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Picosecond Plasma Radiation

#1183


Radiative Properties of Picosecond-Lazer-Produced Plasmas

Tech Area / Field

  • PHY-PLS/Plasma Physics/Physics

Status
3 Approved without Funding

Registration date
13.01.1998

Leading Institute
VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Supporting institutes

  • FIAN Lebedev, Russia, Moscow\nGNC VNII of Physical-Technical and Radiotechnical Measuremants, Russia, Moscow reg., Mendeleevo

Collaborators

  • CEA / DSM / DRECAM/CEN Saclay, France, Saclay\nKitasato University/School of Medicine / Physics Laboratory, Japan, Sagamihara\nLos-Alamos National Laboratory, USA, NM, Los-Alamos\nLawrence Livermore National Laboratory / University of California, USA, CA, Livermore\nRuhr Universität Bochum / Fakultaet für Physik und Astronomie Experimentalphysik insbe. Gaselektronik, Germany, Bochum

Project summary

Investigation of radiate properties of picosecond and subpicosecond laser-produced plasmas is an urgent problem nowadays due to significant progress in the activities aimed at development of high-brightness tabletop sources of X-ray radiation being run at a number of world laboratories using short-pulse laser facilities with relatively modest energy yield of several tenths to several tens Joules. In the last two years the use of these lasers to drive lasing plasmas has led to a considerable success in development of coherent X-ray radiation sources (laboratory X-ray lasers — XRL), as a real high-precision tool for fundamental research and practical applications in various fields of science, fine technologies, and medicine.

At the same time, the lack of knowledge on the fundamental processes in such plasmas appreciably bottlenecks experimental and theoretical studies of new, more efficient, methods to pump lasing plasmas, increase XRL energy yield, and further reduce the requirements to driver energy and, consequently, to its size and cost. This also impedes the development of new XRLs with shorter X-ray lasing wavelengths which could greatly improve current applications of X-ray technologies for high-resolution imaging, precision semiconductor micromachining, microlithography, microsurgery, diffractometry, studies of ultra-fast chemical reactions, and other applications.

The goal of the Project is to experimentally and theoretically investigate X-ray line radiation spectra from plasmas of solid targets driven by ultrashort high-intensity laser pulses. The main objective of these investigations is the retrieval of requisite information on the fundamental processes of ion-state ionization, excitation, and population inversion formation in such plasmas by using quantitative analysis of X-ray line radiation spectra from multielectron ions of low-Z and mid-Z elements, Z і 10; Z = 20-50, measured in the series of spectroscopic experiments both conducted previously and to be conducted under the Project.

Using experimental and technological facilities of VNIITF and VNIIFTRI, plasma radiation spectra generated from solid targets driven by ultra-short laser pulses of varied energy, width and contrast will be studied in detail. The experiments will be performed at VNIITF on the upgrade Nd:glass laser facility, utilizing the Chirped Pulse Amplification (CPA) technique and enabling to obtain picosecond-pulse intensities of up to 1017 W/cm2. Targets of different configurations will be considered to control the spatial and temporal parameters of expanding laser-produced plasmas and enhance the intensities of line radiation spectra.

High-luminosity X-ray spectrographs with unique spectral and spatial resolution developed by the Project participants will enable to register low-intensity X-ray spectra of multicharged ions in the wavelength range l = 2-20 A at resolution of l/Dl = 2000-15000 being a record one for this spectral range.

X-ray line radiation spectra will be quantified using automated processing of experimental data and solving an inverse problem of numerical reconstruction of registered spectra accounting for the actual experimental set-up. Calculations of line radiation spectra will be based on the radioactive hydro-modeling, level population kinetics, and formation of spectral line profiles by using the appropriate numerical models developed and being improved in the participating institutions of the Project.

The basic contractor of the proposed research work is RFNC-VNIITF, associate contractors are SRC VNIIFTRI and LPI.

A reliable basis for successful implementation of the proposed research is maintained by the present expertise and extensive experience at the participating institutions in the fields of


- experimental investigation of picosecond-laser-produced plasmas,
- X-ray plasma diagnostics with high spectral and spatial resolution,
- calculations of characteristics of fundamental processes in plasmas involving multi-charged ions, simulations of processes of short-pulse laser radiation absorption and acceleration of fast electrons,
- radiative hydro-modeling of laser-produced plasmas, level population kinetics and formation of line radiation spectra from multi-electron ions in plasmas

as well as by the research in the field of multicharged-ion plasma spectroscopy, which Project participants have been jointly pursuing for up to 10 years. Besides, practically all the leading experts of the proposed Project previously participated in closely-related ISTC Projects #076 "Atomic and Radiation Processes in Plasmas, Gases and Solids" and #107 "Generation of Ultra-Short Powerful Laser Pulses in Solid-State Lasers and their Employment for the Investigation of Superhigh-Intensity Radiation Interaction with Matter".

Currently, the participating institutions are pursuing the works on the improvement of existing experimental facilities and development of new models, codes, experimental-data processing tools, and high-resolution diagnostic equipment. Successful accomplishment of these activities at fairly modest expenses within the Project will allow to perform experimental studies of picosecond laser-produced plasmas from targets of various configurations at sufficient laser pulse intensities of up to 1017 W/cm2, improve accuracy of X-ray measurements by a factor of 5-10, thus, enabling to study in detail and model radiation spectra from plasmas heated with strong laser field.

Active joint activities and ongoing contacts with the scientific groups of foreign collaborators from USA, France, Germany, and Japan and other foreign scientists provide real capabilities to conduct joint research of novel structures and phenomena occurring in the ultrashort-pulse-driven plasmas like "hollow atoms" and "laser-induced satellites" using experimental data obtained at sub-picosecond facilities of foreign laboratories. This work attended by joint theoretical and numerical studies related to setting up the experiments and interpreting their results would provide deeper understanding of the radiative properties and fundamental processes investigated and thus enhance the experience of each scientific group.

Activities under the Project will result in considerable improvement of existing experimental techniques to register X-ray spectra from multicharged ions in plasmas driven by super-intensive laser pulses of ultrashort duration.

Wavelength measurements will be done along with the modeling of intensities of satellite-transition features responsible for the emission due to radiative decay of autoionizing states of multicharged ions which becomes dominant at the ultrashort-pulse laser interaction with condensed matter.

Theoretical models and simulation techniques will be improved enabling to perform large-scale simulations and numerical reconstruction of experimental spectra for the resonant lines in H-, He-, Li-, Ne-, Ni-like ions along with the groups of satellite transitions in the vicinity of these resonance lines — the features that usually tend to prevail in the radiation spectra of ultrashort-pulse-driven plasmas under investigation.

Detailed simulations of plasma line radiation spectra will enable to obtain fundamental information on the ionization processes in the matter and its resonant properties under the ultrashort action of powerful laser radiation as well as to investigate the techniques to create population inversion for the mid-Z Ne-like and Ni-like ion states in the collisionally pumped XRL schemes driven by the ultrashort laser pulses.

In the course of implementation of this Project, the basic goals pursued by the ISTC will be achieved to a large extent: the experts previously engaged in the activities related to the nuclear weapons research and development will be directly integrated into the international scientific community. The efforts of weapon specialists will be redirected to the peaceful scientific activities on the studies of radiative properties of picosecond laser-produced plasmas within the scope of the efforts of international scientific cooperation aimed at solution of extremely urgent scientific and technological problem — development of table-top source of coherent X-ray radiation for fundamental scientific research and practical applications in material science, fine technologies, chemistry and physics of surfaces, biology, and medicine.

Results of investigations pursued by the Project participants will be presented in the form of reports, joint publications in scientific journals and presentations at the scientific conferences.

Interested foreign scientists are welcomed to participate in the Project as foreign collaborators for the enhanced information exchange, participation in the joint scientific workshops, and promotive scientific cooperation in the related fields of research.


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