Abstract

The dynamics of fluxes of thermal and suprathermal H⁺ and O⁺ ions and the pressure variations of these components during 11 events of magnetic field dipolarization in the plasma sheet of the geomagnetic tail are analyzed based on Cluster satellite observations. It was found that the energy of H⁺ and O⁺ ions corresponding to the maximum flux approached or exceeded the upper energy threshold of CODIF thermal plasma mass spectrometers (~40 keV) in all of the events. During such periods, the determined values of the density, temperature, and pressure in an energy range up to 40 keV are underestimated as compared to the actual values. To determine the pressure during such intervals, we used measurements of the ion-component fluxes in an energy range up to 1.3 MeV based on a joint analysis of observations of CODIF and RAPID energy-mass spectrometers. As a result, it was found that the ion pressure during dipolarization with the high-energy component of the spectrum taken into account can be several times higher than the pressure determined in the range up to 40 keV. Using the superposed epoch analysis, we showed that the error associated with underestimation of the pressure of the H⁺ and O⁺ ion components is largest during the dipolarization growth phase. The underestimation is most significant for the O⁺ ion pressure.

中文翻译：

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近地磁尾等离子体板双极化过程中离子组分压力的变化

摘要

基于簇状卫星观测资料，分析了11个地磁尾等离子体中的磁场偶极化过程中H ⁺和O ⁺和H ⁺和H ⁺离子的通量动态和这些成分的压力变化。发现H ⁺和O ⁺的能量在所有情况下，对应于最大通量的离子都接近或超过了CODIF热等离子体质谱仪的能量上限（〜40 keV）。在此期间，与实际值相比，在最高40 keV的能量范围内确定的密度，温度和压力值被低估了。为了确定这样的时间间隔内的压力，我们基于对CODIF和RAPID能量质谱仪的观测结果的联合分析，使用了能量范围高达1.3 MeV的离子组分通量的测量值。结果发现，考虑到光谱的高能量分量，在双极化期间的离子压力可以比在高达40keV的范围内确定的压力高几倍。使用叠加时代分析，在双极化生长阶段，⁺和O ⁺离子成分最大。对于O ⁺离子压力，低估最为明显。