Computer controlled data acquisition system for the NASA 1986 Rocket Triggered Lightning Program

The lightning-strike object (LSO) for the NASA 1986 Rocket Triggered Lightning Program (RTLP-86) was provided jointly by Sandia National Laboratories and Lawrence Livermore National Laboratory. The LSO was a large Faraday-cage-like metal canister containing electronic equipment with an electrical cable extending to a lightning rod 7 m above the canister. The lightning attachment was to the cable outer shield, which was shorted to the inner conductor(s) at the top end of the cable. Transient limiters were employed on each conductor entering the canister. Measurements were made both inside and outside. Computer controlled digital oscilloscopes were chosen to handle the large amount of data and for a fast system response. Eight dual-channel oscilloscopes, a computer, printer, and plotter recorded lightning stroke current applied to the LSO and various voltage and current responses inside. Computer software was written specifically for the RTLP-86 to collect and store data from the oscilloscopes. Turn-around time for the instrumentation system was two to three minutes. Isolation from lightning-induced currents and EMI was maintained through the use of nine fiber-optic data links between the sensors and the recording equipment which was housed in a metal building (actually a railroad caboose). Control and recording power was from amore » diesel generator located beside the caboose. Data was recorded from 22 lightning flashes containing more than 80 return strokes. The maximum peak stroke current was 52 kA. Typical data is presented. 8 refs., 13 figs., 1 tab.« less