Evolution of the Pinched Column During Hard X-ray and Neutron Emission in a Dense Plasma Focus

Characteristics of fast deuteron sources generated in a dense plasma focus

“…They were used Fig. 1 Scheme of the diagnostics arrangement: 1-scintillation detectors, 2-films recording the interferometric frames, 3-PIN detector of X-rays, 4-soft X-ray framing camera, 5-Ag-activation detectors of fusion neutrons, 6-ion pinhole cameras, 7-X-ray pinhole camera to determine instants of the emission of hard X-rays (HXRs are produced by fast electrons during their collisions with the electrodes and chamber walls [17]) and fusion-produced neutrons and to estimate a mean energy of these neutrons (and the primary deuterons) by means of a time-of-flight method, as described in a paper [35]. The HXRs were filtered by the stainless steel wall of the experimental chamber, which was (1-2) cm in thickness and absorbed radiation up to 100 keV.…”

“…Numerous PF discharges with the deuterium filling, which were devoted to the studies of plasma transformations and fusion neutrons production, have been studied within a PF-1000 mega-ampere facility at the IPPLM in Warsaw, Poland, during the recent decade [14][15][16][17][18][19][20]. Space-and time-resolved measurements with a laser interferometer showed the appearance and evolution of various toroidal and plasmoidal structures.…”

“…The appearance of the closed currents was deduced (on the one hand) from measurements performed with magnetic probes, which showed the existence of a self-generated axial component of the local magnetic field [21,22]. On the other hand, the knowledge of the plasma density distribution and local temperatures (at the assumption of the quasi-stationary conditions) made it possible to estimate the plasma pressure gradient, which can be explained by a distribution of the force density (j × B) and consequently by the distribution of the currents and their magnetic fields [17,20]. The closed currents and associated magnetic fields are generated at transformations of a portion of the kinetic energy of the pinched current sheath by a magnetic dynamo effect.…”

“…This evolution produces the magnetic turbulences, and it leads to the formation of larger ordered structures [23]. They are initially toroidal ones with the dominant toroidal current and poloidal magnetic field, which later on are transformed into a plasmoid of a spheromak-like configuration of the local magnetic field [17,20]. Their internal high pressure, at the electron temperature of (50-70) eV and a plasma density of (10 24 -10 25 ) m −3 , can be balanced by the pinching pressure of the discharge current.…”