Re: Breakdown voltages of toroids

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi,

I have noted that negative charges arc or things easier than positive 
charges.  Does this stuff take that into account?

Cheers,

         Terry



At 01:12 AM 12/13/2003, you wrote:
>Hi again Antonio, All,
>(view w/fixed width font)
>
>I thought I'd go through some checks with Javatc against your numbers just 
>for a check. During my check, I found problems on my end of things not 
>related to your numbers (problems when "meters" were selected and gap type 
>styles after this was fixed). I ended up removing the different static gap 
>styles and leaving only a single type (sphere-sphere).
>
>Here's some of your data with Javatc pulled in:
>
>Symmetrical gaps:
>sphere diameter:      5      |Javatc|       10       |Javatc|
>gap spacing:
>0.5              14.3 (17.5) | 16.8 |   15.0 (16.9)  | 17.4 |
>1                26.6 (32.2) | 28.9 |   28.6 (31.6)  | 30.8 |
>1.5              37.4 (46.1) | 38.8 |   41.3 (45.8)  | 42.7 |
>2                47.0 (58.3) | 47.3 |   53.2 (59.3)  | 53.5 |
>
>Javatc uses the equations shown in William Norths paper.
>For field strength used with Norths equations, Javatc uses:
>
>Field Strength = p * ( B / ( C + ln ( p * d)))
>where
>    p = pressure in Torr (mm Hg). For air, this value is 760
>    B = 365 Vcm-1 Torr-1
>    C = ln( A / ln ( 1 + 1 / gamma))
>    d = gap width
>where
>    gamma = 0.095 (secondary ionization coefficient)
>    A = 14.6 cm-1 Torr -1
>
>
>Trying some values at the end of the table for symmetrical gaps:
>Spheres with 200 cm:
>Spacing:               | -----Javatc----- |   (volts)
>70        1694 (1560)  | 1226 -at- 17.5kV/cm -at- 391 gradient |
>80        1878 (1730)  | 1346 -at- 16.8kV/cm -at- 349 gradient |
>90        2051 (1900)  | 1456 -at- 16.2kV/cm -at- 317 gradient |
>100       2214 (2050)  | 1559 -at- 15.6kV/cm -at- 291 gradient |
>
>Your values assume Emax=30kV/cm. Why?
>I'm assuming Paschens curve ideal?
>
>Antonio, thanks for doing all you do! You keep us on our toes! BTW, Inca 
>is getting to be quite the program! The field plots are real nice (and fast!).
>
>Take care,
>Bart