Physics & Astronomy Community Excellence: Structured Near-Peer Mentorship in Doctoral Degree Programs

Astronomy Education Journal · 2026-04-02

We have developed a near-peer mentorship program in the Department of Physics and Astronomy at the University of California, Irvine. The Physics and Astronomy Community Excellence (PACE) program is a graduate student led initiative designed to acclimate students and foster community through structured near-peer mentorship. Established in 2018, PACE provides guidance on academic resources, mental health, and various aspects of the graduate experience. Survey data indicates that PACE has had strong positive impacts on participants. Mentors, including those from historically underrepresented groups, report benefits including increased leadership skills, sense of belonging, and motivations for continuing in the field.

Implementing Bayesian optimization to compare injection regimes and pulse propagation in two stage LWFA

New Journal of Physics · 2025-11-25 · 1 citations

Abstract Predicting the properties of electrons accelerated to relativistic energies via laser wakefield acceleration is dependent on a wide range of parameters that are difficult to efficiently optimize. Such problems would benefit from the use of Bayesian optimization schemes, which if implemented correctly may efficiently find optimums in complex parameter spaces. By separating the laser wakefield mechanism into two stages, an initially higher density plasma of high Z gases may be used to inject higher charge while a low density homogeneous plasma can be used to efficiently accelerate electrons with the same laser pulse. However, the nonlinear relationship between the two stages makes the determination of optimal beam parameters difficult. We show that through the use of a Bayesian optimization process on 2.5D3V particle-in-cell simulations we are able to efficiently map out regions of interest across a wide variety of physical regimes while keeping down the computational costs of the parameter scan. Numerically modeling the two stage system, we varied the injection stage density profile and length and examined the impact on electron beam charge, energy spectrum, and emittance. We also examined the impact on the laser pulse itself with regards to the temporal pulse duration. Our analysis identified specific regions in the parameter space where variations in pulse propagation and injection processes significantly influenced the characteristics of the resulting electron beam. This approach enabled us to efficiently identify numerous physical regimes with options on how to tune the electron beam for various applications.

Broadband spatiotemporal light springs at relativistic intensities

Research Square · 2025-09-11

Phase matching in vector beam-driven high-harmonic generation with 3D-printed gas cells

Journal of the Optical Society of America B · 2025-10-27 · 1 citations

We present experimental results of high-harmonic generation (HHG) driven by a 1300 nm beam in three different polarization states: linear, radial, and azimuthal. We found that the optimal pressure for phase matching was roughly twice as high for the vector beam drivers than the linear driver. We attribute this difference in pressure primarily to the Gouy phase, which differs by a factor of two between the linear and vector polarization states. We demonstrate a target for HHG that produces a uniform pressure profile in the interaction region that is nearly identical to the backing pressure and preserves the mode of the driving beam. We provide characterization and validation of this technique through flow simulations and experimental measurements.

High-energy X-ray radiography with apodized petawatt laser beams

Optics Express · 2025-10-09 · 2 citations

We have produced laser wakefield-accelerated electron beams with energies of 2 GeV in Target Area 1 of the ZEUS facility. These electron beams oscillate in the accelerating structure that is produced in the wake of an ultrashort laser pulse (25 fs). These 'betatron' oscillations result in the emission of a collimated (4 mrad divergence) beam of high-energy X-ray/gamma photons (on the order of several hundred keV). In this work, we demonstrate the capabilities of the ZEUS laser system by showing that apodizing the laser beam in the near field allows for the production of high-quality betatron X-rays for radiography purposes. This demonstrates that a high-power, large-aperture laser beam could be split into multiple parts to drive betatron X-ray sources from multiple angles or temporal delays into a High Energy Density (HED) target to be probed, enabling pump-probe measurements at multiple temporal delays or tomography on a single shot.

Spatiotemporal shaping of broadband helical light pulses at relativistic intensities

ArXiv.org · 2025-08-08

Spatiotemporal control of laser pulses at relativistic intensities is a longstanding goal with broad implications in laser-plasma acceleration, high-brightness radiation sources, and extreme-field science. Laser pulses with helical spatiotemporal intensity profiles, often referred to as light springs, carry multiple spectral and orbital angular momentum (OAM) modes, producing a rotating intensity profile capable of coupling directly to helical plasma waves. Until now, light springs have only been realized on low-power systems, limited by optical damage thresholds and large-aperture beamline constraints. Here, we report the first experimental realization of light springs at relativistic intensities, achieving peak intensities above $1.4\times10^{18}$ W/cm$^{2}$. Our approach spectrally splits a high-power laser pulse, imprints distinct helical phases on each component, and coherently recombines them. Hyperspectral imaging, off-axis holography, and spectral phase reconstruction confirm excellent agreement with theory and reveal the potential to drive superluminal rotational velocities. Introducing spectral chirp demonstrates further control of the temporal evolution of the transverse mode structure. This platform opens new regimes of ultra-intense laser-plasma interaction where laser OAM can directly couple to plasma OAM.

Phase matching in Vector Beam Driven High Harmonic Generation with 3D-printed Gas Cells

ArXiv.org · 2025-09-19

We present experimental results of high harmonic generation(HHG) driven by a 1300 nm beam in three different polarization states: linear, radial, and azimuthal. We found that the optimal pressure for phasematching was roughly twice as high for the vector beam drivers than the linear driver. We attribute this difference in pressure primarily to the Gouy phase, which differs by a factor of two between the linear and vector polarization states. We demonstrate a target for HHG that produces a uniform pressure profile in the interaction region that is nearly identical to the backing pressure, and preserves the mode of the driving beam. We provide characterization and validation of this technique through flow simulations and experimental measurements.

Roadmap on basic research needs for laser technology

Journal of Optics · 2024-10-08 · 13 citations

Abstract Motivated by the profound impact of laser technology on science, arising from an increase in focused light intensity by seven orders of magnitude and flashes so short electron motion is visible, this roadmap outlines the paths forward in laser technology to enable the next generation of science and applications. Despite remarkable progress, the field confronts challenges in developing compact, high-power sources, enhancing scalability and efficiency, and ensuring safety standards. Future research endeavors aim to revolutionize laser power, energy, repetition rate and precision control; to transform mid-infrared sources; to revolutionize approaches to field control and frequency conversion. These require reinvention of materials and optics to enable intense laser science and interdisciplinary collaboration. The roadmap underscores the dynamic nature of laser technology and its potential to address global challenges, propelling progress and fostering sustainable development. Ultimately, advancements in laser technology hold promise to revolutionize myriad applications, heralding a future defined by innovation, efficiency, and sustainability.

Workforce Development Through Research-Based, Plasma-Focused Activities

arXiv (Cornell University) · 2023-03-11

This report is a summary of the mini-conference Workforce Development Through Research-Based, Plasma-Focused Science Education and Public Engagement held during the 2022 American Physical Society Division of Plasma Physics (APS DPP) annual meeting. The motivation for organizing this mini-conference originates from recent studies and community-based reports highlighting important issues with the current state of the plasma workforce. Here we summarize the main findings presented in the two speaker sessions of the mini-conference, the challenges and recommendations identified in the discussion sessions, and the results from a post-conference survey. We further provide information on initiatives and studies presented at the mini-conference, along with references to further resources.

Summary report from the mini-conference on workforce development through research-based, plasma-focused activities

Physics of Plasmas · 2023-06-01 · 1 citations

This report is a summary of the mini-conference on Workforce Development Through Research-Based, Plasma-Focused Science Education and Public Engagement held during the 2022 American Physical Society Division of Plasma Physics annual meeting. The motivation for organizing this mini-conference originates from recent studies and community-based reports highlighting important issues with the current state of the plasma workforce. Here, we summarize the main findings presented in the two speaker sessions of the mini-conference, the challenges, and recommendations identified in the discussion sessions and the results from a post-conference survey. We further provide information on initiatives and studies presented at the mini-conference, along with references to further resources.