arXiv subjects

Yung-Kun Liu

Publications and source records attributed to Yung-Kun Liu.

6 recordsLinked to original sources

arXiv2026

Magnetizing nonlinear plasma wakefields for positron acceleration

It is known that only a narrow plasma wakefield sliver in the electron-beam-driven blowout regime suits positron acceleration. Using 3D simulations, we show that matching the cyclotron frequency $ω_{c}$ with the plasma frequency $ω_{p}$ forms a stable electron column on axis, expanding the suitable phase space for positron acceleration sizably. For a plasma density $n_p = 10^{16}\text{ cm}^{-3}$ in a 35 T field, the interval expands 4.3 times, and a witness positron beam gains 100--150 MeV over 6 cm ($1.6$--$2.5$~GeV/m) with a 92\% capture rate.

physics.acc-ph↗

arXiv2026

A laser plasma soliton fusion scheme

We introduce a novel and generic fusion scheme enabled by laser-plasma solitons, which promises to overcome several fundamental obstructions to reaching the breakeven condition. To demonstrate that, we invoke both deuterium-tritium (DT) and proton-boron (pB) as fuels. The intense electromagnetic field trapped inside the soliton significantly enhances the DT and pB fusion cross sections. Its ponderomotive potential evacuates electrons almost instantly, while the ions left behind are accelerated by the unshielded Coulomb field to kinetic energies suitable for fusion reaction on a longer time scale. Such a difference in time scales renders a time window for fusion to occur efficiently in an electron-free environment. We inject two consecutive lasers, where the first would excite plasma solitons and the second, much more intense and with a matched lower frequency, would fortify the soliton electromagnetic field resonantly. Solitons are known to expand during its lifetime, which significantly increases the number of ions to participate in the fusion process and the ion propagation distance. We show that the breakeven condition is attainable for both DT and pB cases. Invoking fiber laser and the iCAN laser technologies for high repetition rate and high intensity operation, gigawatt output may be conceivable.

physics.plasm-ph↗

arXiv2025

Plasma wakefield: from accelerators to black holes

Commemorating the 2024 S. Chandrasekhar Prize, this review provides a retrospective on the genesis and evolution of plasma wakefield acceleration. It traces the journey from prehistory and the invention of the Plasma Wakefield Accelerator (PWFA), the establishment of its theoretical cornerstones, to its profound reverberations across fundamental physics, including astrophysics and analog gravity. The narrative emphasizes conceptual evolution, key theoretical breakthroughs, and future outlook, culminating in a vision for hybrid schemes and next-generation colliders. In addition to application to particle accelerators and high energy collider physics, it is found that plasma wakefield, with its ultra-intense acceleration, can also be applied to investigate gravity effects in the laboratory based on Einstein's equivalence principle. A specific example is accelerating flying relativistic plasma mirrors to investigate the celebrated black hole Hawking evaporation and the associated information loss paradox. We describe an ongoing experiment, AnaBHEL (Analog Black Hole Evaporation via Lasers), which aims at shedding some lights on the black hole information loss paradox.

physics.plasm-ph↗

arXiv2024

Characterization of Supersonic Jet and Shock Wave with High-Resolution Quantitative Schlieren Imaging

This paper presents an enhanced optical configuration for a single-pass quantitative Schlieren imaging system that achieves an optical resolution of approximately 4.6 micrometers. The modified setup decouples sensitivity from resolution, enabling independent optimization of these critical parameters. Using this high-resolution system, we conduct quantitative analyses of supersonic jets emitted from sub-millimeter nozzles into the atmosphere and investigate shock waves induced by knife blades interacting with these jets in a vacuum environment. The fine resolution allows for detailed visualization of shock wave structures and accurate measurement of density gradients. We demonstrate the system's effectiveness by examining the density gradient profile along the shock diamonds and mapping density profiles across shock waves. These density profiles are analyzed for their relevance in laser-plasma applications, including laser wakefield acceleration and the Analog Black Hole Evaporation via Laser (AnaBHEL) experiment. Our findings indicate that this system can help determine key parameters such as peak density, plateau length, and shock wave thickness-essential for optimizing electron acceleration and achieving specific plasma density profiles. This high-resolution quantitative Schlieren imaging technique thus serves as a valuable tool for exploring complex fluid dynamics and supporting advancements in laser-plasma physics research.

physics.optics↗

arXiv2022

AnaBHEL (Analog Black Hole Evaporation via Lasers) Experiment: Concept, Design, and Status

Accelerating relativistic mirror has long been recognized as a viable setting where the physics mimics that of black hole Hawking radiation. In 2017, Chen and Mourou proposed a novel method to realize such a system by traversing an ultra-intense laser through a plasma target with a decreasing density. An international AnaBHEL (Analog Black Hole Evaporation via Lasers) Collaboration has been formed with the objectives of observing the analog Hawking radiation and shedding light on the information loss paradox. To reach these goals, we plan to first verify the dynamics of the flying plasma mirror and to characterize the correspondence between the plasma density gradient and the trajectory of the accelerating plasma mirror. We will then attempt to detect the analog Hawking radiation photons and measure the entanglement between the Hawking photons and their "partner particles". In this paper, we describe our vision and strategy of AnaBHEL using the Apollon laser as a reference, and we report on the progress of our R&D of the key components in this experiment, including the supersonic gas jet with a graded density profile, and the superconducting nanowire single-photon Hawking detector. In parallel to these hardware efforts, we performed computer simulations to estimate the potential backgrounds, and derive analytic expressions for modifications to the blackbody spectrum of Hawking radiation for a perfectly reflecting, point mirror, due to the semit-ransparency and finite-size effects specific to flying plasma mirrors. Based on this more realistic radiation spectrum, we estimate the Hawking photon yield to guide the design of the AnaBHEL experiment, which appears to be achievable.

gr-qc↗

arXiv2020

Reflectivity and Spectrum of Relativistic Flying Plasma Mirrors

Flying plasma mirrors induced by intense lasers has been proposed as a promising way to generate few-cycle EUV or X-ray lasers. In addition, if such a relativistic plasma mirror can accelerate, then it would serve as an analog black hole to investigate the information loss paradox associated with the black hole Hawking evaporation. Among these applications, the reflectivity, which is usually frequency-dependent, would affect the outgoing photon spectrum and therefore impact on the analysis of the physics under investigation. In this paper, these two issues are investigated analytically and numerically with one-dimensional particle-in-cell (PIC) simulations. Based on our simulation results, we propose a new model that provides a better estimate of the reflectivity than those studied previously. Besides, we found that the peak frequency of the reflected spectrum of a gaussian incident wave deviates from the expected value, $4γ^2ω$, due to the dependence of reflectivity on the frequency of the incident wave.

physics.plasm-ph↗