Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Strategies & Market Trends : ahhaha's ahs -- Ignore unavailable to you. Want to Upgrade?

To: Bilow who wrote (2325)	5/19/2001 9:41:07 PM
From: Ahda	Read Replies (1) \| Respond to of 24758

Carl in Japan they were doing extensive research on super conducting materials which was the original question posed by DMV. Much of this research has been halted due to tech spec and less funds to spec with. The conversations here rotates to energy. If that energy can be addressed in any other super conductive anything solar panels extra it is helpful. Speaking of which i have a mess on my computer. Word won't load. The me systems configuration is not accepting i have deleted things and I can't get NAV or work can't reinstall but get an old message when the darn program starts that states can't initialize the virus scanning program. Word can't launch because of an error in task unless some simple minded Einstein's can co operate with Dali Lama creatures like me the tech industry is in deep doo doo. whose fault MSFT i think simple should be the least complex Systems in the world with error covered. Either that or i can plug in somewhere and get fixed if hackers can hack in why can't i get into some where and have fixed that which frustrates me to no end. I can spend six hours at the SEC. Why? I might eventually have ATHM aced, This computer tech is not enjoyment this is hell. Why should people like me have to waste their time on that which creates frustation big time. Hello msft windows me, from my clouded observation point. Windex anyone ?

To: Bilow who wrote (2325)	5/20/2001 5:13:20 AM
From: frankw1900	Read Replies (1) \| Respond to of 24758

Right, now I'm in a bad mood. I answered this post already and my computer crashed. Lets take this one step at a time. You write: superconductors have a current limitation, rather than a power limitation They have both. First sentence I quoted:"Superconductors, because of their sharp transition from zero resistance at normal currents to finite resistance at higher current densities, are tailor-made for use in FCLs [Fault Current Limiters] The next paragraph I quoted said superconductors (SCs) have three areas. One is the area where resistance is essentially zero. Around it is an area in which resistance rises sharply ("transitional state"). And outside that an area in which the resistivity is independent of field and current density as in normal conductors. I then stated current density is ampere per square meter. Therefor cross section is important: If great enough current density is supplied, superconductance will disappear due to the generation of heat (= power). Because at the margin, resistance is NOT zero, and 'ordinary' high temperature rules apply. Friday eveningt after answering Ah's question and reading the rest of the replys I went to a concert and met a physicist and asked this question, "Superconductors. If R is zero how do you calculate I as in E=I*R?" Her answer was, "It's not really zero, there is residual motion." Then she bugged off and I couldn't ask her anymore naive questions. So I had to think. It's been a while since I read an explanation of superconductance but it was framed in terms of tunneling effect analogous to that of semiconductor devices. This is a quantum process and subject to non linear effects. Thus some small (residual) motion in the SC material can cause resistance which can can cause further resistance through heating (power) this 'catastrophe' making the material have localized hot spots as mentioned in the article. Impurities or inhomogeneity can further agravate this tendency. AC or DC, it happens. High temperature or low temperature SCs, it happens. Low temp SCs are good heat conductors and the hot spot (resistance) propagates down the wire (hundreds of meters per second). High temp are poor heat conductors so the hot spot sits there - this can be overcome by coating the SC with a good heat conductor such as silver (expensive and heavy). It will also carry away the excess current, if it doesn't melt. Designing a SC device requires taking into account not only the SC's current density carrying characteristics but its power carrying capacity. Have to overdesign the refrigeration and the 'circuit breakers' due to high current carrying capacity and extremely rapid build up (microseconds) of nonlinear effects (resistance/hotspots) which must be damped. No free lunch. As I said, life in a high current superconducting lab might sometimes be quite exciting.