arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1706.05660physics.plasm-ph
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极端驱动离子声波

Extreme driven ion acoustic waves

Lazar Friedland, Arkadiy Shagalov

摘要:

讨论了啁啾驱动下从平凡平衡态激发大振幅强非线性离子声波。在一定条件下,该系统通过线性共振后,非线性和参数的变化协同作用,通过激发离子声波在其参数空间的偏移,保持与驱动波的锁相,产生受控的振幅增长。我们研究这些自共振波通过一个完全非线性的温暖的流体模型和预测形成尖锐的峰值(极端)离子声激发与本地离子密度显着超过未扰动的等离子体密度。驱动波振幅受动力学波破碎的限制,因为波的局部最大流体速度接近驱动的相速度。采用Vlasov-Poisson模拟验证了流体模型的结果,并应用Whitham平均变分原理分析了自共振离子声波的演化过程。

英文摘要:

Excitation of large amplitude strongly nonlinear ion acoustic waves from a trivial equilibrium by a chirped frequency drive is discussed. Under certain conditions, after passage through the linear resonance in this system, the nonlinearity and the variation of parameters work in tandem to preserve the phase-locking with the driving wave via excursion of the excited ion acoustic wave in its parameter space, yielding controlled growth of the wave amplitude. We study these autoresonant waves via a fully nonlinear warm fluid model and predict formation of sharply peaked (extreme) ion acoustic excitations with local ion density significantly exceeding the unperturbed plasma density. The driven wave amplitude is bounded by the kinetic wave-breaking, as the local maximum fluid velocity of the wave approaches the phase velocity of the drive. The Vlasov-Poisson simulations are used to confirm the results of the fluid model and the Whitham's averaged variational principle is applied in analyzing evolution of the autoresonant ion acoustic waves.

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