Quench protection of magnetic field accelerator magnets poses significant challenges. Maintaining the hot-spot temperature and peak voltage to ground within acceptable limits requires a protection system that actively transfers most of the coil turns to the normal state.
A new quench protection method called Energy Shift with Coupling (ESC) is presented, which appears very promising for protecting the next generation of accelerator magnets.
ESC relies on normal-conducting auxiliary coils that are strongly magnetically coupled with the magnet coils to protect. Upon quench detection, capacitive units are discharged across the auxiliary coils causing a rapid shift of magnet stored energy from the magnet coils to the auxiliary coils. This has three main effects: sudden reduction of ohmic loss in the magnet conductor, introduction of high transient losses in the superconductor causing quick transition to the normal state, and extraction of a part of the magnet’s stored energy to the auxiliary coils.
Simulations show that ESC can be utilized to protect full-scale magnets with manageable requirements in terms of size and location of the auxiliary coils, and of capacitive unit parameters. Excellent quench protection performance in terms of hot-spot temperature and peak voltage to ground can be achieved while relying on a method that does not require any electrical connection nor physical close contact with the coils to protect.
The applicability of the ESC concept to various existing and future magnet designs is discussed. Various design and operation parameters that affect its performance are investigated. Its advantages and disadvantages method are addressed and compared to other traditional quench protection methods.