Composite pinch on GIT-4

First experiments with exploding wires (EW) showed that the time of the energy input in a wire, t/sub E/, was of crucial importance for elimination of different pinch inhomogeneities. At the same time, practically realized current drivers (t/sub E//spl Gt/10 ns) still do not allow avoidance of coronal expansion and recompression of the wire plasma and, hence, instabilities formation. In order to sharpen the energy input time it was proposed to use intermediate conversion of the electromagnetic energy into kinetic energy of an accelerated plasma shell. This approach evoked considerable progress in maximizing the radiation power of Z-pinches. Further development of the liner systems was seen in fast collisions of accelerated liners onto targets, such as in double-liner or plasma-on-wire (POW) configuration. In particular, the POW scheme was shown to be rather perspective in obtaining more homogeneous plasma radiation source (PRS). Stable external shell implosion was initially thought to be necessary but hardly achievable point in the POW. The paper aims to advance a concept of the Composite Pinch (CP, or C-pinch) in which a controlled shell instability leads to successive decrease of t/sub E/ that results in improved PRS properties. Discussed model describes general principles of C-pinch formation and defines the limits of its application. The model correlates with the experimental results from GIT-4 generator. The main results demonstrate higher hard X-ray power to be produced by a high-temperature/density uniform plasma.