Ground conductivity measurements with double tube Gerdien condenser

Abstract

The air molecules in the Earth's atmosphere can be ionized by cosmic rays solar high-energy radiation and radioactive materials These free charged particles are the source of the atmospheric electric conductivity The conductivity of the atmosphere varies with altitudes local times temperature humidity and aerosol concentration etc Nowadays many studies pointed out that the atmosphere conductivity may manifest a significant change before or after earthquakes The atmospheric vertical current density can be inferred by measuring the atmospheric conductivity and vertical electric field simultaneously and this parameter is essential for the charge circulation in the global electrical circuit model Therefore the measurement of atmospheric conductivity is very important In this study a double-tube Gerdien condenser is developed based on the design of the traditional Gerdien condenser as an atmospheric conductivity measurement instrument The instrument has new improvements to prevent the bias caused by the electrostatic lens Furthermore simultaneous measurement by two sets of coaxial tubes eliminates the voltage-switching surges After functional tests the double-tube Gerdien condenser is confirmed to be able to measure the atmospheric conductivity effectively Finally double-tube Gerdien condenser measured a long-term air conductivity trend in an outdoor environment It was found that the atmospheric conductivity is driven by several factors such as diurnal variation human activities and rainfall In addition a higher atmospheric conductivity was also identified when an earthquake occurred during this measurement

Date of Award	2021
Original language	English
Supervisor	Bing-Chih Chen (Supervisor)