US2400080A

US2400080A - Thermionic tube

Info

Publication number: US2400080A
Application number: US414502A
Authority: US
Inventors: William W Eitel; Jack A Mccullough
Original assignee: Eitel Mccullough Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1941-10-10
Filing date: 1941-10-10
Publication date: 1946-05-14
Anticipated expiration: 1963-05-14

Description

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THERMIONIC TUBE Filed Oct. 10, 1941 2 Sheets-Sheet 1 INVENTORS WILL/AM W E/TEL THEIR ATTORNEY May 14, 1946. w. w. EITEL ET AL THERMIONI C TUBE Filed Oct. 10, 1941 2 Sheets-Sheet 2 M .LU

N M MA w d b w A T TO RNE YS.

Patented May 14, 1946 UNITED STATES PATENT OFFICE THERMIONIG TUBE fornla Application October 10, 1941, Serial No. 414,502

18 Claims.

Our invention relates to a vacuum tube, and more particularly to a thermionic tube.

It is among the objects of the invention to provide an improved multiple-unit tube having a pluralityof thermionic operating unitsdisposed within a single envelope.

Another object is to providebn improved anode structure.

Another object is to provide improved means for mounting and establishing electrical connections with the electrodes of the several units.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments there n within the scope of the claims.

Figure 1 is a vertical sectional view through the envelope of a tube embodying the improvements of our invention, parts of the internal structure being shown in section and parts in elevation; and

Figure 2 is a similar view taken in a plane through the envelope at right angles to that of Figure 1.

Figures 3 and 4 are detailed views of the multiple anodes.

Figures 5 and 6 are respectively detail views oi the grid and cathode elements. V

Figure '7 is a fragmentary sectional view sho ing a modified plate mount; and

Figure 8 is a plan view showing a modified arrangement of the plate sections to produce a four-unit anode.

In terms of broad inclusion, our thermionic tube comprises a plurality of units within an envelope, each unit including an anode, grid and cathode. The anodes are provided with transversely extending heat radiating fins, each common to a pair of anodes. The anodes are also preferably formed in sections, a section of one anode being integral with that of another. An improved arrangement of leads is provided for supporting the anodes and grids in the envelope. and an improved mounting structure is provided for the cathodes.

In greater detail, and referring to Figures 1 to 6 of the drawings, our improved thermionic tube comprises a glass envelope 2 enclosing a pair of units each including an anode 3, grid 4 and cathode 6. The envelope is cylindrical in shape, having a top dome I and joined to a reentrant stem 8 by a base flare 9. In a tube having a pair of units disposed about axes spaced say inch and each having an anode diameter of about /2 inch, the diameter of the envelope is about 2 inches. This gives a relatively close spacing be- 5 tween the envelope side walls and an electrode for purposes of making short leads. Additional clearance is provided about the anodes by a circumi'erential bulge ll preferably lying substantially between planes defined by the ends of the anodes. This removes the glass from the heat zone about the anodes; the annular recess formed by the bulge providing the greatest spacing at the mid section of the anodes where heat is greatest.

Referring particularly to Figures 1 to 4, anodes 3 are made of cylindrical sections l2 joined endto-end, with a section of one anode integrally connected to a section or the other by a flange I! which functions as a heat radiating fin. An

annular recess or seat It is preferably provided at the flanged end of each anode section so that the sections may be nested. After assembly the nested sections are secured together, preferably by welding. This provides a pair of spaced cylindrical anodes having a plurality of heat radiating fins extending transversely 01' and spaced therealong, each fin being common to a pair of the anode sections.

Figure 3 shows anodes each comprising six 0 main sections with a short section at the bottom to provide a base fin. It is to be understood that any desired number of sections may be employed, and that the height of the individual sections may be varied depending upon the spacing desired between the fins. The final anode assembly provides a rigid structure which is strong mechanically and radiates heat efliclently.

The integrally connected anode sections are preferably formed from a fiat metal sheet, such as tantalum, by drawing out cylindrical portions I! with a suitable die, leaving portions of the flat sheet to provide fin It. The bottoms of the cup-shaped sections produced by the drawing operation are then knocked out, providing pieces of the character shown in Figure 4.

After the anode sections are welded together, a plate ll having apertures registering with the hollow anodes is welded to the top fin. Hemispherical caps H are then welded in place over the anodes to protect the glass dome of the envelope against heat and electron bombardment.

The anodes are supported on the inner ends of a pair of aligned leads l8 extending through the envelope wall above bulge II. These leads 55 are disposed transversely of the anode axis and preferably lie in the same plane with the axis. They pass through seals at the ends of horns ll projecting from opposite sides of the envelope. Attachment to the leads is eifected by brackets 2| formed by upturned ends of plate II and terminating in sleeves I! welded to leads ll.

Grids I are preferably of the ordinary cage type having vertical wires held by a reinforcing spiral and terminating in a base ring II. The grids are rigidly connected by a metallic strap 2| comprising a pair of U-shaped pieces welded to rings it and welded together at the outturned flanges 28. forming a collar embracing the base rings and tying the grids together.

The connected grids are supported on the inner ends of a pair of leads 21 by tubular connections 28 each welded at one end to strap 24 and at the other end to a lead. Leads 11 are disposed transversely or the grid axis in the same plane with anode leads II, and extend through seals on horns 29 provided on the envelope below bulge N.

This arrangement of leads provides dual connections for the anodes and grids, whereby the electrodes may be interposed in external circuits to balance capacity. The envelope comtruction keeps the leads short; and alignment of the leads provides maximum spacing between the leads in each pair. These features are particularly important in a tube for high frequency work.

Cathodes I each comprise a filament wire supported at an upper mid point by a metal rod or standard II extending downwardly through lobe if in a four-lobed pinch on stem 8. The depending half portions or sections of each filament wire are coiled to form coaxial helixes; and the oathodes are connected in parallel by connectors I3 welded to the lower ends of the filament wires as shown in Figure 6. A pair of leads ll are welded to the mid portions of connectors I8 and extend downwardly through lobes 36 of the stem pinch. The structure thus comprises a pair of cathodes I each having a pair of downwardly extending helical filament sections supported at the upper ends thereof by a standard 3|: the lower end of a filament section in each pair being joined by a connector 38 which in turn is secured to a lead ll. Since the tube is designed for high frequency work the leads 34 preferably project directly out through the base of the tube to avoid the congestion in the usual pronged base structures.

Before the stem carrying the cathode structure is sealed in the envelope, the filaments are processed by heating in the usual manner. Our structure enables the filaments to be heated separately by connecting one leg oi a circuit to leads ll and another leg to one of standards 3!, which separate heating of the filaments is desirable when they are processed.

Prior to assembling the cathode structureln the envelope, a cup-shaped metallic shield I1 is mounted on the stem. The shield is split up one side and across the top as shown in Figure l to enable assembling it about the leads, and a slot It is provided in the top to give clearance about leads ll. The shield is grounded to standards 3| by welded lips as which also function to hold the split portions of the shield together. Apertures II in the sides of the shield allow air to be quickly withdrawn during the exhaust process.

Figure I shows a modified structure in which a single lead 42 is provided for the anodes. This lead is coaxial with the envelope and extends through a seal II in dome 1. The anodes are supported by a cone-shaped bracket 44 having a base flange welded to plate II and terminating at the top in a sleeve embracing lead It. The bottomofilieconeisovoidinshapeteprovidea bracket with flattened sides to fit between caps l'l.

With our improved sectional anode structure it is possible to build up units having any desired number of anodes. For example, Figure 8 shows a plan view of a unit comprising four anodes. This is made from pieces of the type illustrated in Figure 4, arranged in pairs with fins llof alternate pairs lying edge to edge and in the same plane. Cylindrical portions it of the pieces are nested together and welded as in the twin anode structure. In a similar manner, units with any desired number of anodes may be built up.

we claim:

1. In a thermionic tube, an envelope Having a stem, a pair of cathodes in the envelope and each having a pair of downwardly extending filament sections, a pair of standards extending upwardly from the stem and each connected to the upper ends of a pair of said filament sections, a connector secured to the lower end of a filament section in each pair, a second connector secured to the lower end of another filament section in each pair, and a pair of leads extendin upwardly from the stem and each secured to one of said conductors.

2. In an electronic tube, a pair of plate electrodes disposed about substantially parallel axes, and a sheet-like heat radiating fin interconnecting the electrodes and lying in a plane at substantially right angles to said axes.

3. In an electronic tube, a pair of plate electrodes each comprising a plurality of sections disposed end-to-end, and a plurality of fins interconnecting the electrodes and integral with sections thereof,

4. In an electronic tube, a pair of plate electrodes disposed side-by-side, and a plurality oi fins interconnecting the electrodes and lying in planes transversely of and spaced along the electrodes.

5. An electronic tube comprising an envelope, a pair of plate electrodes disposed side-by-side in the envelope, a plurality of fins interconnecting the electrodes and lying in planes transversely oi and spaced along the electrodes, a lead sealed to the envelope, and means for unitarily support. ing the electrodes on said lead.

6. In an electronic tube, a plate electrode comprising a plurality of hollow sections disposed end-to-end, each section having an end telescoped within the end of an adjacent section and secured thereto.

'1. In an electronic tube, an electrode structure comprising a plurality of parts each comprising a metallic sheet having a pair oi necklike sections integrally formed thereon, and means connecting the parts together with a section on one part aligned with that on another Part.

8. An electronic tube comprising a. vitreous envelope having a stem at one end, a pair of plate electrodes in the envelope, a grid associated with each of said electrodes and having a free end and a terminal end, conductor means sealed to the envelope intermediate the ends thereof, means tying the terminal ends of the grids together and supporting them on said conductor means, a cathode projecting into the grid, and conductor means for the cathode sealed to said stem.

9. An electronic tube comprising an envelope, a pair of plate electrodes disposed about substantially parallel axes in the envelope, a grid associated with each of said electrodes and having a free end and a terminal end, a pair of leads extending transversely of said axes and sealed to the envelope, and means tying the terminal ends of the grids together and supporting them on said pair of leads.

10. An electronic tube comprising an envelope, a pair of plate electrodes disposed about substantially parallel axes in the envelope, a grid associated with each of said electrodes, a pair of leads sealed to thmenvelope and extending transversely of said axes, means supporting the grids on said pair of leads, another lead sealed to the envelope, and means supporting the plate electrodes on the last mentioned lead.

11. An electronic tube comprising an envelope, a pair of plate electrodes disposed about substantlally parallel axes in the envelope, a grid associated with each of said electrodes, 8. pair of leads sealed to the envelope and extending transversely of said axes, means supporting the grids on said pair of leads, a second pair of leads extending transversely of said axes, and means supporting the plate electrodes on the last mentioned pair of leads.

12. An electronic tube comprising an envelope,

a pair of plate electrodes disposed about substantially parallel axes in the envelope, a grid associated with each of said electrodes and having a free end and a terminal end, a pair 01' leads extending transversely of said axes and sealed to the envelope, means tying the terminal ends of the grids together and supporting them on said pair of leads, a secondpair 01 leads extending transversely of said axes and sealed to the envelope, and means supporting the plate electrodes on the last mentioned pair of leads.

13. An electronic tube comprising an envelope, a pair of plate electrodes disposed about substantially parallel axes in the envelope, 9. grid associated with each of said electrodes, a pair of aligned leads sealed to the envelope and extending transversely of said axes, means supporting the grids on the opposing inner ends of said leads, a second pair of aligned leads sealed to the envelope and extending transversely oi said axes, and means supporting the plate electrodes on the opposing inner ends oithe last mentioned pair of leads.

14. An electronic tube comprising an envelope, an electrode in the envelope, a lead sealed to the envelope, and a hollow bracket with a conical surface having its diverging end secured to the electrode and its converging end secured to the inner end of the lead.

15. An electronic tube comprising an envelope, a plurality of grids in the envelope, a ring at an end oi each grid, means connecting said rings together, conductor means extending through the envelope, and means adjacent the connected ends of the grids supporting them on said conductor means.

16. An electronic tube comprising an envelope, a plurality 01' plate electrodes disposed about substantially parallel axes in the envelope, 0. grid associated with each of said electrodes and having a free end and a terminal end, conductor means extending through the envelope along a line disposed longitudinally of said axes, means tying the plate electrodes together and supporting them on said conductor means, conductor means extending through the envelope along a line disposed transversely of said axes, and means tying the terminal ends of the grids together and supporting them on the last mentioned conductor means.

1'7. An electronic tube comprising an envelope, a pair of cathodes in the envelope and each having a pair 01 downwardly extending filament sections, a pair of standards projecting into the envelope and each connected to the upper ends oi. a pair or said filament sections, a connector secured to the lower end or a filament section in each pair, a second connector secured to the lower end of another filament section in each pair, and a. pair of leads projecting into the envelope and each secured to one of said connectors.

18. An electronic tube comprising an envelope, a tubular plate electrode in the envelope, at cathode comprising a pair of helical filament sections coaxial with said plate electrode, a standard projecting into the envelope from the lower portion thereof and connected to the upper ends or the filament sections, a air of leads projecting into the envelope from said lower portion and connected to the lower ends 01' the filament sections, and conductor means for the plate electrode projecting into the upper end portion 01' the envelope.

WILLIAM W. EI'IEI...

JACK A. McCULlDUGH.

DISCLAIMER Patent dated Ma McCullough, San Bruno, Calif. THERE- 14, 1946. Disclaimer filed Dec. 20,

ough, Inc.

Hereby enters this disclaimer to claim l8 of said patent.

l flitial Gazette January 21, 1947.]