Apparatus and method for critical current measurements

Patent · 01 January 1992

OSTI ID:868412

Martin, Joe A ^[1]; Dye, Robert C ^[2]

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1. Espanola, NM
2. Los Alamos, NM

An apparatus for the measurement of the critical current of a superconductive sample, e.g., a clad superconductive sample, the apparatus including a conductive coil, a means for maintaining the coil in proximity to a superconductive sample, an electrical connection means for passing a low amplitude alternating current through the coil, a cooling means for maintaining the superconductive sample at a preselected temperature, a means for passing a current through the superconductive sample, and, a means for monitoring reactance of the coil, is disclosed, together with a process of measuring the critical current of a superconductive material, e.g., a clad superconductive material, by placing a superconductive material into the vicinity of the conductive coil of such an apparatus, cooling the superconductive material to a preselected temperature, passing a low amplitude alternating current through the coil, the alternating current capable of generating a magnetic field sufficient to penetrate, e.g., any cladding, and to induce eddy currents in the superconductive material, passing a steadily increasing current through the superconductive material, the current characterized as having a different frequency than the alternating current, and, monitoring the reactance of the coil with a phase sensitive detector as the current passed through the superconductive material is steadily increased whereby critical current of the superconductive material can be observed as the point whereat a component of impedance deviates.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM
• DOE Contract Number: W-7405-ENG-36
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 5134360
• OSTI ID: 868412
• Country of Publication: United States
• Language: English

Related Subjects

/324/505/
alternating
alternating current
amplitude
apparatus
apparatus including
capable
characterized
clad
clad superconductive
cladding
coil
component
conductive
conductive coil
conductive material
connection
connection means
cooling
cooling means
critical
critical current
current
current measurement
current measurements
current pass
current passed
currents
detector
deviates
disclosed
eddy
eddy current
eddy currents
electrical
electrical connection
field
frequency
generating
impedance
including
increased
increasing
induce
induce eddy
magnetic
magnetic field
maintaining
material
means
measurement
measurements
measuring
method
monitoring
observed
passed
passing
penetrate
phase
phase sensitive
placing
preselected
preselected temperature
process
proximity
reactance
sample
selected temperature
sensitive
sensitive detector
steadily
sufficient
superconductive
superconductive material
superconductive sample
temperature
vicinity
whereat
whereby