We investigate the nonlinear wave-particle interaction using a many-body (finite-N) description. In optics and plasma physics, this description has long been deemed impractical to model whole experiments due to its excessive number of degrees of freedom. To bypass this difficulty, we developed a reduced model validated for periodical structures, such as traveling-wave tubes, gyrotrons, free-electron lasers,of particle accelerators.
This approach is combined with a self-consistent hamiltonian in one space dimension to model the momentum exchange between fields and particles. From it, we build a symplectic integrator in time domain in order to reproduce wave coupling, field distortions, turbulence and chaos from the nonlinear dynamics of particles. Our numerical tool is validated against measurements from several industrial (15cm long) traveling-wave tubes with various geometries. Thanks to the drastic reduction of degrees of freedom, simulations are 200 to 500 times faster than alternative particle-in-cell codes for the same accuracy.
This enables us to investigate microseconds long effects (telecom signals, chaos) while the particle dynamics require picoseconds timesteps. Besides current industrial applications, we also adapt the model to the 4m long traveling-wave tube used at PIIM laboratory, Aix-Marseille University-CNRS, with which Landau damping and hamiltonian chaos have been observed.
1. D. F. G. Minenna et al., Europhys. Lett. 122, 44002 (2018).
2. D. F. G. Minenna et al., IEEE Trans. El. Dev. 66, 4042-4047 (2019).
| Subject : | : | poster |
| Topics | : | Dynamical Systems |
| Keywords | : | Wave particle interaction ; Time domain numerical model |
| PDF version | : |  PDF version |
