Modeling the attenuation of RMP fields in TCABR plasmas due to eddy currents induced in the vacuum vessel

• Grant number: 24/11870-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): September 01, 2024
• Effective date (End): August 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics - Physics of Fluids, Plasma Physics and Electrical Discharge
• Principal Investigator: Gustavo Paganini Canal
• Grantee: Nathan Fabeliano Altaras
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/04857-2 - Development of an innovative set of ELM control coils for the TCABR tokamak, AP.JP

Abstract

A significant upgrade of the Tokamak à Chauffage Alfvén Brésilien (TCABR) is being designed to make it capable of creating a well controlled environment where the physics basis behind the effect of externally applied magnetic perturbations on edge localized modes (ELMs) can be addressed over a wide range of plasma scenarios, ELM control coil geometries and perturbed magnetic field spectra. The core of this upgrade corresponds to the design and construction of an innovative set of in-vessel ELM control coils composed of 54 coils on the high field side and 54 coils on the low field side, i.e. a total of 108 coils. These coils will operate with both direct current (DC) - up to 2 kA with 0 Hz - and alternating current (AC) - up to 1 kA with frequencies up to 10 kHz. In addition, all the coils will be installed inside the vacuum vessel to allow for fast 3D field pulses, with full coil current rise time smaller than 3 ms, for high time resolution studies of changes in pedestal profile properties. During AC operations, Foucault/eddy currents will be induced in the vacuum vessel causing a reduction of the amplitude of the perturbation fields in the plasma region. To properly design the TCABR ELM control coils, the effect of these eddy currents must be taken into account. Therefore, the ANSYS software will be used to estimate the attenuation of the perturbation fields due to these eddy currents. The specific objectives of this work, are to: (i) simulate the static (DC) magnetic fields produced in the plasma region by the TCABR ELM control coils; (ii) simulate the AC magnetic fields produced in the plasma region by the TCABR ELM control coils without accounting for the presence of the vacuum vessel; (iii) simulate the AC magnetic fields produced in the plasma region by the TCABR ELM control coils taking into account the eddy currents in the vacuum vessel; and (iv) identify a scaling for the perturbation field attenuation due to the eddy currents.