Editing Hall-effect thruster (section)

==== Krypton ====
[[Krypton]] is another choice of propellant for Hall thrusters. Xenon has an ionization potential of 12.1298 eV, while krypton has an ionization potential of 13.996 eV.<ref name="lenntech">{{Cite web|title=The elements of the periodic table sorted by ionization energy|url=https://www.lenntech.com/periodic-chart-elements/ionization-energy.htm|access-date=28 April 2021|website=www.lenntech.com}}</ref> This means that thrusters utilizing krypton need to expend a slightly higher energy per mole to ionize, which reduces efficiency. Additionally, krypton is a lighter ion, so the unit mass per ionization energy is further reduced compared to xenon. However, xenon can be more than ten times as expensive as krypton per [[kilogram]], making krypton a more economical choice for building out [[Satellite constellation|satellite constellations]] like that of [[SpaceX]]'s [[Starlink]] V1, whose original Hall thrusters were fueled with krypton.<ref name="auto" /><ref name=":0" />