| dc.description.abstract | The Taiwan Axion Search Experiment with Haloscope (TASEH) uses a microwave cavity in a 9 Tesla magnetic field to detect dark matter axions by converting them into photons. A Josephson Parametric Amplifier (JPA) with a high signal-to-noise ratio is used to detect the small signal. Since JPA is sensitive to magnetic fields, a five-layer magnetic shielding is designed: superconducting coils, the first mu-metal shield, lead (Pb) shield, the second mu-metal shield, and niobium (Nb) sheet. These layers use Meissner effect and high permeability to protect the JPA from the magnetic field. We prepare two kinds of joints for superconducting coils using different fabrication processes: the cold-welding method and the lead-bismuth alloy as solder (the PbBi method). By controlling the temperature of the joints higher and under their critical temperature and ramping the magnet, we can examine the joints′ resistance, capability of persistent current, and shielding effect. According to our findings, the resistance upper bound of the PbBi sample is ( R ll frac{L}{ au} sim imes 10^{-13} Omega ), while the cold-welding sample is $R =frac{L}{ au} = frac{90 nH}{21 hours} = 10^{-11} Omega$. The PbBi sample exhibits a greater capability for induced persistent current than the cold-welding sample. Both samples can shield approximately one-third of the external field. We use the PbBi method to make three superconducting coils and install them at positions z= 27cm, 31 cm, and 36 cm (z=0 is at the magnet′s center). The top and the bottom coils can not work correctly in the experiment. The middle coil can shield about $40\%$ of the external field. In the future, we will repair two bad-quality coils and test them under a higher field (greater than 4.2 Tesla). If the coils can work properly in the higher field, we will combine them with the other four shielding layers and then install the JPA device inside the shielding to test the operation of JPA. | en_US |