I was just watching some of the theory behind the LHC and it got me thinking. Financial costs aside what is stopping the development of something like this in space. A large ring in which a space craft enters and where its velocity is increased using magnetic fields. The spacecraft continues its journey around the ring continually until a specified velocity is reached when it is then propelled on the desired trajectory. Energy requirements would be lower as space provides lower temperatures which makes superconducting easier. Obviously it would not reach the speed of light (e= mc^2) but theoretically it could be accelerated to speeds significantly higher than standard rocket fuel propelled craft. Obviously this is an over simplistic view but I don't understand why the underlying principal couldn't be used. Hmmm better get back to some uni assignments.