Speaker
Yawei Huang
(Institute of Research into the Fundamental Laws of the Universe)
Description
In order to check the performance of the JT-60SA Toroidal Field (TF) coils and hence mitigate their possible fabrication risks, a series of tests have been carried out in the Cold Test Facility (CTF) at CEA Saclay in nominal conditions at 5 K and 25.7 kA. One major test performed is the so called “temperature margin test" during which the inlet helium temperature of the winding pack is increased slowly with automation for approaching the calculated current sharing temperature of 7.3K in the high field region. For the first coils, the temperature is increased till the coil quenches. When the coil begins to quench, a Fast Discharge (FD) is triggered by the Magnet Safety System (MSS) which has a detection threshold of 100 mV - 100 ms. This allows to release all the nominal current from the coil to a Dump Resistance of 6.2milliohms with a time constant of about 10s. In the same time, the evacuation valves are opened to avoid any damages by overpressure in the coil or in the circuits. During this test, the voltage of each Double Pancake (DP) is registered by at a frequency of 10 kHz. This paper will present a study of the thermo-hydraulic behavior of the JT-60 SA coils during a quench thanks to the data coming from several quench experiments. It will analyze in particular the quench propagation velocity, the dissipated power in the coil and in the helium, the heated volume, the pressure rise in the helium and the operation of the safety valves.
Co-author
Yawei Huang
(Institute of Research into the Fundamental Laws of the Universe, CEA Saclay, Gif-sur-Yvette, France)
