Irradiation of a low-density sphere target with a pinch x-ray source of a quasi-spherical array at the Angara 5-1 facility

Experiments on three-dimensional implosion of quasi-spherical arrays at discharge currents up to 4 MA were conducted on the Angara-5-1 facility. The effect of plasma flows and radiation from a quasi-spherical array on a test spherical target made of agar-agar foam [(C14H18O9)n] located in the center of the array was studied. In the case of the linear mass distribution of tungsten wires of the quasi-spherical array in the form ml(θ) ∼ sin−1 θ, plasma formation ends synchronously along the length of the wires. As a result, the plasma of the quasi-spherical array effectively interacts with the test target. Plasma flows and radiation from the quasi-spherical array form a brightly glowing annular zone—the radiation shock wave (RSW) region—within the test target volume. X-ray frame images were used to record the dynamics of the RSW region propagation within the target: initially, a decrease in the RSW size followed by an increase, up to the initial diameter of the test target. The average rate of decrease and subsequent increase in the RSW radius reached vRSW ∼ (5–8) × 106 cm/s. Laser shadowgraphy data were used to obtain data on the state of the test target at the stage of the prolonged ablation period of the quasi-spherical array, when a compact cloud of radiating plasma forms around the target due to the arrival of a current precursor. At this stage, the plasma layer thickness on the target surface increases from 0.1 to 0.4 mm. Spectral data demonstrated a shift of the spectrum maximum to the short-wavelength region (38–52 Å) at peak radiation power. Experimental data on the spectral transmission of the test target material were obtained.