A review of electrodynamic tethers for science applications

Abstract

Abstract. A bare electrodynamic tether (EDT) is a conductive thin wire or tape tens of kilometres long, which is kept taut in space by gravity gradient or spinning, and is left bare of insulation to collect (and carry) current as a cylindrical Langmuir probe in an ambient magnetized plasma. An EDT is a probe in mesothermal flow at highly positive (or negative) bias, with a large or extremely large 2D sheath, which may show effects from the magnetic self-field of its current and have electrons adiabatically trapped in its ram front. Beyond technical applications ranging from propellantless propulsion to power generation in orbit, EDTs allow broad scientific uses such as generating electron beams and artificial auroras; exciting Alfven waves and whistlers; modifying the radiation belts; and exploring interplanetary space and the Jovian magnetosphere. Asymptotic analysis, numerical simulations, laboratory tests, and planned missions on EDTs are reviewed.

Tether radiation in Juno-type and circular-equatorial Jovian orbits

“…Ambient sulphur/oxygen ions impacting the tape both leave as neutrals and liberate additional secondary electrons, which are accelerated along magnetic field lines and could excite neutral molecules in the upper Jovian atmosphere, generating auroral emissions. Additionally, switching the contactor off would produce a large surge in both current and radiated power, setting up bias/current pulses along its length which are capable of emitting signals under a transmission line modeling [ Sanmartin , 2010]. It was recently suggested that current modulation in tethers might generate nonlinear, low frequency wave structures attached to the spacecraft.…”

Fast magnetosonic wave excitation by an array of wires with time-modulated currents

“…Following Vahala and Montgomery (1971), the dependent variables are written as made of three contributions of disparate magnitude, in a double independent linearization…”

“…The general formalism for a uniform pumped wave was first introduced by Nishikawa (1968). The parametric instability, has been predicted by Vahala and Montgomery (1971), before being observed in the laboratory (Lehane and Paoloni, 1972). The theoretical model was extended to include Hall and resistivity terms (Cramer, 1975) and boundary effects (Cramer and Sy, 1979).…”

“…Our analysis is focused on a region close to the tethered structure, where the radiated wave gives rise to a parametric instability usually known as magnetoacoustic pumping (Vahala and Montgomery, 1971). The general formalism for a uniform pumped wave was first introduced by Nishikawa (1968).…”

An Improved Electron Pre-Sheath Model for TSS-1R Current Enhancement Computations

“…Especially, spacecraft charging is a serious and practical concern in space engineering, and there have been extensive research activities aimed to address these issues. Among all approaches, tethering systems are quite effective to investigate the charging [3] and magnetic field effects [4], and there are some recent review papers in the literature [1,[5][6][7].…”