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In recent years, silicon dioxide nanoparticles have been widely used in medicine and the pharmaceutical industry, however, their effect on the brain has hardly been studied. We assessed the effects of long-term consumption of 5-nm amorphous silicon dioxide nanoparticles (SiO2-NPs) by Syrian hamsters infected with the trematodes Opisthorchis felineus on the hippocampus and frontal cortex. Spectroscopic determination of brain neurometabolites, performed using a horizontal Magnetic Resonance Imaging system at 11.7 Tesla magnetic field, has shown that the ratio of the excitatory neurotransmitters (glutamate + glutamine + aspartate) to the inhibitory ones (GABA + glycine) was higher in the animals infected with O. felineus. However, pre-consumption of the SiO2-NPs solution prevented this imbalance. In addition, the protective effect of SiO2-NPs on the level of myo-inositol and glycine was found. It is concluded that the use of SiO2-NPs can neutralize the negative effects of infectious factors on the brain.

A diagnostic has been developed to study the focusing dynamics of a high-power electron beam on a target. The diagnostic uses a pinhole camera to observe bremsstrahlung from the converter target. A data acquisition system yields images of the beam focal spot with a frame duration of 20 ns and an almost unlimited recording duration. The focal spot dynamics of a linear induction accelerator with an energy of 1.5 MeV, a current of 1.2 kA and a pulse duration of 350 ns were studied. The focal spot was found to be disrupted within the first 100 ns of the pulse. Defocusing has a complex 3-D character. The feasibility of additional cleaning of the target using an accelerator pre-pulse was shown. Stable beam focusing for up to 200 ns was demonstrated.

The issue of high-current electron-beam transport in the LIA-5 accelerator is discussed. The results of numerical simulation of beam transport in the 15-m-long LIA-5 accelerator channel are presented. The ASTRA macroparticle (PIC) code and two codes developed at the Budker Institute of Nuclear Physics (a code based on the solution of the Kapchinsky–Vladimirsky system of equations (K–V envelope code) and the UltraSAM code implementing the method of boundary integral equations) are used in this simulation. The experimental data agree closely with the simulation results. The electron-beam envelope is reconstructed based on the experimental luminophore data using the K–V envelope code with a genetic algorithm.

In recent years, silicon dioxide nanoparticles have been widely used in medicine and the pharmaceutical industry, however, their effect on the brain has hardly been studied. We assessed the effects of long-term consumption of 5-nm amorphous silicon dioxide nanoparticles (SiO

The work addresses the use of electron beam produced by the linear induction accelerator to generate terahertz radiation pulses of 100 MW power level based on a free electron laser scheme. The beam parameters required for efficient generation are given. The features of transverse beam dynamics when transporting the beam through the linac are investigated. Emphasis is put on the electron injector which geometry and operation parameters mainly determine the beam characteristics at the linac exit. Most of the possible factors contributing to the beam emittance gain in the accelerator are considered. The obtained analytical estimates are compared to the numerical simulation results. The experimental results on compressing and transporting the beam having the electron energy of 5 MeV and the current of 1 kA in the transport system of free electron laser are presented.

The problem of producing high-current electron beams with relatively small lateral sizes and small velocity spread is more than a hundred years old. The continuous improvement of near-ultraviolet electromagnetic radiation sources (lasers with harmonics generators) allows significantly improving the parameters of existing electron guns. This paper discusses some problems in the development of electron guns with photocathodes and considers possible ways of using laser photocathodes in the electron guns designed at the Budker INP SB RAS.

The LIA-2 linear induction accelerator has been designed in the Budker Institute of Nuclear Physics as an electron-beam injector for a promising 20-MeV induction accelerator intended for tomography. Owing to the results of the first tests, it was decided to use the injector as an independent X-ray installation [1]. In 2014, the high-voltage power supply system of the LIA-2 was upgraded and tuned. The accelerator operates stably in the one-pulse mode at energies of up to 1.7 MeV; in the double-pulse mode it operates at energies of up to 1.5 MeV. The inhomogeneity in energy in each pulse does not exceed ±0.5%.

The LIA-2 linear induction accelerator was developed at the Budker Institute of Nuclear Physics as an electron beam injector for a building induction accelerator at energy of 20 MeV, on the basis of which a complex for flash radiography will be developed. The LIA-2, which was started up in 2010, is currently used as an independent X-ray unit for raying objects with an optic thickness up to 70 mm in the lead equivalent. The effective diameter of the X-ray source is 0.6–0.7 mm.

The LIU-2 induction accelerator is described. It is used as an injector for the developed large linear induction accelerator with a maximum electron beam energy of 20 MeV, which is intended for smallangle pulse X-ray tomography. Owing to the good quality and high current of the electron beam (2 kA), the injector is capable of operating as an independent X-ray source with an electron energy of 2 MeV, the beam diameter at the target of 1 MeV is ∼20% of the total energy yield. The spread of the radiation intensity in the solid angle of 10° is ±5%, and the absorbed dose at a distance of 1 m from the target is 32 × 10−3 Gy, which allows this source to be used with attenuation of 103–104 for exposure of available X-ray films. This type of system is characterized by a high transmission capability with a 0.5-mm maximum spatial resolution of X-ray images and can be used in the X-ray imaging technique when carrying out gas-dynamic testing of products with an optical thickness as great as 90 mm of lead equivalent.

InAs/InAs0.88Sb0.12/InAs0.50Sb0.20P0.30 heterostructure photodiodes operating at room temperature in the spectral range 1–4.8 μm are developed. It is shown that the formation of a curvilinear reflecting surface constituted by a number of hemispheres on the rearside of the photodiode chip leads to an increase in the quantum sensitivity of the photodiodes by a factor of 1.5–1.7 at wavelengths in the range 2.2–4.8 μm. At an exposed photodiode area of 0.9 mm2 and a p-n junction area of 0.15 mm2, a zero-bias differential resistance of 30 Ω and a quantum sensitivity of 0.24 electron/photon at a wavelength of 3 μm are obtained. The operation of a photodiode with re-reflection of the photon flux in the crystal due to reflection from the curvilinear surface of the rearside of the photodiode chip is theoretically analyzed. The possibility of effective conversion of the re-reflected flux of photons into a photocurrent, with a simultaneous decrease in the p-n junction area, is demonstrated. An increase in the quantum sensitivity in the short-wavelength spectral range 1–2.2 μm by 35% relative to the calculated data is observed, which is probably due to impact ionization in the narrow-gap active region.

It is shown, using the example of InAs/InAsSb/InAsSbP heterostructures, that the formation of a curvilinear reflecting surface consisting of hemispherical etch pits on the rear side of a photodiode chip leads to an increase in the quantum efficiency of photodiodes by a factor of 1.5–1.7 in the entire mid-IR wave-length interval studied (λ = 3–5 μm). For the obtained photodiodes with a cutoff wavelength of 4.8 μm, a photosensitive area of 0.1 mm2, and a chip area of 0.9 mm2, a monochromatic responsivity at λ = 4.0 μm reached 0.6 A/W, while a dark current at a reverse bias voltage of 0.2 V was within 4–6 A/cm2.

A pulse power system of the induction electron accelerator intended for parameters of 2 MeV, 2 kA, and operating in the double-pulse mode is presented. The schematic diagram and main elements of the pulse system are described, and the main technical solutions intended to produce a set of pulses with 21-kV peak voltages, peak currents of up to 8 kA, and 200-ns durations across a resistive-inductive load are indicated. The experimental data, which were obtained when separate units and the whole power system operated on the rated duty, are given.

Performance of flash radiography units implies a high spatial resolution. Thus, focused electron beams are utilized to produce bremsstrahlung x-ray at the solid target. Strong heating of the target up to 1-10 eV temperature and formation of dense plasma can lead to beam disruption. In case of multi-pulse operation mode of radiography unit the plasma produced by the first pulse can strongly affect subsequent pulses. In present work we utilize the model of Zeldovich and Raizer to estimate the electron density in the target plasma. The typical parameters of radiography units based on linear induction accelerators is considered. It is shown that electron density in plasma expanding after first pulse is high enough to affect subsequent electron beams.

A 2-MeV, 2-kA Linear Induction Accelerator LIA-2 was built and is in routine operation [1, 2]. Accelerator's high voltage system consists of 48 pulsed modulators, each of them supplies a couple of accelerating gaps with two pulses of 200 ns duration at peak voltage of 21 kV and variable delay between pulses from 2 to 100 μs. Pulse forming networks with combined dielectric and TPI-type pseudospark switches are used in the modulators. Pulsed system design is described and accelerator's four-year operation results are presented.

Photodiodes with a photosensitive area diameter of 0.3 mm operating at room temperature in a middle-IR (2.5–4.9 μm) wavelength range have been created based on InAs/InAs0.94Sb0.06/InAsSbP/InAs0.88Sb0.12/InAsSbP/InAs heterostructures grown by liquid phase epitaxy. Distinguishing features of the proposed photodiodes are a high monochromatic responsivity, which reaches a maximum of 0.6–0.8 A/W at λmax = 4.0–4.6 μm, and a low dark current density of (1.3–7.5) × 10−2 A/cm2 at a reverse bias of 0.2 V. The differential resistance at zero bias reaches up to 700–800 Ω. The detection ability of photodiodes in the spectral interval of maximum sensitivity reaches (5–8) × 108 cm Hz1/2 W−1.

Directivity patterns of disk-shaped whispering gallery mode (WGM) semiconductor lasers based on quantum-confined AlGaAsSb/InGaAsSb nanoheterostructures have been studied. The cavities of disk lasers were manufactured by wet chemical etching and had the shape of a truncated cone with a height of 15 μm. The top (about 5-μm-high) part of the cavity had a cylindrical shape. A flat ring with a width equal to the thickness of the active region was protruding ∼1 μm out of the side face of the cavity. The directivity diagram of the disc WGM laser exhibits a ring-shaped interference pattern with several maxima separated by an angle of ∼6°. The interference pattern observed in both spontaneous and laser generation regimes can be explained by the interference of rays emitted directly from the ring and those reflected from the etched surface of the crystal.