View source for High Power Electric Propulsion

{{update|date=March 2017}}

[[Image:HiPEP thruster working.jpg|thumb|right|375px|HiPEP test]]
'''High Power Electric Propulsion''' ('''HiPEP''') is a variation of [[ion thruster]] for use in nuclear electric propulsion applications.<ref>[http://www.nasa.gov/centers/glenn/about/fs09grc_prt.htm?ncid=txtlnkusaolp00000618 The Glenn Research Center]. NASA.</ref><ref name='Prometheus'>[https://web.archive.org/web/20021227094444/http://www.grc.nasa.gov/WWW/ion/present/hipep.htm HIGH POWER ELECTRIC PROPULSION PROGRAM (HiPEP)]. Glenn Research Center - NASA. 22 December 2008.</ref><ref>{{cite web | url=https://ntrs.nasa.gov/search.jsp?R=20040139476 |title= The High Power Electric Propulsion (HiPEP) Ion Thruster NASA/TM—2004-213194 AIAA–2004–3812}}.</ref> It was ground-tested in 2003 by [[NASA]] and was intended for use on the [[Jupiter Icy Moons Orbiter]], which was canceled in 2005.

== Theory ==
The HiPEP thruster differs from earlier ion thrusters because the [[xenon]] ions are produced using a combination of [[microwave]] and [[magnetic]] fields. The [[ionization]] is achieved through a process called [[Electron Cyclotron Resonance]] (ECR). In ECR, the small number of free electrons present in the neutral gas gyrate around the static magnetic field lines. The injected microwaves' frequency is set to match this gyrofrequency and a resonance is established. Energy is transferred from the right-hand [[Polarization (waves)|polarized]] portion of the [[microwave]] to the electrons. This energy is then transferred to the bulk gas/[[Plasma (physics)|plasma]] via the rare - yet important - collisions between electrons and neutrals. During these collisions, electrons can be knocked free from the neutrals, forming ion-electron pairs. The process is a highly efficient means of creating a plasma in low density gases. Previously the electrons required were provided by a [[Hollow cathode effect|hollow cathode]].<ref>{{Cite web |last=Foster |first=John |last2=Haag |first2=Tom |last3=Patterson |first3=Michael |last4=Williams |first4=George J. |last5=Sovey |first5=James S. |last6=Carpenter |first6=Christian |last7=Kamhawi |first7=Hani |last8=Malone |first8=Shane |last9=Elliot |first9=Fred |date=September 1, 2004 |title=The High Power Electric Propulsion (HiPEP) Ion Thruster |url=https://ntrs.nasa.gov/api/citations/20040139476/downloads/20040139476.pdf |access-date=February 6, 2024 |website=nasa.gov}}</ref>

== Specifications ==
The thruster itself is in the 20-50&nbsp;kW class, with a [[specific impulse]] of 6,000-9,000 seconds, and a propellant throughput capability exceeding 100&nbsp;kg/kW.<ref name='Prometheus'/> The goal of the project, as of June 2003, was to achieve a [[technology readiness level]] of 4-5 within 2 years.

The pre-prototype HiPEP produced 670&nbsp; [[milli-|milli]][[Newton (unit)|newton]] (mN) of thrust at a power level of 39.3&nbsp;kW using 7.0&nbsp;mg/s of reaction mass giving a specific impulse of 9620 s.<ref name='Prometheus'/><ref>[https://ntrs.nasa.gov/search.jsp?R=20040139476] Page 8 of the September 2004 HiPEP report NASA/TM—2004-213194</ref>  Downrated to 24.4&nbsp;kW, the HiPEP used 5.6&nbsp;mg/s of reaction mass giving a specific impulse of 8270 s and 460&nbsp;mN of thrust.

== Project and development history ==

Phase 1 of HiPEP development concluded in early 2003.<ref name=GRC-2004>[https://web.archive.org/web/20040110143547/http://www.grc.nasa.gov:80/WWW/ion/present/hipep.htm ''HiPEP Project'' Jan 2004]</ref> Conceptual Design of the thruster was completed, and individual component testing concluded. A full-scale laboratory thruster was constructed for Phase 2 of the HiPEP's development. However, with cancellation of the Jupiter Icy Moon Orbiter mission in 2005, HiPEP's development also came to a halt.<ref>{{Cite web |last= |first= |date=2019-04-06 |title=Gridded Ion Thrusters |url=https://beyondnerva.com/electric-propulsion/gridded-ion-thrusters/ |access-date=2024-02-07 |website=Beyond NERVA |language=en-US}}</ref> Before cancellation, HiPEP completed a 2000 hour wear test.<ref>{{Cite web |last=Herman |first=Daniel A. |date=2010 |title=Status of the NASA’s Evolutionary Xenon Thruster (NEXT) Long-Duration Test After 30,352 Hours of Operation |url=https://ntrs.nasa.gov/api/citations/20110000522/downloads/20110000522.pdf}}</ref><ref>{{Cite web |last=Williams |first=George J. |last2=Hickam |first2=Tyler A. |last3=Haag |first3=Thomas W. |last4=Foster |first4=John E. |last5=Patterson |first5=Michael J. |date=2005 |title=Preliminary Wear Analysis Following a 2000 h Wear Test of the HiPEP Ion Thruster |url=http://electricrocket.org/IEPC/260.pdf |access-date=February 6, 2024}}</ref>
{{expand section|date=November 2021}}

==See also==
* [[Exploration of Jupiter]]
* [[List of spacecraft with electric propulsion]]
* [[Solar electric propulsion]]

==References==
{{reflist}}

== External links ==
* [https://web.archive.org/web/20021227094444/http://www.grc.nasa.gov/WWW/ion/present/hipep.htm NASA GRC Media Packet on HiPEP].
*{{cite web | url=https://ntrs.nasa.gov/search.jsp?R=20040139476 |title= The High Power Electric Propulsion (HiPEP) Ion Thruster NASA/TM—2004-213194 AIAA–2004–3812}}
{{spacecraft propulsion}}

[[Category:Ion engines]]