Erratum: “SBS reflectivity from spatially smoothed laser beams: Random phase plates versus polarization smoothing” [Phys. Plasmas 5, 2706 (1998)]

1998 ◽  
Vol 5 (10) ◽  
pp. 3794-3794 ◽  
Author(s):  
S. Hüller ◽  
Ph. Mounaix ◽  
V. T. Tikhonchuk
Keyword(s):  
Random Phase ◽  
Laser Beams ◽  
Phase Plates

SBS reflectivity from spatially smoothed laser beams: Random phase plates versus polarization smoothing

1998 ◽  
Vol 5 (7) ◽  
pp. 2706-2711 ◽  
Author(s):  
S. Hüller ◽  
Ph. Mounaix ◽  
V. T. Tikhonchuk
Keyword(s):  
Random Phase ◽  
Laser Beams ◽  
Phase Plates

scholarly journals Optical smoothing for shock-wave generation: Application to the measurement of equations of state

1996 ◽  
Vol 14 (2) ◽  
pp. 211-223 ◽  
Author(s):  
Dimitri Batani ◽  
Simone Bossi ◽  
Alessandra Benuzzi ◽  
Michel Koenig ◽  
Bernard Faral ◽  
...  
Keyword(s):  
Shock Wave ◽  
Equations Of State ◽  
Random Phase ◽  
Laser Pulses ◽  
Wave Generation ◽  
Laser Beams ◽  
Solid Samples ◽  
Shock Wave Generation ◽  
Phase Plates ◽  
Shock Fronts

Experimental results are presented on shock-wave generation in solid samples, irradiated directly by optically smoothed laser beams. Random phase plates and phased zone plates have been successfully used. In particular, the last technique allowed the production of uniform shock fronts that have been used for equation of state experiments at pressures above 10 Mbar. Pressures higher than 35 Mbar were achieved in gold, by using laser pulses with energy E ≈ 100 J, and structured, two-step, two-material targets.

scholarly journals High-density compression experiments at ILE, Osaka

1991 ◽  
Vol 9 (2) ◽  
pp. 193-207 ◽  
Author(s):  
H. Azechi ◽  
T. Jitsuno ◽  
T. Kanabe ◽  
M. Katayama ◽  
K. Mima ◽  
...  
Keyword(s):  
Random Phase ◽  
Mass Conservation ◽  
Liquid Density ◽  
Direct Drive ◽  
One Dimensional ◽  
X Ray ◽  
Calculation Results ◽  
Phase Plates ◽  
Thermonuclear Ignition ◽  
Ablated Mass

Direct-drive implosion experiments on the GEKKO XII laser (9 kJ, 0.5 μm, 2 ns) with deuterium and tritium (DT) exchanged plastic hollow shell targets demonstrated fuel areal densities (ρR) of ˜0.1 g/cm2 and fuel densities of ˜600 times liquid density at fuel temperatures of ˜0.3 keV. (The density and ρR values refer only to DT and do not include carbons in the plastic targets.) These values are to be compared with thermonuclear ignition conditions, i.e., fuel densities of 500–1000 times liquid density, fuel areal densities greater than 0.3 g/cm2, and fuel temperatures greater than 5 keV. The irradiation nonuniformity in these experiments was significantly reduced to a level of <5% in root mean square by introducing random-phase plates. The target irregularity was controlled to a 1% level. The fuel ρR was directly measured with the neutron activation of Si, which was originally compounded in the plastic targets. The fuel densities were estimated from the ρR values using the mass conservation relation, where the ablated mass was separately measured using the time-dependent X-ray emission from multilayer targets. Although the observed densities were in agreement with one-dimensional calculation results with convergence ratios of 25–30, the observed neutron yields were significantly lower than those of the calculations. This suggests the implosion uniformity is not sufficient to create a hot spark in which most neutrons should be generated.

scholarly journals Focused beam control in super-ASHURA KrF laser system

1999 ◽  
Vol 17 (4) ◽  
pp. 693-699
Author(s):  
I. MATSUSHIMA ◽  
I. OKUDA ◽  
Y. MATSUMOTO ◽  
T. TOMIE ◽  
E. MIURA ◽  
...  
Keyword(s):  
High Efficiency ◽  
Laser System ◽  
Random Phase ◽  
Divergence Angle ◽  
Laser Fusion ◽  
Profile Control ◽  
Krf Laser ◽  
Speckle Patterns ◽  
Phase Plates ◽  
Focused Beam

Beam smoothing techniques and focused beam profile control techniques for high efficiency KrF laser fusion are reported. We have developed 1D and 2D broadband random phase (BRP) irradiation techniques. Our next idea is the combination of a laser oscillator with a wide beam divergence angle and phase plates. The wide divergence angle laser beam eliminates the speckle patterns caused by the phase plates. Well characterized focal spot patterns have been observed with the front-end pulse of the Super-ASHURA KrF laser system. Amplification experiments are on going.

scholarly journals An online diagnosis technique for simultaneous measurement of the fundamental, second and third harmonics in one snapshot

2019 ◽  
Vol 7 ◽  
Author(s):  
Xue Dong ◽  
Xingchen Pan ◽  
Cheng Liu ◽  
Jianqiang Zhu
Keyword(s):  
Random Phase ◽  
High Accuracy ◽  
Measurement Methods ◽  
Laser Beams ◽  
Phase Plate ◽  
Diffraction Intensity ◽  
Compact Structure ◽  
Laser Driver ◽  
Diffraction Patterns ◽  
Diagnosis Technique

A three-wavelength coherent-modulation-imaging (CMI) technique is proposed to simultaneously measure the fundamental, second and third harmonics of a laser driver in one snapshot. Laser beams at three wavelengths (1053 nm, 526.5 nm and 351 nm) were simultaneously incident on a random phase plate to generate hybrid diffraction patterns, and a modified CMI algorithm was adopted to reconstruct the complex amplitude of each wavelength from one diffraction intensity frame. The validity of this proposed technique was verified using both numerical simulation and experimental analyses. Compared to commonly used measurement methods, this proposed method has several advantages, including a compact structure, convenient operation and high accuracy.

Single and double passage interferometric analysis of Pseudo-Random-Phase-Plates

2015 ◽  
Vol 345 ◽  
pp. 37-46 ◽  
Author(s):  
Richa Sharma ◽  
C.S. Narayanamurthy
Keyword(s):  
Random Phase ◽  
Phase Plates

scholarly journals Implementation of a phase plate for the generation of homogeneous focal-spot intensity distributions at the high-energy short-pulse laser facility PHELIX

2019 ◽  
Vol 7 ◽  
Author(s):  
V. Bagnoud ◽  
J. Hornung ◽  
M. Afshari ◽  
U. Eisenbarth ◽  
C. Brabetz ◽  
...  
Keyword(s):  
Short Pulse ◽  
Random Phase ◽  
High Energy ◽  
Phase Plate ◽  
Work Related ◽  
Nanosecond Lasers ◽  
Short Pulse Laser ◽  
Laser Facility ◽  
Ultrashort Pulse Lasers ◽  
Phase Plates

We propose and demonstrate the use of random phase plates (RPPs) for high-energy sub-picosecond lasers. Contrarily to previous work related to nanosecond lasers, an RPP poses technical challenges with ultrashort-pulse lasers. Here, we implement the RPP near the beginning of the amplifier and image-relay it throughout the laser amplifier. With this, we obtain a uniform intensity distribution in the focus over an area 1600 times the diffraction limit. This method shows no significant drawbacks for the laser and it has been implemented at the PHELIX laser facility where it is now available for users.

scholarly journals Random-phase plate effects on burn-through measurements of laser-irradiated plane-layered targets

1994 ◽  
Vol 12 (1) ◽  
pp. 111-120
Author(s):  
R. Evans ◽  
Z. Ahmad ◽  
T.A. Hall ◽  
Y.A. Zakharenkov
Keyword(s):  
Hot Spots ◽  
Energy Transport ◽  
Random Phase ◽  
Outer Region ◽  
Local Maximum ◽  
Phase Plate ◽  
Energy Redistribution ◽  
Laser Focal Spot ◽  
Phase Plates ◽  
Burn Through

The application of random-phase plates in laser beams to improve the uniformity of target ablation is investigated by combining the simultaneous X-ray and particle emission measurements of ablation characteristics. It is shown that if some hot spots with dimensions of a few µm exist on target they persist at least during the initial stages of the laser interaction process, producing a local maximum in the ablation pressure. Lateral energy transport, inferred from the neutral particle measurements, has little influence on absorbed energy redistribution (only 1% of the energy is transported from the laser focal spot to an outer region of 2 mm size).

Random phase plates for beam smoothing on the Nova laser

1993 ◽  
Vol 32 (14) ◽  
pp. 2543 ◽  
Author(s):  
S. N. Dixit ◽  
I. M. Thomas ◽  
B. W. Woods ◽  
A. J. Morgan ◽  
M. A. Henesian ◽  
...  
Keyword(s):  
Random Phase ◽  
Phase Plates

scholarly journals Crossed beam energy transfer between optically smoothed laser beams in inhomogeneous plasmas

2020 ◽  
Vol 378 (2184) ◽  
pp. 20200038
Author(s):  
Stefan Hüller ◽  
Gaurav Raj ◽  
Mufei Luo ◽  
Wojciech Rozmus ◽  
Denis Pesme
Keyword(s):  
Energy Transfer ◽  
Inertial Confinement Fusion ◽  
Beam Energy ◽  
Random Phase ◽  
Intense Laser ◽  
Laser Beams ◽  
Band Width ◽  
Flow Profile ◽  
Smoothing Techniques ◽  
Spatio Temporal

Crossed beam energy transfer, CBET, in high-intensity laser–plasma interaction is investigated for the case of optically smoothed laser beams. In the two approaches to laser-driven inertial confinement fusion experiments, the direct-drive and the indirect-drive, CBET is of great importance because it governs the coupling of laser energy to the plasma. We use the two-dimensional wave-coupling code H armony to simulate the transfer between two laser beams with speckle structure that overlap in a plasma with an inhomogeneous flow profile. We compare the CBET dynamics for laser beams with spatial incoherence and with spatio-temporal incoherence; in particular we apply the smoothing techniques using random phase plates (RPPs) and smoothing by spectral dispersion (SSD), respectively. It is found that for laser beams (wavelength λ 0 ) with intensities ( I L ) above I L  ∼ 2 × 10 15  W cm −2 ( λ 0 /0.35 µm) −2 ( T e /keV), both the so-called plasma-induced smoothing as well as self-focusing in intense laser speckles induce temporal incoherence; the latter affects the CBET and the angular distribution of the light transmitted behind the zone of beam overlap. For RPP-smoothed incident beams, the resulting band width of the transmitted light can already be of the same order as the effective band width of the SSD available at major laser facilities. We examine the conditions when spatio-temporal smoothing techniques become efficient for CBET. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.

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