Editing Plasma window

{{Short description|Force field based on high-energy plasma}}
The '''plasma window''' (not to be confused with a ''plasma shield''<ref>{{cite news| last = Shiga| first =David| title =Plasma bubble could protect astronauts on Mars trip| publisher =[[New Scientist]]| date =2006-07-17| url =https://www.newscientist.com/article/dn9567-plasma-bubble-could-protect-astronauts-on-mars-trip.html| accessdate = 2008-04-02}}</ref>) is a technology that fills a volume of space with [[plasma (physics)|plasma]] confined by a [[magnetic field]]. With current [[technology]], this [[volume]] is quite small and the plasma is generated as a flat [[plane (mathematics)|plane]] inside a [[cylinder (geometry)|cylindrical]] space.

Plasma is any [[gas]] whose [[atom]]s or [[molecule]]s have been [[ionization|ionized]], and is a separate [[phase (matter)|phase]] of matter. This is most commonly achieved by heating the gas to extremely high temperatures, although other methods exist. Plasma becomes increasingly [[viscosity|viscous]] at higher temperatures, to the point where other matter has trouble passing through.

A plasma window's viscosity allows it to separate gas at [[atmospheric pressure#Standard atmosphere|standard atmospheric pressure]] from a total [[vacuum]], and can reportedly withstand a pressure difference of up to nine [[atmosphere (unit)|atmospheres]].<ref>{{cite web|url=https://www.newscientist.com/article/mg17823904.800-hot-mettle.html?full=true |title=Hot mettle |publisher=Newscientist.com |accessdate=2015-05-04}}</ref> At the same time, the plasma window will allow [[radiation]] such as [[laser]] beams and [[charged particle beam|electron beam]]s to pass. This property is the key to the plasma window's usefulness – the technology of the plasma window allows radiation that can only be generated in a vacuum to be applied to objects in an atmosphere.<ref>{{cite news| title = Plasma Window Technology for Propagating Particle Beams and Radiation from Vacuum to Atmosphere| publisher = Nasa Tech Briefs| date =1998-05-01| url =http://www.techbriefs.com/content/view/1834/32/| accessdate = 2008-04-02}}</ref><ref>{{cite news| last = Kaku| first = Michio| title = Physics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel| publisher =[[The Wall Street Journal]]| date =2008-03-14| url =https://www.wsj.com/articles/SB120534908289431017?mod=googlenews_wsj| accessdate = 2008-04-02}}</ref> [[Electron-beam welding]] is a major application of plasma windows, making it practical outside a hard vacuum.

== History ==
The plasma window was invented at [[Brookhaven National Laboratory]]<ref>{{cite news| title =Hot mettle| publisher =[[New Scientist]]| date =2003-04-12| url =https://www.newscientist.com/article/mg17823904.800-hot-mettle.html| accessdate = 2008-04-02}}</ref> by [[Ady Hershcovitch]] and patented in 1995.<ref name=pw_patent>{{cite web|url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5578831.PN.&OS=PN/5578831&RS=PN/5578831|title= United States Patent: 5578831:Hershcovitch (November 26, 1996) Method and apparatus for charged particle propagation|publisher=Patft.uspto.gov|accessdate=2016-03-01}}</ref>

Further inventions using this principle include the plasma valve in 1996.<ref>{{cite web|url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6528948.PN.&OS=PN/6528948&RS=PN/6528948|title= United States Patent: 6528948:Hershcovitch (March 4, 2003) Plasma valve|publisher=Patft.uspto.gov|accessdate=2016-03-01}}</ref>

In 2014, a group of students from the [[University of Leicester]] released a study describing functioning of spaceship plasma deflector shields.<ref name="urlStudents prove real-life Star Wars deflector shield is possible - ExtremeTech">{{cite web |url=https://www.extremetech.com/extreme/181773-physics-students-figure-out-how-to-make-star-wars-deflector-shields-in-real-life |title=Students prove real-life Star Wars deflector shield is possible - ExtremeTech |format= |accessdate=}}</ref>

In 2015, [[Boeing]] was granted a [[patent]] on a force field system designed to protect against [[shock wave]]s generated by explosions. It is not intended to protect against projectiles, radiation, or energy weapons such as lasers. The field purportedly works by  using a combination of lasers, electricity and microwaves to rapidly heat up the air creating a field of (ionised) superheated air-plasma which disrupts, or at least attenuates, the shock wave. As of March 2016, no working models are known to have been demonstrated.<ref>{{cite web |url=http://abcnews.go.com/Technology/boeing-patents-star-wars-style-force-field-technology/story?id=29839654 |title=Boeing Patents 'Star Wars'-Style Force Field Technology |author=Alyssa Newcomb |date=March 23, 2015 |publisher=ABC News |accessdate=March 23, 2015}}</ref><ref name="urlBoeing Has Patented a Plasma ‘Force Field’ to Protect Against Shock Waves">{{cite web |url=https://www.sciencealert.com/boeing-has-patented-a-plasma-force-field-to-protect-against-shock-waves |title=Boeing Has Patented a Plasma 'Force Field' to Protect Against Shock Waves |format= |date=30 March 2015 |accessdate=}}</ref>

[[Michio Kaku]] proposes force fields consisting of three layers. The first is the high-powered plasma window which can vaporize incoming objects, block radiation, and particles. The second layer will consist of thousands of laser beams arranged in a tight lattice configuration to vaporize any objects that managed to go through the plasma screen, by the laser beams. The third layer is an invisible but stable sheet of material like [[carbon nanotube]]s, or [[graphene]] that is only one atom thick, and thus transparent, but stronger than steel to block possible debris from destroyed objects.<ref name="Alderson">{{cite web |url=https://medium.com/predict/creating-force-fields-a207f49b8421 |title=Creating Force Fields. A simple idea. Nearly impossible&nbsp;... &#124; by Ella Alderson &#124; Predict &#124; Medium |format= |date=4 October 2020 |accessdate=}}</ref><ref name="urlPhysics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel - WSJ">{{cite web |url=https://www.wsj.com/articles/SB120534908289431017 |title='Physics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel' - WSJ |format= |accessdate=}}</ref>

== Plasma valve ==
A related technology is the <!-- [[plasma valve]] relink if separate article has been created -->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 technicians time to shut off the particle beam in the accelerator and slowly recompress the accelerator ring to avoid damage.

== Properties ==

The physical properties of the plasma window vary depending on application. The initial patent cited temperatures around {{convert|15,000|K|C F}}.

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&nbsp;kW/cm) in the diameter of a round window.{{citation needed|date=October 2012}}

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

== Similarity to fictional "force fields" ==

In [[science fiction]], such as the [[television]] series ''[[Star Trek]]'', a fictional technology known as the "[[Force field (technology)|force field]]" is often used as a device. In some cases it is used as an external "door" to [[hangar]]s 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 [[Magnetohydrodynamics|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.<ref>{{cite web|url=http://www.startram.com/resources|title=StarTram2010: Maglev Launch: Ultra Low Cost Ultra High Volume Access to Space for Cargo and Humans|publisher=startram.com|accessdate=April 28, 2011|archive-url=https://web.archive.org/web/20170727013646/http://www.startram.com/resources|archive-date=July 27, 2017|url-status=dead}}</ref>

== See also ==
* [[Tractor beam]]

== Other sources ==
* BNL Wins R&D 100 Award for 'Plasma Window'<ref>{{cite web|url=http://www.bnl.gov/bnlweb/pubaf/bulletin/1996/bb101896.pdf |title=BNL Wins R&D 100 Award for 'Plasma Window' |publisher=Bnl.gov |accessdate=2015-05-04}}</ref>
* Ady Hershcovitch. Plasma Window Technology for Propagating Particle Beams and Radiation from Vacuum to Atmosphere<ref>{{cite web|url=http://www.nasatech.com/Briefs/May98/0598ETB1.html |title=Plasma Window Technology for Propagating Particle Beams and Radiation from Vacuum to Atmosphere – Nasa Tech Briefs :: NASA Tech Briefs |publisher=Nasatech.com |date=2007-05-15 |accessdate=2015-05-04}}</ref>

== Bibliography ==
* 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

== References ==
{{reflist}}

== External links ==
* [http://www.nasatech.com/Briefs/May98/0598ETB1.html Official article by Ady Hershcovitch] – Inventor of the Plasma Window.
* [http://www.bnl.gov/bnlweb/pubaf/pr/1996/bnlpr080896.html Brookhaven Lab Wins R&D 100 Award for the "Plasma Window"]
* [http://www.bnl.gov/world/ Brookhaven National Laboratory] – Where the Plasma Window was invented
* [http://www.bnl.gov/bnlweb/pubaf/pr/2001/bnlpr121101b.htm News on the Plasma Window]
* {{US patent|5578831|Plasma Window Patent}}
* [http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/search-bool.html&r=9&f=G&l=50&co1=OR&d=ptxt&s1='Plasma+Window'&s2='Ady+Hershcovitch'&OS=%22Plasma+Window%22+OR+%22Ady+Hershcovitch%22&RS=%22Plasma+Window%22+OR+%22Ady+Hershcovitch%22 Plasma Valve Patent]

{{Emerging technologies|other=yes}}

[[Category:Plasma technology and applications]]