Friday, November 22, 2013

Nano-size superfluidity

Scientists at EPFL have provided the first experimental evidence of superfluidity at the nanoscale, shedding light on the fundamental basis of the phenomenon.

Superfluidity refers to a state in which matter behaves like a liquid with zero viscosity. Much like superconductivity, this phenomenon occurs at extremely low temperatures and can cause a liquid like helium to behave in the strangest ways, e.g. roll up out of a container or even create a perpetual fountain. But beyond just a fascinating curiosity, superfluidity is frequently used in high-precision applications like quantum gyroscopes and even satellites that measure infrared radiation in space. With a few exceptions, superfluidity has generally been regarded as a macroscopic phenomenon, resulting from ‘bulky’ collections of particles rather than individual atoms. But in a recent Physical Review Letters paper, EPFL researchers have now shown that, at least in liquids, superfluidity involves dynamics that go down to the nanoscale.

Thursday, November 21, 2013

Tips & Tricks - Vacuum Viewports

This had already been posted back in September 2007 on our old blog and as it had attracted tremendous interest I'm happy to give it a makeover with more detail !

For those who do not often change things on a UHV vacuum system, here's some tips if you need to mount a viewport. First, never use a viewport that appears to be, or is known to be damaged. A replacement viewport costs far less than repairing a system that has been subject of an implosion caused by a faulty viewport.

Pressure differentials: Kodial VPZ viewports are designed to withstand 1 Bar differential pressure. Other standard viewports are designed to withstand 2 Bar differential pressure. The pressure on the ‘vacuum side’ of the viewport must not exceed a positive pressure differential of 1 bar. The viewports are designed for vacuum applications.
  • WARNING: Pressures in excess of this or high reverse pressures may cause catastrophic failure and result in serious injury.

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