@MastersThesis{InostrozaLara:2020:MoPaCa,
author = "Inostroza Lara, Ana Mar{\'{\i}}a",
title = "Movimento de part{\'{\i}}culas carregadas, com velocidades
relativ{\'{\i}}sticas, sob a{\c{c}}{\~a}o de campo
geomagn{\'e}tico perturbado",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2020",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2020-03-26",
keywords = "el{\'e}trons relativ{\'{\i}}sticos, cintur{\~o}es de
radia{\c{c}}{\~a}o, ondas chorus, campo geomagn{\'e}tico
perturbado, relativistic electrons, radiation belts, chorus waves,
perturbed magnetic field.",
abstract = "O campo magn{\'e}tico da Terra varia dependendo das
condi{\c{c}}{\~o}es da magnetosfera e a din{\^a}mica das
part{\'{\i}}culas presentes. Quando as part{\'{\i}}culas
est{\~a}o no campo magn{\'e}tico descrevem tr{\^e}s movimentos
principais: giro ao redor da linha de campo; repique entre os
pontos de espelhamento nos hemisf{\'e}rios e a deriva em torno da
Terra, e a cada um destes movimentos est{\'a} associado uma
quantidade f{\'{\i}}sica denominada invariante adiab{\'a}tico.
Se n{\~a}o existe uma perturba{\c{c}}{\~a}o no campo, a
part{\'{\i}}cula permanecer{\'a} aprisionada. No entanto, na
aus{\^e}ncia de perturba{\c{c}}{\~o}es externas, existem certos
limites nos quais os invariantes adiab{\'a}ticos s{\~a}o
quebrados. Neste trabalho, conseguiu-se obter que, para
part{\'{\i}}culas teste com energias entre 2 e 5 MeV, que
iniciam sua trajet{\'o}ria na posi{\c{c}}{\~a}o maior a 7RE,
pode existir perdas de part{\'{\i}}culas, dependendo de sua
energia. Existem certos mecanismos que podem gerar perdas de
part{\'{\i}}culas, sendo um deles a intera{\c{c}}{\~a}o com
ondas chorus. As ondas chorus s{\~a}o um tipo de ondas whistler
com polariza{\c{c}}{\~a}o RCP (Right-hand Circularly Polarized)
que se propagam em dire{\c{c}}{\~a}o paralela ao campo
magn{\'e}tico da Terra com frequ{\^e}ncias entre centenas de Hz
at{\'e} alguns kHz. Enquanto se propagam, podem interagir com
el{\'e}trons energ{\'e}ticos relativ{\'{\i}}sticos do
cintur{\~a}o de radia{\c{c}}{\~a}o Van Allen, quando se cumpre
a condi{\c{c}}{\~a}o de resson{\^a}ncia, o que pode causar
perdas dos el{\'e}trons. Este trabalho tem como objetivo avaliar
a varia{\c{c}}{\~a}o do pitch angle de um el{\'e}tron com
energia relativ{\'{\i}}stica em um campo magn{\'e}tico dipolar,
perturbado pela ocorr{\^e}ncia de ondas chorus. A
solu{\c{c}}{\~a}o da equa{\c{c}}{\~a}o do movimento foi obtida
numericamente. Em uma primeira etapa, realizou-se a
valida{\c{c}}{\~a}o do c{\'o}digo desenvolvido utilizando o
m{\'o}dulo Scipy de Python, comparando com os resultados obtidos
por Bortnik et al. (2008). Uma vez validado o c{\'o}digo, este
foi utilizado para calcular a varia{\c{c}}{\~a}o do pitch angle
do el{\'e}tron para a intera{\c{c}}{\~a}o
onda-part{\'{\i}}cula em um evento de perda de el{\'e}trons
ocorrido em 12 de setembro de 2014 (ALVES et al., 2016). Os dados
dos campos eletromagn{\'e}ticos da onda foram obtidos a partir
das sondas Van Allen Probes para el{\'e}trons de energia 2 e 5
MeV na zona equatorial e par{\^a}metro L = 5, 5 e 6. A
varia{\c{c}}{\~a}o do pitch angle {\'e} contabilizada
atrav{\'e}s do valor quadr{\'a}tico m{\'e}dio rms. Na
an{\'a}lise do evento obteve-se o menor valor de
[Delta][Alpha]rms = 0,25o, para dois casos diferentes quando L = 6
e L = 5,5, ambos com frequ{\^e}ncia de 1 kHz, energia de 5 MeV. O
valor m{\'a}ximo foi de [Delta][Alpha]rms = 0,44o para a onda de
0,5 kHz e o el{\'e}tron de 2 MeV posicionado inicialmente em L =
5,5. ABSTRACT: The Earths magnetic field varies depending on the
conditions of the magnetosphere, as well as on the dynamics of the
particles present in it. When charged particles are in the
magnetic field, they describe three main movements: gyro motion
around the field lines; bounce motion between the mirroring points
in the northern and southern hemispheres and drift motion around
the Earth, and each of these movements is associated with a
physical quantity called adiabatic invariant. If there is no
disturbance in the field, particles will remain trapped inside the
magnetosphere. However, in the presence of external disturbances,
there are certain limits at which adiabatic invariants are broken.
In this work, it is found that for particles with energies between
2 and 5 MeV with an initial position greater than 7RE there may be
loss of the particle, depending on its energy. Certain mechanisms
can generate particle loss, one of which is the interaction with
chorus waves. Chorus waves are a type of whistler waves with RCP
(Right-hand Circularly Polarized) polarization that propagate
parallel to the Earths magnetic field with frequencies between
hundreds of Hz to a few kHz. As they propagate, they can interact
with relativistic energetic electrons in the Van Allen radiation
belt. When the gyro-resonance condition is reached, the
interaction can cause electron loss. This work aims to evaluate
the pitch angle variation of an electron with relativistic energy
in a dipolar magnetic field, disturbed by the occurrence of chorus
waves. The motion equations solution is obtained numerically. In
the first step, the code developed using the Python Scipy module
was validated, comparing with the results obtained by (BORTNIK et
al., 2008). Once the code was validated, it was used to calculate
the electron pitch angle variation for the wave-particle
interaction in an electron loss event that occurred on September
12, 2014 (ALVES et al., 2016). The waves eletromagnetic fields
data were obtained from the Van Allen Probes for electrons
energies of 2 and 5 MeV in the equatorial zone and at L-shell
values of L = 5,5 and 6. The variation of the pitch angle is
accounted for by using the average square value of rms. In the
event analysis, the lowest value of [Delta][Alpha]rms = 0,25o was
obtained for two different cases when L = 6 and L = 5,5, both with
a frequency of 1 kHz, energy of 5 MeV. The maximum value of
[Delta][Alpha]rms was 0,44o for the wave with frequency 0,5 kHz
and for the 2 MeV electron initially positioned at L = 5,5.",
committee = "Alves, Maria Virg{\'{\i}}nia (presidente) and Alves,
L{\'{\i}}via Ribeiro (orientadora) and Silva Souza, Vitor Moura
Cardoso e and Lucas, Aline de",
englishtitle = "Movement of charged particles, with relativistic velocity, under
action of disturbed geomagnetic field",
language = "pt",
pages = "88",
ibi = "8JMKD3MGP3W34R/42EJHLP",
url = "http://urlib.net/ibi/8JMKD3MGP3W34R/42EJHLP",
targetfile = "publicacao.pdf",
urlaccessdate = "25 abr. 2024"
}