Mission advantages of constant power, variable Isp electrostatic thrusters

Summary of Mission RequirementsEach of the mission examples demonstrated how aconstant power, variable Isp system provided missionbenefits compared to existing Hall or ion propulsionsystems. The Isp range and required fuel throughputfrom each mission is shown in Table 8. Thedevelopment of an ion or Hall thruster for VIPSapplications requires efficiency and fuel throughputimprovements at throttling conditions beyond thedemonstrated envelopes. The Isp variation is mainlyprovided by changing the accelerating voltage of thedevice. Consequently, power processing units need tobe designed to handle this change in voltage but still Table 7. Europa Orbiter,negative C3 ion and Hall results.Staged vs Non- 5 Hall / 3 Non- _ Hall / 2 Non-Staged Hall/IonSystems forEuropaOrbiter/LanderIonStagedfrom ref.20Launch MassGeocentric dryStg MassGeocentric StgTank MassGeocentric stgIspGeocentric AVGeocentric FuelMassmass at escapeescape mass lessstageHeliocentric IspEqv.Heliocentric AVHeliocentric FuelMassHeliocentricTank Massdry Helio SEPsys twith solarArrays)Mass at Jupiter 1927 kgMnet Jupiter 1056 kgMnet Europa 453 kg_chem AV=2.7km/s)Added PayloadMassLow Isp Fuel Throughput /thrusterHigh Isp Fuel Throughput /thruster3735 kg371 kg132 kg18005591 m/s1014 kg2721 kg2350 kg31006033 m/s423 kg55 kg871 kgStaged,Five 3.4kWVariableIsp IonThrusters3735 kg0 kg132 kg18005591 m/s1014 kg2721 kg2721 kg31006033 m/s490 kg64 kg