In early November of 2005 Chris and his team started to give Project Thumper got it's next major set of upgrades with the addition of a Discharge Table. The original table is just an old wooden workbench we salvaged from the basement of the new lab. We added a layer of nice new MDF for the top for reinforcement.

We had wanted a discharge table for quite a while but we wanted to go through a couple prototype tables before settling on a final design. We knew we wanted to build the finished table from Makrolon and it's far too expensive to built mock-ups with. Makrolon is the ballistics rated clear plastic sheetings used for "bullet proof glass" in banks and convenience stores.

The other major holdup for building a discharge table was the sourcing of suitable insulators for mounting the massive copper buss rails. Thanks to a wonderful donation from Jim The Electrician those arrived on our doorstep (though he had no idea at the time that we would use them for such a purpose).


Thankfully, Jim's insulators were a perfect match for our rails.


The insulators were firmly bolted to the table, then we cut the copper buss and bolted it to the top of the insulators. Given that Thumper's main power cabinet has 500MCM main power rails we planned on using 500MCM for the interconnects to the table. To keep the losses down we kept the interconnects as short as possible and doubled them up into two pairs.


Here's a very early test setup during construction. 500MCM cable is massive and takes a pair of large dedicated people to put a smooth bend in. This is what happens if one ISO standard moron just grabs a piece of it and kludges it in for a test.


Here's a shot showing the whole system under construction.


This is an excellent (and rare) shot showing the cabinet from its rear access panel in good detail. You can see the rails, supports, and output taps. Note the charging HV supply on the bottom shelf.


Here you can see a finished set of connections for one pair of the 500MCM interconnect cables. The length is as short as we could make it and still be able to bend the wire smoothly. Despite this, the massive electromagnetic forces are so great that even with using a cheater bar to tighten the lugs, they will work themselves loose in about 50 discharges. If you forget to do a full systems check they can (and have) had one end fall right out of the connector.

We knew of this problem and because of that all of the main cable terminations are oriented downwards. This way a cable cannot remain loose and still sit in the connector (as it would if it were mounted vertically or possibly even horizontally). Were that to happen the cable would arc and cause problems. This way, the worst that can happen is a cable falls out and you have a positive visual indicator of a problem.



Here are the nice smooth finished interconnect cables.


And of course, yet another set of advanced refinements to the classic "Broker Enhanced High Voltage Safety Switch"! Here we're using an insulated guide and support made from a scrap piece of Lexan, an eye-bolt, and some heavy-duty parachute cord. No expense was spared in this incredibly well funded project.



Note the discharge ablations in the bottom power rail. If you look closely at this there's very interesting patterns etched into the surface. There's also several different metals fused together here as a result of various objects placed in the discharge path.

This is also the point when we shot the well circulated video of Thumper blowing various things to bits. Here is the video, with an explanation of what you're actually seeing.

Ok, now the first thing you have to understand is everything you're seeing is in pairs. First you're seeing the actual explosion in real-time, then you're seeing the same explosion again in slow motion. Here is a list of what we're blowing up and what to notice.

All explosions are under identical conditions of charge, 1,600VDC.
1. 00:06 Piece of heavy gauge "plumbing" solder.

2. 00:08 Solder in slow-mo, note that it completely disintegrates into a could of gas and a shower of molten lead. This is common for many of the things we put on Thumper.

3. 00:14 Small Steel Juice Can. We like to use the small Steel cans because they're made from a rolled sheet of heavy gauge steel as opposed to the much thinner aluminum used in pop cans. Steel cans tend to make a much more impressive shower of sparks whereas the thin aluminum cans pretty much just vaporise leaving only a few small pieces.

4. 00:16 Small Steel Can - Slow-mo.

5. 00:20 Standard Aluminum thin walled pop can. Note that you can hear a small piece of the can hitting the concrete floor after the explosion.

6. 00:23 Standard pop can slow-mo. Note the shower of molten pieces of can. The large gas cloud includes any remnants of the can's original contents (and nontrivial amounts of the can itself which is considered a Bad Thing(tm) to breathe). This is especially good when the can once held something particularly aromatic, grape soda works best.

7. 00:30 Another juice can, because they're fun.

8. 00:31 Juice can slow-mo.

9. 00:37 a 1' long piece of 12AWG Essex brand high temperature magnet wire. Note that unlike everything else it doesn't detonate immediately when the connection is made. this is because it has a thin coating of insulation on it. We had to smack it a few times to scratch through the insulation. Once that layer is scraped away however....boom. The entire length of the wire vaporises and because of the longer area, the explosion is much louder than our typical ones.

10. 00:39 Wire in slow-mo, nothing remains.

11. 00:45 Pop can with a sheet hanging as a backdrop. Because the deafening sound of the explosion simply doesn't convey well in the video we decided to make it more visual by hanging a sheet so you can see the expanding shockwave. The video still doesn't really do it justice. The explosion is so powerful that you can set Thumper up in a gymnasium and feel the shockwave in your chest when standing on the other side of the room.

12. 00:49 Sheet demo pop can slow-mo.

13. 00:58 Pop can in darkness to show the shower of molten metal.

14. 01:00 Pop can in darkness slow-mo.

15. 01:05 Steel juice can in darkness, note the much larger shower of sparks and the different sound of the explosion.

16. 01:07 Steel juice can in the dark, slow-mo.

17. 01:10 This one was just for kicks. We placed 20mL of Acetone into a pop can before firing Thumper through it. The fireball is a fun time. :)

18. 01:14 Pop can acetone slow-mo.

Who says Physics isn't phun!