Sökning: "cold plasma"

Visar resultat 1 - 5 av 75 avhandlingar innehållade orden cold plasma.

  1. 1. Rosetta Observations of Plasma and Dust at Comet 67P

    Författare :Fredrik Leffe Johansson; Anders Eriksson; Jan-Erik Wahlund; Nicolas André; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Rosetta; Comets; Plasma; Langmuir Probes; Dust; Spacecraft-plasma interaction; Electrostatic Probes; Rosetta; kometer; plasma; stoft; rymdfarkost-plasma växelverkan; Fysik med inriktning mot rymd- och plasmafysik; Physics with specialization in Space and Plasma Physics;

    Sammanfattning : In-situ observations of cometary plasma are not made because they are easy. The historic ESA Rosetta mission was launched in 2004 and traversed space for ten years before arriving at comet 67P/Churyumov-Gerasimenko, which it studied in unprecedented detail for two years. LÄS MER

  2. 2. Electrostatic plasma waves associated with collisionless magnetic reconnection : Spacecraft observations

    Författare :Konrad Steinvall; Yuri Khotyaintsev; Daniel Graham; Andris Vaivads; Jonathan Rae; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetic reconnection; Plasma waves; Electron holes; Solar wind; Magnetosphere; Magnetospheric Multiscale; Solar Orbiter; Fysik med inriktning mot rymd- och plasmafysik; Physics with specialization in Space and Plasma Physics;

    Sammanfattning : Magnetic reconnection is a fundamental plasma process where changes in magnetic field topology result in explosive energy conversion, plasma mixing, heating, and energization. In geospace, magnetic reconnection couples the Earth’s magnetosphere to the solar wind plasma, enabling plasma transport across the magnetopause. LÄS MER

  3. 3. Plasma environment of an intermediately active comet : Evolution and dynamics observed by ESA's Rosetta spacecraft at 67P/Churyumov-Gerasimenko

    Författare :Elias Odelstad; Anders Eriksson; Andrew Coates; Uppsala universitet; []
    Nyckelord :Rosetta; comet; 67P; RPC-LAP; RPC-MIP; RPC-ICA; RPC-MAG; ROSINA-COPS; Langmuir probe; spacecraft potential; plasma; Churyumov-Gerasimenko; ion composition analyzer; diamagnetic cavity; ion velocity; electron temperature; ion-neutral drag; collisional coupling; wake effects; filamentation; electron cooling; plasma waves; hybrid waves; Bernstein waves; minimum variance; polarization; wavelet; density fluctuations; magnetic field oscillations; drift-cyclotron instability; asymmetric plasma and magnetic field enhancements; Fysik med inriktning mot rymd- och plasmafysik; Physics with specialization in Space and Plasma Physics;

    Sammanfattning : The subject of this thesis is the evolution and dynamics of the plasma environment of a moderately active comet before, during and after its closest approach to the Sun. For over 2 years in 2014-2016, the European Space Agency’s Rosetta spacecraft followed the comet 67P/Churyumov-Gerasimenko at distances typically between a few tens and a few hundred kilometers from the nucleus, the longest and closest inspection of a comet ever made. LÄS MER

  4. 4. Ion escape from Mars : measurements in the present to understand the past

    Författare :Robin Ramstad; Stas Barabash; Yoshifumi Futaana; David Brain; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mars; escape; solar wind; evolution; CME; coupling; plasma; atmosphere; Space Physics; rymdfysik;

    Sammanfattning : Present-day Mars is a cold and dry planet with a thin CO2-dominated atmosphere comprising only a few ­­­mbar pressure at low altitudes. However, the Martian surface is marked with valley networks, hydrated mineral clays, carbonates and the remains of deltas and meandering rivers, i.e. LÄS MER

  5. 5. The importance of waves in space plasmas : Examples from the auroral region and the magnetopause

    Författare :Gabriella Stenberg; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; Plasma waves; magnetospheric physics; magnetopause; auroral region; wave distribution function; space exploration; reconnection; current tubes; Rymd- och plasmafysik; Space physics; Rymdfysik; rymdfysik; Space Physics;

    Sammanfattning : This thesis discusses the reasons for space exploration and space science. Space plasma physics is identified as an essential building block to understand the space environment and it is argued that observation and analysis of space plasma waves is an important approach.Space plasma waves are the main actors in many important processes. LÄS MER