This disclosure is directed generally to heating systems. More specifically, this disclosure relates to a four-braid resistive heater and devices incorporating such a resistive heater.
Various types of devices use temperature control mechanisms to stabilize or adjust the temperatures of components in those devices. For example, thermal stabilization is often used in devices that contain long optical fibers and in devices that depend upon optical transitions of atoms or molecules. Unfortunately, various types of devices may also need magnetic shielding in order to block ambient magnetic fields or other magnetic fields. Thermal stabilization and magnetic shielding requirements often work in opposition to each other because electrical heaters typically generate strong magnetic fields. As a result, it can be difficult to provide electrical heaters that provide adequate heating to thermally stabilize components of a device without also generating excessive magnetic fields that interfere with operations of the device.
This disclosure provides a four-braid resistive heater and devices incorporating such a resistive heater.
In a first embodiment, an apparatus includes a four-braid resistive heater, which includes a conductive structure configured to transport electrical currents and to generate heat based on the electrical currents. The conductive structure has first, second, third, and fourth electrical conductors. The first and second electrical conductors are looped around each other along a length of the conductive structure. The third and fourth electrical conductors are looped around each other along the length of the conductive structure. Loops formed with the first and second conductors are interleaved with loops formed with the third and fourth conductors along the length of the conductive structure.
In a second embodiment, a system includes a heated component and a heating element configured to heat the heated component. The heating element includes a four-braid resistive heater, which includes a conductive structure configured to transport electrical currents and to generate heat based on the electrical currents. The conductive structure has first, second, third, and fourth electrical conductors. The first and second electrical conductors are looped around each other along a length of the conductive structure. The third and fourth electrical conductors are looped around each other along the length of the conductive structure. Loops formed with the first and second conductors are interleaved with loops formed with the third and fourth conductors along the length of the conductive structure.
In a third embodiment, a method includes transporting electrical currents through a four-braid resistive heater having a conductive structure and generating heat using the conductive structure based on the electrical currents. The conductive structure has first, second, third, and fourth electrical conductors. The first and second electrical conductors are looped around each other along a length of the conductive structure. The third and fourth electrical conductors are looped around each other along the length of the conductive structure. Loops formed with the first and second conductors are interleaved with loops formed with the third and fourth conductors along the length of the conductive structure.
Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
The conductive structure 104 here includes four electrical conductors 106-112. Each electrical conductor 106-112 represents an elongated resistive conductive path through which an electrical current can flow, thereby generating heat. Each electrical conductor 106-112 could be formed from any suitable material(s), such as one or more metals. Also, each electrical conductor 106-112 could have any suitable length. In addition, each electrical conductor 106-112 could have any suitable form factor, such as a solid-core wire or multi-strand wire.
In this example, the electrical conductors 106-112 are arranged in a four-braid arrangement. That is, the four electrical conductors 106-112 loop around each other down the length of the conductive structure 104. In this example, two electrical conductors 106-108 form a first twisted pair since the conductors 106-108 generally loop around each other down the length of the conductive structure 104. Similarly, two electrical conductors 110-112 form a second twisted pair since the conductors 110-112 generally loop around each other down the length of the conductive structure 104. Moreover, the electrical conductors 106-108 in the first twisted pair periodically (or otherwise) loop around the electrical conductors 110-112 of the second twisted pair, and the electrical conductors 110-112 in the second twisted pair periodically (or otherwise) loop around the electrical conductors 106-108 of the first twisted pair. This creates a structure in which the four electrical conductors 106-112 are generally braided together into a single overall structure.
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In this arrangement, electrical currents flow from the power supply 102 through the electrical conductors 106-108, and the electrical currents return to the power supply 102 through the electrical conductors 110-112. Since the electrical conductors 106-112 are resistive structures, the electrical currents generate heat, which can be used to set or adjust the temperature of a device or system (or portions thereof).
The magnetic fields generated using a four-braid arrangement can be significantly smaller than the magnetic fields generated using other arrangements of electrical conductors. This allows thermal stabilization or thermal management to occur with fewer complications associated with electrical heating. In fact, a four-braid arrangement could represent an optimal or near-optimal solution for reducing magnetic fields from conductive wires and by design can reduce or eliminate higher-order terms. All of this can be accomplished using a low-cost device with a small form factor.
This functionality can find use in a wide variety of structures. For example, a four-braid resistive heater 100 could be used to heat an atomic reference cell of a photonic oscillator without generating Zeman splitting of the resonances. A four-braid resistive heater 100 could also be used to thermally stabilize a fiber optic coil without causing Verdet rotation of polarization within the coil. A four-braid resistive heater 100 could further be used to heat or thermally stabilize electronic circuitry or other object(s) without significantly inducing magnetic fields in the object(s). These represent examples of the different ways in which one or more four-braid resistive heaters 100 could be used. One or more four-braid resistive heaters 100 could be connected in series, in parallel, or in series and in parallel and used in any other suitable manner.
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The conductive vias 210 in each layer 206a-206d represent conductive paths through that layer. In other words, each conductive via 210 in a layer 206a-206d represents a path over which an electrical connection can be formed through the insulative dielectric 208 in that layer. Each conductive via 210 includes any suitable conductive material(s), such as metal. The same conductive material(s) can be used in each conductive via 210, or different conductive material(s) can be used in different conductive vias 210. The conductive vias 210 in each layer 206a-206d can also be formed in any suitable manner, such as by depositing and etching a metal layer (followed by deposition of the dielectric 208) or by etching holes in the dielectric 208 and depositing conductive material into the holes.
The resistive paths 212 in each layer 206a-206d represent conductive paths connecting multiple vias 210 of that layer. Each resistive path 212 includes any suitable conductive material(s), such as metal. The same conductive material(s) can be used in each resistive path 212, or different conductive material(s) can be used in different resistive paths 212. The resistive paths 212 in each layer 206a-206d can also be formed in any suitable manner, such as by depositing and etching a metal layer.
As shown in this example, the conductive vias 210 in each layer 206a-206d are generally aligned, meaning the conductive via 210 at one location of one layer is electrically connected to conductive vias 210 at substantially the same locations in other layers. The vias 210 at substantially the same locations in the layers 206a-206d therefore form an electrical path through the conductive structure 204.
Moreover, the vias 210 and resistive paths 212 in the layers 206a-206d collectively form four different electrical conductors (the electrical conductors 106-112 of
Similarly, the electrical conductors 110-112 are implemented in the layers 206b and 206d. One conductor 110 starts where the fourth row, first column via 210 in layer 206b connects to the power supply 202. The other conductor 112 starts where the second row, first column via 210 in layer 206d connects to the power supply 202. These two conductors 110-112 then loop around each other as their respective electrical paths move between and across the layers 206b and 206d.
Since the conductors 106-108 travel between layers 206a and 206c and the conductors 110-112 travel between layers 206b and 206d, the conductors 106-108 loop around the conductors 110-112. This forms a four-braid structure, which is implemented using substantially horizontal and vertical components. This can help to facilitate simpler or more cost-effective fabrication of a four-braid resistive heater.
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A line 304 is associated with a resistive heater having two wire conductors, where the two wire conductors are arranged as a perfect twisted-pair. A line 306 is associated with a resistive heater having six wire conductors, where the six wire conductors have a perfect hexapole arrangement. As can be seen here, the twisted-pair and hexapole resistive heaters do provide significant magnetic field attenuation compared to a single-wire conductor. Moreover, for wire gauges above an American Wire Gauge (AWG) value of about five or six, the twisted-pair and hexapole resistive heaters have very similar attenuations. A line 308 is associated with a resistive heater having eight wire conductors, where the eight wire conductors have a perfect octopole arrangement. As can be seen here, the octopole resistive heater again provides significant magnetic field attenuation compared to a single-wire conductor and better magnetic field attenuation than the twisted-pair and hexapole resistive heaters for wire gauges above an AWG value of about five or six.
In light of this, one might expect that the behavior of a resistive heater with a four-braid arrangement would lie along the same general line as the resistive heaters with the twisted-pair and hexapole arrangements. However, a resistive heater with a four-braid arrangement actually provides significant improvement over the twisted-pair, hexapole, and octopole arrangements. As shown in
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One or more four-braid resistive heaters can be used in any of the photonic oscillators described above (or other photonic oscillators). For example,
In this example, at least one four-braid resistive heater 508 could be used in at least one window 504 of the gas cell 500. Also, at least one four-braid resistive heater 510 could be used in at least one wall of the gas cell 500, and/or at least one four-braid resistive heater 512 could be used across the at least one wall of the gas cell 500 (where the at least one wall helps to define the cavity 502). Further, at least one four-braid resistive heater 514 could be used in the fill tube 506 of the gas cell 500. In addition, at least one four-braid resistive heater 516 could be used in a housing 518 that encases or otherwise surrounds the gas cell 500. Note that these represent examples of the ways in which a four-braid resistive heater can be used in a photonic oscillator, and one or more four-braid resistive heaters could be used in a photonic oscillator in other or additional ways.
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Electrical current is generated through the conductors at step 806. This generates heat at step 808, which can be used to heat a device or system at step 810. This could include, for example, generating electrical currents through the conductors 106-108, which are coupled respectively to conductors 110-112. The electrical currents through the conductors 106-108 therefore also travel through the conductors 110-112. The heat here could be used to thermally control any suitable device or system, such as a photonic oscillator, optical gyroscope or other component having an optical fiber, or electrical/optical circuit.
Assuming the process continues at step 812, the process returns to step 806. Otherwise, the generation of electrical current (and therefore heat) can terminate, and steps 806-812 can resume later if necessary to continue the thermal management of the device or system.
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It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.
While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.