Waveform produced by a collapsing magnetic field

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The discussion centers around the electromagnetic radiation produced by an electron that instantaneously stops, leading to a collapse of its magnetic field. Participants explore the implications of infinite acceleration and the resulting electromagnetic (EM) waveforms, referencing the Lienard-Wiechert potentials to analyze the situation. They debate whether the simplification of the electron's sudden stop can accurately predict the radiation field, acknowledging that such idealizations often complicate the analysis. The conversation highlights the need to consider finite acceleration to avoid infinities in the solution and suggests that the emitted radiation will have a spectrum related to the deceleration curve. Ultimately, the complexities of the radiation field and its behavior near the light cone are emphasized, indicating that real-world scenarios require more nuanced modeling than the idealized case presented.
  • #31
Wow o_O

To try to begin to understand your method I drew a picture, I wondered if it agrees with what you had in mind (or whether it's completely off :wink:)? The red line is the worldline of the charge, and at ##t' = 0##, its 4-velocity is parallel to the ##t'## axis, so the charge is instantaneously at rest at this time in ##S'##. Also, the vector ##R## joining this event to ##E## is null, and thus parallel to the yellow lightcones.

1609627805563.png

How does that look?
 
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  • #32
That's it. Thanks - I was planning to draw a Minkowski diagram myself, but got side-tracked with the simplification stuff.

Looking at that, I wonder if I've got the wrong sign on my solution for ##v##, since it should be negative. I'll have a look tomorrow.
 
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  • #33
Constant proper acceleration is also among the more complicated examples. Even Pauli got it wrong (not so Sommerfeld, but this has been overlooked for some time). I think the resolution of the paradox that apparently there seems to be no radiation is given by Griffiths in

https://arxiv.org/abs/1405.7729
https://aapt.scitation.org/doi/10.1119/1.4875195
https://doi.org/10.1119/1.4906577 (Erratum)

Also in this case there are singular contributions to the fields, because the speed of the particle goes asymptotically to ##c##, and these conributions solve the problem.
 

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