The abundance ratio of the doubly charged ions in an ion thruster plume was measured in order to estimate the thrust and validate a numerical simulation code for lifetime validation of ion thruster. An E×B probe was used for the estimation of the ratio of doubly charged ions to singly charged ions. The ratio of doubly charged ions to singly charged ions is 0.04 at an incident microwave power of 8 W and a mass flow rate of 20 μg /s. The ratio is decreased with increase in mass flow rate. This is because the increase in mass flow rate leads to the decrease in mean free path, and electrons get less energy from the microwaves.The E×B probe can estimate the ion velocity and the average velocity of the accelerated ions is estimated as 3.7×10 4 m/s at a screen voltage of 1000 V, which is reasonable compared to the theoretical value.
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