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thermal conductivity of the winding and the constituent
materials and numerically simulated the thermal properties
of the coil to clarify the mechanism of thermal runaway
quantitatively. On the basis of the obtained result, we
discussed how to design the conduction-cooled
superconducting magnets.
POSTER SESSION 13:30 – 15:30
AC LOSSES (II)
THA05PO01
Theoretical estimation of electromagnetic loss at the
movement of superconducting coil in the W7-X
stellarator
F. Gömöry, S. Takacs, Institute of Electrical Engineering
SAS Bratislava; A. Werner, M. Sochor, MPI für
Plasmaphysik Greifswald.
Generation of heat due to the dissipation, occurring when a
superconducting coil experiences a transient in the
magnetic field generated by other coils, was investigated.
Such mechanism could be relevant during energizing the
main magnetic field in the W7-X machine, when the mutual
forces between superconducting coils could lead to their
deformations or movements. In these cases, the heat will
be generated by different kinds of screening currents,
induced in the complex structure of the cable. Significant
paths for current loops have been identified, and the
formulas allowing the estimation of dissipated heat derived.
From the hierarchy of current loops in space and time, it
was possible to break the process in several stages that
could be treated individually. Thus, all the contributions to
the heat generation (eddy current, coupling and hysteresis
losses) could be included into the calculations. Finite
element simulations have been used to determine the
typical transient of magnetic field that could be expected
inside the W7-X coil due to mechanical movement. It was
found that one can foresee magnetic field changes of about
20 mT occurring during 40 milliseconds. Applying the
formulas derived for transient loss for the case of such field
change, the maximum dissipation connected with one such
event was estimated to be less than 0.16 mJ/cm3, which is
tolerable for the magnet design of W7-X.
THA05PO02
Electromagnetic field analysis of an YBCO coated
conductor in multi-layer superconducting cables
S. Sato, N. Amemiya, Yokohama National University.
AC loss reduction is one of the key issues for the
applications of YBCO coated conductor to electrical power
devices. Understanding AC loss characteristics of YBCO
coated conductor is required for AC loss reduction, and
numerical electromagnetic field analysis by finite element
method (FEM) is a very useful tool for this purpose,
because the electromagnetic phenomena inside
superconductors resulting in AC loss generation can be
visualized. In superconducting power cables, YBCO coated
conductors are often assembled in multi-layers in order to
increase their current carrying capacity. In this work,
electromagnetic field analysis of YBCO coated conductors
in multi-layer superconducting power cables with practical
configuration was carried out. The electromagnetic fields in
the YBCO coated conductors of superconducting cable
carrying an AC transport current were calculated using a
numerical model that employed FEM. The AC losses of
multi-layer superconducting power cables were estimated
from the temporal evolutions of the electromagnetic fields.
The number of conductors in each layer and the gap
between the conductors were varied to study their
influence on the AC loss of the cables. The numerically
calculated AC losses were compared with the analytical
values. This work was supported by the New Energy and
Industrial Technology Development Organization (NEDO)
as Collaborative Research and Development of
Fundamental Technologies for Superconductivity
Applications.
THA05PO03
Measurement of the Cryogenic Loss in
Superconducting Magnet System by using
Calorimetric Method
H. Kang, S.W. Park, M.C. Ahn, S.E. Yang, T.K. Ko, Yonsei
University; S.Y. Choi, Sungkyunkwan University; C.J. Lee,
B-Y. Seok, Electro-Mechanical Research Institute, Hyundai
Heavy Industries, Co., Ltd; T.J. Kim, Seongnam
polytechnic college; Y.S. Yoon, Ansan College of
Technology.
There are some ways to measure the AC loss of
superconducting material such as magnetization, transport
current and calorimetric method. Especially, the
calorimetric method is very useful for measuring the AC
Loss of large scale superconducting magnet. The
cryogenic loss of superconducting magnet system
measured by mass flow meter (MFM) includes not only AC
loss of superconducting magnet but also background loss
such as conduction loss through current leads and
electrical wires and radiation loss through cryostat. The
cryogenic loss contains AC loss and background loss is
very important in effective operation of cryogenic
superconducting magnet system. To design and
manufacture the applied superconducting magnet system
such as superconducting transformer and fault current
limiter, this total cryogenic loss should be taken into
consideration carefully. In this investigation, we fabricated
the double pancake, solenoid and bifilar type
superconducting magnet and measure the AC loss of
them. The cryogenic loss was experimentally measured
and separated into background loss and AC loss. The
experimentally measured background loss and AC loss
were compared with the calculated losses by using simple
heat equation and finite element method (FEM),
respectively. These calorimetric measurement method and
calculation method could be very useful to design the
applied superconducting magnet system with pertinent loss
to operate the superconducting magnet system reliably for
a long time.
THA05PO04
Characteristics of Magnetization Loss and Shield
Effect in Multi-stacked Tapes According to Stacking
Geometry
J-K. Lee, Woosuk University; M. Park, H. Lim, H. Lee, G.
Cha, Soonchunhyang University; S. Lee, Korea Electrical
Engineering and Science Research Institute.
AC loss is one of major topics in large AC power high
temperature superconductor(HTS) applications such as
power tranformer, transmission cable and fault current
limiter because it is closely related with operation
efficiency. Multi-stacked tapes conductor should be used to
transport the large current in those power applications. A
research of various arrangements of HTS tapes for multistacked
tapes has been performed to increase a capacity
of transport current in HTS power applications. In this
paper, we studied magnetization loss and shield effect by a
different several arrangements of HTS(BSCCO) tapes such
as Face-to-Face type, regular matrix type(m×2) and
irregular matrix type. As a result, we get the result that the
MT-19 2005, Genova 132