RESUMEN
This work is devoted to the reconstruction of Z-pinch plasma emission spectra in the wavelength range of less than 10 Å recorded by using a crystal x-ray spectrograph at the Angara 5-1 mega-ampere facility. The spectrograph JA-1 used in experiments has a cylindrical mica crystal with dimensions of 50 × 40 mm2 and radius of curvature of 100 mm. Registration of spectra is performed on the photographic film UF-4 with dimensions of 30 × 10 mm2. To reconstruct the spectra, the previously developed method based on iterative approximation of a true spectrum shape while minimizing a residual between experimental and calculated spectrograms is used. The calculated spectrogram was obtained taking into account the instrumental function of the spectrograph. To define the instrumental function a virtual Monte-Carlo model in the Geant4 toolkit has been developed. This model takes into account the interaction of radiation with the mica crystal using dynamical theory of diffraction. A true spectrum of Z-pinch plasma radiation is reconstructed for a 16 mm high load made of two nested cylindrical wire liners. External liner with a diameter of 12 mm has 40 Al wires with a diameter of 18 µm. The internal liner with a diameter of 5 mm has 4 W wires with a diameter of 6 µm. The W wires have a sputtered layer of Re that is 0.5 µm thick.
RESUMEN
This work is devoted to the development of a method for the reconstruction of plasma extreme UV (EUV) spectra recorded by a three frame grazing incidence spectrograph (GIS-3D). The spectrograph provides registration of radiation reflected from the diffraction grating (DG) on a three-frame detector based on a microchannel plate with a scintillator screen and registration on a CCD camera, with an exposure time of one frame of â¼1.5 ns. DG has a gold-coated spherical concave form with a radius of curvature of 2 m and dimensions of 30 × 40 × 10 mm3. In this case, radiation is incident on the DG at a grazing angle of 2°; the DG period is 1.66 µm. The new single-pass method for the reconstruction of plasma EUV spectra was developed, which solves the inverse problem of decomposing experimental signals into separate contributions from each of the diffraction orders, followed by the reconstruction of the true plasma spectrum. Using the developed method, the possibility of finding a close approximation to the shape of a DG groove profile based on a priori information about the recorded spectra was demonstrated. In order to test and demonstrate the efficiency of this method, several experimental EUV spectra obtained at the Z-pinch facility Angara-5-1 with a current of â¼3-4 MA through loads made of either tungsten wires or polypropylene fibers were reconstructed. In addition, to test the single-pass method, the transmittance of EUV in cold aluminum was measured in the wavelength range of 3-35 nm, and it has a good match with the Henke database.
RESUMEN
In this work, the first proof of the principal of an in situ diagnostics of the heavy-ion beam intensity distribution in irradiation of solid targets is proposed. In this scheme, x-ray fluorescence that occurs in the interaction of heavy-ions with target atoms is used for imaging purposes. The x-ray conversion to optical radiation and a transport-system was developed, and its first test was performed in experiments at the Universal Linear Accelerator in Darmstadt, Germany. The Au-beam intensity distribution on thin foils and Cu-mesh targets was imaged using multiple x-ray pinholes (polychromatic imaging) and 2D monochromatic imaging of Cu Kα radiation by using a toroidally bent silicon crystal. The presented results are of importance for application in experiments on the investigation of the equation of states of high energy density matter using high intensity GeV/u heavy-ion beams of ≥1010 particles/100 ns.
RESUMEN
Ultra-intense MeV photon and neutron beams are indispensable tools in many research fields such as nuclear, atomic and material science as well as in medical and biophysical applications. For applications in laboratory nuclear astrophysics, neutron fluxes in excess of 1021 n/(cm2 s) are required. Such ultra-high fluxes are unattainable with existing conventional reactor- and accelerator-based facilities. Currently discussed concepts for generating high-flux neutron beams are based on ultra-high power multi-petawatt lasers operating around 1023 W/cm2 intensities. Here, we present an efficient concept for generating γ and neutron beams based on enhanced production of direct laser-accelerated electrons in relativistic laser interactions with a long-scale near critical density plasma at 1019 W/cm2 intensity. Experimental insights in the laser-driven generation of ultra-intense, well-directed multi-MeV beams of photons more than 1012 ph/sr and an ultra-high intense neutron source with greater than 6 × 1010 neutrons per shot are presented. More than 1.4% laser-to-gamma conversion efficiency above 10 MeV and 0.05% laser-to-neutron conversion efficiency were recorded, already at moderate relativistic laser intensities and ps pulse duration. This approach promises a strong boost of the diagnostic potential of existing kJ PW laser systems used for Inertial Confinement Fusion (ICF) research.