Fusion Plasma Focus

Pulsed plasmas containing hydrogen isotopes can produce bursts of alpha particles and neutrons as a consequence of nuclear reactions. The neutrons are useful for radiation-effects testing and for other materials research. A dense plasma focus filled with deuterium at low pressure has produced 10 neutrons in a single pulse (76) (see Deuterium AND TRITIUM). Intense neutron fluxes also are expected from thermonuclear fusion research devices employing either magnetic or inertial confinement. 

Yousefi H R, Nakada Y, Ito H and Masugata K (2003), Investigation of the neutron production mechanism in a 20 kJ plasma focus device . Journal of Fusion Energy, 25,245-248. 

The field of PWl is challenging, multifaceted, and highly interdisciplinary. It comprises research fields such as plasma physics, surface physics, solid-state physics, atomic and molecular physics, nuclear physics, chemistry, materials science, and mechanical engineering. In the following, focus will be put on the PSI processes at the plasma-facing surfaces, because they are of special importance for the operation of fusion plasmas. The selection of a specific plasmafacing material is closely linked to the operational scenario of the plasma and vice versa. Some other aspects of PWl will shortly be presented at the end of this section. Basic questions related to plasma-material interaction in magnetically confined fusion are discussed in the textbook of Naujoks (2006). 

Leopoldo Soto, (2005)New trends and future perspectives on plasma focus research, Plasma Physics and Control Fusion, 47,361-381... 

The name Plasma Focus (PF) has been bestowed upon a development of the fast dynamic Z-pinch characterized by a new type of electrode configuration which lends itself to the production of a non-cylindrical implosion of the current sheath. It produces a short lived, rather dense plasma, whose properties are dominated by the occurrence of macroscopic and microscopic instabilities. The fame of the PF has long been based essentially on the fact that it was the most intense neutron producing device in the field of controlled thermonuclear research. Moreover, the neutron yield has the remarkable property of scaling as the second power of the energy IVo stored in the capacitor bank. The question of the character of the neutron spectra of the PF correlated to the neutron production mechanism, has long cast fundamental doubts on the relevance and interest of developing further this line of research for applications in the field of controlled fusion. 

Bilbao, L., Bruzzone, H., Nikulin, V., Rager, J. P., Plasma dynamics during neutron production in the Frascati 1 MJ Plasma Focus devicey Associazione EURATOM-CNEN sulla fusione. Report 80.11. 

Some results of the Plasma Focus studies performed in the Kurchatov Institute and the Lebedev Institute in Moscow will be presented, while some possible applications of Plasma Focus systems for controlled fusion purposes will be discussed. 

Despite great strides, the problems arising from plasma-material interactions (PMIs), together with the selection of plasma facing materials, still represent major challenges for the reliable and safe operation of a D-T next-step tokamak [1]. They also remain potential obstacles for the successful development of future fusion power reactors. These issues came into sharp focus during D-T operation of the Tokamak Fusion Test Reactor (TFTR) and the Joint European Torus (JET) and, in particular, in the process of designing ITER. 

Decomposition involves the liberation of the analyte (metal) of interest from an interfering matrix by using a reagent (mineral/oxidizing acids or fusion flux) and/or heat. The utilization of reagents (acids) and external heat sources can in itself cause problems. In elemental analysis, these problems are particularly focused on the risk of contamination and loss of analytes. It should be borne in mind that complete digestion may not always be required as atomic spectroscopy frequently uses a hot source, e.g. flame or inductively coupled plasma, which provides a secondary method of sample destruction. Therefore, methods that allow sample dissolution may equally be as useful. 

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