High-current Relativistic Electron Beam Research Articles

Shadow streak methods for studying the interaction of relativistic electron beams with polymer targets in the high-current generator diode

When a high-current relativistic electron beam interacts with the polymer surface, plasma forms. The results of a plasma dynamics study in vacuum diode using laser shadow photography, including the effect of atypically rapid propagation of the glow, are presented. Experiments were carried out on the high current generator «Calamary». Series of the experiments to study the plasma propagation along the diode axis and in the transverse direction in different cross sections were performed. The results were discussed and possible ways to continue research were considered.

MODIFICATION OF THE ALUMINUM ALLOY BY THE RADIATION AND MECHANICAL TREATMENT

The paper discusses the problem of increasing the performance properties of aluminum alloy D16 for possible more efficient use in the fields of transport engineering. A property modification tool is a high current relativistic electron beam. The irradiation occurs in a vacuum. The peculiarities of the layer distribution of characteristic zones resulting from irradiation are investigated. Metallographic and fractographic analysis is carried out, and microhardness values are measured.

Генерация импульсов сверхизлучения терагерцового диапазона в процессе вынужденного рассеяния лазерного излучения на попутном сильноточном релятивистском электронном пучке

The possibility of generation of terahertz superradiance (SR) pulses in the case of incidental scattering of a laser pulse by a high-current relativistic electron beam with frequency conversion down is analyzed. Scattered radiation propagates in the opposite direction (with respect to the translational velocity of the particles). It is shown that when using pulses with an energy of 3 kJ at a wavelength of 1 μm as a pump during optimization of the laser pulse duration and the length of the interaction region, it is possible to generate pulses of scattered counter (relative to the translational particle velocity) radiation with a power of the order of 580 kW and a duration of 30 ps at a wavelength of 100 μm.

APPLICATION OF RADIATION PROCESSES FOR TESTING OF GAS TURBINE BLADES

Structural integrity of the gas turbine blades is of great concern. A set of methods and instruments is proposed to study the problems of the test loading of the industrial turbine blades. The approach aims to model the possible hightemperature, shock and irradiation impacts. The test loading is performed using the high-current relativistic electron beam. The developed methodology can be used for test and identification trails of the turbine blades. The experimental bench is designed to assist the thermographic measurements of the temperature dynamics in the blades. It also comprises the corresponding algorithms and software to perform the necessary calculations with.

Experimental relativistic plasma microwave electronics

Experimental studies in relativistic microwave electronics of plasma at the Prokhorov General Physics Institute are reviewed. Radiation of electromagnetic waves by a high-current relativistic electron beam injected into plasma is explored. Experimental data are compared with the results of an analytic theory and numerical simulations. Fast electronic frequency tuning of microwave radiation has been realized in an experimental setup, which is difficult to implement in vacuum relativistic microwave electronics. This is the main accomplishment of the research from the perspective of possible uses in various applications.

On Reproducibility of Collective Acceleration of Protons in a Plasma-Anode Diode System

The article deals with the investigation of the conditions of reproducibility of the results of collective acceleration of protons in a high-current relativistic electron beam of nanosecond duration passing through a plasma bunch. A quantitative criterion of reproducibility in the system of an anode with a dielectric insert and a cylindrical cathode was the neutron yield in a nuclear reaction with the threshold about 2 MeV, which was measured by a silver-activated detector after each operation of the accelerator. Generation of an azimuthally-homogeneous electron beam and plasma in the area of the dielectric insert on the anode and the use of lenses in the region of electron beam drift resulted in the stabilization of the accelerating process. After optimization, the neutron yield scatter in a series of 30 pulses was at the level ±5% of the average value, which corresponded to the accelerated proton energy scatter ±3%. The conditions of best reproducibility coincided with those where the main group of protons reached their maximum values.

RS-20MR High-Current Relativistic Electron Beam Generator Based on a Plasma Opening Switch and Its Applications

A modified scheme of the RS-20MR generator is presented that can be used not only as a source of high-power pulsed hard X-ray emission (the dose power per 1-L volume in atmospheric air exceeds 1010 rad/s) but also as a tool to study various processes occurring under the interaction of high-current electron beams with materials: excitation and propagation of shock waves, destruction of solids, etc. Due to specific properties of the sharpening system, the diode voltage pulse has a relatively steep front, which ensures the dominance electrons with energies of about 1 MeV in the beam. For electron beams with currents of I = 20–100 kA and particle energies of E ≥ 0.5 MeV, isochoric energy release can be achieved in the volume of the irradiated sample. This can lead to substantial changes in the formation mechanism of a shock wave and the character of damage it causes. The results of the first experiments of this kind are reported.

High power THz-range Wave generation based on Transformation of Plasma Waves Pumped by High-current Relativistic Electron Beam

High power THz-range Wave generation based on Transformation of Plasma Waves Pumped by High-current Relativistic Electron Beam

High-power broadband plasma maser with magnetic self-insulation

Presented in this paper are the results of a particle-in-cell modelling of a novel high-power microwave (HPM) source which combines the properties of two devices. The first prototype is a magnetically insulated transmission line oscillator (MILO), an HPM self-oscillator which does not need an external magnetic field and irradiates a narrow spectrum depending on its iris-loaded slow-wave structure. The second prototype is a plasma maser, a Cherenkov HPM amplifier driven by a high-current relativistic electron beam propagating in a strong external magnetic field in plasma which acts as a slow-wave structure. The radiation frequency of plasma masers mainly depends on an easily variable plasma concentration; hence, their spectrum may overlap a few octaves. The plasma-based HPM device described in this paper operates without an external magnetic field: it looks like an MILO in which the iris-loaded slow-wave structure is substituted by a hollow plasma tube. The small pulse duration of ∼1.5 ns prevents a feedback rise in the 20-cm long generation section so that the device operates as a noise amplifier. Unlike conventional ultra wideband generators, the spectrum depends not only on the pulse duration but mainly on plasma, so the operation frequency of the device ranges within 12 GHz. For irradiated frequencies above 2 GHz, the total pulse energy efficiency of 7% is demonstrated at the HPM power level ∼1 GW.

Generation of high-power broadband terahertz radiation during stimulated backscattering of the pump wave by an intense relativistic electron beam

The possibility of generation of high-power (multi-megawatt) broadband terahertz radiation during stimulated backscattering of an intense millimeter-wavelength pump wave by a high-current relativistic electron beam (REB) is shown. With allowance for a significant parameter spread that is typical for intense REBs, the kinetic interaction regime is expedient. This regime leads to the broadening of the scattered-radiation spectrum, but simultaneously increases the efficiency of the beam energy conversion into short-wavelength radiation.

Study of the anode plasma dynamics under the action of a high-power electron beam on epoxy resin

Results are presented from experimental studies of plasma dynamics in a diode gap under the action of a high-current relativistic electron beam on epoxy resin at energy densities in the range of 170–860 J/cm2. The plasma expansion was studied by means of an optical streak camera. Three-dimensional numerical simulations in the one-temperature hydrodynamic approximation were also performed. The experimental data are compared with the results of numerical simulations.

Relativistic Ka-band backward-wave oscillators with stable phase

Time-domain analysis of Ka-band rf signals was applied to compare the phase stability of excitation of powerful quasi-stationary and superradiance backward-wave oscillators (BWO) driven by relativistic high-current electron beam (∼500 keV, ∼4 kA). It was revealed that if the rise rate of the voltage applied to explosive electron emission cathode approaches to 1 MV/ns, then the radiation phase is linked to the voltage front region with a maximum time derivative. Besides, at all other conditions being equal, superradiance BWO demonstrates less rf phase standard deviation from pulse to pulse, as compared to a quasi-stationary one—below one picosecond on a time scale.

Comparative study of shock-wave hardening and substructure evolution of 304L and Hadfield steels irradiated with a nanosecond relativistic high-current electron beam

We present the results of a comparative study of the shock-wave hardening regularities and mechanisms revealed for bulk (thickness h = 6 and 9.3 mm) targets made of austenitic 304L stainless steel and Hadfield steel. A high-current relativistic electron beam (45 ns, 1.35 MeV, 34 GW/cm2) produced by the SINUS-7 accelerator was used for generation of a shock wave. It is revealed by 2D-computer simulation for type 304 steel that the direct ablation of the target material leads to generation of shock wave with duration of ∼0.1 μs and amplitude of ∼20 GPa, and the strain rate during its direct propagation and reflection from the free rear surface decreases from ∼2 down to ∼0.4 μs−1. It is found experimentally that in the absence of a rear spall (h = 9.3 mm) the shock-wave loading of both steels leads to formation of three hardened layers: a front layer with a maximum microhardness at a depth of 0.5–1 mm from the bottom of ablation hole, which is in a reasonable agreement with the predictions of the heat-transfer calculations, as well as intermediate and rear-side layers. In case of 304L stainless steel, the depth distributions of microhardness and fraction of twinned grains are consistent with each other, while in the Hadfield steel, the correlation is within the front and intermediate hardened layers only. It is shown by microstructural characterization and analysis of hardening mechanisms that in the case of 304L stainless steel, both front and rear-side hardening are significantly associated with the formation of new intra-phase boundaries by deformation twinning. In the Hadfield steel, unlike the 304L stainless steel, the unusual rear-side hardening is mainly due to increasing the dislocation density under submicrosecond single cycle of compression followed by tension with peak stress of ∼3 GPa.

Особенности модифицирующей обработки низкоуглеродистых сталей сильноточными релятивистскими пучками электронов

Особенности модифицирующей обработки низкоуглеродистых сталей сильноточными релятивистскими пучками электронов

Simulation of the Action of a Shock Wave on Titanium Alloy

The laws and mechanism of fracture of coarse-grain and ultrafine-grain titanium under shock-wave loading has been investigated. For the shock wave generator a "SINUS-7" accelerator emitting a nanosecond relativistic highcurrent electron beam was used. To test the high-velocity impact at velocities of the order of 2500 m/s, a ballistic installation of caliber 23 mm was used. The mathematical simulation of the high-velocity interaction was carried out with account for the fracture, the phase transitions, and the dependence of the strength characteristics of materials on the internal energy within the framework of continuum mechanics. For both granular structures the general laws and features of the fracture have been established.

Highly efficient X-band relativistic twistron

AbstractThe paper proposes a new scheme of high-power microwave oscillator of twistron type using a moderately relativistic high-current electron beam. In numerical experiment using axisymmetric version of the completely electromagnetic PiC code KARAT, a 56% conversion efficiency of electron beam power to electromagnetic radiation was demonstrated. With 340 kV accelerating voltage, 3.3 kA electron beam current, and 2.2 T guiding magnetic field strength, the simulated microwave power was 630 MW at 9.7 GHz. The “electronic efficiency” of the source reaches 66%.

Beam-plasma instability in charged plasma in the absence of ions

We report on the possibility of the beam-plasma instability development in the system with electron beam interacting with the single-component hot electron plasma without ions. As considered system, we analyse the interaction of the low-current relativistic electron beam (REB) with squeezed state in the high-current REB formed in the relativistic magnetically insulated two-section vircator drift space. The numerical analysis is provided by means of 3D electromagnetic simulation in CST Particle Studio. We have conducted an extensive study of characteristic regimes of REB dynamics determined by the beam-plasma instability development in the absence of ions. As a result, the dependencies of instability increment and wavelength on the REB current value have been obtained. The considered process brings the new mechanism of controlled microwave amplification and generation to the device with a virtual cathode. This mechanism is similar to the action of the beam-plasma amplifiers and oscillators.

Simulation and experimental investigation of the spall fracture of 304L stainless steel irradiated by a nanosecond relativistic high-current electron beam

The results of numerical and experimental investigations of the shock-wave induced spall fracture of bulk samples with thickness up to 10 mm made of 304L stainless steel irradiated by a nanosecond relativistic high-current electron beam with duration of \({\sim }\)45 ns, electron energy of 1.35 MeV, and peak power density of \(\hbox {34 GW/cm}^{2}\) are presented. By a mathematical model developed for numerical simulation of the shock-wave dynamics, it was found that a quasi-planar shock wave with duration of \({\sim }0.2\,\upmu \hbox {s}\), and initial amplitude of 17 GPa was formed in the irradiated samples. The effects of orientation of \(\updelta \)-ferrite interlayers in the austenitic matrix relative to the shock wave direction on the spall fracture were experimentally investigated. It was found that spallation was carried out by mixed ductile–brittle fracture. For the transversal orientation of \(\updelta \)-ferrite, the contribution of a brittle fracture mode in the spallation is higher than that for the longitudinal orientation. In both cases, the spalled layer thickness increased almost linearly with the increase of the target thickness, which was in good agreement with literature data. By the comparison of experimental data with simulation results, it was revealed that the spall strength can be estimated as 6.1 GPa at strain rate \(0.48\,\upmu \hbox {s}^{-1}\) and 3.4 GPa at strain rate 0.18 \(\upmu \hbox {s}^{-1}\), for samples with the longitudinal and transversal orientation of \(\updelta \)-ferrites, respectively. The comparison of the obtained spall strength values with literature data is considered.

A calorimetric dosimeter of high-power pulses of hard X rays with a lead absorber

A simple small calorimetric dosimeter for proximate measurements of the dose of high-power pulse bremsstrahlung γ-radiation was developed. The dose was measured by the heating of a lead absorber. The dosimeter was tested on a generator of a high-current relativistic electron beam with an exposure dose rate of up to 5 × 109 R/s with a total dose per pulse of up to 800 R. The maximum possible measured dose is evaluated as 3 × 105 R at a sensitivity threshold of ∼20 R under our experimental conditions.

Photo-transmutation of long-lived nuclear waste 135Cs by intense Compton [formula omitted]-ray source

MeV-range Compton γ-ray beam via Compton scattering of a laser pulse against a high-current relativistic electron beam can be used to induce photo-transmutation reactions. In this work, we investigate through Monte Carlo simulations the possibility of transmutation of radioactive nuclear waste, by high-intensity Compton γ-ray source, for the long-lived 135Cs with a half-life of 2.3×106years into short-lived 134Cs with a half-life of 2.07years, or into stable nuclide 133Cs. Our simulation results show that the transmutation reaction yield is in the order of 6×109 per hour for a given γ-flux of 2×108phs/s that can be obtained from the Shanghai Laser Electron Gamma-ray Source which is under construction. The transmutation capability of worldwide Compton γ-ray facilities is also evaluated, showing that the photo-transmutation induced by brilliant Compton γ-ray source, such as ELI-NP could be an efficient approach to transmute long-lived radioactive nuclear waste.