Formation and Diagnostics of Intense Relativistic Helical Electron Beams for Gyrotrons

We develop a magnetron-injection gun for a 1-cm wavelength gyrotron, which allows us to increase the operating current up to 50% of the Langmuir current of the gun by reducing the time required to bring electrons to the high-potential region. To measure the velocity distributions in helical electron beams for energies of several hundreds of keV, we propose, develop, and study a new electron-velocity distribution analyzer based on the phenomenon of electron reflection from an adiabatic magnetic mirror. The results of our study demonstrate that the gun is capable of forming high-quality intense beams suitable for generating microsecond microwave radiation with power higher than 10 MW in gyrotrons.     

Possible Sources of Electron Neutrinos with a Modulated Monochromatic Component

A directed beam of electron neutrinos can be created by means of accumulating ions with β⁺-unstable nuclei in a storage ring. Such a neutrino beam may contain a significant monochromatic component, if these nuclei decay via electron capture with a sizable probability. Under specific conditions— in particular, in the case of employing hydrogen-like ions—this monochromatic component can be modulated. Requirements for β⁺-unstable nuclei of such hydrogen-like ions are discussed, and β⁺- decaying nuclides most appropriate for creating intense sources of electron neutrinos with amonochromatic component admitting modulation are indicated.     

Generation of High-Power Ultrashort Optical Pulses Using a Semiconductor Laser with Controlled Current Pumping

Technical Physics - Fiber-coupled semiconductor lasers are studied under pumping with high-power short current pulses. Appropriate parameters of the current pumping make it possible to...     

Electronic Circuits for the Generation and Transfer of High-Power Pulses in Nuclear Fusion Installations

The toroidal confinement and the ohmic heating of a thermonuclear plasma as used in tokamak experiments can be achieved by strong magnetic fields and by a heavy direct current flowing parallel to the axis of the plasma torus. This current can be induced with the aid of a transformer for which the plasma torus acts as the secondary winding. The high loop voltage required for start-up is obtained by commutation of the primary current to a resistor. This commutation can be achieved by a mechanical switch or by electronic circuits. New electronic commutation circuits are described which enable very heavy direct currents to be switched without contacts. The operation of the new circuits was checked by computer calculations. Experiments have not yet been performed.     

Recirculating Electron Accelerators with Noncircular Electron Orbits as Radiation Sources for Applications (a Review)

State-of-the-art compact recirculating electron accelerators operating at intermediate energies (tens of MeV) are reviewed. The acceleration schemes implemented in the rhodotron, ridgetron, fantron, and cylindertron machines are discussed. Major accelerator components such as the electron guns, accelerating cavities, and bending magnets are described. The parameters of currently operating recirculating accelerators are tabulated, and applications of these accelerators in different processes of irradiation are exemplified.     

Electron Acceleration and Bunch Generation by Intense Femtosecond Laser Pulse in Preplasma of a Target

We present analytical studies of electron acceleration in the low-density preplasma of a thin solid target by an intense femtosecond laser pulse. Electrons in the preplasma are trapped and accelerated by the ponderomotive force as well as the wake field. Two-dimensional particle-in-cell simulations show that when the laser pulse is stopped by the target, electrons trapped in the laser pules can be extracted and move forward inertially. The energetic electron bunch in the bubble is unaffected by the reflected pulse and passes through the target with small energy spread and emittance. There is an optimal preplasma density for the generation of the monoenergetic electron bunch if a laser pulse is given. The maximum electron energy is inverse proportion to the preplasma density.     

Electron Acceleration and Bunch Generation by Intense Femtosecond Laser Pulse in Preplasma of a Target

We present analytical studies of electron acceleration in the low-density preplasma of a thin solid target by an intense femtosecond laser pulse. Electrons in the preplasma are trapped and accelerated by the ponderomotive force as well as the wake field. Two-dimensional particle-in-cell simulations show that when the laser pulse is stopped by the target, electrons trapped in the laser pules can be extracted and move forward inertially. The energeticelectron bunch in the bubble is unaffected by the reflected pulse and passes through the target with small energy spread and emittance. There is an optimal preplasma density for the generation of the monoenergetic electron bunch if a laser pulse is given. The maximum electron energy is inverse proportion to the preplasma density.     

周期量级强激光场中电子振荡所导致的辐射的空间分布特性

采用单电子模型,通过理论分析和计算机模拟,研究了线偏振周期量级强激光脉冲作用下电子的相对论运动及其辐射的空间分布特性,研究发现对周期量级的强激光脉冲,其初始位相对电子的相对论运动及其辐射的空间分布特性影响非常显著。     

Relativistic Electron Acceleration in a Wake Field Generated by the Intense Femtosecond Laser Interaction with a Mixture Jet of Deuterium Clusters and Molecules

High energy electron acceleration in a wake field generated in the intense ultrashort （30fs） laser pulse cluster gas jet interaction is experimentally demonstrated. Relativistic electrons with energy of 60 MeV were observed. These high energy electrons split into two beams due to the relativistic self-focusing of the laser.     

Sources of High-Power Continuous-Wave Multi-Frequency Radiation for Plasma Applications Based On Gyroresonance Traveling-Wave Tubes with a Helically Corrugated Waveguide

Radiophysics and Quantum Electronics - We present the results of studying experimentally gyroresonance K-band traveling-wave tubes having kilowatt power levels in the output radiation, in which the...     

强脉冲离子束与新材料工艺

近几年强脉冲离子束胜材料表面改性和薄摹研究表明，强脉冲能量效应赋予离子束新的物理性质，非常有希望形成高效率、低成本的离子束工艺，为此对脉中功率密度为１０＾－６－－１０＾９Ｖ／ｃｍ＾２、脉冲宽度〉１μｓ的强脉冲子束辐照效应强脉冲离子源及其在材料研究中的应用前景进行了评述。     

Submicrosecond Pulsed Electron Beam Formation in Electron Sources and Accelerators with Plasma Emitters

The most popular methods for submicrosecond electron beam generation and physical processes underlying electron extraction from plasma in plasma emitters are considered. Electron sources and accelerators developed on the basis of plasma emitters allow pulsed beams with currents from tens to 10³ A and current densities of several amperes per square centimeter, pulse durations of hundreds of nanoseconds, and high repetition rates to be generated.     

Theory and Calculation of Electrostatic Electron Mirrors with Allowance for Relativistic Effects

Technical Physics - Trajectory equations of charged particles are derived using the central particle method with an accuracy of up to quantities of the third order of smallness inclusive in an...     

Electron Sources with Plasma Grid Emitters: Progress and Prospects

Russian Physics Journal - Operational principles and main characteristics of electron sources based on plasma emitters with grid/layer stabilization of the boundary of the emission plasma generated...     

Self-Modulation and Chaotic Regimes of Generation in a Relativistic Backward-Wave Oscillator with End Reflections

We study self-modulation and chaotic regimes of generation in a relativistic backward-wave oscillator in the presence of reflections of radiation from the boundaries of a slow-wave structure. The onset of self-modulation is examined in detail in the cases of weak and strong reflections. A numerical simulation of transition-to-chaos scenarios is performed over a wide range of parameters. The relation of bifurcation transitions between different regimes to the formation of spatio-temporal structures in the electron beam is discussed.     

On the Generation of Intense Cs K X-Rays upon Electron Excitation of a Mo Target Heat Treated in Cs and O2 Vapors

JETP Letters - The possibility of stable generation of intense characteristic Cs radiation upon electronic excitation of a Mo anode target heat treated in Cs and O2 vapors is demonstrated. The...