What can you tell me about wakefield plasma acceleration?

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    Acceleration Plasma
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Discussion Overview

The discussion centers around wakefield plasma acceleration, particularly its potential applications in space thrusters compared to existing technologies like VASIMR. Participants explore the efficiency of plasma acceleration methods and the implications of plasma density on performance.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant suggests that wakefield plasma acceleration could be more efficient for space thruster applications than the current ICH rf coupling used by VASIMR, proposing that higher speeds could lead to better electricity-to-force conversion efficiencies.
  • Another participant challenges this view, stating that plasma wakefield acceleration is primarily used for generating high gradient fields to accelerate charged particles, specifically electrons, and questions the feasibility of using it for space thrusters.
  • A participant inquires whether increasing plasma density could improve wall-plug efficiency or if experiments have been scaled up to test this.
  • Another response argues that increasing plasma density would require more energy input, potentially worsening the quality of the electron beam due to larger non-linear effects.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of wakefield plasma acceleration for space thrusters, with some advocating for its potential and others highlighting significant limitations. The discussion remains unresolved regarding the feasibility and efficiency of this approach.

Contextual Notes

Limitations include the current low wall-plug efficiency of less than 5% and the challenges associated with scaling experiments and increasing plasma density.

Eirhead
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I'm trying to read as much as I can about the topic. So I've read over wikipedia and watched some videos and such.

It seems to me, this method of plasma acceleration would be prime for space thruster applications. Right now VASIMR is using ICH rf coupling to accelerate their plasma. They should ditch that entirely and move to wakefield plasma acceleration if it's at all possible within in the context of their current design.

I'm not sure about the math behind this, but I'm under the assumption that the closer we get to relative speeds with ion ejection, the higher the efficiencies are going to be for Electricity to Force conversions (assuming the coupling efficiency remains the same). So let's stop wasting our time with 0.01% c plasma excitation, and really focus on getting to 50% - 99% c.

Whatever the electricity cost, I could really careless about, because if we can develop an engine strong enough for terrestrial liftoff, there will be limitless potential for where we can go with it and you'll really see progress ramp up!
 
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You have a severe misunderstanding about this principle.

The plasma wakefield acceleration so far is used to generate high gradient fields to accelerate charged particles, currently just electrons. Why you would want to use this for space thruster is very puzzling.

First of all, the wall-plug efficiency is extremely low (we're talking about less than 5% here). Secondly, so far, the technology can only accelerated very small electron bunches (significantly less than 1 nC per bunch), which isn't very much (but enough for many high energy physics applications). Try and figure out how much of a push you think you can get out of that many electrons.

Zz.
 
Ok, that's a smidgen of the type of information I'm looking for. Now if the plasma density were increased would it be possible to increase the wall-plug efficiency? Or alternatively, have an experiments been scaled upwards?
 
Eirhead said:
Ok, that's a smidgen of the type of information I'm looking for. Now if the plasma density were increased would it be possible to increase the wall-plug efficiency? Or alternatively, have an experiments been scaled upwards?

No, you'll just make it worse, because now you need to put in even MORE energy to create that plasma. Furthermore, the quality of the electron beam you will get will be worse, because the non-linear effects will be even larger.

Zz.
 

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