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A transmission line circuit model was conducted to compare the performances of the two-level 2.5 Ω magnetically insulated transmission lines (MITLs) system of a 5-MA linear-transformer-driver (LTD) accelerator for two kinds of typical loads, including bremsstrahlung electron beam diodes and Z-pinch loads. Both the electron current loss in the pulse front during the magnetic insulation setup process and the electron flow distribution in the magnetic insulation steady state were analyzed. When the accelerator drives an electron beam diode load with impedance of 1.20 Ω (a single level), the duration of the magnetic insulation setup is about 12 ns, the current loss is about 130 kA in a single MITL level, the maximum electron flow current is about 50 kA in the end of MITL, and its amplitude decreases gradually after the steady magnetic insulation is established. When the accelerator drives a Z-pinch load with length of 1.5 cm, radius of 1.2 cm, and mass of 0.3 mg/cm, the duration of the magnetic insulation setup is almost zero, the maximum electron flow current in the end of MITL can reach about 55 kA (a single level), and the waveform of the electron flow resembles a saddle shape, which reaches the peak at the pinch stagnation time.

In order to suppress the core-corona structure (namely, the dense wire core in atomic state surrounded by plasma with high temperature and low density), two-stage wire array experiments have been carried out on Qiangguang-1 generator (1.3 MA and ~80 ns). The results showed that the shutdown time of inverse array, which consists of a central cathode rod surrounded by wires, depended on wire number. The shutdown time was 40 ns after the start of main current, when two aluminum wires were placed in inverse array, which ensured that there was still enough time during main current for load array to implode and radiate X-rays. The vaporized wire cores expanded uniformly along the axis with a smooth boundary and the average wire diameter was 1.8–1.9 mm. The vaporized wire cores were ionized rapidly after the shutdown of inverse array. The perturbations of plasma instability were first observed at the boundary of vaporized core and developed rapidly after the start of implosion. The average wavelength of these perturbations was 600– $650~\mu \text{m}$ . The precursor plasma was barely observed on the array axis in optic images. The X-ray pulse output by vaporized wire array with mega-ampere current was first given. Considering the waveform of X-rays and main current, the pinch process of the vaporized load array tended to the quasi-shell implosion. Nevertheless, there were still some fractions of plasma being left down at the initial position to lead the second implosion for the rapid development of magneto-Rayleigh-Taylor instability in implosion, which resulted in the double peaks of X-rays. The suppression methods of the implosion instability will be further studied and explored in future.

In this paper, we describe a current generator which consists of the Marx, the current-limited resistors, and the output port and can produce a double-exponential current waveform with the 3 kA, the rise time 10 ns, the pulsewidth 100 ns following the requirement of the IEC 61000-4-25 standard, while the effective impedance of the tested systems does not exceed $2~\Omega $ . A new cavity of Marx is constructed by 12 steel rods which help assembly work more convenient; moreover, the current waveform has less disturbed signal. Because of using the cavity, the charging, trigger, and grounded circuits can be installed out of the Marx. Meanwhile, the cantilever insulated support of Marx also is used. The methods above can help make a compact current generator with a low inductance which can be beneficial to research the electromagnetic coupling laws of system circuit ports and chips.

In this study, the influence of humic acid (HA) on Ni(II) sorption mechanism at illite/water interface was investigated using batch, EXAFS, and XPS. The results showed that HA can apparently inhibit the sorption of Ni(II) on illite, especially at neutral to weak alkaline conditions under a short aging time. Under low pH conditions, ion exchange (IE) and HA-bridging complexes were the main sorption mechanisms. Under neutral to weak alkaline conditions, HA-bridging complexes and surface precipitates (such as α-Ni(OH)2) gradually became predominant for Ni(II) sorption on illite at a short term. The inhibition of HA for Ni(II) sorption was deduced that: (i) the competition of soluble HA-Ni complexes, and (ii) HA-coated illite surface restrained the formation of surface-induced precipitates. With the increasing aging time, the inhibiting effect of HA became weak with respect to the surface precipitates such as Ni-Al LDH and Ni(OH)2 forming gradually. This might be caused by the growth of the available Al3 + and the surface loading of Ni(II). Moreover, β-Ni(OH)2 was the dominant species for Ni(II) sorption on illite under strong alkaline conditions. These findings in this study are providing deep insights into the understanding and prediction of Ni(II) environmental behaviors in soils enriched with natural organic matters.

In this study, sorption mechanism of Th(IV) at iron oxyhydroxide (IOHO)/water interface was studied under ambient conditions to explore the retardation effects of IOHO on actinides in the engineering barrier system of the high-level radioactive waste geological repository. The sorption of Th(IV) on IOHO was strongly dependent on pH, and the intra-particle diffusion was the rate-controlling step. The presence of humic acid can enhance the sorption of Th(IV) on IOHO below pH ~ 3.5, while slightly inhibit Th(IV) sorption above pH 3.5 due to the competing effect of humic acid remaining in aqueous phase. The surface complexation model (SCM) confirmed that the bi-dentate complex of ( FeO) 2 Th 2 + and mono-dentate complexes of FeOThOH 2 + , FeOTh(OH) 2 + and FeOTh(OH) 3 0 are controlling the sorption process of Th(IV) on IOHO. Th(IV) sorption on IOHO is favorable to high temperature with respect to the hydrolysis effect of Th(IV). XPS analysis also confirmed the above mono- and bi-dentate surface complexes of Th(IV) on IOHO, which are very sensitive to environmental conditions. Mossbauer spectroscopy showed a decreasing geometry of each components of IOHO after Th(IV) sorption, indicating the chemisorption of Th(IV) on IOHO. Moreover, the contributions from Fe 3 O 4 (A) and Fe 3 O 4 (B) components to Th(IV) sorption were higher under high temperature and initial Th(IV) concentration in comparison with α-FeOOH and amorphous Fe 3 O 4 components. The mono-dentate FeO ThOH 2 + and FeO Th(OH) 2 + complexes formed at Fe 3 O 4 (A) and Fe 3 O 4 (B) surfaces, whereas the bi-dentate ( FeO) 2 Th 2 + complex was preferring forming at the surface of α-FeOOH and amorphous Fe 3 O 4 .

β-Zeolite was synthesized and modified with ethylenediamine (EDA).The synthesized materials were characterized and used for removal of U(VI) from aqueous solutions. The influences of pH, contact time and temperature on U(VI) adsorption onto synthesized β-zeolite and modified β-zeolite by ethylenediamine (β-zeolite-EDA) were studied by batch technique, and XPS was employed to analysed the experimental data. The dynamic process showed that the adsorption of U(VI) onto β-zeolite and β-zeolite-EDA matched the pseudo-second-order kinetics model, and the adsorption of U(VI) were significantly dependent on pH values. Through simulating the adsorption isotherms by Langmuir, Freundlich and Dubini-Radushkevich (D-R) models, it could be seen respectively that the adsorption patterns of U(VI) onto β-zeolite and β-zeolite-EDA were mainly controlled by surface complexation, and the adsorption processes were endothermic and spontaneous. XPS analysis considered the formation of different complexes at different experimental conditions. The modification of β-zeolite by ethylenediamine improved the adsorption capacity of U(VI) significantly, it shows a novel material for the removing of U(VI) from water environment for industrialized application.

Based on the “QiangGuang-I” facility, three negatively enhanced microsecond water switches are experimentally studied, and their self-breakdown reproducibilities are particularly investigated and compared. Experimental results show that the annular-cathode-plate switch has a lower jitter (about 110 ns) and its lifespan can be up to 100 shots. Moreover, it is found that the close jitter decreases with the increase of negative field-enhancement factor f (the ratio of the maximum electric-field strength to the mean one of the anode-cathode gap). Finally, the experimental phenomena mentioned previously are particularly discussed according to the results of optical (3-5 ns gated charge-coupled device) and electrical diagnostics.

Magnetically insulated transmission lines (MITLs) are key components in present high-power generators. In our experiments, the current density flows in the cathode of the MITL are so high that current loss cannot be neglected. At an input current of 0.7-1.4 MA, an experimental study on current loss is performed with austenitic and martensitic stainless steel. An empirical relation between loss current density and input current density was found. For current density around 1 MA/cm, the results show that the loss current density is nearly a power function of the input current density, and the power indices for austenitic and martensite stainless steel are about 4.3 and 3.3, respectively.

The transmission-line-circuit model of the Z accelerator, developed originally by W. A. STYGAR, P. A. CORCORAN, et al, is revised. The revised model uses different calculations for the electron loss and flow impedance in the magnetically insulated transmission line system of the Z accelerator before and after magnetic insulation is established. By including electron pressure and zero electric field at the cathode, a closed set of equations is obtained at each time step, and dynamic shunt resistance (used to represent any electron loss to the anode) and flow impedance are solved, which have been incorporated into the transmission line code for simulations of the vacuum section in the Z accelerator. Finally, the results are discussed in comparison with earlier findings to show the effectiveness and limitations of the model.