Don't you guys have a term for that?
Posted on 05/02/2009 6:15:47 PM PDT by Maelstorm
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A bulk glass with high breakdown strength and high dielectric constant would make an ideal candidate for the next generation of high energy density storage capacitors to power more efficient electric vehicles, as well as other portable and pulsed power applications.
The highest dielectric breakdown strengths for bulk glasses are typically in the 4-9MV/cm range. The breakdown strength for the tested samples were in the 12MV/cm range, which in conjunction with a relatively high permittivity, resulted in energy densities of 35 J/cm3, as compared to a maximum energy density of 10 J/cm3 for polypropylene, the most common dielectric for pulsed power applications.
“For a bulk glass, this is extraordinary,” says Nick Smith, a Ph.D. candidate in materials science and engineering at Penn State, who is lead author on the report and performed the testing. Smith used samples of 50 micron-thick commercial glass, which he etched for testing with hydrofluoric acid until the samples were only 10-20 microns thick. The resulting glass was so thin it could be flexed like a piece of plastic film, yet so delicate it could easily disintegrate if mishandled. The thinner the glass, the more electric field can be applied before failure.
The etched glass was placed in a polymer fluid for testing and up to 30,000 volts were applied. When the breakdown point was reached, electricity began to flow through the glass suddenly, with a flash and a bang that resembles a lightning bolt conducting through air. The polymer fluid was used to contain the lightning. In each case, failure occurred within 40 to 80 seconds.
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(Excerpt) Read more at sciencedaily.com ...
Think of what would happen in a traffic accident if they all broke at once!
Don science ping
And thus is the Leyden jar rediscovered.
“A really bad gift idea for me” ping.
Don't you guys have a term for that?
Will that "lightening gun" brighten my teeth, or make Obama look more white?
They were never lost. They also have never had 10-20 microns thick dielectrics with breakdown in the 4-9MV/cm range and energy densities in the 35 joules per cubic cm.
barium boroaluminosilicate glass-
Interesting piece, but I fail to see how it is useful as a weapon, as implied. Sounds like a meltdown when it fails.
There are a lot of “dangerous” capacitors. I still have some wonderfully stable high voltage pyronal capacitors. But I also respect them, they can develop a potentially lethal voltage just being stored without a shorting wire. They have almost no leakage. Suspect they have a much better dielectric value than the polymer the article references.
I will leave that type of thing to someone with a higher pay grade than his.
LOL! Good point!
"yep,he's gotta whole case of em this time"
My point was that the more things change the more they stay the same. For energy storage, after the glass-dielectric Leyden jars came all sorts of other dielectrics: oil, oil-filled paper, various plastics, ceramics, oxide films (electrolytic) ... and now ... drum roll please ... glass again.
I will admit that the glasses are different today, but I won’t admit that the breakdown strengths are all that different from historical glasses. The thickness just amounts to a choice in operating voltage. The dielectric constants are a lot higher today, and with them come higher energy densities.
Does it require Robert DeNiro to captain your airship as in “Stardust?” (great movie!)
Nothing new. Captain NEMO used them on his Nautilus sub in the books 20000 LEAGUES UNDER THE SEA and THE MYSTERIOUS ISLAND. The weapons fired an electrically charged glass ball.
Would a random cosmic ray strike through the dielectric induce a permanent fault? Would shielding be required?
You’re 0.11 gigawatts short. And that’s what’s input into the flux capacitor.
Excuse me, I have to return to 4053 and feed my Eloi.
Old news. The 'Lightning Harvest' guys on the zot threads did this long ago.
The thickness determines the capacitance. Minimizing the distance between plates of a capacitor maximizes the charge that can be stored at a given voltage. This is because the electric field between two large charged sheets is independent of their separation, and hence the voltage ( for a fixed charge ) is proportional to the separation.
I don't believe the statement in the article that the thinner samples have a greater breakdown voltage is correct. It's certainly inconsistent with the expression of breakdown limits in V/cm, which is a field strength.
Maybe what they mean is that with thinner samples you can apply a greater field strength with a given voltage, and thus test to higher limits.
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