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Based on the experimental verification of our previous work, this article proposes to use a linear-motor type flux pump with a through-wall excitation structure in the 16.9 kW high temperature superconducting (HTS) synchronous motor. At a working temperature of around 30 K, the HTS flux pump serves as a DC power source to provide contactless current injection to the four non-insulated racetrack coils soldered in series in the superconducting motor. The use of this structure mainly solves the problem of severe heating of the flux pump in the low-temperature vacuum environment of superconducting motors. This article mainly introduces the design and installation of excitation and cooling structures for superconducting motor, and develops a real-time data acquisition system for superconducting motor using Python and QT design interface software. It has functions such as data display, real-time curve drawing, and data storage. Finally, according to the design, the flux pump of through-wall excited superconducting motor is made and the single superconducting tape pumping current reaches 162 A at 77 K. The next step is to carry out the pumping current experiment on the superconducting motor of through-wall excited flux pump.

As a travelling-wave flux pump, the HTS dynamo generates a DC-biased AC travelling wave on the HTS stator tape placed in air-gap, which can output large DC current into an HTS coil without the need for current leads, thus effectively reducing heat leakage and operational cost comparing with conventional contact power supplies. In this paper, we introduce a method to enable symmetric bipolar output of the HTS dynamo, based on the “four-quadrant” control originates from the theory of macroscopic magnetic coupling. This method uses N-S arrangement of permanent magnets embedded on the magnetic disk and in addition to a DC bias coil. In this work, we demonstrate the use of the DC bias coil to freely adjust the DC output current of the HTS dynamo from −40.3 A to +40.5 A, without disturbing its rotating state. We also demonstrated that the DC output current can be symmetrically reversed by reversing the direction of the DC bias field, thus enabling the HTS dynamo with bipolar output. In addition, we developed a feedback control algorithm to control the output current with an accuracy of 0.15 A, by controlling the on and off states of the DC coil. This work enables the HTS dynamo as an accurate bipolar wireless power supply, which opens its routes for various applications of HTS magnets that require accurate current control, especially for high-demanding areas such as magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR).

Two-dimensional (2D) metal halide perovskites, such as BA2SnI4(BA═CH3(CH2)3NH3), exhibit an enhanced charge carrier lifetime in experiments under strain. Experiments suggest that significant compression of the BA molecule, rather than of the inorganic lattice, contributes to this enhancement. To elucidate the underlying physical mechanism, we apply a moderate compressive strain to the entire system and subsequently introduce significant compression to the BA molecules. We then perform ab initio nonadiabatic molecular dynamics simulations of nonradiative electron–hole recombination. We observe that the overall lattice compression reduces atomic motions and decreases nonadiabatic coupling, thereby delaying electron–hole recombination. Additionally, compression of the BA molecules enhances hydrogen bonding between the BA molecules and iodine atoms, which lengthens the Sn–I bonds, distorts the [SnI6]4–octahedra, and suppresses atomic motions further, thus reducing nonadiabatic coupling. Also, the elongated Sn–I bonds and weakened antibonding interactions increase the band gap. Altogether, the compression delays the nonradiative electron–hole recombination by more than a factor of 3. Our simulations provide new and valuable physical insights into how compressive strain, accommodated primarily by the organic ligands, positively influences the optoelectronic properties of 2D layered halide perovskites, offering a promising pathway for further performance improvements.