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Re: [TCML] bottle caps

On 8/1/16 12:05 AM, undisclosed recipient via Tesla wrote:

If they are or are not is moot…. the amount of power lost is massive…..
I could never eliminate the corona on the jars.
I had 36 “peanut butter” style jars with plastic lids which prevented flashover, but the coil still didn’t perform as well as with solid state caps.
but is it dielectric loss in the glass or corona loss that is the dominant loss mechanism. 

microwave101.com has some data
http://www.microwaves101.com/encyclopedias/miscellaneous-dielectric-constants
borosilicate glass is epsilon 4.3, tan(d) of 0.0047
soda lime glass is given as epsilon 6.0, tan(d) of 0.02  which is higher.
http://www.microwaves101.com/encyclopedias/glass-materials

comparing to PTFE which has epsilon 2.1 and tan(d) of 0.00015 to 0.0003
An agilent ap note gives tan(d) (at 100 MHz!) for Polyethylene, PTFE,etc of 2E-4, fused silica at 2E-4 as well, and pyrex as 3E-3
but that's at a much higher frequency, and you need to be careful... loss is usually dependent on frequency. 

A 1972 report
http://www.dtic.mil/dtic/tr/fulltext/u2/746686.pdf

(see page 84 for example) shows tan(d) <1E-5 for frequencies below 1 MHz.
However, note also that the loss skyrockets as the glass gets hot (and starts to be more conductive). at 200C, the loss at 1kHz is >10 times worse.
page 91 is a bit worse (mixed silicate glasses)... 0.005 loss tangent at 1 MHz at 21C, 8E-3 at 74C 



On Sep 5, 2016, at 5:50 PM, homerlea--- via Tesla <tesla@xxxxxxxxxx> wrote:


Anyone know if borosilicate glass  used in labs works better(less lossy) than the normal soda lime glass of regular bottles for making salt water capacitors?
Jim Heagy




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