Study on Magnetized RF Discharge with Very Small-Diameter

Abstract

To investigate characteristics and estimate propulsion performance of a high-density radio frequency plasma with a very small diameter, we have developed the Small Helicon Device (SHD) and measured an electron density n e , an ion velocity v i and an emission intensity of Ar II under various conditions such as a discharge diameter (down to 3 mm), a mass flow rate and a gas species. Using quartz discharge tubes with inner diameter (i.d.) of 3, 10, 20 mm with an Ar gas, n e of (2.5 -6) 10 12 (estimated from optical measurement), 2.5 10 12 and 2.0 10 12 cm -3 , respectively, at -40 mm downstream from an excitation antenna was obtained. Using the 20 mm i.d. tube with a H 2 gas, v i 40 km/s was achieved in the presence of the magnetic field gradient.