晨昏起伏电场对中性片离子的随机加热

STOCHASTIC HEATING OF IONS IN THE NEUTRAL SHEET BY PERTURBED ELECTRIC FIELD

本文从哈密顿原理出发,讨论磁尾中性片中粒子受晨昏起伏电场的影响问题,并把它归结于讨论标准映射的性质.中性片本身是非线性系统,外加起伏场会导致其进入混沌状态.本文计算了进入该状态的临界电场E_c以及不同E下的粒子轨迹.计算表明,观测到的晨昏电场可以使离子进入混沌状态,但远小于电子的临界场值.这样离子运动是随机的,电子运动是规则的.仅对离子的随机加热可能是导致中性片中离子温度高于电子温度的原因.

In this paper the effects of the perturbed electric field on the motion of charged particles in the neutral sheet of the Earth's magnetotail are studied by the approaches of Hamilronian and standard mapping. Our calculations show that, under the action of the perturbed electric field, the ions may be chaotic near the separatrix in phase space, while the motion of the electron is regular. These results may be used to explain the observation that the temperature of ion is higher than that of electron in the neutral sheet of he Earth's magnetotail.