Three-dimensional electromagnetic strong turbulence: II. Wave packet collapse and structure of wave packets during strong turbulence

Large-scale simulations are performed by numerically solving the three-dimensional (3D) electromagnetic Zakharov equations, focusing on individual wave packet collapses and on wave packets forming in strong turbulence. The structures of the Langmuir, transverse, and total electric field components of wave packets during strong turbulence are investigated over a range of $v_{e}/c$. For $v_{e}/c < 0.17$ strong turbulence is approximately electrostatic and wave packets have very similar structure to purely electrostatic wave packets. For $v_{e}/c > 0.17$ transverse modes become trapped in density wells and contribute significantly to the structure of the total electric field. At all $v_{e}/c$ the Langmuir energy density contours of wave packets are predominantly oblate. The transverse energy density contours of wave packets are predominantly prolate, with the major axis being perpendicular to the major axes of the Langmuir component. This results in wave packets becoming more nearly spherical as $v_{e}/c$ increases, and in turn generating more spherical density wells during collapse.