Research

Magnetic Materials

Energy Material Interaction in Extreme Environments

Engineering for Fusion Energy

(https://fei.ucsd.edu/)

Optical Materials, Lasers and Photonics

Ultrafast Laser Welding of Ceramics

While laser welding remains a cornerstone of modern manufacturing, its application to ceramics has historically been limited by thermal stress and subsequent material fracturing. To overcome this limitation, recent breakthroughs in ultrafast laser technology offer two innovative methods to join ceramics without the destructive high temperatures of traditional welding. The first technique strategically tunes the ceramic's intrinsic properties, enabling the laser to transmit through the bulk material and localize energy directly at the interface. The second technique optimizes a precise microscopic gap between the components to maximize energy deposition efficiency. Both approaches leverage incredibly short, high-energy pulses to induce a highly localized melt pool, offering a precise, thermal-shock-free alternative for advanced ceramic integration.

Penilla, E. H., et al. "Ultrafast laser welding of ceramics." Science 365.6455 (2019): 803-808. DOI: 10.1126/science.aaw6699

2019 — UC San Diego News: "Lasers enable engineers to weld ceramics"

Materials for Dynamics Ramp Compression

Materials with high-density gradients are desired for controlling loading paths in dynamic compression, important for studying material properties in extreme conditions and inertial confinement fusion. The large density difference between Al and W makes them ideal choices for producing gradient density materials, but their extremely different melting temperatures make them challenging to fabricate simultaneously. We report a method for producing Al–W porosity-free materials with a fourfold increase in density (2.7–11 g/cm3) across the composition range, from Al-rich to W-rich, without intermetallic phase formation.

Meisner, C. G., et al. "Al–W gradient density materials—Processing and dynamic ramp compression." Journal of Applied Physics 138.2 (2025). https://doi.org/10.1063/5.0261507

Materials for Fusion Energy

The development of fusion energy systems requires materials that can maintain performance under extreme heat fluxes, irradiation, rapid thermal cycling, and high-energy-density loading. Tungsten armor materials are critical for both ICF and MCF applications, where plasma-facing and target-facing components must resist melting, cracking, erosion, and microstructural damage during repeated fusion-relevant exposures. ICF capsule materials must also meet stringent requirements on density, composition, surface quality, and defect control in order to support symmetric implosions and efficient fuel compression. These coupled requirements make fusion materials design a challenging engineering research problem.

Target Tracking for Direct Drive IFE

The repetition rated approach to direct drive IFE requires a precise real-time target tracking system that is able to predict and focus the driver laser beams onto the center of the fuel target in order to create the fusion event. The target injection speed of 50-100m/s and the tracking accuracy of 20 microns make this a challenging engineering research problem.

Petzoldt, R., Alexander, N., Carlson, L., Flint, G., Goodin, D., Spalding, J., & Tillack, M. (2007). A Continuous, In-Chamber Target Tracking and Engagement Approach for Laser Fusion. Fusion Science and Technology, 52(3), 454–458. https://doi.org/10.13182/FST07-A1529

Optical and Laser Materials

In pursuit of superior properties for optical materials, such as toughness of extreme environment windows or thermal conductivity of laser gain media, processing techniques such as Current-Activated Pressure-Assisted Densification (CAPAD) allow for novel dopants and microstructures.

Penilla, E.H., Kodera, Y. and Garay, J.E. (2013), "Blue–Green Emission in Terbium-Doped Alumina (Tb:Al2O3) Transparent Ceramics." Adv. Funct. Mater., 23: 6036-6043. https://doi.org/10.1002/adfm.201300906

Penilla, E.H., Devia-Cruz, L.F., Duarte, M.A. et al. (2018), "Gain in polycrystalline Nd-doped alumina: leveraging length scales to create a new class of high-energy, short pulse, tunable laser materials." Light Sci Appl 7, 33 . https://doi.org/10.1038/s41377-018-0023-z

S.R. Casolco, J. Xu, J.E. Garay (2008) "Transparent/translucent polycrystalline nanostructured yttria stabilized zirconia with varying colors." Scripta Materialia, Volume 58, Issue 6, Pages 516-519, https://doi.org/10.1016/j.scriptamat.2007.11.014.

Laser-Material Interaction and Extreme Environments

Laser impulse experiments are relevant to many applications ranging from medical devices and manufacturing to fusion energy and high energy density physics. ICF studies at the National Ignition Facility (NIF) have shown pressures exceeding 100 billion atm and 100 million °C. Through collaboration with facility scale laser platforms such as NIF's Direct Laser Impulse (DLI), LLE Omega, and LLNL's Jupiter Laser Facility (JLF), we have conducted fundamental studies of relevant materials such as Titanium, Fused Silica, and LiF.

Magnetic Materials

CAPAD allows for the rapid prototyping and characterisation of novel magentic and optomagnetic materials.

S. Ramirez, K. Chan, R. Hernandez, E. Recinos, E. Hernandez, R. Salgado, A.G. Khitun, J.E. Garay, A.A. Balandin, (2017) "Thermal and magnetic properties of nanostructured densified ferrimagnetic composites with graphene - graphite fillers." Materials & Design, Volume 118, Pages 75-80, https://doi.org/10.1016/j.matdes.2017.01.018.

Chi Tang, Mohammed Aldosary, Zilong Jiang, Houchen Chang, Benjamin Madon, Kyle Chan, Mingzhong Wu, Javier E. Garay, Jing Shi (2016) "Exquisite growth control and magnetic properties of yttrium iron garnet thin films." Appl. Phys. Lett. 108 (10): 102403. https://doi.org/10.1063/1.4943210

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