Skin depth is roughly proportional to the square root of the ratio of resistivity to frequency. So lower resistivity (higher conductivity) means smaller skin depth, i.e., greater skin effect.
Jan, you once interviewed Dr. Vandenhul. Did you find him to be a quack? Is this something recent or have you thought so for years?
I met with Dr. Vandenhul about 30 years ago, he even gave me some wire samples. He was excited at the time with his 'discoveries' and he seems to have kept at it, over the decades. Doesn't he live near you? Maybe you should dig up some evidence against him. '-)
I met with Dr. Vandenhul about 30 years ago, he even gave me some wire samples. He was excited at the time with his 'discoveries' and he seems to have kept at it, over the decades. Doesn't he live near you? Maybe you should dig up some evidence against him. '-)
John,
I never said that Mr. Vandenhul was crazy, I actually like talking to him and we talked for a long time while we were in neighboring rooms. I just didn't hear anything special in those interconnects and didn't exactly think that his research was relevant to an audio cable. Somewhere I may still have his white paper on those wires but I haven't seen it in years. He was definitely an interesting man and we had much to talk about at the time.
I never said that Mr. Vandenhul was crazy, I actually like talking to him and we talked for a long time while we were in neighboring rooms. I just didn't hear anything special in those interconnects and didn't exactly think that his research was relevant to an audio cable. Somewhere I may still have his white paper on those wires but I haven't seen it in years. He was definitely an interesting man and we had much to talk about at the time.
Yes. In most cases, guys like that are either crooks or deluded. Worst case, they lighten the wallets of the gullible. By contrast, VdH sells quack medicine stuff, not just hifi. That put him in the realm of true evil.
What he was measuring was test residual. Same thing you found a few years ago with your tests. At that level of test, it is very important to consider return current path. It is very important to baseline your equipment, otherwise you end up chasing your tail.
If you can sell product based on flawed measurements, so much the better.
Personally, I would love for you to contribute. Whenever you start talking circuits, I listen. Granted, it's old history, but so much is lost.
Superconductors work by spreading the current based on the "critical current" of the material. Infinite conductivity means that the current will try to remain on the surface of the conductor. Since the conductor is only capable of a max current (defined as critical current density in kiloamps/mm2), it will skin at that current density. At any current, the current density at the surface will be exactly the critical current density. As the current increases, the current will consume more area, going deeper. When the area of the superconductor times the critical current density equals the current, the super is at what we call "short sample", or completely "full", any more current causes a quench.
A 1mm2 superconductor with a 2kA critical current, will quench at 2 thousand amperes. Typically, I use a wire about .036 inches diameter, or roughly #18awg to carry 2kiloamps no field, 1000 amps in fields up to about 6 tesla.
I also use small gauge super, roughly 28 gauge in size, for 200 amperes current.
jn
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