Capillary Plasma Discharge
Investigation of Dynamics of Powerful Capillary Discharge Plasma in the Medium of Gas and Metal Vapors
Tech Area / Field
- PHY-PLS/Plasma Physics/Physics
3 Approved without Funding
VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Fraunhofer Institut Lasertechnik, Germany, Aachen\nUniversity of Erlangen-Nurnberg / Department of Physics, Germany, Erlangen
Project summaryThe objective of the project is to investigate the hydrodynamics and radiation spectra of inert gases and metal vapours plasmas in powerful capillary discharges, created by current generators on the basis of inductive energy storages with wire and plasma switches. Typical values of currents in load fall into the range between 0.02 and 0.4 MA at increase rates from 1012 to 1013 A/s. For such conditions of capillary target loading there is proposed to investigate the forming and evolution of discharge over capillary wall internal surface depending on its geometry, wall materials and filling substances. The most interesting information is expected to be extracted form the measurements of X-radiation intensities in spectral range 0.02 – 2 keV.
Capillary discharge is considered at present as a perspective source of soft X-ray lasing in lines of Ne-like ions of middle-Z plasmas with wavelengths 500 – 200 A. J.Rocca in his experiments has already demonstrated the efficiency of Ne-like argon X-ray laser. We want both to reproduce his results and to investigate another possible laser mediums, such as Ti, Fe et al.
An experimental works require the support of one- and two-dimensional numerical simulation using magneto-hydrodynamics (MHD) and kinetics codes. The corresponding calculations will help to clear up the physics of atomic processes in discharge plasmas as well as the features of the experimental facilities operation with plasma switches and capillary discharge loads.
Experiments are planned to be accomplished using the small-size current generators SIGNAL and RAPID-M with inductive energy storage, plasma switch and fast capasitor bank GNUV, developed by VNIITF specialists – participants of the project. These generators can provide in load target one or two consecutive current pulses with peak values 0.02 – 0.4 MA and increase rates from 1012 to 1013 A/s. The first pulse (rather weak) in double-pulse loading regime could be used to evaporate the metal substances, coated on the internal capillary wall, with their subsequent transformation into plasmas under the powerful second one influence.
Available diagnostic techniques allow:
· to investigate dynamics of discharge spreading over the capillary wall internal surface and compression of formed current shell by recording radiation in visible range (optical streak camera);
· to determine total energy and time-integrated spectral distribution of continuum X-radiation part in the range between 0.1 and 5 keV (calorimeters, spectrometers with vacuum X-ray detectors);
· to measure output of some lines X-radiation in the range between 0.02 and 2 keV (gratings and crystal spectrograph);
· to carry out spatial and temporal measurements of X-radiation spectrum with quanta energies up to 10 keV (X-ray streak camera);
· to obtain one- and two-dimensional time-integrated images of plasma in its own radiation (pin-holes and emission tomography).
Listed techniques were already used in experiments with laser and Z-pinch plasmas.
As a main result of the project realization, the elaboration of effective methodology for creation of uniform along the discharge axis plasmas enabling to produce X-ray lasing could be considered. Different laser mediums and different regimes of their current loading should be investigated with the goal to optimize the X-radiation energy yield. This activity, as well, will lead to improvement and verification of diagnostic techniques and numerical simulation codes.
On the basis of proposed experimets results some conclusions about possibility to create the small-size X-ray laser facility, suitable for commercial applications, will be done.
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