Bin Miao | University of Science and Technology of China (original) (raw)

Papers by Bin Miao

Research paper thumbnail of Ion thermalization and wave excitation downstream of Earth's bow shock: A theory for Cluster observations of He 2+ acceleration

Journal of Geophysical Research, 2007

1] It has been well documented that the plasma immediately downstream of Earth's quasi-perpendicu... more 1] It has been well documented that the plasma immediately downstream of Earth's quasi-perpendicular bow shock, which consists of reflected protons and directly transmitted ions with large temperature anisotropies (T ? /T z ), is unstable to the excitation of ion cyclotron waves. These waves in turn scatter the protons and ions to marginal stability. Using Cluster data following the inbound shock crossing at 1717:48 UT on 31 March 2001, we investigate the joint evolution of the proton and helium distribution functions. Within a short distance downstream of the shock the perpendicular heating of helium is faster than the parallel heating, so that the temperature anisotropy of helium first increases near the shock before decreasing farther downstream. The observed spectra of magnetic fluctuations, which are dominated by left-hand circularly polarized waves, display one peak atṽ <ṽ ga (He 2+ gyrofrequency), just downstream of the shock, and two peaks with a slot nearṽ %ṽ ga , farther downstream, whereṽ is wave frequency in hertz. We present a quasi-linear theory that accounts for the observed long-time decrease of the He 2+ temperature anisotropy and the excited wave spectrum. The predicted temperature anisotropy and the general shape of the excited wave spectrum match the observations remarkably well. Nevertheless, certain features of the observations, such as the large amplitude of the lower-frequency peak and very low amplitude of the higherfrequency peak just downstream of the shock, require further work. Citation: Liu, Y. C.-M., M. A. Lee, H. Kucharek, and B. Miao (2007), Ion thermalization and wave excitation downstream of Earth's bow shock: A theory for Cluster observations of He 2+ acceleration,

Research paper thumbnail of Remote sensing of local structure of the quasi-perpendicular Earth's bow shock by using field-aligned beams

Annales Geophysicae, 2009

Field-aligned ion beams (FABs) originate at the quasi-perpendicular Earth's bow shock and constit... more Field-aligned ion beams (FABs) originate at the quasi-perpendicular Earth's bow shock and constitute an important ion population in the foreshock region. The bulk velocity of these FABs depends significantly on the shock normal angle, which is the angle between shock normal and upstream interplanetary magnetic field (IMF). This dependency may therefore be taken as an indicator of the local structure of the shock. Applying the direct reflection model to Cluster measurements, we have developed a method that uses proton FABs in the foreshock region for remote sensing of the local shock structure. The comparison of the model results with the multi-spacecraft observations of FAB events shows very good agreement in terms of wave amplitude and frequency of surface waves at the shock front.

Research paper thumbnail of On the physics of collisionless shocks: Cluster investigations and simulations

Journal of Atmospheric and Solar-terrestrial Physics, 2008

Collisionless shocks can be found in many astrophysical settings but the Earth's environment... more Collisionless shocks can be found in many astrophysical settings but the Earth's environment is easiest to access. The foreshock region of the Earth's bow shock is populated by a variety of waves and particle populations allowing us to study wave–particle interactions. In the parallel and quasi-parallel regime short large amplitude magnetic structures (SLAMS) and their properties have been investigated. At

Research paper thumbnail of Ion thermalization and wave excitation downstream of Earth's bow shock: A theory for Cluster observations of He 2+ acceleration

Journal of Geophysical Research, 2007

1] It has been well documented that the plasma immediately downstream of Earth's quasi-perpendicu... more 1] It has been well documented that the plasma immediately downstream of Earth's quasi-perpendicular bow shock, which consists of reflected protons and directly transmitted ions with large temperature anisotropies (T ? /T z ), is unstable to the excitation of ion cyclotron waves. These waves in turn scatter the protons and ions to marginal stability. Using Cluster data following the inbound shock crossing at 1717:48 UT on 31 March 2001, we investigate the joint evolution of the proton and helium distribution functions. Within a short distance downstream of the shock the perpendicular heating of helium is faster than the parallel heating, so that the temperature anisotropy of helium first increases near the shock before decreasing farther downstream. The observed spectra of magnetic fluctuations, which are dominated by left-hand circularly polarized waves, display one peak atṽ <ṽ ga (He 2+ gyrofrequency), just downstream of the shock, and two peaks with a slot nearṽ %ṽ ga , farther downstream, whereṽ is wave frequency in hertz. We present a quasi-linear theory that accounts for the observed long-time decrease of the He 2+ temperature anisotropy and the excited wave spectrum. The predicted temperature anisotropy and the general shape of the excited wave spectrum match the observations remarkably well. Nevertheless, certain features of the observations, such as the large amplitude of the lower-frequency peak and very low amplitude of the higherfrequency peak just downstream of the shock, require further work. Citation: Liu, Y. C.-M., M. A. Lee, H. Kucharek, and B. Miao (2007), Ion thermalization and wave excitation downstream of Earth's bow shock: A theory for Cluster observations of He 2+ acceleration,

Research paper thumbnail of Remote sensing of local structure of the quasi-perpendicular Earth's bow shock by using field-aligned beams

Annales Geophysicae, 2009

Field-aligned ion beams (FABs) originate at the quasi-perpendicular Earth's bow shock and constit... more Field-aligned ion beams (FABs) originate at the quasi-perpendicular Earth's bow shock and constitute an important ion population in the foreshock region. The bulk velocity of these FABs depends significantly on the shock normal angle, which is the angle between shock normal and upstream interplanetary magnetic field (IMF). This dependency may therefore be taken as an indicator of the local structure of the shock. Applying the direct reflection model to Cluster measurements, we have developed a method that uses proton FABs in the foreshock region for remote sensing of the local shock structure. The comparison of the model results with the multi-spacecraft observations of FAB events shows very good agreement in terms of wave amplitude and frequency of surface waves at the shock front.

Research paper thumbnail of On the physics of collisionless shocks: Cluster investigations and simulations

Journal of Atmospheric and Solar-terrestrial Physics, 2008

Collisionless shocks can be found in many astrophysical settings but the Earth's environment... more Collisionless shocks can be found in many astrophysical settings but the Earth's environment is easiest to access. The foreshock region of the Earth's bow shock is populated by a variety of waves and particle populations allowing us to study wave–particle interactions. In the parallel and quasi-parallel regime short large amplitude magnetic structures (SLAMS) and their properties have been investigated. At