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Blakut t1_is19jsd wrote

I would not think so since fluids follow the Navier Stokes equations, and do not have a wave like nature, but do have mass, while EM radiation follows the Maxwell equations, are waves, and have no mass. Simply put, you can't remove the EM field from an area. The only thing that comes to mind might be superconductors which eject an outside magnetic field passing through them, only to let it back 'in' suddenly when it's no longer a superconductor. I have no experience with supercomductors though.

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Sittes OP t1_it6qvz2 wrote

Thanks a lot for the explanation!

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chcampb t1_is21zal wrote

A definition

> Cavitation occurs when the hydrodynamic pressure exceeds the vapour pressure of a moving liquid. Gas bubbles form within the liquid, which thus becomes a two-phase system. These bubbles will be crushed against the metal surface at high speed, an attack that leads to cavities with rounded contours.

The reason for cavitation is usually because of turbulence. As an object moves through water it causes disturbances; if they are slow enough and viscous enough the local pressure differences are predictable and smooth. Whereas if you have mixing or an open system (ie not bounded by a pipe) with not very viscous liquid or very fast flow, you cause vortices and chaotic patterns, which cause local pressure differences and cavitation. It's sort of the difference between having smooth flow, where on a normal distribution, everything is pretty close to a certain pressure, and having chaotic flow, where the distribution of pressures is wider and some proportion of those pressure differences fall under the vapor pressure of the liquid.

Cavitation is interesting because of the mechanical properties of water which cause damage to systems. For electromagnetism you would need something similar, so ask questions like

  1. Are there any EM systems known for chaotic behavior?
  2. Do these chaotic EM systems cause damage to other systems?
  3. Bonus, are there any other EM systems that are known to cause damage?

For 1 and 2, yes, my understanding is that this is one of the major issues with plasma containment in fusion reactors (ie, ITER). In this case it may not be the EM itself that causes the issue, but the loss of beam confinement.

> Again, the nonlinear equations describing the motion of the plasma particles can exhibit chaotic behavior that allows the particles to escape from the confining fields. For example, electrons circulating along the guiding magnetic field lines in a toroidal confinement device called a TOKAMAK will feel a periodic perturbation because of slight variations in magnetic fields, which can be described by a model similar to the standard map. When this perturbation is sufficiently large, electron orbits can become chaotic, which leads to an anomalous loss of plasma confinement that poses a serious impediment to the successful design of a fusion reactor. source

Which brings me to 3) - it's far more common in electronics design to have to worry about inductive spikes, where semiconductors have to take PARTICULAR care against spikes exceeding a certain value. While this isn't chaotic, it is most similar to cavitation because a periodic spike, however rare, if it hits a semiconductor, it can damage the semiconductor over time. This can also cause EM - which is not chaotic, it's predictable, but because it's from so many traces it's likely to cause an exception in testing if you don't do clever things to spread the affected frequencies out. Too many switching supplies at exactly 1MHz for example will probably fail your test - it's a stochastic measure to spread that out over different frequencies and get better EMI results.

Ayway hope that answers some of the question.

Edit: citation

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Sittes OP t1_it6gmpj wrote

Thanks a lot for your detailed answer, very useful information!

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kilotesla t1_is3hzrm wrote

There isn't a direct analogy, but if we zoom way out and describe cavitation as a nonlinear effect that occurs when the amplitude of a disturbance gets too big (in the case of cavitation to large a magnitude of negative pressure relative to the pressure at rest), there are certainly nonlinear effects that occur when the amplitude of an electromagnetic wave is too large. Principally, dielectric breakdown which includes arcing in air and breakdown of solid insulators as well. Electromagnetic design for high power operation often includes avoiding dielectric breakdown, similar to how fluid designs often need to avoid cavitation.

That's often in high voltage transmission lines and other equipment for the power grid, but most of that design is quasi-static rather than being explicitly in the domain of wave effects. But in high power radio transmitters, the need for good impedance matching at each end of a line going from, for example, a transmitter at the base of the tower to an antenna at the top, is directly linked to the need to avoid standing wave effects that lead to high electric fields and dielectric breakdown. The effect is quantified by the standing wave ratio (SWR), which, when it's high, means that the peak electric field is higher than it needs to be by that factor.

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Sittes OP t1_it6r1gz wrote

Thank you, really interesting & appreciated!!

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LearnedGuy t1_is42k1y wrote

One effect that is interesting is the precession of organic (kerosene) molecules in a proton procession magnetometer. Ever time a square wave cycle is imposed on the hydrocarbon using a wrapping coil the protons align the the coil. When the square wave amplitude drops to zero the protons return to align with the Earth's magnetic field. But they don't snap back immediately because they are spinning. Instead they proceed back, and the precession can be read on the same coil as an imposed decaying sine wave. The stronger the Earth's field, the faster the precession takes place. Using a crystal oscillator as a reference the Earth's field can be read to 1 part in 50,000 (lambdas). Submarines sometimes use these measurements of known magnetic fields to navigate through undersea mountain ranges.

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Sittes OP t1_it6r371 wrote

Thank you, crazy interesting, never heard of it, I'm looking it up to learn more!

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