Numerical studies of driven, chirped Bernstein, Greene, and Kruskal modes

Recent experiments showed the possibility of creating long-lived, nonlinear kinetic structures in a pure-electron plasma. These structures, responsible for large-amplitude periodic density fluctuations, were induced by driving the plasma with a weak oscillating drive, whose frequency was adiabatically decreased in time fW. Bertsche, J. Fajans, and L. Friedland, Phys. Rev. Lett. 91, 265003 s2003dg. A one-dimensional analytical model of the system was developed fL. Friedland, F. Peinetti, W. Bertsche, J. Fajans, and J. Wurtele, Phys. Plasmas 11, 4305 s2004dg, which pointed out the phenomenon responsible for the modifications induced by the weak drive in the phase-space distribution of the plasma sinitially Maxwelliand. In order to validate the theory and to perform quantitative comparisons with the experiments, a more accurate description of the system is developed and presented here. The new detailed analysis of the geometry under consideration allows for more precise simulations of the excitation process, in which important physical and geometrical parameters ssuch as the length of the plasma columnd are evaluated accurately. The numerical investigations probe properties and features of the modes not accessible to direct measurement. Due to the presence of two distinct time scales sbecause of the adiabatic chirp of the drive frequencyd, a fully two-dimensional numerical study of the system is expected to be rather time consuming. This becomes particularly important when, as here, a large number of comparisons scovering a wide range of drive parametersd are performed. For this reason, a coupled one-dimensional, radially averaged model is derived and implemented in a particle-in-cell code. © 2005 American Institute of Physics. fDOI: 10.1063/1.1928251g