A small-scale ion thruster of 18 mm in diameter for space propulsion has been developed and tested. Microwave discharge plasma is produced by a star-type antenna. Two tests were carried out. First, in order to optimize the ion source configuration, we measured the ion saturation current on various conditions measured for the indicator of the performance of an ion source. Next, to estimate the thrust, the ion beam was extracted and extracted ion beam current was measured with obtained optimization configuration. The maximum ion saturation current of 45 mA was obtained at At gas flow rate of 1.4 seem and input microwave power of 28 W. The maximum extracted ion current of 22 mA was obtained at Xe gas flow rate of 0.6 seem and input power of 18 W. (c) 2006 Published by Elsevier B.V.