Overview
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When superconductors are in the superconducting state, in which temperature,
magnetic field and current become lower than a critical value, its electrical
resistance becomes zero. Although superconducting wire rod requires a cooling
system to maintain a low-temperature state, having features such as high
current density and extremely low loss, it has a lot of advantages in terms
of energy and environment. The electrical resistance in the superconductor
becomes zero, when DC is applied, but when AC is applied, loss is caused
in a superconductor. In JMAG, the AC loss in a superconductor can be obtained.
This note presents the use of magnetic field analysis to obtain the AC
loss in a superconductive filament. |
AC Loss
Table 1 shows the average AC loss per meter in the longitudinal direction
when applied current is between 50 and 80 % of critical current. Figure
1 and Figure 2 show the AC loss over time.
The AC loss caused by magnetic hysteresis inside the superconductor varies
with the amplitude of the applied current. |
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Current Density Distribution
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Figure 3 and Figure 4 show the current density distribution of a normal
conductor and a superconductor, respectively , when 80% of critical current
is applied. The +Z direction is a positive direction of applied current
amplitude. |
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The applied current amplitude is maximized at 0.025 seconds. At this time,
the current flows uniformly in the normal conductor. Meanwhile, the current
flows toward both sides in the superconductor. This non-uniform current
distribution is the cause of the greater loss. |
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