Patent Grant
11894208
The present disclosure relates generally to a manufacturing process used for the fabrication of vacuum electron devices (VEDs) having a plurality of two-dimensional layers of various materials that are bonded together to form one or more VEDs simultaneously. The two-dimensional material layers are machined to include features needed for device operation so that when assembled and bonded into a three-dimensional structure, three-dimensional features are formed. The two-dimensional layers are bonded together into a sandwich-like structure. The manufacturing process enables incorporation of metallic, magnetic, ceramic materials, and other materials required for VED fabrication while maintaining required positional accuracy and multiple devices per batch capability.
Vacuum electron devices (VEDs) operate in a vacuum environment and take advantage of the interaction between one or more electron beam(s) and an electromagnetic field generated in an interaction region of the VED. The construction of a VED requires incorporation of metallic, ceramic, magnetic and other materials into a single assembly which may be held at or enclosed in a vacuum so as not to impede the transit of electrons from a cathode (electron emitter) to a collector (electron receptor) of the vacuum electron device. The vacuum region is also referred to as a vacuum chamber or cavity or tunnel (electron beam tunnel) or RF interaction region and is where the interaction between the electron beam(s) and the electromagnetic wave(s) takes place. Examples of such VEDs in the prior art include (but are not limited to) particle accelerators, klystrons, gyrotrons, gyro-klystrons, gyro-amplifiers, travelling wave tubes (TWTs), gyro-TWTs, backward wave oscillators, inductive output tubes (IOTs), magnetrons, cross-field amplifiers, free electron lasers, ubitrons, masers, diodes, triodes, tetrodes, pentodes, and the like. Some gas ion lasers, while not strictly operating at a vacuum but at a very low pressure, and generally lacking an RF interaction region, operate in much the same manner.
Prior VEDs were generally manufactured using individual two- and three-dimensional subcomponents, forming the subcomponents into an assembly, bonding the assembly to an envelope to provide a structural support and a vacuum envelope, and then carrying out conventional vacuum processing and sealing procedures to yield a functioning VED. Such procedures could take, depending upon the complexity of the device, weeks or more to complete a single device and utilized a great deal of highly skilled hands-on labor and large clean rooms in which to carry out the procedures. Today, as wireless high bandwidth data communications demand is exploding from earth stations to satellites to cell towers and local WIFI systems and ground backbone systems, a substantial need exists for large quantities of such devices at lower cost.
The subject matter described herein generally relates to the manufacturing of vacuum electron devices (VEDs) utilizing parallel sheets of materials which are assembled in a stack and bonded together to form a three-dimensional VED. An advantage of this approach is that a plurality of VEDs may be manufactured simultaneously in the same structure and simply cut apart when complete for individual use much like is commonly done in semiconductor device fabrication, thus reducing the per-device manufacturing cost significantly.
The foregoing overview is a summary and thus may contain simplifications, generalizations, and omissions of detail; consequently, those skilled in the art will appreciate that the overview is illustrative only and is not intended to be in any way limiting.
The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more exemplary embodiments and, together with the description of the exemplary embodiments, serve to explain the principles and implementations of the invention.
In the drawings:
Exemplary embodiments are described herein in the context of a VED such as a TWT (commonly used for RF signal amplification in high-bandwidth data communications systems). Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. Other embodiments will readily suggest themselves to such skilled persons having the benefit of this disclosure. Reference will now be made in detail to implementations of the exemplary embodiments as illustrated in the accompanying drawings. The same reference indicators will be used to the extent possible throughout the drawings and the following description to refer to the same or like items.
In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.
References herein to “one embodiment” or “an embodiment” or “one implementation” or “an implementation” and the like means that a particular feature, structure, part, function or characteristic described in connection with an exemplary embodiment can be included in at least one exemplary embodiment. The appearances of phrases such as “in one embodiment” or “in one implementation” and the like in different places within this specification are not necessarily all referring to the same embodiment or implementation, nor are separate and alternative embodiments necessarily mutually exclusive of other embodiments.
In accordance with this disclosure, the components and process steps described herein may be implemented using various techniques without departing from the scope and spirit of the inventive concepts disclosed herein.
What is described here includes examples of the embodiments of the present invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but it is to be appreciated that many further combinations and permutations of the subject innovation are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims. Moreover, the above description of illustrated embodiments of the subject disclosure, including what is described in the Abstract, is not intended to be exhaustive or to limit the disclosed embodiments to the precise forms disclosed. While specific embodiments, examples and implementations are described herein for illustrative purposes, various modifications are possible that are considered within the scope of such embodiments and examples, as those skilled in the relevant art can recognize.
In particular and in regard to the various functions performed by the above described components, devices, systems and the like, the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., a functional equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary aspects of the claimed subject matter.
In addition, while a particular feature of the subject invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “includes,” “including,” “has,” “contains,” variants thereof, and other similar words are used in either the detailed description or the claims, these terms are intended to be inclusive in a manner similar to the term “comprising” as an open transition word without precluding any additional or other elements.
Moreover, the words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.
In the figures, where a callout number or reference symbol is used in more than one figure, it is intended to refer to the same or a similar part, component or step, unless clearly not so intended from the contents of the disclosure.
The devices and methods described herein can be employed for VEDs utilizing pencil beams, sheet beams, rectangular beams, elliptical beams, hollow beams, distributed beams and multiple beams.
While most of the description below is addressed to building a VED in layers from below the electron beam to above the electron beam with plates arrayed parallel to the electron beam, it is also contemplated that such a device may be constructed orthogonal to the electron beam in a relatively straightforward manner given the teachings herein. Such a device may also be constructed at an arbitrary angle to the electron beam if desired, as, for example, in a distributed beam device.
A key benefit of the present invention is its ability to permit the simultaneous fabrication of a plurality of VEDs in one batch and then cut them into individual components, although using this invention to make even single prototype devices has proven to be much more cost effective than prior technologies.
Typically, magnets are used to provide at least some of the electron beam forming and aiming functions in a VED. If the electron beam is not properly directed from the cathode to the collector it may impinge upon some other part of the VED structure, causing damage and contaminating the vacuum area. The ability to incorporate a variety of magnet material types is beneficial to the assembly of VEDs. Hallbach, or quadrupole arrays are often employed for focusing the electron beam as are solenoids deployed about the electron beam at some distance from it. Another key benefit of the present invention is its ability to provide a higher strength magnetic field at the electron beam for a given magnet (electromagnetic solenoid or fixed) because the invention allows the magnets to be brought much closer to the electron beam without placing them within the vacuum chamber. Since the magnetic field from a magnet decreases with the square of the distance from the magnet the magnets may be brought closer and thus made smaller by means of the present invention. The magnetic steering can be performed by means of actual magnets as well as a combination of magnets and magnetically susceptible materials which, in conjunction with the magnets, establish desired magnetic fields within the VED to properly steer the electron beam. Since magnetic materials and/or iron- and nickel-containing materials are not good electrical conductors, the electromagnetic circuit is typically made of materials like copper (or tungsten for helix-type devices) moving the focusing structure further from the electron beam. The magnets and/or iron- and nickel-containing materials can be electroplated with high electrical conductivity materials such as copper and employed to alleviate this problem, however such an arrangement can create potential vacuum purity issues for the VED as such materials can degrade over time in a VED. It is possible to use vacuum double-melted iron with high quality nickel plating inside the vacuum envelope. Permanent magnetic materials such as SmCo and NbFeB in most cases would have to be added outside the vacuum envelope (because heating a permanent magnet above its Curie point will cause it to lose its magnetism) and low temperature bonding techniques used (adhesives or solid state ultrasonic) to secure such materials in place.
In one embodiment, magnets may be added to the circuits of the present invention as follows. To join the copper sheets to create a TWT circuit (for example) each sheet will be sputter coated with a few-hundred nanometer thick gold or silver layer and then bonded to an adjacent layer in a hydrogen furnace at around 1000 degrees centigrade with about a 50-pound weight or in a fixture to secure the layers in place. To add a magnetic assembly to the layered copper circuit assembly, the iron (vacuum double-melted) or stainless-steel layer(s) will be nickel plated with pockets for magnet pieces and copper-gold or copper-silver braze shims (about 25 microns thick) may be used for creating a braze joint. The iron/stainless steel layers will then be brazed to the copper circuit assembly, but remain outside the vacuum region of the VED, by melting the braze shim. Magnet pieces will then be inserted into the premade pockets in the assembly and another material layer will be added over the magnets and secured using low temperature adhesives to hold the magnets in place.
Electrostatic focusing may also be used to provide some of the electron beam forming and aiming functions in a VED. The ability of the present invention to introduce electrical conductors into the vacuum structure now permits the use of precise electrostatic focusing within the vacuum structure by applying a voltage across two or more plates disposed about the electron beam. A number of sets of such plates may be employed if desired or required by the specific application.
The manufacturing approach described herein can be employed for manufacturing VEDs at a variety of frequencies, but it is especially beneficial for VEDs operating between about 25 GHz and about 1 THz. The manufacture of such devices using conventional manual device assembly is challenging due to the small feature scale (micrometers to millimeters in some cases).
Turning now to the figures,
In the embodiment illustrated in
Where desired, an electrically conductive plate may be coated on one or both sides with a vacuum-appropriate insulator, such as sputtered alumina (Al2O3) or another convenient insulator that will not outgas into a vacuum environment heated by the presence of an electron beam in order to build more complex circuits.
In the embodiment illustrated in
In the embodiment of
In the embodiment illustrated in
In the embodiment illustrated in
The gap 802 may be cut, diced, machined, punched or otherwise created in any conventional manner suitable for the cutting of such materials, e.g., laser, high-pressure water, diamond-bladed saw, and the like. Once the gap 802 is formed, the individual VEDs 806 may be removed and individually packaged for use in a conventional manner as would be known to those of ordinary skill in the art.
At block 1002 is a first step: forming a first planar non-magnetic conductor plate from a non-magnetic electrically conductive material.
At block 1004 is a second step: forming a second planar non-magnetic conductor plate from a non-magnetic electrically conductive material.
At block 1006 is a third step: forming an interaction structure from a plurality of electrically conductive non-magnetic interaction structure forming plates arranged in parallel with one another with portions of interaction zones cut into the respective electrically conductive non-magnetic interaction structure forming plates.
At block 1008 is a fourth step: disposing the first planar non-magnetic conductor plate, the interaction structure, and the second planar non-magnetic conductor plate in a stack such that the first planar non-magnetic conductor plate and the second planar non-magnetic conductor plate are on the outside of the stack.
At block 1010 is a fifth step: bonding the first planar non-magnetic conductor plate, the interaction structure, and the second planar non-magnetic conductor plate together.
At block 1012 is a sixth step: forming a first planar magnetic plate from a magnetic material and disposing at least one magnet on it.
At block 1014 is a seventh step: disposing the first planar magnetic plate parallel to the first planar non-magnetic conductor plate on a side of the first planar non-magnetic conductor plate opposite the plurality of non-magnetic interaction structure forming plates.
At block 1016 is an eighth step: bonding the first planar magnetic plate to the first planar non-magnetic conductor plate.
At block 1018 is a ninth step: forming a second planar magnetic plate from a magnetic material and disposing at least one magnet on it.
At block 1020 is a tenth step: disposing the second planar magnetic plate parallel to the second planar non-magnetic conductor plate on a side of the second planar non-magnetic conductor plate opposite the plurality of non-magnetic interaction structure forming plates.
At block 1022 is an eleventh step: bonding the second planar magnetic plate to the second planar non-magnetic conductor plate.
Those of ordinary skill in the art will now realize that these steps can be performed in an order most convenient for manufacture and need not be carried out in lock step. For example: the bonding steps could all be carried out at one time; the forming steps can be carried out in advance to fabricate parts for later assembly; and the like.
In bonding the two-dimensional sheets together, the following processes may be used: brazing, diffusion bonding, assisted diffusion bonding, solid state bonding, cold welding, ultrasonic welding, a combination of one or more of the foregoing, and the like. The joint formed between two adjacent sheets should maintain a vacuum environment of better than 1×10−6 Torr. The bonding should be carried out in a non-reactive environment such as: hydrogen, nitrogen, vacuum and the like. Prior to bonding, the respective layers should be cleaned or plasma etched to remove the surface oxide layer and maintained in a vacuum environment prior to bonding in order to assist the formation of a good leak-tight bond. Where needed, the respective layers may be coated (sputtered, electroplated, metallized and/or painted) with vacuum-compatible materials that enhance the creation of a vacuum compatible interface between the two respective layers (which may be dissimilar materials). The coatings may include one or more of: nickel, gold, silver, molybdenum-manganese, copper, copper-gold, copper-silver, titanium-nickel, gold-copper-titanium, copper-silver-titanium, copper-silver-titanium-aluminum, titanium-nickel-copper, gold-copper-titanium-aluminum, silver-copper-indium-titanium, copper-germanium, palladium-nickel-copper-silver, gold-palladium-manganese, silver-palladium, gold-copper-nickel, gold-copper-indium, silver-copper-indium, gold-nickel, gold-nickel-chromium, and the like. In this manner the bonded layers form a high-strength assembly resulting in relatively high-power handling capability and high gradient capability VEDs.
The layers may be coated as well (sputtered, electroplated, metallized and/or painted) with electrically insulating or electrically conductive materials to manage voltage potentials in the VED as well as heat flow. Coatings may also include materials designed to conduct heat (e.g., diamond films, diamond conduction channels, cooling channels, heat pipes, and the like) in order to better manage heat flow within and away from the VED. Layers may be fabricated of insulators (e.g., Al2O3) which are then plated with conductive paths in order to form electrodes and electrical paths with which to bias the electrodes.
Cutouts or pockets may be formed in the electrically conductive sheets of the VED using techniques such as milling, turning, electric discharge milling, lithography, etching, laser cutting, electron beam cutting, waterjet cutting, and the like. Cutouts and pockets so formed may be populated by such components as ceramic materials, vacuum windows, circuit sever materials (attenuators used to improve device stability), electron emissive materials, vacuum pumping materials, getter materials, magnets, iron pieces, shielding materials, isolating materials, conductor wires, connectors, wave guides, couplers and the like.
The incorporation of ceramic materials enables the addition of electrostatic beam forming lenses or areas within the VED to aid in focusing, propagating, guiding, steering, and ultimately improving electron beam propagation between the cathode and the collector. By building this capability into the VED itself, rather than providing it outside of the vacuum region of the VED, finer and lower-power consuming control of the electron beam is made possible.
The alignment of adjacent layers or sheets of materials with in the VED during the manufacturing process may be accomplished using alignment features 112. Such features may be alignment holes, alignment pins, rectangular features, combinations thereof, optical (visible) marks suitable for robotic assembly techniques, as discussed elsewhere herein, and the like. The assembly of the sheets may be effected by manual assembly, robotic assembly, translational stages, automatic translation, robotic placement, micro to nanoscale video alignment, vernier scales, and the like.
It is to be noted that the foregoing approach permits the construction of a VED without magnets altogether and using purely electrostatic focusing.
While exemplary embodiments and applications have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that numerous modifications, variations and adaptations not specifically mentioned above may be made to the various exemplary embodiments described herein without departing from the scope of the invention which is defined by the appended claims.
The present application claims the benefit of priority based on: (1) U.S. Provisional Patent Application Ser. No. 63/198,817, filed on Nov. 15, 2020, in the name of inventor Diana Gamzina Daugherty and commonly owned herewith, entitled “Multi-layered multi-material manufacturing process for vacuum electronic devices”, the contents of which are hereby incorporated by reference as if set forth fully herein; and (2) U.S. Provisional Patent Application Ser. No. 63/198,915, filed on Nov. 21, 2020, in the name of inventor Diana Gamzina Daugherty and commonly owned herewith, entitled “Electronic magneto-electrostatic sensing, focusing, and steering of electron beams in microwave, millimeter wave, and near-terahertz vacuum electronic devices”, the contents of which are hereby incorporated by reference as if set forth fully herein. The present application may be considered related to another patent application: U.S. patent application Ser. No. 17/525,698, filed on Nov. 12, 2021, and entitled “Magneto-Electrostatic Sensing, Focusing, and Steering of Electron Beams in Vacuum Electron Devices”, in the name of inventor Diana Gamzina Daugherty and commonly owned herewith, which, in turn, claims the benefit of priority based on: (1) U.S. Provisional Patent Application Ser. No. 63/198,817, filed on Nov. 15, 2020, in the name of inventor Diana Gamzina Daugherty and commonly owned herewith, entitled “Multi-layered multi-material manufacturing process for vacuum electronic devices”; and (2) U.S. Provisional Patent Application Ser. No. 63/198,915, filed on Nov. 21, 2020, in the name of inventor Diana Gamzina Daugherty and commonly owned herewith, entitled “Electronic magneto-electrostatic sensing, focusing, and steering of electron beams in microwave, millimeter wave, and near-terahertz vacuum electronic devices”. The contents of U.S. patent application Ser. No. 17/525,698 are hereby incorporated by reference as if set forth fully herein.
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