Optimization of a Hybrid Gas-Puff with Outer Plasma Shell for Efficient Generation of Neon K-Shell Radiation in the Microsecond Implosion Regime

Abstract

A new type of a Z-pinch load, a hybrid gas puff with an outer plasma shell, has been tested successfully in the experiments on the GIT-12 generator (4.7 MA, 1.7 μs) in the Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, for generation of the argon K-shell radiation [1, 2]. It is of interest to study this load using various substances as an emitter. This paper presents the results of experiments with neon. An analysis of experimental data on radiation generation in argon K-lines showed that the maximum efficiency of a plasma radiation source is achieved when argon is localized in the central region of the load unit and does not spread to the periphery, interacting with the outer deuterium shell. This allowed the most efficient load configuration to be directly applied in experiments with neon. The inner neon cascade, which played the role of an emitter, was a solid gas jet with a small initial diameter on the axis of the system. The outer deuterium cascade was a hollow gas shell and acted as an implosion stabilizer. The third component was a hollow plasma shell injected at a large initial radius, providing initial conductivity and the formation of a uniform current layer. In these experiments, the diameter of the inner neon jet was 10 mm, the diameter of the annular deuterium shell was 81 mm, and the outer plasma shell was generated by 48 plasma guns located at a diameter of 350 mm. The parameters of the deuterium and plasma shells that ensure stable implosion at times of the order of microseconds were determined in earlier experiments [3] and were not changed during the research. The linear mass of the neon jet varied in the range from 150 to 450 μg/cm with a step of 50 μg/cm; the injection time was ∼300 μs. The maximum radiation yield in neon K-lines was achieved at a neon mass of 450 μg/cm and exceeded 17 kJ/cm at a peak implosion current of 2.85 MA. Compared to the double shell neon gas puff with an outer plasma shell [4], the hybrid load demonstrated better efficiency, since in those experiments the maximum neon K‑shell radiation yield (14.7 kJ/cm) was achieved at a higher peak implosion current (3.5 MA).