Wire, hybrid, and laser-cut X-pinches as Talbot-Lau backlighters for electron density diagnostics

Talbot-Lau X-ray Deflectometry (TXD) enables refraction-based imaging for high-energy-density physics (HEDP) experiments, and thus, it has been studied and developed with the goal of diagnosing plasmas relevant to Inertial Confinement and Magnetic Liner Inertial Fusion. X-pinches, known for reliably generating fast (~1 ns), small (~1 µm) x-ray sources, were driven on the compact current driver GenASIS (~200 kA, 150 ns) as a potential backlighter source for TXD. Considering that different X-pinch configurations have characteristic advantages and drawbacks as x-ray generating loads, three distinct copper X-pinch configurations were studied: the wire X-pinch, the hybrid X-pinch, and the laser-cut X-pinch. The Cu K-shell emission from each configuration was characterized and analyzed regarding the specific backlighter requirements for an 8 keV TXD system: spatial and temporal resolution, number of sources, time of emission, spectrum, and reproducibility. Recommendations for future experimental improvements and applications are presented. The electron density of static objects was retrieved from Moiré images obtained through TXD. This allowed to calculate the mass density of static samples within 4% of the expected value for laser-cut X-pinches, which were found to be the optimal X-pinch configuration for TXD due to their high reproducibility, small source size (≤5 µm), short duration (~1 ns FWHM), and up to 10^6 W peak power near 8 keV photon energy. Plasma loads were imaged through TXD for the first-time using laser-cut X-pinch backlighting. Experimental images were compared with simulations from the X-ray Wave-Front Propagation code, demonstrating that TXD can be a powerful x-ray refraction-based diagnostic for dense Z-pinch loads. Future plans for Talbot-Lau Interferometry diagnostics in the pulsed-power environment are described.

Remarkably enhanced dielectric stability and energy storage properties in BNT—BST relaxor ceramics by A-site defect engineering for pulsed power applications

Lead-free bulk ceramics for advanced pulsed power capacitors show relatively low recoverable energy storage density (Wrec) especially at low electric field condition. To address this challenge, we propose an A-site defect engineering to optimize the electric polarization behavior by disrupting the orderly arrangement of A-site ions, in which $${\rm{B}}{{\rm{a}}_{0.105}}{\rm{N}}{{\rm{a}}_{0.325}}{\rm{S}}{{\rm{r}}_{0.245 - 1.5x}}{_{0.5x}}{\rm{B}}{{\rm{i}}_{0.325 + x}}{\rm{Ti}}{{\rm{O}}_3}$$ Ba 0.105 Na 0.325 Sr 0.245 − 1.5 x □ 0.5 x Bi 0.325 + x TiO 3 ($${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ BNS 0.245 − 1.5 x □ 0.5 x B 0.325 + x T , x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ BNS 0.245 − 1.5 x □ 0.5 x B 0.325 + x T ceramics are prepared by using pressureless solid-state sintering and achieve large Wrec (1.8 J/cm3) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm3 is super high as compared to all other Wrec in lead-free bulk ceramics under a relatively low electric field (< 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40–350 °C is also obtained in $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ BNS 0.245 − 1.5 x □ 0.5 x B 0.325 + x T (x = 0.06) ceramics. The excellent performances can be attributed to the A-site defect engineering, which can reduce remnant polarization (Pr) and improve the thermal evolution of polar nanoregions (PNRs). This work confirms that the $${\rm{BN}}{{\rm{S}}_{0.245 - 1.5x}}{_{0.5x}}{{\rm{B}}_{0.325 + x}}{\rm{T}}$$ BNS 0.245 − 1.5 x □ 0.5 x B 0.325 + x T (x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi0.5Na0.5TiO3 (BNT)-based ceramics with high Wrec and high-temperature stability.

Мобильный ускоритель на базе безжелезного импульсного бетатрона для радиографирования динамических объектов

The paper concerns the mobile accelerator based on the ironless pulsed betaron. The accelerator is aimed to radiograph dynamic objects with a large optical thickness. It has a possibility to obtain up to three γ-pulses in one cycle of the acceleration. The accelerator operation description and results of its testing powering in a single-pulse mode are provided. The estimated boundary energy of an electron beam is equal to 60 MeV at the capacitance value of 1.8 mF of the storage of the betatron electromagnet pulsed power system. The thickness of the lead test object examined with γ-rays is 140 mm at 4 m from the tantalum target. The full width of the output γ-pulse at half maximum is equal to 120 ns. The dimension of the radiation source is 3×6 mm. The application of these accelerators within the radiographic complex will allow increasing the investigation efficiency due to the optimization of the hydrodynamic experiments geometry and the cost reduction.

Pulsed power applications for agriculture and food processing

Recently, pulsed power technologies, including pulsed electric fields (PEFs) and time-modulated plasmas, are starting to be applied actively in agriculture and food processing. In the applications, compact pulsed power generators with moderate peak power and repetitive operation are developed for controlling discharge plasmas and electric field distribution. These applications are mainly based on the biological effects of a spatially distributed electric field and the chemically active species in the plasma. The PEFs are caused by applying pulse voltage between the electrodes and contribute to form pores on the cell membrane or to change conformation of protein. When the applied voltage exceeds the discharge onset criterion, plasmas are generated through the avalanche process of electron accelerated with intense electric field in a gas or liquids medium. The plasmas produce chemically active species, UV radiation, an intense electric field in the vicinity of discharge channel and shock waves, which also have different biological effects. The agricultural applications of pulsed power can be categorized as two phases: pre-harvest and post-harvest phases. The pre-harvest phase consists of seed germination, seedling growth, plant growth and growth mode change from vegetative to reproductive. Pulsed power technologies are used to promotion of seed germination, plant growth enhancement through direct stimulation or indirect effect such as inactivation of bacteria in soil and liquid hydroponic media, and promotion of mushroom fruit body formation. The post-harvest phase consists of harvesting the agricultural produce, storing the products, transporting the products to consumers and food processing such as drying, pasteurization (sterilization of bacteria), permeabilization and fermentation. The pulsed power technologies are also used to keep freshness of agricultural produce through decontaminating airborne, inactivating bacteria and decomposition of plant hormone in the storage containers. The poration of cell membrane by PEF contributes improvement of extraction of juice, nutritional agents, and antioxidant metabolites such as polyphenols from agricultural products. In this review, at first, a basis of pulsed power system for agricultural applications and bio-effect by high-electric field exposure is outlined. After that, pre-harvest and post-harvest agricultural applications are described. The utilization of pulsed power technologies to contribute efficient food processing and improve food safety and quality is also described.