High energy concentration by symmetric shock focusing

Authors: Apazidis, N., Kjellander, M. K., Tillmark, N.T.
Document Type: Conference
Pubstate: Published
Journal: Proceedings of the 28th International Symposium on Shock Waves held in Manchester UK, 17 to 22 July 2011, Vol 2
Volume: 1   99-104
Year: 2012


Extreme energy concentrations in gas are achieved experimentally in a specially constructed shock tube facility at KTH Mechanics. The high energy concentration is manifested by a formation of a hot, light emitting gas core. Experimental, numerical and theoretical investigations show that the shape of the imploding shock is of pivotal importance for the final energy concentration. Cylindrical shocks are unstable. Symmetric polygonal shocks are shown to be dynamically stable and are produced by various methods, e.g. thin wing profiles placed radially in the test section. Such symmetric polygonal shocks are able to produce extremely high energy levels at the focal point. Spectral data from 60 ns short intervals of 8 microsecond light pulse give temperatures in the range of 6000 K.