SPS & Beamed Energy Propulsion

>Problems I can identify:
>1. I don't know how efficient the solar sails are. So I don't know
>what the overall efficiency would be.
>2. Earth's magnetic field intensity decreases with altitude so I
>don't know how effective the tether is at GEO.
>3. Based on estimates from other papers on electrodynamic tethers
>and solar sails I have arrived at a back of the napkin performance
>calculation of 41 kg/kW. Not great but maybe workable.
>
>Can anybody point be to a resource that covers a similar concept?

I would like to point you to a solar sail concept which maybe could do
the lifting part for the tether.

http://solar-thruster-sailor.info/sts/sts.htm

The solar sail would have problems with the Earth atmosphere when
getting to cloth to its borders since wind forces are stronger than
the photons which power the solar sail.

You would need a pretty long tether. And I am not sure if the sail is
able to lift that big tether substantially even against atmospheric
border wind forces which may hit / decelerate the tether.

The design I propose would deliver for a 2260 m diameter round sail up
to 36 N constant thrust and could be able to produce about 480 mN of
steering force through the electric thrusters placed on its thruster
ring. See http://solar-thruster-sailor.info/sts/sts.htm#comparison
for said sail.
However the thrust degrades with the pointing angle of the sail.

Frank