Cold Plasma Seminars

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Each seminar in the series takes place at 12:00 – 13:00 pm Eastern Daylight Time (4-5 p.m. Universal Time Coordinated, 5-7 p.m. Central European Summer time)

Motivation

The Earth’s magnetosphere comprises multiple ion and electron populations with a broad range of energies, from the sub-eV particles of the ionosphere to the relativistic particles of the radiation belts. These diverse particle populations are co-located and interact through a variety of processes, including various plasma waves.

While the warm (ring current/plasma sheet) and hot (radiation belts) populations have received a lot of attention in part because of their potential harm to space infrastructure, the cold populations (with energy less than ~100 eV) are the least studied and in some cases have been referred to as the ‘hidden populations’. This is because spacecraft are typically charged to levels that make measuring the cold plasma properties very difficult and sometimes impossible. For electrons, an additional complication is that spacecraft surfaces exposed to sunlight and bombarded by energetic particles emit secondary electrons with energies comparable to those of the cold electrons of the environment that can completely dominate the detector measurement.

However, the cold plasma has a strong impact on many phenomena that are critical to the dynamics of the near-Earth environment, both locally and globally. Examples include

• the cold plasma being the source of hot magnetospheric plasma
• solar-wind/magnetosphere coupling
• tail reconnection and substorm dynamics
• wave-particle interaction physics,
• plasmasphere/plasmasheet interactions
• structuring of the pulsating aurora.

Given the sparsity of measurements and the generally poor understanding of the cold populations, it is plausible that other impacts not yet known might exist. In all, this leaves a major gap in our understanding of the magnetosphere-ionosphere system.