US3505552A - High power,light weight electron tube - Google Patents

Description

April 7, 1970 J. w. HAGOO D ETAL HIGHYPOWER, LIGHT WEIGHT ELECTRON TUBE Filed Sept. 15, 1957 Jerr W Ho ood Joe Shelton I M M mviszqroxs. BY fly 1 United States Patent HIGH POWER, LIGHT WEIGHT ELECTRON TUBE Jerry W. Hagood and Joe Shelton, Huntsville, Ala., as-

signors to the United States of America as represented by the Secretary of the Army Filed Sept. 15, 1967, Ser. No. 668,244 Int. Cl. H01j' 29/02 US. Cl. 313-89 7 Claims ABSTRACT OF THE DISCLOSURE An electron tube is used with a high temperature radiator to provide a system of reduced weight for operation in the exo-atmosphere. A collector is adapted to be released and ejected partially or completely when the desired minimum altitude has been attained. A ring similar to the accelerating anode and operating near the same potential may be located near the collector to accelerate an electron beam toward the radiator after the collector has been discarded.

DEDICATORY CLAUSE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

BACKGROUND OF THE INVENTION It is desirable to have high power electron tubes for operation at high altitudes. One of the major problems associated with high power electron tubes operating at high altitudes is the weight of the tube. This weight consists primarily of a heat sink to absorb the heat generated by the tubes electron beam. Since electrons, when striking a collector, dissipate a significant portion of their energy as heat, the heat sink size and weight and that of auxiliary cooling equipment for a high power tube may be prohibitive for outer-atmospheric vehicles.

SUMMARY OF THE INVENTION The present invention is a high power, light weight electron tube that requires no heat sink when operated at altitudes above about 160 kilometers. The collector is one of very modest weight, on the order of a few pounds, and the tube can be fabricated using conventional techniques. The radio frequency input and output connections to the tube, which are normally sealed by a window that is transparent to microwave energy, need no longer be sealed when exo-atmospheric altitudes are attained. The heat sinks normally associated with these windows are no longer necessary and unwanted standing wave ratios magnified by sealed windows will be reduced when the discontinuity of the seal is removed thereby increasing the overall tube efficiency.

An object of this invention is to provide a novel highpower tube.

Another object is to provide a traveling wave tube having a disposable collector and a heat radiator located remotely from the traveling wave tube to collect the electron beam when the disposable collector is removed.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a traveling wave tube with a voltage gradient collector having a removable end plug.

FIGURE 2 is a section of a traveling wave tube showing a constant voltage collector in the process of being jettisoned.

FIGURE 3 is a section of a traveling wave tube showing the mating edges of the collector shown in FIGURE 2 with the tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of be high power light weight electron tube, as shown in FIGURE 1, consists of a housing assembly 10 containing conventional traveling wave tube elements, or other linear beam device, that requires no heat sink when operated at altitudes above about kilometers. The electron beam is formed in the usual manner except for a minor change in the cathode. Typically, an electron gun produces a beam of electrons which is shot through a long helix and collected by an electrode at anode potential. The collecter 12 consists of a series of individually insulated collectors maintained at separate voltage levels, with each voltage level (progressing in the direction of electron beam flow) lower than the preceding level. Therefore, the potential V is the highest collector potential and V is the lowest collector potential. As the electrons move through the decreasing potential in the segmented collector 12, the low energy electrons are collected near the entrance and the higher energy electrons are collected toward the end of the collector. Since the electrons lose energy as they move through the decreasing field, they are collected with a minimum kinetic energy which in turn generates a minimum amount of heat at the collector. A removable end cover 14 in the end of this segmented collector depends only on the pressure differential for removal, and would be applicable for tubes that were to be activated after the desired altitude is reached. The altitude at which the end cover is ejected depends on the degree of vacuum within the tube. When the tube is placed in an outer-atmosphere condition, outside pressure will decrease until the inside pressure is greater than the outside pressure and the cover will be forced off. This method works equally well for the segmented collector 12 or a tube with an accelerating ring, which will be considered later.

The gun structure is fabricated in the usual manner except that a slightly more active cathode is used to insure emission at pressures of about 10- millimeters of mercn'ry. These are readily available from commercial suppliers. A more active cathode also allows the tube to reactivate itself in the event that a leak develops while the tube is in storage. Since the environmental conditions at high altitudes act as an unlimited vacuum pump, any gas evolved during operation of the tube will be immediately ejected without degrading tube performance. This fact may permit the use of lighter weight materials in the tube construction, resulting in a system weight reduction.

When the inside pressure forces cover 14 from collector 12, the electrons are allowed to exit through the open end of the tube and are collected on a heat radiator 16 operating at a voltage V that is near the same potential as the collector. Radiator 16 is aligned with its face perpendicular to and centered around the center line of the tube.

A second embodiment of the light weight electron tube, as shown in FIGURE 2, may be constructed with the collector omitted altogether or replaced by a ring similar to the accelerating anode and operating near the same potential. In order to properly activate and store the tube, a temporary end is placed over the tube, and is removed after the tube reaches a predetermined altitude or pressure. After the temporary end is moved, the tube when activated will generate an electron beam to be collected on the external heat radiator 16. An accelerating ring will serve to direct the beam over a broad area of the radiator, which will facilitate cooling the area.

FIGURE 2 shows a method for attaching a temporary plate 20 to tube 10. This adaptation is applicable for all types of linear beam tubes. It is applicable for tubes with a segmented collector, a plain collector, or with only a collector ring. A removable collector may be attached in like manner. The end plate assembly, as well as being designed for use on all types of linear beam tubes, is designed such that the tube can be activated and tested prior to actual operation. The end plate is always in electrical contact with the tube element preceding it, thus it will act as either a part of or the entire collector, depending on tube design.

The assembly is bolted together with the four springs 22 compressed, and is sealed by a thin foil 24 (shown in FIGURE 3) that is brazed or welded to the end plate 20 and a collector ring 26. Explosive bolts 28 are used to attach a metal cover plate 30 to tube 10. End plate 20' is attached to cover plate 30 by an insulating ring 32. The explosive bolts can be triggered by a pressure switch, a timing device, or other means. When bolts 28 are released, springs 22 exert sufiicient force to rupture the thin foil sealing strip 24 and eject end plate 20. The electron beam will then be directed to radiator 16.

We claim:

1. An electron tube comprising: a housing assembly; a collector assembly; means connecting said collector to said housing, wherein said connecting means includes a preset release mechanism for removing at least a section of said collector; and an external heat radiator co-axially aligned with and adjacent to said collector assembly to attract electron flow when said collector section is removed.

2. The electron tube is set forth in claim 1 wherein the collector assembly includes a segmented collector composed of a series of collectors insulated from each other and maintained at separate incremental voltage levels.

3. The electron tube as set forth in claim 2 wherein said segmented collectorhas a removable end plate held in place by pressure external to the tube.

4. The electron tube as set forth in claim 1 wherein said collector assembly includes a collector ring permanently attached to but insulated from said housing assembly and a removable end plate covering said collector ring.

5. The electron tube as set forth in claim 4 wherein said connecting means is attached to the removable end plate and wherein said connecting means includes a cover plate with attached explosive bolts for removing said coverplate from the tube.

6. The electron tube as set forth in claim 4 wherein a thin metal foil forms a seal between said collector ring and said removable end plate.

7. The electron tube as set forth in claim 6 wherein said connecting means is attached to the end plate, and includes a coverplate attached to said housing assembly so as to be easily detached.

References Cited UNITED STATES PATENTS 3,175,120 3/1968 Wendt 3155.38 3,368,104 2/1968 McCullough 3155.38 3,414,757 12/1968 Levin ct al. 315-538 HERMAN KARL SAALBACH, Primary Examiner S. CHATMON, JR., Assistant Examiner US. Cl. X.R.

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