Oct. 21, 2024
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Three Lab Scientists Named 2024 APS Fellows

By Patricia Brady,[email protected],(925) 423-4332

LLNL scientists Daniel Casey, Daniel Clark, and Raymond Smith have been named 2024 American Physical Society (APS) Fellows.

Casey was selected for “outstanding contributions to the understanding of the stagnation conditions required to achieve ignition.

Clark was honored for “extensive contributions to inertial confinement fusion state-of-the-art implosion modeling, innovative ignition designs, novel applications of laser-plasma interactions, and the scientific understanding of hydrodynamic instabilities.”

Smith was selected for “for pioneering dynamic ramp-compression experiments on high-energy laser facilities, resulting in significant discoveries in high-pressure materials physics and planetary science.”

The APS Fellowship Program was created to recognize members who may have made advances in physics through original research and publication or made significant innovative contributions in the application of physics to science and technology. They also may have made significant contributions to the teaching of physics or service and participation in the activities of the society.

Fellowship is a distinct honor signifying recognition by one’s professional peers. Each year, no more than one half of one percent of the society’s membership (excluding student members) is recognized by their peers for election to the status of fellow of the American Physical Society.

Daniel Casey: Experimental Excellence in Fusion Research

Daniel Casey is a physicist who works in the NIF&PS Directorate and is the low mode working group lead for the Inertial Confinement Fusion (ICF) program. He was recently appointed group leader for the Implosions & Stagnations Hydrodynamics) group. His work focuses on diagnosing and assessing the impact of asymmetries in ICF implosions.

“I am humbled and incredibly honored to be named an APS Fellow,” he said. “It is often said that scientists stand on the shoulders of giants. Indeed, I am indebted to my friends and colleagues who have helped me at every stage of my research and am deeply grateful.”

In ICF implosions, features that start as small imperfections become serious problems when they grow during the implosion.

 “We are now at the point where a 0.2 percent asymmetry in capsule thickness from one side to the other can manifest into a significant asymmetry. Imagine you have two stacks of paper 1,000 sheets high, but one stack is only a couple sheets of thinner. That’s the kind of imperfection we are worried about,” Casey said.

Casey is also leading a project to understand the degradations of implosions for inertial fusion energy (IFE) as a part of a Department of Energy Office of Science Early Career Research Program grant.

Right now, we’re getting energy gains greater than one on NIF,” Casey said, “but there is so much more work to do to understand these conditions, the limitations, and to push implosions to greater gains still.”

Daniel Clark: Leading the Charge in ICF Design and Modeling

Daniel Clark is a physicist who works in the Strategic Deterrence (SD) Directorate at LLNL and specializes in ICF design and modeling. He has served as the design lead for several experimental campaigns at NIF and, from 2013 to 2021, led the capsule modeling working group within the ICF program.

“To join so many of my exceptional colleagues in the ICF program in receiving the APS Fellowship is a profound honor,” Clark said. “The recognition not only acknowledges my individual contributions to the field but also highlights the Laboratory’s collaborative efforts. This honor inspires me to continue our pursuit of groundbreaking advancements in plasma physics.” 

Clark has been deeply involved in modeling, understanding, and designing ICF implosions at NIF for nearly two decades. His work focuses on understanding the hydrodynamic stability of implosions, which is crucial for achieving the high densities and temperatures necessary for ignition.

“We wandered in the darkness for several years on NIF, trying to understand why the implosions didn't behave the way simulations predicted,” Clark said. “Ultimately, a combination of modeling, basic theory, experimental measurements, and intuition formed our collective understanding and advanced our mission.”

This comprehensive understanding of how hydrodynamic instabilities degrade implosions has been instrumental in devising better designs that are more stable and capable of achieving higher yields. Clark’s work with the capsule modeling working group was significant in unraveling the mysteries behind the lower-than-expected yields in early NIF experiments.

From 2011 onwards, the group invested heavily in sophisticated and detailed models of NIF implosions. This culminated in state-of-the-art, fully three-dimensional implosion models that were at the cutting edge of computational capabilities at the time. Currently, Clark is leading a campaign alongside Casey, where they aim to produce designs with higher compression and stability.

Reflecting on the significance of reaching ignition, Clark emphasized the collective effort spanning decades and involving thousands of scientists and engineers.

“To be there at the moment when it actually happened is a rare privilege,” he said. “The tremendous pressures, densities, and temperatures we achieve inside a NIF implosion are mind-boggling, comparable to conditions found in the cores of stars.”

Raymond Smith: Pioneering Dynamic Ramp-Compression Techniques

Raymond Smith is a physicist who works in the Physical and Life Sciences Directorate and is the lead principal investigator for the NIF TARDIS X-ray diffraction platform, which has provided direct measurements of crystal structure and microstructural texture at terapascal (TPa) pressures (1 TPa is equivalent to 10 million Earth atmospheres).

“I’m honored to be selected as an APS Fellow, and I deeply appreciate this recognition from the American Physical Society,” Smith said. “This distinction reflects the collaborative efforts of my colleagues, mentors, and students who have contributed to my research journey. It motivates me to continue pushing the boundaries of scientific discovery and to foster a spirit of curiosity and innovation within the broader physics community.”

An expert in high-power laser systems, Smith led the development of laser ramp-compression techniques to measure isentropes (constant-entropy processes) in materials cold-compressed to multi-TPa pressures.

Ramp compression experiments apply a carefully tailored laser pulse shape that compresses material more softly without forming a shock. This technique helps scientists better understand the physics of solids compressed to extreme densities under a wider range of pressures and much lower temperatures.

He also built 1D and 2D imaging velocimetry systems on the Lab’s Jupiter Laser Facility to diagnose heterogeneous deformation, such as orientation-dependent brittle failure under dynamic compression. His experimental work on NIF and other laser facilitates has produced many high-profile publications including cover articles in Nature and Nature Astronomy.

For more information about all this year’s fellows, go to the APS site.

More Information:

“Two LLNL scientists selected as 2022 APS fellows,” LLNL News, October 19. 2022

“NIF Physicist Among Four LLNL Scientists Honored as APS Fellows,” NIF & Photon Science News, October 21, 2020

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