Proton-boron Success! - Nope!
- Dennis P Brown
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Re: Proton-boron Success! - Nope!
The best approach to getting an approximate check on a VdG's voltage is to use a second sphere (should not be too small but does not need to be similar in size, either.) Ground this second sphere, run the VdG and slowly move the second sphere closer to the VdG. This must be done in very dry air, of course. When the air breaks down and the arc jumps, measure the distance in centimeters. This gives a rough measure of the voltage.
How did you measure the proton current? I'd like to know since that would be useful once (or if?) I ever get mine working ... .
Also, how did you measure your Van de Graaff current?
How did you measure the proton current? I'd like to know since that would be useful once (or if?) I ever get mine working ... .
Also, how did you measure your Van de Graaff current?
- Richard Hull
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Re: Proton-boron Success! - Nope!
The arc method is fine provided, and only if, it is done under full load with the VDG hooked to a working accelerator that is in full load operation. Just jumping an arc in air with the generator just sitting there in an unconnected condition, tells you nothing related to its voltage output in an "in use situation" hooked to a load.
The two are vastly different. Depending on the load and the VDG, Most VDGs will not produce even 5% of their no load, arc measured, voltage when loaded in an accelerator application.
VDG's or any static machine, for that matter are some of the highest internal impedance HV power sources known to man and can not supply much vlotage, current or power at all to a load.
Richard Hull
The two are vastly different. Depending on the load and the VDG, Most VDGs will not produce even 5% of their no load, arc measured, voltage when loaded in an accelerator application.
VDG's or any static machine, for that matter are some of the highest internal impedance HV power sources known to man and can not supply much vlotage, current or power at all to a load.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
- Jason C Wells
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Re: Proton-boron Success! - Nope!
You can easily measure the current that the drive belt can deliver to the VDG terminal. You can easily measure the dead short current that the VDG terminal can provide to ground. These things don't tell you what's going on during nominal operation though. They do tell you order of magnitude sort of information. I use them for the purpose of determining if what I am seeing makes any sense.
Proton current at the ion source can be deduced from the current supplied to the ion source assuming equilibrium and charge conservation, perhaps a bad assumption since we don't know where the charge leaks are. My ion source is akin to a Penning trap. I measure the current supplied from a 5000v potential across one stage of a small ladder multiplier. When pressure is low my penning source will draw about 50 microamps. My ion source should be able to deliver a maximum of 50 microamps of protons assuming perfect efficiency. The glow out of the penning source at this pressure is barely perceptible even after becoming accustomed to the darkness in my garage.
Proton current at the target end of things is as simple as putting a meter between the target and ground, except it isn't. I measured 10 microamps at this end, but that includes ejected secondary electrons travelling opposite direction back up the accelerator column. Just about the time I was getting some target bias set up, I fried my ammeter. I also don't know how many protons get stuck on the inside wall of the glass due to poor beam collimation. If I ballpark the beam current to be something less than 10 microamps, say 1 microamps, then my entire beam line is about 2% efficient. But all of this is a swag.
I just got a new ammeter tonight. (Actually I bought three. Two to use and one for a spare.) This $15 dollar student desktop meter has proven surprisingly robust. It only failed when I applied 400 VDC through it to ground due to fat fingers.
I don't know if that helps you Dennis. A sparky has a better intuition than I do for these sorts of things. Feel free to ignore dumb things that I wrote. You are probably right and I am probably wrong.
Regards,
Jason C. Wells
Proton current at the ion source can be deduced from the current supplied to the ion source assuming equilibrium and charge conservation, perhaps a bad assumption since we don't know where the charge leaks are. My ion source is akin to a Penning trap. I measure the current supplied from a 5000v potential across one stage of a small ladder multiplier. When pressure is low my penning source will draw about 50 microamps. My ion source should be able to deliver a maximum of 50 microamps of protons assuming perfect efficiency. The glow out of the penning source at this pressure is barely perceptible even after becoming accustomed to the darkness in my garage.
Proton current at the target end of things is as simple as putting a meter between the target and ground, except it isn't. I measured 10 microamps at this end, but that includes ejected secondary electrons travelling opposite direction back up the accelerator column. Just about the time I was getting some target bias set up, I fried my ammeter. I also don't know how many protons get stuck on the inside wall of the glass due to poor beam collimation. If I ballpark the beam current to be something less than 10 microamps, say 1 microamps, then my entire beam line is about 2% efficient. But all of this is a swag.
I just got a new ammeter tonight. (Actually I bought three. Two to use and one for a spare.) This $15 dollar student desktop meter has proven surprisingly robust. It only failed when I applied 400 VDC through it to ground due to fat fingers.
I don't know if that helps you Dennis. A sparky has a better intuition than I do for these sorts of things. Feel free to ignore dumb things that I wrote. You are probably right and I am probably wrong.
Regards,
Jason C. Wells
- Dennis P Brown
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Re: Proton-boron Success! - Nope!
Thanks for the description and details; 1 microamp sounds reasonable for a current on an operational accelerator and measuring the current directly at the target is a good method but, as you correctly point out, secondary electrons will cloud the results. I think you are doing good work and any accelerator project - especially one that uses a Van de Graaff - is a battle to fix issues to achieve sufficient voltage potential; I know only too well about those issues. I still feel you need to get rid of the wood box and use Plexiglas around your VdG - at least replace the wood section that the accelerator tube pass's thru with plexiglass. Wood, with its high water content is a very good conductor (at VdG voltages) and will hurt the systems ability to achieve full potential.
- Jason C Wells
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Re: Proton-boron Success! - Nope!
I've been thinking about ditching the wood box prior to your most recent post, but I've got everything "installed" right now and other things are causing me trouble. Also, the wet season in Seattle is upon me. So I might need me environmental chamber anyway. Right about the time I get everything else sorted out, humidity will be back causing me trouble.
Regards,
jason
Regards,
jason
- Jason C Wells
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Re: Proton-boron Success! - Nope!
I missed a comment by Steve Sesselman. Steve, I describe my apparatus as proton-boron fusion in a linear accelerator, PBFLA for short. I haven't posted any documents yet. My equipment is: a 600kV Van De Graaff, a modified penning trap to ionize hydrogen, a Hofmann apparatus, a custom glass accelerator column, a diff pump, rough pump, a 400V battery, a Cockroft-Walton ladder multiplier, and assorted plumbing bits and pieces. A crude and obsolete schematic is attached. It should be sufficient to get the main idea across.
Regards,
Jason
Regards,
Jason
- Steven Sesselmann
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Re: Proton-boron Success! - Nope!
Jason, thanks for the schematic, so if I understood this correctly the VDG is inside the vacuum chamber, very neat idea, I hope you get results.Jason C Wells wrote:I missed a comment by Steve Sesselman. Steve, I describe my apparatus as proton-boron fusion in a linear accelerator, PBFLA for short. I haven't posted any documents yet. My equipment is: a 600kV Van De Graaff, a modified penning trap to ionize hydrogen, a Hofmann apparatus, a custom glass accelerator column, a diff pump, rough pump, a 400V battery, a Cockroft-Walton ladder multiplier, and assorted plumbing bits and pieces. A crude and obsolete schematic is attached. It should be sufficient to get the main idea across.
I prefer negative acceleration into a negative target but so far I only have theoretical evidence of this being a better approach.
Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
- Jason C Wells
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Re: Proton-boron Success! - Nope!
The box around the VDG is just for humidity control and is at atmospheric pressure. The interior of the sphere is also at atmospheric pressure. I can see from the schematic how it can be confusing. (Sorry for the late reply. I've been away from my project for a time.)
Regards,
Jason C. Wells
Regards,
Jason C. Wells
- Dennis P Brown
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Re: Proton-boron Success! - Nope!
Again, I strongly suggest you get rid of the wood box; it will draw current from the machine. Use a plexi-glass box. Thin sheets aren't that expensive. At least at the exit port of the accelerator tube. There the wood will really act as a conductor!
I am, as you may note from my posts trying both a very large VdG and building a rather massive voltage multiplier for my deuteron accelerator. Best of luck with your system. Keep up the work - it takes time but is worth it - do avoid exploding caps as I just failed to do (lol.).
I am, as you may note from my posts trying both a very large VdG and building a rather massive voltage multiplier for my deuteron accelerator. Best of luck with your system. Keep up the work - it takes time but is worth it - do avoid exploding caps as I just failed to do (lol.).
- Jason C Wells
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Re: Proton-boron Success! - Nope!
The box will be deleted during my next foray into my project. I was able to observe a sporadic large umbrella shaped plasma that terminated on the plywood box. This confirms your claim that the box is a problem.
I am also planning on incorporating a ladder multiplier. VDGs are too finicky in my opinion.
I am also planning on incorporating a ladder multiplier. VDGs are too finicky in my opinion.
- Dennis P Brown
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Re: Proton-boron Success! - Nope!
LOL on the VdG issues! Know only too well and why I am attacking that issue a number of ways: a very large VdG (posted) and two approaches to a high voltage multiplier (VM; one system I have posted images the other still in the works and will be posting some aspects.)
A few words of advice on the VM: use a high frequency supply if possible; 60 Hz isn't easy to do (but the diodes sure are cheap.) While I have achieved over 40 kV using a NST (7.5 kV) and intend to top out a good bit higher, that system is rather large - certainly inexpensive but very large and will require oil. Lots of stages is not the best approach; of course, with a high freq. power supply one can get away with more stages. Also, flybacks require high freq. to drive them. They can give you both more voltage and power for the buck.
Best of luck and really look forward to your progress and results!
A few words of advice on the VM: use a high frequency supply if possible; 60 Hz isn't easy to do (but the diodes sure are cheap.) While I have achieved over 40 kV using a NST (7.5 kV) and intend to top out a good bit higher, that system is rather large - certainly inexpensive but very large and will require oil. Lots of stages is not the best approach; of course, with a high freq. power supply one can get away with more stages. Also, flybacks require high freq. to drive them. They can give you both more voltage and power for the buck.
Best of luck and really look forward to your progress and results!