40 year anniversary of the RADAN systems – compact pulsed power sources for various investigations

This article includes a brief overview of the compact RADAN-series subgigawatt pulsed voltage sources and describes their capabilities in various electrophysical researches. We present the results obtained in the experiments at nano- and subnanosecond time scales on the formation of the voltage pulses with a special shape, electron beams emission in air gaps and by the cold cathodes in vacuum, as well as generation of electromagnetic radiation. Particular attention is paid to the promising application of the RADAN systems.

A compact platform for the investigation of material dynamics in quasi-isentropic compression to ~ 19 GPa

This paper reports on the development of a magnetically driven high-velocity implosion experiment conducted on the CQ-3 facility, a compact pulsed power generator with a load current of 2.1 MA. The current generates a high Lorentz force between inner and outer liners made from 2024 aluminum. Equally positioned photonic Doppler velocimetry probes record the liner velocities. In experiment CQ3-Shot137, the inner liner imploded with a radial converging velocity of 6.57 km/s while the outer liner expanded at a much lower velocity. One-dimensional magneto-hydrodynamics simulation with proper material models provided curves of velocity versus time that agree well with the experimental measurements. Simulation then shows that the inner liner underwent a shock-less compression to approximately 19 GPa and reached an off-Hugoniot high-pressure state. According to the scaling law that the maximum loading pressure is proportional to the square of the load current amplitude, the results demonstrate that such a compact capacitor bank as CQ-3 has the potential to generate pressure as high as 100 GPa within the inner liner in such an implosion experiment. It is emphasized that the technique described in this paper can be easily replicated at low cost.

Pulsed Power Applications for Protein Conformational Change and the Permeabilization of Agricultural Products

Pulsed electric fields (PEFs), which are generated by pulsed power technologies, are being tested for their applicability in food processing through protein conformational change and the poration of cell membranes. In this article, enzyme activity change and the permeabilization of agricultural products using pulsed power technologies are reviewed as novel, nonthermal food processes. Compact pulsed power systems have been developed with repetitive operation and moderate output power for application in food processing. Firstly, the compact pulsed power systems for the enzyme activity change and permeabilization are outlined. Exposure to electric fields affects hydrogen bonds in the secondary and tertiary structures of proteins; as a result, the protein conformation is induced to be changed. The conformational change induces an activity change in enzymes such as α-amylase and peroxidase. Secondly, the conformational change in proteins and the induced protein functional change are reviewed. The permeabilization of agricultural products is caused through the poration of cell membranes by applying PEFs produced by pulsed discharges. The permeabilization of cell membranes can be used for the extraction of nutrients and health-promoting agents such as polyphenols and vitamins. The electrical poration can also be used as a pre-treatment for food drying and blanching processes. Finally, the permeabilization of cell membranes and its applications in food processing are reviewed.

Structure and dielectric properties of NBT-xBT-ST lead-free ceramics for energy storage

([Formula: see text])(Na[Formula: see text]Bi[Formula: see text])TiO3-[Formula: see text]BaTiO3-0.26SrTiO3 ([Formula: see text]) (abbreviated as NBT-[Formula: see text]BT-ST) lead-free ceramics were fabricated by a solid-state reaction method. The effect of Ba doping amount [Formula: see text] on the structure and energy storage properties of NBT-[Formula: see text]BT-ST ceramics were investigated. All the NBT-[Formula: see text]BT-ST ceramics showed single perovskite structure with a pseudocubic phase. Ba doping effectively suppressed grain growth, in favor of forming small and uniform grains. The ceramics with a composition of [Formula: see text], an optimized energy storage density ([Formula: see text][Formula: see text]J/cm3) and efficiency ([Formula: see text]%), under an applied electric field of 50[Formula: see text]kV/cm, should be a candidate for solid-state compact pulsed power capacitor materials.

Characterizations of dynamic material properties on compact pulsed power generator CQ-4

Over last two decades, the techniques of magnetically driven quasi-isentropic compression and launching high velocity flyer plates based on pulsed high current generators have being extensively used to do dynamic material experiments under extreme conditions, such as high pressure, high temperature and high strain rate. A compact pulsed power generator CQ-4 was developed to do quasi-isentropic compression experiments of materials at Institute of Fluid Physics of CAEP, which can deliver maximum peak current of about 4 MA to short-circuit loads and produce approximate 100 GPa pressure on the metallic samples. On CQ-4, several types of dynamic material experiments have being conducted for equation of states, phase transitions, constitutive relationships, micro-structure evolutions of matter under quasi-isentropic compression and shock loadings. Meanwhile the dynamic behaviors of solid plastic bonded explosives and their components have also being researched for better understanding the interaction of explosive components under stress waves and the hot spot originations and evolutions mechanism of PBX explosives under dynamic loadings. Several typical applications in dynamic material properties were shown in this paper to exhibit the capabilities of CQ-4.