Dimensionless similarity invariants and criteria of cylindrical Z-pinch compression regimes in a gas

A dimensionless equation containing two dimensionless complexes Z and d 0 was derived from the consideration of the energy balance at the early stage of cylindrical Z -pinch development in a gas. The requirement of the equation invariance under the transformation of stretching (compression) of coordinates and time imply that the Ξ and d 0 complexes are dimensionless similarity invariants of the indicated discharge. These invariants were shown to be quantitative criteria of realization of single, double, triple, etc. cylindrical Z -pinch plasma column compression regimes.