scholarly journals Diagnosis of Weibel instability evolution in the rear surface density scale lengths of laser solid interactions via proton acceleration

2017 ◽  
Vol 19 (4) ◽  
pp. 043010 ◽  
Author(s):  
G G Scott ◽  
C M Brenner ◽  
V Bagnoud ◽  
R J Clarke ◽  
B Gonzalez-Izquierdo ◽  
...  
Keyword(s):  
Surface Density ◽  
Rear Surface ◽  
Proton Acceleration ◽  
Weibel Instability ◽  
Laser Solid Interactions ◽  
Density Scale

scholarly journals Escaping Electrons from Intense Laser-Solid Interactions as a Function of Laser Spot Size

2018 ◽  
Vol 167 ◽  
pp. 02001 ◽  
Author(s):  
Dean Rusby ◽  
Ross Gray ◽  
Nick Butler ◽  
Rachel Dance ◽  
Graeme Scott ◽  
...  
Keyword(s):  
Rear Surface ◽  
Spot Size ◽  
Intense Laser ◽  
Laser Spot Size ◽  
Particle In Cell ◽  
High Intensity Laser ◽  
Electric Potentials ◽  
Initial Interaction ◽  
Intensity Laser ◽  
Laser Solid Interactions

The interaction of a high-intensity laser with a solid target produces an energetic distribution of electrons that pass into the target. These electrons reach the rear surface of the target creating strong electric potentials that act to restrict the further escape of additional electrons. The measurement of the angle, flux and spectra of the electrons that do escape gives insights to the initial interaction. Here, the escaping electrons have been measured using a differentially filtered image plate stack, from interactions with intensities from mid 1020-1017 W/cm2, where the intensity has been reduced by defocussing to increase the size of the focal spot. An increase in electron flux is initially observed as the intensity is reduced from 4x1020 to 6x1018 W/cm2. The temperature of the electron distribution is also measured and found to be relatively constant. 2D particle-in-cell modelling is used to demonstrate the importance of pre-plasma conditions in understanding these observations.

Effect of the Plasma Density Scale Length on the Direction of Fast Electrons in Relativistic Laser-Solid Interactions

2000 ◽  
Vol 84 (7) ◽  
pp. 1459-1462 ◽  
Author(s):  
M. I. K. Santala ◽  
M. Zepf ◽  
I. Watts ◽  
F. N. Beg ◽  
E. Clark ◽  
...  
Keyword(s):  
Plasma Density ◽  
Fast Electrons ◽  
Laser Solid Interactions ◽  
Density Scale ◽  
Scale Length

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

2012 ◽  
Vol 30 (2) ◽  
pp. 307-311 ◽  
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.

On the effect of rear-surface dielectric coatings on laser-driven proton acceleration

2009 ◽  
Vol 16 (10) ◽  
pp. 100701 ◽  
Author(s):  
S. Betti ◽  
C. A. Cecchetti ◽  
E. Förster ◽  
A. Gamucci ◽  
A. Giulietti ◽  
...  
Keyword(s):  
Rear Surface ◽  
Proton Acceleration ◽  
Dielectric Coatings

Improve beam quality of laser proton acceleration with funnel-shaped-hole target

2016 ◽  
Vol 30 (08) ◽  
pp. 1650045 ◽  
Author(s):  
Peng Yang ◽  
Da Peng Fan ◽  
Yu Xiao Li
Keyword(s):  
Proton Beam ◽  
Short Pulse ◽  
Beam Quality ◽  
Rear Surface ◽  
Beam Divergence ◽  
Optimal Size ◽  
Proton Acceleration ◽  
Shaped Hole ◽  
Laser Proton Acceleration

Improve beam quality of laser proton acceleration using a funnel-shaped-hole target is demonstrated through particle simulations. When an intense short pulse laser illuminates a thin foil target with a hole at the rear surface, the proton beam divergence is suppressed compared with that obtained in a traditional flat target. In this paper, a funnel-shaped-hole target is proposed to improve the proton beam quality. Using two-dimensional particle-in-cell (PIC) simulations, three different shapes of target (funnel-shaped-hole target, cylinder-shaped-hole target and flat target) are simulated and compared. The funnel-shaped hole in the rear surface of the target helps to focus the electron cloud significantly and improve the maximum proton energy and suppress the proton beam divergence. Different thicknesses of the new target are also simulated, and the effects of thickness on the divergence angle and proton spectra are investigated. The optimal size of the new target is obtained and the quality of the proton beam is improved significantly. The funnel-shaped-hole target serves as a new method to improve the proton beam quality in laser–plasma interactions.

scholarly journals Proton acceleration by fast electrons in laser–solid interactions

2002 ◽  
Vol 20 (2) ◽  
pp. 243-253 ◽  
Author(s):  
J.R. DAVIES
Keyword(s):  
Electric Field ◽  
Fast Electron ◽  
Proton Energy ◽  
High Energy ◽  
Dimensional Model ◽  
Proton Acceleration ◽  
Fast Electrons ◽  
One Dimensional ◽  
Long Pulse ◽  
Laser Solid Interactions

The emission of high-energy protons in laser–solid interactions and the theories that have been used to explain it are briefly reviewed. To these theories we add a further possibility: the acceleration of protons inside the target by the electric field generated by fast electrons. This is considered using a simple one-dimensional model. It is found that for relativistic laser intensities and sufficiently long pulse durations, the proton energy gain is typically several times the fast electron temperature. The results are very similar to those obtained for proton acceleration by electron expansion into vacuum.

scholarly journals Measurement of the angle, temperature and flux of fast electrons emitted from intense laser–solid interactions

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
D. R. Rusby ◽  
L. A. Wilson ◽  
R. J. Gray ◽  
R. J. Dance ◽  
N. M. H. Butler ◽  
...  
Keyword(s):  
High Intensity ◽  
Rear Surface ◽  
High Energy ◽  
Intense Laser ◽  
Rear Side ◽  
Measured Signal ◽  
X Rays ◽  
High Intensity Laser ◽  
Intensity Laser ◽  
Laser Solid Interactions

High-intensity laser–solid interactions generate relativistic electrons, as well as high-energy (multi-MeV) ions and x-rays. The directionality, spectra and total number of electrons that escape a target-foil is dependent on the absorption, transport and rear-side sheath conditions. Measuring the electrons escaping the target will aid in improving our understanding of these absorption processes and the rear-surface sheath fields that retard the escaping electrons and accelerate ions via the target normal sheath acceleration (TNSA) mechanism. A comprehensive Geant4 study was performed to help analyse measurements made with a wrap-around diagnostic that surrounds the target and uses differential filtering with a FUJI-film image plate detector. The contribution of secondary sources such as x-rays and protons to the measured signal have been taken into account to aid in the retrieval of the electron signal. Angular and spectral data from a high-intensity laser–solid interaction are presented and accompanied by simulations. The total number of emitted electrons has been measured as $2.6\times 10^{13}$ with an estimated total energy of $12\pm 1~\text{J}$ from a $100~{\rm\mu}\text{m}$ Cu target with 140 J of incident laser energy during a $4\times 10^{20}~\text{W}~\text{cm}^{-2}$ interaction.

scholarly journals Characterization of multiterawatt laser-solid interactions for proton acceleration

2002 ◽  
Vol 73 (12) ◽  
pp. 4176-4184 ◽  
Author(s):  
P. McKenna ◽  
K. W. D. Ledingham ◽  
I. Spencer ◽  
T. McCany ◽  
R. P. Singhal ◽  
...  
Keyword(s):  
Proton Acceleration ◽  
Laser Solid Interactions
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