Heavy Lifting — the Book of CFS just arrived

3 responses to “Heavy Lifting — the Book of CFS just arrived”

1. 

   jurvetson

   Feb 17, 2026 at 9:27 pm

   

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2. 

   sbove

   Feb 18, 2026 at 2:50 pm

   Amazing forces… and also worth noting that these so called High Temperature Superconducting tape-wire magnets made of REBCO (Rare-Earth Barium Copper Oxide), operate at 10k to 20k = negative 420 to 440 F Vs absolute zero 459 F.

   >> "A 20 Kelvin (K) superconductor is called "high-temperature" because it is "high-temperature" relative to conventional superconductors that require temperatures below 20 K—often near absolute zero to function. These materials signifiy a breakthrough in developing materials that operate above the previously assumed physical limits." – wikipedia

   "Early superconductors (discovered in 1911) needed liquid helium (4k) to operate. Materials that worked at 20k or higher were considered "high-temperature" because they broke the established, lower-temperature barrier." – GoogAI

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3. 

   sbove

   Feb 18, 2026 at 2:59 pm

   Also:

   The magnet windings in the SPARC tokamak are insulated from the extreme heat of the fusion plasma (over 100 million °C) through a combination of extreme magnetic confinement, cryostatic vacuum insulation, specialized shielding, and active helium cooling. Because SPARC uses High-Temperature Superconducting (HTS) magnets that operate at roughly 10 K to 77 K, maintaining this cryogenic temperature while the plasma burns requires a multi-layered protection strategy. – wikipedia

   Here is how the magnets are protected:

   Vacuum-Jacketed Cryostat: The entire superconducting magnet system is housed inside a massive vacuum chamber called a cryostat. Similar to a Thermos flask, this vacuum chamber ensures there is no air or gas between the hot interior of the tokamak and the cold magnets, virtually eliminating heat transfer through conduction or convection.

   Neutron and Thermal Shielding: A significant amount of space between the vacuum vessel (which contains the plasma) and the toroidal field magnets is filled with neutron shielding material. This shielding reduces the nuclear heating caused by high-energy neutrons produced during fusion, which would otherwise heat the magnets, causing them to lose superconductivity (quench).

   Active Cryogenic Cooling (Helium System): The HTS magnets are actively cooled by a cryogenic system that circulates helium at temperatures between 8 K and 15 K. This system acts as a heat sink, removing any heat that manages to pass through the shielding and vacuum.

   High-Field Magnetic Confinement: The intense magnetic field itself acts as the primary insulator, confining the hot plasma particles away from the physical walls of the machine.

   Divertor and Plasma-Facing Components: A divertor at the bottom of the vessel extracts heat and particles, reducing the heat load on the vacuum vessel wall and the shielding.
   – MIT www-new.psfc.mit.edu/sparc/hts-magnet

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