Can Ion Trapping Approaches Effectively Contain Fusion Plasma?

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Discussion Overview

The discussion revolves around the feasibility of using ion trapping approaches, such as an orbitrap, for containing fusion plasma. Participants explore the principles of plasma confinement, particularly in relation to existing methods like tokamaks, and the role of electrostatic fields versus magnetic fields in achieving effective containment for fusion reactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the applicability of the Lawson criterion to the orbitrap in the context of fusion plasma containment.
  • Another participant notes that while electrostatic fields are effective for trapping ions, they are not used in tokamaks, prompting inquiry into the reasons behind this choice.
  • It is suggested that for fusion to occur, ions must collide at high speeds, implying that simple ion trapping would be insufficient.
  • Participants discuss the necessity of achieving high temperatures (around 10^8 K) and sufficient plasma density for effective fusion, raising questions about the role of electrostatic fields in maintaining plasma density.
  • There is a consideration of whether a plasma can maintain a net charge and how electron loss might affect stability and confinement.
  • Concerns are raised about the instability that could arise from losing too many electrons and the challenges of confining both hot electrons and ions simultaneously using electrostatic fields.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of electrostatic fields for plasma containment, with some arguing for their potential utility while others emphasize the challenges and limitations. The discussion remains unresolved regarding the optimal methods for fusion plasma containment.

Contextual Notes

Participants highlight the complexity of plasma behavior, including the interplay between temperature, density, and confinement methods, without reaching a consensus on the implications of these factors for ion trapping approaches.

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I've been reading some about the ITER project, tokamaks, and other approaches to plasma containment. Why can't ion trapping approaches such as an orbitrap be used for fusion plasma containment?
 
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Yes, I have been to both of those pages. I do not, however, know how to apply the Lawson criterion to the orbitrap.
 
I guess I'm trying to figure out why (from what I can tell) there are no electrostatic fields employed in a tokamak when such fields are so useful in trapping ions. It seems that great trouble is taken to use only magnetic fields.
 
In order for fusion to take place the ions have to collide at high speed. Trapping ions wouldn't work.
 
Clearly confinement alone is insufficient. You also need temperature on the order of 108K to generate high energy collisions (as you mention), plasma of high enough density that collisions occur frequently for a long enough time to have a good probability of some of them resulting in fusion. However I still don't understand why electrostatic fields wouldn't be very useful in containing the plasma at a decent density for long enough for fusion to commence. Clearly heating would need to be accomplished by some other means (not particularly relevant to my question).
 
undefined said:
Clearly confinement alone is insufficient. You also need temperature on the order of 108K to generate high energy collisions (as you mention), plasma of high enough density that collisions occur frequently for a long enough time to have a good probability of some of them resulting in fusion. However I still don't understand why electrostatic fields wouldn't be very useful in containing the plasma at a decent density for long enough for fusion to commence. Clearly heating would need to be accomplished by some other means (not particularly relevant to my question).

Does a plasma have a net charge?
 
Plasma consists of ions, which are all charged (and the basis for any confinement scheme). Fusion is only occurring between the nuclei, so if some electrons were lost, that wouldn't seem to be prohibitive. It seems clear to me that it wouldn't work to strip out all of the electrons simply because it would result in too much charge build-up. Wouldn't electron loss at some point naturally reach an equilibrium when the electrical potential of the plasma got high enough relative to the positive electrode?
 
Loosing too many electrons would still make the whole thing unstable. You cannot confine hot electrons and ions at the same time properly with electrostatic fields.
 

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