Electric propulsion in 1964 - a status review

Abstract

IntroductionThe year 1964 has not yet brought the ex-pected flight test of an electric thrust engine.However, the development of electric propulsion ,as a new branch of rocket technology has madesignificant progress in many ways. Power effi-ciency, propellant efficiency, and lifetime ofthrustors have increased. Studies of propulsionsystems for specific applications have resultedin realistic appraisals of performance figuresand optimization Schemes.Desirable features of power sources havebeen identified to an extent that guidelines forpower supply development can be specified. Mis-sion studies have further demonstrated the super-iority of electric propulsion systems over othersystems on a number of unmanned and mannedmissions. Most significant, however, is probablythe growing recognition of the fact that the develop-ment of electric propulsion systems should not beshelved until an indisputable requirement arises.Our national space program is evolving under acharter which makes unmanned and manned explor-ation of space a national goal. In this light, elec-tric propulsion is one very promising propulsionsystem of great potentialities. It is not a com-petitor, but a complement to other systems, andit will extend our payload capabilities considerablywith respect to mass, flight times, and missionfeasibility. It should be noted that none of the de-cisive accomplishments in our space program sofar was achieved as fulfilment of an immediaterequirement, but rather in response to thechallenge of a new technology which had comewithin reach.Electrothermal ThrustorsElectrothermal thrustors, because oftheir inherent simplicity in design and operation,are of interest for mission applica'ions which re-quire an optimum exhaust velocity on the orderof 10 000 to 15 000 m sec