Department of Physics and Astronomy, Bartol Research Institute, University of Delaware, Newark, Delaware 19716, USA.
Phys Rev Lett. 2013 Sep 20;111(12):121105. doi: 10.1103/PhysRevLett.111.121105. Epub 2013 Sep 18.
Decay in time of undriven weakly collisional kinetic plasma turbulence in systems large compared to the ion kinetic scales is investigated using fully electromagnetic particle-in-cell simulations initiated with transverse flow and magnetic disturbances, constant density, and a strong guide field. The observed energy decay is consistent with the von Kármán hypothesis of similarity decay, in a formulation adapted to magnetohydrodyamics. Kinetic dissipation occurs at small scales, but the overall rate is apparently controlled by large scale dynamics. At small turbulence amplitudes the electrons are preferentially heated. At larger amplitudes proton heating is the dominant effect. In the solar wind and corona the protons are typically hotter, suggesting that these natural systems are in the large amplitude turbulence regime.
使用完全电磁粒子模拟，在具有横向流动和磁干扰、恒定密度和强引导场的情况下，研究了与离子动力学尺度相比大得多的无驱动弱碰撞动力学等离子体湍流随时间的衰减。观察到的能量衰减与 von Kármán 相似性衰减假说一致，这是一种适应磁流体动力学的表述。在小尺度上发生动力学耗散，但整体速率显然由大尺度动力学控制。在小的湍流动幅值下，电子优先被加热。在较大的幅值下，质子加热是主要效应。在太阳风和日冕中，质子通常更热，这表明这些自然系统处于大振幅湍流动态。
