Numerical simulation of a hybrid trapped field magnet lens (HTFML) magnetized by pulsed fields

Abstract

<jats:title>Abstract</jats:title> <jats:p>The hybrid trapped field magnet lens (HTFML) is a promising device that is able to concentrate a magnetic field higher than an applied background field continuously, even after removing a background field, which was conceptually proposed by the authors in 2018. We have numerically investigated the HTFML performance, consisting of a REBaCuO cylindrical magnetic lens and REBaCuO trapped field magnet (TFM) cylinder, magnetized by pulsed fields. Single magnetic pulses were applied ranging from <jats:italic>B</jats:italic> <jats:sub>app</jats:sub> = 1.5 T to 5.0 T at the operating temperature of <jats:italic>T</jats:italic> <jats:sub>s</jats:sub> = 30, 40 and 50 K, and the performance was compared with that of the single REBaCuO TFM cylinder. The HTFML effect was clearly confirmed for the lower <jats:italic>B</jats:italic> <jats:sub>app</jats:sub> values. However, for the higher <jats:italic>B</jats:italic> <jats:sub>app</jats:sub> values, the trapped field in the magnetic lens bore was nearly equal to or slightly lower than that for the single TFM cylinder because of a weakened lens effect due to magnetic flux penetration into the lens. A temperature rise in the REBaCuO magnetic lens and TFM cylinder was also observed. These results strongly suggest that lowering the temperature of the REBaCuO magnetic lens could enhance the HTFML effect even for higher <jats:italic>B</jats:italic> <jats:sub>app</jats:sub>.</jats:p>