[Assistant-faculty] seminar regarding the magnets of the LHC machine

["Landis, Shannon R." <Shannon Landis tufts edu>]

Seminar 

Bray building (2nd floor conference room)
Friday March 25th 
11am

Speaker Dr. Ezio Todesco, CERN

It is well-known that superconducting magnets train, i.e., reach 
successively higher and higher current after successive quenching. It is 
general opinion that this training has mechanical origins, each quench 
setting the magnet in a mechanically more stable configuration. In this 
work we define a simple analytical one-dimensional model of stick-slip 
motion of the magnet coil. We show how this model predicts that the 
maximal magnet performance is asymptotically reached via a power law in 
the number of quenches. We then consider the large statistical sample of 
the training of individual dipoles are quadrupoles built for the CERN 
Large Hadron Collider, showing that this power law is verified over a 
large fraction of the training curves, i.e., in the range tending towards 
large field and large number of quenches. The very initial part of the 
training does not fit with this behaviour, but it can be described by a 
generalization of the above model.