Rise-Time Elongation Effects on Trapped Field and Temperature Rise in Pulse Field Magnetization for High Temperature Superconducting Bulk

概要

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Pulse field magnetization (PFM) using a magnetic pulse of $B_{\text{ex}}=3.83--5.53$ T with various rise times $t_{\text{r}}$ ($=6--20$ ms) has been performed for the cryocooled SmBaCuO bulk superconductor starting at the initial temperature of 40 K. The time evolutions of temperature $T(t)$ and local field $B_{\text{L}}^{\text{P}}(t)$ have been measured on the bulk surface after applying the magnetic pulse. With increasing $t_{\text{r}}$, the temperature rise $\Delta T$ and the trapped field $B_{\text{T}}^{\text{P}}$ increase for $B_{\text{ex}}\leq 4.70$ T and decrease for $B_{\text{ex}}=5.53$ T. The rise time $t_{\text{r}}$ required to realize the optimum $B_{\text{T}}^{\text{P}}$ has been found to become longer for a smaller pulse field $B_{\text{ex}}$. From the analyses of the generated heat $Q$ after five successive applications of pulses (Nos. 1–5) with the same amplitude, the $Q$(No. 5) value, which can be regarded as the viscous loss $Q_{\text{v}}$, decreases with increasing $t_{\text{r}}$, due mainly to the decrease in the flux propagation velocity $v$ in the bulk with longer $t_{\text{r}}$.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-07-15