Thermal Probe Enhanced with Pulsed Plasma Discharges for Efficient Ice Penetration

Abstract

Pulsed plasma discharges are investigated here as a means of reducing the power necessary for a thermal probe to penetrate an ice sheet. When a high-energy plasma discharge occurs in ice, the ensuing shockwave fractures the ice field and reduces its thermal conductivity. If this reduction is sufficient in both magnitude and geometric extension, it can decrease the heating power necessary to keep the thermal probe descending. This concept is investigated from a theoretical point of view by modeling in a finite element thermal analysis the effects of a cracked ice region on the thermal probe’s performance. Thermal conductivity reduction and cracked region extent are introduced as the parameters that predict power savings. An experimental setup was also created to allow 80 J discharges through an ice sample at a voltage of 40 kV. The system was used in combination with a commercial thermal properties analyzer to derive thermal conductivity reduction values to feed to the system. The cracked region was topologically divided into two regions with different cracking behavior, and the thermal conductivity of each region was measured.