Observations of Small Large-Amplitude Magnetic Structures (SLAMS) at
Mars by MAVEN
Abstract
According to the different orientations of the interplanetary magnetic
field (IMF), the planetary shock can be either quasi-parallel or
quasi-perpendicular. Under quasi-parallel conditions a significant
number of solar wind suprathermal particles are reflected from the shock
and drift along IMF, forming an extended and highly turbulent region
called the foreshock where various nonlinear plasma phenomena are
observed. In this research, we perform a case study of the structures in
the foreshock region at Mars observed by Mars Atmosphere and Volatile
Evolution (MAVEN). We use data from plasma analyzer STATIC and
magnetometer MAG to analyze ion beams angular spectrum and magnetic
field dynamics. We show that the observed structures are consistent with
Short Large-Amplitude Magnetic Structures (SLAMS), commonly detected in
foreshock regions of magnetized and unmagnetized bodies throughout the
Solar system. Finally, we calculate the magnetic Mach number to analyze
the characteristics of the observed foreshock structures. The analysis
shows, that SLAMS are formed by the resonance between plasma waves
propagating along the IMF and the backstreaming scattered solar wind H+
and exospheric O+ and O2+ ions, with the dominant impact of O2+ ions.