FORMATION OF A SPHEROMAK-LIKE MAGNETIC-CONFIGURATION BY A PLASMA-FOCUS SELF-TRANSFORMED MAGNETIC-FIELD

Experimental results are presented that verify the formerly predicted possibility of the formation of a closed spheromak-like magnetic confi guration (SLMC) by the natural magnetic field of a plasma focus discha rge. The model is based on the self-generated transformation of a toro idal (i.e., azimuthal) magnetic field into a poloidal one. At the fina l stage of the discharge, the SLMC takes the form of a squeezed sphero mak, which includes a combined Z-theta-pinch at its major axis, exhibi ting a power density several orders of magnitude larger than that meas ured experimentally on a force-free flux-conserver-confined spheromak formed by helicity injection. The results suggest the possibility of f urther concentrating the plasma power density by means of compressing the SLMC-trapped plasma by the residual magnetic field of the plasma f ocus discharge. A qualitative model is given for the scenario of the S LMC-producing plasma focus discharge. Special emphasis is placed on th e difference of this approach front conventional approaches to the rol e of magnetic field reconnection processes in plasma focus dynamics. T he operational conditions necessary to stimulate SLMC formation in hig h-current gaseous discharge systems and the uses of SLMC-trapped plasm as are discussed briefly.