Editing Magnetoplasmadynamic thruster (section)

{{short description|Form of electrically powered spacecraft propulsion}}
[[Image:MPD plume.jpg|thumb|right|An MPD thruster during test firing]]A '''magnetoplasmadynamic''' ('''MPD''') '''thruster''' ('''MPDT''') is a form of [[electrically powered spacecraft propulsion]] which uses the [[Lorentz force]] (the force on a charged particle by an electromagnetic field) to generate thrust. It is sometimes referred to as a Lorentz Force Accelerator (LFA) or (mostly in Japan) MPD [[arcjet]].

Generally, a gaseous material is [[ionized]] and fed into an acceleration chamber, where the magnetic and electric fields are created using a power source. The particles are then propelled by the Lorentz force resulting from the interaction between the current flowing through the plasma and the magnetic field (which is either externally applied or induced by the current) out through the exhaust chamber. Unlike chemical propulsion, there is no combustion of fuel.{{Citation needed|date=February 2025}} As with other electric propulsion variations, both [[specific impulse]] and [[thrust]] increase with power input, while thrust per watt drops.

There are two main types of MPD thrusters, applied-field and self-field. Applied-field thrusters have magnetic rings surrounding the exhaust chamber to produce the magnetic field, while self-field thrusters have a cathode extending through the middle of the chamber. Applied fields are necessary at lower power levels, where self-field configurations are too weak. Various propellants such as [[xenon]], [[neon]], [[argon]], [[hydrogen]], [[hydrazine]], and [[lithium]] have been used, with lithium generally being the best performer.<ref>{{Cite web |title=PROPELLANTS |url=https://history.nasa.gov/conghand/propelnt.htm |access-date=2022-11-05 |website=history.nasa.gov}}</ref>

According to [[Edgar Choueiri]] magnetoplasmadynamic thrusters have input [[Power (physics)|power]] 100–500 kilowatts, [[exhaust velocity]] 15–60 kilometers per second, [[thrust]] 2.5–25 [[newton (unit)|newtons]] and [[efficiency]] 40–60 percent. However, additional research has shown that exhaust velocities can exceed 100 kilometers per second.<ref name="alfven.princeton.edu">{{cite web| url = http://alfven.princeton.edu/publications/choueiri-sciam-2009| title = Choueiri, Edgar Y. (2009). New dawn of electric rocket. Next-Generation Thruster| access-date = 2016-10-18| archive-date = 2016-10-18| archive-url = https://web.archive.org/web/20161018201525/http://alfven.princeton.edu/publications/choueiri-sciam-2009| url-status = dead}}</ref><ref name="Choueiri">Choueiri, Edgar Y. (2009) [http://www.nature.com/scientificamerican/journal/v300/n2/full/scientificamerican0209-58.html New dawn of electric rocket] ''[[Scientific American]]'' 300, 58–65 {{doi|10.1038/scientificamerican0209-58}}</ref>

One potential application of magnetoplasmadynamic thrusters is the main propulsion engine for heavy cargo and piloted space vehicles (example engine <math>a^2</math> for [[human missions to Mars]]).<ref name="alfven.princeton.edu"/><ref name="Choueiri"/>