FAQ - Limits that keep amateurish plasma ideas from working

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Richard Hull
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FAQ - Limits that keep amateurish plasma ideas from working

Post by Richard Hull » Sun Nov 26, 2017 8:25 am

What follows is a FAQ written by Ian Krase that is a well done discussion of why many amateurish and innocent suggestions regarding plasma containment and confinement fail to pass muster due to the simple physics of a plasma. R.H.

Fusors are notable because they are extremely simple. A working fusor can be designed and built with very little mathematical study of its operation. It is well understood that fusors are very inefficient, but they are relatively easy to get working. The other common form of simple-to-design fusion reactor is the Beam-On-Target, (BOT), accelerator machine used in many commercial neutron generator fusion systems and also by http://www.rapp-instruments.de/Beschleu ... neugen.htm

From time to time, people have ideas for more complicated fusion systems. Unfortunately, these are often doomed to failure. People who do not know a fair amount of particle physics often don't realize just how damaging some of the losses and limitations inherent to plasma systems are, or how additional complexity can be counter-productive, especially without detailed modeling.


- Losses, losses, everywhere: There are a very large number of ways that your hard-earned energy can leak out of a system. Often, making things more complicated adds more ways for such leaks to occur. For power generation projects, trying to reach break-even, this steals the lifeblood of the system. For projects that are just trying to improve on the output of fusors or BOT, so called improvement ideas can actually turn what was hoped to be an improvement in efficiency into a net loss.


- Brehmstralung, Cyclotron, and Synchnotron Radiation: High energy charged particles do not like being decelerated or made to move in curved paths. Trying to do either can make them bleed energy in the form of X-rays. This means that any use of magnetic lenses to bend or focus plasma, or any use of electrostatics to decelerate particles may create a very large loss (and an extra source of radiation).

- Brillouin Limit and Space Charge: Because of repulsion between like charges, there is a sharp limit on how dense one can make a plasma, (with a given strength of magnetic and other containment forces). Many plasmas will not be neutral, exacerbating the problem. Making magnetic containment or focusing fields more powerful tends to run into the previous problem with cyclotron radiation losses.

- Self-defocusing beams: Repulsion in a non-neutral particle beam will make it spread out. Beams passing through each other or a cloud of gas or plasma will also spread out. Both of these lead to problems with systems that try to use a beam of particles more than once.

- Getting magnetic arrangements right is remarkably difficult and almost always requires detailed mathematical modeling.


It is worth noting that many of these issues are also problems for ion thrusters in space and for some types of energy weapons, as well as making the Bussard Ramjet a scheme of questionable practicality.

Ian Krase
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: FAQ - Limits that keep amateurish plasma ideas from working

Post by Dennis P Brown » Sun Nov 26, 2017 11:57 am

The real and ultimate reason all attempts to exploit realistic energy production from a fusor are doomed to fail.
In any and all fusor's the mechanism that creates fusion energy is essentially based upon quantum mechanical tunneling (unlike, say, tokamak methods of brute force used to overcome the Coulomb barrier.) This tunneling process has an extraordinarily low probability of occurring in any realistic situation - even in the Sun's core! That is, in the Sun this tunneling effect is what produce essentially all its energy and requires a vast size and incredible density to achieve its energy production. For instance, In the Sun's core the temperatures is only 15.7 million Kelvin - far too low to create any significant energy by the 'conventional' process of proton-proton fusion.

To better see the issue of how rare an energy producing process tunneling based fusion can be consider the energy production rate in the core of the Sun - here a cubic meter of this 15.7 million K ultra-dense plasma (almost 10^+27 nuclei/cc) produces just 276.5 Joules/sec or Watts of power! Your oven is far away a greater energy producing source. So fusion via tunneling, even under these unimaginary extremely high temperatures and density conditions is still amazingly small!

This issue of tunneling to create fusion energy, more than any other, is what dooms any attempt to create extractable (usable) energy from a fusor - even if one increased the plasma density many orders of magnitude, the energy released would still remain undetectable. No design or clever magnetic confinement will change the fact that fusion via tunneling is so extraordinary rare (even in the Sun's core!) that energy production methods just will not be viable.

This simple fact of physics explains why scaling a fusor, no mater how well it contains its plasma along with ultra "clever" methods to even eliminate all the machine's innate loss mechanisms (i.e. Brehmstralung, Cyclotron, and Synchnotron Radiation, or Brillouin or Space Charge limitations and really any other problem one might consider) or using 'virtual cathodes' will never really matter and any attempt to get usable energy from a fusor based system is doomed to failure.

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Re: FAQ - Limits that keep amateurish plasma ideas from working

Post by Richard Hull » Mon Nov 27, 2017 5:46 am

It is obvious to the adroit that any net fusion energy attempt must be many orders of magnitude beyond that of the Sun's capability on a volumetric basis. This has been noted before in these forums. Stars are a terrible example of fusion efficiency, quite possibly one of the worst fusion engines one could hope to imagine. Still, the universe is full of these bloated fusion engines, not having any realization of just how terrible they are at it. Like bees, the stellar furnaces go about their busy way, using what quintillions of tons of fusion fuel that are at hand and the great potential energies of gravitation and electrostatics to blunder into fusion. After all it is just simple physics!

If man is to do controlled nuclear fusion to achieve a usable energy source, doing it the way the sun and stars do it is the worst way to go about it. There is little hope of doing it in the manner it is currently being done on planet earth.

The original post here is all about the doomed effort of the ill-informed, mistakenly figuring to improve the fusor through some trick artifice within the plasma.

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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