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Ion Acceleration Near CME-Driven Interplanetary Shocks

机译：CME驱动的行星际冲击附近的离子加速

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We have surveyed properties of the magnetic field power spectral densities and energetic ions and compared them with the shock normal angles of 74 CME-driven IP shocks observed at ACE and Wind during solar cycle 23. We searched for events that exhibited clear signatures of first-order Fermi acceleration at quasi-parallel shocks and shockdrift acceleration at quasi-perpendicular shocks as predicted by the diffusive shock acceleration theory. Our results show that events with clear signatures of either shock-drift or first-order Fermi acceleration at 1 AU are rare, with 64 of the 74 IP shocks (87%) exhibiting mixed signatures. We classify the remaining ten events as follows. (1) Type 1: Four quasi-perpendicular shocks with Bn > 70 exhibit no enhancements in the magnetic field power spectrum around the proton gyro-frequency and no change in the 80々300 keV/nucleon CNO spectral index upstream of the shocks, indicating the absence of upstream wave activity and the re-acceleration of a pre-existing suprathermal seed spectrum. (2) Six quasi-parallel or oblique IP shock events with Bn < 70 exhibit significant enhancements in the power spectral densities around the proton gyro-frequency and are accompanied by unfolding (softening) of the 80々300 keV/nucleon CNO spectral index upstream of the shocks, indicating the injection and acceleration of low-energy suprathermal seed particles that excite waves as they stream away from the shocks. Keywords: Energetic Particles, Interplanetary Shocks, Particle Acceleration.Abstract: We have surveyed properties of the magnetic field power spectral densities and energetic ions and compared them with the shock normal angles of 74 CME-driven IP shocks observed at ACE and Wind during solar cycle 23. We searched for events that exhibited clear signatures of first-order Fermi acceleration at quasi-parallel shocks and shockdrift acceleration at quasi-perpendicular shocks as predicted by the diffusive shock acceleration theory. Our results show that events with clear signatures of either shock-drift or first-order Fermi acceleration at 1 AU are rare, with 64 of the 74 IP shocks (87%) exhibiting mixed signatures. We classify the remaining ten events as follows. (1) Type 1: Four quasi-perpendicular shocks with Bn > 70 exhibit no enhancements in the magnetic field power spectrum around the proton gyro-frequency and no change in the 80々300 keV/nucleon CNO spectral index upstream of the shocks, indicating the absence of upstream wave activity and the re-acceleration of a pre-existing suprathermal seed spectrum. (2) Six quasi-parallel or oblique IP shock events with Bn < 70 exhibit significant enhancements in the power spectral densities around the proton gyro-frequency and are accompanied by unfolding (softening) of the 80々300 keV/nucleon CNO spectral index upstream of the shocks, indicating the injection and acceleration of low-energy suprathermal seed particles that excite waves as they stream away from the shocks.
机译：我们调查了磁场功率谱密度和高能离子的特性，并将它们与在太阳周期23期间在ACE和Wind处观察到的74个CME驱动的IP冲击的冲击法向角进行了比较。我们搜索了显示出以下特征的清晰事件：如扩散冲击加速度理论所预测的，准平行冲击的费米加速度和准垂直冲击的漂移加速度。我们的结果表明，在1 AU时具有电击漂移或一阶费米加速度的清晰特征的事件很少见，在74次IP冲击中有64个（87％）表现出混合特征。我们将其余十个事件分类如下。 （1）类型1：Bn> 70的四次准垂直电击在质子陀螺频率附近的磁场功率谱没有增强，并且震荡上游的80々300keV /核子CNO谱指数没有变化，表明不存在上游波活动和先前超热种子光谱的重新加速。 （2）Bn <70的六次准平行或倾斜IP冲击事件显示质子回旋频率附近的功率谱密度显着增强，并伴随着上游的80々300keV /核子CNO光谱指数的展开（软化）冲击，表明低能超热种子粒子的注入和加速，这些粒子在远离冲击波时激发波。关键词：高能粒子，行星际激波，粒子加速摘要：我们调查了磁场功率谱密度和高能离子的特性，并将其与74个CME驱动的IP激波在ACE和风中在太阳周期观察到的激波法线角进行了比较。 23.我们搜索了扩散振动加速度理论所预测的，在准平行冲击时表现出一阶费米加速度和在准垂直冲击时表现出明显漂移的明显特征的事件。我们的结果表明，在1 AU时具有电击漂移或一阶费米加速度的清晰特征的事件很少见，在74次IP冲击中有64个（87％）表现出混合特征。我们将其余十个事件分类如下。 （1）类型1：Bn> 70的四次准垂直电击在质子陀螺频率附近的磁场功率谱没有增强，并且震荡上游的80々300keV /核子CNO谱指数没有变化，表明不存在上游波活动和先前超热种子光谱的重新加速。 （2）Bn <70的六次准平行或倾斜IP冲击事件显示质子回旋频率附近的功率谱密度显着增强，并伴随着上游的80々300keV /核子CNO光谱指数的展开（软化）冲击，表明低能超热种子粒子的注入和加速，这些粒子在远离冲击波时激发波。

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