Kinetic simulations of ladder climbing by electron plasma waves

Abstract

The energy of plasma waves can be moved up and down the spectrum using chirped modulations of plasma parameters, which can be driven by external fields. Depending on whether the wave spectrum is discrete (bounded plasma) or continuous (boundless plasma), this phenomenon is called ladder climbing (LC) or autoresonant acceleration of plasmons. It was first proposed by Barth et al. [Phys. Rev. Lett. 115, 075001 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.075001] based on a linear fluid model. In this paper, LC of electron plasma waves is investigated using fully nonlinear Vlasov-Poisson simulations of collisionless bounded plasma. It is shown that, in agreement with the basic theory, plasmons survive substantial transformations of the spectrum and are destroyed only when their wave numbers become large enough to trigger Landau damping. Since nonlinear effects decrease the damping rate, LC is even more efficient when practiced on structures like quasiperiodic Bernstein-Greene-Kruskal (BGK) waves rather than on Langmuir waves per se.

Ladder climbing and autoresonant acceleration of the spherical plasma density wave

“…We note that, the effects of the Landau damping in the system should be considered due to the collisionless dissipation is not contained in our fluid equations, and which may cause the energy loss at high mode number [19]. If Maxwellian distribution is assumed, the local Landau damping rate for the mth mode is given by [25,26].…”

“…Obviously, Ξ m grows rapidly with m, hence, the value of m must be restricted in order to guarantee our model is still valuable. Specifically, the maximum mode m max should satisfy m max m kin in the system, where m kin is defined as Ξ m ∼1 [18,19].…”

“…Compared with AR, the discrete nature of LC is visible only when spectra of the systems is discrete enough, therefore, it is studied only in quantum systems including anharmonic oscillators [13][14][15], Rydberg atom [16] and bouncing neutrons [17]. Interestingly, it is demonstrated that classical systems, for example, Langmuir waves in bounded plasma, also can exhibit LC much like a quamtum system [18,19]. This is the first report about the LC phenomenon of the classical system and it has a significant impact on the acceleration and manipulation of the electrons.…”

“…However, the prediction of the LC and AR in the classical plasma system given by [18,19] is based on a onedimensional plasma model in terms of the energy of the electrons. Obviously, to describe the general and real problems, considering the case of the higher dimension is urgent, particularly, for the spherical plasma wave.…”

Quantum versus classical dynamics in the optical centrifuge

“…In contrast, in the quantum limit, the system undergoes successive Landau-Zener (LZ) transitions [15,16], or quantum ladder climbing (LC). Both regimes of operation were demonstrated and used in atoms and molecules * lazar@mail.huji.ac.il [17][18][19][20][21], anharmonic oscillators [14], Josephson junctions [22], plasma waves [23,24], and cold neutrons [25]. An interesting and surprising effect in some driven chirped anharmonic oscillators is the forced dynamical transition from the quantum to the classical regime [26].…”