Dilution fridges (dil fridge for short) owe their cooling power to the incredible element helium and its two isotopes, helium-3 (3He) and helium-4 (4He). Though most people are familiar with it as the gas inside their party balloons (4He), helium can also condense into a liquid – but only at the very low temperature of 4.2 Kelvin (-269 degrees Celsius, or -452 degrees Fahrenheit). This property makes helium a very valuable cryogen in science. Using a condensation/evaporation cycle not unlike that of a kitchen refrigerator, a dil fridge takes 4.2 K liquid helium way down to 1.5 K.
The animation below illustrates how a dil fridge works. Use the play button to advance through the stages of operation.
Low Temperature Physics: The What, the How, the Why
Why do physicists want to study things at temperatures so cold atomic motion almost comes to a halt? And how do they create such frigid environments, anyway? Read on for the what, how and why of low temperature physics.
Cryogenics for English Majors
Fear not, right-brained friends: Science and art intersect in plenty of places, and this is one of them. Samuel Taylor Coleridge lends a hand as we explore cryogenics – how to get things fantastically frigid – and the fascinating element that makes it all possible.