COMPUTING SCIENCES AREA

A CONVERSATION WITH REVATHI JAMBUNATHAN

Revathi, also known as "Reva," is a postdoctoral researcher in the Center for Computational Sciences and Engineering (CCSE) in the Computational Research Division (CRD) of the Computing Sciences Area. As a high school student, she participated in a stargazing session on a camping trip. There, underneath the starry skies, she was smitten. She knew she wanted to do something in her career related to space. Today, she is excited to be pursuing her childhood dream.

What is your area of work?

I work in the field of computational plasma physics. Part of my research is to understand why pulsars emit light. In particular, I am trying to understand the mechanisms that accelerate charged particles in the region surrounding pulsars, called the magnetosphere, using computational methods.

What big challenges are you hoping to solve with your scientific research in the next 20 years?

Pulsars are neutron stars which are formed when massive stars 10-20 times the size of our sun, explode and then collapse into a star the size of a city. They are so dense that a teaspoon of one pulsar weighs as much as Mount Everest. They are also highly magnetized, and can spin 700 times in the blink of an eye, emitting twin beams of electromagnetic radiation, like a cosmic lighthouse. They are amazing interstellar objects and have been used to detect exoplanets and gravitational waves. They can also potentially be used for deep space navigation.

Ten years ago, scientists discovered that pulsars emit a large spectrum of radiation, from radio waves to gamma rays. This was very surprising; it showed that the charged particles get accelerated to a high energy very quickly, breaking down previous assumptions about the acceleration mechanisms. I’m performing simulations to understand what is accelerating these particles and what is driving these pulsar emissions with such an incredible range.

The research challenge is how to address such a large range of length scales. It’s as if you were trying to take a picture of Berkeley from the sky, and wanted to capture both the city and a lemon on a lemon tree in the city. It’s very difficult to capture both in the same photo. Today we have computational tools to view what’s going on with pulsars at the smaller scale, and also at the global scale, but not together. That’s what we’re aiming for in the long run, to create a tool that can capture and explore all these different scales at the same time. Capturing not just all the length scales but also the interactions between scales is crucial to our understanding of the pulsar emission. What we learn from these simulations regarding charged particle dynamics in extreme environments can also add to our understanding of current disruption in fusion devices and solar flares.

What steps are you taking today to accomplish this vision?

I’m contributing to the development of WarpX, which is an electromagnetic particle-in-cell code used to simulate high-energy plasma dynamics. Although the code was built primarily for modeling particle accelerator devices, it can also be leveraged to investigate particle acceleration in pulsar magnetospheres. WarpX can simulate both the small scale acceleration mechanism as well as the global dynamics of the radiation and pulsar spin down. Along with my colleagues in CCSE and ATAP (the Accelerator Technology and Applied Physics Division), I’m working on fine-grained simulations at the smaller scale, focusing on the areas where we think the acceleration is happening. I’m also working on simulations that explore pulsar magnetospheres at a global scale; investigating their composition, energy, electric, and magnetic fields. These are separate simulations now, but someday we hope to be able to link these and capture the different scales in the same simulation frame; in the same photo, if you will.

Who would you like to partner with at the Lab to bring this vision to life?

The Lab has such a great collaborative environment. In addition to working with members of CCSE and ATAP on developing WarpX, our team is also collaborating with scientists and engineers at NERSC.

We’re also now working to understand and to model the transmission of signals in circuits for next-generation microelectronic devices. It’s a very different area, but relies on the same equations—Maxwell’s equations—and also requires computational electrodynamics. We are working with the Molecular Foundry, which is providing material properties for our simulations of the new devices. We also collaborate with scientists at CRD and the Material Science Division who design and fabricate these devices on a larger scale. Our simulations will serve as a bridge between atomistic-scale material analysis and large-scale devices informing what material properties and circuit configurations are needed for a performant device. We started this project -- which we call ARTEMIS -- by adding relevant physics modules and coupling those with the Maxwell module already in WarpX. The new code will help us model and understand signal loss in a circuit.

Who from the past, present, or future would you like to collaborate with? And on what?

I’d like to chat with James Clerk Maxwell—his theory for electromagnetic radiation formed the core for understanding electromagnetic signals, whether in pulsars or microelectronic devices. I’d love to go back in time and meet with him. In the present, I would love to collaborate with researchers working on computational electrodynamics applied to astrophysical processes, particle accelerators, and microelectronic devices. All these topics are exciting for me. That being said, we don’t quite know what new exciting science will emerge and as part of CCSE and CRD at Berkeley Lab, I look forward to contributing wherever the new science will take us.

I would also like to contribute to diversity and inclusivity in science. I think the people working in science should be representative of the people who will benefit from it. The Lab has some great outreach programs for K-12 STEM, and I would love to support these efforts and communicate that science and math is fun.