Re: Z-Machine Sparkage

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

Original poster: "Bert Hickman by way of Terry Fritz <teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Ken and all,

The Z-Machine is without a doubt the world's largest pulse generator, 108 
feet in diameter and 20 feet high. It consists of three circular concentric 
sections. The outermost ring (not visible in the picture) houses 36 nearly 
identical Marx generators capable of storing over 11 million joules. The 
outer ring holding the Marx generators holds 540,000 gallons of Shell Diala 
AX oil.

Inside this ring is an inner swimming pool-like ring containing 600,000 
gallons of deionized water. This section also houses a series of 
water-insulated high voltage combination capacitors and transmission used 
for intermediate energy storage and low impedance pulse transfer. Finally, 
there's an innermost circular section - this is where all the energy 
ultimately goes. The central experimental chamber is operated in a high 
vacuum. The vacuum is necessary to provide sufficient insulation for the 
final MITL (Magnetically Insulated Transmission Lines) that lead to the 
central experiment section - where the BIG bang eventually goes!

Each Marx generator consists of sixty 1.3 uF capacitors charged in parallel 
to 80-90 kV. Each of these can deliver up to 5.7 million volts into a low 
impedance intermediate energy storage combination Capacitor/Transmission 
Line (C/TL) having a characteristic impedance of about 4 ohms. The C/TL's 
use deionized water as the main dielectric. Water is used for several 
reasons - it has a relatively high dielectric constant, it's an excellent 
insulator for short intervals, and once the experiment is over it can 
harmlessly break down to safely dissipate residual energy from the system. 
During pulse storage and transmission, the peak E-field across the water 
dielectric is about 200 kV/cm.

Once the Marx generators have charged the intermediate water C/TL to 5 MV 
(in about 1 uSec), precision laser-triggered spark gaps switch this stored 
energy into another series of low-impedance water-insulated transmission 
lines, and then through vacuum (and magnetically) insulated transmission 
lines and self-triggered gas insulated spark gaps, and finally into the 
load. If everything works properly, energy from all 36 Marx Generators ends 
up as one huge 2.5 million volt pulse lasting about 100 nS, delivering 20 
million amps into the load - about 60 terawatts of peak power. For those 
interested in all the gory details, a number of excellent papers on the 
Z-machine can be found in the 11th IEEE Pulsed Power Conference Digest of 
Technical Papers.

Now back to Ken's question:
The Sandia picture shows the middle (deionized water) section of the 
machine during, and after, a shot. The fractal-like Lichtenberg figure 
discharges are from "left over" energy (perhaps 5% or less) being safely 
dissipated to nearby grounded framework once the water has undergone 
dielectric breakdown. However, this occurs long after the humongous main 
pulse has come and gone, and is only an aftereffect. The bright blue-white 
regions underwater are from the 36 laser-triggered gas insulated spark gaps 
that were simultaneously triggered to drive the main pulse into the vacuum 
chamber. Most of the energy from the Marx generators ultimately ends up as 
radiation (heat, light, high energy X-rays) inside the vacuum chamber. And 
part of it also creates an earthshaking BOOM that jolts the entire facility!

BTW, for those who've read this far, some more interesting "sparks and 
arcs" stuff can be found at a new page on my web site. On this page you'll 
see a picture of the world's longest manmade spark (325 feet!), a 1.2 MB 
MPEG of a 345 kV 3-phase air break gang switch opening "hot" (it's gotta' 
be the world's biggest Jacob's Ladder!), an awesome 5.1 MB MPEG of a 
substation arcing, resulting in explosion and fire from a big power 
transformer, and a number of JPEGS showing what happens when a Link Belt 
crane tangles with a 34 kV power feeder, and loses! See these at:
http://205.243.100.155/frames/longarc.htm

Happy pulsing and arcing,

-- Bert --
-- 
--------------------------------------------------
Out-of-Print Physics and Engineering Books and
coins shrunk by ultrastrong electromagnetic fields!
Stoneridge Engineering: http://www.teslamania-dot-com
--------------------------------------------------

Tesla list wrote:
>Original poster: "Crow Leader by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><tesla-at-lists.symmetric-dot-net>
>Can anybody explain what is happening in this pic? I've seen it before, and
>the theme is something impressive is going on, but it's never explained.
>What is shown? Why do the sparks look like they can out over some surface,
>like on water or something?
>KEN
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Tuesday, April 08, 2003 1:28 PM
>Subject: Z-Machine Sparkage
>
>  > Original poster: "Matt Skidmore by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <fox-at-woozle-dot-org>
>  >
>  > This page has more to do with producing electricity than anything else.
>  > but, it has an interesting picture of what looks like huge arcs coming off
>  > their equipment.
>  >
>  >
>http://www.sandia.gov/news-center/news-releases/2003/nuclear-power/Zneutrons
>.html
>  >
>  > this image is over a meg
>  >
>http://www.sandia.gov/news-center/news-releases/2003/images/jpg/zmachine.jpg
>  > good sparkage in interesting patterns
>  >
>  >
>  >
>
>.