Theoretical (imaginary?) output of a fusor

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
Dan Ullfig
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Theoretical (imaginary?) output of a fusor

Post by Dan Ullfig » Thu Jul 18, 2019 2:07 am

So I was wondering. If we were to daydream that a small fusor was, say, 80% efficient, in other words most of the protons and boron going in fused sorta immediately into helium, how much energy would this thing put out?

Yes, I know there's tons of "what ifs" and variables in my question, I'm just wondering, could a fusor power a car for example?

Dan

Ps.: it's daydreaming. Make whatever assumption necessary.

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Richard Hull
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Re: Theoretical (imaginary?) output of a fusor

Post by Richard Hull » Thu Jul 18, 2019 3:51 am

In short, ...No....An 80% efficient fusor could not power a car. The reason is all those "what ifs" and a whole bunch of gotchas are there even if you wish to discount them in theory.

Why??

Those very "what ifs" and gotchas that you don't seem to care about would have to be dealt with 100% successfully in a real world finished product or the car would not move. It would just have an 80% efficient fusor sitting in it.

Finally a small thing you didn't include.......80% at what input energy to use that 80%.... Little details like this tells us you haven't a clue about the energy required to actually accelerate the mass of a functional car and keep it moving at highway speeds. Remember the mass of the car would have to include a massive battery bank that would be quite heavy.

A pie-in-the-sky question based on no real details related to 80% of what input energy

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

ian_krase
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Re: Theoretical (imaginary?) output of a fusor

Post by ian_krase » Thu Jul 18, 2019 9:02 am

I would be more worried about radiation than batteries. Even an aneutronic fusion reactor is (probably) going to make a mess of bremstrahlung.

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Richard Hull
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Re: Theoretical (imaginary?) output of a fusor

Post by Richard Hull » Thu Jul 18, 2019 5:43 pm

I was going to mention radiation from the fusor. But the poster wanted such simple overarching worries not to be considered.

I was going for the energy he expected to get the car up to functional speeds. ( not supplied)....I let all the very gory details, and the massive engineering effort fall be the wayside, as he asked. I figured getting a fusor up to 80% efficiency was a given in his posited scenario.

Kind of a silly original post from about 1573 different touchy angles willing to be left untouched upon.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Dennis P Brown
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Re: Theoretical (imaginary?) output of a fusor

Post by Dennis P Brown » Thu Jul 18, 2019 11:36 pm

Just a little more - first off, fusors are based on deuterium, not boron. If one uses boron, one certainly is not doing fusion via tunneling or what a fusor really does. Next, 80% of what? How many nuclei are they trying to propose being fused? The typical fusor pressure of 5 micron consisting of boron & hydrogen gas? They can easily do that calculation in a very simple manner assuming they research a few details that are on-line for anyone with a computer: that they haven't done this tells me they are either too lazy or that it is beyond their ability. In either case, spoon feeding does not enable learning; something I believe we promote here. So for the later case, take this as your homework, work out the details and present that result here for comment. We will check for errors (if any) and then aid you if there are issues. If the former, I am not here nor do I believe most people who are serious fusor posters here want to waste their/everyone's time answering non-fusor related questions that with moderate effort, one can workout for themselves.

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Mark Rowley
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Re: Theoretical (imaginary?) output of a fusor

Post by Mark Rowley » Fri Jul 19, 2019 2:56 am

"The typical fusor pressure of 5 micron"

Dennis, I think we need to get away from this old standard as the 2.75" cross Fusors and their comparatively higher pressures are becoming the norm. Same for the voltages as well. 15-25kv at less than 5ma and 15-30 mTorr is really the modern day average.

Mark Rowley

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Dennis P Brown
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Re: Theoretical (imaginary?) output of a fusor

Post by Dennis P Brown » Fri Jul 19, 2019 4:48 pm

Your preaching to a convert - lol. :)

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Frank Sanns
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Re: Theoretical (imaginary?) output of a fusor

Post by Frank Sanns » Fri Jul 19, 2019 8:34 pm

Being partly an instructional site, I will elaborate a little.

Each fusion of a proton and boron-11 will produce 1.4 x 10^-12 joules. Doing 1 fusion per second will give 0.0000000000014 watts.

To get just 1 watt of output, there needs to be 7.14 x 10^11 actual fusions.

Using the fundamental charge of 1.60 x 10^-19 coulombs per proton, that means around 0.114 micro amps of proton current.

At 1 volt potential that means that 10 million times more energy comes out than is put in.

There are two fundamental problems with this.

1. The fusion cross section of the reaction does not occur at 1 volt. Zero fusions will occur there. To get up to a voltage where the fusion cross section gives any hope of fusion, voltages of 500 KV are required.
Assuming every single proton boron interaction is productive (not even close, see #2) then the input energy goes up to 0.06 input watts needed for 1 watt output. That is 17 times the output for the input watts. Things are not looking so good.

2. Fusion is a statistically lossy process. VERY VERY few collisions will result in a fusion. You only have 17 times the energy to work with but the losses are in the quadrillions or higher. This is not even accounting for losses in the device itself or ionizing the protons.

In the end your 1 watt will take 1,000,000,000,000,000........ input watts of energy.

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Re: Theoretical (imaginary?) output of a fusor

Post by ian_krase » Sat Jul 20, 2019 4:48 am

This certainly explains why the big efforts have focused on thermalizing and then containing the ions so you can recycle the accelerating energy as heat -- or for that matter Doug Coulter's project where he apparently is trapping them in a non-thermalized way somehow so that they can be adiabatically reaccelerated for free. Unfortunately there are endless sources of losses.

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Dennis P Brown
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Re: Theoretical (imaginary?) output of a fusor

Post by Dennis P Brown » Sat Jul 20, 2019 9:47 pm

I think some people confuse fusors with the "big science" machines that use brute force to overcome the Coulomb barrier. These two types of devices use very different methods to obtain energy from fusion. To be clear for those not aware, collisions are not the method by which fusion occurs in a fusor - fusion can and does occur with no direct 'collision" in reality (the energies are just too low.) Rather, fusion occurs via tunneling in fusors. Since there is no known method to change this singularly quantum mechanical phenomena, fusors cannot in any manner, method or way become net energy devices due to the trivial amount of energy this process produces for the number of required energetic ions needing to be available in our tiny devices. Even the Sun produces an incredibly small amount of energy per cubic meter of incredibly dense, hot plasma - only its vast size allows significant energy to be available for us on Earth. Proposing that the laws of physics will suddenly change and a fusor can have 80% of all its ions undergo tunneling to create energy is pointless.

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