Careers

Fellowship Experiences

Ethan Secor

Etjam Secor

2018 Truman Fellow

Ethan Secor received his PhD from Northwestern University in materials science and engineering in September 2017.  He earned his BS from Drake University, with a double major in chemistry and physics.  He has received several awards including a National Defense Science and Engineering Graduate Fellowship.  His graduate work on graphene inks resulted in a commercialization opportunity, two patents and several additional patent applications, and over 10 journal papers.

For his Truman Fellowship, “Nanomaterial Ink Development for Smart Manufacturing,” Ethan is designing a digital additive manufacturing platform for simultaneous codeposition of nanomaterial inks.  This could offer opportunities for bottom-up fabrication of functionally-graded materials, printing of chemically reactive or incompatible precursors, and in situ composite synthesis.  This project is enabled by novel additive manufacturing technologies developed at Sandia, along with the Labs' breadth of expertise in nanomaterial ink synthesis and processing.  By integrating automated characterization and feedback controls, this would attempt to change the paradigm for ink and material discovery using high throughput screening.  His work will have applications in Nuclear Deterrence and National Security Programs mission areas.  His mentor will be Bryan Kaehr (a former Truman Fellow) and manager Randy Schunk, Advanced Materials Laboratory, 1815.  Ethan began his Fellowship in October 2017.

Daniel Ruiz

Daniel Ruiz

2018 Truman Fellow

Daniel Ruiz received his PhD in plasma physics from Princeton University in August 2017.   Additionally, he has a MS degree in nuclear reactor physics from the Institut National des Sciences et Techniques Nucléaires in France and a BA degree in physics engineering from the Instituto Tecnológico de Monterrey in Mexico.  During his PhD studies, Daniel’s research was mainly focused on developing a new systematic approach based on variational principles to describe wave dynamics.  In particular, he extended and reformulated geometrical optics as a first-principle Lagrangian theory that correctly describes polarization effects, such as mode conversion and the polarization-driven bending of ray trajectories.  During the same period, he received two fellowships: the National Defense Science and Engineering Graduate Fellowship and the Presidential Fellowship from Princeton.  He is an author of 13 peer-reviewed publications and gave an invited talk at the 2016 APS Division of Plasma Physics Conference.

Daniel’s Truman Fellowship research will focus on developing a new theoretical model to better understand the basic physics of laser-plasma instabilities (LPI) processes relevant to the magnetized liner inertial fusion (MagLIF) experiment at Sandia.  In recent years, the MagLIF platform has become one of nation’s leading experiments in inertial confinement fusion.  In MagLIF, a pre-magnetized deuterium fuel is heated by a 2.5 KJ, 1 TW laser and is then magnetically imploded by a 19 MA, 100 ns rise-time current.  This unique experimental platform has achieved extreme fusion-relevant plasma conditions hard to reproduce elsewhere.  More excitingly, MagLIF still has room for improvement. Much work remains to be done to optimize the MagLIF laser-heating stage.  Current experiments suggest that only a fraction of the laser energy is transferred to the fuel in MagLIF, while the rest of the energy is lost.  The low-energy coupling is mainly due to the presence of LPI processes, for example laser scattering.  The development of a general understanding of LPI processes and the eventual leveraging of that understanding to optimize the MagLIF preheat is of central importance to the entire MagLIF campaign.

In his Truman work, Daniel’s research will mainly focus on developing an advanced Lagrangian theory to better describe laser scattering processes, such as stimulated Raman scattering and stimulated Brillouin scattering.  He plans to construct a model that incorporates fluid nonlinearities, trapped-particle effects, and wave-wave coupling.  Working with Sandia experts, he hopes to implement his models in Sandia’s high energy density physics codes that are presently used to design experiments on Z.  This simulation capability would be the first of its kind.  Daniel is conducting his research with the “Radiation and ICF Target Design” group (1684).  His mentor is Michael Glinsky, and his manager is Kyle Peterson.  Daniel began his fellowship in October 2017.

Yiyang Li

Yiyang Li

2018 Truman Fellow

Yiyang received his BS in Electrical and Computer Engineering from Olin College and his MS and PhD in Materials Science and Engineering from Stanford University.  His thesis worked used in situ characterization to understand ion insertion mechanisms in Li-ion batteries at the nanoscale, and has been published in journals including Science and Nature Materials.  For his work, he has been awarded the Gold Graduate Student Award by the Materials Research Society and the Young Investigator Award by the International Society for Solid State Ionics.  Yiyang also received the Walter J. Gores Award, Stanford University’s highest teaching award, for his role in teaching and mentoring.

Yiyang’s Truman Fellowship extends electrochemical ion insertion beyond energy conversion and storage by developing a new class of materials whose properties can be dynamically changed through electrochemistry.  Examples include transistors, optical resonators, and actuators.  He will focus on understanding the change in electronic and mechanical properties associated with ion insertion which can be harnessed in new smart devices.  He will also integrate these novel materials with micro fabrication techniques to create microscale devices.  The proposed work is aligned with Sandia’s research interests in smart materials.  Yiyang began his fellowship in August 2017, under the mentorship of Farid El Gabaly Marquez (8342) and managers, Christian Mailhiot and Zhiyong Li.