Initial Experiments on a Dual-Stage 4-Grid Ion Thruster for Very High Specific Impulse and Power

Abstract

A new and innovative type of gridded ion thruster, the “Dual-Stage 4-Grid” or DS4G concept, has been proven under laboratory conditions under a preliminary research, development and test programme. The DS4G concept is able to operate at very high specific impulse, power and thrust density values well in excess of conventional 3-grid ion thrusters at the expense of a higher power-to-thrust ratio. A small low-power experimental laboratory model was designed and built, and its performance was measured during an extensive test campaign. The principal goals of the initial laboratory experiment were to prove the practical feasibility of the overall concept, demonstrate the performance predicted by analytical and simulation models, and investigate critical design parameters and technological challenges. In the present paper, the basic concept of the DS4G ion thruster is presented, along with the design, operating parameters and measured performance obtained from the first and second phases of the experimental campaign. Finally, the implications of these findings for future gridded ion thruster developments and future mission applications are addressed.