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Learn how superconductive magnets in the LHC work, what happens if protons collide with them, and the crucial safety measures involved. Discover the role of niobium-titanium wires, temperature requirements, and the use of superfluid helium for cooling to prevent catastrophic breakdowns. Understand the process of diverting proton beams to ensure safe operation of the giant magnet. Stay informed and stay safe with this informative guide from CERN.
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Avoid accidents with superconductive magnets in LHC. What if protons collide with the magnets?
An important diagram • Only under the 2 dimensional surface in a 3 dimensional space the material used for the wires of the magnets, niobium-titanium, is superconductive • This surface is determined by temperature, magnetic induction and current density. CERN HST 2001
An important diagram(2) • To be save it is necessary to stay far from the surface, it limits current densities, magnetic induction and temperature. • In LHC B must be some 9 T, current some 13 000 A, so a temperature below 2 K is needed for safety reasons CERN HST 2001
What happens if a proton hits the magnet? • Sometimes a proton could hit de side of the tube, hitting a superconducting magnet • The collision point heats up • This spot is no longer superconductive CERN HST 2001
This means on the diagram • If the temperature of the spot rises higher than 5 K, Niobium-titanium no longer is superconductive. CERN HST 2001
Catastrophy? • Heat due to Ohm’s law is generated • This causes the non-superconductive spot to become larger quickly, and more heat is generated • Etc... • The experiment breaks down CERN HST 2001
Unless... • The heat of the initial collision spot is taken away. • Superfluid helium takes care of that: • it flows all over, the magnets swim in this fluid • the heat capacity of helium becomes larger with lower temperatures, one of the reasons why the temperature is so low CERN HST 2001
As a consequence • The helium must flow constantly and cool permanently, taking the heat of accidental collisions away • The circuit should continuously be able to cool all helium to this low temperature • They will need 5000 tons of helium in this giant magnet, the production of the whole world during one year CERN HST 2001
If this is not enough • The beam must be taken out of the tubes • A kicker magnet kicks the 2850 bunches of protons into a larger magnetic field, allowing the protons to bend into a pipeline of 100m long. • Another magnet disperses the proton bunches to bigger surfaces to collide with, the energy is absorbed by special materials (mainly graphite) at the end of the tunnel CERN HST 2001