  Recent experiments using 15 frame interferometry on PF-1000 facility in
Warsaw confirm the association between neutron emission and spontaneously
self-organized, relatively long lasting, finite plasma structures. A crucial
aspect of this association is the simultaneous observation of an axial magnetic
field, which can allow magnetic flux lines to densely cover closed surfaces
creating "magnetic flux surfaces". Evolution of such 3-dimensional (3-D)
magnetic field structures is necessarily accompanied by induced electric field
that can provide a very long (theoretically infinite) acceleration path length
along a trajectory enclosed within the magnetic structure leading to high ion
kinetic energy, resulting in a high reaction rate. Associated charge and
current densities can be related to electric scalar potential and magnetic
vector potential measured outside the plasma. We report our first observations
of these fields outside the plasma focus and discuss their general features.
The reported technique is capable of unambiguous first-principles
interpretation of signals in terms of quantities related to distributions of
charge density and rate of change of azimuthal current density
("electromagnetic structure") in the plasma focus. It is non-intrusive and
completely insensitive to non-axisymmetric aspects of plasma. Our first results
show that axial magnetic field generated by azimuthal current density
distribution symmetric about the axis exists before, during and after the pinch
phase.
