Solar Wind Electron Instabilities caused by Uneven Temperatures — Analyzed with ALPS

What is it about?

In space, many plasmas—like those in the solar wind—are extremely hot and thin, which makes them unstable and prone to generating waves and fluctuations on their own. Scientists have seen this kind of behavior directly using spacecraft measurements near Earth and other planets. One of the key reasons for these instabilities is that the temperatures of the particles can be different depending on their direction of motion—this is called temperature anisotropy. In our work, we focus on understanding how this temperature anisotropy causes instabilities in the electrons of the solar wind. There are two main groups of electrons: a cooler, more thermal “core” and a hotter, more energetic “halo.” We study how both of these groups contribute to different types of instabilities, including ones called whistler and firehose instabilities. To do this, we use a new way of describing the halo electrons that avoids certain mathematical problems found in older models. Since this new approach is too complex to solve with pen and paper, we use a powerful numerical tool called ALPS to simulate how the plasma behaves. This helps us better understand how energy and fluctuations move around in space plasmas—an important step in explaining the dynamics of the solar wind and space weather.

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