Spectral contents of electron waves under strong Langmuir turbulence

Abstract

In this work we present experimental results of electron plasma waves excited in a beam plasma system. Based on our experimental results we determine the transition from the quasi-linear to non-linear regime. We present the space evolution of the electron beam distribution function for both regimes. The spectrum of the electron plasma wave in the non-linear regime shows a component with frequency larger than the plasma frequency besides the plasma frequency itself. We show that the higher frequency component is strongly affected by Landau damping, indicating a dissipation region. The measured experimental power spectrum of this wave shows a dependence on wave number k given by W k ∝ k −7/2 as theoretically predicted.

Plasmon turbulence spectra with the filamentation patterns in a laser plasma

“…The strong Langmuir turbulence spectra have also been an active research area during the past few decades. [15][16][17][18][19][20] Experimental and simulation results suggest that the saturated spectrum should not be of a Kolmogorov type, but rather it possesses a combination of power-law and exponential dependence on the wave number. 9,18 However, most of these calculations are based on the incomplete Zakharov equations, 21 only involving the Langmuir and ion-sound waves.…”

Requirements for testing stochastic wave growth in laboratory plasmas using beam–plasma experiments

“…However, existing experiments on other devices have shown that launching such a beam is achievable. For instance, Alves et al used an adjustable beam with 0.1 v b /v b 0.2 and 5 × 10 −5 n b /n 0 10 −2 to study the transition from the quasilinear regime to the strong turbulence regime [20]. So launching a beam with the required parameters on WOMBAT appears feasible.…”