Enhanced laser-driven proton acceleration using nanowire targets

AbstractLaser-driven proton acceleration is a growing field of interest in the high-power laser community. One of the big challenges related to the most routinely used laser-driven ion acceleration mechanism, Target-Normal Sheath Acceleration (TNSA), is to enhance the laser-to-proton energy transfer such as to maximize the proton kinetic energy and number. A way to achieve this is using nanostructured target surfaces in the laser-matter interaction. In this paper, we show that nanowire structures can increase the maximum proton energy by a factor of two, triple the proton temperature and boost the proton numbers, in a campaign performed on the ultra-high contrast 10 TW laser at the Lund Laser Center (LLC). The optimal nanowire length, generating maximum proton energies around 6 MeV, is around 1–2 $$\upmu$$ μ m. This nanowire length is sufficient to form well-defined highly-absorptive NW forests and short enough to minimize the energy loss of hot electrons going through the target bulk. Results are further supported by Particle-In-Cell simulations. Systematically analyzing nanowire length, diameter and gap size, we examine the underlying physical mechanisms that are provoking the enhancement of the longitudinal accelerating electric field. The parameter scan analysis shows that optimizing the spatial gap between the nanowires leads to larger enhancement than by the nanowire diameter and length, through increased electron heating.

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Improvement of proton energy in high-intensity laser-nanobrush target interactions

Laser and Particle Beams ◽

10.1017/s0263034612000134 ◽

2012 ◽

Vol 30 (2) ◽

pp. 307-311 ◽

Cited By ~ 7

Author(s):

Jinqing Yu ◽

Weimin Zhou ◽

Xiaolin Jin ◽

Lihua Cao ◽

Zongqing Zhao ◽

...

Keyword(s):

Energy Conversion ◽

Conversion Efficiency ◽

Proton Energy ◽

Rear Surface ◽

Energy Conversion Efficiency ◽

Rear Side ◽

Proton Acceleration ◽

Particle In Cell ◽

High Intensity Laser ◽

Cell Simulation

AbstractIn order to improve the total laser-proton energy conversion efficiency, a nanobrush target is proposed for proton acceleration and investigated by two-dimensional particle-in-cell simulation. The simulation results show that the nanobrush target significantly enhances the energy and number of hot electrons through the target rear side. Compared with plain target, the sheath field on the rear surface is increased near 100% and the total laser-proton energy conversion efficiency is prompted more than 70%. Furthermore, the proton divergence angle is less than 30° by using nanobrush target. The proposed target may serve as a new method to increase the energy conversion efficiency from laser to protons.

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Efficient Laser-Driven Proton Acceleration from a Cryogenic Solid Hydrogen Target

Scientific Reports ◽

10.1038/s41598-019-52919-7 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

J. Polz ◽

A. P. L. Robinson ◽

A. Kalinin ◽

G. A. Becker ◽

R. A. Costa Fraga ◽

...

Keyword(s):

Laser Pulses ◽

Solid Hydrogen ◽

Successful Implementation ◽

Power Laser ◽

Hydrogen Target ◽

Proton Acceleration ◽

Particle In Cell ◽

Thermal Features ◽

Terawatt Laser

Abstract We report on the successful implementation and characterization of a cryogenic solid hydrogen target in experiments on high-power laser-driven proton acceleration. When irradiating a solid hydrogen filament of 10 μm diameter with 10-Terawatt laser pulses of 2.5 J energy, protons with kinetic energies in excess of 20 MeV exhibiting non-thermal features in their spectrum were observed. The protons were emitted into a large solid angle reaching a total conversion efficiency of several percent. Two-dimensional particle-in-cell simulations confirm our results indicating that the spectral modulations are caused by collisionless shocks launched from the surface of the the high-density filament into a low-density corona surrounding the target. The use of solid hydrogen targets may significantly improve the prospects of laser-accelerated proton pulses for future applications.

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Characterization of laser-driven proton acceleration from water microdroplets

Scientific Reports ◽

10.1038/s41598-019-53587-3 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Georg A. Becker ◽

Matthew B. Schwab ◽

Robert Lötzsch ◽

Stefan Tietze ◽

Diethard Klöpfel ◽

...

Keyword(s):

Proton Energy ◽

Laser Energy ◽

Strong Electric Field ◽

Grazing Incidence ◽

Optical Probe ◽

Hot Electrons ◽

Probe Laser ◽

Angle Of Incidence ◽

Hot Electron ◽

Proton Acceleration

AbstractWe report on a proton acceleration experiment in which high-intensity laser pulses with a wavelength of 0.4 μm and with varying temporal intensity contrast have been used to irradiate water droplets of 20 μm diameter. Such droplets are a reliable and easy-to-implement type of target for proton acceleration experiments with the potential to be used at very high repetition rates. We have investigated the influence of the laser’s angle of incidence by moving the droplet along the laser polarization axis. This position, which is coupled with the angle of incidence, has a crucial impact on the maximum proton energy. Central irradiation leads to an inefficient coupling of the laser energy into hot electrons, resulting in a low maximum proton energy. The introduction of a controlled pre-pulse produces an enhancement of hot electron generation in this geometry and therefore higher proton energies. However, two-dimensional particle-in-cell simulations support our experimental results confirming, that even slightly higher proton energies are achieved under grazing laser incidence when no additional pre-plasma is present. Illuminating a droplet under grazing incidence generates a stream of hot electrons that flows along the droplet’s surface due to self-generated electric and magnetic fields and ultimately generates a strong electric field responsible for proton acceleration. The interaction conditions were monitored with the help of an ultra-short optical probe laser, with which the plasma expansion could be observed.

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Generation of hemispherical fast electron waves in the presence of preplasma in ultraintense laser-matter interaction

Laser and Particle Beams ◽

10.1017/s0263034613000359 ◽

2013 ◽

Vol 31 (3) ◽

pp. 379-386 ◽

Cited By ~ 5

Author(s):

X. H. Yang ◽

Y. Y. Ma ◽

H. Xu ◽

F. Q. Shao ◽

M.Y. Yu ◽

...

Keyword(s):

Ponderomotive Force ◽

Plasma Waves ◽

Laser Wavelength ◽

Resonance Absorption ◽

Hot Electrons ◽

Solid Target ◽

Particle In Cell ◽

Hemispherical Shell ◽

Matter Interaction ◽

Cell Simulation

AbstractHemispherical electron plasma waves generated from ultraintense laser interacting with a solid target having a subcritical preplasma is studied using particle-in-cell simulation. As the laser pulse propagates inside the preplasma, it becomes self-focused due to the response of the plasma electrons to the ponderomotive force. The electrons are mainly heated via betatron resonance absorption and their thermal energy can become higher than the ponderomotive energy. The hot electrons easily penetrate through the thin solid target and appear behind it as periodic hemispherical shell-like layers separated by the laser wavelength.

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Laser-driven proton acceleration from ultrathin foils with nanoholes

Scientific Reports ◽

10.1038/s41598-021-84264-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Giada Cantono ◽

Alexander Permogorov ◽

Julien Ferri ◽

Evgeniya Smetanina ◽

Alexandre Dmitriev ◽

...

Keyword(s):

Ultrashort Laser Pulse ◽

Laser Pulses ◽

Maximum Energy ◽

Power Laser ◽

Proton Acceleration ◽

Particle In Cell ◽

Target Plasma ◽

Ultrashort Laser ◽

Nanometric Size ◽

Scale Length

AbstractStructured solid targets are widely investigated to increase the energy absorption of high-power laser pulses so as to achieve efficient ion acceleration. Here we report the first experimental study of the maximum energy of proton beams accelerated from sub-micrometric foils perforated with holes of nanometric size. By showing the lack of energy enhancement in comparison to standard flat foils, our results suggest that the high contrast routinely achieved with a double plasma mirror does not prevent damaging of the nanostructures prior to the main interaction. Particle-in-cell simulations support that even a short scale length plasma, formed in the last hundreds of femtoseconds before the peak of an ultrashort laser pulse, fills the holes and hinders enhanced electron heating. Our findings reinforce the need for improved laser contrast, as well as for accurate control and diagnostics of on-target plasma formation.

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ENERGETIC PROTON ACCELERATION BY ULTRAINTENSE LASER PULSES IN INHOMOGENEOUS PLASMA TARGETS

International Journal of Modern Physics B ◽

10.1142/s021797920704246x ◽

2007 ◽

Vol 21 (03n04) ◽

pp. 642-646 ◽

Cited By ~ 1

Author(s):

A. ABUDUREXITI ◽

Y. MIKADO ◽

T. OKADA

Keyword(s):

Laser Pulse ◽

Inhomogeneous Plasma ◽

Laser Pulses ◽

Proton Acceleration ◽

Particle In Cell ◽

Target Plasma ◽

Plasma Target ◽

Experimental Process ◽

Foil Target ◽

Proton Bunch

Particle-in-Cell (PIC) simulations of fast particles produced by a short laser pulse with duration of 40 fs and an intensity of 1020W/cm2 interacting with a foil target are performed. The experimental process is numerically simulated by considering a triangular concave target illuminated by an ultraintense laser. We have demonstrated increased acceleration and higher proton energies for triangular concave targets. We also determined the optimum target plasma conditions for maximum proton acceleration. The results indicated that a change in the plasma target shape directly affects the degree of contraction accelerated proton bunch.

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