What plausible reason could I give for my FTL drive only working in space

I've created a fairly fleshed out, detailed FTL concept. Basically, you have a circular starship, with a ring of tungsten encircling that, held in place by an antigravity ring beneath it. The rim of the starship consists of a plasma window - basically superheated plasma held in place by a magnetic field. This plasma is made from a material that, when, strongly heated, emits radiation. This radiation converts ordinary matter into Negative Matter (so, matter with a negative mass). Once enough of the tungsten ring has converted into Negative Matter (and the amount needed is pretty small) an Alcubierre-style warp bubble is created around the ship, taking it to its destination at a speed faster than light. For story reasons, I'd like it to be the case that these ships can only work in space - so a ship has to first leave the atmosphere of whatever planet or body it is on before it can fire its warp drive. Considering its mode of operation, is there any plausible reason why this could be?

posted over 5 years ago

Locaq‭

1 reputation 5 0 0 0