Abstract
BabyIAXO, a 20 m-long twin-bore helioscope aiming for search of axion like particles, is currently in the engineering design phase and its construction is to be completed within the next 4 years. In addition to X-ray detectors and focusing optics, the system is equipped with a 50 MJ magnet with a common coil layout, containing two 10 m-long NbTi flat racetrack coils cooled by a group of cryocoolers. It has to operate at 10 kA, preferably in persistent mode with disconnected power supply, allowing to simplify the sun-tracking rotation system of BabyIAXO. A direct current mode is possible as well. Hence, quench protection is a high priority. Here, we present the electrical circuit of the BabyIAXO magnet and its protection layout when operated in persistent mode. The quench process is calculated using a 3-D thermo-electrical model of the coil windings, also accounting for the presence of the coil casing and the quench-back effect. Impact of the operating current, conductor properties, voltage detection threshold and location of hot-spot on the peak temperature is discussed. Quench protection aspects of the HTS busbars and persistent mode switch are also addressed.
Highlights
One of the frontier activities in particle physics is the experimental search for theoretically predicted particles called 'axions', which existence would explain violation of symmetry in certain quantum models and may provide better understanding of dark matter
Quench protection of the BabyIAXO magnet when operating in persistent mode operation has been analyzed
The main mechanisms causing a fast-dump in the magnet like a quench in the coil windings, in the HTS busbars or in the persistent mode switch, have been evaluated
Summary
One of the frontier activities in particle physics is the experimental search for theoretically predicted particles called 'axions', which existence would explain violation of symmetry in certain quantum models and may provide better understanding of dark matter. The winding pack design of each racetrack, illustrated, is based on two stacked double-pancake windings using an 8-strand Al-stabilized NbTi Rutherford conductor of 20 mm width and 8 mm thickness. This magnet configuration when operated at 10 kA nominal current and 6.2 K current sharing temperature, yields a magnet’s figure of merit of 232 T2 m4 thereby fulfilling the design criteria of at least 200 T2 m4.
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