Radiating Plasma Liners
Study of Formation and Magnetic Compression of Plasma Liners Produced by Low Density Heterogeneous Substances
Tech Area / Field
- PHY-PLS/Plasma Physics/Physics
3 Approved without Funding
TRINITI, Russia, Moscow reg., Troitsk
- VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Sandia National Laboratories, USA, NM, Albuquerque\nForschungszentrum Karlsruhe Technik und Umwelt / Institut für Neutronenphysik und Reaktortechnik, Germany, Karlsruhe\nDepartment of the Navy / Naval Research Laboratory, USA, DC, Washington\nCNRS / Ecole Polytechnique, France, Palaiseau
Project summaryPresent day, fundamental and applied investigations using powerful x-ray sources with hv Ј 0.1 ё 1 keV are successfully developed in different directions. Investigations on superdense radiating plasma, fusion researches, x-ray spectroscopy, condensed matter equation of state may be mentioned.
One of the most effective ways of such sources production is the magnetic compression of cylinder liners that have been formed by plasma of high-Z ions in diodes of nanosecond generator with power і 1013 W and currents ~ 1ё 10 MA. At the final stage of liner implosion its kinetic energy transforms into thermal energy of plasma, being a powerful source of X-ray radiation. Experiments with composite liners are held on "ANGARA-5-1" installation (TRINITI). Different kinds of this scheme were investigated in joint experiments with SNL, LANL (USA), Ecole Polytechnique (France). On "PBFAz" installation (SNL, USA) more then 1 MJ of imploded liner energy was transformed into soft X-ray radiation. Nevertheless, in spite of impressive successes that were achieved in SNL, TRTNITI and other laboratories in US and Russia, many processes of noticeable influence on radiation pulse intensity and duration and on source geometry is still almost unexplored.
These processes are as follows:
- cylindrical shells - liner plasma formation out of initially cold substance;
- dynamics of compression and instability evolution of radiating plasma shell.
Study of above mentioned processes on the basis of parallel development of analytical and numerical methods and experiments at ANGARA-5-1 facility with liner currents up to 5.5 MA and generator pulse duration 90 ns is the goal of proposed project.
The process of "cold" liner transfer into plasma state and initial conditions effect on the liner plasma instabilities during implosion have to be investigated in the project. The main start factors are:
- the "cold" liner microstructure as a result of liner technology chosen;
- the "cold" liner shape;
- the liner substance initial ionization produced by auxiliary devises. The expected results are as follows:
1. New technologies of liner formation on the basis of low density foams of 1ё 10 mg/cm3 and micropowder clouds in vacuum will be designed.
2. Processes of low temperature substance transformation into plasma state will be investigated. The special attention will be paid to foam loads that represent themselves the 3-dimensional chaotic interlacing of filaments with submicron grains of radiating substance. At the same time existing approaches will be investigated and new approaches will be developed to form the initially azimuthally symmetrical shells formation by means of effect to plasma forming substance by plasma and/or radiation flows.
3. Initial conditions effect on instabilities that take place during liner compression will be studied.
4. Numerical calculations of multi - charged ion plasma dynamics in two-dimensional axial symmetry will be provided.
5. Systematic comparison of experiment, theory and calculation, recommendation on shell stability improvement and radiation intensity at the compression final phase will be made.
Investigations provision requires the solution of technical problems as follows:
- technology development for production the low-density liners of specified shape. Those liners are made of micro-cell foam with density of approximately 10-2 ё 10-3 of condensed phase one.
- methods of liner production on the micropowder clouds basis;
- development of diagnostic set for observations of liner breakdown and implosion process.
ANGARA-5-1 facility (TRINITI) will be the main experimental basis for proposing works. The facility is in operative regime and it is able to produce liner currents up to 4 ё 5.5 MA.
Diagnostic set will provide the measurement of liner shape dynamics in optic and x-ray ranges of plasma radiation, liner shadowgraphy pictures, density and temperature of liner's plasma.
Theoretical investigation will take place in TRINITI, RFNC-VNIITF.
The work will be completed with series of reports and publications on results of investigations.
The main expected results rather conventionally may be separated into two groups according to different stages of process under investigation as follows:
- plasma liner formation processes;
- plasma liner compression processes.
It is supposed that the data on the initial stage of the process will include investigations of liner azimuth current distribution during current shell formation and determination of factors that govern the azimuth homogeneity of the current (percentage of initial ionization, foam liner structure etc.) In investigations of the initial stage of the process the special attention will be paid to liner substance transformation into plasma state. Using the diagnostics with time resolution Ј 0.5 ns will allow to come to conclusion about electron conductivity, temperature and density dynamics at the plasma liner formation stage.
The expected results may be as follows:
- identification of types of instabilities that takes place during liner compression and determination of factors that influent on their evolution.
- determination of liner parameters that is necessary to provide for the effective compression (geometric characteristics, material's types, initial conditions etc.) Developments of technologies for foam and micropowder liner producing plasma shell with specific density distribution, diagnostics for liner dynamic and liner parameters measurements and programs for calculation modeling of processes both at the initial stage of current shell formation and liner compression stage processes may be expected as the results of the work.
Potential role of foreign collaborators
Foreign collaborators could participate in this project by means of joint discussion of investigation results, mutual exchange of diagnostics methods and technologies, coordination of experimental programs on different installations. There is agreement to be collaborator of this Project from Dr. Bernard Etlicher, Ecole Polytechnique, France.
Also there is preliminary agreement to be collaborator from Dr. Dillon McDaniel, National Laboratory Sandia, USA.
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