Capacitor bank trigger challenge

[Rezwan]

One of the challenges of the dpf seems to be getting the charges from the capacitor banks synchronized to within nanoseconds. This is an engineering challenge, and its solution will have an impact on the ability of the dpf to coordinate the charge that is to lead to net energy.

I am having a hard time wrapping my head around this issue. Would love to hear from people working on the dpf or on other devices with capacitor banks to clarify this issue.

Just spoke with a friend of mine in —- well I’ll let him out himself — who is part of a lab using a dpf in research. He asked if our dpf works well, and I said they are still working on consistency, and optimizing the 12 capacitors – to get them triggered at the same time.

He: I have heard before that having so many capacitors, maybe triggering them at the same time is a real challenge.
Me: How is your pf set up?
He: Our pf has a 16 KVolt capacitor with a spark gap which helps firing. Our PF is 4.5 K joul.
Me: A single capacitor? Not a bank?
He: No not a bank.

Me: Have you heard of Lee Sing in Singapore?
He: Yeah. Prof Lee is someone who has a very simple model which shows how an PF works. Prof Lee has a powerful team.
Me: I heard it was some kind of base model that he’s helped popularize so people in developing countries could work with the pf – he promotes the pf & pf research.
He: Yeah that’s right, our PF was developed under his model.

So – apparently lots of pf’s out there have minimal capacitors. I did not know that. Time to gear this site and the forums up to explore every facet. Like the good old days when everyone had their own steam engine model, with varying levels of effectiveness.

And time to connect the dots of the dpf research community.

[Aeronaut]

Rezwan wrote: One of the challenges of the dpf seems to be getting the charges from the capacitor banks synchronized to within nanoseconds. This is an engineering challenge, and its solution will have an impact on the ability of the dpf to coordinate the charge that is to lead to net energy.

I am having a hard time wrapping my head around this issue. Would love to hear from people working on the dpf or on other devices with capacitor banks to clarify this issue.

Just spoke with a friend of mine in —- well I’ll let him out himself — who is part of a lab using a dpf in research. He asked if our dpf works well, and I said they are still working on consistency, and optimizing the 12 capacitors – to get them triggered at the same time.

He: I have heard before that having so many capacitors, maybe triggering them at the same time is a real challenge.
Me: How is your pf set up?
He: Our Of has a 16 KVolt capacitor with a spark gap which helps firing. Our PF is 4.5 K joul.
Me: A single capacitor? Not a bank?
He: No not a bank.

Me: Have you heard of Lee Sing in Singapore?
He: Yeah. Prof Lee is someone who has a very simple model which shows how an PF works. Prof Lee has a powerful team.
Me: I heard it was some kind of base model that he’s helped popularize so people in developing countries could work with the pf – he promotes the pf & pf research.
He: Yeah that’s right, our PF was developed under his model.

So – apparently lots of pf’s out there have minimal capacitors. I did not know that. Time to gear this site and the forums up to explore every facet. Like the good old days when everyone had their own steam engine model, with varying levels of effectiveness.

And time to connect the dots of the dpf research community.

Separating the grounds was a great starting point. So many electrical problems trace back to a floating ground, unexpected current in the ground, electrical noise on the ground, etc. Sometimes just pouring some water on the ground stake solves a problem…

Assuming that the entire grounding system checks out, I have to verify that all 12 leads are the same length, and that all 12 caps have essentially the same voltage and discharge times. The lower the voltage, the more critical it is to know precisely how much each cap is contributing (or not) during the microsecond or so of planned discharge.

Moving the trigger box directly above the anode should give a stronger IR trigger signal while permitting shorter wires to the switches. Since the switches work with a spark gap, shorter wires should also give the trigger to switch signal more kick.

Hope this helps.

[JimmyT]

I’m sure that it has not escaped your notice that this is the exact same problem that the Manhattan project faced when building their first plutonium weapon. (And all plutonium weapons built since then). The currents involved were a bit less, but the problem was exactly the same. How to send multiple electrical impulses to hexagons surrounding a sphere of plutonium.
And have them all arrive at exactly the same time.

Same thing with the Z-machine and all the inertial confinement machines which use lasers from multiple directions to crush a lithium deuterium pellet. All rely on precisely timed electrical pulses from multiple capacitors.

So this problem is not unique to this project, or even unique to DPF projects.

I’m sure that Mr Lerner is garnering what knowlege he can from these other projects.

[mchargue]

NASA always has good papers on all kinds of stuff. Here’s one on synchronization of capacitor banks in discharge,
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650013566_1965013566.pdf

Something on the switching system used to make it all go *pop*,
http://en.wikipedia.org/wiki/Ignitron

And, as always, there’s the garage-guys’ DIY approach,
http://www.powerlabs.org/capexperiments.htm

Post some specs on what you’re trying to do, please. I’d love to look it over.

Pat

[JimmyT]

I certainly don’t have the specs. But you can see the hardware in the picture gallerys from focus fusion’s homepage. The wiring is displayed pretty plainly.

[Aeronaut]

Thanx for the docs, mchargue. I’m sure the component values are at least in the ball park with FF.

[Rezwan]

Eric says the dpf used in the Texas A&M;experiments had multiple capacitors. How many capacitors? Hard to tell from the cropped picture.

Attached files

[Focus Fusion Society]

JimmyT wrote: I’m sure that Mr Lerner is garnering what knowlege he can from these other projects.

Yes, and the capacitor bank was designed with all that in mind. Still, the reality is these capacitors are not quite behaving according to design so there’s a fly in the ointment somewhere that is being systematically sleuthed out.

[belbear]

Admin wrote:

I’m sure that Mr Lerner is garnering what knowlege he can from these other projects.

Yes, and the capacitor bank was designed with all that in mind. Still, the reality is these capacitors are not quite behaving according to design so there’s a fly in the ointment somewhere that is being systematically sleuthed out.

Are all the wires leading from the trigger box to the switches exactly the same length? i.o.w. as long as the longest one needs to be.
Even light speed is not sooo fast when it comes to nanosecond precision….

[Henning]

belbear wrote:
Are all the wires leading from the trigger box to the switches exactly the same length? i.o.w. as long as the longest one needs to be.
Even light speed is not sooo fast when it comes to nanosecond precision….

Maybe a good idea for leveling out the last few ns to have wires of different length. It’s about 30cm per ns, see http://www.wolframalpha.com/input?i=lightspeed+*+ns (the forum software swallows the star, you have to fill it in yourself).

But then you’re adding additional inductance, and I somewhat doubt it’s a problem of the wires from the capacitors and more one within the triggering system.

[mchargue]

What kind of switch system are you using to connect the capacitors to the FF reactor? (Ignitron, spark gap, etc.)

Given that a switch is ‘triggered’ on, how much repeatability is there with any one switch w.r.t. the trigger? That is to say, what’s the jitter between receipt of the triggering event, and the switch closure.

You may be able to control/limit jitter by constraining the environment of the switches. (common temperature, pressure, humidity, etc.)

If it’s a synchronization issue among many such switches, what means are you using to turn the switch on? If the switch trigger is electronic in nature, there are certainly options available to dynamically tune the trigger to get the desired switch behavior based on feedback from the switches & environment.

Sounds like a fun engineering problem. I’d love to hear more about it.

Patrick

[Brian H]

mchargue wrote: What kind of switch system are you using to connect the capacitors to the FF reactor? (Ignitron, spark gap, etc.)

Given that a switch is ‘triggered’ on, how much repeatability is there with any one switch w.r.t. the trigger? That is to say, what’s the jitter between receipt of the triggering event, and the switch closure.

You may be able to control/limit jitter by constraining the environment of the switches. (common temperature, pressure, humidity, etc.)

If it’s a synchronization issue among many such switches, what means are you using to turn the switch on? If the switch trigger is electronic in nature, there are certainly options available to dynamically tune the trigger to get the desired switch behavior based on feedback from the switches & environment.

Sounds like a fun engineering problem. I’d love to hear more about it.

Patrick

AFAIK, they’re diamond switches. https://focusfusion.pmhclients.com/index.php/site/article/lpp_team_starts_looking_at_ion_beam_energy_extraction/

But I’m not sure if the switches between coil and capacitors are the same ones or identical to those used to fire up the cathodes!

[JimmyT]

They were going to use diamond switches, but it turns out that diamond switches that big had never been made before. Probably could be, but never had been. Plus this would be introducing yet another unknown, untested variable into the mix. So Eric opted for an off the shelf comercially available switch instead. Not sure of the type used though.

Rather like the ones on the wall I gather. Up is on, down is off. he, he. Did you know that the opposite convention is used for wall switches in Europe?

[Brian H]

JimmyT wrote: They were going to use diamond switches, but it turns out that diamond switches that big had never been made before. Probably could be, but never had been. Plus this would be introducing yet another unknown, untested variable into the mix. So Eric opted for an off the shelf comercially available switch instead. Not sure of the type used though.

Rather like the ones on the wall I gather. Up is on, down is off. he, he. Did you know that the opposite convention is used for wall switches in Europe?

That’s because they’re lazy and want it to be easier to turn the lights on. :cheese:

Some people say “open the light” and “close the light”. But of course, an open switch is off, and closed is on. They never appreciate it when I explain their language is electrically illiterate … :-S

[Dr_Barnowl]

Brian H wrote: Some people say “open the light” and “close the light”.

I think that probably stems from the lights being a shuttered lamp, so more historical precedent than electrical ignorance.

I always had trouble with open / closed for circuits when I was young. Something inside equated “open” with “open lets things through”. I thought it was intuitively backwards and I think only persistent reinforcement has instilled the opposite terminology.

You open valves, doors, shutters, windows, gates, etc. to let things through. Only in a circuit do you close something to let the electrons through. Counter-intuitive.

Back on the subject of capacitor banks, what kind of voltage / energy is required? Would 194MJ at ~ 4500V be enough, or is the high voltage more important? I’m thinking of EEStor cells ; OK, they’re currently even less tangible than a net-gain tokamak … but would they be useful if they could be bought?

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