Cluster observations and theoretical identification of broadband waves in the auroral region

Abstract

Abstract. Broadband waves are common on auroral field lines. We use two different methods to study the polarization of the waves at 10 to 180 Hz observed by the Cluster spacecraft at altitudes of about 4 Earth radii in the nightside auroral region. Observations of electric and magnetic wave fields, together with electron and ion data, are used as input to the methods. We find that much of the wave emissions are consistent with linear waves in homogeneous plasma. Observed waves with a large electric field perpendicular to the geomagnetic field are more common (electrostatic ion cyclotron waves), while ion acoustic waves with a large parallel electric field appear in smaller regions without suprathermal (tens of eV) plasma. The regions void of suprathermal plasma are interpreted as parallel potential drops of a few hundred volts.

Inhomogeneities of plasma density and electric field as sources of electrostatic turbulence in the auroral region

“…12) exhibits a similarity to the spectra of BBELF emissions. 12,30,31 We also note that the authors of the paper, 12 having tested several other modes to explain BBELF emissions, came to the conclusion that the IEDD waves are the most appropriate to interpret their observations.…”

“…3 Figure 12 exhibits a similarity to the BBELF spectra reported earlier (see, for example, Refs. 12,30,31). Therefore, the IEDD instability is a likely candidate to interpret in-situ observations of BBELF emissions.…”

General formulation for electrostatic solitons in multicomponent nonthermal plasmas

“…In their study the charge of each component is a free parameter while the charge neutrality for background plasmas is imposed. In light of the observational evidence for the existence of multiple components in space plasma environments [5][6][7][8][9], a number of theoretical models for electrostatic solitons in four-component plasmas have been developed [43][44][45][46]. In the present study we extend the formulations of Chuang and Hau [25,42] and Chuang [47] to more general cases with multiple (unlimited) hot components described by the combination of the kappa function and the more general nonthermal distribution function of…”

“…Plasmas consisting of multiple species of charged particles of different mass and electric charge, such as electron-positron-ion plasma or dusty plasma, may exist in many space and astrophysical environments as well as in the laboratory [1][2][3][4][5][6][7][8][9]. Due to the lack of collisions, in multispecies plasmas each component may possess different velocity distributions deviating from the thermal equilibrium.…”