The oblique firehose instability in a bi-kappa magnetized plasma

In this work, we derive a dispersion equation that describes the excitation of the oblique (or Alfvén) firehose instability in a plasma that contains both electron and ion species modelled by bi-kappa velocity distribution functions. The equation is obtained with the assumptions of low-frequency waves and moderate to large values of the parallel (respective to the ambient magnetic field) plasma beta parameter, but it is valid for any direction of propagation and for any value of the particle gyroradius (or Larmor radius). Considering values for the physical parameters typical to those found in the solar wind, some solutions of the dispersion equation, corresponding to the unstable mode, are presented. In order to implement the dispersion solver, several new mathematical properties of the special functions occurring in a kappa plasma are derived and included. The results presented here suggest that the superthermal characteristic of the distribution functions leads to reductions to both the maximum growth rate of the instability and of the spectral range of its occurrence

The general dielectric tensor for bi-kappa magnetized plasmas

In this paper, we derive the dielectric tensor for a plasma containing particles described by an anisotropic superthermal (bi-kappa) velocity distribution function. The tensor components are written in terms of the two-variables kappa plasma special functions, recently defined by Gaelzer and Ziebell [Phys. Plasmas 23, 022110 (2016)]. We also obtain various new mathematical properties for these functions, which are useful for the analytical treatment, numerical implementation, and evaluation of the functions and, consequently, of the dielectric tensor. The formalism developed here and in the previous paper provides a mathematical framework for the study of electromagnetic waves propagating at arbitrary angles and polarizations in a superthermal plasma

Produção de jogos digitais nos Institutos Federais: uma análise das possibilidades e potencialidades

Este artigo apresenta uma propostapara ampliara participaçãodos estudantes do ensinomédio técnico noprocesso de desenvolvimentos de jogos digitais educativos paraa aprendizagem móvel. Essesesforços encontram suporte nas dificuldades em integrar conhecimentos, quesão inerentes àprogramação, ao design e aos propósitos pedagógicos, enquanto possibilidades sãobuscadas para otimizar recursos humanos e financeiros. Considerandoque os primeiros passos já foramdados, pretende-seaumentar a produção dessas ferramentas em instituições federais de educação profissional e tecnológica.This article aims to foster the participation of technical high school students inthe process of developing digital educational games for mobile learning. These efforts find support in the difficulties in integratingknowledges, which are inherent to programming, design and pedagogical purposes, meanwhile possibilities are sought foroptimizing human and financial resources. Considering that the first steps have already beentaken, it is intended to enlarge the production of these tools (applets) in professional and technological education in federal institutions

LANÇAMENTO HORIZONTAL COM REALIDADE VIRTUAL: JOGO EDUCATIVO PARA SMARTPHONES DESENVOLVIDO POR ESTUDANTES DA EDUCAÇÃO PROFISSIONAL

:  Neste trabalho mostraremos um objeto virtual de aprendizagem desenvolvido por um grupo de estudantes do curso técnico em informática integrado ao ensino médio do Instituto Federal Sul-rio-grandense – Campus Bagé. Trata-se de um jogo de lançamento horizontal de projéteis direcionado para o ensino de física, cujo processo de modelagem é descrito e ilustrado visando contemplar as pesquisas iniciais, escolha de layout e interface, detalhes da jogabilidade em dispositivo portátil e os diferenciais do uso dos óculos de realidade virtual. Considerando que um dos propósitos do nosso projeto de pesquisa[1] é analisar a viabilidade da produção de jogos digitais pelos alunos da educação profissionalizante, e diante do indicativo de potencial pouco explorado que pode confrontar algumas das principais problemáticas associadas à incorporação das tecnologias móveis na educação básica, os resultados apontam que devemos continuar fomentando o talento dos jovens desenvolvedores da área de informática.[1] Projeto de pesquisa intitulado Análise e Desenvolvimento de Jogos Digitais para a Educação em Ciências, registrado na Pró-reitoria de Pesquisa, Inovação e Pós-graduação do IFSul sob o número PE02160816/124

Propagation and amplification of electromagnetic waves in superthermal magnetized plasmas

A anisotropia de temperatura de elétrons e íons no Vento Solar é um fenômeno que evidencia o papel de processos não térmicos que ocorrem no sistema Sol-Vento-Solar-Magnetosfera Terrestre (SVSM). Distribuições com dispersões de velocidade distintas, nas direções paralela e perpendicular ao campo magnético ambiente, possuem energia livre disponível para gerar instabilidades, as quais irão transferir parte desta energia livre para ondas, relaxando desta forma a distribuição em sentido ao equilíbrio termodinâmico. A fim de investigar as condições marginais de instabilidade, os modelos de funções de distribuição de velocidade supertérmicas com anisotropia de temperatura mais empregados na literatura e que são baseados num comportamento tipo lei de potência, são a distribuição bi-kappa (BK) e a distribuição produto-bi-kappa (PBK). Do ponto de vista puramente matemático, o cálculo do tensor dielétrico é mais simples com a distribuição PBK; isto porque esta já possui as dependências em v? e vk fatoradas, simplificando o cálculo das integrais ressonantes, a exemplo do que ocorre com a distribuição bi-Maxwelliana (BM). No presente trabalho desenvolvemos um formalismo matemático geral que permite a descrição analítica dos mais diversos fenômenos presentes em plasmas supertérmicos descritos por distribuições bi-kappa. Aplicamos este formalismo matemático na descrição da propagação e amplificação/absorção de ondas eletromagnéticas/eletrostáticas em plasmas supertérmicos e na presença de anisotropia de temperatura.The temperature anisotropy of electrons and ions in the Solar Wind is a phenomenon that highlights the role of non-thermal processes occurring in the Sun-Solar Wind-Terrestrial Magnetosphere system (SSVM). Distributions with distinct velocity dispersions, both in the parallel and perpendicular directions relative to the ambient magnetic field, have free energy available to generate instabilities, which will transfer part of the free energy into waves, thereby relaxing the distribution towards the thermodynamic equilibrium. In order to investigate the marginal conditions for instability, the models of superthermal velocity distribution functions more frequently employed in the literature, which feature a powerlaw dependence on the high-energy particles, are the bi-kappa (BK) and product-bi-kappa (PBK) distributions. From a purely mathematical point of view, the calculation of the dielectric tensor is simpler with the PBK distribution, since its dependence on the v? and vk velocity components is already factored, similar to what occurs with a bi-Maxwellian (BM) distribution. In this work we develop a general mathematical formalism that provides the analytical description of various phenomena present in superthermal plasmas described by bi-kappa distribution functions. We apply this mathematical formalism to the study of the propagation and amplification/damping of electromagnetic/electrostatic waves in superthermal plasmas and in the presence of temperature anisotropy

The oblique firehose instability in a bi-kappa magnetized plasma

In this work, we derive a dispersion equation that describes the excitation of the oblique (or Alfvén) firehose instability in a plasma that contains both electron and ion species modelled by bi-kappa velocity distribution functions. The equation is obtained with the assumptions of low-frequency waves and moderate to large values of the parallel (respective to the ambient magnetic field) plasma beta parameter, but it is valid for any direction of propagation and for any value of the particle gyroradius (or Larmor radius). Considering values for the physical parameters typical to those found in the solar wind, some solutions of the dispersion equation, corresponding to the unstable mode, are presented. In order to implement the dispersion solver, several new mathematical properties of the special functions occurring in a kappa plasma are derived and included. The results presented here suggest that the superthermal characteristic of the distribution functions leads to reductions to both the maximum growth rate of the instability and of the spectral range of its occurrence

Non-linear QCD dynamics and exclusive production in ep collisions

The exclusive processes in electron–proton (ep) interactions are an important tool to investigate the QCD dynamics at high energies as they are in general driven by the gluon content of proton which is strongly subject to parton saturation effects. In this paper we compute the cross sections for the exclusive vector meson production as well as the deeply virtual Compton scattering (DVCS) relying on the color dipole approach and considering the numerical solution of the Balitsky–Kovchegov equation including running coupling corrections. We show that the small-x evolution given by this evolution equation is able to describe the DESY-HERA data and is relevant for the physics of the exclusive observables in future electron–proton colliders and in photoproduction processes to be measured in coherent interactions at the LHC