Physics Dept Seminar

January 16th, Wednesday (*SPECIAL DAY*)

Some Unresolved Problems of Physics of Ultra-Low-Frequency Waves in Space Plasma

Dr. Vyacheslav (Slava) A. Pilipenko

Inst. of Physics of Earth & Space Research Inst., Russia

(Terrestrial Physics, Host: Hyomin Kim)

Room: ECE 202

Time: 11:45 am - 12:45 pm with 11:30 am tea time

Ultra-low-frequency (< 10 Hz) electromagnetic waves in the space plasma have many similarities with ordinary waves around us. However, there is a branch of magnetohydrodynamic (MHD) waves – Alfven waves, that have very peculiar features: possibility to propagate at long distances along magnetic field lines without geometric attenuation, resonant mode coupling, etc. Moreover, ULF waves can effectively interact in a resonant way with energetic particles, resulting in energization of space plasma. Most of these features are well-known to space physicists and the relevant effects are observed on the ground and by satellites. However, some problems still remain to be resolved. Without complete understanding of these problem reasons, even seemingly, not fundamental, we cannot say with confidence that our knowledge about electromagnetic wave processes in space are correct.

Topics to be discussed are addressed to some unresolved problems of Ultra-Low-Frequency (ULF) observations at high latitude magnetometers in Arctic and Antarctica:

- Are non-conjugate resonant Alfven field line oscillations in open field line region (e.g., polar cap) possible?

- Do MHD surface oscillations of near-noon magnetopause exist? What is their ground signature?

- Where do monochromatic Pc3 waves in the polar cap (region of open field lines) come from? How does band-pass filtering of these signals occur at polar latitudes?

- Can Pc3 waves leak from dayside into the nightside magnetosphere? What is the mechanism?

- Are electromagnetic ion-cyclotron (EMIC) wave packets freely propagating or waveguide trapped in the magnetosphere? Do bouncing between conjugate ionospheres EMIC wave packets exist? Can EMIC waves be trapped in the magnetosphere?

- How strongly EMIC waves are modified upon transmission through the ionosphere to the ground?