Editing Magnetometer (section)

====Metastable helium-4 scalar magnetometer====
Magnetometers based on [[helium-4]] excited to its metastable triplet state thanks to a plasma discharge have been developed in the 1960s and 70s by [[Texas Instruments]], then by its spinoff Polatomic,<ref>{{Cite web |title=Polatomic - Welcome |url=http://www.polatomic.com/ |access-date=2022-05-11 |website=www.polatomic.com}}</ref> and from late 1980s by [[CEA-Leti: Laboratoire d'électronique des technologies de l'information|CEA-Leti]]. The latter pioneered a configuration which cancels the dead-zones,<ref>{{Cite journal |last1=Leger |first1=Jean-Michel |last2=Bertrand |first2=François |last3=Jager |first3=Thomas |last4=Le Prado |first4=Matthieu |last5=Fratter |first5=Isabelle |last6=Lalaurie |first6=Jean-Claude |date=2009-09-01 |title=Swarm Absolute Scalar and Vector Magnetometer Based on Helium 4 Optical Pumping |journal=Procedia Chemistry |series=Proceedings of the Eurosensors XXIII conference |language=en |volume=1 |issue=1 |pages=634–637 |doi=10.1016/j.proche.2009.07.158 |issn=1876-6196|doi-access=free }}</ref> which are a recurrent problem of atomic magnetometers. This configuration was demonstrated to show an accuracy of 50 pT in orbit operation. The [[European Space Agency|ESA]] chose this technology for the [[Swarm (spacecraft)|Swarm mission]], which was launched in 2013. An experimental vector mode, which could compete with fluxgate magnetometers was tested in this mission with overall success.<ref>{{Cite journal |last1=Léger |first1=Jean-Michel |last2=Jager |first2=Thomas |last3=Bertrand |first3=François |last4=Hulot |first4=Gauthier |last5=Brocco |first5=Laura |last6=Vigneron |first6=Pierre |last7=Lalanne |first7=Xavier |last8=Chulliat |first8=Arnaud |last9=Fratter |first9=Isabelle |date=2015-04-25 |title=In-flight performance of the Absolute Scalar Magnetometer vector mode on board the Swarm satellites |journal=Earth, Planets and Space |language=en |volume=67 |issue=1 |pages=57 |doi=10.1186/s40623-015-0231-1 |bibcode=2015EP&S...67...57L |s2cid=55990684 |issn=1880-5981|doi-access=free }}</ref>