This paper presents the investigation results on light absorption of silica optical fibers under effect of gamma-quanta with the energy of 2.5 MeV. Exposure radiation doses were 100-300 R, gamma-quanta had the energy of similar to 13.5 MeV with the exposure radiation dose of 20-40 kR. Influence of the electron beam having the energy of 2.5 MeV at absorbed dose up to similar to 200 krad at rise time up to similar to 1013 rad/s, and pulselength tau(1/2)-20 ns in the wavelength range from 0.53 to 1.30 mu m was also studied. This paper describes investigation of the fibers with pure silica cores and the silica cores with different dopants. One could observe difference in behavior of the fibers absorption at exposure dose of 40 kR and absorbed dose of 200 krad. Increasing the light wavelength from 0.53 to 1.3 mu m, we observed the decrease of the optical absorption that was caused by radiation exposure for all studied fiber samples. We also studied optical characteristics of a single-mode fiber (pure SiO2 core and F doped cladding) fabricated using low-birefringence technology. One can also see that radiation exposure did not cause depolarization of the linearly polarized light and did not result to polarization plane angle change for the specified fiber. This allows using of the specified fiber as the fiber-optical probe for current (tens of megamperes) and magnetic field (tens of megagauss) measurements in the conditions of high-power radiation exposure. The presented results allow selecting of the optimum light wavelength and composition of the dopants for the fibers in order to minimize the optical losses.

Radiation-induced attenuation (RIA) in fibers is investigated at lambda= 1.55 mu m due to pulsed bremsstrahlung irradiation from an electron accelerator (mean photon energy of similar to 5MeV, pulse duration of similar to 20 ns, doses of similar to 3-76 Gy, time scale of similar to 10(-9) to 5 x 10(-2) s). The fibers studied include three Ge-doped-silica-core fibers of different design and an undoped-silica-core fiber. The latter has been fabricated by an optimized technology to virtually fully suppress self-trapped holes and chlorine-associated RIA. RIA in Ge-doped fibers is found to increase with dose sublinearly with the power-law exponent in the range 0.69-0.96, although insufficient statistics (2-3 measurements for a fiber) do not allow us to state this with much confidence. The lowest RIA upon irradiation with high pulse doses (> 20 Gy) is demonstrated by the undoped fiber; however, this RIA proved to be greater than that in a hollow-core photonic crystal fibers studied elsewhere. At smaller doses, RIA in the undoped fiber is estimated to amount just to a few dB/km at times 10(-3) - 10(-2) s. Therefore, optimized undoped fibers are argued to be the best-suited all-solid fiber type for practical applications under pulsed irradiation and combined pulsed and steady-state irradiations.

One of the perspective directions in high-energy-density physics is the creation of powerful electro physical facilities capable to form megampere current pulses with short front. This paper presents test results of the device based on five-element disk magnetocumulative generator DMCG480 and an explosive current opening switch. The current pulse of 15 MA with characteristic rise time of similar to 0.8 mu s was obtained in the equivalent multiwire array load of 17 nH at circuit breaking with the current of 32 MA.

This paper presents the results of tests of a facility based on a ten-element disk magnetocumulative generator and an explosive opening switch. A current of 10 MA with a characteristic rise time of ≈0.5 µs was obtained by breaking a circuit with a current of 18 MA in a load with an inductance of 16 nH, which is equivalent to the inductance of the chamber with a multiwire liner.

The paper presents optical probes to measure currents of tens megamperes and megagauss magnetic fields of ~10 MGs. Operating principle of the probes is based on the Faraday effect. Investigation results on determination of optical losses appearing at fibers alloyed with different dopants in a core under influence of an ionizing radiation at its rise time up to 1013 R\s are described in the paper. The least optical losses have been observed in the fibers of POD type. The core of this fiber is made of pure quartz, and the shell is alloyed with fluorine. Optical spectrum range of the least optical losses is ~(1.0...1.3) μm. We did not observe light depolarization at radiation effect on the POD type fiber with small LB (low-birefringence), i.e. general light intensity attenuation without disturbance of its linear polarization takes place. Such fiber could be used as the optical probes to record the currents of tens megamperes at rise time of ≤ 100 ns in the conditions of radiation influence on the fiber with exposition dose increase rate up to 1013 R/s.

Summary form only given. The paper presents investigation results on development of soft X-ray radiation sources based on imploding multi-wire Z-pinches, powered from magneto-cumulative generators. Parameters of the source, realized with fast helical magneto-cumulative generator MCG-200, are close to calculation results: an energy of the X-ray radiation is 180 kJ in a pulse with the width at half height of ~20 ns, the pinch plasma temperature is 65 eV, a current amplitude in the liner load is 5.3 MA at a rise time of 400 ns. The research on optimization of the X-ray radiation source parameters with the power source based on the magneto-cumulative generator of 240 mm diameter are being continued. Up to now the current of 14 MA amplitude and rise time of 1.3 mus could be supplied into the liner load . A length of the generated pulse of the X-ray radiation is 60 ns at half height, the pinch plasma temperature is ~60 eV.

Summry form only given. Investigations on determination of a transmission factor of quartz fibers at their irradiation with a high-power pulse of an ionizing radiation are carried out. Length of an x-ray pulse is ~10 ns. The measurements were carried out with several wavelengths of a sounding light radiation of 0.68 mum, 0.82 mum, 0.94 mum. Light absorption factors are determined depending on the x-ray radiation doze, the wavelength of the sounding light radiation and a composition of alloy additions. The investigations showed that the absorption factor value decreases with increase of the wavelength of the laser radiation.

Results are presented from experiments on the implosion of wire arrays powered from 100-and 200-mm-diameter helical explosive magnetocumulative generators with explosive opening switches. The experiments were performed at load currents of up to 4 MA, the current rise time being 0.3–0.4 μs. The maximum soft X-ray yield of ∼ 100 kJ was achieved at a pinch plasma temperature of 55 eV. A two-dimensional MHD code was developed to simulate the process of liner implosion and the generation of X-ray emission. The results of computer simulations agree satisfactorily with the experimental data.

Experimental results on powering of a single-turn solenoid with a current of ~3 MA with a rise time of ~0.5 mus from a helical magneto-cumulative generator of 100 mm diameter (MCG-100) having explosive current opening switch are presented. To protect the solenoid from destruction with HE-charge explosion products, it was located behind an armored plate. The magnetic field in the solenoid was ~300 T. Experimental results showed possibility of single-turn solenoids powering, used for investigation of samples behavior in ultra-high magnetic fields, from MCG-100, having the opening switch, and possibility of the samples preservation after the experiments.

Investigation results of current pulse sharpening of multi-element disk generator with HE-charge diameter of 240 mm with electric exploded opening switch are presented. Both solid conductor (copper foil), and layer structure metal-dielectric were used in electric-exploded opening switch. Experimental results with three-element generator showed the possibility to form the current pulse of ~30 MA with characteristic rise time of ~1 mus in the load of ~1.5 nH. It is supposed to use ten-element generator with electric exploded opening switch as an energy source in EMIR complex for soft x-ray radiation generation at multi-wire liner implosion.

For future research in the area of thermonuclear fusion and physics of high-energy-density VNIIEF is conducting the development of the multifunctional electrophysical explosive complex "EMIR". It is supposed, that with the use of this complex the conditions of thermonuclear ignition in high temperature plasma (/spl sim/0.3 keV) with a lifetime about several nanoseconds, forming during the electrodynamic compression of cylindrical plasma shells in Z-pinch geometry, will be achieved. One of the main problems to be resolved for realization broad-scale experiments on the complex "EMIR" are the development of methods for diagnostics of the processes, taking place in its separate devices. Along with the development of the methods intended to measure electrotechnical parameters of the magnetic energy source modules the development of methods for radiation diagnostics of plasma load and cavity with the thermonuclear target is of primary importance. In the report the measurement methods of the main power module parameters, including plasma current breaking, systems of the soft X-ray generation and the thermonuclear target are considered. The sensitivity and resolution of the methods are pointed out. The proposed measurement methods are adapted to conditions of explosive experiments with increased level of electromagnetic noise and may be tested on different laboratory installations. The realization of experiments with such methods will promote the obtaining of important information about dynamics of processes, which take place in the multifunctional electrophysical explosive complex "EMIR".