US2878415A - Electron discharge device - Google Patents

Description

'R.S.GORMLEY EI'AL 2,878,415

March 17, 1959 ELECTRON DISCHARGE DEVICE 2 Sheets-Sheet 2 Filed march 31, 1955 FIG. 2

ROBERT S. GORMLE Y ROBERT G. JOHNSON WESLYE L. MART/N IN VEN TORS.

' ATTORNEY United States Patent ELECTRON DISCHARGE DEVICE Robert S. Gormley, West Long Branch, Robert G. Johnson, Neptune, and Weslye L. Martin, Park Ridge, N. L,

assignors to Bendix Aviation Corporation, Eatontown, N.J., a corporation of Delaware Application March 31, 1955, Serial No. 498,236

2 Claims. 01. 2.15-5.21

I, The present invention relates to electron discharge devices and more particularly to reflex oscillators of the cavity resonator type.

t In a reflexoscillator, such for example, a klystron, due to the requirements for operation at high frequencies, the dimensions of the critical component parts are of necessity small in physical size. Accordingly, the concentricities and axial alignment of the parts become of I member 27 is secured to a cylindrical the'design' of the cavity together with the repeller and gunassembly, provide a rigid, rugged blockdike structure in which critical dimensions may be easily maintained. Further, frequency' stability is improved for operation under conditions of acceleration, shock or vibration; In addition, an improved tuning mechanism ispprovided,

Itis an object of the invention to provide an improved ruggedized electron discharge device.

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

Another object of the invention is to provide an improved tuner for a cavity resonator.

Another object of the invention is to provide an improved tunable klystron.

The above and other features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawings 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 one embodiment of the invention.

Figure 2 is a cutaway view of the device of Figure 1 illustrating the tuner mechanism.

Reference is now made to the drawings wherein similar parts in the various figures have been assigned the same reference numerals, the electron discharge device therein illustrated comprises, generally, a highly evacuated envelope and a mount fabricated of several subassemblies united into an integral structure which is inserted in the envelope as a unit and supported from the sidewall thereof.

The envelope, indicated generally by the numeral 10, 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. A

Patented Mar. 17, 1959 2 mounting ring 15 may also be secured to the flange 12. An inverted cup-shaped member 16 has an outward extending flange 17 terminating in a cylindrical flange 18. The flange 18 is inserted in the counterbore section 13 of the envelope 10. The member 16 is brazed to the wall 11 to provide a vacuum tight joint therewith. The member 16 is provided with a central aperture in its base in which a window 20, highly transparent to electromagnetic waves, is sealed in a conventional manner.

Inclosed within the envelope 10 is a cavity plate 21 positioned by and secured to a cooling block 22. The block 22 is secured to the wall 11 by brazing and provides mechanical support. In addition, the block 22 conducts heat generated withinthe deviceto the outer wall 11. The plate 21 has a circular opening 23, defining a part of a cavity resonator. A slot or cutout portion 24 extends from one edge of the plate 21 and has a restricted rectangular portion 25 opening into the circular opening or cavity 23. The slot 24 defines a. wave guide output section for the cavity resonator and connects to a tapered output waveguide 26. At its upper end, the wave guide 26 is secured to an inverted, cupshaped metallic member 27 having an encircling flange 28 to provide a choke joint adjacent to the envelope 10, thereby to minimize loss of .electromagnetic energy propagated through the guide 26 and window 20. The support or mount 'ice Afiixed to one face of the plate 21 is a circular, metallic frame or support 29, having a frusto-conical portion 30 mounting a grid 31 composed of fine wires. The frame 29 is located so that the grid 31 will be concentric with the cavity opening 23. An accelerating grid 32 is secured to a dished mounting member 33 which is secured to and concentric with the frame 29. On the opposite side of the plate 21, a flanged sleeve 34 is secured to the plate 21 and positioned concentric with the circular opening 23. An upper cavity grid 35 is secured to a grid support 36 positioned in the sleeve 34 and secured thereto. The grid 35 is concentric with the grids 31 and 32.

An electron gun assembly 37 is supported in the dished member 33. The electron gun assembly includes a concave oxide-coated cathode 38 supported in a flanged cylinder 39 by support wires 40. The wires 40 are of a material having low heat conductivity such as Nilvar. A heater 41 is provided for the cathode 38. A beam forming electrode 42 is secured to the flange of the cylinder 39. The assembly is positioned concentric with the grids 31, 32 and 36 by insulators 43 and 44 in the dished member 33 which is crimped to hold the assembly in position.

The repeller assembly includes a repeller 45 secured to a support wire 46 which is anchored in a ceramic insulator 47 by metalizing and brazing or in any other suitable manner. The insulator 47 nests within the sleeve 34 and the repeller 45 extends into an opening in the grid support 36. The sleeve 34 is crimped to hold the assembly in position. The repeller 45 is concentric with the grid 35.

Reference is now made to Figure 2 wherein a tuner assembly is illustrated for tuning the cavity by inserting a dielectric rod in the fringing electric field surrounding the interaction grids of the cavity. A dielectric tuner rod 48, such for example as a sapphire rod, extends radially into the cavity 23 through an opening 49 in the cavity plate 21. In order to minimize leakage of energy from the cavity, the opening 49 is inclosed to form a waveguide beyond cutoff. The rod 48 is secured in a metallic supporting sleeve 50. The sleeve 50 is secured to a support wire 51 which is in turn secured to a tuner plunger 52. The plunger 52 has a threaded section 53 adapted to engage an internal threaded section 54 of a tuner screw 55. External threads 56 of the screw 55 engage a threaded bushing 57 secured by screws 58 to a tuner casing 59. The casing 59 extends into the envelope 11 and is sealed therewith. A loading spring 60 is inserted between the bushing 57 and plunger 52 to reduce backlash due to the tolerances of the screw threads. A bellows 61 brazed to the tuner casing 59 and the tuner plunger 52 forms a vacuum tight seal for the tuner mechanism. The tuner plunger 52 has a counterbored portion 62, surrounding the sleeve 50, and extending into a cylindrical portion 63 of the casing 59. The cylindrical portion 63 serves as a guide for the plunger 52. The counterbored portion 62 is relieved to reduce the contact area with the cylindrical portion 63 and also to facilitate exhausting the bellows area.

The construction of the device, as set forth heretofore, lends itself to the production of a device that "is rugged and will maintain frequency stability within very narrow limits under conditions of acceleration, shock or vibration. The tuning of the cavity is capacitive and is accomplished by radial movement of the dielectric rod in the fringing electric field surrounding the interaction grids of the cavity. Radial motion of the rod relative to the cavity and electric field changes the effective gap capacitance and hence the resonant frequency of the cavity. It is necessary that the tuner rod have a high dielectric constant, low R. F. loss, high mechanical strength, and be capable of operation in a high vacuum device at relatively high temperatures.

The support wire 51 provides a degree of flexibility during assembly and in the tuning operation. This flexibility does not substantially afiect frequency variations during acceleration, shock or vibration due to motion in a lateral or longitudinal direction. In a lateral direction, the rod is wider than the electric field and hence no substantial change in capacity will occur. Longitudinal motion is self-compensating due to the action of'the gap capacitances between the cavity walls and rod serving as two capacitances in series. As one of these increases, the other decreases so that the resultant capacitance is constant to the first order. The design of the tuner prevents radial motion under severe operating conditions.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangement of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the-invention.

What is claimed is:

1. In an electron discharge device having a support+ ing plate forming a cavity resonator of circular cross section, an electron gun, and a tuner assembly, a repeller assembly comprising a flanged cylinder secured to said supporting plate and located concentric with said cavity, a grid and a grid support washer of insulating material positioned in said cylinder and secured thereto, a repeller, a support wire connected to said repeller, a cylindrical insulator surrounding said support wire and secured thereto, said cylindrical insulator being positioned .in said flanged cylinder, and means for securing said insulator in said cylinder.

2. In an electron discharge device having a resonant cavity of circular cross section, a repelle-r assembly and an electron gun, a tuner assembly com-prising a dielectric member, an opening in said cavity having wall sections defining a waveguide beyond cutoff, means including a flexible support wire for supporting said dielectric member in said opening, means for actuating said dielectric member for radial-movement in said cavity, and sealing means between said dielectric member and said actuating means to provide a vacuum seal. I

References Cited in the file of this patent UNITED STATES PATENTS

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