Precision Differential Thermometers for Studying Thermal Processes at the Northern Caucasus Geophysical Observatory

Abstract

In order to study the fine structure of temperature fields in the rock strata, precision narrowband temperature sensors have been designed to measure temperature with an accuracy of at least 0.005°C. It is shown that the required sensitivity can be achieved by narrowing the measurement range and application of platinum thermoresistors and 24-bit ADCs for digital signal recording. The developed thermometer uses platinum thermoresistors, which have an almost linear temperature dependence of the change in internal resistance on the external temperature and an excellent long-term stability of their basic characteristics. To reduce the level of self-noise, special technical solutions (low-frequency filtering of both output signals and all supply voltages) are applied. The output differential signals of the thermometer enable its easy connection to a majority of modern digital data acquisition systems. The main methods for calibrating and setting the necessary operating temperature range of sensors are considered. Measurements with the developed sensors in the adit of the Northern Caucasus Geophysical Observatory, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, in the Baksan gorge will ensure unique data on the structure and dynamics of the thermal field near Elbrus volcano. Continuous monitoring is a particularly important task both for obtaining new fundamental knowledge about the structure of magmatic structures and assessing volcanic hazard from the presence of a fluid magmatic melt in the volcano’s interior. This, in turn, will provide new data on the potential hazard of Elbrus’ volcanic center . This research is especially important today in the light of the developing tourist infrastructure both in the Baksan gorge and in the entire Elbrus region.