Re: Spinners, was coil pictures


So does this mean that the RF at the tips ionizes the atmosphere and then 
repells the ions?  If this is true, that probably implies that in a hard
vacuum that the spinner would stop.  Correct?


Right, you don't even need a "hard" vacuum to lower reaction force to very 
small values. 1milliTorr would in most cases be sufficient. (I've actually 
tried this in a limited way).

The ususal explaination is that the electric field is high enough to strip 
the electrons off of the  atoms. If the spinner points are positive then 
the electrons just jump right onto the spinner leaving a positively 
charged ion cloud around the spiiner tip. Since the Ions are relatively 
heavy they can exert a repelling force on the tip - so the thing spins. If, 
on the other hand, the spinner is negative, electrons fly away from the 
tips but then attach to the (especially O2) various molecules in air. This 
makes negative ions from which the tips are repelled. 

As a side note, under some circumstances, it turns out that you can 
actually make a spinner go backward. I don't understand the physical 
process yet, but I've done it experimentally. YOu need fairly high voltages
, say 40-50kv and frequencies of 100-1000Hz depending on the size of the 
spinner and it's local environment. It's quite unusual. I've never found 
this anywhere in the literature... anyone?

-Ed Harris