...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Two-dimensional hybridmodels of H~+-He~(++) expanding solar wind plasma heating
【24h】

Two-dimensional hybridmodels of H~+-He~(++) expanding solar wind plasma heating

机译：二维hybridmodels H ~ +他~ (+ +)扩大太阳风等离子体加热

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Preferential heating and acceleration of the solar wind He~(++) ions compared to protons in fast solar wind streams have been known for decades, thanks to in situ spacecraft measurements at 0.29–5 AU. Turbulent magnetic field fluctuations with approximate power law spectra have been observed as well. However, the exact causes of these processes are still not known due to the lack of detailed information on the magnetic field fluctuations and ion velocity distributions in the acceleration region of the solar wind. Here the collisionless heating processes in expanding solar wind plasma are investigated using 2-D hybrid modeling with parameters appropriate to the heliocentric distance of 10 R_S. In this study the ion dynamics is described kinetically, while electrons are treated as a background massless fluid in an expanding solar wind model. The source of free energy for the heating is introduced through an initial nonequilibrium state of the plasma with large He~(++) ion temperature anisotropy or with super-Alfvénic relative ion drift. We also employ an externally imposed spectrum of magnetic fluctuations in the frequency range below the proton gyroresonant frequency to heat the He~(++) ions. We investigate the effects of solar wind radial expansion by modeling several values of the expansion rate in a parametric study. We find that the preferential ion heating is attained in both nonexpanding and expanding solar wind models. Thus, the expansion has little effect on the preferential He~(++) ion heating by the processes considered here. Moreover, the expansion leads to faster evolution of the magnetosonic drift instability, reducing the drift velocity to lower values sooner, and the corresponding generation of the magnetic fluctuations that heat the ions, compared to the nonexpanding case. This is due to the reduction of the perpendicular particle velocities in the expanding (inflated) frame. For cases with little proton perpendicular heating, the solar wind expansion leads to the reduction of the proton temperature anisotropy to values less than one in the low-β_(p∥) solar wind acceleration region consistent with some observed values. However, this effect must be offset by perpendicular proton heating—likely by the same process that heats the He~(++) ions to be consistent with the full range of observed proton perpendicular temperature values.
机译：优惠供暖和太阳能的加速度风他~(+ +)离子质子相比快太阳风流已经知道了几十年,由于原位航天器测量0.29 - 5。与近似幂律谱观察到的。由于这些过程仍然是未知的缺乏详细信息磁场波动和离子速度分布加速地区的太阳风。这里的无碰撞的加热过程太阳风等离子体进行扩张使用二维混合建模与参数适当的日心距离10R_S。被视为一个活动,而电子背景无质量的液体在一个扩大太阳能风模型。通过初步介绍了加热非平衡态等离子体的大他~(+ +)离子温度各向异性或super-Alfvenic相对离子漂移。磁的外部强加的频谱波动的频率范围以下质子gyroresonant频率加热他~ (+ +)离子。径向扩张通过建模几个值膨胀率的参数研究。的离子加热获得优惠nonexpanding和太阳风扩张模型。优惠他~(+ +)离子加热的过程被认为是在这里。扩张导致更快的发展magnetosonic漂移不稳定性,减少了漂移速度更快更低的值,相应的代磁波动热离子,相比nonexpanding情况。垂直的粒子的速度扩大(膨胀)框架。太阳风质子垂直加热扩张导致质子的还原温度各向异性值小于1低-β_ (p∥)太阳风加速地区与一些观测值一致。这种效果必须垂直所抵消质子heating-likely通过同样的过程热他~(+ +)离子是一致的全方位的观察质子垂直温度的值。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号