Editing Pulsed inductive thruster (section)

== 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>