FAQ - Limits that keep amateurish plasma ideas from working
Posted: Sun Nov 26, 2017 3:25 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
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