scholarly journals Laser-Plasma Accelerated Protons: Energy Increase in Gas-Mixtures Using High Mass Number Atomic Species

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 150 ◽  
Author(s):  
Tadzio Levato ◽  
Leonardo V. Goncalves ◽  
Vincenzo Giannini
Keyword(s):  
Mass Number ◽  
Hydrogen Plasma ◽  
Critical Density ◽  
High Mass ◽  
Gas Mixture ◽  
Pure Hydrogen ◽  
Particle In Cell ◽  
Accelerated Protons ◽  
Number Species ◽  
High Mass Number

The idea of using a gas-mixture comprising atoms with a high mass number in order to increase proton energies in laser induced plasma acceleration at critical density is investigated by means of 2D PIC (Particle-In-Cell) simulations. Comparing and discussing the case of a pure hydrogen plasma and that of a plasma containing higher mass number species with a small percentage of hydrogen, we demonstrate that the mixture enhances the energies of the accelerated protons. We also show that using a gas-mixture introduces the possibility of using the densities ratio in order to change the relative acceleration of the species.

scholarly journals Effective laser driven proton acceleration from near critical density hydrogen plasma

2016 ◽  
Vol 34 (2) ◽  
pp. 219-229 ◽  
Author(s):  
Ashutosh Sharma ◽  
Alexander Andreev
Keyword(s):  
Laser Pulse ◽  
Hydrogen Plasma ◽  
Three Dimensional ◽  
Critical Density ◽  
High Energy ◽  
Intense Laser ◽  
Proton Density ◽  
Proton Acceleration ◽  
Pic Simulation ◽  
Particle In Cell

AbstractRecent advances in the production of high repetition, high power, and short laser pulse have enabled the generation of high-energy proton beam, required for technology and other medical applications. Here we demonstrate the effective laser driven proton acceleration from near-critical density hydrogen plasma by employing the short and intense laser pulse through three-dimensional (3D) particle-in-cell (PIC) simulation. The generation of strong magnetic field is demonstrated by numerical results and scaled with the plasma density and the electric field of laser. 3D PIC simulation results show the ring shaped proton density distribution where the protons are accelerated along the laser axis with fairly low divergence accompanied by off-axis beam of ring-like shape.

scholarly journals Enhanced Proton Acceleration by Laser-Driven Collisionless Shock in the Near-Critical Density Target Embedding with Solid Nanolayers

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yue Chao ◽  
Xinxin Yan ◽  
Rui Xie ◽  
Lihua Cao ◽  
Chunyang Zheng ◽  
...  
Keyword(s):  
Critical Density ◽  
Inhomogeneous Magnetic Field ◽  
Shock Acceleration ◽  
Collisionless Shock ◽  
Incident Laser ◽  
Proton Acceleration ◽  
Particle In Cell ◽  
Peak Energy ◽  
Accelerated Protons ◽  
Gap Width

Effects of solid nanolayers embedded in a near-critical density plasma on the laser-driven collisionless shock acceleration are investigated by using two-dimensional particle-in-cell simulations. Due to the interaction of nanolayers and the incident laser, an additional number of hot electrons are generated and an inhomogeneous magnetic field is induced. As a result, the collisionless shock is reinforced within the nanolayer gaps compared to the target without the structured nanolayers. When the laser intensity is 9.8 × 10 19  W / cm 2 , the amplitude of the electrostatic field is increased by 30% and the shock velocity is increased from 0.079c to 0.091c, leading to an enhancement of the peak energy and the cutoff energy of accelerated protons, from 6.9 MeV to 9.1 MeV and 12.2 MeV to 20.0 MeV, respectively. Furthermore, the effects of the width of the nanolayer gaps are studied, by adjusting the gap width of nanolayers, and optimal nanolayer setups for collisionless shock acceleration can be acquired.

Post-solitons and electron vortices generated by femtosecond intense laser interacting with uniform near-critical-density plasmas

2021 ◽  
Author(s):  
Dong-Ning Yue ◽  
Min Chen ◽  
Yao Zhao ◽  
Pan-Fei Geng ◽  
Xiao-Hui Yuan ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Critical Density ◽  
Laser Pulses ◽  
Intense Laser ◽  
Nonlinear Structures ◽  
Particle In Cell ◽  
Laser Propagation ◽  
Laser Driver ◽  
Linearly Polarized ◽  
Dimensional Simulation

Abstract Generation of nonlinear structures, such as stimulated Raman side scattering waves, post-solitons and electron vortices, during ultra-short intense laser pulse transportation in near-critical-density (NCD) plasmas are studied by using multi-dimensional particle-in-cell (PIC) simulations. In two-dimensional geometries, both P- and S- polarized laser pulses are used to drive these nonlinear structures and to check the polarization effects on them. In the S-polarized case, the scattered waves can be captured by surrounding plasmas leading to the generation of post-solitons, while the main pulse excites convective electric currents leading to the formation of electron vortices through Kelvin-Helmholtz instability (KHI). In the P-polarized case, the scattered waves dissipate their energy by heating surrounding plasmas. Electron vortices are excited due to the hosing instability of the drive laser. These polarization dependent physical processes are reproduced in two different planes perpendicular to the laser propagation direction in three-dimensional simulation with linearly polarized laser driver. The current work provides inspiration for future experiments of laser-NCD plasma interactions.

scholarly journals Accelerated protons from near critical density gaseous targets

2016 ◽  
Author(s):  
Michael H. Helle ◽  
Daniel F. Gordon ◽  
Dmitri Kaganovich ◽  
Anthony Zingale ◽  
Antonio Ting
Keyword(s):  
Critical Density ◽  
Accelerated Protons

A pretreatment process for enhanced diamond nucleation on smooth silicon substrates coated with hard carbon films

1994 ◽  
Vol 9 (8) ◽  
pp. 2148-2153 ◽  
Author(s):  
Z. Feng ◽  
K. Komvopoulos ◽  
I.G. Brown ◽  
D.B. Bogy
Keyword(s):  
Microwave Plasma ◽  
Hydrogen Plasma ◽  
Carbon Film ◽  
Laser Raman Spectroscopy ◽  
Spherical Particles ◽  
Nucleation Density ◽  
Silicon Substrates ◽  
Pure Hydrogen ◽  
Hard Carbon ◽  
Diamond Nucleation

Diamond nucleation on unscratched silicon substrates coated with thin films of hard carbon was investigated experimentally with a microwave plasma-assisted chemical vapor deposition system. A new pretreatment process was used to enhance the nucleation of diamond. Relatively high diamond nucleation densities of ∼108 cm−2 were achieved by pretreating the carbon-coated silicon substrates with a methane-rich hydrogen plasma at a relatively low temperature for an hour. Scanning electron microscopy and laser Raman spectroscopy studies revealed that diamond nucleation occurred from nanometer-sized spherical particles of amorphous carbon produced during the pretreatment. The nanoparticles possessed a structure different from that of the original hard carbon film, with a broad non-diamond Raman peak centered at ∼1500 cm−1, and a high etching resistance in pure hydrogen plasma. The high diamond nucleation density is attributed to the significant percentage of tetrahedrally bonded (sp3) atomic carbon configurations in the nanoparticles and the presence of sufficient high-surface free-energy sites on the pretreated surfaces.

Vapor Condensation and Absorption of SO2 in Wet Flue Gas

2003 ◽  
Author(s):  
Li Jia ◽  
Xiaofeng Peng
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Flue Gas ◽  
Phase Interface ◽  
Vapor Condensation ◽  
High Mass ◽  
Condensation Process ◽  
Gas Mixture ◽  
Vapor Fraction ◽  
So2 Absorption

The convection-condensation heat transfer mechanism of the gas mixture and its influence on SO2 absorption were theoretically analyzed with vapor fraction of 8% to 28%. A modified film model of mass transfer in mixture gas and Nusselt theory were used to describe the characteristics of mass, momentum and energy transfer at the phase interface. The effects of the velocities induced by mass transfer (vapor condensation and SO2 absorption) were included in conducting governing equations. Vapor condensation improves the SO2 absorption in the wet flue gas. Vapor fraction in the gas mixture would alter the mechanism of heat transfer modes, single-phase convection or condensation. But for high mass fraction of vapor the SO2 absorption will be an important phenomenon in the condensation process. Another important factor influencing the SO2 absorption is the Re number of bulk flow of wet flue gas.

CLUSTER PHYSICS WITH DARK ENERGY

2011 ◽  
Vol 20 (08) ◽  
pp. 1327-1337
Author(s):  
SEOKCHEON LEE
Keyword(s):  
Dark Energy ◽  
Critical Density ◽  
Mass Region ◽  
High Mass ◽  
Cluster Number ◽  
The Press ◽  
Energy Dependent ◽  
The Universe ◽  
Matter Energy ◽  
Mass Fluctuation

Dark energy affects the abundance and evolution of clusters owing to their dependence on the geometry of the Universe and the power spectrum. Usually, there exits the degeneracy between σ8 and the matter energy density contrast [Formula: see text]. We avoid this by using the explicit dark energy dependent rms linear mass fluctuation σ8 which is consistent with the CMB normalization for general constant dark energy equation of state, ω Q . When we use the correct value of the critical density threshold δc = 1.58 into the cluster number density n calculation in the Press–Schechter (PS) formalism, PS formalism predicts the cluster number consistent with both simulation and observed data at the high mass region. The improved coefficients of Sheth–Tormen (ST) formalism by using the correct δc is also obtained. We found that changing ω Q by Δω Q = -0.1 from ω Q = -1.0 causes the changing of the comoving numbers of high mass clusters of M = 1016h-1M⊙ by about 20 and 40% at z = 0 and 1, respectively.

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