A comparison of weak-turbulence and particle-in-cell simulations of weak electron-beam plasma interaction

Abstract

Quantitative comparison of reduced-description particle-in-cell and quasilinear-Zakharov models for parametrically excited Langmuir turbulence Quasilinear theory has long been used to treat the problem of a weak electron beam interacting with plasma and generating Langmuir waves. Its extension to weak-turbulence theory treats resonant interactions of these Langmuir waves with other plasma wave modes, in particular, ion-sound waves. These are strongly damped in plasma of equal ion and electron temperatures, as sometimes seen in, for example, the solar corona and wind. Weak turbulence theory is derived in the weak damping limit, with a term describing ion-sound wave damping then added. In this paper, we use the EPOCH particle-in-cell code to numerically test weak turbulence theory for a range of electron-ion temperature ratios. We find that in the cold ion limit, the results agree well, but for increasing ion temperature the three-wave resonance becomes broadened in proportion to the ionsound wave damping rate. Additionally, we establish lower limits on the number of simulation particles needed to accurately reproduce the electron and wave distributions in their saturated states and to reproduce their intermediate states and time evolution. These results should be taken into consideration in, for example, simulations of plasma wave generation in the solar corona of Type III solar radio bursts from the corona to the solar wind and in weak turbulence investigations of ion-acoustic lines in the ionosphere. V C 2014 AIP Publishing LLC.

Self-consistent particle-in-cell simulations of fundamental and harmonic plasma radio emission mechanisms

“…Umeda (2010) reported that increasing pseudoparticle numbers diminished the signal associated with harmonic emission. Under-resolved particle numbers could contribute to excessive noise on the EM dispersion curves (and be mis-interpreted as emission as per the first point) and also result in poor replication of physical time-scales as per Ratcliffe et al (2014) and Lotov et al (2015). Finally, all of the previous works consider systems with high beam-to-background density ratios (all take n b /n 0 > 1%) and are so in the strong beam regime.…”

Investigation of beam-plasma instability in charged plasma in the absence of ions

“…Such behavior of the distribution function is inherent to the process of electron beam relaxation during the beam-plasma instability development in the electron-ionic plasmas. 44,45…”

New soliton solutions of the system of equations for the ion sound and Langmuir waves

“…A. Zavlavsky et al have presented spatial localization of Langmuir waves [20]. Also, Langmuir wave spectral energy densities have been derived from the electric field and compared to the weak turbulence results by H. Ratcliffe et al [21]. We introduce the system of equations for the ion sound wave under the action of the ponderomotive force due to high-frequency field and for the Langmuir wave [22]…”