Click here to download the abstract booklet in pdf format - MT19 - Infn

current of each double-pancake has been measured at
77K , in order to choose the best pancakes for assembling
in higher magnetic field region. The magnet has been
tested at 4.2K with a current of 163 A in a liquid helium
bath, in a background field of 3 T for a total field of 7 T. In
collaboration with CISE, magnet tests are in progress by
using 65K sub-cooled liquid nitrogen and 27K liquid neon
baths.
TUA01PO03
Test of a Variable-Field-Direction Superconducting
Magnet
S. Matsumoto, T. Kiyoshi, NIMS
Withdrawn.
TUA01PO04
A Solid-Nitrogen Cooled High-Temperature
Superconducting Magnet for use in
Magnetohydrodynamic Marine Propulsion
P.W. Hales, H. Jones, Oxford University; S. Milward, S.
Harrison, Space Cryomagnetics Ltd.
A small high-temperature superconducting (HTS) magnet
has been produced as part of a magnetohydrodynamic
(MHD) propulsion unit to power a model boat. The magnet
is wound from 6 pancake coils of Bi-Sr-Ca-Cu-O HTS tape
(BSCCO-2223), and is conduction cooled using an
onboard “thermal battery”, containing 3 litres of solid
nitrogen. The magnet is racetrack shaped, and aluminium
electrodes are placed along the straights of the magnet to
pass an electric current through the saltwater,
perpendicular to the magnetic field. Power for the magnet
and the electrodes is provided by onboard sealed lead acid
batteries, resulting in a fully ‘stand-alone’ magnet system,
capable of up to 1.25 hours of continuous operation on one
battery pack. This system was integrated into a model boat
hull (approx. 1.2m long x 0.6m wide), which was
successfully launched on 29th March 2004 at the Culham
Science Centre in Abingdon, England. A top speed of
~3cm/sec was reached during the first trial.
TUA01PO05
Properties of a YBCO pancake coil operating with AC
current at frequencies up to 1000 Hz
M. Polak, E. Demencik, L. Jansak, Institute of Electrical
Engineering - Bratislava; P. Barnes, Air Force Research
Laboratory, Wright-Patterson AFB; G. Levin, National
Research Council, Wright-Patterson AFB; C. Thieme,
American Superconductors Corporation.
A small pancake coil wound using ~1.2m of YBCO coated
conductor 10 mm wide and impregnated by epoxy resin
was measured and tested. In the DC regime, we measured
the I-V curve of the coil, the hysteresis of the magnetic
field-current curve at liquid nitrogen temperature and the
radial component of the coil field at the coil edges. AC
losses in the frequency range from 100 Hz up to 1000 Hz
at 77 K and at temperatures down to 66 K were also
measured. The frequency dependence of losses and
critical currents of a short sample at 77 K were also
measured and compared with those for the coil.
TUA01PO06
Coils made from Monfilamentary and multifilamentary
MgB2 strand
M.D. Sumption, M. Bhatia, F. Buta, S. Bohnenstiehl, E.
Collings, LASM, MSE, Ohio State University; M. Tomsic, J.
Phillips, Hyper Tech Research.
Three solenoidal coils have been wound and with MgB2
strand and tested for transport properties. Each coil was
wound with a different strand. The first was a
monofilamentary strand with a pure Cu sheath, while the
second and the third were seven filament strand with Nbreaction
barriers, Cu stabilization, and an outer monel
sheath. The wires were first S-glass insulated, then wound
onto an OFHC Cu former. The coils were then heat treated
(HT) at 675/30, 700C/20 min, and 700/20, for the first,
second, and third coils, respectively. Smaller (1 m)
segments of representative strand were also wound into
barrel-form samples and HT along with the coils. After HT
the coils were epoxy impregnated. Transport Jc
measurements were performed between various pairs of
taps along the coil lengths. Measurements were made
initially in liquid helium, and then by conduction cooling as
a function of temperature up to 30 K. Homogeneity of
response along the coils was investigated and a
comparison to the short sample results was made. The coil
contained more than 100 m of 1.0 mm OD strand for first
coil and 0.8mm OD strand for the second and the third coil.
The 7 strand coil reached 222 A at 4.2 K, self field, with a
Jc of 300 kA/cm2 in the SC and a winding pack Je of 23
kA/cm2. At 20 K the critical current density values were
175 kA/cm2 and 13.4 kA/cm2. Magnet bore fields of 1.5 T
and 0.87 T were achieved at 4.2 K and 20 K, respectively.
TUA01PO07
A 0.6T/600 mm RT Solid Nitrogen Cooled MgB2
Demosntration Coil for MRI - A Status Report
J. Bascuñán, H. Lee, E. Bobrov, S-Y. Hahn, Y. Iwasa, MIT-
Francis Bitter Magnet Laboratory; M. Tomsic, M.
Rindfleisch, Hyper Tech Research Inc.
Aiming to demonstrate feasibility and practicality of a low
cost superconducting MRI magnet system targeted for use
in small hospitals, rural communities and underdeveloped
countries, the MIT-Francis Bitter Magnet Laboratory has
developed a 0.6T/600 mm room temperature
demonstration coil wound with multifilament MgB2
conductor and cooled via an innovative cryogenic
design/operation. The coil is to be maintained cold by solid
nitrogen which in turn is solidified by a cryocooler. In the
event of a power failure the cryocooler is automatically
thermally decoupled from the system. In this paper we
present details of the MgB2 conductor, winding process,
and preliminary test results of the current-carrying
performance of the conductively cooled coils in zero
background field and over the 10 – 30 K temperature
range.
TUA01PO08
Relaxation of trapped magnetic field in 100m-long
class MgB2 solenoid coil in persistent current mode
operation
M. Takahashi, K. Tanaka, M. Okada, HRL, Hitachi, Ltd.
We succeeded in the persistent current mode operation of
100m-long class MgB2 solenoid coil with persistent current
switch (PCS). The coil was fabricated using metalsheathed
MgB2 mono-core wires and using Wind & React
process (heat treatment at 938K for 3600s). MgB2 wires
were produced applying the in-situ PIT method consisting
Mg and amorphous B powders. The PCS was fabricated
with Cu-30wt%Ni sheathed NbTi multifilamentary wires.
We confirmed the ability to trap 0.67T magnetic field with
persistent current of 53.8A. From the relaxation of
persistent current up to 28800s, relaxation times were
estimated to be t > 15000s,showing resistance in overall
current loop below 10-9 V/A. The average rate of magnetic
relaxation was 7.5×10-5/h with inductance L of 8mH.
57 MT-19 2005, Genova