Can a beam of light guide or manipulate electrons in motion?

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Discussion Overview

The discussion explores the concept of whether a beam of light can guide or manipulate electrons in motion, particularly in the context of an experiment where electrons are emitted towards a detection wall. Participants consider the implications of introducing a light beam into the path of these electrons and its potential effects on their trajectory and distribution upon detection.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions if a beam of light can influence the travel of electrons, suggesting that an electromagnetic wave might affect the trajectory of moving charges.
  • Another participant references free electron lasers (FELs) and notes that these devices use magnetic tubes to guide electrons, questioning if a similar effect could be achieved with light.
  • A later reply indicates that the interaction between light and electrons could lead to scattering effects, which may reduce the density of both photons and electrons at the detection wall, suggesting this would not result in guiding the electrons.
  • Additionally, the concept of optical tweezers is mentioned, which can manipulate macroscopic objects using light, implying that the dynamics might differ for larger entities compared to electrons.

Areas of Agreement / Disagreement

Participants express differing views on the potential for light to guide electrons, with some suggesting possible effects while others highlight the limitations and countereffects of such interactions. The discussion remains unresolved regarding the feasibility of using light for this purpose.

Contextual Notes

The discussion involves assumptions about the behavior of electrons in electromagnetic fields and the specific experimental setup, which are not fully detailed. The implications of scattering and the effectiveness of light in guiding charges are also not conclusively established.

Sturk200
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Can electrons be "guided" or "carried" by a beam of light, something in the manner of how a ship can be guided by a current? So suppose we emit a uniform field of electrons. I don't know if field is the right word. I mean a bunch of electrons of more or less uniform distribution are being shot at a wall that is capable of detecting them. When we detect the electron strikes on this wall, we unsurprisingly find a uniform distribution. Now introduce a thin beam of light shining down the center of this distribution of electrons, towards the wall, and run the experiment again. Will this beam of light have any effect on how the electrons travel and how they strike the wall? Will there, for instance, be a greater density of electrons detected where the light is shining?

I am asking because it seems like an electromagnetic wave shined in the path of a moving charge should have some effect on the trajectory of the charge. And I'm wondering if this kind of mechanism could be used to guide or aim a charge?

Thanks for your help!
 
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Are you familiar with free electron lasers (FELs)?
 
berkeman said:
Are you familiar with free electron lasers (FELs)?

I just Wiki'd it. Thanks for the reference.

But it looks like this is a device for shooting or guiding a beam of electrons using some kind of magnetic tube. I was wondering if something similar could be accomplished with a beam of light, so the electron would run along the path of the light, rather than along the length of a magnetic-field-tube.
 
It depends on the setup. The light can scatter at the electrons, reducing both the photon and the electron density at the wall in the bright spot (as both get transverse momentum).
That's the opposite of "guiding".

For (small) macroscopic objects, things can be more interesting - you can move them around by manipulating a beam of light. See optical tweezers.
 

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