Self-field quench behavior of multifilamentary MgB₂ wires in liquid helium

Self-field quench behavior of two types of multifilamentary MgB₂ wires with different numbers of filaments and outer sheath materials are tested. One sample type has a Glidcop outer sheath and the other has a Monel outer sheath. Samples are bath cooled in liquid helium at 4.2 K. A normal zone is initiated by a heater wound around the sample. Voltage and temperature along the samples are monitored and results from two sample types are compared. For the same transport current and end-to-end voltage, the normal zone length is shorter in the Monel-sheathed sample than that in the Glidcop-sheathed sample, which leads to higher electrical field and temperature gradient in the Monel-sheathed sample. The relationship between the voltage and hot-spot temperature is discussed for both samples. Quench energy and normal zone propagation velocity are measured at different transport currents and compared with the existing data for similar samples measured in an adiabatic environment.