Abstract:
Vector measurements of middle atmospheric electric fields are mostly carried out using a double-Langmuir
probe technique on platforms like balloons and rockets. High impedances (up to 1013 ohms) and low signal
levels (~few millivolts) are the factors that are to be considered in the design of an electrometer for one such
experiment. Here, we offer a simple circuit concept that invokes an instrumentation amplifier capable of
meeting our several needs, namely generating the guard voltage, ultra-high impedance (1015 ohms) input
terminals, femtoampere bias current, differencing, gain setting, etc. all in one package. A three-channel
differential electrometer was developed based on this concept and flown on a high-altitude balloon platform.
Results reveal that the instrument is capable of detecting weak electric field variations at stratospheric
altitudes.
