Institute Of Applied Physics Research Articles

Development of Photoinjector Accelerator Complex at the Institute of Applied Physics of the Russian Academy of Sciences: Research Status and Prospects

Development of Photoinjector Accelerator Complex at the Institute of Applied Physics of the Russian Academy of Sciences: Research Status and Prospects

Near-Field Resonance Microwave Sounding to Study Dielectric Properties of Different Skin Areas (Experimental Study).

The aim of the study was to assess the near-field resonance microwave sounding efficiency to study the dielectric properties of investing tissues in different body areas in healthy rats.Materials and Methods.Skin dielectric properties (permittivity and conductivity) were studied in four body parts (medial and lumbar regions of the back, forehead, abdomen) of adult Wistar rats (n=30) using near-field resonance microwave sounding. For measurements, we used a special hardware and software system designed in the Federal Research Center Institute of Applied Physics of the Russian Academy of Sciences.Results.Dielectric properties of skin and underlying tissues significantly vary depending on a body area. The medial dorsal region was recorded to have the highest permittivity and conductivity level, while the minimum was found in the abdominal region. Frontal and caudal areas showed intermediate indices. In deepened sounding, dielectric permittivity consistently grows regardless of antenna localization (3 and 5 mm), while the conductivity recedes.Conclusion.Near-field resonance microwave sounding enabled to reveal dielectric properties specific for each body area (both by permittivity and conductivity indices and by deep structure of their distribution). The findings should be taken into consideration in topical diagnosis of investing tissues, particularly, when assessing the wound underlying structures, the localization of wound surface boundaries, and the condition of the areas around the wound.

Effects of current on wind waves in strong winds

Abstract. It is important to investigate the effects of current on wind waves, called the Doppler shift, at both normal and extremely high wind speeds. Three different types of wind-wave tanks along with a fan and pump are used to demonstrate wind waves and currents in laboratories at Kyoto University, Japan, Kindai University, Japan, and the Institute of Applied Physics, Russian Academy of Sciences, Russia. Profiles of the wind and current velocities and the water-level fluctuation are measured. The wave frequency, wavelength, and phase velocity of the significant waves are calculated, and the water velocities at the water surface and in the bulk of the water are also estimated by the current distribution. The study investigated 27 cases with measurements of winds, waves, and currents at wind speeds ranging from 7 to 67 m s−1. At normal wind speeds under 30 m s−1, wave frequency, wavelength, and phase velocity depend on wind speed and fetch. The effect of the Doppler shift is confirmed at normal wind speeds; i.e., the significant waves are accelerated by the surface current. The phase velocity can be represented as the sum of the surface current and artificial phase velocity, which is estimated by the dispersion relation of the deepwater waves. At extremely high wind speeds over 30 m s−1, a similar Doppler shift is observed as under the conditions of normal wind speeds. This suggests that the Doppler shift is an adequate model for representing the acceleration of wind waves by current, not only for wind waves at normal wind speeds but also for those with intensive breaking at extremely high wind speeds. A weakly nonlinear model of surface waves at a shear flow is developed. It is shown that it describes dispersion properties well not only for small-amplitude waves but also strongly nonlinear and even breaking waves, which are typical for extreme wind conditions (over 30 m s−1).

Higher Operating Temperature IR Detectors of the MOCVD Grown HgCdTe Heterostructures

This paper summarizes progress in metal organic chemical vapour deposition (MOCVD) technology achieved in recent years at the Institute of Applied Physics, Military University of Technology and VIGO System S.A. MOCVD with a wide range of composition and donor/acceptor doping and without post-growth annealing is a very convenient tool for the deposition of HgCdTe epilayers used for uncooled infrared detectors. Particular attention is focused on: surface morphology improvement, doping issues, diffusion processes during growth study, substrate issues, crystallographic orientation selection. In this respect, MOCVD technology improvement influencing IR detector parameters is shown. CdTe buffer layer deposition allows HgCdTe heterostructure growth on GaAs substrates. Theoretical modelling using APSYS platform supports designing and better understanding of the carrier transport mechanism in detector’s structures. Secondary ion mass spectrometry profiles allows to compare projected and obtained structures and revealed diffusion processes of the elements. A wide range of different types of infrared detectors operating at high operating temperature conditions has been constructed: photoresistors, non-equilibrium photodiodes, dual-band photodiodes, barrier and multiple detectors. The methodical research efforts contributed to the time constant reduction are important in many detector applications. Future challenges and prospects are also discussed.

Gyrotron-Based Technological Systems for Material Processing—Current Status and Prospects

Among various applications of the gyrotrons to the fundamental physical research and to the high-power terahertz science and technologies, the material treatment based on the irradiation by millimeter and sub-millimeter waves is both one of the oldest and most advanced (industrial grade) technologies. In this paper, we present the recent advancements and the current status of both the development of gyrotron-based technological systems and their utilization for processing of diverse advanced materials. The current status of the work in this broad field worldwide is illustrated mainly by representative results obtained during the longstanding (more than 20 years since 1999) and fruitful collaboration between the Institute of Applied Physics of the Russian Academy of Sciences (IAP-RAS) and Research Center for Development of Far-Infrared Region, University of Fukui (FIR-UF).

Ultrahigh “Relative Energy Density” and Mass Loading of Carbon Cloth Anodes for K-Ion Batteries

Mass loading and potential plateau are the two most important issues of potassium (K)-ion batteries (KIBs), but they have long been ignored in previous studies. Herein, we report a simple and scala...

Neutronics conceptual research on a hybrid blanket of china fusion engineering test reactor

• A hybrid CFETR blanket using natural uranium U-10Zr alloy and water is proposed. • Multi-layer alternate arrangement of fission zone and tritium breeding zone is used. • 3D detailed neutronics model is built for JMCT by CMGC. • MCNP results are crosschecked by JMCT. • TBR and M are 1.26 and 3.18 respectively. The engineering concept research of China Fusion Engineering Test Reactor (CFETR) is underway. In order to achieve tritium self-sufficiency and lower tritium startup inventory, a fusion fission hybrid blanket scheme is proposed in this paper as a backup for the traditional pure fusion blanket concepts. In the hybrid blanket design, natural uranium is used as fuel, light water as coolant and Li 4 SiO 4 as tritium breeder. MCORGS, a burnup code coupled by MCNP and ORIGENS, is used in burnup calculation. JMCT, a Joint Monte Carlo Transportation code developed by Institute of Applied Physics and Computational Mathematics, is used to crosscheck the MCNP results. One dimensional design and optimization is firstly made to propose a multi-layer alternate arrangement of fission zone and tritium breeding zone so as to maximum Tritium Breeding Ratio (TBR) and a moderate energy Multiplication (M). A 3D neutronics model of CFETR is converted from MCNP benchmark files to a GDML file which is used in JMCT. At the beginning of the core, TBR 3D is 1.26 which is bigger than the max achievable TBR for pure fusion blanket (around 1.15), M is 3.18 which means the tritium startup inventory will be 3 times lower than the pure fusion blanket in case of a fixed blanket thermal power. After 12 years burnup with 200 MW fusion power, TBR and M will be 1.28 and 4.05 respectively. The hybrid system is in an ultra deep subcritical state, the effective multiplication constant varies from 0.161 to 0.227. If the natural uranium in fission zone is replaced by spent fuel or LEU, more higher TBR and M will be obtained.

Simulation of High-Altitude Discharges in a Large Plasma Facility

The most important factor determining the dynamics and structure of high-altitude discharges is the significant difference in atmospheric pressure along their length. The Sprite device was designed at the Institute of Applied Physics. It makes it possible to produce an extended concentration gradient of a neutral gas and ignite a large-scale electric discharge in it. This work presents the results of laboratory experiments simulating some properties of high-altitude discharges, primarily sprites and gigantic jets. A high-voltage pulse discharge, which is similar to sprites and gigantic jets in structure, is studied using a wide arsenal of laboratory diagnostics, including macroscopic electrophysical measurements, inductive probes for measurement of the spatial current profile, plasma microwave interferometry, and photography with nanosecond exposures. The similarity of laboratory and natural discharges is shown, and the physical problems and possible means of their solution with limited laboratory simulation are indicated.

(Invited) High Temperature Steam/CO2 Co-electrolysis Using Solid Oxide Electrolyser Stack at Shanghai Institute of Applied Physics

The high temperature steam/CO2 co-electrolysis using solid oxide electrolyser cell technology is considered to be an important alternative for syngas production with carbon-free process. Previously, the co-electrolysis of steam and CO2 in single cell have been published in Faraday Discussions by our team, and electrolysis parameters have been investigated and optimized systematically. In this paper, we carried out the steam/CO2 coelectrolysis experiment using a 30-cell SOC stack composed of NiO-YSZ/YSZ/GDC/LSCF-GDC with the single cell effective area of 63cm2 (developed by Ningbo SOFCMAN Energy Technology Co., Ltd). The electrochemical performance of stack was investigated through OCV, I-V and long-term stability tests. From OCV and I-V curves, we can see the electrochemical performance of steam/CO2 co-electrolysis is slightly worse than that of steam electrolysis. And stability test was carried out in galvanostatic electrolysis mode (750 oC, 0.25 A/cm2, H2/H2O/CO2= 20/53.33/26.67(molar ratio); H2: 1.645NL/min) for 100hrs, the product of hydrogen electrode was analysis though rotameter and Agilent gas chromatograph 7820 , and the steam and CO2 utilization can be calculated to be 55.38% and 46.33%, respectively. Figure 1

Effect of cold helium plasma on the catalytic activity of certain erythrocyte dehydrogenases of rat blood

The work is aimed at clarifying the effect of cold helium plasma on the catalytic properties of lactate- and aldehyde dehydrogenase in rat blood erythrocytes. The effect was studied in 20 white Wistar rats. Upon completion of the full course of exposures (1 exposure per day for 5 days), blood samples were taken from all animals with subsequent erythrocyte isolation performed by standard differential centrifugation for assessing the activity of lactate dehydrogenase (LDH) and aldehyde dehydrogenase (AlDH). When assessing LDH activity, both direct and reverse reactions were considered. Gas flow microwave ionisation was applied to the synthesis of cold plasma using a special device developed at the Institute of Applied Physics, Russian Academy of Sciences. The plasma treatment was established to provide stimulation of LDH activity in both direct and reverse reactions. In the direct reaction, erythrocytic LDH activity in rats with plasma-treated skin almost doubled (94 %) against 48 % of activity growth in the reverse reaction. Rat blood erythrocyte AlDH tends to moderate inactivation, with catalytic properties observed to decrease by 13 %. Thus, treating the skin of healthy rats with cold helium plasma was demonstrated to stimulate the energy metabolism of blood cells, with moderate activity inhibition for AlDH presenting one of the detoxification enzymes. The nature of the observed shifts indicates their adaptability. In general, according to the obtained data, the modulation of free radical processes was confirmed to play a key role in the molecular-cellular mechanisms of the cold helium plasma action on the biological system.

The special nuclear data library CENDL-TMSR for thorium-uranium cycle

Thorium molten salt reactor nuclear energy system (TMSR), which is the fourth generation advanced nuclear energy system, needs more advanced and reliable physical design. The reliability and accuracy of nuclear data has very important impact on the accuracy of nuclear design. According to the requirement of Shanghai Institute of Applied Physics, Chinese Academy of Sciences, China Nuclear Data Center has developed a special nuclear data library CENDL-TMSR for thorium-uranium cycle, which includes evaluated nuclear data library and application libraries for criticality calculation and shielding design of thorium molten salt reactor. In order to verify and validate the reliability and applicability of the CENDL-TMSR, the criticality benchmarking and shielding benchmarking are carried out. The criticality testing results show that the relative errors between calculated k eff and experimental values for most benchmarks are within 0.5%, which indicates that the CENDL-TMSR can be used for physical design of thorium molten salt reactor. The shielding calculation results are consistent with the experimental ones, and the overall performances are better than other evaluated nuclear data libraries.

Features of Profiles for Currents, Momentum Flux, and a Turbulence Dissipation Rate in Wind-Wave Channel

Vertical profiles of the mean horizontal currents U(z), the vertical momentum fluxes τ(z), and the turbulence kinetic-energy dissipation rates (TKE dissipation rate) e(z) in the upper water layer (UWL) are considered and their joint analysis is carried out. For this purpose, data from laboratory measurements performed in the wind-wave channel of the Institute of Applied Physics, Russian Academy of Sciences (RAS) [1, 2], are used. They correspond to conditions of strong wind and breaking wind waves. The profiles of the currents and momentum fluxes are estimated for x and z components of the velocity at five horizons in the UWL at four various wind values. The empirical estimates of e(z) obtained from the same data in the previous work [3] are used in the joint analysis. It is established that (a) velocity of currents U(z) increases noticeably when compared to the values of U(z) in the absence of waves, (b) the momentum flux in the water τw(z) decreases noticeably when compared to that in the air τa(z), and (c) τw(z) significantly attenuates with depth according to ratio τw(z) ~ 1/z2. The mentioned anomalies of profiles U(z) and τ(z) in the UWL are analyzed together with the previously determined pattern of TKE dissipation-rate falloff with depth according to ratio e(z) ~ 1/z2 in order to search for an interpretation of the results.

Study of the dynamic hardness of structural metal materials

The mechanical properties of structural metallic materials are the most important indicators of their quality. Different methods (i.e., the methods of Shore, Brinell, Rockwell, Leeb, Vickers, method of instrumental indentation, and others) are currently used for determination of the hardness — one of the most important mechanical characteristics of structural metal materials. Among them is the method of dynamic indentation first developed at the Institute of Applied Physics of the National Academy of Sciences of Belarus. With the goal of further developing of the method of dynamic indentation, we propose the procedures aimed at increasing the accuracy of assessing the hardness of structural metallic materials: parameters of the contact interaction of the indenter with the sample material (Brinell hardness values) were measured using a dynamic indentation (DI) device; the values of surface and volumetric dynamic hardness were calculated taking into account the characteristics obtained using a DI device; a comparative analysis of hardness estimates obtained by different approaches was carried out. As a result of the comparative analysis of the methods, as well as their experimental testing, it was shown that an increase in the accuracy of hardness assessment can be achieved by using the «energy» approach based on assessing the ratio of the total work to the volume of the recovered indentation upon dynamic indentation of structural metal materials. The use of the «energy» approach provided obtaining the sample standard deviation of the volumetric dynamic hardness values, which, in turn, was significantly lower than the sample standard deviation of the surface dynamic hardness values and data of the dynamic indentation device, which directly affects an increase in the accuracy of hardness estimation during dynamic indentation of structural metal materials. Proceeding from the «energy» approach, a new algorithm for processing the initial signal is proposed when the dynamic hardness is determined using a dynamic indentation device.

A powerful pulsed “point-like” neutron source based on the high-current ECR ion source

The paper presents recent results of a "pointlike" neutron source development based on a D-D fusion in a D-loaded target caused by its bombardment with a sharply focused deuterium ion beam. These developments are undergoing at the Institute of Applied Physics of Russian Academy of Sciences in order to study a possibility to create an effective and compact device for fast-neutron radiography. The last experiments with a beam produced by a gasdynamic high-current ECR ion source and its focusing with a magnetic lens demonstrated that 60 mA of deuterium ions may be constricted to a transversal size of ∼1 mm at the focal plane. With a purpose to improve this result in terms of the beam current and its size, a combined electrostatic and magnetic focusing system is proposed and analyzed. It is shown that the combined system may enhance the total beam current and reduce its footprint down to 0.13 mm. All numerical analysis was performed using the IBSimu code.

Studies of a Gyrotron Traveling-Wave Tube with Helically Corrugated Waveguides at IAP Ras: Results and Prospects

The gyrotron traveling-wave tube (gyro-TWT) is a wideband version of gyrotron amplifiers, which produce pulsed or continuous-wave radiation in the millimeter-wavelength band at a power level that exceeds the powers produced by conventional TWTs with slow-wave structures and rectilinear beams by 1–2 orders of magnitude. Since 1996, researchers at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) have been developing the concept of the gyro-TWT based on the use of a waveguide with a helically corrugated surface, which changes the dispersion of one of the eigenmodes in a circular waveguide radically. In this paper, we discuss several problems that arise in implementation of such devices, which many years of experimental studies have revealed, present the parameters of gyro-TWTs developed with allowance for specific applications of their end users, and discuss lines of further perfection of such amplifiers.

An Experimental Study of the External-Signal Influence on the Oscillation Regime of a Megawatt Gyrotron

The radiation-frequency locking by an external signal is experimentally studied for a megawatt gyrotron. An external signal from a magnetron is applied to the operation space of the gyrotron at a frequency of 35 GHz via a synthesized two-mirror quasioptical converter developed at the Institute of Applied Physics of the Russian Academy of Sciences. The radiation spectra are measured for both the frequency locking regime and the frequency beats. The locking region is constructed on the plane of two parameters, namely, the external-signal power and frequency. The experimental and theoretical results are compared to show a good agreement.

Locking of the Frequency of a Multimode Gyrotron by a Quasi-Monochromatic External Signal

We consider the influence of an external quasi-monochromatic signal on a multimode gyrotron in the case where the signal frequency is close to the frequency of the operating mode of the gyrotron. The influence of the mode competition on the generation regime at a harmonic frequency modulation is studied. The calculations were performed for a high-power 170 GHz gyrotron developed at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS). Depending on the parameters of the gyrotron and the external signal, various generation regimes were determined, including locking of the operating-mode frequency when the radiation frequency is close to the frequency of the external signal, beats of the frequency and amplitude of the operating mode, and excitation of spurious modes.

High-Harmonic Gyrotrons with Axis-Encircling Electron Beams at IAP RAS

The Institute of Applied Physics of the Russian Academy of Sciences has for many years been developing sub-terahertz and terahertz large-orbit gyrotrons that permit selective oscillation at higher cyclotron harmonics than is possible in the conventional gyrotrons. Currently, experimental studies are conducted at two specialized facilities. A prototype universal sub-terahertz source for magnetic resonance spectroscopy is studied using a facility that generates long-pulse and continuous electron beams with particle energies of up to 30 KeV. Continuous selective oscillation at the second and third cyclotron harmonics with frequencies of 0.267 and 0.394 THz was obtained for a radiation power of 900 and 370 W, respectively. New resonators with periodic phase correctors have been developed to increase the efficiency of third-harmonic oscillation and obtain fourth-harmonic oscillation with frequencies of up to 0.65 THz. Using a facility with an electron energy of up to 80 KeV, we study the possibilities of increasing the pulse generation power at the third harmonic at frequencies close to 1 THz to employ in experiments on obtaining a gas discharge in a focused terahertz wave beam and generating high-power extreme ultraviolet radiation.

Power losses caused by longitudinal HOMs in 3.9 GHz SHINE cryomodule

Shanghai high repetition-rate XFEL and extreme light facility (SHINE), the first hard XFEL based on a superconducting accelerated structure in China, is now under development at the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. In this paper, power losses caused by trapped longitudinal high order modes (HOM) and steady-state loss generated by untrapped HOMs in 3.9 GHz SHINE cryomodule will be investigated and calculated. Results are presented for power losses of every element in 3.9 GHz cryomodule, caused by HOM excitation in the acceleration RF system of the continues-wave (CW) linac of SHINE.

Design a precise stability controller for high power pulse modulator based on FPGA

Shanghai Soft X-ray Free Electron Laser Test Facility (SXFEL-TF) has been fulfilled the construction assignments and passed the acceptance check at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. The stability of microwave system is one of the major factors to get better beam performance. It is mainly determined by klystron and modulators power supply. The beam voltage stability of pulse modulator, which is the cathode voltage source of the microwave amplifier, is directly affecting the microwave amplitude and phase. The requirement of the microwave stability is 0.04% (rms) for amplitude and 0.05% (rms) for phase tolerance. This paper shows the design considerations of stability improvement and suitable upgrade scheme of the controller for Shanghai SXFEL pulse modulator.