Whistler waves generation and current closure by a pulsed tether in ionospheric plasmas

The dynamic response of ionospheric plasmas is modeled for current sources induced by a pulsed tether. A new method was developed which combines analytic and numerical techniques to study the dynamic response of a 2-D magnetoplasma to a time-dependent current source imposed across the magnetic field. The set of cold electron/ion plasma equations and Maxwellʹs equations are first solved analytically in (k,ω) space. Inverse Laplace and 2-D complex Fast Fourier Transform (FFT) techniques are subsequently used to numerically transform the radiation fields and plasma currents from (k,ω) space to (r,t) space. These results show that ionospheric plasmas respond to current sources induced by a pulsed tether through the excitation of whistler waves and formation of an expanding local current loop, induced by field-aligned plasma currents. The current loop consists of two antiparallel field-aligned current channels concentrated at the ends of the imposed tether current and a cross-field current region connecting these channels. The latter currents are driven by an electron Hall drift.