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.

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 Bremsstrahlung emission profile from intense laser-solid interactions as a function of laser focal spot size

2019 ◽  
Vol 61 (3) ◽  
pp. 034001 ◽  
Author(s):  
C D Armstrong ◽  
C M Brenner ◽  
E Zemaityte ◽  
G G Scott ◽  
D R Rusby ◽  
...  
Keyword(s):  
Focal Spot ◽  
Spot Size ◽  
Intense Laser ◽  
Focal Spot Size ◽  
Emission Profile ◽  
Bremsstrahlung Emission ◽  
Laser Focal Spot ◽  
Laser Solid Interactions

Measuring Gravitational Effect of Superintense Laser by Spin-Squeezed Bose-Einstein Condensates Interferometer

2021 ◽  
Author(s):  
Eng Boon Ng ◽  
C. H. Raymond Ooi
Keyword(s):  
Gravitational Force ◽  
Einstein Field Equation ◽  
Gravitational Effect ◽  
Atom Interferometer ◽  
Intense Laser ◽  
Squeezing Effect ◽  
Intense Laser Field ◽  
High Intensity Laser ◽  
Bose Einstein ◽  
Intensity Laser

Abstract In this article, we consider an extremely intense laser, enclosed by an atom interferometer. The gravitational potential generated from the high-intensity laser is solved from the Einstein field equation under the Newtonian limit. We compute the strength of the gravitational force and study the feasibility of measuring the force by the atom interferometer. The intense laser field from the laser pulse can induce a phase change in the interferometer with Bose-Einstein condensates. We push up the sensitivity limit of the interferometer with Bose-Einstein condensates by spin-squeezing effect and determine the sensitivity gap for measuring the gravitational effect from intense laser by atom interferometer.

scholarly journals Single-shot electrons and protons time-resolved detection from high-intensity laser–solid matter interactions at SPARC_LAB

2019 ◽  
Vol 7 ◽  
Author(s):  
F. Bisesto ◽  
M. Galletti ◽  
M. P. Anania ◽  
M. Ferrario ◽  
R. Pompili ◽  
...  
Keyword(s):  
Intense Laser ◽  
Test Facility ◽  
Particle Accelerators ◽  
Single Shot ◽  
X Rays ◽  
Time Resolved ◽  
Laser Plasma Interactions ◽  
High Intensity Laser ◽  
Set Up ◽  
Intensity Laser

Laser–plasma interactions have been studied in detail over the past twenty years, as they show great potential for the next generation of particle accelerators. The interaction between an ultra-intense laser and a solid-state target produces a huge amount of particles: electrons and photons (X-rays and $\unicode[STIX]{x03B3}$ -rays) at early stages of the process, with protons and ions following them. At SPARC_LAB Test Facility we have set up two diagnostic lines to perform simultaneous temporally resolved measurements on both electrons and protons.

scholarly journals Upper-limit power for self-guided propagation of intense lasers in underdense plasma

2013 ◽  
Vol 1 (2) ◽  
pp. 74-79 ◽  
Author(s):  
Wei-Min Wang ◽  
Zheng-Ming Sheng ◽  
Yu-Tong Li ◽  
Jie Zhang
Keyword(s):  
Lower Limit ◽  
Critical Power ◽  
Spot Size ◽  
Laser Spot Size ◽  
Particle In Cell ◽  
Upper Limit ◽  
Power Set ◽  
Guided Propagation ◽  
Underdense Plasma ◽  
Limit Power

AbstractIt is found that there is an upper-limit critical power for self-guided propagation of intense lasers in plasma in addition to the well-known lower-limit critical power set by the relativistic effect. Above this upper-limit critical power, the laser pulse experiences defocusing due to expulsion of local plasma electrons by the transverse ponderomotive force. Associated with the upper-limit power, a lower-limit critical plasma density is also found for a given laser spot size, below which self-focusing does not occur for any laser power. Both the upper-limit power and the lower-limit density are derived theoretically and verified by two-dimensional particle-in-cell simulations. The present study provides new guidance for experimental designs, where self-guided propagation of lasers is essential.

Effect of obliquely external magnetic field on the intense laser pulse propagating in plasma medium

2020 ◽  
Vol 34 (07) ◽  
pp. 2050044
Author(s):  
Mehdi Abedi-Varaki
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Laser Pulse ◽  
Magnetoactive Plasma ◽  
Spot Size ◽  
The Self ◽  
Intense Laser ◽  
Intense Laser Pulse ◽  
Laser Spot Size ◽  
Self Focusing

In this paper, self-focusing of intense laser pulse propagating along the obliquely external magnetic field on the collisional magnetoactive plasma by using the perturbation theory have been studied. The wave equation describing the interaction of intense laser pulse with collisional magnetoactive plasma is derived. In addition, employing source-dependent expansion (SDE) method, the analysis of the laser spot-size is discussed. It is shown that with increasing of the angle in obliquely external magnetic field, the spot-size of laser pulse decreases and as a result laser pulse becomes more focused. Furthermore, it is concluded that the self-focusing quality of the laser pulse has been enhanced due to the presence of obliquely external magnetic field in the collisional magnetoactive plasma. Besides, it is seen that with increasing of [Formula: see text], the laser spot-size reduces and subsequently the self-focusing of the laser pulse in plasma enhances. Moreover, it is found that changing the collision effect in the magnetoactive plasma leads to increases of self-focusing properties.

scholarly journals The Alfvén limit revisited and its relevance to laser-plasma interactions

2006 ◽  
Vol 24 (2) ◽  
pp. 299-310 ◽  
Author(s):  
J.R. DAVIES
Keyword(s):  
Conservation Of Energy ◽  
Laser Plasma Interactions ◽  
Current Limit ◽  
Original Estimate ◽  
High Intensity Laser ◽  
Uniform Current ◽  
Current Densities ◽  
A Charge ◽  
Intensity Laser ◽  
Laser Solid Interactions

Alfvén's derivation of his current limit is given. It demonstrates that it does not give the maximum possible current of a beam, but the maximum current that can propagate for an indefinite distance and time, from a source, in a charge neutral beam. Furthermore, the value Alfvén obtained applies to a uniform current density and to particles initially moving in the direction of the beam. It is also shown that Alfvén predicted that beams which exceed the limit will filament as a result of the particles that are turned back by the magnetic field. His work is extended to beams with particles that have transverse momentum, to beams with non-uniform current densities, to beams that are not charge neutral and to the time dependent case. These extensions of Alfvén's work are found to require numerical calculations in most cases and to give ambiguous results in some cases. A general formula for the current limit is given based on the conservation of energy. It is calculated for the cases considered previously and found to confirm the accuracy of Alfvén's original estimate. The relevance of the current limit to high intensity laser-solid interactions and fast ignition is then discussed.

Molecules in high-intensity laser fields

1996 ◽  
Vol 74 (6) ◽  
pp. 1236-1247 ◽  
Author(s):  
T.-T. Nguyen-Dang ◽  
F. Châteauneuf ◽  
S. Manoli
Keyword(s):  
High Order ◽  
Molecular Structures ◽  
Intense Laser ◽  
Intense Laser Field ◽  
Strongly Coupled ◽  
System A ◽  
High Intensity Laser ◽  
Quantized Field ◽  
Quantized Radiation Field ◽  
Intensity Laser

The separability of a dressed molecule, a composite molecule + quantized radiation field system, at high field intensities is examined. Various forms of the Hamiltonian describing the dressed molecule are reviewed and are used to assess the zeroth-order separability of the dressed system. A new high-order adiabatic separation between the strongly coupled quantized field and molecular subsystems is derived. Qualitative manifestations of laser-induced molecular structures are discussed within this high-order adiabatic representation. Key words: dynamics, dressed molecule, intense laser field, adiabatic separation, laser-induced molecular structure.

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