What is a Double Layer?
Electric double layers are like cliffs of potential (like a riverwaterfall) and can energise charged particles falling through them. They exist in the plasma environment of the earth and the stars and can cause phenomena as diverse as aurorae, luminous draperies in the polar sky, and electromagnetic radiation from rotating neutron stars called pulsars1. We have discovered such a double layer in our laboratory plasma systems and measured the energy of the highly supersonic ions it has accelerated. The fascinating part is that the double layer is not triggered by forcing two plasmas (independantly generated by grids with separate potentials, much like a man-made dam) to interact, but self generates under certain parameters, much like the riverbed suddenly falling away to create a waterfall. We are optimising this effect to create a very efficient thruster for interplanetary spacecraft.
1 M.A. Raadu, "The physics of double layers and their role in astrophysics", Physics reports 178, 25-97 (1989)
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