The idea behind
using an EDT as a generator is having the
tether intersect the earths magnetic field.
This in return results in a conductivity of
the wire; then the wire transforms some of the
kinetic energy to electrical energy in which
the spacecraft can use aboard the spacecraft.
A better way to describe this is "When the
tether intersects the planet's magnetic field,
it generates a current, and thereby converts
some of the orbiting body's kinetic energy to
electrical energy. Functionally, electrons
flow from the space plasma into the conductive
tether, are passed through a resistive load in
a control unit and are emitted into the space
plasma by an electron emitter as free
electrons. As a result of this process an
electrodynamic force acts on the tether and
attached object, slowing their orbital motion.
In a loose sense, the process can be likened
to a conventional windmill- the drag force of
a resistive medium(air or, in this case, the
magnetosphere) is used to convert the kinetic
energy of relative motion(wind, or the
satellite's momentum) into electricity. In
principle, compact high-current tether power
generators are possible, and with basic
hardware, tens, hundreds, and thousands of
kilowatts appears to be
attainable."(Wikipedia)
Below is an equation that describes the
voltage across a conductor
Image from: "STS-75 Tethered Satellite System
deployment" by NASA Johnson Space Center
(NASA-JSC), Image-ID: sts075-701-087 -
http://nix.ksc.nasa.gov/info?id=sts075-701-087&orgid=8.
Licensed under Public Domain via Wikimedia
Commons -
http://commons.wikimedia.org/wiki/File:STS-75_Tethered_Satellite_System_deployment.jpg#/media/File:STS-75_Tethered_Satellite_System_deployment.jpg
