Z-pinch research in France an overview over 4 décades (1976-2016)
Résumé
The Z-pinch (ZP) is a rather unique source of dense, hot, transient plasma which has attracted interest early, in the quest for fusion. France has participated to this effort in few national Institutions and has developed a renowned expertise in pulsed power science and technology. After recalling the physical background, we will give a chronological presentation of case studies. ZP machines were built in French labs, Atomic Energy Commission, Armament Agency and Ecole Polytechnique for larger ones, as well as in universities with compact devices. For each we will describe the performances and the main scientific achievements. The research has been mainly oriented to the generation of copious doses of x-rays. Based on theoretical considerations, drawbacks were expected from some instabilities growing during the compression. Thus, Z-pinch stabilization was a major issue and was addressed by various techniques: gas-puff profiling, staged ZP, Bz, plasma puff, plasma on wire, composite ZP. In general, the generators were based on capacitive storage but a strong effort was done of inductive storage. Moreover, the work in France has been strongly connected to other Z-pinch programs in the UK, in Russia and in the USA and a number of joint experiments were performed. Selected results of these cooperative works will be given too. Last but not least, we will conclude by new trends. The laboratory has contributed to introduce innovative approaches of the load, supported by complete numerical simulations. They are currently tested, even used routinely, on world-class generators : load current multiplier, flat array ZP, multiple-ZP hohlraum.