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[moved] Very High Voltage Coil Gun

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Travlax1

Wed Mar 12 2008, 04:54PM

Registered Member #1388 Joined: Wed Mar 12 2008, 04:42PM
Location:
Posts: 23

I'm a high school Senior who received a generous donation of a free capacitor. The company has given me several options but I decided to go big and asked for a capacitor similar to the Maxwell Energy Discharge Capacitor (10kv 120uF). I've done some experimenting with just a wall outlet and with some small cap banks, however I was using a classroom model coil that I built that had 18 gauge wire and about 500 turns in the coil. The one I want to build now is made with very low gauge wire and a minimal amount of turns thats powered by the single capacitor. I'm looking for any advice or suggestions that people have as to the construction of the coil, anything I may not be thinking of and also I have been wondering if there are any alternatives to a spark gap for the switch. Thanks, your help is appreciated.

Wolfram

Wed Mar 12 2008, 08:51PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

Moved to Electromagnetic Projectile Accelerators, as the topic fits much better in this subforum.

ramses

Wed Mar 12 2008, 09:06PM

Registered Member #1208 Joined: Thu Jan 03 2008, 05:30PM
Location: Chesterland, OH
Posts: 154

i can almost 100% guarantee that the projectile will saturate, but you could go induction if you don't mind.

you need to make the coil extremely sturdy, because the two ends will attract, smashing the wire together, and that would be bad. TDU has cast coils in ice, sometimes with fibers to increase strength.

the only alternative switch i can think of is mechanical contact like TDU's 16KJ cap bank. sorry i can't get links to work.

good luck, be safe, and post results

ramses

Shaun

Wed Mar 12 2008, 10:18PM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

You are pretty much going to be forced to use an induction launcher, unless you plan on launching a massive projectile. However, you're right on with thick wire and low turns. That's what these big discharge caps are for.

6kJ will be quite a bang indoors and will remove limbs should you become part of the circuit. Ironically, the easiest way to switch these capacitors is some sort of spring-loaded mechanical contact switch.

What kind of charging power supply did you have in mind?

w1vlf

Thu Mar 13 2008, 12:31AM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

TDU???

Myke

Thu Mar 13 2008, 02:10AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Tesla Downunder

w1vlf

Thu Mar 13 2008, 11:23AM

Registered Member #1329 Joined: Mon Feb 18 2008, 07:31PM
Location: Harwinton Connecticut
Posts: 53

Thank you!! Sory ,,still new to this game

Travlax1

Thu Mar 13 2008, 06:48PM

Registered Member #1388 Joined: Wed Mar 12 2008, 04:42PM
Location:
Posts: 23

Ok, we're going in a slightly different direction now. The guy who's donating our capacitors actually has 4 4000V, 3000 Joule (375 uF) capacitors which we're going to take instead. So, with this is mind, should I go with them in series for high voltage or parallel for capacitance? Also, what would be the best wire to use and how many coils? Thanks

ramses

Thu Mar 13 2008, 07:39PM

Registered Member #1208 Joined: Thu Jan 03 2008, 05:30PM
Location: Chesterland, OH
Posts: 154

that depends. if induction, i would be inclined to go series parallel. TDU ( again, see the link), has had awesome results with all parallel, but most of the pulse will probably come after the projectile leaves the field. and how did you get someone to donate those beasts? i would suggest series MOTs to charge, you'd need 3-4 in series to charge to ~8kv.

play safe,
ramses

WaveRider

Thu Mar 13 2008, 09:32PM

Registered Member #29 Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500

If you want to design an induction launcher, smaller capacitance and higher voltages are desirable. This would favour a series combination of your capacitors.

Keep in mind that induction guns need 10-100 times the current and 0.1-0.01 times the firing current pulse widths to achieve good performance in comparison to reluctance guns. Mechanical switches would be the way to go, as well as careful attention to coil current/armature/capacitor voltage dynamics for optimal performance.

Also, special attention needs to be paid to mechanical design of the coil if you want to pass 10kA through it without self-destructing as a result of forces on the windings. Insulation capable of withstanding kV of interturn voltage will be needed too...

Techniques for induction guns have a lot in common with can crushers. TDU's can crushing experiments can yield some excellent tips for switching high current/high voltage.

If you choose to go the reluctance gun route, use armatures that reduce eddy currents....otherwise your results will likely be disappointing given the capacitor energy at your disposal...

Have fun and be safe!

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