| The Vincenta code is used to simulate the pressure increases in helium in case of a quench in the superconducting
coils. We focus on two classes of coil in which helium is in direct contact with the conductor:
coils consisting of cable-in-conduit conductors (as in ITER or JT-60SA), in which supercritical helium is
forced through long channels; and bath-cooled coils, in which static helium is confined in short channels
perpendicular to the conductor and opening into a bath (as in Tore Supra or Iseult). Various physical phenomena
are responsible for the pressure increases in helium, which is subjected to strong heat flux in the
conductor during a quench: at the local level, i.e. in the heated channels, the inertial forces that must be
overcome to expel the fluid and the friction forces due to the induced velocity; at the global level, i.e.
throughout the cryogenic system, the adiabatic compression of non-heated volumes hydraulically connected
to the heated channels. Here we analyse the thermohydraulic behaviour of helium to highlight
the dominant phenomena, according to the geometry of the helium flow paths. The results are applied
to numerical simulation of the pressure rise in case of quench in a JT-60SA cable-in-conduit conductor
(CICC) and in the bath-cooled Iseult coil. |
