“With a PhD dissertation, I believe a person should give something completely new to the world.” This is what drives Ashanthi Maxworth, PhD candidate in electrical engineering, who is working to develop a model to determine how electromagnetic waves, specifically whistler waves, are transmitted through the Earth’s magnetosphere. Determining the power-flow path of these waves is called ray tracing.
“Whistler waves were identified during World War I and are mainly created due to lightning strikes,” said Maxworth. “Whistler ray tracing has many practical applications in the areas of space weather, lightning research, space physics and communications. Understanding the physics of lightning requires advanced simulations.”
The model she is developing aims to advance that understanding; such models are frequently used for predicting space weather, launching satellites or predicting the impact of magnetospheric electromagnetic waves on the Earth’s atmosphere.
The magnetosphere and the ionosphere are found outside of the Earth’s atmosphere and are in a plasma state. In plasma, the fourth state of matter, everything exists in an ionized state, so when the whistler waves travel through the magnetosphere and ionosphere, they can interact with the ionized particles in the plasma. This is known as wave-particle interaction, and it often releases energy that may damage space electronics, damage communication links such as GPS communications, change the dynamics of the Earth’s radiation belts and significantly impact space weather.
“It is important to accurately predict the power-flow path of the whistler waves and minimize their undesirable effects,” said Maxworth, who works closely with associate professor of electrical engineering Mark Golkowski.
According to Maxworth, the current available methods trace the propagation of waves in cold plasma environments, in which the temperature and pressure are considered to be negligible. However, in actuality the sun heats the plasma, so she and Golkowski have extended their work into warm plasma environments, where variations in temperature and pressure play a significant role in how the waves behave.
“Warm plasma ray tracing is very complicated. No one has performed this research before, which is why Dr. Golkowski suggested working on it,” she said. “My hope is that our work will make the lives of future scientists much easier.”
Working with such a unique situation comes with its challenges. Maxworth is often asked how she can verify that her model is accurate. However, she is confident in her research and in the expertise provided by Golkowski and the other members of her PhD committee, and she continually strives to find ways to ensure the model’s accuracy. For example, earlier this year Golkowski presented at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, where he and Maxworth were able to obtain Van Allen probe satellite data relevant to their research. Maxworth currently is comparing those observations with the results from her model. “So far everything matches up,” she said.
Maxworth hopes to finish her dissertation in May 2017, after which she plans to remain in academia and continue to build research collaborations and gain experience. In the end, it all comes back to creating something useful for future scientists.
“I want to build an accurate model and give it to the science community so they can use it for their future research.”