Extrapolator force field

From Tardis Wiki, the free Doctor Who reference

The extrapolator force field was created when the Ninth Doctor converted the tribophysical waveform macro-kinetic extrapolator into a force field to protect his TARDIS from the Dalek Fleet when they shot missiles. Captain Jack Harkness then linked it to the Game Station's defences to protect the top six floors with the field. (TV: The Parting of the Ways)