3 ms·

I know essentially nothing about superconductors, but if they all have essentially zero resistance, what makes one better for this application? I thought the ma

by cultus 6y ago

I know essentially nothing about superconductors, but if they all have essentially zero resistance, what makes one better for this application? I thought the main advantage of high-temp superconductors was using liquid nitrogen instead of helium.

jjoonathan 6y ago
They still saturate. High-temperature is nice, but a separate consideration.
willis936 6y ago
HTS coils would still be run with liquid helium for higher critical current and higher magnetic field.
smaddox 6y ago
High temperature superconductors provide more stable resistance-free conduction than traditional superconductors. If both are cooled to liquid helium temperatures, that increased stability translates to being able to sustain a higher magnetic field. Higher magnetic fields provide tighter plasma confinement and higher density, which allows for much smaller fusion reactors.
mensetmanusman 6y ago
Think of it as the amount of energy you can store in a superconductor. This is talked about in terms of the ‘phase diagram for superconductors’ http://www.supraconductivite.fr/en/index.php?p=supra-levitation-phase-more http://www.supraconductivite.fr/en/index.php?p=supra-levitat... As you put more current in the supercondutor, eventually you break it and it leaves the mode, as it gets hotter, likewise, as the magnetic field gets stronger, likewise. You want the largest ‘area under the curve(s)’ to handle more and more ‘superconductivity’ New materials are enabling this which has the cubic effect mentioned for reducing confinement volume and making things more affordable and increasing energy densities that can be contained, etc.
sbierwagen 6y ago
All superconductors superconduct, but there's wide variation in how strong of a magnetic field they can endure before leaving the superconducting state: https://www.researchgate.net/figure/Upper-critical-fields-and-coherence-lengths-for-sev-eral-type-II-superconductors-The_tbl1_273297345 https://www.researchgate.net/figure/Upper-critical-fields-an... ITER (and the LHC) used NbSn magnets, since it was designed in the 90s. Newer designs will use newer superconductors.
- saalweachter 6y ago
  I want to emphasize this beyond upvoting. Superconductors are like magic, but they aren't actually magic. They have limits.

by cultus 6y ago

jjoonathan 6y ago

They still saturate. High-temperature is nice, but a separate consideration.

willis936 6y ago

HTS coils would still be run with liquid helium for higher critical current and higher magnetic field.

smaddox 6y ago

High temperature superconductors provide more stable resistance-free conduction than traditional superconductors. If both are cooled to liquid helium temperatures, that increased stability translates to being able to sustain a higher magnetic field. Higher magnetic fields provide tighter plasma confinement and higher density, which allows for much smaller fusion reactors.

mensetmanusman 6y ago

Think of it as the amount of energy you can store in a superconductor. This is talked about in terms of the ‘phase diagram for superconductors’ http://www.supraconductivite.fr/en/index.php?p=supra-levitation-phase-more http://www.supraconductivite.fr/en/index.php?p=supra-levitat... As you put more current in the supercondutor, eventually you break it and it leaves the mode, as it gets hotter, likewise, as the magnetic field gets stronger, likewise. You want the largest ‘area under the curve(s)’ to handle more and more ‘superconductivity’ New materials are enabling this which has the cubic effect mentioned for reducing confinement volume and making things more affordable and increasing energy densities that can be contained, etc.

sbierwagen 6y ago

All superconductors superconduct, but there's wide variation in how strong of a magnetic field they can endure before leaving the superconducting state: https://www.researchgate.net/figure/Upper-critical-fields-and-coherence-lengths-for-sev-eral-type-II-superconductors-The_tbl1_273297345 https://www.researchgate.net/figure/Upper-critical-fields-an... ITER (and the LHC) used NbSn magnets, since it was designed in the 90s. Newer designs will use newer superconductors.

saalweachter 6y ago
I want to emphasize this beyond upvoting. Superconductors are like magic, but they aren't actually magic. They have limits.