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Long pulse DRSSTC pictures

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Steve Ward

Sun May 21 2006, 06:53PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

I always liked the look of the old SSTC sparks, how they are so thick and gnarled. So to achieve that effect with a DRSSTC, ive run it in single shot mode, and 5-8mS pulses. The primary current peaks to 900A+ after about .75mS, then decays to around 150A for the last 3-5mS where it stays relatively constant. With careful tuning, i managed to make the primary current *decrease* with ground strikes. Without careful tuning, the primary current will *increase* with ground strikes, and hold over 1000A for many mS!! The DC filter caps are charged to about 220VDC, and are left with about 60VDC when a single shot is over... that means 245J is used up in a single bang!! The target is set to 36", but a few of the sparks reached out to 40" and one even hit a controller on my shelf at 48". Im already thinking about how to get even bigger sparks

. I find it particularly interesting that so many branches are formed on a single shot (all pictures are single shots).

Pictures are posted here:

http://www.stevehv.4hv.org/DRlongpulse/

Enjoy!

Marko

Sun May 21 2006, 07:10PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Wow, I also like The Hot arcs

I must admit it doesn' look mighty like 100% CW bit it's still absolutely awesome.
Great work!

Steve Ward

Sun May 21 2006, 07:17PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

I still want a 10kW CW system

.

I guess i will just keep going till something blows up, then back off a little (normal proceedure). Though, i think a coil like this could really benefit from a higher Z tank circuit. Im considering building a whole new DRSSTC specifically for this type of operation.

...

Sun May 21 2006, 07:31PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Wow, very impresisve!

Kind of hard to imagine that the energy used for that streamer is the same as a a 1g projectile going at like mach 2

HV Enthusiast

Sun May 21 2006, 08:34PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

wrote ...

The DC filter caps are charged to about 220VDC, and are left with about 60VDC when a single shot is over... that means 245J is used up in a single bang!! The target is set to 36", but a few of the sparks reached out to 40" and one even hit a controller on my shelf at 48". Im already thinking about how to get even bigger sparks

Nice work Steve - cool photos. Looks like you just accidentally stumbled on one of the biggest challenges with solid state radar systems these days, the elusive long pulse. Anyways, the challenge of course is to maintain voltage across the entire pulse to deliver constant energy through the entire pulse.

I propose the next part of your experimentation would be to achieve the long pulse, but with maintaining constant voltage across the entire pulse with constant meaning a few voltage drop maximum at the bridge rails. I'd be curious to see how that compares with what you are doing now.

To do this, you could simply make a discrete linear regulator (read that as new COOL project!) and use a fairly large capacitor bank (size you can determine with simulation) to drive it. Say charge the capacitor bank to maybe 400V or whatever it takes to maintain headroom on the regulator across the entire pulse, and regulate at 220V at the input to your bridge. With enough bandwidth, this should work quite well. Sure, it will be pretty inefficient, but for a single non-repetivie pulse, should be fine for experimentation.

BTW, i really hope you weren't doing this on your 21st Birthday weekend . . . You should be out drinking your brains out and letting loose . . .

Or at least spending all day sunday in bed with a massive hangover !

Dan

Terry Fritz

Sun May 21 2006, 11:58PM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

VERY cool! Steve!!

I see the corkscrew effect shows up very well here. Almost unimaginable single shot power!!!

Much to ponder....

BTW, i really hope you weren't doing this on your 21st Birthday weekend . . . You should be out drinking your brains out and letting loose . . . Or at least spending all day sunday in bed with a massive hangover !

I did that... Your better off staying home

You can always turn into a rock star like Steve C. latter

I spent all weekend working on MOT charging systems...

Cheers,

Terry

HV Enthusiast

Mon May 22 2006, 01:01AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

I wonder if both of the following would exhibit the same cork screw behaviour.

1. Approaching CW (low PRF, long pulsewidth)
2. Approaching CW (very high PRF, short pulsewidth)

In either case, the system is approaching CW mode of operation, but short vs. long pulsewidth. Could be another interesting experiment.

Part Scavenger

Mon May 22 2006, 02:47AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Geez, don't encourage him to waste brain cells. If he's got extra, please send them to me! Your's are top quality Steve!

That's pretty cool stuff with the hot arcs! Love the pics.

Tesladownunder

Mon May 22 2006, 04:34PM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Impressive at 245j/bang. This is what 2500J/bang is like

(with the little help of a very thin wire to start things off..)

Peter

1148315654 10 FT9914 Pulsecapexplodingwire35g2kjnoinductor

coaster_chris

Mon May 22 2006, 05:48PM

Registered Member #359 Joined: Sat Apr 01 2006, 09:27AM
Location: Utrecht, The Netherlands
Posts: 16

@TDU
*SIGH* You and your big caps....

Steve, that are for shure some realy impressive streamers! What a length for a DRSSTC! Well done m8!

Chris

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