The Composite Force of the  Radiometer

L. Thompson

In my novice testing, I call the radiometer force  a composite force because the transfer of molecular momentum results in the deceleration (cooling) of the individual rarefied gas molecules to give the net macro acceleration of the vanes and harness.  

My testing is in the partial vacuum range of  100 to 300 microns. In this range the radiometer vanes and harness, placed in the vacuum chamber as a control check, show a similar response as in a sealed radiometer.

The variables increase or decrease the net force. Some variables could be: energy input, atomic weights of the gases, vane spacing, shape and type of the surfaces, and the degree of vacuum. 

In the complexities of the rarefied gas reactions is also a simplicity: the radiometer vanes rotate in response to the input of energy or to the taking out of energy.  In the testing  this simplicity is used to show some characteristics of the resulting composite net force. 

Observations and Testing Notes

1. In a radiometer the net force results in centrifugal acceleration - as the force "pushes" into a lower pressure area. 

2. When the rarefied gas molecules transfer momentum, the gas molecules are cooled, are decelerated, representing the "exhaust side" of the force/power. This cooling takes place with the transfer of molecular momentum into the macro momentum of the vanes. 

3. In the testing the gas molecules are recharged and reused. With the continual input of energy, the gas molecules are trapped to be reused to do work.

4. With a strong halogen light , the vanes spin clockwise then upon cooling spin counter clockwise. Radiant energy now radiated at a faster rate from the carbon black surface, creating an opposite pressure differential.  

This would be similar to the refrigeration effect when a radiometer is taken out of a refrigerator. My understanding of radiant energy is little or no force would be exerted on the radiating mass. Hence it could be possible to also create an imbalance when excess energy would be re-radiated back out of the system to cause the vanes to spin oppositely. 

5. I confirmed with a light weight carbonized aluminum strip hanging with an off center hole on a carbon fiber rod that it was possible to move the strip down the rod.  Extrapolating the weight from a larger aluminum strip the weight was about 0.002 grams. The strip moved first with agitation and then rapidly with full circular motions around and down the rod. 

I feel  oscillations are necessary (from high to low pressure areas) to commence movement. This helps explain why I was not able to have heavier strips move along a rod - though a little back and forth movement took place. It helps explain why the much weightier radiometer vanes on the needle pivot spin easily whereas the aluminum/carbonized strips mounted on a rod showed little motion due to "unbalanced friction" preventing oscillations.  

Yet, if needing further confirmation of the necessity for oscillations, the small, carbonized, very light aluminum strip with its off center hole spun energetically around the rod as it moved down the rod.  The degree of energizing looked to match the radiometer vanes on the application of a strong energy source.

Although this test requires a small mass, I also observe the slip effects could be made to be "channeled" into a directional movement. It seems to me the directional application of a net force from within internal means might be possible. 

I feel slip effects can be enhanced when centrifugal acceleration is included to  enhance the pressures differentials. This could help explain why the well balanced, much weightier radiometer vanes can reach 2000 to 3000 rpm.

Notes 

A.  http://en.wikipedia.org/wiki/Crookes_radiometer

In regard to thermal equilibrium, I feel once vane rotation equilibrium is reached, radiant cooling may be sufficient to transfer excess heat out of the system.  

B. The deceleration of the rarefied gas molecules (now a dead weight until re-energized) is "masked" by the net macro acceleration of the vanes and harness. 

C. Newton's physics, focused on taking apart and quantifying, could "overlook" the composite nature of the radiometer force. I feel this is why a fuller explanation could require  looking at the radiometer as a total process - including the deceleration of the rarefied gas molecules.

 Last edited 11/22/2014. Thanks,  David for "pushing" me to run the testing.  lance@pon.net