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morphology and superconducting properties (Jc, Hc2) on
the sintering parameters and the dopant material and
concentration was studied by X-Ray, EDAX, SEM methods
and magnetization measurements.
MOA01PO11
High Hc2 and Hirr in MgB2 coated-conductor fibers
X.X. Xi, A.V. Pogrebnyakov, J. Chen, Q. Li, J.M. Redwing,
Pennsylvania State University; V. Ferrando, University of
Genoa/INFM-LAMIA; P. Orgiani, University of
Naples/INFM-Coherentia; J. E. Giencke, C. B. Eom,
Department of Materials Science and Engineering and
Applied Superconductivity Center, University of Wisconsin.
MgB2 coated-conductor fibers were deposited on SiC
fibers by hybrid physical-chemical vapor deposition
(HPCVD). X-ray diffraction shows polycrystalline MgB2
with Mg2Si peaks. The clean MgB2 fibers have high Tc of
~ 40 K. When alloyed with carbon, the upper critical field
Hc2 and irreversibility field Hirr of the fibers increase
dramatically. The highest measured value of Hc2 is ~ 55 T
and of Hirr is ~ 40 T at low temperatures. The results show
that, first, epitaxy is not necessary in achieving the
extraordinarily high values (over 60 T) previously reported
in textured carbon-alloyed thin MgB2 films; and second,
coated conductor using HPCVD is a viable approach for
high performance MgB2 conductors for high-field magnets.
POSTER SESSION 13:30 – 15:30
STRUCTURAL AND MAGNETIC MATERIALS &
INSULATION
MOA02PO01
Mechanical Properties of Zylon/Epoxy Composite at
295 K and 77 K
R.P. Walsh, C. Swenson, NHMFL-FSU; N. Bednar, Perseo
Engineering.
Zylon fiber, poly(p-phenylene-2,6-benzobisoxazole) PBO
has found recent use in high-field pulse magnet coil
development because of this fiber’s extremely high 295K
ultimate tensile strength (>5.0 GPa) and elastic modulus
(280 GPa). Although the fiber properties are well
documented, there is limited data available with respect to
its properties in fiber/epoxy composite form and at low
temperatures. A test program has been conducted to
investigate the properties one can attain from a
Zylon/epoxy composite, produced using pulse magnet
fabrication techniques (race track specimens are fabricated
using various winding tensions and outside form
techniques). The relationship between winding tension,
ultimate tensile strength (UTS), and filling factor of the
fibers is studied. The ultimate tensile strength (UTS),
elastic modulus, and maximum strain at failure of a
unidirectional Zylon/epoxy matrix composite are measured
at both 295K and 77K. The thermal contraction of the
composites are also measured and reported.
MOA02PO02
RF Magnetic Shielding Effects of the Compound
Material Constructed from the Ferrite and Bincho-
Charcoal Plates
H. Norikane, S. Gokyu, A. Omura, M. Itoh, Interdisc. Grad.
School of Science and Engineering, Kinki University; Y.
Hotta, EMC Engineering Laboratory Ltd.
RF magnetic shielding materials are used to reduce the
influence of environmental electromagnetic waves, and to
protect the environment from the leakage of any generated
electromagnetic waves. In present study, RF magnetic
shielding degree SDh of a compound material, such as a
bincho-charcoal plate superimposed by ferrite plate, is
measured by use of the measuring cell for the near field
(46 mm wide, 46 mm in height, 55 mm deep, 2 mm thick).
The value of SDh for a ferrite plate was found to increase
as the frequency increased over range from 1 MHz (SDh at
1 MHz: 20 dB) to 20 MHz (SDh at 20 MHz: 35 dB), and to
decrease in frequency region from 20 MHz to 1 GHz (SDh
at 1 GHz: 9 dB). However, it was found that the value of
SDh for the bincho-charcoal plate is held at 0 dB in
frequency range of 1 MHz - 8 MHz, and then increases
over the frequency range of 8 MHz - 1 GHz (SDh at 1 GHz:
35 dB). Here, bincho-charcoal is obtained from very hard
oak, sintered under high temperature conditions. The RF
magnetic shielding characteristics were found to be
improved by using the compound material, in the frequency
region from 7 MHz to 1 GHz, that is, the value of SDh is
held at approximately 35 dB on these wide frequency
region. The present paper examines the effects of RF
electromagnetic shielding on the compound materials. This
includes the RF magnetic and electric shielding degrees,
SDh and SDe, as a function of frequency, and the SDh and
SDe as a function of RF power.
MOA02PO03
An innovating insulation for Nb3Sn Wind & React
coils: electrical tests
L. Quettier, J.M. Rey, F. Rondeaux, CEA Saclay; A.
Puigsegur, E. Prouzet, Institut Européen des Membranes -
CNRS Montpellier.
If Nb3Sn is the best superconductor candidate for the
realisation of high field magnets (>10-11 Teslas), its
implementation remains delicate because of the great
brittleness of material after the heat treatment necessary to
the formation of Nb3Sn compounds. The conventional
insulation for Nb3Sn Wind & React coils requires to
perform, after the heat treatment, a vacuum resin
impregnation, which adds to the cost and raises failure risk.
We have proposed a one-step innovating ceramic
insulation deposited directly on the un-reacted conducting
cable. After the heat treatment necessary to the formation
of the Nb3Sn, we obtain a coil having a mechanical
cohesion, while maintaining a proper conductor positioning
and a suitable electric insulation. We have shown that
using this insulation in a coil manufacture process doesn’t
affect the electrical properties of the Nb3Sn wires. A
solenoid of small dimensions (9 * 20 turns on an internal
diameter of 22 mm) has produced a magnetic field of 3.8 T
under 740 A. It was tested with success in high external
magnetic fields: the quench limits have been imposed by
the strand and the insulation was not damaged.
MOA02PO04
The Structure and Magnetic Properties of
Hydroextruded Dysprosium
A. Bulatov, M. Lazareva, M. Tikhonovsky, N. Chernyak,
National Science Center "Kharkov Institute of Physics &
Technology" (NSC KIPT).
The low-temperature collinear ferromagnetic Dy that has
high saturation flux density is a promising material for
building magnetic flux concentrators for various cryogenic
magnetic systems. An impediment for its employment in
the polycrystalline isotropic state is the giant
magnetocrystalline anisotropy. The problem has been
resolved of crystalline structure control throughout the
mass volume. The review of the experimental results
indicated that: 1.As a result of the plastic strain obtained
via the technique of Dy room temperature hydroextrusion,
the favorable crystallographic grain orientation
MT-19 2005, Genova 26