I'm currently working on a project and trying to sense the thrust being output by an ion thruster.
Right now I am using a faraday cup to measure the Ion count and figuring out the thrust by this reading, but I'd like to have another sensor to check and verify the faraday cup. I was thinking to use some sort of small fan and using the rotation of the fan to figure out the thrust. It's a low amount of thrust so I don't know how practical this idea would be but I did think of two potential options:
Use a small computer fan and remove the electronics from inside of it with the exception of the stepper motor. That way as the fan turns it generates a current from the moving fan and thus I can measure the current to get the speed then go from there to get the thrust.
Just use a fan with nothing inside and use an external encoder/laser and just count the amount of times a marked blade passes by the laser each second.
Any option seem reasonable, or are there better ways of approaching this?