Archives for October 2017

The development of particle accelerators was previously discussed (see Part 1 and 2 on Vacuum Technology at CERN). The use of the large hadron collider (LHC) located at CERN with its enormous, multiple vacuum systems is intended to investigate the fundamental particles of the universe and one of the most exciting in recent years being the search for the Higgs boson. Here we also take a closer look into the technologies used in the LHC, discussing some of the other discoveries it has led to, as well as reviewing past contributors to the field of vacuum technology whose innovations made the LHC possible.

The Standard Model of Particle Physics – Developed in its current form in the 1970’s, the so-called “Standard Model” of particle physics is a theory of fundamental particles and how they interact. It integrated all that was known about subatomic particles at the time and predicted the existence of additional particles as well. The Standard Model describes three of the four known fundamental forces in the universe – electromagnetic forces, weak nuclear, and strong nuclear interactions.

Vacuum furnaces can use a variety of different gases during the processing cycle in partial pressure operation, for backfilling to atmospheric pressure at the end of the processing cycle and for cooling/quenching. The most common of these gases (in order of frequency of use) are nitrogen, argon, hydrogen, and helium. Other common gases include various hydrocarbons and ammonia (for vacuum carburizing/carbonitriding) and specialty gases such as neon (for certain electronics applications).

In vacuum heat treatment nitrogen is used primarily for cooling/quenching, as a partial pressure gas and for backfilling to atmospheric pressure at the end of the heat treating cycle. A common misconception, however, is that nitrogen gas is a true inert gas. It is not and under the wrong circumstances, it can react with the surface of the material being heat treated with deleterious effects. Nitrogen has a gaseous specific gravity of 0.967 and as such is slightly lighter than air (whose specific gravity is 1.0) and has a boiling point of -195°C (–320.5°F) at atmospheric pressure. It is colorless, odorless and tasteless. Commercially, nitrogen is produced by a variety of air separation processes, including cryogenic liquefaction and distillation, adsorption separation and membrane separation (Special note: membrane separation technology typically does not produce a gas with high enough purity for vacuum use).