Explosion of electric cables under water to understand the shock waves

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If you are not a physicist specializing in plasmas, the explosion of electrical wires under the water may seem like a bad idea. But it is actually a way of studying shock waves, disturbances that propagate, that move faster than the speed of sound.

Shock wave studies allow researchers to realize the dense and warm matter found only in extreme conditions around stars and created in the laboratory for research on inertial confinement fusion. Shockwaves also have medicinal, industrial and military applications. Exploding an underwater wire is a means of generating a shock wave and giving scientists a tool to check the equations used to predict shock waves.

Researchers at the Technion Israel Institute of Technology have attempted to understand the relationship, if any, between the evolution of a shock wave and the expansion of the exploding wire in a recent newspaper article. Physics of plasmas, from AIP Publishing. Taking images in shaded lines to see the trajectory of the shock waves, they found that the expansion of the wire determines the decay of a shock wave and developed a simplified model to describe this relationship.

Researchers have observed that long after shockwave generation, the wire continues to expand, resulting in a significantly slower shock wave than predicted by previous models. In addition, unlike previous models, this new model does not assume a similar movement and an instantaneous release of energy.

"Surprisingly, and this is what is exciting, the results of this simplified model perfectly match the results obtained experimentally," said Alexander Rososhek, author of the paper. Experience has shown that the exploding wire that generates the shock wave expands at a subsonic speed.

"This result, combined with one-dimensional hydrodynamic simulations, has allowed us to understand in depth the transient process governing the generation of shock waves," said Rososhek, "and to advance our knowledge of shock wave generation in its together".

More specifically, these results apply to different experimental setups to study shock waves. For example, the results of this research can be used in experiments where the intensity of the shock is amplified by a flow of water acquiring additional energy by burning the exploded wires.

In future research, Rososhek and other article authors will attempt to increase the intensity of shockwaves by modifying the properties of the exploding wire, which could provide a deposit of energy additional. They would also like to use a high intensity x-ray beam, of the order of one picosecond, to study the initial phase of shock generation, thanks to a joint work led by Simon Bland's group of researchers. Imperial College of London with the European Synchrotron Radiation Facility.