Generation of field-aligned currents by VLF waves in the magnetosphere

Abstract

This paper shows that VLF waves can be a source for the high energy electrons of tens of keV, carrying the small scale magnetic field-aligned Birkeland currents of sizes < 50 km in the magnetosphere. The dispersion relation for whistler mode waves in a magnetized plasma consisting of cold, warm and hot electrons and a beam of electrons carrying the current is examined. The VLF growth rates in the presence of field-aligned currents are found to be weaker and the current carrying electrons extract energy from the VLF waves. Along with the dependence of field-aligned currents and VLF waves on the magnetic activity, both these parameters also depend on each other directly.