**吉原総 氏 **

**2017年7月27日(木) 15時00分**

**総合研究10号館317号室(セミナー室)**

The Vlasov equation is a partial differential equation describing temporal evolution of a long-range Hamiltonian system in the limit of large population. We inject two successive pulses at the time t=0 and τ into a stable stationary state of the Vlasov equation. If the stationary state is spatially homogeneous and the two pulses satisfy a certain condition, it is known that the pulse responses can appear not only at t=0 and τ but also at t=2τ, 3τ and so on. This phenomenon is called echo. However, do echoes happen when the stationary state is spatially inhomogeneous, and then is it necessary that the two pulses satisfy the above condition? We consider these problems in general spatially one-dimensional Vlasov systems.

Last modified: Tue Jul 25 18:32:09 JST 2017