Editing Pulsed inductive thruster

[[File:Schemat Pulsed Inductive Thruster.svg|thumb|300px|Cross-section diagram of a pulsed inductive thruster. [1] The gas is puffed inward through a central nozzle, towards the flat electromagnetic coil where it is ionized. [2] The plasma (pink) is then accelerated to the rear by the Lorentz force.]]

A '''pulsed inductive thruster''' ('''PIT''') is a form of [[ion thruster]], used in [[spacecraft propulsion]]. It is a [[plasma propulsion engine]] using perpendicular [[electric field|electric]] and [[magnetic field]]s to accelerate a [[propellant]] with no [[electrode]].

== Operation ==

A [[nozzle]] releases a puff of gas which spreads across a flat spiraling [[induction coil]] of [[wire]] about 1 meter across. A bank of [[capacitor]]s releases a pulse of [[high voltage]] [[electric current]] of tens of kilovolts lasting 10 microseconds into the coil, generating a radial magnetic field. This [[electromagnetic induction|induces]] a circular electrical field in the gas, [[Ionization|ionizing]] it and causing [[charged particle]]s (free [[electrons]] and [[ion]]s) to revolve in the opposite direction as the original pulse of current. Because the motion of this induced current flow is perpendicular to the magnetic field, the [[Plasma (physics)|plasma]] is accelerated out into space by the [[Lorentz force]] at a high exhaust velocity (10 to 100&nbsp;km/s).<ref>Dailey, C. Lee; Lovberg, Ralph H. (July 1993). [https://ntrs.nasa.gov/api/citations/19930023164/downloads/19930023164.pdf "The PIT MkV Pulsed Inductive Thruster"]. NASA CR 191155.</ref>

== Advantages ==

Unlike an [[electrostatic ion thruster]] which uses an [[electric field]] to accelerate only one [[Chemical species|species]] (positive ions), a PIT uses the Lorentz body force acting upon all charged particles within a quasi-neutral plasma. Unlike most other ion and plasma thrusters, it also requires no [[electrode]]s (which are susceptible to erosion) and its power can be scaled up simply by increasing the number of pulses per second. A 1-[[megawatt]] system would pulse 200 times per second.

Pulsed inductive thrusters can maintain constant [[specific impulse]] and thrust efficiency over a wide range of input power levels by adjusting the pulse rate to maintain a constant discharge energy per pulse. It has demonstrated efficiency greater than 50%.<ref name="NuPIT">{{cite conference|last1= Frisbee|first1= Robert H.|last2= Mikellides|first2=Ioannis G.|title= The Nuclear-Electric Pulsed Inductive Thruster (NuPIT): Mission Analysis for Prometheus|date= July 2005|conference= 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit|location= Tucson, Arizona|url=https://trs.jpl.nasa.gov/bitstream/handle/2014/38357/05-1846.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://trs.jpl.nasa.gov/bitstream/handle/2014/38357/05-1846.pdf |archive-date=2022-10-09 |url-status=live|accessdate=July 4, 2017}}</ref>

Pulsed inductive thrusters can use a wide range of gases as a propellant, such as [[water]], [[hydrazine]], [[ammonia]], [[argon]], or [[xenon]], among many others. Due to this ability, it has been suggested to use PITs for [[Mars|Martian]] missions: an orbiter could refuel by scooping [[Carbon dioxide|CO<sub>2</sub>]] from the [[atmosphere of Mars]], compressing the gas and liquefying it into [[storage tank]]s for the return journey or another [[interplanetary mission]], whilst orbiting the planet.<ref>Polzin, Kurt A. (June 2012). [https://ntrs.nasa.gov/search.jsp?R=20120015307 "Pulsed Inductive Thruster Using Martian Atmosphere as Propellant"] ''Concepts and Approaches for Mars Exploration.'' NASA.</ref>

== Developments ==

Early development began with fundamental proof-of-concept studies performed in the mid-1960s. NASA conducts experiments on this device since the early 1980s.

=== PIT Mk V, VI and VII ===

NGST ([[Northrop Grumman|Northrop Grumman Space Technology]]), as a contractor for NASA, built several experimental PITs.

Research efforts during the first period (1965–1973) were aimed at understanding the structure of an inductive current sheet and evaluating different concepts for propellant injection and preionization.

In the second period (1979–1988), the focus shifted more towards developing a true propulsion system and increasing the performance of the base design through incremental design changes, with the build of ''Mk I'' and ''Mk IV'' prototypes.

The third period (1991-today) began with the introduction of a new PIT thruster design known as the ''Mk V''. It evolved into the ''Mk VI'', developed to reproduce Mk V single-shot tests, which completely characterize thruster performance. It uses an improved coil of hollow copper tube construction and an improved propellant valve, but is electrically identical to the Mk V, using the same capacitors and switches.<ref>{{cite conference|last1= Russell|first1= Derrek|last2= Dailey|first2= C.|last3= Goldstein|first3= Wayne|last4= Lovberg|first4= Ralph|last5= Poylio|first5= James|last6= Jackson|first6= Bernard|last7= Lovberg|first7= Ralph H.|last8= Dailey|first8= C. Lee|title= The PIT Mark VI Pulsed Inductive Thruster|date= September 2004|conference= Space 2004 Conference and Exhibit|location=San Diego|doi=10.2514/6.2004-6054}}</ref> The ''Mk VII'' (early 2000s) has the same geometry as Mk VI, but is designed for high pulse frequency and long-duration firing with a liquid-cooled coil, longer-life capacitors, and fast, high-power solid-state switches. The goal for Mk VII is to demonstrate up to 50 pulses per second at the rated efficiency and impulse bit at 200&nbsp;kW of input power in a single thruster. Mk VII design is the base for the most recent ''NuPIT'' (Nuclear-electric PIT).<ref name="NuPIT" />

The PIT has obtained relatively high performance in the laboratory environment, but it still requires additional advancements in switching technology and energy storage before becoming practical for high-power in-space applications, with the need for a nuclear-based onboard power source.

=== FARAD ===

''FARAD'', which stands for ''Faraday accelerator with radio-frequency assisted discharge'', is a lower-power alternative to the PIT that has the potential for space operation using current technologies.<ref>{{cite conference|last1= Choueiri|first1= Edgar Y.|last2= Polzin|first2= Kurt A.|title= Faraday Acceleration with Radio-frequency Assisted Discharge (FARAD)|date= July 2004|conference= 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit|location= Fort Lauderdale, Florida|url=https://massless.info/images/choueiri-jpc-2004-3940.pdf |archive-url=https://web.archive.org/web/20221120111018/https://massless.info/images/choueiri-jpc-2004-3940.pdf |archive-date=2022-11-20 |url-status=live|format= PDF|doi=10.2514/6.2004-3940 }}</ref><ref>{{cite conference|last1= Dankanich|first1= John W.|last2= Polzin|first2= Kurt A.|title=Mission Assessment of the Faraday Accelerator with Radio-Frequency Assisted Discharge (FARAD)|date= July 2008|conference=44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference|location= Hartford, CT|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090001283.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090001283.pdf |archive-date=2022-10-09 |url-status=live|doi=10.2514/6.2008-4517 |hdl= 2060/20090001283|hdl-access= free}}</ref>

In the PIT, both propellant ionization and acceleration are performed by the HV pulse of current in the induction coil, while FARAD uses a separate inductive RF discharge to preionize the propellant before it is accelerated by the current pulse. This preionization allows FARAD to operate at much
lower discharge energies than the PIT (100 joules per pulse vs 4 kilojoules per pulse) and allows for a reduction in the thruster's size.<ref>{{cite thesis|last=Polzin|first=Kurt Alexander|date=June 2006|title=Faraday Accelerator with Radio-frequency Assisted Discharge (FARAD)|type=Ph.D.|publisher=[[Princeton University]]|url=http://www-personal.umich.edu/~ianrit/PIT/PolzinThesis.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www-personal.umich.edu/~ianrit/PIT/PolzinThesis.pdf |archive-date=2022-10-09 |url-status=live}}</ref>

==References==
{{Reflist}}

{{spacecraft propulsion}}

[[Category:Ion engines]]
[[Category:Magnetic propulsion devices]]