Optimizing FRC formation and splitting behavior under DC bias field

The field-reversed configuration (FRC), a compact toroidal plasmoid, has a range of potential applications, particularly in nuclear fusion, space propulsion, and plasma research. Various formation methods have been developed to create the magnetic topology required for stable plasma confinement. Here, we propose and investigate a novel formation method using a plasma gun as the plasma source and a DC background magnetic field as the bias field. This approach reduces the device's dependence on high-voltage pulse power supplies for FRC formation and enhances magnetic flux retention. In our experiments, we observed the splitting of elongated FRCs. Specifically, FRCs with an elongation greater than 1.7 and low trapped magnetic flux—a central-to-external magnetic field ratio below 0.6—tended to split during translation. This study demonstrates a new technical scheme for FRC formation, and the experimental results may contribute to the FRC optimization and stability control during translation and compression.