Approach to Absolute Zero

Abstract

Termodinamika niskih temperatura odnosi se na primjenu zakona termodinamike na osobine materije na temperaturama oko apsolutne nule. Za proučavanje tih osobina potrebno je razmotriti procese hlađenja koji nam omogućuju postizanje takvih temperatura. Njih općenito možemo definirati kao procese prijenosa topline s mjesta niže na mjesto više temperature. Cilj ovog završnog rada je dati teoretski opis tehnika hlađenja koje su danas najzastupljenije u postizanju ultraniskih temperatura. Tehnike hlađenja se pri tome vrednuju prema njihovim snagama hlađenja koje opisuju efikasnost hlađenja određenog sustava, ali isto tako postavljaju granice mogućnosti koje su određene drugim i trećim zakonom termodinamike.Low temperature thermodynamics represents a field of study for characteristics of materials at temperatures close to absolute zero. For studying such characteristics one must consider the cooling techniques which allow us to reach such temperatures. Cooling can generaly be defined as heat transfer from a body at lower to a body at higher temperatures. The aim of this final paper is to give a theoretical description of todays most abundantly used refrigeration techniques for reaching very low temperatures. These techniques are quantified according to their cooling power, which describes the cooling efficiency of a given system, but at the same time sets the limit of possibility for reaching low temperatures according to the second and third law of thermodynamics