Generation of an extremely stable light bullets in a preformed plasma near critical density has been observed experimentally. Optical probing measurements indicate the formation of pulsating channels, typically of about 5 micrometers in diameter, directed towards a heating laser beam, as well as a disconnected massive plasm block moving also towards a laser beam.
{"title":"Experimental investigation of light bullets generated by interaction of intense picosecond laser pulses with plasma","authors":"N. Vogel, N. Kochan","doi":"10.1117/12.425564","DOIUrl":"https://doi.org/10.1117/12.425564","url":null,"abstract":"Generation of an extremely stable light bullets in a preformed plasma near critical density has been observed experimentally. Optical probing measurements indicate the formation of pulsating channels, typically of about 5 micrometers in diameter, directed towards a heating laser beam, as well as a disconnected massive plasm block moving also towards a laser beam.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"4424 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129823685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. G. Borodin, A. V. Charukchev, V. N. Chernov, O. N. Gilev, A. L. Zapysov, V. V. Il'in, V. M. Komarov, V. A. Malinov, V. M. Migel, N. V. Nikitin, V. Saprikin
The interaction of a 1053 nm picosecond laser pulse with a solid target for focused intensities of up to 1019 W/cm2 are studied by measurements of the absorption of the laser light in the plasma and by measurements of the production of hard x-rays. Absorption measurements are made by collecting the scattered light in set of calorimeters. Light scattered in backward and specular directions is collected separately. Measurements are presented for both high and low Z targets. Hard x-ray spectrum in range 15-1000 keV and hot electron production in range 1-22 MeV are measured using a multichannel filter/scintillator and filter/semiconductor spectrometers. Spatial parameters of fast ions are studied.
{"title":"Absorption and transformation of laser energy in picosecond laser-plasma experiments at intensity of 1016 to 1019 W/cm2","authors":"V. G. Borodin, A. V. Charukchev, V. N. Chernov, O. N. Gilev, A. L. Zapysov, V. V. Il'in, V. M. Komarov, V. A. Malinov, V. M. Migel, N. V. Nikitin, V. Saprikin","doi":"10.1117/12.425636","DOIUrl":"https://doi.org/10.1117/12.425636","url":null,"abstract":"The interaction of a 1053 nm picosecond laser pulse with a solid target for focused intensities of up to 1019 W/cm2 are studied by measurements of the absorption of the laser light in the plasma and by measurements of the production of hard x-rays. Absorption measurements are made by collecting the scattered light in set of calorimeters. Light scattered in backward and specular directions is collected separately. Measurements are presented for both high and low Z targets. Hard x-ray spectrum in range 15-1000 keV and hot electron production in range 1-22 MeV are measured using a multichannel filter/scintillator and filter/semiconductor spectrometers. Spatial parameters of fast ions are studied.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128321681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Hora, R. Castillo, W. Chan, M. Collins, T. Stait-Gardner
Laser generated electron-positron pair production is under discussion in the literature form 1969 and large numbers of positrons have been measured since a few years. For electron-positron pair production in vacuum due to vacuum polarization as predicted by Heisenberg 1934, again much higher laser intensities around 1028W/cm2 are necessary which may be available within a number of years. For these cases the similar electron acceleration by gravitation near black holes at Hawking-Unruh radiation have been discussed since 1985 by McDonald. These conditions are considered in view of the earlier work on pair production, change of statistics for electrons at relativistic black body radiation and an Einstein-recoil mechanism with a consequence of a physical foundation of the fine structure constant.
{"title":"Laser-produced pair production in vacuum and Hawking-Unruh radiation","authors":"H. Hora, R. Castillo, W. Chan, M. Collins, T. Stait-Gardner","doi":"10.1117/12.425550","DOIUrl":"https://doi.org/10.1117/12.425550","url":null,"abstract":"Laser generated electron-positron pair production is under discussion in the literature form 1969 and large numbers of positrons have been measured since a few years. For electron-positron pair production in vacuum due to vacuum polarization as predicted by Heisenberg 1934, again much higher laser intensities around 1028W/cm2 are necessary which may be available within a number of years. For these cases the similar electron acceleration by gravitation near black holes at Hawking-Unruh radiation have been discussed since 1985 by McDonald. These conditions are considered in view of the earlier work on pair production, change of statistics for electrons at relativistic black body radiation and an Einstein-recoil mechanism with a consequence of a physical foundation of the fine structure constant.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"4424 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130413591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anomalous absorption of an intense short laser pulse in overdense plasmas is analyzed. A diffusion equation describing the time evolution of the electron distribution function is derived. From the equation it is shown that the electron distribution function becomes anisotropic in the momentum space, which gives rise to the absorption of the energy. The diffusion is dominant in px direction rather than pz direction. In pz direction, however, the drift term is contained resulting for the longitudinal component of the J X B force, which has ben neglected but is important for the intense laser case. The absorption coefficient and skin depth is obtained for the ASE regime. The absorption coefficient increases in time starting from the well-known absorption coefficient for a lower intensity laser pulse.
{"title":"Anomalous absorption of linearly polarized laser pulse in overdense plasma","authors":"Tatsufumi Nakamura, S. Kato, Toshikazu Kato","doi":"10.1117/12.425614","DOIUrl":"https://doi.org/10.1117/12.425614","url":null,"abstract":"Anomalous absorption of an intense short laser pulse in overdense plasmas is analyzed. A diffusion equation describing the time evolution of the electron distribution function is derived. From the equation it is shown that the electron distribution function becomes anisotropic in the momentum space, which gives rise to the absorption of the energy. The diffusion is dominant in px direction rather than pz direction. In pz direction, however, the drift term is contained resulting for the longitudinal component of the J X B force, which has ben neglected but is important for the intense laser case. The absorption coefficient and skin depth is obtained for the ASE regime. The absorption coefficient increases in time starting from the well-known absorption coefficient for a lower intensity laser pulse.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"289 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116206642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Line x-ray emission from short-pulse laser-produced plasmas is studied via 1D and 2D hydrodynamics models coupled with planar atomic physics post-processor. Laser energy conversion efficiency to He-(alpha) line emission is shown to be significantly enhanced when laser prepulse precedes the main pulse at an optimum pulse separation. The calculated optimum pulse separation of 1.5-2 ns as well as emitted energy and spectra compare well with the experiment.
{"title":"Simulation study of short-pulse laser energy conversion to x-ray line emission","authors":"J. Limpouch, A. Iskakov, A. Andreev, H. Nakano","doi":"10.1117/12.425554","DOIUrl":"https://doi.org/10.1117/12.425554","url":null,"abstract":"Line x-ray emission from short-pulse laser-produced plasmas is studied via 1D and 2D hydrodynamics models coupled with planar atomic physics post-processor. Laser energy conversion efficiency to He-(alpha) line emission is shown to be significantly enhanced when laser prepulse precedes the main pulse at an optimum pulse separation. The calculated optimum pulse separation of 1.5-2 ns as well as emitted energy and spectra compare well with the experiment.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121629717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An understanding of hydrodynamics instability development is a key element in the studies of the ICF target robustness. All the perspective target design proposals are close to a limit when these instabilities leave out an ignition. It concerns both a direct and an indirect drive design. SO, the evaluation of the perturbation amplitudes of the mixing zone size is the principal ones. At the present work the basic ideas to predict the scales of a turbulent mixing in the laser targets are formulated. These ideas are based on the knowledge of the individual perturbation development and a co-evolution of a set of such the perturbation.This approach is different from a standard harmonic analysis, it takes into account a character of a geometry and it is based in the numerical and experimental results of the hydrodynamics instabilities investigations.
{"title":"Hydrodynamic instabilities and turbulent mixing at the laser target compression","authors":"V. Rozanov, N. Zmitrenko","doi":"10.1117/12.425631","DOIUrl":"https://doi.org/10.1117/12.425631","url":null,"abstract":"An understanding of hydrodynamics instability development is a key element in the studies of the ICF target robustness. All the perspective target design proposals are close to a limit when these instabilities leave out an ignition. It concerns both a direct and an indirect drive design. SO, the evaluation of the perturbation amplitudes of the mixing zone size is the principal ones. At the present work the basic ideas to predict the scales of a turbulent mixing in the laser targets are formulated. These ideas are based on the knowledge of the individual perturbation development and a co-evolution of a set of such the perturbation.This approach is different from a standard harmonic analysis, it takes into account a character of a geometry and it is based in the numerical and experimental results of the hydrodynamics instabilities investigations.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127590354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Caruso, S. Gus'kov, I. Y. Doskach, N. Zmitrenko, V. Rozanov, C. Strangio
The processes of the weak shock wave generation and propagation in the solid targets are studied by analytical and numerical methods. The impact of the laser pulse with wavelength (lambda) equals 1.06 micrometers and the pulse intensity I equals 1010-1012W/cm2 was considered as a wave source. The resulting wave with pressure about 1-100kBar is studied in a solid medium 0.5-1 mm thick. The results of modeling compared with experimental data shows correctness of hydrodynamical approximations for a given problem.
{"title":"Laser-generated weak shock wave propagation dynamics in the solids","authors":"A. Caruso, S. Gus'kov, I. Y. Doskach, N. Zmitrenko, V. Rozanov, C. Strangio","doi":"10.1117/12.425544","DOIUrl":"https://doi.org/10.1117/12.425544","url":null,"abstract":"The processes of the weak shock wave generation and propagation in the solid targets are studied by analytical and numerical methods. The impact of the laser pulse with wavelength (lambda) equals 1.06 micrometers and the pulse intensity I equals 1010-1012W/cm2 was considered as a wave source. The resulting wave with pressure about 1-100kBar is studied in a solid medium 0.5-1 mm thick. The results of modeling compared with experimental data shows correctness of hydrodynamical approximations for a given problem.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126477042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose to use nondegenerate cascaded four-wave mixing processes for efficient high order harmonic generation in plasmas and dielectrics. A simple model is used to estimate the temporal duration and maximum order of the generated harmonics for both a typical laser-produced plasma and glass slide. In the plasma case, we expect considerable pulse compression, with the production of sub-femtosecond pulses starting from the 8th harmonic.
{"title":"Application of highly nondegenerate cascaded four-wave mixing to high-order harmonic generation","authors":"H. Crespo, J. T. Mendonça, A. Guerreiro","doi":"10.1117/12.425542","DOIUrl":"https://doi.org/10.1117/12.425542","url":null,"abstract":"We propose to use nondegenerate cascaded four-wave mixing processes for efficient high order harmonic generation in plasmas and dielectrics. A simple model is used to estimate the temporal duration and maximum order of the generated harmonics for both a typical laser-produced plasma and glass slide. In the plasma case, we expect considerable pulse compression, with the production of sub-femtosecond pulses starting from the 8th harmonic.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121783523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Kalal, M. Vrbova, A. Jancarek, J. Limpouch, L. Pína, M. Šiňor, P. Vrba, L. Drska, L. Nadvornikova
In this paper our new capillary discharge device built for the soft x-ray laser studies is described and the first experimental results obtained from electrical, optical and UV diagnostics together with code simulations are presented.
{"title":"Optical diagnostics of evacuated polyacetal capillary discharge","authors":"M. Kalal, M. Vrbova, A. Jancarek, J. Limpouch, L. Pína, M. Šiňor, P. Vrba, L. Drska, L. Nadvornikova","doi":"10.1117/12.425552","DOIUrl":"https://doi.org/10.1117/12.425552","url":null,"abstract":"In this paper our new capillary discharge device built for the soft x-ray laser studies is described and the first experimental results obtained from electrical, optical and UV diagnostics together with code simulations are presented.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"126 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130225156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Thompson, S. Rothman, A. Evans, R. Eagleton, D. Hoarty, S. J. Davidson, C. Robinson, J. Maw, P. Graham
The AWE 1 TW Nd-glass laser HELEN has been used for a number of studies of material properties. Here we discuss measurement of preheat in our high pressure Hugoniot studies and present results for the principal Hugoniot of triacrylate foam at pressures up to 1 Mb. Michelson interferometer results demonstrate spallation in shocked aluminum enabling us to quantify the spall thickness and strength. High resolution spectral data has been obtained from niobium samples in which the M-shell approaches full occupancy.
{"title":"Material properties experiments using the AWE HELEN laser","authors":"P. Thompson, S. Rothman, A. Evans, R. Eagleton, D. Hoarty, S. J. Davidson, C. Robinson, J. Maw, P. Graham","doi":"10.1117/12.425563","DOIUrl":"https://doi.org/10.1117/12.425563","url":null,"abstract":"The AWE 1 TW Nd-glass laser HELEN has been used for a number of studies of material properties. Here we discuss measurement of preheat in our high pressure Hugoniot studies and present results for the principal Hugoniot of triacrylate foam at pressures up to 1 Mb. Michelson interferometer results demonstrate spallation in shocked aluminum enabling us to quantify the spall thickness and strength. High resolution spectral data has been obtained from niobium samples in which the M-shell approaches full occupancy.","PeriodicalId":340981,"journal":{"name":"European Conference on Laser Interaction with Matter","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122114485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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