Frequency and electrons

[JGM_14]

Main Question or Discussion Point

Is there a frequency at which electrons do not flow (too high freq.)?
Fastest switching transistor- 508 Ghz

 

[Crazy Tosser]

Electrons flow as in assuming Newtonian mechanics in quantum space?
Or in wires?
What do you mean by flow?

 

[deakie]

i figue JGM means by current flowing through circuits....
if so, this is governed by the slowest device in the circuit....
however....this article shows a speed breakthrough at 410GHz....
http://www.sciencedaily.com/releases/2008/02/080207123348.htm

I'd like to think that they could break this barrier but maybe only at high costs.....

the research is concentrating in these areas now for the purpose of producing terahertz circuits and waves....and require a whole new mode of transmission line theory and materials...

i'm sure there is a point when the electron becomes more like a wave in the material and so technically....that would be raising the roof of possibilities....bearing in mind that electrons already travel at 'near the speed of light' in regular copper anyway....

 

[JGM_14]

the switching of the direction of the current in the wires becomes too fast so the electrons would not vibrate as in AC
Is it possible to happen at frequencies that super high?

 

[JGM_14]

flow as in electrons migrate from negative to positive, much in the way a river flowes from high ground to low ground the wires being the path that facilitates the water movement the low ground being the positive and the high ground the negative

 

[lightarrow]

the switching of the direction of the current in the wires becomes too fast so the electrons would not vibrate as in AC
Is it possible to happen at frequencies that super high?

If I remember correctly, an accumulation of charge inside a metal lasts less than about 10^(-15) s; it means we should go up to at least 10^15 Hz with frequency, that is to visible wavelenghts.

 

[JGM_14]

So the wire would "glow" at that high of frequency, or would photons not be emitted?

 

[pixchips]

I seem to recall that electrons actually diffuse very slowly in conductors, it's the fields that propagate quickly and nudge the electrons along the way ... wires are a long skinny sea of electrons that work more like an inside out waveguide rather than a copper water pipe. A particular electron doesn't ever get to go very far or very fast in a wire. Anyway, it's all kinda Newtonian whereas reality is more quantum. And then there is skin effect, which keeps currents (the electrons that get to participate in the propagation) very localized at high freqs. This dominates wires up to a gig or so, above that the dielectric losses make things worse. So I don't expect to see glowing wires anytime soon, except the kind that Edison made a while back.

 

[lightarrow]

So the wire would "glow" at that high of frequency, or would photons not be emitted?

The material would become insulating because it's as if the electrons couldn't move freely, however the classical description wouldn't be adequate anylonger and you should use the quantum one.

 

[deakie]

for those frequencies that copper wont be able to manage, they will have to introduce exotic materials and designs to cope.

 

[nuby]

How is the orbital frequency of a single atomic electron, and covalent electron, calculated?

 

[pixchips]

The material would become insulating because it's as if the electrons couldn't move freely, however the classical description wouldn't be adequate anylonger and you should use the quantum one.

The simplified theory of conductors and semiconductors uses 'conduction bands' and 'valence bands' to catagorize the energy of electrons in the material. Those are definitely quantum concepts. But the propagation of high frequencies along a wire are derived (I think) from classical E&M ... the external fields can only propagate so far in a conductor because of its super high index of refraction. Is there a quantum derivation of this? The probability that a photon of a given energy (wavelength) will penetrate to a given depth in a wire (modelled as a space charge constrained in a cylindrical potential well)? Perhaps there are tunneling solutions where regions of the conductor can participate in high frequency conduction and 'get around' the classic skin effect.

 

[atom888]

diamond reinforce composite wire! :surprised

 

[pixchips]

Umm ... yeah, didn't think of that. Maybe with tachyon beams????