We report on the first successful proof-of-principle experiment to manipulate laser-matter interactions on microscales using highly ordered Si microwire arrays. The interaction of a high-contrast short-pulse laser with a flat target via periodic Si microwires yields a substantial enhancement in both the total and cutoff energies of the produced electron beam. The self-generated electric and magnetic fields behave as an electromagnetic lens that confines and guides electrons between the microwires as they acquire relativistic energies via direct laser acceleration. DOI: 10.1103/PhysRevLett.116.085002 Laser-matter interactions at relativistic intensities have exhibited many interesting physical processes. These include the acceleration of electrons [1][2][3][4], protons, and heavy ions [5][6][7], the creation of electron-positron jets [8][9][10], and attosecond pulse generation [11,12]. The investigation of ultrashort pulse lasers interacting with initially soliddensity matter has been mainly focused on flat targets, with little or no control over the interaction. Recently the focus has shifted toward using advanced targets with the aim of increasing laser beam absorption and subsequent energy partition among various plasma species. Structured interfaces including nanoparticles [13], snowflakes [14], and nanospheres [15] have been reported to enhance laser absorption and proton acceleration, and the trapping of femtosecond laser pulses of relativistic intensity deep within ordered nanowires resulted in volumetric heating of dense matter into a new ultrahot plasma regime [16]. Another proposal addressed the potential for prescribing geometrical structures on the front of a target to greatly enhance the yield of high-energy electrons while simultaneously confining the emission to narrow angular cones [17].Microengineering laser plasma interactions, at intensities above the material damage threshold, has not been extensively explored. The main reason is that the amplified short pulses are inherently preceded by nanosecond-scale pedestals [18]. This departure from an ideal pulse can substantially modify or destroy any guiding features before the arrival of the intense portion of the pulse.Laser-pulse cleaning techniques are now being employed to significantly minimize unwanted prepulse and pedestals. For example, Ti:sapphire-based short-pulse high-intensity lasers routinely use a cross-polarized wave generation technique to achieve a contrast of at least 10 10 on the nanosecond time scale [19]. The manufacturing of advanced micro-and nanostructures has been the domain of specialized scientific disciplines such as nanoelectronics [20], microfluidics [21], and photovoltaics [22]. Microstructures with features as small as 200 nm can now be easily manufactured by nonexperts using commercially available 3D direct laser writing instruments [23]. Furthermore, 3D large-scale simulations with enough spatial and temporal resolution to capture the details of the interaction are now possible thanks to recent advances in massiv...
Efficient coupling of intense laser pulses to solid-density matter is critical to many applications including ion acceleration for cancer therapy. At relativistic intensities, the focus has been mainly on investigating various laser beams irradiating initially overdense flat interfaces with little or no control over the interaction. Here, we propose a novel approach that leverages recent advancements in 3D direct laser writing (DLW) of materials and high contrast lasers to manipulate the laser-matter interactions on the micro-scales. We demonstrate, via simulations, that usable intensities ≥1023 Wcm−2 could be achieved with current tabletop lasers coupled to micro-engineered plasma lenses. We show that these plasma optical elements act as a lens to focus laser light. These results open new paths to engineering light-matter interactions at ultra-relativistic intensities.
We present an experimental demonstration of the efficient acceleration of electrons beyond 60 MeV using micro-channel plasma targets. We employed a high-contrast, 2.5 J, 32 fs short pulse laser interacting with a 5 m inner diameter, 300 m long microchannel plasma target. The micro-channel was aligned to be collinear with the incident laser pulse, confining the majority of the laser energy within the channel. The measured electron spectrum showed a large increase of the cut-off energy and slope temperature when compared to that from a 2 m flat Copper target, with the cutoff energy enhanced by over 2.6 times and the total energy in electrons >5 MeV enhanced by over 10 times. Three-dimensional particle-in-cell simulations confirm efficient direct laser acceleration enabled by the novel structure as the dominant acceleration mechanism for the high energy electrons. The simulations further reveal the guiding effect of the channel that successfully explains preferential acceleration on the laser/channel axis observed in experiments. Finally, systematic simulations provide scalings for the energy and charge of the electron pulses. Our results show that the micro-channel plasma target is a promising electron source for applications such as ion acceleration, Bremsstrahlung X-ray radiation, and THZ generation.
High intensity laser-plasma interactions produce a wide array of energetic particles and beams with promising applications. Unfortunately, high repetition rate and high average power requirements for many applications are not satis ed by the lasers, optics, targets, and diagnostics currently employed. Here, we address the need for high repetition rate targets and optics through the use of liquids. A novel nozzle assembly is used to generate high-velocity, laminarowing liquid microjets which are compatible with a low-vacuum environment, generate li le to no debris, and exhibit precise positional and dimensional tolerances. Jets, droplets, submicron thick sheets, and other exotic con gurations are characterized with pump-probe shadowgraphy to evaluate their use as targets. To demonstrate a high repetition rate, consumable, liquid optical element, we present a plasma mirror created by a submicron thick liquid sheet. is plasma mirror provides etalon-like anti-re ection properties in the low-eld of 0.1% and high re ectivity as a plasma, 69%, at a repetition rate of 1 kHz. Practical considerations of uid compatibility, in-vacuum operation, and estimates of maximum repetition rate in excess of 10 kHz are addressed. e targets and optics presented here enable the use of relativistically intense lasers at high average power and make possible many long proposed applications. . All diode-pumped, highrepetition-rate advanced petawa laser system (hapls).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.