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.

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 High-repetition-rate ( kHz) targets and optics from liquid microjets for high-intensity laser–plasma interactions

2019 ◽  
Vol 7 ◽  
Author(s):  
K. M. George ◽  
J. T. Morrison ◽  
S. Feister ◽  
G. K. Ngirmang ◽  
J. R. Smith ◽  
...  
Keyword(s):  
Laser Plasma ◽  
Repetition Rate ◽  
High Intensity ◽  
High Repetition Rate ◽  
Plasma Interactions ◽  
Laser Plasma Interactions ◽  
High Repetition ◽  
High Intensity Laser ◽  
Liquid Microjets ◽  
Intensity Laser

High-intensity laser–plasma interactions produce a wide array of energetic particles and beams with promising applications. Unfortunately, the high repetition rate and high average power requirements for many applications are not satisfied by the lasers, optics, targets, and diagnostics currently employed. Here, we aim to address the need for high-repetition-rate targets and optics through the use of liquids. A novel nozzle assembly is used to generate high-velocity, laminar-flowing liquid microjets which are compatible with a low-vacuum environment, generate little to no debris, and exhibit precise positional and dimensional tolerances. Jets, droplets, submicron-thick sheets, and other exotic configurations are characterized with pump–probe shadowgraphy to evaluate their use as targets. To demonstrate a high-repetition-rate, consumable, liquid optical element, we present a plasma mirror created by a submicron-thick liquid sheet. This plasma mirror provides etalon-like anti-reflection properties in the low field of 0.1% and high reflectivity as a plasma, 69%, at a repetition rate of 1 kHz. Practical considerations of fluid compatibility, in-vacuum operation, and estimates of maximum repetition rate are addressed. The targets and optics presented here demonstrate a potential technique for enabling the operation of laser–plasma interactions at high repetition rates.

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 Burst behavior due to the quasimode excited by stimulated Brillouin scattering in high-intensity laser–plasma interactions

2019 ◽  
Vol 7 ◽  
Author(s):  
Q. S. Feng ◽  
L. H. Cao ◽  
Z. J. Liu ◽  
C. Y. Zheng ◽  
X. T. He
Keyword(s):  
Laser Plasma ◽  
High Intensity ◽  
Brillouin Scattering ◽  
Low Frequency ◽  
Stimulated Brillouin Scattering ◽  
Plasma Interactions ◽  
Laser Plasma Interactions ◽  
High Intensity Laser ◽  
Stimulated Brillouin ◽  
Intensity Laser

The strong-coupling mode, called the “quasimode”, is excited by stimulated Brillouin scattering (SBS) in high-intensity laser–plasma interactions. Also SBS of the quasimode competes with SBS of the fast mode (or slow mode) in multi-ion species plasmas, thus leading to a low-frequency burst behavior of SBS reflectivity. Competition between the quasimode and the ion-acoustic wave (IAW) is an important saturation mechanism of SBS in high-intensity laser–plasma interactions. These results give a clear explanation of the low-frequency periodic burst behavior of SBS and should be considered as a saturation mechanism of SBS in high-intensity laser–plasma interactions.

High-intensity laser-plasma interactions in the refluxing limit

2008 ◽  
Vol 15 (5) ◽  
pp. 056308 ◽  
Author(s):  
P. M. Nilson ◽  
W. Theobald ◽  
J. Myatt ◽  
C. Stoeckl ◽  
M. Storm ◽  
...  
Keyword(s):  
Laser Plasma ◽  
High Intensity ◽  
Plasma Interactions ◽  
Laser Plasma Interactions ◽  
High Intensity Laser ◽  
Intensity Laser

scholarly journals Ultrafast Electron Radiography of Magnetic Fields in High-Intensity Laser-Solid Interactions

2013 ◽  
Vol 110 (1) ◽  
Author(s):  
W. Schumaker ◽  
N. Nakanii ◽  
C. McGuffey ◽  
C. Zulick ◽  
V. Chyvkov ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
High Intensity ◽  
High Intensity Laser ◽  
Intensity Laser ◽  
Laser Solid Interactions
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