Performance of Radio Frequency Ion Thruster with Polytetrafluoroethylene Propellant Embedded in Discharge Chamber

Exploring solid propellants for electric thrusters can simplify the propellant storage and supply units in propulsion systems. In this study, polytetrafluoroethylene(PTFE), commonly used as a propellant in pulsed plasma thrusters, was embedded in the discharge chamber of a radio frequency ion thruster(RIT-4) to investigate the performance of an ablation-type RIT.Experimental results indicate that PTFE can decompose and ionize stably under plasma ablation within the discharge chamber, producing –C–F– and F– ion clusters that form a stable plasma.By adjusting the length of the PTFE propellant, it was observed that its decomposition rate influences the ion beam current of the thruster. Compared with xenon, PTFE generates an ion plume with a larger divergence angle, ranging from 16.05° to 22.74° at an ion beam current of25 mA, with a floating potential distribution of 8-56 V. Assuming that the proportion of neutral gas in the vacuum chamber matches the ion species ratio in the ion plume, thrust, specific impulse and efficiency parameters were calculated for the RIT-4 with embedded PTFE. Under 50 W RF power, the thrust was approximately 1.02 mN, the specific impulse was around 1236 s and the power-to-thrust ratio was approximately 93.14 W/mN. All results indicate that PTFE is a viable propellant for RIT, but the key is to control the rate of decomposition.