Space shield to block radiation

British scientists are planning to see whether a Star Trek-style deflector shield could be built to protect astronauts from radiation.

--news.bbc.co.uk...

The goal of this technology is to surround a ship with an electromagnetic field that would propel unfriendly radiation away. How great is that?

I've heard of this concept before. Robert Zubrin suggested that a magnetic sail could be used for a mars mission as it would be more efficient than a solar sail and provide a shield against solar radiation. The VASIMIR concept would also have the added benefit of a electro-magnetic shield as a result of the plasma expelled for propulsion.