Detection of poloidal magnetic flux emission from a plasma focus -- First Experiments at Sofia University

The existence of axial (poloidal) magnetic field in a plasma focus and its significance in plasma focus phenomenology has been extensively discussed in a recent review paper. The poloidal magnetic field is a part of the transient 3-dimensional magnetic field structures which arise spontaneously, accelerate ions and keep them moving in trajectories that repeatedly cross a dense and warm plasma target. This is the origin of the abnormally high fusion reaction rate of the plasma focus, which has been known since the 1960s but has begun to be understood quite recently. Further progress now depends on explorations of the global aspects of the evolution of poloidal magnetic field. However, well-known experimental difficulties involved in standard techniques of axial magnetic field measurement hamper such research efforts. Taking cognizance of this stalemate, the International Scientific Committee for Dense Magnetized Plasmas launched an initiative to address this state of affairs in an International Video Conference on 24th April 2020. This paper reports on the first experiments that resulted from that initiative