N121-049 TITLE: Reliable, High Temperature Superconducting (HTS) Tape Connections

TECHNOLOGY AREAS: Materials/Processes

ACQUISITION PROGRAM: PMS 501, LCS Program, ACAT 1

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: The objective is the development of an innovative approach and any associated manufacturing process to enable reliable field connections for superconducting tape joints for use in naval applications.

DESCRIPTION: The Navy is developing several superconducting systems for use in future ships and submarines to reduce system weight, energy usage, and installed volume. These systems such as degaussing and power distribution systems rely on superconducting cables housed in a flexible cryostat to pass current and power from one source to another. Current cable designs consist of multiple High Temperature Superconductor (HTS) tapes bundled together within semi-flexible cryostat housing. It can be difficult to terminate these tapes within the confined spaces inside the flexible cryostat (less than 1 inch). A reliable HTS tape connection technology is desired for repair and installation of HTS cables. The ability to repair cables in the field in lieu of replacing the entire length of cable (as is currently done) necessitates the development of a reliable, alternative method of creating HTS tape connections. An alternative approach to connecting superconducting tapes together to form tape joints could greatly enhance the attractiveness of HTS systems by increasing the ease of installation and repair as well as reducing the cost of materials.

The Navy seeks technology and the associated manufacturing processes to provide for improved field connections of HTS tape joints. Of particular emphasis are concepts providing low electrical losses (< 2 micro Ohms), high connection reliability (no failures), and a quick and simplified method of connecting these joints where the cryostat cable link together (under 1 hour for all tape connections). The use of soldering is not preferred due to the time and space required to connect multiple HTS tape joints in a confined space (less than 1 inch). Given the application, the proposed concepts should be rugged in order to survive in a shipboard environment. A technical challenge will be achieving the proper joint pressure to minimize electrical contact resistance while maintaining the integrity of the HTS tape. It is anticipated that 10-20 tapes will need to be used per cable assembly and would need to be able to withstand up to 500VDC. The method for connections would need to be completed by a nonskilled laborer in the field with little to no special tooling required.

PHASE I: Demonstrate the feasibility of a novel, improved approach for the field connection of superconducting tapes able to operate with Navy cryogenic systems as defined above. Perform bench top experimentation, where applicable, as a means of demonstrating the identified concepts. Establish validation goals and metrics to analyze the feasibility of the proposed solution. Provide a Phase II development approach and schedule that contains discrete milestones for product development.

PHASE II: Develop, demonstrate and fabricate a prototype as identified in Phase I. In a laboratory environment, demonstrate that the prototype meets the performance goals established in Phase I. Verify final prototype operation in a representative laboratory environment and provide results. Develop a cost benefit analysis and a Phase III installation, testing, and validation plan.

PHASE III: Upon successful Phase II completion, the company will work with the Navy to transition the HTS tape connection technology into an operational degaussing (or other cryogenic application requiring tape connections) system aboard a Navy ship. The company will support the Navy in an effort to install any necessary components required to allow for use of this technology in an extended shipboard testing operational environment. The company will also support the Navy for test and validation to certify and qualify the technology for Navy use.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: A simple field connection of HTS tapes may be of use in land-based superconducting power cables and power delivery applications. When land-based HTS power cables transition from R&D projects to commercial installations, there may be instances of tight spaces where utilizing this type of design would benefit overall installation.

REFERENCES:
1. B. Fitzpatrick, J. Kephart, E. M. Golda, "Characterization of Gaseous Helium Flow Cryogen in a Flexible Cryostat for Naval Applications of High Temperature Superconductors," IEEE Trans. App. Super., Vol. 17, No. 2, 2007.

2. American Superconductor, "High Temperature Superconductor Degaussing Coil System," www.amsc.com, 2010.

3. Innovation Park Newsletter, "Tai-Yang research Company Wins SBIR Phase II Contract," innovation-park.com, Page 2, 2008.

KEYWORDS: cryogenics; superconductor; cryostat; degaussing; HTS; High Temperature Superconducting;

** TOPIC AUTHOR (TPOC) **

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