Astrophysical reconnection and collisionless dissipation
Astrophysical reconnection and collisionless dissipation
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DOI：
10.1088/0741-3335/49/12b/s30
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发表时间：
2007-12
影响因子：
2.2
通讯作者：
J. Büchner
中科院分区：
文献类型：
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作者：
J. Büchner
磁场重联和无碰撞耗散是天体物理和聚变等离子体中常见的现象。虽然重联是造成聚变约束中断的原因，但它会在太阳和恒星、星系、行星磁层中引起耀斑爆炸，并导致宇宙中的极光和结构形成以及穿透磁边界。由于天体物理和聚变等离子体的弱耦合，耗散是由于集体现象，如等离子体波和微湍流，而不是直接的粒子-粒子碰撞。由于天体物理等离子体通常不能直接观测到，实验室研究可能有助于验证理论上的等离子体天体物理预测，但为了转移知识，必须考虑到天体等离子体的一些细节，它们的密度，温度，电流和磁场强度，几何形状甚至拓扑结构。作为一个例子，我们讨论的磁场重联在太阳日冕中，需要碰撞耗散。两者都是发生在完全不同尺度上的高度非线性过程。因此，我们参考数值模拟。最后，我们列出了等离子体天体物理学中最紧迫的开放问题，应在不久的将来解决。
Magnetic reconnection and collisionless dissipation are common phenomena of astrophysical and fusion plasmas. While reconnection is responsible for disruptions of a fusion confinement, it causes flare explosions at the Sun and stars, in galaxies, planetary magnetospheres, and it causes aurorae and structure formation in the Universe as well as penetration through magnetic boundaries. Due to the weak coupling in astrophysical and fusion plasmas, dissipation is due to collective phenomena such as plasma waves and micro-turbulence rather than direct particle–particle collisions. Since astrophysical plasmas usually are not directly observable, laboratory investigations may help to verify theoretical plasma astrophysical predictions but for the transfer of knowledge one has to take into account some specifics of astroplasmas, their density, temperature, currents and magnetic field strengths, geometry and even topology. As an example we discuss magnetic reconnection in the solar corona which requires collisionless dissipation. Both are highly nonlinear processes that occur at totally different scales. Hence, we refer to numerical simulations. Finally, we list the most urgent open questions in plasma astrophysics which should be addressed in the near future.