Rubem Fonseca na França

Abstract

Agradeço a atenção, o tempo e o empenho de meus familiares, professores, amigos, colegas e novos conhecidos que aceitaram consagrar tempo e energia à coleta de dados, ao intercâmbio de informações e de idéias, contribuindo para a realização deste trabalho.

Magnetic Field Generation in Core-Sheath Jets via the Kinetic Kelvin-Helmholtz Instability

“…In this simulation study we use a core-sheath plasma jet structure instead of the counterstreaming plasma setups used in previous simulations by Alves et al (2012), Alves et al (2014), Grismeyer et al (2013a and Liang et al (2013a,b). The basic setup and illustrative results are shown in Figure 1.…”

“…Here the y-direction is infinite. Following Gruzinov (2008), Alves et al (2012), Alves et al (2014) and Grismayer et al (2013b) we assume uniform initial conditions on either side of the velocity shear surface, infinitely massive ions, and perturbations to the initial conditions of the following form:…”

“…Recently PIC simulations have been employed to study magnetic field generation and particle acceleration in velocity shears at the microscopic level using counterstreaming setups. Here the shear interactions are associated with the kinetic Kelvin-Helmholtz instability (kKHI), also referred to as the electron-scale Kelvin-Helmholtz instability (ESKHI), e.g., Alves et al 2012;Alves et al 2014;Grismayer et al 2013a,b;Liang et al 2013a,b). Alves et al (2012) found that alternating, hereafter AC, current and magnetic field modulations found in the non-relativistic regime are less noticeable in the relativistic regime because they are masked by strong and relatively steady, hereafter DC, current and associated magnetic field.…”

“…Among the three plasma types of relativistic shear flow, they have found that only the hybrid (e ± -i + ) plasma shear flow is able to energize the electrons to form a high-energy spectral peak plus a hard power law tail. Alves et al (2014) have extended the theoretical analysis and the simulations of the ESKHI to electron-ion plasmas with various density ratios across the shear surface, with a velocity shear gradient across the shear surface, and to warm as well as cold shear flows. For counter-streaming flows they find that unequal densities lead to "drift when the density symmetry is broken", the most rapid growth occurs for equal densities, that a velocity shear gradient slows the growth rate and, as in Grismayer el al.…”

Formação de Mestres e Doutores: exigências e competências

“…Por outras palavras, é expectável e desejável caminhar do conhecimento para o saber, sendo este convidado a anular-se e abrir-se a cada vez mais ao sabor. Como propõe Roland Barthes: Sapientia: nenhum poder, Um pouco de saber, O máximo de sabor... 27 Este desiderato vê fundamentada a sua legitimidade ao constatarmos, como Hegel, que as pessoas ficam sábias sempre que já é demasiado tarde. Talvez porque "vamos bordando a nossa vida, sem conhecer por inteiro o risco; representamos o nosso papel, sem conhecer por inteiro a peça.…”