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Re: Skin Effect & Primary Current?

>From: "Fred W. Bach, TRIUMF Operations" <music-at-triumf.ca>
>To: tesla-at-pupman-dot-com
>Cc: music-at-triumf.ca
>Subject: Re: Skin Effect & Primary Current?
>
>>Message-ID: <199607300425.WAA18801-at-poodle.pupman-dot-com>
>>Date: Mon, 29 Jul 1996 22:25:01 -0600
>>To: Tesla-list-subscribers-at-poodle.pupman-dot-com
>>Subject: Re: Skin Effect & Primary Current?
>>
>>From jim.fosse-at-bdt-dot-comMon Jul 29 21:26:44 1996
>>Date: Mon, 29 Jul 1996 06:48:49 GMT
>>To: tesla-at-pupman-dot-com
>>Subject: Re: Skin Effect & Primary Current?
>
>
>   [ snip ]
>   The turn-on time or the rise time
>   of the current in the line-charge pulser fired by triggering the
>   merecury-wetted relay was faster than a nanosecond.  We're talking
>   several hundred volts on a 50-ohm coax line fired into a microwave
>   vacuum-tube (a triode) cathode.  The tube was run in grounded-grid
>   configuration, and the plate circuit was the mouth of the
>   accelerator tube.  So the electrons shot down the tube and got
>   accelerated to a few million electron-volts of energy.  They made
>   really hard x-rays.
>
Fred, Thanks:
	I "know"/have-read-about  coaxial pulse networks and common
grid amplifiers, but have not had the pleasure of building any (yet)
just Hartly oscillators (power; 6L6's, ham radio days) and superregen
receivers.
>
[snip]
> The whole VdG generator (column, belt, motor, controls
>   and th HV top end) was inside a pressure vessel of 20 atmospheres
>   of a mixture of nitrogen and carbon-dioxide gas to suppress tank
>   sparks since the top-end ran at 2 million or more volts DC and the
>   diameter of the tank was under 6 feet.
Wow! at STP (air) what was the discharge distance? If you
know/remember.

>  The top-end HV VdG terminal
>   cathode-pulsing circuit was controlled optically.  The mechanical
>   switching was done by driving motors at the bottom end which drove
>   long lucite rods up alongside the belt up to the top end.  Some
>   other Van de Graaff accelerators used nylon (or similar) cables and
>   pulleys to turn switches and pots at their top ends.  I remember
>   the day several pulley systems were melted by the addition of SF6
>   gas....
Fun in retrospect? I've had several of THOSE days! They have, just,
not made it to my humorous-times list yet.
>
>   The time jitter on the closing of the mercury-wetted relay was plus
>   or minus 25 milliseconds from the time we asked it to fire.  Since
>   we could not do nanosecond timing of the capture of the actual
>   experimental data with that huge kind of slop (!),
The way around natures' limits;)

>>>
>>I'm having visions of an open-air, rotary paddle-wheel, mercury gap
>>here;)   
>
>   Why not put the whole thing in a sealed cavity, motor, contacts,
>   mercury and all?  If physical orientation were a problem for our
>   relay, it ought to be a bigger problem for a motor-driven rotary
>   switch.  A job for a mechanical engineer maybe.
>
I'm sorry Fred,
	I have a tendency to mix my archain humor with discussions. I
was visualizing the absurdity of running an 'open' rotary mercury gap
in today's safety conscience (relative to the 1900's) environment: not
the practical aspects.

	Highest Regards,

	jim