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Performance of a 100 kY class, applied field ?IPD thruster was evaluated and sensitivities of discharge characteristics to arc current, mass flow rate, and applied magnetic field were investigated. Thermal efficiencies as high as 60%. thrust efficiencies up to 218, and specific impulses of up to 1150 s were attained with argon propellant. Thrust levels up to 2.5 N were directly measured with an inverted pendulum thrust stand at discharge input powers up to 57 kY. It was observed that thrust increased monotonically with the product of arc current and magnet current.

N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n Lewis Research CenterCleveland, Ohio 44135 SUMMARY F u t u r e , l a r g e E a r t h o r b i t a l s p a c e c r a f t c o u l d b e n e f i t from a r c j e t systems i n t h e 2 t o 5 kW power range f o r a v a r i e t y o f a p p l i c a t i o n s i n c l u d i n g s t a t i o n k e e p i n g , o r b i t a d j u s t m e n t s , and l o g i s t i c s . The a r c j e t power processor r e p r e s e n t s t h e system element w i t h t h e l a r g e s t mass and most i m p a c t i v e system i n t e r f a c e s . T h i s paper d e s c r i b e s t h e i n i t i a l d e s i g n and e v a l u a t i o n o f a 5 k W 1 k W design l a b o r a t o r y a r c j e t . a r c j e t power e l e c t r o n i c s breadboard which as been i n t e g r a t e d w i t h a m o d i f i e dA s i n g l e stage, 5 kW f u l l b r i d g e , p u l s e w i d t h modulated (PWM), power c o n v e r t e r was developed which was phase s h i f t r e g u l a t e d . The c o n v e r t e r used metal o x i d e semiconductor f i e l d e f f e c t t r a n s i s t o r (MOSFET) power switches and i n c o r p o r a t e d c u r r e n t mode c o n t r o l and an i n t e g r a l a r c j e t p u l s e i g n i t i o n c i r c u i t . The unoptimized power e f f i c i e n c y was 93.5 and 93.9 p e r c e n t a t 5 k W and 50 A o u t p u t a t i n p u t v o l t a g e s o f 130 and 150 V , r e s p e c t i v e l y . L i n e and l o a d c u r r e n t r e g u l a t i o n a t 50 A o u t p u t was w i t h i n 1 p e r c e n t . The c o n v e r t e r p r o v i d e d up t o 6.6 k W t o t h e a r c j e t w i t h s i m u l a t e d ammonia used as a p r o p e l l a n t .

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