DESIGN OF A MODULAR SOURCE CONTACT ION ENGINE.

Abstract : This report covers the design, fabrication and test of a two module engine capable of 20 mlb. of thrust with a grid replacement mechanism. Also included are analyses which calculate the grid erosion rate due to charge exchange ionization, and rocket efficiency penalties associated with high engine weight and off-optimum I sub s design. With the emitter material available for this work representative operational characteristics were: at 4600 sec. I sub s, 62% electrical efficiency and 163 KW/lb.; at 6950 sec. I sub s, 80% electrical efficiency and 190 KW/lb. Propellant utilization was 0.94 or greater. The grid replacement weight is equivalent to a propellant utilization of not less than 90%. Engine weight is 1 Kg/ampere of ion beam. Emitter material currently developed should permit operation with this same engine design at 80% electrical efficiency at 5000 sec. (Author)