Abstract:

For original paper see Zambreanu and Doloc, ibid., vol. 34, p. 1433 (1992). Zambreanu and Doloc presented an electrodynamic model for describing the electric and magnetic fields of a plasma focus discharge during the last stages of the current sheath (CS) evolution. Two different geometries were considered: a hollow cylindrical current distribution (of external radius rs and thickness Delta r) for the CS collapse phase, and a homogeneous column for the pinch phase. In both cases, a uniform current density j, in the layer and infinite column length was assumed. While explicit expressions for the axial component Az of the magnetic vector potential (in terms of r s, Delta r, the turning radius R0 of the CS, the cylindrical radial coordinate r and the discharge current I) were presented, the corresponding expressions for the scalar potential Phi were not given and thus the evaluation of the axial electric field Ez remained implicit. However, generic profiles of the fields were shown in the paper for both the hollow phase of the CS and the solid column phase. Kelly and Marquez analyse the column phase of the CS but the results can be extended to the hollow phase without difficulty.