Wireless power transmission technology state of the art the first Bill Brown lecture

Abstract

This first Bill Brown SSP Technology Lecture covers the state-of-the-art (SOA) in wireless power transmission (WPT) technology including microwave and laser systems for the transfer of CW electric power, as related to eventually developing Space Solar Power (SSP) systems. Current and past technology accomplishments in ground based and air and space applied energy conversion devices, systems and modeling information is presented, where such data are known to the author. The purpose of the presentation is to discuss and present data to encourage documenting and breaking the current records, so as to advance the SOA in WPT for SSP. For example, regarding DC to RF and laser converters, 83% efficient 2.45 GHz cooker-tube magnetrons with 800 W CW output have been developed by CPII and the Russians. Over 50% wall-plug efficient 1.5 kW/cm 2 CW, water-cooled, multibeam, solid state laser diode bar-arrays have been developed by LLNL at 808 nm wavelength. The Germans have developed a 36% efficient, kW level, single coherent beam, lateral pumped semiconductor laser. The record for end-to-end DC input to DC output power overall WPT link conversion efficiency is 54% achieved during the Raytheon-JPL experiments in 1975 for 495.6 W recovered at 1.7 −m range, at 2.4469 GHz The record for usefully recovered electric power output (as contrasted with thermally induced power in structures) is 34 kW DC output at a range of 1.55 km, using 2.388 GHz microwaves, during the JPL-Raytheon experiments by Bill Brown and the author at Goldstone, CA in 1975. The GaAs-diode rectenna array had an average collection-conversion efficiency of 82.5%. A single rectenna element developed by Bill Brown demonstrated 91.4% efficiency. The comparable record for laser light to DC output power conversion efficiency of photovoltaics is 59%, for AlGaAs at 1.7 W and 826-nm wavelength.