Wireless Power Transfer Using an RF Plasma

Storing the energy from an RF plasma was once believed to be difficult. Here, we demonstrate how an RF plasma can be delivered through water or air and harvested as a storable DC voltage. In this method, experiments I and II were conducted to prove the feasibilities of transmitting a power as an RF plasma through water and air. In both experiments, the RF plasma was transmitted from an USB/ battery-powered RF plasma source with the help of a monopole antenna, whilst the power in the receiving end was captured using an Avramenko diode configuration and then multiplied using a multi-staged differential voltage multiplier. In both experiments, the results and efficiency of energy harvesting highly depended on the number of multiplication stages in the differential voltage multiplier. In experiment I, the RF power was successfully delivered along the surface of water as a surface wave to light up a neon lamp, with the measured transmission efficiency being stable over almost the whole transmission range. However, the transmission efficiency was weakly dependent upon the water conductivity. In experiment II, the RF power was successfully delivered through air but only over a rather limited transmission range, beyond which the approximate transmission efficiency was found to be inversely proportional to the transmission range. The Overall findings of this paper have opened up the possibility for 1) energizing wearable electronics with an RF plasma; 2) sensing of RF plasmas; and 3) harvesting electric energy of a natural plasma source such as a lightning strike over a wet land or an ocean.