Homeland Security Daily Wire has the inside take on new propulsion technology that could potentially fuel the next generation of surveillance machines:

Here is a question from High School science class: Pass a current or magnetic field through a conducting fluid — and what will happen? Answer: it will generate a force. Numerous aerospace engineers have tried and failed to exploit this phenomenon, known as magnetohydrodynamics, as an exotic form of propulsion for aircraft, but perhaps these attempts, so far, have all been too big.

A very small design could have a better chance of taking off, says Subrata Roy, an aerospace engineer at the University of Florida in Gainesville. With a span of less than fifteen centimetres, his aircraft qualifies as a micro air vehicle (MAV), but it has an unconventional design: it is a saucer shape covered with electrodes which ionize air to create a plasma. This plasma is then accelerated by an electric field to push air around and generate lift.

Roy says the machine can be filled with helium to reduce its weight, and is efficient enough to be powered by on-board batteries. Its ability to hover and generate lift electronically means that it is particularly robust against gusts of wind which send other MAVs off course, says Roy. All he needs to do now is build one and get it flying. As is the case with other MAVs, the primary application would probably be surveillance, but a plasma flying saucer would make a great toy too.