Performance of 30-cm ion thrusters with dished accelerator grids

Rawlin, Vincent K.

doi:10.2514/6.1973-1053

Cited by 12 publications

(4 citation statements)

References 7 publications

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“…Highest performance was obtained with Lon optics 3 which had the lowest accelerator -.Id open area fraction, 0.36. These results are similar to trends found in mercury ion thrusters.. (9) . The values of .base lev, e2" discharge chamber losses (190eV/Son) are also co •aparable to results obtained from wall optimized mercury ion thrusters.…”

supporting

confidence: 80%

A 30-cm diameter argon ion source

Sovey

1976

12th International Electric Propulsion Conference

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supporting

confidence: 80%

A 30-cm diameter argon ion source

Sovey

1976

12th International Electric Propulsion Conference

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“…This trendhas also beenobservedfor mercurydivergent field(ref. 21) and xenon ring cusp(ref. 22) thrusters.Comparing the curvesat run hours74 and 566, it was seenthat the discharge propellant efficiency (about0.89,at a dischargevoltageof 28 V) was higherfor the earlierdata than it was (about 0.85)for the laterdata.…”

Section: Test Chronologymentioning

confidence: 99%

Internal erosion rates of a 10-kW xenon ion thruster

Rawlin

1988

24th Joint Propulsion Conference

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SUMMARYA 30 cm diameterdivergent magneticfieldion thruster, developed for mercuryoperation at 2.7 kN, was modifiedand operatedwith xenonpropellant at a powerlevelof lO kH for 567 hr to evaluatethrusterperformance and lifetime. The majordifferences betweenthis thrusterand its baselineconfiguration were elimination of the threemercuryvaporizers, use of a maln discharge cathode witha largerorifice,reduction In discharge bafflediameter, and use of an Ion accelerating systemwith largeraccelerator grid holes. At a xenonion beamcurrentof 5 A the engineproduceda thrustof 0.33 N at a specific Impulseof 4220 sec and an efficiency of 6B percent. Therewas no measurable _r screengrid erosion. However,grid thickness measurement uncertainties, com-,,', binedwlthestimates of the effectsof reactiveresidualfacilitybackground gasesgavea minimumscreengrid lifetime of 7000 hr. Discharge cathodeorificeerosionrateswere measuredwith threedifferent cathodeswith different initialorificediameters.As the initialorificediameter was Increased from thatof the baselinevalue,the erosionrate decreased to near zero_ Threepotential problemswere identified duringthe wear test. Flrst,the upstream sideof the discharge baffleerodedat an unacceptable rate,nearly two ordersof magnitude greaterthanthat of the baselinemercurythruster. Second,two of the main cathodetubesexperienced oxidation, deformation, and failureafter227 and 243 hr of thruster operation.Thesefailuresare believed to be relatedto the cathodestartingtechnique.Third,the accelerator gridimpingement currentwas more than an orderof magnitude higherthan thatof the baseline mercurythruster, implyinga greatererosionrate. The impingement currentincreaseis primarily due to a greaterchargeexchangeIon currentresulting from the higherbeam current; operation at a higherneutral atom lossrate and; to a lesserextent,the higherfacilitypressure.. The chargeexchangeion erosionwas not quantified in this test. Therewere no measurable changesin the accelerator grid thickness or the accelerator grid ho]ediameters. INTRODUCTIONInertgas ion thrustersystemsare beingconsidered for primarypropulsion for near-Earth, cislunar, and interplanetary missions(refs.I to 3). To reducethe specific mass and complexity of ion propulsion systems,it is deslrableto increase the thrustproducedby each thruster. Thls can be accomplished by increasing the ion beam current(propellant flow rate)and/orthe beam voltage (propellant velocity).Increasing the beam voltageincreases the thrust and specificimpulse, but, It also reducesthe ratioof outputthrustto input power. Therefore, it is oftendesirable to increasethe ion beam curr,_nt as muchas possiblewith minimalincreases in the beam voltage. However,unless changesin otheroperating conditions can be made to offsetthe increased beam This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States.

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“…The first thruster used was06 A ybich was a modified 400 series thruster. (13,14, The modifications were a result of performance studies nvol •ring the use of disbed ion optics, a stronger magnetic field ac, a shortened baffle mount. ( 19) The "700" series thr,.ater evolved from the modified "400" series thruster with charges to the thruster external structure, separation of the cathode from the isolator-vaporizer assendil and further modification to th' baffle mount.…”

Section: Apparatus and Proceduresmentioning

confidence: 99%