Pure-silica-core F-doped-silica cladding fiber ("pure silica fiber", PSF) is subjected to eight pulsed-X-ray irradiations (pulse duration of 20 ns, mean photon energy of similar to 5 MeV). In each pulse, the probe light power at the wavelength lambda = 1.55 mu m is either 10 mW, or 33-40 mu W, the irradiation temperature being also varied among pulses from -80 to +85 degrees C. Post-pulse decay of radiation-induced absorption (RIA) in the PSF is measured at lambda = 1.55 mu m in the subsecond scale and, in four typical cases, is approximated in the framework of the second order -kinetic model to separate RIA due to inherent and strain-assisted self-trapped holes (STHs). Post-pulse RIA time evolution is found to be qualitatively different at the different probe light powers. At the 33-40-mu W power, RIA is virtually wholly described by inherent STHs with some admixture of strain-assisted ones only at the highest temperature of + 85 degrees C. At the 10-mW power, the RIA temporal run is found to be composed of two clear-cut successive domains due to inherent and strain-assisted STHs regardless of temperature. An enhanced probe light power and enhanced temperature are found to have a similar influence on the STHs of the two classes: they partly suppress the inherent STHs and promote the occurrence of the strain-assisted ones. A physical mechanism is proposed for the latter effect. Basic principles for selecting the best-suited probe light power at lambda = 1.55 mu m with regard to the application specifications are proposed.

This paper describes different types of modern magneto-cumulative generators (MCGs), their operating principles, design, and main characteristics. Application areas of the generators for fundamental and applied studies in high energy density physics are considered. Some investigation results are presented. Prospects for the further development of the MCG facilities are discussed.

Radiation-induced attenuation (RIA) is investigated in pure-silica-core optical fibers (PSFs) upon their pulsed-X-ray irradiation. RIA at small post-pulse times (t <= 0.001-0.1 s) is argued to be mainly due to inherent self-trapped holes (STHs), whereas at large times, due to strain-assisted STHs, as shown by Girard et al. Significant suppression of inherent STHs is found to occur in PSFs upon pulsed pre-irradiation with a dose of just similar to 100-200 Gy. Thus, a radiation-hardening effect is revealed for the first time, which is of practical value for PSFs to be exposed to pulsed irradiation. Fiber drawing temperature T-d is found to have an essential effect on RIA upon pulsed irradiation. The optimal T-d values are estimated for PSF applications at small (t < 0.01 s) and large (t > 0.01 s) post-pulse times.

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.

The effect of strong pulsed magnetic fields on gas adsorption at dielectric surfaces is demonstrated. We describe the experimental technique and the results indicating a considerable increase in the surface concentration of the adsorbed substance under the action of pulsed magnetic fields with an induction amplitude up to 50 T. The increase in the lifetime and stability of the adsorbed layer is observed. It is shown that the effect of magnetically induced sorption is also manifested in the interaction of iodine vapor with the surface of dielectrics.

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 development of new sorbents and methods of their catalytic activity increase is an important task of nuclear energy and medicine. This paper presents the investigation results on the magnetic field effect on the iodine adsorption on the polyethylene, polycarbonate, and polystyrene surfaces. The revealed effect of the sorption property improvement by the dielectric surfaces in the magnetic fields opens new possibilities for efficiency increase of radioactive materials filters. The novel technology of medical polymer modification could be developed on the basis of magneto-induced sorption effect. The goal of this technology is to decrease biodegradation degree, acquire bactericidal and antiviral properties, increase cytoreduction, and purposefully change the mechanical characteristics.

The differential magnetization of LaCoO3 in magnetic fields of up to 500 T has been measured at a temperature of 4.2 K. The magnetization curve reveals several features which suggest a complex pattern of the transition of LaCoO3 from the low-spin state to the high-spin state. The magnetic moment starts to grow in fields above 50 T to reach a plateau in the 130–240-T region, after which the magnetic moment continues to rise up to saturation in fields ∼500 T.

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.

The history of the achievements of the All-Russian Research Institute of Experimental Physics (VNIIEF in Russ. abbr. )i n the field of ultrahigh magnetic field (UHMF) generation and applications in fundamental physical studies begins in 1952, when Andrey D Sakharov put forward the idea of magnetic cumulation as one of the possible methods for achieving a controlled thermonuclear reaction [1]. He also proposed two types of magnetocumulative generators of UHMFs (MC-1) and energy (MC-2) [1, 2]. In the first of them, a special device produces the initial axial magnetic field flux in the cavity of a cylindrical metal shell (liner). A converging detonation wave is initiated in a circular explosive charge surrounding the liner so that it arrives at the external boundary of the liner at the instant of time when the initial magnetic field in the liner achieves a maximum. Under the action of pressure of the detonation products, the liner collapses to the center, compressing the initial magnetic flux. If the compression is rapid enough,the magnetic flux inthe cavity is preserved, and themagnetic fieldstrengthonthelineraxisincreasesinversely proportionally to the squared radius of the liner, achieving a few megagausses. The chemical energy of the explosive is transformed into the magnetic field energy through the kinetic energy of the liner. Extensive attempts made in many countries to reproduce UHMFs by the explosive compression of a magnetic flux revealed unexplainable difficulties in obtaining magnetic fields exceeding 3 MG, which resulted in the termination of work in this field. 2. MC-1 cascade generator A group of researchers at VNIIEF headed by A I Pavlovskii proposed and realized a number of concepts supplementing and developing the magnetic cumulation idea and solved the problem of the reproducible generation of UHMFs. First, it was proposed to make the shells of the MC-1 generator from a material with a controllable electrical conduction. Such a material in the initial state is either completely nonconducting or conducts current only in one direction. At the required instant, a shock wave is passed through the material, making it conducting in all directions. For example, such a material can be produced from closely packed parallel isolated copper wires glued with an epoxy compound. Second, unique solenoids of the initial magnetic field in

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 study of magnetic flux compression efficiency with a plasma shell, formed at electric explosion of a multi‐wire cylindrical frame are presented. Liners of 70 mm diameter consisting of 48 tungsten wires of 11 μm diameter were used. The liner was put into longitudinal quasi‐stationary magnetic field with induction of 0.45 T and powered with the current having amplitude up to 1.5 MA at rise time of ∼1 μs. A magneto‐optical detector recorded magnetic fields in the center of the liner system, which exceeded initial value of the magnetic field in a factor of 10.

In the paper we discuss experiments on wire liner systems powering from helical and disk magneto-cumulative generators with a current from 2...3 MA up to 20 MA at current rise time from 0.3 mu s to 1 mu s, respectively. At currents level up to 4 MA maximum yield of soft x-ray radiation was more than 100 U at plasma pinch temperature of 55 eV. At currents up to 20 MA an expected yield of soft x-ray radiation exceeds 1 MJ.

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.