Optical diagnostics of laser-produced plasmas with ultra-short laser pulses

1980 ◽  
Vol 298 (1439) ◽  
pp. 407-414 ◽  
Keyword(s):  
Short Pulse ◽  
Laser Pulses ◽  
Laser Fusion ◽  
Light Pressure ◽  
Laser Plasma Interaction ◽  
Short Laser Pulses ◽  
Short Pulse Lasers ◽  
Pellet Density ◽  
Laser Heated ◽  
Interaction Problem

In laser fusion experiments the interesting phenomena occur on a picosecond timescale. Short-pulse lasers in combination with high resolution optics offer a powerful diagnostic tool. After a short description of the principles and experimental techniques I discuss three specific areas of the laser-plasma interaction problem, namely heat transport in the corona of a laser heated pellet, density profile steepening by light pressure and the generation of magnetic fields.

Compact Energy Measuring System for Short Pulse Lasers

2013 ◽  
Vol 20 (2) ◽  
pp. 183-190 ◽  
Author(s):  
A. Barna ◽  
I. B. Földes ◽  
Z. Gingl ◽  
R. Mingesz
Keyword(s):  
Short Pulse ◽  
Electronic Devices ◽  
Laser Pulses ◽  
Measuring System ◽  
Electric Response ◽  
Usb Interface ◽  
Radiated Noise ◽  
Fiber Optical ◽  
Measurement Control ◽  
Short Pulse Lasers

Abstract In experiments with short-pulse lasers the measurement control of the energy of the laser pulse is of crucial importance. Generally it is difficult to measure the amplitude of the pulses of short-pulse lasers using electronic devices, their response time being longer than the duration of the laser pulses. The electric response of the detector is still too fast to be directly digitized therefore a peak-hold unit can be used to allow data processing for the computer. In this paper we present a device which measures the energy of UV short (fs) pulses shot-byshot, digitizes and sends the data to the PC across an USB interface. The circuit is based on an analog peak detect and hold unit and the use of fiber optical coupling between the PC and the device provides a significant improvement to eliminate potential ground loops and to reduce conductive and radiated noise as well. The full development is open source and has been made available to download from our web page (http://www.noise.inf.u-szeged.hu/Instruments/PeakHold/).

Theoretical and experimental analysis of scan angle-depending pulse front tilt in optical systems for laser scanners

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Lasse Büsing ◽  
Tobias Bonhoff ◽  
Lars Behnke ◽  
Jochen Stollenwerk ◽  
Peter Loosen
Keyword(s):  
Experimental Analysis ◽  
Short Pulse ◽  
Laser Pulses ◽  
Industrial Applications ◽  
Optical Systems ◽  
Full Potential ◽  
Pulse Front ◽  
Laser Scanners ◽  
Short Laser Pulses ◽  
Ultra Short Pulse

AbstractFor realising fast and highly dynamical laser-based material processing, scanner systems are already utilised for many different industrial applications. Furthermore, ultra-short pulsed (<1 ps) laser sources provide possibilities of processing most different materials with highest accuracy. Owing to the large spectral bandwidth of ultra-short laser pulses, dispersion in optical components becomes relevant. The dispersion in optical systems for laser scanners may lead to scan angle-depending pulse properties as, for example, pulse front tilt. The investigation of these effects is not state of the art today but absolutely necessary to exploit the full potential of laser scanners for ultra-short pulse applications. By means of an exemplary focusing lens, the simulation and experimental analysis of scan angle-depending pulse front tilt is presented for the first time.

scholarly journals Simulations of energetic proton emission in laser–plasma interaction

2003 ◽  
Vol 21 (4) ◽  
pp. 573-581 ◽  
Author(s):  
LAURENT POMMIER ◽  
ERIK LEFEBVRE
Keyword(s):  
Laser Pulses ◽  
Hot Electrons ◽  
Rear Side ◽  
Laser Irradiance ◽  
Laser Plasma Interaction ◽  
Particle In Cell ◽  
Thin Foils ◽  
Short Laser Pulses ◽  
Additional Support ◽  
Density Scale

Energetic protons are emitted from thin foils irradiated by short laser pulses at high intensities. One- and two-dimensional particle-in-cell simulations have been used to study the influence of initial proton position, laser irradiance, and target density profile on this ion acceleration. These simulations bring additional support to the idea that protons are mainly accelerated from the rear side of the target, by electrostatic fields associated with hot electrons escaping into vacuum. The density scale length at the front of the target appears to be the main parameter to increase proton energies when the laser irradiance is fixed.

scholarly journals Accelerating ions with high-energy short laser pulses from submicrometer thick targets

2016 ◽  
Vol 4 ◽  
Author(s):  
F. Wagner ◽  
C. Brabetz ◽  
O. Deppert ◽  
M. Roth ◽  
T. Stöhlker ◽  
...  
Keyword(s):  
Focal Plane ◽  
Short Pulse ◽  
Laser Pulses ◽  
High Energy ◽  
Ion Acceleration ◽  
Temporal Contrast ◽  
Short Pulse Laser ◽  
Target Intensity ◽  
Short Laser Pulses ◽  
And Control

Using the example of the PHELIX high-energy short pulse laser we discuss the technical preconditions to investigate ion acceleration with submicrometer thick targets. We show how the temporal contrast of this system was improved to prevent pre-ionization of such targets on the nanosecond timescale. Furthermore the influence of typical fluctuations or uncertainties of the on-target intensity on ion acceleration experiments is discussed. We report how these uncertainties were reduced by improving the assessment and control of the on-shot intensity and by optimizing the positioning of the target into the focal plane. Finally we report on experimental results showing maximum proton energies in excess of 85 MeV for ion acceleration via the target normal sheath acceleration mechanism using target thicknesses on the order of one micrometer.

scholarly journals High-resolution X-ray spectroscopic diagnostics of laser-heated and ICF plasmas

1991 ◽  
Vol 9 (1) ◽  
pp. 3-48 ◽  
Author(s):  
A. A. Hauer ◽  
N. D. Delamater ◽  
Z. M. Koenig
Keyword(s):  
Laser Plasma ◽  
Measurement Techniques ◽  
Laser Fusion ◽  
X Ray ◽  
Laser Plasma Interaction ◽  
Basic Measurement ◽  
Modeling Techniques ◽  
Parameter Ranges ◽  
Laser Heated ◽  
Physical Phenomena

This article presents a review of X-ray spectroscopic diagnostic and measurement techniques as applied to laser plasma interaction and laser fusion studies. As a matter of definition we restrict our attention to the range of a several hundred eV to about 100 keV. We deal with both the basic measurement concepts and the instrumental techniques. First a brief review of the physical phenomena and parameter ranges involved is given. We then deal with specific X-ray spectroscopic instruments and methods that are useful in laser plasma X-ray spectroscopy. A discussion is given of various modeling techniques and how they can be compared with experimental measurements.

scholarly journals Physics of short pulse laser plasma interaction by multi-dimensional particle-in-cell simulations

1999 ◽  
Vol 17 (3) ◽  
pp. 571-578 ◽  
Author(s):  
A. PUKHOV ◽  
J. MEYER-TER-VEHN
Keyword(s):  
Short Pulse ◽  
Laser Pulses ◽  
Laser Plasma Interaction ◽  
Particle In Cell ◽  
Wake Field ◽  
Short Pulse Laser ◽  
Direct Laser ◽  
Underdense Plasmas ◽  
Laser Pulse Power ◽  
Overdense Plasma

Interaction of relativistically strong laser pulses with under- and overdense plasmas is studied by 3D particle-in-cell simulations. We show that electrons in the underdense plasmas can be accelerated not only by the plasma wake field, but also by direct laser push in self-generated magnetic and electrostatic fields. These two mechanisms of acceleration manifest themselves in the electron energy spectra as two effective “temperatures.” We show that the fast electrons transport a significant part of the laser pulse power through the overdense plasma in the form of magnetized jets. We also find high collective stopping because of an anomalous resistivity of the plasma.

scholarly journals Spatial extension of the electromagnetic field from tightly focused ultra-short laser pulses

2014 ◽  
Vol 32 (1) ◽  
pp. 89-97 ◽  
Author(s):  
L. Ionel ◽  
D. Ursescu
Keyword(s):  
Short Pulse ◽  
Laser Pulses ◽  
Measurement Point ◽  
Speed Of Light ◽  
Short Pulses ◽  
Spatial Extension ◽  
Rayleigh Range ◽  
Short Laser Pulses ◽  
The One ◽  
Ultra Short Pulse

AbstractIt is shown that in the focus of ultra-short pulses of duration t, the equivalent relation s = ct, where c is the speed of light and s the spatial extent of the pulse of the collimated pulse, does not hold. While the duration of one pulse is constant and independent of the measurement point, the spatial extension of the ultra-short pulse can be spatially shorter a factor more than 10 compared to the one obtained from the usual relation. The result is explained in correspondence with the extension of the Rayleigh range. Few femtosecond long gamma bursts can thus be generated in Thomson backscattering experiments performed in the lambda cube regime.

Investigation of Transient Signals in Nonuniform Media Based on Diffusion Approximation

2009 ◽  
Author(s):  
Sheng-gang Wang ◽  
Li-ming Ruan ◽  
Hong Qi ◽  
Xi-ying Wang ◽  
Bing-xi Li
Keyword(s):  
Optical Properties ◽  
Diffusion Approximation ◽  
Near Infrared ◽  
Short Pulse ◽  
Numerical Models ◽  
Optical Tomography ◽  
Laser Pulses ◽  
Biological Tissues ◽  
Infrared Light ◽  
Short Laser Pulses

With the development of the ultra-short laser technology, a new optical detection field based on the transient laser pulse signals will emerge in the future. Ultra-short laser pulses have been used in biological fields to obtain the optical properties of vivo tissues. There are many numerical models to simulate the propagation of short laser pulses in tissue medium. However, since most biological tissues show a high scattering and low absorption characteristics for near-infrared light, the most popular model is diffusion approximation method. Although with many limitations, its greatest advantage is higher computational efficiency. The propagation of short pulse laser in two dimension nonuniform medium is simulated based on the diffusion approximation model in present paper. The numerical method is validated by comparing the numerical results with the theoretical analysis results in semi-infinite uniform slab medium. Then diffusion approximation is used to simulate the transfer process of ultra-short pulses in two dimensional inhomogeneous medium. Finally, The influences of inclusions with different sizes and optical properties on time-resolved reflected signals are presented. This can help to choose suitable detection parameters in diffuse optical tomography.

scholarly journals Plasma channeling by multiple short-pulse lasers

2009 ◽  
Vol 27 (1) ◽  
pp. 109-114 ◽  
Author(s):  
W. Yu ◽  
L. Cao ◽  
M.Y. Yu ◽  
H. Cai ◽  
H. Xu ◽  
...  
Keyword(s):  
Ponderomotive Force ◽  
Laser Energy ◽  
Short Pulse ◽  
Laser Pulses ◽  
Particle In Cell ◽  
Peak Intensity ◽  
Cell Simulation ◽  
Short Pulse Lasers ◽  
Long Pulse ◽  
Similar Peak

AbstractChanneling by a train of laser pulses into homogeneous and inhomogeneous plasmas is studied using particle-in-cell simulation. When the pulse duration and the interval between the successive pulses are appropriate, the laser pulse train can channel into the plasma deeper than a single long-pulse laser of similar peak intensity and total energy. The increased penetration distance can be attributed to the repeated actions of the ponderomotive force, the continuous between-pulse channel lengthening by the inertially evacuating ions, and the suppression of laser-driven plasma instabilities by the intermittent laser-energy cut-offs.

scholarly journals Short pulse interaction experiments for fast ignitor applications

2000 ◽  
Vol 18 (3) ◽  
pp. 389-397 ◽  
Author(s):  
M. BORGHESI ◽  
A.J. MACKINNON ◽  
R. GAILLARD ◽  
G. MALKA ◽  
C. VICKERS ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Short Pulse ◽  
Laser Pulses ◽  
Inertial Confinement ◽  
Laser Plasma Interaction ◽  
Fast Ignitor ◽  
Underdense Plasmas ◽  
Confinement Fusion ◽  
Electron Propagation ◽  
Series Of Experiments

A detailed investigation of many aspects of the physics of laser–plasma interaction at very high laser intensities is required in order to assess the feasibility and the promise of the fast ignitor scheme for inertial confinement fusion. Relevant results, obtained in a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Centre d'Etudes Atomique, Limeil Valenton (France), are presented and discussed here. In particular, the formation of plasma channels was observed following the propagation of relativistically intense, ps laser pulses through underdense plasmas. The channels persist long after the interaction, and their expansion has been measured. Efficient guiding of ultraintense laser pulses, both through preformed density channels and through solid guides, has been demonstrated. Finally, indication of collimated fast electron propagation through solid targets has been obtained from the observation of filamentary ionization tracks in laser irradiated solid targets.

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