A novel regime of the saturation of the Pierce-type ion-sound instability in bounded ion-beam-plasma system is revealed in 1D PIC simulations. It is found that the saturation of the instability is mediated by the oscillating virtual anode potential structure. The periodically oscillating potential barrier separates the incoming beam ions into two groups. One component forms a supersonic beam which is accelerated to an energy exceeding the energy of the initial cold ion beam. The other component is organized as a self-consistent phase space structure of trapped ions with a wide energy spread - the ion hole. The effective temperature (energy spread) of the ions trapped in the hole is lower than the initial beam energy. In the final stage the ion hole expands over the whole system length.

中文翻译：

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有界等离子体中离子声不稳定性饱和时的自加速和能量通道

一维 PIC 模拟揭示了有界离子束等离子体系统中皮尔斯型离子声不稳定性饱和的新机制。发现不稳定的饱和是由振荡的虚拟阳极电位结构介导的。周期性振荡的势垒将进入的束离子分成两组。一个组件形成超音速束，该束被加速到超过初始冷离子束能量的能量。另一个组件被组织成一个自洽的相空间结构，由具有广泛能量分布的俘获离子组成 - 离子空穴。被困在空穴中的离子的有效温度（能量传播）低于初始束能量。在最后阶段，离子孔扩展到整个系统长度。