Patent Application
20160040830
The present disclosure relates generally to cryogenic superconductor assemblies, and more specifically, to electrical interconnects configured to route electrical signals to cryogenic assemblies.
Cryogenic assemblies are being pursued to house superconducting components and circuitry. When placed in cryogenic conditions, superconducting circuits and components provide a significant performance increase (e.g., approximately 10×-20×) compared to conventional semiconductor components. Cryogenic temperatures within the cryogenic assembly must be sustained to achieve the performance increase.
An example of a conventional cryogenic assembly 10 is illustrated in
One of the largest contributors of parasitic heat flux intrusion into the vacuum assembly 14 is the electrical connector 22 that carries electrical signals such as for example, power and control signals, to the electronics mounted inside the vacuum assembly (i.e., the dewar). One or more wires 24 of the connector 22, however, are thermally conductive and typically emit heat (T1) when delivering the power and/or electrical signals. Consequently, parasitic heat flux is allowed to enter into the vacuum assembly 14 via the wires 24. Therefore, the power consumption and work output of the cryocooler 12 increases as parasitic heat flux into the vacuum assembly 14 increases.
According to an embodiment, cryogenic heat flow reduction assembly comprises a platform configured to support at least one electronic component, and a housing that defines a cavity in which the platform is disposed. The housing is configured to thermally insulate the cavity from surrounding ambient air such that the cavity is maintained at a cryogenic temperature. The cryogenic heat flow reduction assembly further includes at least one connector configured to deliver an electrical signal from a source external to the housing. The at least one connector includes at least one carbon nanotube interconnect that inhibits heat flow into the cavity while delivering the electrical signal.
According to another embodiment, a connector comprises at least one conductive element including a first end configured to receive an electrical signal and a second end configured to output the electrical signal to a cryogenic assembly. The connector further includes at least one carbon nanotube interconnect interposed between the first end and the second end. At least one carbon nanotube interconnect is configured to inhibit heat flow to the second end while maintaining electrical conductivity between the first end and the second end.
According to yet another embodiment, a method of improving power efficiency of a cryogenic assembly comprises outputting an electrical signal to a first portion of an electrical connector. The electrical signal induces a heat flow through the first portion of the electrical connector. The method further includes inhibiting the heat flow from flowing to a second portion of the electrical connector, where the portion of the electrical connector exists at a cryogenic temperature. The method further includes delivering the electrical signal to the second portion of the electrical connector. The second portion is electrically connected to the cryogenic assembly such that the power efficiency is improved.
Additional features are realized through the techniques of the present invention. Other embodiments and features of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with the features, refer to the description and to the drawings.
For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts:
It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. In this respect, a coupling between entities may refer to either a direct or an indirect connection. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module, unit and/or element can be formed as processing circuitry that may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
According to a non-limiting embodiment, a cryogenic assembly is provided which includes one or more electrical conductors that provide power and/or other electrical signals to the cryogenic assembly. The electrical conductors include one or more carbon nanotube (CNT) interconnects formed therein that reduce parasitic heat flow into the cryogenic assembly while still providing sufficient conductivity to deliver power and/or signals to the cryogenic assembly. That is, CNT interconnects can be formed on the cryo-side of the connector (e.g., disposed within the vacuum unit) to block the heat flow into the cryogenic assembly while passing the electrical power and signals. The CNT interconnects provide lower overall power requirements necessary for driving the cryogenic assembly. Accordingly, the overall size, weight, and power consumption (SWaP) of the cryogenic assembly can be reduced.
Referring to
The electronic power control module 106 is electrically connected to the vacuum unit 104 via one or more connectors 112. According to an embodiment, the electronic power control module 106 can be configured as a power supply, for example. Each connector 112 can include one or more electrically conductive elements 114 such as, for example, copper wires 114. A first end of the conductive element 114 is connected to the electronic power control module 106 while a second end is connected to the vacuum unit 104. In this manner, the conductive elements 114, i.e., copper wires 114, deliver electrical power and/or control signals from the electronic power control module 106 to the vacuum unit 104. One or more of the electrically conductive elements 114 are also thermally conductive and can emit heat (T1) when delivering power and/or electrical signals from the power control module 106.
The vacuum unit 104 includes a thermal shielding 108 that defines a cavity 109 configured to receive the platform 105. According to an embodiment, the electronic power control module 106 supplies power to the vacuum unit 104. The vacuum unit 104 in turn operates to thermally insulate the cavity 109 from the surrounding external ambient temperature such that the platform 105 is maintained at a desired cryogenic temperature. A sensor 110 is disposed within the cavity 109 and outputs a temperature signal indicating the internal temperature of the cavity 109. Based on the temperature signal, the cryocooler 102 operates to cool the platform 105 at a desired cryogenic temperature.
The connector 112 includes one or more CNT interconnects 116. The CNT interconnects 116 include, for example, a plurality of carbon nanotubes entangled with one another in a yarn-like arrangement. According to an embodiment, the carbon nanotubes include, for example, a combination of semiconductor and metallic nanotubes formed as a matrix material. At cryogenic temperatures (e.g., approximately 120 K or less), the thermal heat flow of the carbon nanotubes are significantly reduced (e.g., X% when compared to thermal heat flow at ambient room temperatures) while the electrical conductivity of the carbon nanotubes still exists. In this manner, the CNT interconnects 116 can block heat flow into the cryogenic assembly 100 while still passing the electrical power and signals delivered by the power control module 106 as discussed in greater detail below.
The CNT interconnects 116 can be spliced in-between portions of one or more conductive elements 114 using, for example, an electroplating and soldering process. Inserting or splicing the sections of the CNT interconnects 116 in-line with the conductive elements 114 minimizes resistive losses and provides significant thermal insulation such that the heat flow entering the cryo-interface of vacuum unit 104 is inhibited. The output of one or more CNT interconnects 116 can be connected to the platform 105 and/or a device supported by the platform. According to an embodiment, the CNT interconnects 116 may have a length of, for example, approximately 0.002 inches (1.0 millimeters), or less. This length, however, is not limited thereto and can be increased. For those applications where short lengths of the CNT interconnect 116 are not tolerable, the diameter of the CNT interconnect 116 can be increased to lower the impact of reduced electrical conductivity. According to an embodiment, the direct current (DC) electrical conductivity of CNT interconnect 116 is approximately 200 times lower than copper at room temperature. However, the CNT interconnect 116 can still conduct electrical power and other signals with minimized loss when very short sections are spliced between conductive segments 117 and the remaining portion of a respective conductive element 114, e.g., copper wire, that is connected directly to the electronic power control module 106.
The thermal conductivity of the CNT interconnects 116 dramatically decreases since heat energy is moved through the matrix material mainly by phonon (rather than electronic) interaction which is greatly reduced. Accordingly, the thermal conductivity of the CNT interconnects 116 is less than the thermal conductivity of the conductive elements 114. These combined properties allow the CNT wire interconnects 116 to conduct electrical signals, while inhibiting heat flow therethrough. As a result, the temperature (T2) of conductive segments 117 spliced to the CNT wire interconnects 116 is less than the temperature (T1) of the conductive elements 114 that are connected directly to the power control module 106. Since the conductive elements 114 (e.g., copper wires) typically contribute to the highest heat flow into conventional cryogenic assemblies, at least one embodiment of the present disclosure includes CNT interconnects 116 that result in lower cryocooler power requirements, while still achieving desired cryogenic temperatures.
The substantial and unexpected thermal conductivity reduction at cryogenic temperature achieved using one or more CNT interconnects 116 act as a thermal insulator that resists heat flow (i.e., heat flow) along the wire allows for a cryogenic assembly 100 having a reduction in overall size, weight, and power (SWaP). In this manner, the cryocooler power efficiency (i.e., the amount of power required to maintain a desired cryogenic temperature of the cavity 109 and/or the platform 105) is improved. Furthermore, a compact cryocooler with increased power efficiency coupled with reduced thermal parasitic behavior can lead to implementation of superconducting electronics across multiple platforms (e.g., ground, ships, airborne, and space).
Referring to
Referring to
Referring to
The heat flow discussed above can be calculated using the following equation (1):
Q=K*A*ΔT/L (1),
where
Q=heat flow;
K=thermal conductivity constant of the conducting material;
A=cross-sectional area of the conducting material;
ΔT=Temperature differential of the conducting material; and
L=length of the conductor
Turning to
Referring to
Turning now to
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
While the various embodiments to the invention have been described, it will be understood that those skilled in the art, both now and in the future, may make various modifications and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.
This application is a non-provisional of U.S. Patent Application Ser. No. 62/035,689, filed Aug. 11, 2014, the disclosure of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62035689 | Aug 2014 | US |
