Equation of State for Hydrodynamic Compression in Turbulent Z-Pinch

Princeton University, Princeton NJ

Investigators

Abstract

This project investigates the speculative possibility of storing energy in turbulent fluid eddies, and then suddenly releasing this energy. When gas is compressed, its temperature increases. However, the increase in temperature might be less if there are other degrees of freedom that absorb the energy. Suppose, for example, that the gas energy resides mainly in whirling eddies, rather than in completely random motion. We ask the question whether there are conditions under which compression of the gas might increase this eddy energy. The significance of this question is that energy in eddies acts differently than random energy because neighboring molecules tend to move in the same direction. That means that there would be fewer times that gas molecules would make high-impact head-on collisions. Important processes such as nuclear fusion depend on this relative motion, so the fusion reactions would be fewer in gases where the energy resides in whirling eddies rather than in random thermal motion. If this were true, then one might also speculate that the effect could be used advantageously in controlling nuclear fusion in a highly compressed plasma. This project investigates the possibility of storing and then suddenly releasing the energy that can be deposited into turbulent fluid eddies in a plasma. It is conjectured that, under compression on a time scale in which viscosity may be neglected, the energy in such eddies might increase. Also, if the energy resides in hydrodynamic eddies rather than ion temperature, it means that it is unavailable to electrons through collisions. Thus, this energy cannot be easily captured by electrons and radiated. If the compression increases eddy energy more than the random energy, a new paradigm for storing energy in a highly compressed plasma might be advanced in which the energy content is increased under compression in a non-radiating plasma, and then suddenly released under viscous dissipation. To test these speculations, particle-in-cell simulations will be performed to describe compressing turbulent eddies, with guidance obtained from Z-pinch experiments that already appear to exhibit certain features of a turbulent inviscid plasma. This work will involve a collaboration between Princeton University and the Weizmann Institute of Science in Israel, and will be performed under the umbrella of the Memorandum of Understanding on Research Cooperation between NSF and the US-Israel Binational Science Foundation. This project is co-sponsored by the NSF's Physics Division and the Office of International Science and Engineering.