• FAQ
    • Deposit your work
    • Login
    View Item 
    •   Rice Scholarship Home
    • Rice University Graduate Electronic Theses and Dissertations
    • Rice University Electronic Theses and Dissertations
    • View Item
    •   Rice Scholarship Home
    • Rice University Graduate Electronic Theses and Dissertations
    • Rice University Electronic Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Measurements of the trapped flux in a long hollow superconducting cylinder

    Thumbnail
    Name:
    RICE0902.pdf
    Size:
    2.709Mb
    Format:
    PDF
    View/Open
    Author
    Smith, Todd Iversen
    Date
    1963
    Advisor
    Rorschach, Harold E., Jr.
    Degree
    Master of Arts
    Abstract
    The recent discovery of quantized flux appeared to explain the extremelylong lifetime .of persistent currents in superconductors. The existence of the flux quantum indicated that the energy of a superconductor in a current carrying state is a local minimum with respect to current variations if the flux is an integer number of flux quanta. The stability is thus explained as a greatly reduced transition probability for the large current changes needed to lower the energy. Bloch and Rorschach have investigated the energetic stability of persistent currents in a long hollow superconducting cylinder, using the charged Bose gas model proposed by Schafroth. The criterion for stability was that the energy of the system could not be lowered by single particle transitions. They showed that the maximum stable magnetic field which could be trapped inside the cylinder was a function of the externally applied field and the sample dimensions, and could be less than the critical field Hc. In contrast to these results one would predict from Maxwell's equations, together with the infinite conductivity of a superconductor, that it should be possible to trap and maintain any field inside the cylinder as long as both the internal and external fields are smaller than the critical field. Measurements have been made of the maximum stable field inside a hollow tin cylinder (wall thickness d 1.5 mm, inner radius r = 7.5 mm, length L =12.5 mm) as a function of the externally applied field. The results seem to be in qualitative agreement with the Bose gas theory, in that the maximum internal field is a function of the external field. However, the theory predicts that when the external field is zero the maximum internal field should be d/r Hc = 0.2 Hc, while the experimentally determined value is 0.6 Hc. It is possible that these results are due to end effects, as the field at the cylinder walls is greater at the ends than at the center. The rate of decay of the internal field when the external field is changed indicates that these end effects may be important.
    Citation
    Smith, Todd Iversen. "Measurements of the trapped flux in a long hollow superconducting cylinder." (1963) Master’s Thesis, Rice University. http://hdl.handle.net/1911/89868.
    Metadata
    Show full item record
    Collections
    • Rice University Electronic Theses and Dissertations [10740]

    Home | FAQ | Contact Us
    Managed by the Digital Scholarship Services at Fondren Library, Rice University
    Physical Address: 6100 Main Street, Houston, Texas 77005
    Mailing Address: MS-44, P.O.BOX 1892, Houston, Texas 77251-1892
     

     

    Browse

    Entire ArchiveCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsTypeThis CollectionBy Issue DateAuthorsTitlesSubjectsType

    My Account

    Login

    Statistics

    View Usage Statistics

    Home | FAQ | Contact Us
    Managed by the Digital Scholarship Services at Fondren Library, Rice University
    Physical Address: 6100 Main Street, Houston, Texas 77005
    Mailing Address: MS-44, P.O.BOX 1892, Houston, Texas 77251-1892