Simulación de escenarios de calentamiento por microondas para conocer las condiciones de la propagación de ondas de Bernstein electrónicas en el plasma del stellarator SCR-1
Fecha
2024
Tipo
tesis de maestría
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Solano Piedra, Ricardo
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El Laboratorio de Plasmas para Energía de Fusión y Aplicaciones del Tecnológico de Costa Rica alberga al Stellarator de Costa Rica 1 (SCR-1), el primer stellarator modular en Latinoamérica. Enfocado en la investigación de nuevas estrategias del calentamiento del plasma, actualmente se concentra en la generación de ondas de Bernstein electrónicas para alcanzar densidades electrónicas elevadas, con campos magnéticos bajos. Este enfoque ha demostrado ser efectivo en otros dispositivos de confinamiento magnético en la comunidad de fusión. El propósito de este trabajo es definir las características del plasma, el dispositivo de confinamiento magnético y la radiación incidente necesarios para la generación de ondas de Bernstein electrónicas en el plasma del SCR-1.
La caracterización del SCR-1 comenzó con un análisis detallado de sus componentes y su proceso de descarga. Utilizando mediciones directas con la sonda simple de Langmuir, se obtuvieron perfiles radiales de densidad y temperatura electrónicas. Los resultados indicaron que la densidad electrónica máxima se mantuvo dentro de los límites teóricos, mientras que el código VMEC reveló un equilibrio magnetohidrodinámico con un bajo parámetro beta y una estabilidad lineal determinada mediante el criterio de Mercier.
Se evaluó la viabilidad de las ondas de Bernstein electrónicas mediante simulaciones en tres escenarios de calentamiento diferentes, utilizando el código IPF-FDMC. Las simulaciones se basaron en las características del SCR-1 y ajustaron la densidad electrónica para lograr un plasma sobredenso. Se determinó que la curvatura del plasma y las longitudes de escala característica influyen en la conversión O-X del plasma del SCR-1, alcanzando un máximo del 63 % de conversión. Sin embargo, se identificaron dos de los tres mecanismos de amortiguamiento que podrían afectar la conversión X-B, donde está la conversión SX-FX, colisiones electrónicas y el calentamiento electrónico estocástico. Estos factores podrían reducir significativamente la porción del modo extraordinario lento, posiblemente impidiendo la generación del modo de Bernstein.
The Plasma Laboratory for Fusion Energy and Applications at the Costa Rica Institute of Technology is home to the Stellarator de Costa Rica 1 (SCR-1), a modular stellarator and the first of its kind in Latin America. Focused on researching new plasma heating mechanism, it currently focuses on generating electronic Bernstein waves to achieve high electron densities with low magnetic field. This approach has been proven effective in other magnetic confinement devices in the fusion community. The purpose of this work is to define the parameters of the plasma, the magnetic confinement device and the incident radiation necessary for the generation of electron Bernstein waves in the SCR-1 plasma. Characterization of the SCR-1 began with a detailed analysis of its components and discharge process. Using measurements with the Langmuir single probe, radial profiles of electron density and temperature were obtained. The results indicated that the maximum electron density remained within theoretical limits, while the VMEC code revealed a magnetohydrodynamic equilibrium with a low beta parameter and linear stability determined by the Mercier criterion. The feasibility of electronic Bernstein waves was evaluated through simulations in three different heating scenarios using the IPF-FDMC code. The simulations were based on SCR-1 characteristics and adjusted electron density to achieve overdense plasma. It was determined that plasma curvature and characteristic length scales influence the O-X conversion in the SCR-1 plasma, reaching a maximum conversion of 63 %. However, two out of three damping mechanisms were identified that could affect the X-B conversion, including SX-FX conversion, electron-ion and electron-neutral collisions, and stochastic electron heating. These factors could significantly reduce the slow extraordinary mode waves fraction, possibly hindering Bernstein mode generation. Therefore, the need for environmental conditions favoring an appropriate electron density scale length and increased radiation power for the O-X-B mechanism is emphasized.
The Plasma Laboratory for Fusion Energy and Applications at the Costa Rica Institute of Technology is home to the Stellarator de Costa Rica 1 (SCR-1), a modular stellarator and the first of its kind in Latin America. Focused on researching new plasma heating mechanism, it currently focuses on generating electronic Bernstein waves to achieve high electron densities with low magnetic field. This approach has been proven effective in other magnetic confinement devices in the fusion community. The purpose of this work is to define the parameters of the plasma, the magnetic confinement device and the incident radiation necessary for the generation of electron Bernstein waves in the SCR-1 plasma. Characterization of the SCR-1 began with a detailed analysis of its components and discharge process. Using measurements with the Langmuir single probe, radial profiles of electron density and temperature were obtained. The results indicated that the maximum electron density remained within theoretical limits, while the VMEC code revealed a magnetohydrodynamic equilibrium with a low beta parameter and linear stability determined by the Mercier criterion. The feasibility of electronic Bernstein waves was evaluated through simulations in three different heating scenarios using the IPF-FDMC code. The simulations were based on SCR-1 characteristics and adjusted electron density to achieve overdense plasma. It was determined that plasma curvature and characteristic length scales influence the O-X conversion in the SCR-1 plasma, reaching a maximum conversion of 63 %. However, two out of three damping mechanisms were identified that could affect the X-B conversion, including SX-FX conversion, electron-ion and electron-neutral collisions, and stochastic electron heating. These factors could significantly reduce the slow extraordinary mode waves fraction, possibly hindering Bernstein mode generation. Therefore, the need for environmental conditions favoring an appropriate electron density scale length and increased radiation power for the O-X-B mechanism is emphasized.
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