Universal turbulence scaling law -8/3 at fusion implosion

TL;DR

This paper proposes a universal turbulence energy spectrum with a -8/3 scaling law for fusion implosion turbulence, offering a new perspective that differs from the traditional Kolmogorov spectrum, and discusses its physical mechanism.

Contribution

It introduces a new universal turbulence scaling law of -8/3 based on solutions of Euler equations, relevant to compressible turbulence in fusion implosion.

Findings

The -8/3 spectrum better fits simulation results than Kolmogorov -5/3.

The spectrum is linked to hydrodynamic instability of rotation behind shock waves.

A possible mechanism for anisotropic spectrum formation is proposed.

Abstract

The new interpretation of the known results of simulation of the turbulent regime at the time before stagnation stage of the fusion implosion is stated. For this aim the universal turbulence energy spectrum obtained by the authors with a scaling law -8/3, which corresponds to the exact solution of one-dimensional Euler equations for the dynamics of a compressible medium, is used. It is stated that the scaling law -8/3 has more relevance in comparison with the Kolmogorov spectrum of -5/3 in the inertial sub-range of scales for the compressible turbulence at this stage of fusion implosion. A possible mechanism for the occurrence of the anisotropic spectrum -8/3 in turbulence associated with hydrodynamic instability of the rotation of the medium behind the shock wave front is considered.