LIMIT ON STABLY TRAPPED PARTICLE FLUXES
LIMIT ON STABLY TRAPPED PARTICLE FLUXES
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DOI：
10.1029/jz071i001p00001
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发表时间：
1966-01-01
影响因子：
--
通讯作者：
PETSCHEK, HE
中科院分区：
文献类型：
--
作者：
KENNEL, CF;PETSCHEK, HE
惠斯勒模式噪声会导致电子的俯仰角扩散。类似地，离子回旋噪声与离子耦合。这种扩散导致粒子沉淀到电离层，并产生不稳定的捕获粒子的俯仰角分布，不利于进一步的波增长。由于波的过度增长会导致快速扩散和粒子损失，因此将增长速率限制为波传播耗尽波能的速率的要求允许对捕获的赤道粒子通量的上限进行估计。在探测器14和12上分别观测到的40keV的电子通量和120keV的质子通量都符合这一极限，偶尔也有例外。BeyondL=4时，通量略低于它们的极限，这表明存在一个未指明的加速源，足以将被捕获的粒子保持在它们的降水极限附近。极限质子通量和电子通量大致相等，这部分解释了高能质子密度大于电子密度的原因。观察到的电子节距角分布对应于与观察到的寿命一致的扩散系数。所需的赤道哨声模宽带噪声强度为10−2γ，与观测没有明显的不一致，与寿命和极限俘获粒子强度一致。
Whistler mode noise leads to electron pitch angle diffusion. Similarly, ion cyclotron noise couples to ions. This diffusion results in particle precipitation into the ionosphere and creates a pitch angle distributon of trapped particles that is unstable to further wave growth. Since excessive wave growth leads to rapid diffusion and particle loss, the requirement that the growth rate be limited to the rate at which wave energy is depleted by wave propagation permits an estimate of an upper limit to the trapped equatorial particle flux. Electron fluxes >40 kev and proton fluxes >120 kev observed on Explorers 14 and 12, respectively, obey this limit with occasional exceptions. BeyondL= 4, the fluxes are just below their limit, indicating that an unspecified acceleration source, sufficient to keep the trapped particles near their precipitation limit, exists. Limiting proton and electron fluxes are roughly equal, suggesting a partial explanation for the existence of larger densities of high‐energy protons than of electrons. Observed electron pitch angle profiles correspond to a diffusion coefficient in agreement with observed lifetimes. The required equatorial whistler mode wide band noise intensity, 10−2γ, is not obviously inconsistent with observations and is consistent with the lifetime and with limiting trapped particle intensity.