论文标题

电磁波的排放为高$β$制度中非线性无碰撞电离波的停止机制

Emission of electromagnetic waves as a stopping mechanism for nonlinear collisionless ionization waves in a high-$β$ regime

论文作者

Mao, Haotian, Weichman, Kathleen, Gong, Zheng, Ditmire, Todd, Quevedo, Hernan, Arefiev, Alexey

论文摘要

嵌入中性气体中的高能量密度等离子体能够发射捕获能量电子的外部传播非线性静电电离波。该捕获保持强大的护套电场,从而在磁场电离的帮助下,可以快速和持久的波传播。使用1D3V动力学模拟,我们检查了在存在横向MG级磁场的情况下电离波的传播,其目标是在等离子体的初始热压超过磁场压力的情况下确定定性变化($β> 1 $)。我们的关键发现是,磁场通过引起维持波的能量电子而通过发出电磁波来损失其能量,从而阻止了传播。发射伴随着从血浆中驱动磁场,并增加了诱捕波结构的电子损失。所描述的效果提供了一种机制,可缓解涉及嵌入等离子体的应用,例如激光辐照的氘气喷头的高流量中子产生。

A high energy density plasma embedded in a neutral gas is able to launch an outward-propagating nonlinear electrostatic ionization wave that traps energetic electrons. The trapping maintains a strong sheath electric field, enabling rapid and long-lasting wave propagation aided by field ionization. Using 1D3V kinetic simulations, we examine the propagation of the ionization wave in the presence of a transverse MG-level magnetic field with the objective to identify qualitative changes in a regime where the initial thermal pressure of the plasma exceeds the pressure of the magnetic field ($β>1$). Our key finding is that the magnetic field stops the propagation by causing the energetic electrons sustaining the wave to lose their energy by emitting an electromagnetic wave. The emission is accompanied by the magnetic field expulsion from the plasma and an increased electron loss from the trapping wave structure. The described effect provides a mechanism mitigating rapid plasma expansion for those applications that involve an embedded plasma, such as high-flux neutron production from laser-irradiated deuterium gas jets.

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