulated, folded heater filament 90, and a rectangular grid 91 carried by support rods or wires 92. The potential of the grid is appropriately varied to control the electron current to, and hence, the temperature of the strut anode 83, thereby to tune the cavity resonator to the desired frequency.

A thin, flexible strip 93 of high thermal conductivity material, such as copper, is connected at one end to the unitary assembly including the repeller electrode, specifically has an end portion clamped between the drive member 69 and sleeve 68, and has its other end aflixed to the plate 20. The strip 93 functions as a heat bleeder or thermal shunt, to conduct heat away irom the drive member 69 and, thus, to minimize the effect of heat generated at the cavity resonator during operation of the device, upon the tuning struts. It tends to hold the temperature uniform over the cavity resonator system, where by the eifect of heating of the resonator upon the thermal tuning system is minimized and the tuning system is quickly responsive to changes in potential of the control grid 91.

Electrical connection to the various electrodes of the reflex oscillator and the thermal tuner element include conductors 94 sealed in eyelets 95 on the base 14 by vitreous beads 96. The conductors 94 extend to terminal pins 97 carried by an insulating base 98 which is provided with a stem 99 enclosing metallic exhaust tubulature 100, and is coupled to the base 14 by a metallic mounting ring 101.

The mounting ring 101 has a flange 102 which together with the base 14 and flange 12 of the wall sectionll are joined to form a vacuum tight seal by a ring weld 103. The ring weld 103 is produced by using two copper rings 104 placed in troughs 105 produced by forming Welding beads 106 around the flanges 12 and 102 (see Figure 2). By this means, the welding bead maintains its shape upon application of the necessary welding pressure and consequently maintains a narrow area of contact in which to make the weld. The result is a more reliable weld and requires less power to make the weld.

An insulating wave guide coupler 107 encompasses the cup-like member 15 of the envelope and is affixed thereto by spinning over a section 108 of the wall section 11. Due to the insulating character of the coupler 107, the envelope 10 of the device is separated from the external wave guide and hence, may be at a high potential without danger of such potential appearing on the external wave guide.

The internal structure as heretofore set forth may be fabricated from a plurality of subassemblies in which the constituent elements are accurately positioned in prescribed relationship to one another. These assemblies are then joined into a unitary mount assembly and accurately positioned relative to one another and mounted on the plate 20.

After the base 14 has been scaled to the flanges 12 and 102, the assembly is heated so that the solder pellets in the recesses 22 in the block 21 melt and braze the block 21 to the wall 11 thereby providing a rigid and strong support for the internal elements. A spring 109 aids in holding the block 21 into contact with the wall 11 until the brazing is completed. A device is provided by the heretofore set forth structure and methods that is capable of withstanding relatively strong shock and vibration without alteration of the relation of the internal elements or impairment of operation of the device.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

In an electron discharge device having a supporting plate forming the walls of a cavity resonator, an electron gun comprising a cylindrical cathode, a heater element ex tending into said cathode, a flanged cylinder, means for supporting said cathode in said cylinder at each end thereof, a focus electrode, and means for securing said flanged cylinder and said focus electrode to said supporting plate concentric relative to each other.

References Cited in the file of this patent UNITED STATES PATENTS 2,439,908 Rigrod Apr. 20, 1948 2,468,145 Varian Apr. 26, 1949 2,494,693 Ekstrand et al. Jan. 17, 1950 2,513,277 Best July 4, 1950 2,513,359 Pierce July 4, 1950 2,513,371 Shepherd July 4, 1950 2,632,231 Brown- Mar. 24, 1953 2,635,207 Goddard Apr. 14, 1953 2,709,294 Jimenez May 31, 1955 2,765,423 Crapuchettes Oct. 2, 1956 2,786,185 Sege et al. Mar. 19, 1957

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