Degree Type

Dissertation

Date of Award

1992

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

First Advisor

Douglas K. Finnemore

Abstract

Radiation damage studies have been carried out to determine the changes in superconducting critical current density that result for different choices of radiation direction and magnetic field direction relative to the crystallographic axes. Single crystals of YBa[subscript]2Cu[subscript]3O[subscript]7-[delta] were irradiated with a beam of 200 MeV protons directed either parallel to the a-b plane or parallel to the c-axis. These beams created rather light damage in the form of interstitials and voids that subsequently coalesced to clusters of extra atoms in the a-b plane directed along the (100) direction. For low fluence, the main change was in the c-axis critical current density, J[subscript] c[superscript] c. For fluence in the 10[superscript]12-10[superscript]14 protons/cm[superscript]2 range, J[subscript] c[superscript] c showed a major increase whereas the in-plane critical current density, J[subscript] c[superscript] ab increased much less. There also was a large in-plane anisotropy of J[subscript] c[superscript] c with J[subscript] c[superscript] c five to ten times larger for the field parallel to the damage tracks. For fluences in the range of 10[superscript]16 protons/cm[superscript]2, both J[subscript] c[superscript] c and J[subscript] c[superscript] ab showed large increases to values in the 2 x 10[superscript]6 A/cm[superscript]2 range. Annealing studies at room temperature showed that both J[subscript] c[superscript] c and J[subscript] c[superscript] ab decreased 20 to 30%.

DOI

https://doi.org/10.31274/rtd-180813-11220

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Qiang Qian

Language

en

Proquest ID

AAI9311528

File Format

application/pdf

File Size

105 pages

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