That is interesting Jones. The singing bowl demonstrates the principle that high quality sonic resonators can exist even with the interaction of air sapping away energy. I did some work with mechanically tuned strips of metglass used in anti theft applications. These cute little strips were tuned to 58 kilohertz and exhibit a Q of 300. The net real part of the pole was still fairly wide so the decay of the resonant frequency occurred within a few milliseconds. That is long enough to distinguish these tags from other natural signals.
I guess most of us are familiar with quartz crystals which have a vast Q in many cases well over 10,000. They are typically in contact with air inside their cases, so perhaps the vacuum would only result in an incremental improvement to the mechanical decay. The cold cathode idea you mention does not ring any bells in my head. (pun intended) Perhaps you should follow up on that idea and see if it has legs. Dave -----Original Message----- From: Jones Beene <[email protected]> To: vortex-l <[email protected]> Sent: Tue, Oct 1, 2013 1:53 pm Subject: RE: [Vo]:Sound in a Vacuum Dave, Speaking of theimplications of “sound in a vacuum”, or lack thereof - one possibilityof interest which may have promise for gain (Maxwell’s demon type ofgain) involves the so called “singing bowl” phenomena. These bowls can producesustained ringing for extended periods but are of course not gainful inthemselves (despite the apparent rise in frequency). http://www.youtube.com/watch?v=9e6oA02wk94 A tuning fork could substitutein this concept - but imagine such a bowl in vacuum, as you suggest. Now –however - the intent of this virtual experiment is that the sustainedvibrations are applied in the context of a cold cathode. So, also imagine that thebowl-in-a-vacuum has a coating of graphene (or other low work function electronemitter) and that the bowl vibrations are used to break up “space charge”which is a limiting factor for cold cathode emission. BTW here is the favoredcold cathode material – a bed of CNT http://techlinkcenter.org/summaries/cold-cathode-low-emission-threshold-and-high-current-density Given that ballistic electronshave a minimum potential which may exceed the work required to emit them if thespace charge can be bypassed – there is the possibility of converting mechanicalvibrations to energy, and thereby extracting ambient heat from the emitter asgain, which also makes the emitter more conductive for a bit of positive feedback… … or not. From:David Roberson The thermal power exiting each square centimeter of surface areais well within reason when 10 micrometer material is used and should not causea meltdown according to preliminary figures.
