419 research outputs found
Transport and magnetic Jc of MgB2 strands and small helical coils
The critical current densities of MgB2 monofilamentary strands with and
without SiC additions were measured at 4.2 K. Additionally, magnetic Jc at B =
1 T was measured from 4.2 K to 40 K. Various heat treatment times and
temperatures were investigated for both short samples and small helical coils.
SiC additions were seen to improve high field transport Jc at 4.2 K, but
improvements were not evident at 1 T at any temperature. Transport results were
relatively insensitive to heat treatment times and temperatures for both short
samples and coils in the 700C to 900C range.Comment: 8 text pages, 1 table, 4 fig
Large Upper Critical Field and Irreversibility Field in MgB2 wires with SiC additions
Resistive transition measurements are reported for Magnesium diboride strands
with SiC dopants. The SiC was added as 10 mol of SiC to 90 mol of binary
magnesium diboride. Three different SiC powders were used, the average particle
sizes were 200 nm, 30 nm, and 15 nm. The strands were heat treated for times
ranging from 5 to 30 minutes at temperatures from 675 to 900. Strands with 200
nm size SiC additions had Hirr and Bc2 which maximized at 25.4 T and 29.7 T
after heating at 800C for 30 minutes. The highest values were seen for a strand
with 15 nm SiC heated at 725C for 30 minutes which had a Hirr of 29 T and a Bc2
higher than 33
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