scholarly journals Scaling of ion energies in the relativistic-induced transparency regime

2015 ◽  
Vol 33 (4) ◽  
pp. 695-703 ◽  
Author(s):  
D. Jung ◽  
B.J. Albright ◽  
L. Yin ◽  
D.C. Gautier ◽  
B. Dromey ◽  
...  
Keyword(s):  
Linear Scaling ◽  
Analytic Model ◽  
Two Dimensional ◽  
Carbon Ions ◽  
Optimum Thickness ◽  
Particle In Cell ◽  
Ion Energies ◽  
Laser Systems ◽  
Induced Transparency ◽  
Good Agreement

AbstractExperimental data are presented showing maximum carbon C6+ ion energies obtained from nm-scaled targets in the relativistic transparent regime for laser intensities between 9 × 1019 and 2 × 1021 W/cm2. When combined with two-dimensional particle-in-cell simulations, these results show a steep linear scaling for carbon ions with the normalized laser amplitude a0 ($a_0 \propto \sqrt ( I)$). The results are in good agreement with a semi-analytic model that allows one to calculate the optimum thickness and the maximum ion energies as functions of a0 and the laser pulse duration τλ for ion acceleration in the relativistic-induced transparency regime. Following our results, ion energies exceeding 100 MeV/amu may be accessible with currently available laser systems.

scholarly journals Self-induced ionization injection LWFA and generation of sub-fs electron bunches with few-cycle sub-TW laser pulses

2019 ◽  
Vol 37 (2) ◽  
pp. 165-170
Author(s):  
D. Papp ◽  
N.A.M. Hafz ◽  
C. Kamperidis
Keyword(s):  
Relativistic Electron ◽  
Laser Pulses ◽  
Single Stage ◽  
Energy Spread ◽  
Two Dimensional ◽  
Linear Regime ◽  
Particle In Cell ◽  
Electron Bunches ◽  
Peak Energy ◽  
Laser Systems

AbstractWe investigate an ionization injection scheme in a “weakly” non-linear regime of a wakefield, driven by sub-TW, few-cycle laser pulses in a single-stage, high-Z gas. This medium simultaneously provides the background wake fluid electrons from its lower ionization states and the necessary dephased electrons from its higher ionization states. Two dimensional-particle-in-cell simulations show the generation of relativistic electron beamlets having up to 15 MeV peak energy, with a narrow energy-spread and sub-fs duration. Since the currently-available sub-TW, few-cycle laser systems operate at kHz repetition rates, the presented scheme is capable of producing kHz attosecond electron bunches and their associated radiations which can find unique applications, for instance, in attosecond diffraction and microscopy.

scholarly journals Efficient ion acceleration by collective laser-driven electron dynamics with ultra-thin foil targets

2010 ◽  
Vol 28 (1) ◽  
pp. 215-221 ◽  
Author(s):  
S. Steinke ◽  
A. Henig ◽  
M. Schnürer ◽  
T. Sokollik ◽  
P.V. Nickles ◽  
...  
Keyword(s):  
Thin Foil ◽  
Laser Pulses ◽  
Maximum Energy ◽  
Skin Depth ◽  
Ion Acceleration ◽  
Carbon Ions ◽  
Incident Laser ◽  
Particle In Cell ◽  
Incident Laser Pulse ◽  
Ion Energies

AbstractExperiments on ion acceleration by irradiation of ultra-thin diamond-like carbon (DLC) foils, with thicknesses well below the skin depth, irradiated with laser pulses of ultra-high contrast and linear polarization, are presented. A maximum energy of 13 MeV for protons and 71 MeV for carbon ions is observed with a conversion efficiency of ~10%. Two-dimensional particle-in-cell (PIC) simulations reveal that the increase in ion energies can be attributed to a dominantly collective rather than thermal motion of the foil electrons, when the target becomes transparent for the incident laser pulse.

The mechanics of dunes and antidunes in erodible-bed channels

1963 ◽  
Vol 16 (4) ◽  
pp. 521-544 ◽  
Author(s):  
John F. Kennedy
Keyword(s):  
Fluid Velocity ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Analytic Model ◽  
Two Dimensional ◽  
Dominant Wavelength ◽  
Fluid Bed ◽  
The Stability ◽  
Amplitude Growth ◽  
Good Agreement

An analytic model of free-surface flow over an erodible bed is developed and used to investigate the stability of the fluid-bed interface and the characteristics of the bed features. The model is based on the potential flow over a two-dimensional, moving, wavy bed with a sinusoidal profile of varying amplitude, and a sediment transport relation in which the transport rate is proportional to a power of the fluid velocity at the level of the bed. By assuming that the dominant wavelength is that for which the rate of amplitude growth is the greatest, expressions are obtained for the wavelength and velocity of the bed features. In addition, conditions for the occurrence of the different configurations, dunes, flat bed, and antidunes, are found from the model. The predicted wavelengths of antidunes and ranges of wavelengths of dunes, and the predicted conditions for change of bed configuration are found to be in good agreement with experimental data. Finally, brief consideration is given to the factors involved in determining the maximum heights of the bed features and surface waves.

scholarly journals GeV laser ion acceleration from ultrathin targets: The laser break-out afterburner

2006 ◽  
Vol 24 (2) ◽  
pp. 291-298 ◽  
Author(s):  
L. YIN ◽  
B. J. ALBRIGHT ◽  
B. M. HEGELICH ◽  
J. C. FERNÁNDEZ
Keyword(s):  
Scaling Laws ◽  
Laser Intensity ◽  
Ion Acceleration ◽  
Carbon Ions ◽  
Particle In Cell ◽  
Acceleration Mechanism ◽  
Early Stages ◽  
Laser Systems

A new laser-driven ion acceleration mechanism has been identified using particle-in-cell (PIC) simulations. This mechanism allows ion acceleration to GeV energies at vastly reduced laser intensities compared with earlier acceleration schemes. The new mechanism, dubbed “Laser Break-out Afterburner” (BOA), enables the acceleration of carbon ions to greater than 2 GeV energy at a laser intensity of only 1021W/cm2, an intensity that has been realized in existing laser systems. Other techniques for achieving these energies in the literature rely upon intensities of 1024W/cm2or above, i.e., 2–3 orders of magnitude higher than any laser intensity that has been demonstrated to date. Also, the BOA mechanism attains higher energy and efficiency than target normal sheath acceleration (TNSA), where the scaling laws predict carbon energies of 50 MeV/u for identical laser conditions. In the early stages of the BOA, the carbon ions accelerate as a quasi-monoenergetic bunch with median energy higher than that realized recently experimentally.

scholarly journals Performance of Axial Compressor With Non-Uniform Exit Static Pressure

1985 ◽  
Author(s):  
Hidekazu Kodama
Keyword(s):  
Analytical Method ◽  
Static Pressure ◽  
Axial Compressor ◽  
Analytic Model ◽  
Two Dimensional ◽  
Pressure Perturbation ◽  
Axial Compressors ◽  
Disc Model ◽  
Actuator Disc ◽  
Good Agreement

An analytic model has been developed to predict the performance of axial compressors with an exit static pressure perturbation. The model uses a two dimensional compressible semi-actuator disc model. This method can be applied to the compressor with known circumferential variation in exit static pressure which is measured or predicted by an analytical method. The analytical results are found to be in good agreement with experiments carried out on two transonic fans.

scholarly journals Nonlinear two-dimensional free surface solutions of flow exiting a pipe and impacting a wedge

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Alex Doak ◽  
Jean-Marc Vanden-Broeck
Keyword(s):  
Surface Tension ◽  
Integral Equation ◽  
Free Surface ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Two Dimensional ◽  
Numerical Schemes ◽  
Additional Advantage ◽  
Infinite Wedge ◽  
Good Agreement

AbstractThis paper concerns the flow of fluid exiting a two-dimensional pipe and impacting an infinite wedge. Where the flow leaves the pipe there is a free surface between the fluid and a passive gas. The model is a generalisation of both plane bubbles and flow impacting a flat plate. In the absence of gravity and surface tension, an exact free streamline solution is derived. We also construct two numerical schemes to compute solutions with the inclusion of surface tension and gravity. The first method involves mapping the flow to the lower half-plane, where an integral equation concerning only boundary values is derived. This integral equation is solved numerically. The second method involves conformally mapping the flow domain onto a unit disc in the s-plane. The unknowns are then expressed as a power series in s. The series is truncated, and the coefficients are solved numerically. The boundary integral method has the additional advantage that it allows for solutions with waves in the far-field, as discussed later. Good agreement between the two numerical methods and the exact free streamline solution provides a check on the numerical schemes.

Two-dimensional particle-in-cell simulations of transport in a magnetized electronegative plasma

2010 ◽  
Vol 108 (10) ◽  
pp. 103305 ◽  
Author(s):  
E. Kawamura ◽  
A. J. Lichtenberg ◽  
M. A. Lieberman
Keyword(s):  
Two Dimensional ◽  
Particle In Cell ◽  
Electronegative Plasma

On Wall Effects in Cavity Flows

1984 ◽  
Vol 28 (01) ◽  
pp. 70-75
Author(s):  
C. C. Hsu
Keyword(s):  
Numerical Results ◽  
Cavity Flows ◽  
Two Dimensional ◽  
Wall Effects ◽  
Free Jet ◽  
Theoretical Predictions ◽  
Experimental Findings ◽  
Good Agreement

Simple wall correction rules for two-dimensional and nearly two-dimensional cavity flows in closed or free jet water tunnels, based on existing linearized analyses, are made. Numerical results calculated from these expressions are compared with existing experimental findings. The present theoretical predictions are, in general, in good agreement with data.

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