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Can a fusor explode?

Posted: Sat Nov 12, 2005 2:12 am
by Steven Sesselmann
With the efficiencies achieved by the fusors in this group, it seems pretty
unlikely that any of them are going to light up the neighborhood, however
and for what it is worth, I put together a little thought experiment (see
attached pdf).
Any comments or references to more accurate analyses would be
appreciated.

Steven Sesselmann

Re: Can a fusor explode?

Posted: Sat Nov 12, 2005 9:42 am
by Frank Sanns
Yours is precisely the case for why I do not belive a runaway has ever happened for two reasons.

#1. Assume a super gain of 1:10 input:output. You put 1 watt in you get 10 watts out. Run the fusor at some high power like a killowatt. That is 10 KW out. That kind of power gain WILL NOT melt a hole in a fusor in a second or two. It takes quite a bit of energy to melt something that can conduct the heat to another cooler place very quickly like metal can. Unless you were already running the fusor red hot before fusion started, you will not melt it.

#2 If you calculate all the energy from all of the fuel in a fusor, you will find that if it ALL went at once, it would be the power of a quarter stick of dynamite if you have a large fusor. A medium large fire cracker if you have a smaller one. That is if ALL of the fuel goes in a millisecond.

Of course in both scenarios you would be dead from the neutrons and everything around you would be activated for quite some time but I think we have little cause for worry of the fabled Sasquatch runaway.

Frank S.

Re: Can a fusor explode?

Posted: Sat Nov 12, 2005 5:24 pm
by MARK-HARRISS
You mean the fabled "modulated octapole fusor" breakthrough?.

Re: Can a fusor explode?

Posted: Sat Nov 12, 2005 8:33 pm
by Frank Sanns
Good one Mark!!! I certainly deserved that one with my fables!

The irony of all this though is that I did have a recent breakthrough (not a runaway) but I now fear nobody on the board will believe me when I do make it public here. Guess that is what happens when you cry wolf. Keep tuned though. Something interesting is coming as some of you have already heard direct.

Frank S.

Re: Can a fusor explode?

Posted: Sat Nov 12, 2005 11:58 pm
by Steven Sesselmann
Frank, try me, I might believe you...

Steven Sesselmann

Re: Can a fusor explode?

Posted: Sun Nov 13, 2005 3:24 am
by MARK-HARRISS
Well Frank, I think you're one of the many here whose integrity is readily apparent.

I look forward to ANY new results.

Re: Can a fusor explode?

Posted: Sun Nov 13, 2005 3:55 am
by Alex Aitken
Assuming the temperature would rise in the fusor is flawwed without additional confinement. Ions exceeding the energy of the well would just embed themselves in the wall.

Re: Can a fusor explode?

Posted: Sun Nov 13, 2005 10:31 am
by Frank Sanns
Mark and Seteven,

Thanks for the vote of confidence. I can not really share the particular detail until the legal stuff is investigated but I can say that it is NOT over unity but neutrons are produced and this first step paves the way for some novel changes. This approach is not just talk. It has now been tested, evaluated, and proven. I hope to have more details on here in about a month. There is also the outside chance that somebody somewhere has already covered this but I have not uncovered it yet. If it has been done, it certainly has not been exploited to its full extent.

Frank S.

Re: Can a fusor explode?

Posted: Sun Nov 13, 2005 10:40 am
by Frank Sanns
Kinetic Energy = 1/2 mv^2 = Joules

Joules = heat

Ions, neutrons, electrons, protons, photons and the like, when they stop are heat. The neutrons and short wavelength photons(like x-rays/gamma rays) will escape and not deposit thier energy in the fusor shell but all of the other plasma species like ions, electrons and longer wave photons (like IR, visible and UV light) and neutrals will be the species that supply the heat to the shell.

Frank S.

Re: Can a fusor explode?

Posted: Sun Nov 13, 2005 12:30 pm
by Alex Aitken
I honestly have no idea if you are agreeing with me or not Frank.

My point is that the idea is based on the concept of thermal avalanche. The reaction produces heat, heat makes the reaction go faster which increases the temperature and you are into a vicious spiral. But since the ion temperature is nothing more than the energy given by the potential gradient, it cannot increase. A 'temperature increase' caused by an unusual number of fusions would cause the fragments to escape the well and embed themselves or lose energy to the steel container. So additional fusion does not heat the plasma, its bootstrapped to the grid voltage.

Re: Can a fusor explode?

Posted: Sun Nov 13, 2005 3:53 pm
by Steven Sesselmann
Frank, I can't wait to hear more about your invention, because I am in the
same situation as you, and can't talk.

I hope both ideas are different and that they both work.

Mine still has to be built.

Steven

Re: Can a fusor explode?

Posted: Mon Nov 14, 2005 10:21 am
by Richard Hull
I'll have to go along with Marvin on this last idea of temperature of the plasma increasing. This is ostensibly not a thermal machine. It is not designed as one and, thus, it will not benefit from plasma heating as there is no confinement of the active heated plasma. As such, it all goes to the shell and is a complete loss mechanism. We fuse solely at the instant of collision, (pretty much near the center), we can't heat the gas in the entire vessel to fusion temps in a fusor. We might hope for boosting the efficiency of the central reaction by some artifice, but that is about it.

The fusor will destroy itself only when you put enough outside energy into it to do so. It will not dismantle itself due to any fusion process within. Long before you get decent fusion, you will feed in enough energy to heat the grid, insulator or a glass port to some failure mode unfriendly to the continuation of fusion, solely due to the input energy being converted to waste heat by particle bombardment.

The calcs are not wrong it is just the physical world will not let you get there from here. You will not tie down nature's safety valve placed on fusion.

Richard Hull

Re: Can a fusor explode?

Posted: Mon Nov 14, 2005 3:39 pm
by Steven Sesselmann
Richard, yes, using Deuterium, it should be pretty unlikely to see a
cascade reaction, however I would want to do my calculations more
carefully if introducing Boron11 or Lithium6 or something like that.

Every now and then you should do a stocktake of the membership in this
group :)

Steven

Re: Can a fusor explode?

Posted: Mon Nov 14, 2005 5:46 pm
by Frank Sanns
Marvin and Richard,

Your descriptions are great for option #1 of my post. More energy in equals proportionally more energy out.

For option #2 this does not and can not hold. The mechanism is not what we think for conventional hot fusion. It is not because we never come anywhere near the density to sustain fusion. If there were a runaway or if for some reason fusion would occur by another mechanism as it might in sonofusion or cold fusion or in Bose Einstein Condensates, then the criteria in which you refer will not be true in the least. If a fusor goes bang or even poof, then something else besides conventional hot plasma physics is going on in there.

My post addresses both of these scenarios so Marvin, I was not disagreeing with you but I was not totally agreeing with you either.

Frank S.

Re: Can a fusor explode?

Posted: Tue Nov 15, 2005 11:48 am
by Richard Hull
Any such "other" method would be interesting to see or hear about in an active experimental sense.

As for Steve's B-11 and Lithium 6 ideas with deuterium....Well, so far, no one has presented physical proof of that pudding in a fusor. I wonder when reactions with B-11 will die the natural death they deserve until someone puts a foot in the path and burns th' stuff, supplying proof of all the hypothetical machinations and as yet unbaked thermonuclear puddings.

Everyone who posits or rehangs the B-11 reaction thinks they can get the ultra-expensive, enriched and lethal B-11 in the chamber in some convenient fashion. The doing here is quite a task. Even less expensive, un-enriched natural B product presents the same lethal possibilities and nightmares. (if un-enriched 20% of your boron banging is waste heat.) Of course, if you survive the introduction of B-11 enriched Diborane and BF3 exhausting from the pump system, then there is always the backing pump body damage, itself, and the oil pickup of same.

All could be overcome with money time and a bit of sweat, of course. The government sponsored boys haven't even dabbled in this "wonder fuel" yet. Ever wonder why?

Richard Hull

Re: Can a fusor explode?

Posted: Tue Nov 15, 2005 4:18 pm
by Steven Sesselmann
Point taken Richard, theory and practice are not the same.

In any case I don't think exotic fuels will be needed, the D+D reaction will
burn by itself, given the right conditions.

Steven

Re: Can a fusor explode?

Posted: Wed Nov 16, 2005 3:47 am
by DaveC
It has always seemed most plausible to me that the so-called "runaway" episodes are really nothing more than thermally enhanced emission from the negative inner grid.

For the grids made of low melting temp wire, there is practically no chance whatever of a runaway event ocurring, since their melting temperatures are far, far below good thermionic emission temperatures.

Everyone noodling about runaways... ought to doodle with the Richardson Dushman equation using real numbers for the work functions of his particular grid material. The results will be eye opening for most people. You need, Tungsten, or Tantalum operating at about 2500K or higher, to get any significant electron emission. If you use thoriated tungsten wire, you can drop the emission temps by upwards of 1000K and see significant output in the 1400K range.

It seems to me, that if one operates with enough current to heat the grids till they approach the thermionic emission temperature, the assuming the Voltage is high enough to overcome the Space Charge Current limitations of the Child-Langmuir Eqn, then one could get an ever-increasing current and with it ever-increasing (but not Nuclear runaway) Neutron emission, as the grid emits more and more electrons, thus causing the Deuteron density to also increase.

Such a device will run up in current until the Power Supply Voltage drops and shuts things down. If you have a beast of an HV supply, then you could expect to see meltdown.. of the grids, and possibly a hole burned through the fusor shell. A few KW is likely to be enough to do it.

Dave Cooper

Re: Can a fusor explode?

Posted: Wed Nov 16, 2005 1:20 pm
by Richard Hull
Dave hit the nail on the head. In most usable supplies, there is current limiting of some sort. In mine, I just have a 30k ohm 200 watt resistor in oil. So, in my system, thermal runaway so increases the desire for current that the voltage nose dives as the limter resistor voltage rises. Thus, I see a reduction of fusion at thermal emission runaway as I slide off the cross sectional curve. Beefy supplies or constant voltage supplies set to very high current limit values, as Dave notes, would see an increase in fusion up to where the supply faults out or you melt something inside the fusor.

These are all practical, real world issues that any real fusor operator sees at every operation session and guards against.

Richard Hull