The ablation dominated polymethylmethacrylate arc

High current density ( approximately 10 4 A cm -2 ) AC arcs in long confining tubes have been investigated experimentally and theoretically. A uni-dimensional arc model based on simplifying assumptions has been presented. The main energy transfer mechanism is via radiation to the bore surface, resulting in the heating, ablation and ionisation of the (C 5 H 8 O 2 ) which becomes the main plasma source. The ablation results in high measured pressures ( approximately 100 bars) in the tube central stagnation zone. It is shown that a two-zone arc develops, namely a hot core and a cooler sheath. Semi-empirical scaling formulae linking current density with field gradient, core temperature, sheath temperature and pressure have been derived. Effects of turbulence on the arc model are discussed.