Diagnostics of fast processes in laser plasmas after the irradiation of low-density media in the mishen facility

New experimental data on the laser irradiation of low-density porous materials in the Mishen facility are presented and discussed. A wide set of optical and X-ray diagnostics was used to analyze the physical processes in porous media with different microstructures and specific densities of 1–30 mg/cm³ exposed to laser pulses with λ=1.054 µm, τ=3 ns, and I=10¹³–10¹⁴ W/cm². The features of laser absorption and scattering and the processes of energy transfer in porous media were investigated for different average densities, thicknesses, and microstructures of the targets and different incidence angles of the laser beam. It was found that the material microstructure (chaotic or quasi-ordered) significantly affected the formation and dynamics of a plasma produced inside the irradiated samples that model the components of the advanced targets used in inertial confinement fusion research.     

Experimental and theoretical studies of the physical processes occurring in thin plane targets irradiated by intense X-ray pulses

Results are presented from experimental and theoretical studies of the interaction of intense X-ray pulses with different types of plane targets, including low-density (～10 mg/cm³) ones, in the Angara-5-1 facility. It is found experimentally that a dense low-temperature plasma forms on the target surface before the arrival of the main heating X-ray pulse. It is demonstrated that the contrast of the X-ray pulse can be increased by placing a thin organic film between the target and the discharge gap. The expansion velocity of the plasma created on the target surface irradiated by Z-pinch-produced X rays was found to be (3–4) × 10⁶ cm/s. A comparison between the simulation and experimental results confirms the validity of the physical-mathematical model used.     

The isolation and characterization of lipopolysaccharide-defective mutants of Pseudomonas aeruginosa PAC1.

Mutants with defective lipopolysaccharides (LPSs) were isolated from Pseudomonas aeruginosa PACIR (Habs serogroup 3) by selection for resistance to aeruginocin from P. aeruginosa PI6 Carbenicillin-sensitive mutants were isolated from P. aeruginosa PACI but not all had defective LPSs. Rough colonial morphology and resistance to bacteriophage II9X appeared to be independent of LPS composition. The LPSs from five mutants were analysed and compared with that of the parent strain. Separation of partially-degraded polysaccharides from LPS from PACI on Sephadex G75 yielded two different high molecular weight fractions and a phosphorylated low molecular weight fraction (L). The mutant LPSs lacked most or all of the high molecular weight fractions but retained some low molecular weight material. That from PACI and two of the mutants was separated by elution from Biogel P6 into two fractions. One, L2, was the core polysaccharide while the other, LI, contained short antigenic side-chains attached to the core like the semi-rough (SR) LPSs of the Enterobacteriaceae. The two mutants which gave the LI fraction with Habs 3 and PACI antisera as did the parent strain. The other three mutants were unreactive and their LPSs contained core components only. One appeared to have a complete core while the other two lacked rhamnose and rhammose plus glucose respectively. Thus there may be four types of LPS in PACI: one contains unsubstituted core polysaccharide and yields L2 on acid hydrolysis, another has short antigenic side-chains of the SR type and yields the LI fraction, while the two high molecular weight fractions are derived from core polysaccharides with different side-chains.