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Friday, September 23, 2005
PARALLEL SESSION 8:30 – 10:00
(Scirocco/Libeccio room)
PULSE MAGNETS (II)
FRM1OR1
ARMS: A successful European programme for a 80 T
user magnet
H. Jones, University of Oxford; P. Frings, O. Portugall
LNCMP, Toulouse France; M. von Ortenberg, Humboldt
University at Berlin; A. Lagutin, F. Herlach, Katholieke
Universiteit Leuven; L. Van Bockstal, Metis Instruments
and Equipment nv, Belgium.
ARMS is the acronym for Advanced Research Magnet
Systems - a project under the European Union's 5th
Framework Research Infrastructures programme. Eight
partners co-operated to produce a coil-ex / coil-in pulsed
field magnet, the two components of which were energised
by separate capacitive power supplies. The location of the
finished magnet was LNCMP, Toulouse, whose 14 MJ
capacitor bank powered the coil-ex. A small 100 KJ, fast
bank powered the coil-in. In this paper, the evolution of the
coils and the conductors and other materials is described
as well as the testing and final useage for condensed
matter experiments in fields up to 76 T. The future direction
of high fields in Europe, post - ARMS, will also be
addressed.
FRM1OR2
Accuracy and Uncertainty of the Material Testing Data
for Magnet Design
K. Han, R. Walsh, Y. Xin, NHMFL.
Withdrawn.
FRM1OR3
Magnetic Misalignment Matrix and Current Lead
Configuration Study for the NHMFL 100 Tesla Pulsed
Magnet System
J. Toth, C. Swenson, Y. Viouchkov, NHMFL.
Withdrawn.
FRM1OR4
Development of high strength conductors for pulsed
high field magnets
J. Freudenberger, A. Gaganov, E. Botcharova, L. Schultz,
IFW Dresden.
Withdrawn.
FRM1OR5
Experimental and theoretical analysis of the heat
distribution in pulsed magnets.
F.C. Herlach, K.U. Leuven - Natuurkunde - LVSM; T. Peng,
HUST, Wuhan; J. Vanacken, LNCMP, Toulouse.
Joule heating is a critical issue with pulsed magnets; it
determines the feasible combination of pulse duration and
peak field with respect to the power supply, as well as the
durability of the magnet. It is straightforward to calculate
the average heating from the energy that is dumped into
the magnet during the pulse. There are two effects that
result in shifting the heating from the outer layers towards
the inner radius of the winding: magneto-resistance and the
skin effect. This is because both effects depend on the
magnetic field that is of course stronger at the inner layers.
The temperature difference could easily be of the order of
100 K for fields in the range above 50 T. For magnetoresistance,
the magnetic field dependence is not precisely
known for many of the conductors used in the coils.
Calculation of the skin effect requires in principle the
solution of partial differential equations governing the
current distribution in the wires, but approximations can be
made that permit analytical calculation. We measured the
temperature distribution by means of a series of
thermocouples embedded in the winding and compare the
results with our calculations. These measurements also are
useful for the optimization of the cooling process after the
pulse. This optimization could considerably shorten the
cool-down time between pulses.
FRM1OR6
Spheroidization effects on the electrical and magnetic
properties of a Cu15%Nb composite
M.J.R. Sandim, H. Sandim, R. Renzetti, Department of
Materials Engineering - FAENQUIL; D. Stamopoulos,
Institute of Materials Science, NCSR; M. das Virgens, L.
Ghivelder, IF-UFRJ.
We report on the microstructural evolution in Cu15%Nb
multifilamentary conductors upon annealing and the
corresponding effects on their electrical and magnetic
properties. Vacuum annealing of the composite was
performed from 300 to 1000 "C at times varying from 1 to
120 min. The microstructure of niobium filaments was
investigated using scanning electron microscopy (SEM)
and Vickers microhardness. Electrical resistance versus
temperature curves of as-drawn and annealed specimens
were determined using the four-probe technique between 5
and 12 K. The variation in the resistivity ratio r295 K/r77K
was also determined. The DC magnetic measurements as
a function of magnetic field were performed at 4.2 K and at
magnetic fields up to 2 T. A closer inspection in SEM
reveals important microstructural changes in annealed
niobium ribbons in terms of morphology (spheroidization).
Concerning the annealed samples, in the normal state it
was observed an increase in the electrical resistivity with
increasing annealing temperature. The annealing strongly
affects the shape of the magnetization loops, which display
a double-peak feature. The kinetics of spheroidization
exhibited by niobium ribbons is mirrored in the changes of
the characteristics of magnetization curves with annealing
time. The aim of the present work is understanding the
microstructural changes associated with spheroidization in
Cu15%Nb, as well as its influence on the electrical and
magnetic properties.
PARALLEL SESSION 8:30 – 10:40
(Maestrale room)
LHC MAGNETS
FRM2OR1
Trends in field quality along the production of the LHC
dipoles and differences among manufacturers
E. Todesco, C. Vollinger, P. Hagen, CERN.
More than two thirds of the dipoles of the Large Hadron
Collider have been manufactured and their field content
measured at room temperature. In this paper we make a
review of the trends that have been observed during the
production. In some cases, the trends have been traced
back to the displacements of conductors with respect to the
nominal layout. The analysis allows detecting the most
delicate zones in the superconducting coil as far as field
quality is concerned. The second part of the paper makes
the point of the observed differences in field quality
between the three manufacturers. The analysis allows
149 MT-19 2005, Genova