Sökning: "Sun: magnetic fields"

Visar resultat 1 - 5 av 28 avhandlingar innehållade orden Sun: magnetic fields.

  1. 1. Transformation Optics for Controlling DC Magnetic Field

    Författare :Fei Sun; Sailing He; Hao Yang; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Transformation magneto-statics; magnets; DC magnetic field; Electrical Engineering; Elektro- och systemteknik; Teknisk materialvetenskap; Materials Science and Engineering;

    Sammanfattning : Based on the form-invariant of Maxwell’s equations under coordinate transformations, we extend the theoryof transformation optics to transformation magneto-statics, which can design magnets through coordinatetransformations. Some novel DC magnetic field illusions created by magnets (e.g. LÄS MER

  3. 2. Formation of solar bipolar regions : Magnetic flux concentrations from suction of the negative effective magnetic pressure instability

    Författare :Illa Rivero Losada; Axel Brandenburg; Matthias Rempel; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetohydrodynamics MHD ; turbulence; dynamo; Sun: magnetic fields; Sun: rotation; Sun: activity; Sun: dynamo; Astronomy; astronomi;

    Sammanfattning : Sunspots stand out on the visible solar surface. They appear as dark structures evolving and changing over time. They host energetic and violent events, like coronal mass ejections and flares, and concentrate strong magnetic fields. LÄS MER

  4. 3. Constraining magnetic heating in the solar chromosphere

    Författare :Roberta Morosin; Jaime de la Cruz Rodríguez; Elena Khomenko; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; magnetic fields; spectropolarimetry; Astronomy; astronomi;

    Sammanfattning : The chromospheric and coronal heating problems remain one of the foremost open questions in solar and stellar physics: how are the outer layers of the Sun heated from a few thousand kelvin in the photosphere to the million-degree corona? Radiation alone is not capable of transporting the required energy to explain observations from the inner layers. Phenomena associated with the presence of magnetic fields could provide the missing energy. LÄS MER

  5. 4. Semiconductor Nanoelectronic Devices Based on Ballistic and Quantum Effects

    Författare :Jie Sun; Fasta tillståndets fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Semiconductor; Quantum Dots; Ballistic Transport; InGaAs InP 2DEG; Nanoelectronics;

    Sammanfattning : As current silicon-based microelectronic devices and circuits are approaching their fundamental limits, the research field of nanoelectronics is emerging worldwide. With this background, the present thesis focuses on semiconductor nanoelectronic devices based on ballistic and quantum effects. The main material studied was a modulation doped In0. LÄS MER

  7. 5. Investigating magnetic fields in the solar chromosphere

    Författare :Alexander Pietrow; Dan Kiselman; Jaime de la Cruz Rodr´ıguez; Oleg Kochukhov; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; chromosphere; plage; Astronomy; astronomi;

    Sammanfattning : Solar plage has been the topic of many studies since its initial description in the mid 19th century, but as of yet it has not been understood to the point where we can reproduce all aspects of these active regions in quasi-realistic numerical models. To a large extent, this is caused by an incomplete understanding of the magnetic structure that drives the activity in these areas. LÄS MER