A device and method for making a persistent joint allowing end terminations of superconducting MgB
2 wire to be joined with a superconducting bridge. Superconducting electromagnetic coils may be joined in series or joining of coil assemblies to current sources and the two ends of a persistent switch. The device includes wire filaments with end preparation exposing reacted MgB
2 , inserted into a block and surrounded with Mg+B and/or MgB
2 in powder, solid, slurry or sol-gel form and subsequently reacted to establish a bridge of superconducting MgB
2 electrically connecting the superconducting MgB
2 wires. Autonomous operation of the superconducting background magnet coils in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) devices are allowed, or similar devices where autonomous operation of an MgB
2 based superconducting magnet is required. The low resistant joint will also be beneficial for other superconducting applications such as fault current limiters, motors, generators, etc.