Investigations of pulsed heat loads on a forced flow supercritical helium loop – Part A: Experimental set up

Cryogenic systems for future large superconducting tokamaks are expected to handle high pulsed heat loads due to cycling plasma operation. The superconducting magnets are cooled down with forced flow supercritical helium at 4.4 K and 5 bar. Cryogenic helium distributions can participate to the smoothing of pulsed loads and hence providing a stable interface with the refrigerator. An experimental set up named HELIOS has been designed and realized in CEA Grenoble to study pulsed load effects on a forced flow supercritical helium loop. The characteristics of the main components and the instrumentation with its calibration during reception tests are described in Part A. A first series of experiments was performed with pulsed loads in an isochoric configuration: large pressure and temperature changes in the circulating loop are observed, analyzed and compared as well to a thermohydraulic modeling described in Part B.

► Test facility to study the variable heat loads on large cryogenic systems.
► Design aspects for transient study with pulsed load operation.
► Cryogenic equipments are described: cold circulating pump, heat exchangers, thermal buffer.
► Instrumentation and calibration methods are presented.
► Heat load smoothing methods are discussed for future experimental campaigns.