Document DetailsAntifreeze-Thermal Electrical Drill (ATED)
|Authors:||Zagorodnov V, Kelley J, Stanford K, Koci B and Collins J|
|Periodical/Journal:||PICO Technical Note CP-92-03|
More than 10,000m of ice core have been taken in Arctic and Antarctic glaciers (1-5) by ATED. The deepest borehole in Central Antarctica (Komsomolskaya Station) drilled with ATED is 870 m in depth. The ice temperature is -53 degrees Celsius. Drilling was stopped at 800.6 m. After eleven months, drilling operations resumed. Investigation of the ice structure shows that fracture of the ice core due to thermal drilling by ATED and other thermal drills in cold and temperate glaciers also exist (6). At temperatures from 0 to -25 degrees Celsius, the mean penetration rate of an ATED was about 400m/week. As a test, the first 110m were drilled during a 24-hour period. The ethanol requirement was 10 to 50 percent of the borehole's volume.
The principle of operation of former ATEDs (Figure 1) is that the drill is immersed in an antifreeze solution (ethanol/water, glycols, salt water, etc.) in the borehole. The drill tip is fitted with a heating element that melts the ice. The melt water mixes with the antifreeze solution. The concentration of the antifreeze maintains the freezing point equal to the temperature of the surrounding ice. The primary specifications of the prototype antifreeze-thermal drill are given in Table 1.