| 行星际磁场脉动能谱随日心距离变化的模式 |
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| 引用本文： | 涂传诒.行星际磁场脉动能谱随日心距离变化的模式[J].地球物理学报,1983,26(5):405-416. |
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| 作者姓名： | 涂传诒 |
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| 作者单位： | 北京大学地球物理系 |
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| 摘 要： | 空间飞船Helios 1和Helios 2的磁场探测发现,太阳风高速流中磁场脉动在低频区的能谱的谱指数是随日心距离r而变化的,谱密度的空间梯度是随频率f而变化的,现有关于行星际磁场脉动的理论都不能解释上述现象。本文提出了一个计算行星际磁场能谱径向发展的理论模式。假设在不同频率的脉动之间有由低频向高频传输的能流存在,在这一基础上建立了谱方程,并得到了谱方程的数值解。数值解表明,由0.3AU至1AU,低频区的谱指数增加,而高频区的谱指数近似保持为常数（-1.6）;低频区平均谱密度随着日心距离的变化为r-3.5,在高频区为r-4.1,所有这些都与观测相符合。串级的能量很可能最后传输到质子回旋频率范围,由于回旋共振而耗散,最后加热太阳风质子。这一模式有可能用来计算太阳风的加速问题。
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| 关 键 词： | 日心距离 行星际磁场 脉动能 径向变化 波模 能谱 谱方程 太阳风 谱密度 外传播 |
| 收稿时间： | 1982-08-26 |
A MODEL FOR THE RADIAL VARIATION OF THE POWER SPECTRA OF THE IMF FLUCTUATIONS |
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| TU CHUAN-YI.A MODEL FOR THE RADIAL VARIATION OF THE POWER SPECTRA OF THE IMF FLUCTUATIONS[J].Chinese Journal of Geophysics,1983,26(5):405-416. |
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| Authors: | TU CHUAN-YI |
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| Institution: | Department of Geophysics, Pelting University |
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| Abstract: | A model for the radial variation of the power spectrum of the IMP fluctuations is presented in this paper. The basic idea is that the fluctuations in the frequency range round 10-4Hz propagating from the sun to the earth's orbit are nearly as predicted by the WKB Alfvén waves model, but a small part of energy cascades into the frequency range above 10-3 Hz, in which the fluctuations are controlled by the cascading process-Based on this idea, a power spectrum equation of the IMP fluctuations including a cascading term is presented and numerical solutions of the spectrum equation are given. The solutions show that the slope of the spectrum in the frequency range higher than 10-2 Hz nearly remains -1.6 while the slope of the spectrum in the low frequency range around 10-3 Hz increases from 0.3 AU to 1 AU. The average spectrum density over the frequency range 2.8×10-4Hz- 2.5×10-3 Hz varies with distance as r-3.5 while that over 1.0 × 10-2 Hz-8.3×10-2 Hz as r-4.1 in the space 0.3 AU to 1 AU. All of the properties calculated are consistent with the radial evolution of the power spectrum of IMP fluctuations first observed by Helios 1 and Helios 2 （Bavassano, 1982）. The numerical solution shows that the energy flux of the fluctuations near the sun is of the order of 104 erg cm-2s-1, that is, the same as the wave energy flux some solar wind theories seem to require. |
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