World Library  
Flag as Inappropriate
Email this Article

Plasma window

Article Id: WHEBN0001251318
Reproduction Date:

Title: Plasma window  
Author: World Heritage Encyclopedia
Language: English
Subject: StarTram, Mass driver, Exploratory engineering, 3D printing, List of plasma (physics) articles
Collection: Emerging Technologies, Plasma Physics
Publisher: World Heritage Encyclopedia

Plasma window

The plasma window (not to be confused with a plasma shield[1]) is a technology that fills a volume of space with plasma confined by a magnetic field. With current technology, this volume is quite small and the plasma is generated as a flat plane inside a cylindrical space.

Plasma is any gas that has had some of its atoms or molecules ionized and is generally held to be a separate phase of matter. This is most commonly achieved by heating the gas to extremely high temperatures, although other methods also exist. Plasma becomes increasingly viscous (thick) at higher temperatures, to the point where other matter has trouble passing through.

A plasma window's viscosity allows it to separate gas at standard atmospheric pressure from a total vacuum, in fact it is reported that it can withstand a pressure difference of up to nine atmospheres.[2] At the same time, the plasma window will allow radiation such as lasers and electron beams to pass. This property is the key to the plasma window's usefulness — the technology of the plasma window permits for radiation that can only be generated in a vacuum to be applied to objects in an atmosphere.[3][4] One of the major applications of this technology is electron beam welding, where it has made EBW practical outside of a hard vacuum.


  • History 1
  • Plasma valve 2
  • Properties 3
  • Similarity to "force fields" 4
  • See also 5
  • Other sources 6
  • Bibliography 7
  • References 8
  • External links 9


The Plasma Window was invented at Brookhaven National Laboratory[5] by Ady Hershcovitch and patented in 1995.[6]

Further inventions using this principle include the Plasma Valve in 1996.[7]

Plasma valve

A related technology is the plasma valve, invented shortly after the plasma window. A plasma valve is a layer of gas in the shell of a particle accelerator. The ring of a particle accelerator contains a vacuum, and ordinarily a breach of this vacuum is disastrous. If, however, an accelerator equipped with plasma valve technology breaches, the gas layer is ionized within a nanosecond, creating a seal that prevents the accelerator's recompression. This gives researchers time to shut off the particle beam in the accelerator and slowly recompress the accelerator ring to avoid damage.


The physical properties of the plasma window vary depending on application, but so far most have been generated at temperatures around 15,000 Kelvin (U.S. Patent 5,578,831)

The only limit to the size of the plasma window are current energy limitations as generating the window consumes around 20 kilowatts per inch (8 kW/cm) in the diameter of a round window.

The plasma window emits a bright glow, with the color being dependent on the gas used.

Similarity to "force fields"

In science fiction, such as the television series Star Trek, a fictional technology known as the "force field" is often used as a device. In some cases it is used as an external "door" to hangars on spacecraft, to prevent the ship's internal atmosphere from venting into outer space. Plasma windows could theoretically serve such a purpose if enough energy were available to produce them. The StarTram proposal plans on use of a power-demanding MHD window over a multi-meter diameter launch tube periodically, but briefly at a time, to prevent excessive loss of vacuum during the moments when a mechanical shutter temporarily opens in advance of a hypervelocity spacecraft.[8]

See also

Other sources

  • BNL Wins R&D 100 Award for `Plasma Window'[9]
  • Ady Hershcovitch. Plasma Window Technology for Propagating Particle Beams and Radiation from Vacuum to Atmosphere[10]


  • Ady Hershcovitch (1995). High-pressure arcs as vacuum-atmosphere interface and plasma lens for nonvacuum electron beam welding machines, electron beam melting, and nonvacuum ion material modification, Journal of Applied Physics, 78(9): 5283-5288


  1. ^
  2. ^
  3. ^
  4. ^
  5. ^
  6. ^
  7. ^
  8. ^
  9. ^
  10. ^

External links

  • Official article by Ady Hershcovitch - Inventor of the Plasma Window.
  • Brookhaven Lab Wins R&D 100 Award for the "Plasma Window"
  • Brookhaven National Laboratory - Where the Plasma Window was invented
  • News on the Plasma Window
  • Plasma Window Patent
  • Plasma Valve Patent
  • Diagram of plasma window in Ady Hershcovitch's electron beam welder (NewScientist)
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.