Weakly Non-Linear Interaction Between Electromagnetic and Electrostatic Spectra in a Solar Wind-Type Plasma.
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Date
2025
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Universidad de Concepción
Abstract
En la teoría cinética lineal, los modos de onda electromagnéticos transversales y electrostáticos que se propagan a lo largo de un campo magnético de fondo B0 se consideran desacoplados y se ha estudiado su evolución de forma independiente. No obstante, en plasmas espaciales y astrofísicos reales, las interacciones resonantes entre ondas y partículas introducen no linealidades que rompen esta separación idealizada. Estudiamos la evolución cuasilineal acoplada de ondas Alfvén-ciclotrón (ACWs) y ondas ion-acústicas (IAWs) en un plasma de protones sin colisiones con distribución bi-Maxwelliana. Es de especial interés la razón de temperaturas entre electrones y protones (10 Te Tp 50) en cómo facilita la influencia indirecta entre estos modos de onda, además de estar en presencia de fluctuaciones del campo eléctrico constantes e independientes del campo magnético de fondo B0. Los resultados muestran que incluso una actividad moderada de ondas ion-acústicas puede acelerar el calentamiento perpendicular de los protones y favorecer la aparición temprana de inestabilidades electromagnéticas ciclotrónicas (EMIC). Este mecanismo representa una vía plausible y eficiente para la energización de protones en plasmas espaciales, con implicancias directas para el viento solar y la magnetósfera, donde tales condiciones son comúnmente observadas. Nuestros resultados contribuyen a ampliar y dar una mayor comprensión de las interacciones entre múltiples modos de onda y los procesos de transferencia de energía en entornos de plasma sin colisiones.
In linear kinetic theory, transverse electromagnetic and electrostatic plasma wave modes propagating along a background magnetic field B0 are treated as decoupled and evolve independently. However, in realistic space and astrophysical plasmas, resonant wave–particle interactions introduce nonlinearities that break this idealized separation. This thesis investigates the coupled quasilinear evolution of Alfvén-cyclotron waves (ACWs) and ion-acoustic waves (IAWs) in a collisionless, bi-Maxwellian proton plasma. Emphasis is placed on how the electron to-proton temperature ratio (10 Te Tp 50) facilitates indirect coupling between these wave modes, particularly when constant electric field fluctuations—independent of the background magnetic field B0—are present. The results demonstrate that even modest levels of ion-acoustic activity can significantly enhance perpendicular proton heating and promote earlier onset of electromagnetic ion cyclotron (EMIC) instabilities. This mechanism offers a plausible and efficient pathway for proton energization in space plasmas, with direct implications for the solar wind and planetary magnetospheres, where such conditions are commonly observed. The f indings contribute to a deeper understanding of multi-mode interactions and energy transfer processes in collisionless plasma environments.
In linear kinetic theory, transverse electromagnetic and electrostatic plasma wave modes propagating along a background magnetic field B0 are treated as decoupled and evolve independently. However, in realistic space and astrophysical plasmas, resonant wave–particle interactions introduce nonlinearities that break this idealized separation. This thesis investigates the coupled quasilinear evolution of Alfvén-cyclotron waves (ACWs) and ion-acoustic waves (IAWs) in a collisionless, bi-Maxwellian proton plasma. Emphasis is placed on how the electron to-proton temperature ratio (10 Te Tp 50) facilitates indirect coupling between these wave modes, particularly when constant electric field fluctuations—independent of the background magnetic field B0—are present. The results demonstrate that even modest levels of ion-acoustic activity can significantly enhance perpendicular proton heating and promote earlier onset of electromagnetic ion cyclotron (EMIC) instabilities. This mechanism offers a plausible and efficient pathway for proton energization in space plasmas, with direct implications for the solar wind and planetary magnetospheres, where such conditions are commonly observed. The f indings contribute to a deeper understanding of multi-mode interactions and energy transfer processes in collisionless plasma environments.
Description
Tesis presentada para optar al grado de Magíster en Ciencias con mención en Física.
Keywords
Landau damping, Plasma heating, Space plasmas