Thermal probe enhanced with pulsed plasma discharges for efficient ice penetration

Plasma drilling is a deep drilling technology which leverages electrical discharges to fracture rocks and sediments. In this work, plasma drilling is investigated as a performance enhancer for existing thermal-probe technology for use in planetary sub-glacial exploration missions. The hypothesis is that the cracking of ice induced by the spark discharges results in a local reduction of thermal conductivity capable of decreasing the conductive thermal losses that make up the majority of a thermal probe’s power budget in cryogenic ice conditions. Firstly, a simulation pipeline for melt probe performance is adapted to mimic the effects of plasma drilling on the ice surrounding a thermal probe. The simulation predicts the power necessary to keep a thermal probe moving at a certain descent velocity and can predict the expected energy savings as a function of thermal conductivity reduction and cracked region extent. Variation of ambient conditions, probe geometry and mission time are also investigated. Subsequently, the design iterations of a bench-top system used to store and distribute of energy 80J at 40kV are described. This system is at heart of the experimental portion of this work. The first application of the high-voltage setup is an experimental campaign tailored at finding the thermal conductivity reduction prompted by discharging in an ice sample. A commercially available thermal properties analyzer is used to collect thermal conductivity data. The efforts made to perform a direct comparison between a melt probe and plasma-enhanced thermal probe are also described. Accordingly, the design, construction and testing of a simple melt probe made out of commercial off the shelf components are presented. Subsequently, a high-voltage module capable of delivering pulsed-plasma discharges is designed and tested; this module can be integrated in the melt probe. In conclusion, the experimental setup intended to house the direct comparison between these two systems is also presented.