In the present scenario, the International Thermonuclear Experimental Reactor (ITER) is in progress and efforts are being made to extend ITER to DEMOnstration Power plant (DEMO) with the purpose to harness the fusion energy for peaceful and constructive purposes. ITER uses the sueperconducting magnet systems for trapping and maneuvering plasma inside the giant tokamak machines. Superconductivity only entails under the critical conditions of temperature, magnetic field and current density. If any of these parameters surpass the critical value, the quench ensues in the cable. In the real system scenarios, electromagnetic, radiative & conductive loads are present, which may affect the performance of the machine. The magnet designer can change the parameters in terms of current and magnetic field to ensure that the critical conditions are met, but when it comes to temperature, it is really hard to locate the hot spot locations. To envisage such situations, it is essential to study thermal hydraulics and hence system code is needed for the whole superconducting magnet system. For such purposes, Cryogenic Circuit, Conductor and Coil code (4C) was built, imbibing the thermal hydraulic modeling of the cable in Conduit conductors (including strands) coupled with structures (which give support to the winding pack, wound by conductors) and an external cryogenic circuit. During the thesis work, the pre-existing 4C code, was modeled for various coils with or without external cooling circuit as required. Henceforth, it was implemented against the wide range of transients, fast transients (~ few seconds) as well as slow transients (~ few days or weeks) to test the flexibility of the code in studying the wide range of physical phenomenon on different time scales. Eventually, the results were validated against the available experimental data to observe the precision of the model in 4C code. One of the analysis carried out during this dissertation included the cool down of one of the non planar coils (NPC) used in Wendelstein 7-X, which was an example of slow transient. In the domain of fast transients, an extensive analysis of AC losses in one of poloidal field (PF) coils with an external cooling circuit, was performed for Korean Superconducting Tokamak Advanced Research (KSTAR), functional fusion device.

Thermal Hydraulic numerical analysis of Fusion superconducting magnet systems / Kholia, Akshat. - STAMPA. - (2013). [10.6092/polito/porto/2507886]

Thermal Hydraulic numerical analysis of Fusion superconducting magnet systems

KHOLIA, AKSHAT
2013

Abstract

In the present scenario, the International Thermonuclear Experimental Reactor (ITER) is in progress and efforts are being made to extend ITER to DEMOnstration Power plant (DEMO) with the purpose to harness the fusion energy for peaceful and constructive purposes. ITER uses the sueperconducting magnet systems for trapping and maneuvering plasma inside the giant tokamak machines. Superconductivity only entails under the critical conditions of temperature, magnetic field and current density. If any of these parameters surpass the critical value, the quench ensues in the cable. In the real system scenarios, electromagnetic, radiative & conductive loads are present, which may affect the performance of the machine. The magnet designer can change the parameters in terms of current and magnetic field to ensure that the critical conditions are met, but when it comes to temperature, it is really hard to locate the hot spot locations. To envisage such situations, it is essential to study thermal hydraulics and hence system code is needed for the whole superconducting magnet system. For such purposes, Cryogenic Circuit, Conductor and Coil code (4C) was built, imbibing the thermal hydraulic modeling of the cable in Conduit conductors (including strands) coupled with structures (which give support to the winding pack, wound by conductors) and an external cryogenic circuit. During the thesis work, the pre-existing 4C code, was modeled for various coils with or without external cooling circuit as required. Henceforth, it was implemented against the wide range of transients, fast transients (~ few seconds) as well as slow transients (~ few days or weeks) to test the flexibility of the code in studying the wide range of physical phenomenon on different time scales. Eventually, the results were validated against the available experimental data to observe the precision of the model in 4C code. One of the analysis carried out during this dissertation included the cool down of one of the non planar coils (NPC) used in Wendelstein 7-X, which was an example of slow transient. In the domain of fast transients, an extensive analysis of AC losses in one of poloidal field (PF) coils with an external cooling circuit, was performed for Korean Superconducting Tokamak Advanced Research (KSTAR), functional fusion device.
2013
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2507886
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