A common term in superconductivity is "critical surface." The 3 axis are current, field, and temperature. If you are under the surface, the conductor is superconducting, if above, it is not.
If you had say a superconductor that had a critical temperature of 78 K in the field you are running it at, yes its resistance is zero but it wont be able to carry any significant current. What use is that? The point of superconductors is to move a lot of current (DC) with no loss. FYI superconductors do not have 0 impedance when carrying AC.
While HTS conductors are superconducting at 77K (liquid nitrogen) they will always work better the colder they are. That is why the new 32T all superconducting magnet at the NHMFL is submerged in a bath of liquid helium at 4.2K. Additionally, the HTS conductors are pretty expensive at $80 per meter. Apart from some really high field solenoids and other fairly rare magnet applications, there really isnt much of a killer app for HTS conductors. The utilities have been working on very high current density cables in the past but I am not aware of any ongoing programs right now.
For reference I will refer to a ReBCO conductor made by a company called Superpower that makes tapes that are 4mm wide and 0.1 mm thick. Keep in mind the actual SC layer is only 0.001 mm thick:
No background field and at 4 K you can run well over 1000 A through a tape with no loss
At 32 T and 4 K maybe 250 A or higher depending on field angle
And at 77K with no background field maybe only 200 A
Back in the 80s I think I remember seeing giant towers that used light to let people talk from Houston to Dallas in REAL TIME! I think we called them microwaves or are microwaves no longer light?
PS I did actually read the article (for once) and didnt see the frequencies that would be used
Elon Musk just invented 2-D batteries!!! If we fold the 1 square mile of batteries just right I can hold all of the power needed for the US in my pocket. But why stop there?
I know I am being pedantic but I just couldn't help myself.
I work at a fairly typical middle of the road state run university and we had our HR department basically tell us that if we suspect a crime has been committed, dont go to the police. Go to them instead because they have some investigative powers and dont have to (I am paraphrasing) worry about due process and rights of the accused. They justified it by saying that sure they can wreck your life, make your degree worthless, and take away what you have spent decades working for, but they didnt have the power to put you in prison. It was a chilling seminar and even a number of my very liberal coworkers were horrified.
Only loosely related, I had a student who had just recently started working at our facility tell me point blank "There are too many old white guys here" and "we need to get rid of some." Now couple that attitude with a kangaroo court and an ends justifies the mean attitude and you will see why a lot of people do not see the current university structure as a good thing.
What a condescending shit. As far as I am concerned his image is of a narcissistic schmuck that rolled the dice and got lucky but who is convinced of his own superiority.
So what the title is saying is that there are a bunch of overblown computer models with varying assumptions and cherry picked and massaged data to point to a plastic garbage problem? Thats a relief because be before I was concern about all of the plastic in the oceans.
Ok logged on and I fogot to tie the above comment to the article. Just as the aligned crystal structure in YBCO (for example) only gives you 2-D planes, it is the interface between the 2 materials in the article and their interactions that give you a 2-D superconducting plane. But just like any other superconductor, get it too hot or put it in a high magnetic field and it will change to a normal phase
The nuclear powered cruise missile you are thinking about was under development in the 60s as Project Pluto. It was to be a ramjet powered cruise missile that would carry multiple nuclear bombs and would act as more an automated bomber than what we would think of as a cruise missile. It was to fly very fast and had an unshielded reactor. It was thought that the radiation and the sonic booms would be lethal enough that one could simply fly them back and forth and not drop any bombs at all.
The split magnet mentioned in this story is a purely resistive magnet. This means that it will operate at room temperature and uses copper alloy coils (pretty sure its a copper-silver allow) along with a tremendous amount of current to generate a magnetic field. The resistive magnets at the NHMFL operate at up to 60,000A and at up to 500V which equates to about 30MW. This amount of power is difficult to dissipate and makes these some of the worlds most powerful hot water heaters. The coil technoloy used is known as Florida-Bitter. The tricky part about a split magnet is that you have to take the most efficient portion of the magnet, which are the coils close to the center and effectively move them to the farthest region of the magnet. For comparison, the most powerful resistive magnet at the NHMFL with comperable parameters generates 35T.
The most powerful persistant magnets however are the hybrids which have superconducting coils in the low field regions and resistive coils in the high field regions. The most powerful is 45T
A lot more information can be found at:
http://www.magnet.fsu.edu/
Slashdot Mirror
More information on the topic: https://www.bnl.gov/magnets/st...
A common term in superconductivity is "critical surface." The 3 axis are current, field, and temperature. If you are under the surface, the conductor is superconducting, if above, it is not. If you had say a superconductor that had a critical temperature of 78 K in the field you are running it at, yes its resistance is zero but it wont be able to carry any significant current. What use is that? The point of superconductors is to move a lot of current (DC) with no loss. FYI superconductors do not have 0 impedance when carrying AC.
While HTS conductors are superconducting at 77K (liquid nitrogen) they will always work better the colder they are. That is why the new 32T all superconducting magnet at the NHMFL is submerged in a bath of liquid helium at 4.2K. Additionally, the HTS conductors are pretty expensive at $80 per meter. Apart from some really high field solenoids and other fairly rare magnet applications, there really isnt much of a killer app for HTS conductors. The utilities have been working on very high current density cables in the past but I am not aware of any ongoing programs right now. For reference I will refer to a ReBCO conductor made by a company called Superpower that makes tapes that are 4mm wide and 0.1 mm thick. Keep in mind the actual SC layer is only 0.001 mm thick: No background field and at 4 K you can run well over 1000 A through a tape with no loss At 32 T and 4 K maybe 250 A or higher depending on field angle And at 77K with no background field maybe only 200 A
Actually guys I was joking. I am a solid windows user in a love/hate (more hate) relationship, but I need it for the ecosystem.
Dont need a magic 8 ball to see that one.
We have finally gone back to Hieroglyphics.
Back in the 80s I think I remember seeing giant towers that used light to let people talk from Houston to Dallas in REAL TIME! I think we called them microwaves or are microwaves no longer light? PS I did actually read the article (for once) and didnt see the frequencies that would be used
The best way to get to an Amiga fan boy is to tell them that Atari was first. Everyone has a button
Elon Musk just invented 2-D batteries!!! If we fold the 1 square mile of batteries just right I can hold all of the power needed for the US in my pocket. But why stop there? I know I am being pedantic but I just couldn't help myself.
I work at a fairly typical middle of the road state run university and we had our HR department basically tell us that if we suspect a crime has been committed, dont go to the police. Go to them instead because they have some investigative powers and dont have to (I am paraphrasing) worry about due process and rights of the accused. They justified it by saying that sure they can wreck your life, make your degree worthless, and take away what you have spent decades working for, but they didnt have the power to put you in prison. It was a chilling seminar and even a number of my very liberal coworkers were horrified. Only loosely related, I had a student who had just recently started working at our facility tell me point blank "There are too many old white guys here" and "we need to get rid of some." Now couple that attitude with a kangaroo court and an ends justifies the mean attitude and you will see why a lot of people do not see the current university structure as a good thing.
What a condescending shit. As far as I am concerned his image is of a narcissistic schmuck that rolled the dice and got lucky but who is convinced of his own superiority.
So what the title is saying is that there are a bunch of overblown computer models with varying assumptions and cherry picked and massaged data to point to a plastic garbage problem? Thats a relief because be before I was concern about all of the plastic in the oceans.
Was this suit filed by Green and Fazio per chance? https://www.nbc.com/saturday-n...
Ok logged on and I fogot to tie the above comment to the article. Just as the aligned crystal structure in YBCO (for example) only gives you 2-D planes, it is the interface between the 2 materials in the article and their interactions that give you a 2-D superconducting plane. But just like any other superconductor, get it too hot or put it in a high magnetic field and it will change to a normal phase
This reminds me of an old Saturday Night Live commercial called Yardapult. Cant seem to find it online though
The nuclear powered cruise missile you are thinking about was under development in the 60s as Project Pluto. It was to be a ramjet powered cruise missile that would carry multiple nuclear bombs and would act as more an automated bomber than what we would think of as a cruise missile. It was to fly very fast and had an unshielded reactor. It was thought that the radiation and the sonic booms would be lethal enough that one could simply fly them back and forth and not drop any bombs at all.
The split magnet mentioned in this story is a purely resistive magnet. This means that it will operate at room temperature and uses copper alloy coils (pretty sure its a copper-silver allow) along with a tremendous amount of current to generate a magnetic field. The resistive magnets at the NHMFL operate at up to 60,000A and at up to 500V which equates to about 30MW. This amount of power is difficult to dissipate and makes these some of the worlds most powerful hot water heaters. The coil technoloy used is known as Florida-Bitter. The tricky part about a split magnet is that you have to take the most efficient portion of the magnet, which are the coils close to the center and effectively move them to the farthest region of the magnet. For comparison, the most powerful resistive magnet at the NHMFL with comperable parameters generates 35T. The most powerful persistant magnets however are the hybrids which have superconducting coils in the low field regions and resistive coils in the high field regions. The most powerful is 45T A lot more information can be found at: http://www.magnet.fsu.edu/