This launch ramp is supported by a 20km artificial mountain, largely constructed from graphene cells inflated with helium
Launch ramps use maglev tracks or similar powered accelerators to accelerate spaceraft to high speed before leaving the planet; this cuts down on the amount of fuel required to attain orbit. One design uses an evacuated tube, inclined from ground level to high elevation; the spacecraft is accelerated within the tube until reaching the upper atmosphere. Note that the tube must be actively evacuated or pressure inside and outside will equalise.
The ramp is often tens of kilometres high, with a relatively gentle slope, and mmay be many hundreds of kilometres long. The diamondoid support structure may be augmented by inflatable cells for support, often using helium cells. Alternately the ramp may be dynamically supported by space fountain technology.
A related concept is the Lofstrom Loop, a structure which requires much less mass as it is entirely self-levitating.
Lorrey Loop - Text by Steve Bowers Advanced form of Lofstrom Loop using three geostationary terminii in orbit at the points of an equilateral triangle, and three ground terminii opposite them, connected by a stream of vessels or particles which travel in Hofmann orbits (except when in the atmosphere), thereby saving energy.