I was reading about topological insulators which can super-conduct electrons on their edges, I was thinking about this in relation to the high frequency skin effect. At a high enough frequency, the skin depth should be 1 atom deep on the conductor, and then the electron may have to travel on the "edge" only of the conductor, so there could be zero losses from resistance and supercondivity.
The losses would be 100% from emission from the vibrating AC electrons. At an infinite frequency the vibration amplitude of the electrons would approach zero, and radiation losses would approach zero. Does this make sense that losses from skin effect could start to decrease or am I thinking about it completely backwards?! :) Would it be possible to approach a high enough frequency where the radiation losses could be recovered?
On Thu, 21 Nov 2013 18:32:34 -0800, Jamie M Gave us:
Pretty skinny premise, man.
They have carbon films one atom thick that stop smaller atom gasses like Helium. A whole new technology will come out of this.
Line a bladder with a single layer of it, and it never leaks.
formatting link
So, we should be able to weave micro inductors now too.
Oh, and those finfets are cool too.
formatting link
My former boss's daughter came up with that one.(is that the right way to pluralize 'boss'?). And she started out wanting to do Cosmology (not cosmetology).
If you use two conductors separated by a thin insulator layer (nanometers) and run high frequency AC 180 degrees out of phase in them, will the radiated losses cancel out? If so then at high enough frequency maybe that could be a superconductor.
No. The skin effect you describe requires the current down inside to force the current to the outside and the current down inside will eat power.
To test your idea, use free simulation tool, femm 4.2, and try it out, you'll better understand where skin effect comes from. And learn a lot about magnetics.
The possessive form of boss is boss'. When the last letter is an 's' or a 'z', whether it's plural or not, the possessive form has a trailing apostrophe and no additional 's'.
Depends on whom you ask. Strunk & White says always to add "'s" regardless. Chicago Manual of Style says to add "'s" if the noun is singular, and just "'" if it's plural. The one constant in all this confusion is RWWATP.(*)
Cheers
Phil Hobbs
(*) Real Writers Write Around The Problem.
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
The current down inside that forces the current to the outside, is the AC induced eddy currents, and these eddy currents also move towards the skin at higher frequency, so at some high enough frequency even the eddy currents approach the outer layer of atoms on the conductor. Not sure what would happen in this case, but probably the AC eddy currents would create a plasma discharge or something off the surface?!
I thought about that just after posting. Should check using FEA and a model with a VERY thin surface layer of almost infinite conductivity and see what happens. Something must not work here, else a single layer of superconductivity would ALWAYS steal all the carriers so is not an easy thing to even understand.
Current does flow on the surfaces in superconductors, even at DC. The current layer has finite thickness, however, it's called the London penetration depth.
The current tries to distribute itself across the cross-section of the wire such that the stored energy is minimized. Each current filament can lower its energy by moving away from other filaments. One would then expect that all the filaments would move as far away from each other as they can, i.e. to the surface of the conductor.
Anyway, there is only a finite density of superconducting charge carriers available in a material. The smaller fraction of the cross-sectional area the current filaments occupy, the smaller number of carriers must carry the current, and the faster each carrier has to move. Because the carriers have mass, there is kinetic energy stored in their motion. This kinetic energy storage looks to the driving electric circuit exactly like inductance, hence it's called "kinetic inductance". However, the energy is stored as kinetic energy, not in the magnetic field. Therefore the kinetic inductance does not couple magnetically to other nearby inductors, either.
So, there is a tendency of the current filaments to move farther from each other, and thus reduce the stored magnetic energy. But by doing so they induce a larger and larger kinetic energy storage when the current gets packed to the surfaces. The two effects balance when the current distribution reaches (in the case of an infinite slab geometry IIRC) and exponentially decaying shape, with decay length equaling the London penetration depth. For our Nb thin films at LHe temperature this is roughly 90 nm.
If there are standards on every side of the argument, it sounds like a "real writer" can do it any way sheit pleases. "That's the nice thing about standards..."
I think a microwave waveguide is acting kind of like a topological insulator too, the microwaves reflect off the surface and don't penetrate, but still there is some interaction with the surface atoms that is near superconducting type.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.