Nowadays, superconducting magnets are more and more used for applications related to the future energy. Indeed, they represent one main component of the so-called "Tokamak" machines which goal is to produce one day electricity from thermonuclear fusion energy. In order be in a superconducting state and to transport high current densities, these magnets are cooled by supercritical helium at a temperature of 5 K. However, a disturbance or fault in the machine could induce a heat deposition on the conductor and make it transit from his superconducting state to a normal resistive state. Once the conductor is resistive, the high current passing in it induces high heat deposition by joule effect and thus a transition of the conductor lengths close by. This transition chain reaction of the conductor from its superconducting state to its normal state is called "Quench". In the Framework of a collaboration between Europe and Japan, 20 superconducting magnets of the JT60SA Tokamak were tested by CEA under their nominal operating conditions (25 kA and 5 K). Quench experiments have been performed on each one of them. The PhD work will consist first in the physical analysis of the data obtained during quench experiments and the identification of the physical phenomena taking place during a quench. Then the PhD student may propose and carry out new complementary experiments allowing him to better understand the main thermo-hydraulic phenomena taking place. Finally, the PhD student will have to build a numerical model that reproduces and predicts the behavior of the magnets during a quench experiment. This model will be implemented in and existing industrial software.