Cryogenics And The Future :: essays research papers

cryogenics and the Future     Cryogenics is a study that is of big importance to the human race andhas been a major project for engineers for the last 100 years. Cryogenics,which is derived from the Greek word kryos meaning "Icy Cold," is the study ofmatter at low temperatures. However low is not even the right word for thetemperatures involved in cryogenics, seeing as the highest temperature dealtwith in cryogenics is 100 (C (-148 (F) and the last(a) temperature used, is theunattainable temperature -273.15 (C (-459.67 (F). Also, when speaking ofcryogenics, the terms Celsius and Fahrenheit ar rarely used. Insteadscientists use a different measurement called the Kelvin (K). The Kelvin scalefor Cryogenics goes from 173 K to a fraction of a Kelvin above absolute zero.There are also two main sciences used in cryogenics, and they areSuperconductivity and Superfluidity.     Cryogenics first came about in 1877, when a Swiss Physicist name d RasulPictet and a French Engineer named Louis P. Cailletet liquefied oxygen for thefirst time. Cailletet created liquid oxygen in his lab using a process known asadiabatic expansion, which is a "thermodynamic process in which the temperatureof a gas is expanded without adding or extracting heat from the gas or thesurrounding system"(Vance 26). At the same time Pictet used the "Joule-ThompsonEffect," a thermodynamic process that states that the "temperature of a fluid is bring down in a process involving expansion below a certain temperature andpressure"(McClintock 4). After Cailletet and Pictet, a third method, known ascascading, was developed by Karol S. Olszewski and Zygmut von Wroblewski inPoland. At this point in history Oxygen was now able to be liquefied at 90 K,then soon afterwards liquid Nitrogen was obtained at 77 K, and because of theseadvancements scientist all over the world began competing in a race to lower thetemperature of matter to Absolut e Zero (0 K) Vance, 1-10.      because in 1898, James DeWar mad a major advance when he succeeded inliquifying hydrogen at 20 K. The reason this advance was so undischarged wasthat at 20 K hydrogen is also boiling, and this presented a very difficulthandling and shop problem. DeWar solved this problem by inventing a double-walled storage container known as the DeWar flask, which could contain and holdthe liquid hydrogen for a few days. However, at this time scientists realizedthat if they were going to make any to a greater extent advances they would have to have betterholding containers. So, scientists came up with insulation techniques that westill use today.