Mechanical Behaviors of Polymer-Based Composite Reinforcements within High-Field Pulsed Magnets.

The development of pulsed magnets capable of generating magnetic fields exceeding 100 Tesla has been recognized as a crucial pursuit for advancing the scientific research on high magnetic fields. However, the operation of magnets at ultra-high magnetic fields often leads to accidental failures at their ends, necessitating a comprehensive exploration of the underlying mechanisms. To this end, this study investigates, for the first time, the mechanical behaviors of Zylon fiber-reinforced polymers (ZFRPs) within pulsed magnets from a composite perspective. The study begins with mechanical testing of ZFRPs, followed by the development of its constitutive model, which incorporates the plasticity and progressive damage. Subsequently, in-depth analyses are performed on a 95-T double-coil prototype that experienced a failure. The outcomes reveal a notable reduction of approximately 45% in both the radial and axial stiffness of ZFRPs, and the primary reason for the failure is traced to the damage incurred by the end ZFRPs of the inner magnet. The projected failure field closely aligns with the experiment. Additionally, two other magnet systems, achieving 90.6 T and 94.88 T, are analyzed. Finally, the discussion delves into the impact of transverse mechanical strength of the reinforcement and axial Lorentz forces on the structural performance of magnets.

Enhancing Oocyte Quality in Aging Mice: Insights from Mesenchymal Stem Cell Therapy and FOXO3a Signaling Pathway Activation.

Ovarian aging reduced the quality of oocytes, resulting in age-related female infertility. It is reported that mesenchymal stem cells (MSCs) therapy can improve age-related ovarian function decline and the success rate of in vitro maturation (IVM) in assisted reproductive therapy. In order to investigate the effectiveness and mechanisms of MSCs to enhance oocyte quality of cumulus oocyte complexes (COCs) in advanced age, this study focus on the respective functional improvement of oocytes and granulosa cells (GCs) from aging mice and further to explore and verify the possible mechanisms. Here, we studied a popular but significant protein of follicular development, Forkhead box O-3a (FOXO3a), which is a transcription factor that mediates a variety of cellular processes, but the functions of which in regulating oocyte quality in MSCs therapy still remain inconclusive. In this study, the RNA-seq data of metaphase II (MII) oocytes and GCs isolated from COCs confirmed that, GCs of immature follicles show the most potential to be the targeted cells of bone marrow mesenchymal stem cells (BMSCs) by FOXO3a signaling pathway. Furthermore, we demonstrated the effectiveness of BMSCs co-culture with aging COCs to enhance oocyte quality and found its mechanism to function via ameliorating the biological function of GCs by alleviating FOXO3a levels. These results provide significant fundamental research on MSCs therapy on ovarian aging, as well as offering guidance for raising the success rate of assisted reproductive technology such IVM in clinical and non-clinical settings.

Fully redundant auxiliary system for gyrotron-based terahertz sources in long-term operation.

The Wuhan National High Magnetic Field Center is incorporating the flat-top pulsed magnetic field (FTPMF) into pulse gyrotrons. It will be the first chance to make a pulse-magnet gyrotron available for generating a long-pulse radiation of 100 ms or above without affecting its high operating frequency and high radiation power. However, unlike continuous wave gyrotrons, pulse gyrotrons in long-term operation have their own challenges, namely, misalignment caused by concussions, much stronger low-frequency electromagnetic interference from the pulse magnet, and inevitable explosion. This article will focus on the difficulties faced by pulse gyrotrons in years of operation, discuss the protection and restoration from failures, and, consequently, propose a fully redundant, explosion-proof, and quickly recoverable auxiliary system for long-term operation of pulse gyrotrons. This system integrates the control unit of traditional pulsed magnets and superconducting magnets so that it can be compatible with any form of gyrotron facilities. Therefore, once the FTPMF or the superconducting magnet is available, the long-pulse radiation will be obtained. Several experimental results, including the most recent explosion, show the reliability of the proposed system.

A broad range frequency measurement method for continuous and pulsed THz waves.

This paper proposes a method to measure the frequency of terahertz (THz) waves based on the Zeeman effect and the high magnetic field technology with a wideband range from 60 GHz to 3 THz. As the frequency of THz waves absorbed by the sample is linear to the magnetic field in the Zeeman effect, the frequency can be measured by the magnetic field strength. A comparison study of THz frequency measurement was carried out in two magnet systems (a superconducting one and a pulsed one) to investigate the performance in two kinds of high magnetic fields. The experimental results of 60-700 GHz show that this method has high resolution (about 0.001%), excellent linearity, and good repeatability. Moreover, the proposed method can measure polychromatic signals simultaneously as well as the single pulse frequency in the order of tens of microseconds.

Predicting the failure of pulsed magnets.

Due to extreme operating conditions, the failure of a magnet frequently occurs in pulsed magnetic field facilities, which not only will disable magnets but also may trigger a violent explosion. Insulation failure occurs more frequently and usually before mechanical failure. Detecting the insulation failure of pulsed magnets is an important issue for pulsed high magnetic field systems. The Partial Discharge (PD) signal is usually used as an insulation monitoring tool. However, the weak PD signals are hidden in the strong dB/dt background signals, which are difficult to be separated. This paper will present a differential PD pick-up coil scheme, and the characteristics and mechanism of the PD signals are discussed based on the experimental results.

Design and test of a flat-top magnetic field system driven by capacitor banks.

An innovative method for generating a flat-top pulsed magnetic field by means of capacitor banks is developed at the Wuhan National High Magnetic Field Center (WHMFC). The system consists of two capacitor banks as they are normally used to generate a pulsed field. The two discharge circuits (the magnet circuit and the auxiliary circuit) are coupled by a pulse transformer such that the electromotive force (EMF) induced via the transformer in the magnet circuit containing the magnet coil is opposed to the EMF of the capacitor bank. At a certain point before the current pulse in the coil reaches its peak, the auxiliary circuit is triggered. With optimized parameters for charging voltage and trigger delay, the current in the magnet circuit can be approximately kept constant to obtain a flat-top. A prototype was developed at the WHMFC; the magnet circuit was energized by seven 1 MJ (3.2 mF/25 kV) capacitor modules and the auxiliary circuit by four 1 MJ modules. Fields up to 41 T with 6 ms flat-top have been obtained with a conventional user magnet used at the WHMFC.