Engineering topics

Milchberg, H. M.

Publications and source records attributed to Milchberg, H. M..

4 records

DOE OSTI2024

Self-Focused Pulse Propagation Is Mediated by Spatiotemporal Optical Vortices

We show that the dynamics of high-intensity laser pulses undergoing self-focused propagation in a nonlinear medium can be understood in terms of the topological constraints imposed by the formation and evolution of spatiotemporal optical vortices (STOVs). STOVs are born from point phase defects on the sides of the pulse nucleated by spatiotemporal phase shear. These defects grow into closed loops of spatiotemporal vorticity that initially exclude the pulse propagation axis, but then reconnect to form a pair of toroidal vortex rings that wrap around it. STOVs constrain the intrapulse flow of electromagnetic energy, controlling the focusing-defocusing cycles and pulse splitting inherent to nonlinear pulse propagation. Here, we illustrate this in two widely studied but very different regimes, relativistic self-focusing in plasma and nonrelativistic self-focusing in gas, demonstrating that STOVs mediate nonlinear propagation irrespective of the detailed physics.

42 ENGINEERING↗

DOE OSTI2024

Guided Mode Evolution and Ionization Injection in Meter-Scale Multi-GeV Laser Wakefield Accelerators

Here, we show that multi-GeV laser wakefield electron accelerators in meter-scale, low density hydrodynamic plasma waveguides operate in a new nonlinear propagation regime dominated by sustained beating of lowest order modes of the ponderomotively modified channel; this occurs whether or not the injected pulse is linearly matched to the guide. For a continuously doped gas jet, this emergent mode beating effect leads to axially modulated enhancement of ionization injection and a multi-GeV energy spectrum of multiple quasimonoenergetic peaks; the same process in a locally doped jet produces single multi-GeV peaks with <10% energy spread. A three-stage model of drive laser pulse evolution and ionization injection characterizes the beating effect and explains our experimental results.

43 PARTICLE ACCELERATORS↗

DOE OSTI2023

Linear colliders based on laser-plasma accelerators

Laser-plasma accelerators are capable of sustaining accelerating fields of 10–100 GeV/m, 100–1000 times that of conventional technology and the highest fields produced by any of the widely researched advanced accelerator concepts. Laser-plasma accelerators also intrinsically accelerate short particle bunches, several orders of magnitude shorter than that of conventional technology, which leads to reductions in beamstrahlung and, hence, savings in the overall power consumption to reach a desired luminosity. These properties make laser-plasma accelerators a promising accelerator technology for a more compact, less expensive high-energy linear collider providing multi-TeV polarized leptons. In this submission to the Snowmass 2021 Accelerator Frontier, we discuss the motivation for a laser-plasma-accelerator-based linear collider, the status of the field, and potential linear collider concepts up to 15 TeV. Herein, we outline the research and development path toward a collider based on laser-plasma accelerator technology, and highlight near-term and mid-term applications of this technology on the collider development path. The required experimental facilities to carry out this research are described. We conclude with community recommendations developed during Snowmass.

43 PARTICLE ACCELERATORS↗

DOE OSTI2023

Atmospheric effects on the laser-driven avalanche-based remote detection of radiation

Here, the effect of realistic atmospheric conditions on mid-IR (λ = 3.9 µm) and long-wave-IR (λ = 10 µm) laser-induced avalanche breakdown for the remote detection of radioactive material is examined experimentally and with propagation simulations. Our short-range in-lab mid-IR laser experiments show a correlation between increasing turbulence level and a reduced number of breakdown sites associated with a reduction in the portion of the focal volume above the breakdown threshold. Simulations of propagation through turbulence are in excellent agreement with these measurements and provide code validation. We then simulate propagation through realistic atmospheric turbulence over a long range (0.1–1 km) in the long-wave-IR regime (λ = 10 µm). The avalanche threshold focal volume is found to be robust even in the presence of strong turbulence, only dropping by ~50% over a propagation length of ~0.6 km. We also experimentally assess the impact of aerosols on avalanche-based detection, finding that, while background counts increase, a useful signal is extractable even at aerosol concentrations 10 5 times greater than what is typically observed in atmospheric conditions. Our results show promise for the long-range detection of radioactive sources under realistic atmospheric conditions.

54 ENVIRONMENTAL SCIENCES↗