Considering EM radiation as waves, how many particles can interact with one "ripple"? As far, as I understand, in quantum field theory one photon can't be absorbed by to particle systems like atoms, or can't be scattered on two single particles, like free electrons.

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*If to consider electromagnetic radiation as distribution of changes of values of electromagnetic field at space, i.e. as a wave, how many particles then, can interact with "one same" radiation?


*fig 1 - Example, emerald circles - em waves, pink dots - electrons
What will happen in the case, illustrated above? Will one (random?) of two electrons somehow interact (scatter) with the wave, and just after that the second one will lose ability to interact with the same wave, because the last one will disappear? Or will they both interact with em wave simultaneously?


*How does it corresponds with considering em radiation as a particle - photon?


My thoughts
If to consider an em wave as literally changes of electrical field strength values at some points at some time, then two electrons must be affected by same em field, and simultaneously (considering the case, illustrated above).
Some stuff is intuitively proving it, like Huygens–Fresnel principle.
Or the fact that all light sources, as I understand always emit light radially (or spherically, do not know hot to call it) in all directions, even lasers. It can be narrowed (like in case of laser), though it still will diverge.
And, considering the fact from paragraph above, I've read somewhere, and it should be logical, that if em radiation is infinitely "stretches", and at the same time its energy is constant, then, energy (and hence $E$) per area unit should decrease.
If $E$ per area is considering by someone in physics, that means that particles per can absorb not whole em wave, but only part, that corresponds to the area, that particle is occupying.
 A: In classical theory, EM wave interacts with all particles that are reached by the wave, there is no limit to the number of particles. Irrespective of the number of particles, energy obeys the law of local conservation of energy (sum of energy of EM field and energy of particles).
This is as far from EM radiation being a stream of particles as you can imagine. And even in quantum theory of radiation, EM radiation is not a stream of particles. It is a field, sometimes a nice wave, and only its interaction with matter particles manifests photon behaviour.
A: You might look at Thomson scattering, the classical interaction of an electromagnetic wave with a single charged particle.
Response to comment:
Trying to understand the collective interaction of a bunch of electrons with a photon is the hard way to do it. But in quantum mechanics electromagnetic radiation propagates as waves, and classical wave calculations are insightful, while quantum calculations can get lost in unnecessary abstraction. I suggest you study the variety of waves in plasmas to understand a common sort of interaction of electromagnetic waves with free electrons. Save the photon idea for the interaction with a detector.
