scholarly journals Suppression of stochastic pulsation in laser–plasma interaction by smoothing methods

1993 ◽  
Vol 11 (1) ◽  
pp. 177-184 ◽  
Author(s):  
M. Aydin ◽  
H. Hora

Smoothing of laser-plasma interaction by ISI, RPP, SSD, etc. was mainly directed to overcome lateral nonuniformity of irradiation. While these problems are in no way less important, we derived numerically the model of the Laue rippling and hydrorelaxation model for explanation of the measured temporal pulsation in the 10- to 40-ps range and how the smoothing schemes suppress these pulsations. The partial standing wave fields of the normally coherent laser-irradiated plasma corona is then suppressed by smoothing and conclusion for tests for this model, e.g., by the “question mark experiment” is given. The result provides a physics solution of the laser interaction problem for direct-drive inertial fusion energy

1991 ◽  
Vol 9 (2) ◽  
pp. 381-395 ◽  
Author(s):  
Gu Min ◽  
H. Hora

In recent years experimental results about the pulsation of reflectivity or 3ω/2 harmonics from laser-irradiated plasma with a period of 10–20 ps initiated a reconsideration of a broad field of phenomena of laser-plasma interaction. We present here numerical results from a very general hydrodynamic computation showing that the pulsation is due to a standing-wave-produced density ripple in the widespread plasma corona causing these after 2 ps at Laue-Bragg reflection at very low density, followed by a hydrodynamic relaxation of the ripple. This cycle has a turnaround time of about 6–10 ps and immediately explains the observation of pulsation. The suppression of pulsation and the achievement of smooth direct drive is then understood by a washing-out process of the ripples when using the random-phase plate (RPP) or broadband irradiation, or by just preventing the buildup of the ripple at the induced spatial incoherence (ISI), where coherence of the laser field is 1 or 2 ps only.


1982 ◽  
Vol 28 (3) ◽  
pp. 485-493 ◽  
Author(s):  
J. T. Mendonça ◽  
F. Doveil

The interaction of an electron with two electromagnetic waves propagating in an isotropic plasma is studied. It is shown, by numerical calculations, that the electron behaves stochastically, above a given threshold of the wave field amplitudes. The numerical threshold is compared with those given by analytical criteria. The results might be relevant to the laser-plasma interaction problem.


2016 ◽  
Vol 717 ◽  
pp. 012040 ◽  
Author(s):  
J F Myatt ◽  
J Shaw ◽  
V N Goncharov ◽  
J Zhang ◽  
A V Maximov ◽  
...  

2006 ◽  
Vol 24 (3) ◽  
pp. 455-463 ◽  
Author(s):  
HEINRICH HORA

Stochastic pulsation of laser-plasma interaction in the range of a few to dozens of picoseconds, due to standing wave produced density ripples, needs more attention than in the past, in view of the recent developments. This is important if nanosecond laser pulses produce a pre-compression that is a thousand times the solid state density of DT for fast ignition as well as for treatment of ps laser interaction. The following is an updated summary of these properties where the laser beam smoothing is essential. The use of smoothing is not only an empirical game with experiments for improving the interaction, but it is necessary to be aware of the mechanisms involved for understanding how the pulsation is overcome, and conclusions can be derived systematically for further improvements and control of the phenomena.


Author(s):  
V. T. Tikhonchuk

In this paper, I consider the motivations, recent results and perspectives for the inertial confinement fusion (ICF) studies in Europe. The European approach is based on the direct drive scheme with a preference for the central ignition boosted by a strong shock. Compared to other schemes, shock ignition offers a higher gain needed for the design of a future commercial reactor and relatively simple and technological targets, but implies a more complicated physics of laser–target interaction, energy transport and ignition. European scientists are studying physics issues of shock ignition schemes related to the target design, laser plasma interaction and implosion by the code developments and conducting experiments in collaboration with US and Japanese physicists, providing access to their installations Omega and Gekko XII. The ICF research in Europe can be further developed only if European scientists acquire their own academic laser research facility specifically dedicated to controlled fusion energy and going beyond ignition to the physical, technical, technological and operational problems related to the future fusion power plant. Recent results show significant progress in our understanding and simulation capabilities of the laser plasma interaction and implosion physics and in our understanding of material behaviour under strong mechanical, thermal and radiation loads. In addition, growing awareness of environmental issues has attracted more public attention to this problem and commissioning at ELI Beamlines the first high-energy laser facility with a high repetition rate opens the opportunity for qualitatively innovative experiments. These achievements are building elements for a new international project for inertial fusion energy in Europe. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.


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