离子非线性极化漂移对动力学Alfvér孤波特性的影响

THE INFLUENCE OF ION'S NONLINEAR POLARIZATION DRIFT ON THE CHARACTER OF SOLITARY KINETIC ALFVEN WAVE

考虑离子极化漂移中非线性项对动力学Alfven孤波特性的影响,采用双流体模型研究磁化等离子体中低频动力学Alfven稀疏型孤波的特性.所得的结果表明,两种类型的动力学Alfven稀疏型孤波在磁层中大范围内均存在(参数β约为10-6-0.1,β为等离子体的热压与磁压之比,即β=2μ0 nT/B02),它们或以超Alfven速或以亚Alfven速传播.同时发现在β值较小(10-6-10-4)时,离子极化漂移非线性项对动力学Alfven孤波特性有较大的影响,不可忽略.而在较大值时(β～0.1),此修正作用不大.由于动力学Alfven孤波允许平行电场存在,故它对等离子体中带电粒子的加速和能化起重要作用;同时也对离子的横向加速有一定的作用,它使一种新的能量转换机制成为可能.

Considering the influence of ion's nonlinear polarization drift on Solitary Kinetic Alfven Wave (SKAW), the character of the low-frequency dip SKAW in the magnetic plasma is investigated with the two-fluid mode. The derived results indicate that two kinds of dip SKAW both exist in a wide range in magnetosphere (for the pressure parameter β - 10-6-0.1, where β is the ratio of thermal pressure to magnetic pressure, i.e. β = 2μ0 nT/B02). They propagate at Sub- Alfvenic speed or Super-Alfvenic speed. And ion's nonlinear polarization drift has great effect on the SKAW when the value of β is smaller (β-10-6-10-4). It can not be neglected. But it has weak effect on the SKAW when the value of β is bigger (β - 0.1). Because of the SKAW having the parallel electric field, the solitary wave is important for the acceleration and energy transmission of charged particles in magnetic plasma. And the SKAW is also put effects on the transverse ion transverse acceleration. The SKAW makes a novel kind of mechanism of energy transmission possible.