Vakuum

Vakuum is the German term for vacuum, the physical condition in which a region of space contains little or no matter. In physics, a vacuum means gas pressures far below atmospheric; no real vacuum is perfectly empty, but chambers can reach extremely low particle densities and photon flux.

Pressure and scale: Vacuum is described by pressure, measured in pascals (Pa) or Torr. Rough or low vacuum reaches down to about 1 Torr; high vacuum spans roughly from 10^-3 to 10^-9 Torr; ultra-high vacuum is below 10^-9 Torr. As pressure decreases, mean free paths lengthen and residual gas densities drop, enabling cleaner environments for sensitive experiments and processes.

Generation and measurement: Vacua are produced with pumps such as rotary vane and scroll pumps for rough vacuum, turbomolecular, diffusion, and cryogenic pumps for higher vacua, and ion pumps for sustained ultrahigh vacuum. Vacuum is monitored with gauges including Pirani and thermocouple types for rough vacuum and ionization gauges for high to ultrahigh vacuum.

History and uses: The concept dates to the 17th century with Torricelli’s barometer and Guericke’s air-pump experiments, followed by improvements by Boyle, Cavendish, and others. Vacuum technology advanced to enable vacuum tubes, electron microscopy, semiconductor manufacturing, thin-film coating, degassing, and space-simulation experiments.

Note: The term Vakuum is also used in German-language literature to describe the quantum vacuum, the lowest-energy state of a quantum field. In everyday usage, the word primarily denotes environments with very low pressure.