CAREER: Energetic Electron Trapping and Acceleration in Magnetized Plasma with Magnetic Islands and Field Stochasticity

This award supports a study of energetic electron acceleration and transport in magnetized plasmas in geospace and in a laboratory. Solar flares directed toward the Earth are known to cause massive radio outages, interference with GPS systems and aircraft communication, damage to spacecraft and to threaten astronauts’ safety. It has been shown that up to 50% of the energy released during solar flares can be carried by energetic electrons (EEs).

However, the mechanisms for the observed electron acceleration and transport remain unclear. This project will investigate how EEs get trapped, accelerated and de-trapped in magnetized plasmas with magnetic islands and stochastic fields both in space and in laboratory experiments. The scientific goals of the project will draw together the fields of space physics, solar physics, and plasma physics, while also connecting to the development of models for space weather prediction and fusion energy reactor disruption mitigation.

In addition, the project aims to establish the first plasma-focused professional development certification program in the state of Alabama, called “Gateway to Plasma”. The curriculum development includes writing an Introduction to Plasma textbook appropriate for students with little or no background in physics and mathematics. The content of the online lessons will be focused on plasma basics and teaching industry-relevant skills.

Observations suggest that energetic electrons can be trapped and accelerated in regions of the Earth’s magnetosphere where the magnetic field forms islands, or twisted magnetic flux tubes. It is hypothesized that when such islands merge or break apart, the EEs are de-confined through the formation of chaotic and random, or stochastic, magnetic fields.

This project will investigate the following specific questions: (i) What is the characteristic scale of islands needed to trap EEs? (ii) Can island contraction and expansion lead to diffusion regime switch? (iii) How do stochastic fields affect electron diffusion? (iv) How do changes in the disorder regime affect electron diffusion? (v) Which processes are universal and scalable from lab to space? These questions will be studied using a spectral approach where probability for transport in a given magnetic field topology is calculated from the energy spectrum of the corresponding Hamiltonian operator.

The spectral model will be informed from and validated against laboratory experiments, spacecraft measurements, and tracer particle simulations. This work is expected to advance knowledge relevant to space weather forecasting, as well as the operation and safety of future fusion energy reactors.

This project is jointly funded by the Division of Physics, the Established Program to Stimulate Competitive Research (EPSCoR), and the Division of Atmospheric and Geospace Sciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.