View source for Field mill

{{about|the instrument|other uses|Field mill (disambiguation)}}
[[Image:Field mill.jpg|thumb|right|Field mill installation at the Kennedy Space Center in Florida]]
[[File:Signalverarbeitung-Feldmühle.svg|thumb|signal conditioning inside a field mill. ➀&nbsp;Chopper wheel; ➁&nbsp;sensor plates; ➂&nbsp;base plate; ➃&nbsp;rotary encoder; ➄&nbsp;drive; ➅&nbsp;amplifier; ➆&nbsp;multiplier; ➇&nbsp;low-pass; ➈&nbsp;display]]
[[File:Prinzip-Feldmühle.svg|thumb|Principle in plain view]]
[[File:E-fieldmill operation.png|thumb|Electric Field mill operation]]
A '''field mill''' is a specialized instrument used for measuring the strength of electric fields in the atmosphere, one of the key parameters of  [[atmospheric electricity]]. They are used in the launch criteria for rockets bound for orbit, as well as the now-retired [[Space Shuttle]], to avoid lightning strikes. They are also used in outdoor laboratories for lightning protection equipment to determine favorable experiment conditions,<ref>{{cite video
  | title = KAPOW! Superhero Science
  | url = http://science.discovery.com/videos/kapow-superhero-science-controlled-lightning.html
  | medium = Television Documentary
  | publisher = Discovery Network; Actuality Productions
  |date = 2003}}</ref> or simply to measure the atmospheric electric field away from thunderstorms.

The "mill" is a typical rotating shutter design in the instrument.  It acts as a [[Chopper (electronics)|Chopper]], converting the tiny DC signal of ambient static electricity into a tiny AC signal that is easier to detect without the amplifier's DC bias swamping it.  It can be used on the ground, or deployed airborne and flown through [[Cumulonimbus incus|anvil head clouds]] to make measurements.

== KSC electric field mill network ==
At [[Kennedy Space Center]] (KSC) in Florida, 31 field mills are deployed around KSC and the nearby [[Cape Canaveral Space Force Station]]. Data from the field mills help forecasters determine when electric charge aloft might trigger lightning during a launch.<ref>{{cite web |url=http://thunder.msfc.nasa.gov/validation/validation.html#KSC-EFMN |title=KSC Electric Field Mill Network |publisher=NASA MSFC |url-status=dead |archiveurl=https://web.archive.org/web/20160307112621/http://thunder.msfc.nasa.gov/validation/validation.html#KSC-EFMN |archivedate=2016-03-07 }}</ref>

==References==
<references/>

==External links==
*[http://www.missioninstruments.com/pages/learning/about_fm2.html About Electric Field Mill Operation]
*[http://ghrc.nsstc.nasa.gov/uso/ds_docs/camex4/c4gmipfm/c4gmipfm_dataset.html CAMEX-4 MIPS Field Mill]
*[http://ams.allenpress.com/amsonline/?request=get-abstract&doi=10.1175%2F1520-0426(1994)011%3C0738:AOAFMD%3E2.0.CO%3B2 Application of Airborne Field Mill Data for Use in Launch Support]
*[https://archive.today/20130202150911/http://www.spaceref.com/news/viewpr.html?pid=2194 Florida Airborne Field Mill Research May Improve Launch Weather Criteria]
* http://www.precisionstrobe.com/jc/fieldmill/fieldmill.html Build a homemade field mill
*[http://www.foudre-ineo.com/en/ INEO SUEZ] {{Webarchive|url=https://web.archive.org/web/20230419013014/http://www.foudre-ineo.com/en/ |date=2023-04-19 }}
*[https://web.archive.org/web/20131219194554/http://www.lightning.ece.ufl.edu/ Lightning Research Laboratory&mdash;University of Florida]
*[http://www.kwos.it/joomla/weather-monitoring/all-about-lightning Lightning detection]

{{Meteorological equipment}}

{{DEFAULTSORT:Field Mill}}
[[Category:Meteorological instrumentation and equipment]]


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