L. Brad King’s prototype of a ferrofluid ion thruster. When subjected to magnetic field, the points of the crown arise from a ring-shaped trench circling a one-inch block of aluminum. (Credit: Sarah Bird)
then an electric field is applied which makes the ‘points’ extend to nano scale and then emit ionic molecules at high velocity. Very neat, self forming, self healing, some scaling details to work out but this looks very promising. Another tech breakthrough from Air Force R&D.