Thermal sensitive paper as a diagnostic for intense relativistic electron beam dynamics

Thermal sensitive paper has been used as a diagnostic for an intense relativistic electron beam propagating in a rippled magnetic field. The E(r)xB(z) rotation of the beam has been measured from the exposed pattern on the thermal paper and used to calculate the electrostatic field of the beam E(r), and the corresponding values of electron density and beam current. Exposed strips of thermal paper show longitudinal modulation of the radial electron velocity with a period corresponding to that of a rippled magnetic field; modulation of the radial electron velocity at the cyclotron frequency has also been observed.     

High-intensity vacuum ultraviolet continuum emission from intense relativistic electron rings

Intense relativistic electron rings can emit a high-intensity continuum in the vacuum ultraviolet spectral region if the ring parameter range is moderately extended beyond the values used at present in electron ring accelerators. Although the ring dimensions are very much smaller than those of conventional accelerators and storage rings acting as synchrotron radiation sources, the electron current in the rings can be made very high, being limited only by collective instability thresholds and technical constraints, so that electron rings can afford a relatively cheap source of high-intensity vacuum ultraviolet radiation with a continuous spectrum. The radiation is pulsed with a duration of about 100 μs, and even with a repetition rate of about 10 Hz the time-averaged brightness of this source could be higher in the VUV region than that of present storage rings.     

K-line spectra from tungsten heated by an intense pulsed electron beam

The plasma-filled rod-pinch diode (PFRP) is an intense source of x-rays ideal for radiography of dense objects. In the PRFP megavoltage electrons from a pulsed discharge concentrate at the pointed end of a 1 mm diameter tapered tungsten rod. Ionization of this plasma might increase the energy of tungsten's Kα(1) fluorescence line, at 59.3182 keV, enough for the difference to be observed by a high-resolution Cauchois transmission crystal spectrograph. When the PFRP's intense hard bremsstrahlung is suppressed by the proper shielding, such an instrument gives excellent fluorescence spectra, albeit with as yet insufficient resolution to see any effect of tungsten's ionization. Higher resolution is possible with various straightforward upgrades that are feasible thanks to the radiation's high intensity.     

Coupled Marx-Tesla circuit for production of intense relativistic electron beams

A two-stage Marx circuit was built and is used to multiply the input energy of our Tesla resonant transformer accelerator without missing resonance conditions. The present output characteristics of our coupled Marx-Tesla circuit are compared to those of the previous Tesla transformer. With the same input voltage and cathode to anode distance, we succeeded in doubling output voltage and current of the beam.     

Measurements of the profile of an intense electron beam

Methods for measuring the profiles of high-power electron beams by using a thin tungsten wire moved transversely to the beam have been developed. In one method, the electron current intercepted by the wire is measured and the beam profile is determined from a solution to the Abel equation under the assumption of axial beam symmetry. The second method is based on the detection of the local radiation emitted by the wire being heated by the beam to 1700–2200 K. The wire is additionally heated by an electric current in order to improve the sensitivity and spatial resolution. The measured beam current density is ～5–50 A/cm², and the resolution is ～0.1 cm.     

Electron cyclotron resonance plasma production by using pulse mode microwaves and dependences of ion beam current and plasma parameters on the pulse condition

We measure the ion beam current and the plasma parameters by using the pulse mode microwave operation in the first stage of a tandem type ECRIS. The time averaged extracted ion beam current in the pulse mode operation is larger than that of the cw mode operation with the same averaged microwave power. The electron density n(e) in the pulse mode is higher and the electron temperature T(e) is lower than those of the cw mode operation. These plasma parameters are considered to cause in the increase of the ion beam current and are suitable to produce molecular or cluster ions.     

SRG风力发电系统最大风能追踪控制研究

针对在实验室条件下实现SRG风力发电系统的最大风能追踪控制的问题,对风力机的运行特性及其模拟实现方案、开关磁阻电机的工作原理及其控制方法等方面进行了研究,并对风力发电系统中实现最大风能追踪的控制策略进行了介绍,提出了基于转速反馈的SRG发电系统最大风能追踪控制方案,同时对直流电机进行了转矩控制以实现风力机输出特性的模拟.在SRG风力发电系统平台上对风力机模拟系统进行了测试评价,并进行了变风速条件下的最大风能追踪试验.研究结果表明,直流电机能够有效模拟风力机的输出特性,控制简单,抗干扰能力强,基于转速反馈的MPPT控制方法能够在风速变化时快速调节SRG输出,准确地实现最大风能跟踪.     

Nanosecond response 'gasket-type' magnetic loop current monitor for relativistic electron beam current measurements

A fast response magnetic loop current monitor has been developed to measure relativistic electron beam return currents. The monitor has a rise time of about a nanosecond and a high degree of symmetry with moderate sensitivity, variable from about 1 to 10 V/kA. This simple monitor, with a thickness of 0.254 mm or less, is thin enough to be placed between segments of return current path in the diode or drift tube regions, is insensitive to flashover, beam and plasma bombardment, and radiation effects, and measures net current, thus offering some advantages over conventional magnetic probes, since the main components are outside of the vacuum region. Design criteria, an equivalent circuit analysis, and typical calibration waveforms are presented. Experimental current measurements for a pinched electron beam diode configuration using both conventional magnetic probes and 'gasket-type'current monitors with the FX-75 relativistic electron beam accelerator are presented.     

Compact inductive energy storage pulse power system

An inductive energy storage pulse power system is being developed in BARC, India. Simple, compact, and robust opening switches, capable of generating hundreds of kV, are key elements in the development of inductive energy storage pulsed power sources. It employs an inductive energy storage and opening switch power conditioning techniques with high energy density capacitors as the primary energy store. The energy stored in the capacitor bank is transferred to an air cored storage inductor in 5.5 μs through wire fuses. By optimizing the exploding wire parameters, a compact, robust, high voltage pulse power system, capable of generating reproducibly 240 kV, is developed. This paper presents the full details of the system along with the experimental data.     

Fractional order fuzzy control of hybrid power system with renewable generation using chaotic PSO

This paper investigates the operation of a hybrid power system through a novel fuzzy control scheme. The hybrid power system employs various autonomous generation systems like wind turbine, solar photovoltaic, diesel engine, fuel-cell, aqua electrolyzer etc. Other energy storage devices like the battery, flywheel and ultra-capacitor are also present in the network. A novel fractional order (FO) fuzzy control scheme is employed and its parameters are tuned with a particle swarm optimization (PSO) algorithm augmented with two chaotic maps for achieving an improved performance. This FO fuzzy controller shows better performance over the classical PID, and the integer order fuzzy PID controller in both linear and nonlinear operating regimes. The FO fuzzy controller also shows stronger robustness properties against system parameter variation and rate constraint nonlinearity, than that with the other controller structures. The robustness is a highly desirable property in such a scenario since many components of the hybrid power system may be switched on/off or may run at lower/higher power output, at different time instants.     

High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system

High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20°-40° from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system.     

An electron beam lithography and digital image acquisition system for scanning electron microscopes

A low‐cost microcontroller based control and data acquisition unit for digital image recording of scanning electron microscope (SEM) images and scanning electron microscope based electron beam lithography (EBL) is described. The developed microcontroller low‐level embedded software incorporates major time critical functions for image acquisition and electron beam lithography and makes the unit an intelligent module which communicates via USB with the main computer. The system allows recording of images with up to 4096 × 4096 pixel size, different scan modes, controllable dwell time, synchronization with main power frequency, and other user controllable functions. The electron beam can be arbitrary positioned with 12‐bit precision in both dimensions and this is used to extend the scanning electron microscope capabilities for electron beam lithography. Hardware and software details of the system are given to allow its easy duplication. Performance of the system is discussed and exemplary results are presented.     

High resolution extreme ultraviolet spectrometer for an electron beam ion trap

An extreme ultraviolet spectrometer has been developed for spectroscopic studies of highly charged ions with an electron beam ion trap. It has a slit-less configuration with a spherical varied-line-spacing grating that provides a flat focal plane for grazing incidence light. Alternative use of two different gratings enables us to cover the wavelength range 1-25 nm. Test observations with the Tokyo electron beam ion trap demonstrate the high performance of the present spectrometer such as a resolving power of above 1000.     

Personal-computer-based system for electron beam X-ray microanalysis of biological samples

A system based on a personal computer has been developed which provides a relatively inexpensive way to equip an electron microscopy laboratory for quantitative elemental analyses of cryosectioned biological samples. This system demonstrates the feasibility of making an X-ray analyser from a personal computer, together with commercially available hardware and software components. Hardware and software have been assembled to drive the beam in a scanning electron microscope, collect and analyse X-ray spectra, and save, retrieve, and analyse data. Our software provides a menu-controlled user interface to direct spectra acquisition and analysis. Spot analyses, video images, and quantitative elemental images may be obtained and results transferred in ASCII format to other computers. Wet weight, as well as dry weight, concentrations are calculated, if measurements were made of areas of the hydrated sample before it was freeze-dried. Grey-level copies of video and quantitative elemental images may be made on a laser printer.     

秸秆发电燃料输送系统

开发和利用拥有巨大资源保障、环境友好的替代能源是事关我国国民经济可持续发展、国家安全和社会进步的重大课题,生物质发电主要是利用农业、林业和工业废弃物为原料,采取直接燃烧或气化的发电方式,燃料的输送系统是关系到秸杆发电能否顺利运行的关键。     

Quasianamorphic optical imaging system with tomographic reconstruction for electron beam imaging

We have developed a quasianamorphic optical tomography system coupled to a streak camera to provide continuous recording of the electron beam profile of an intense, long-pulse induction accelerator. A tomographic reconstruction method based on a maximum-entropy algorithm is used to reconstruct the images. The system has simplified the calculation of beam moments, eliminated ambiguity due to beam motion, and contributed to accelerator tuning.     

电子束焊接温度场实时监测系统设计

焊接温度场是影响焊接质量和生产效率的主要因素,因此对焊接过程中的温度场分布进行监测就显得极为重要。利用普通彩色CCD构成了焊接温度场实时测量系统;基于工件热辐射随温度变化单调上升特性建立了温度场测量模型;采用最小二乘法对实测的温度数据进行分析,得到了温度场测量模型的最佳参数。试验结果表明了该监测系统的可行性。     

Determination of the energy of a relativistic electron beam by measuring the thickness of the colored layer in glass

A method for determining the energy of relativistic electrons, which was used in the investigation of electromagnetic fields in plasma and dielectric structures, is described. The electron energy was determined by the extrapolated track of electrons in glass, which was estimated by the thickness of the colored (darkened) layer formed by electrons. The density distribution of the colored layer along the direction of electron motion makes it possible to record the width of the beam energy spectrum and the beam position relative to the axis of the transit channel. A stack of glass plates on which the beam is incident can be installed in the transit channel of the dielectric structure or in plasma. Each plate in the stack is placed in parallel to the beam axis. After irradiation of the plates with relativistic electrons, the colored layer depth and the density distribution are determined. Examples of determining the electron energy of a pulsed relativistic electron beam are presented. The method is insensitive to electromagnetic noise, is inexpensive, simple, and easy to use.     

Post‐thinning using Ar ion‐milling system for transmission electron microscopy specimens prepared by focused ion beam system

We investigate Ar ion‐milling rates and Ga‐ion induced damage on sample surfaces of Si and GaAs single crystals prepared by focused ion beam (FIB) method for transmission electron microscopy observation. The convergent beam electron diffraction technique with Bloch simulation is used to measure the thickness of the Ar‐ion milled samples to calculate the milling rates of Si and GaAs single crystals. The measurement shows that an amorphous layer is formed on the sample surface and can be removed by further Ar‐ion milling. In addition, the local symmetry breaking induced by FIB is investigated using quantitative symmetry measurement. The FIBed‐GaAs sample shows local symmetry breaking after FIB milling, although the FIBed‐Si sample has no considerable symmetry breaking.     

Direct measurement of electron beam scattering in the environmental scanning electron microscope using phosphor imaging plates

Phosphor imaging plate technology has made it possible to directly image the distribution of primary beam electrons and scattered electrons in the environmental scanning electron microscope. The phosphor plate is exposed under electron scattering conditions in the microscope chamber. When processed, the electron intensity distribution is displayed as a digital image. The image is a visual representation of the electron probe and skirt and may provide the basis for a more accurate model.