Research of a fractional-turn ratio saturable pulse transformer and its application in a microsecond-range pulse modulator

As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.     

基于PLC的110MW脉冲调制器控制器设计

论述了110MW脉冲调制器控制器的设计，简要比较了几种在工业场合中常用的控制器。调制器控制器核心采用PLC可编程控制器。控制器实现了对调制器联锁信号、电路状态信号的实时监测，闸流管预热系统、速调管预热系统等流程的控制，高压恒流充电电源的控制以及与加速器控制室的数据通信。调制器长期运行表明控制器工作稳定、可靠。     

Simulation calculation of 24kV long pulse TESLA modulator

1 Introduction output pulse is designed to meet the following speci- fications: The 24 kV long pulse modulator converts AC line Output voltage: 120 kVvoltage to pulsed high voltage in the 120 kV range to Output current: 138 Abe applied to the Thomson TH1801 multibeam kly- Pulse width: 1.7 msstron catho…     

Temporal characteristic analysis of single event effects in pulse width modulator

In this paper,the nature and origin of single event effects (SEE) are studied by injecting laser pulses into different circuit blocks,combining with analysis to map pulse width modulators circuitry in the microchip die.A time-domain error-identification method is used in the temporal characteristic analysis of SEE.SEE signatures of different injection times are compared.More serious SEE are observed when the laser shot occurs on a rising edge of the device output for blocks of the error amplifier,current sense comparator,and T and SR latches.     

吲哚荷尔蒙自由基脉冲辐解光谱及其酸基平衡和还原电位性质研究

The Absorption spectral, acid-base equilibrium potential properties and formation and decay kinetics of four kinds of radicals from natural existing indole hormones were studied by pulse radiolysis.One of the most important properties for these four indolyl hormones, melatonin, 5-methoxygramine (MTA),5-methoxy-N, N-dimethylthytrytamine (DMM TA) and 5-methoxy-N, N-diethylthytrytamine (DEMT A), which are involved in biochemical processes and play crucial roles in many neuropathy and cancer related diseases, is their facile one electron oxidation with formation of radical cations or their conjugated base, the indolyl radicals.Formation kinetics and properties of the radicals were investigated by pulse radiolysis using the Linac accelerator with fast time-resolving optical system in UTNL.In the present study, these radicals were generated through oxidation of the corresponding hormone with azide radical in radiation induced process. Their spectroscopic properties were investigated and it was found that the transient spectra in all these cases exhibit similar absorption and pH dependence: in acidic solution, the radicals are characterized with three absorption maxima around 320-350, 440-460, 520-550nm. The spectra of MTA at various pH were shown as an example. From the absorption changes as a function of pH, two pK values were determined to be around 5 and 9 for the indolyl radicals except for melatonin, in which, only one pK was distinguished to be 4.4. Formation kinetics of the radicals was measured by following the growth of their absorption peaks and it was found that these indolyl derivatives transfer an electron to N3, with different rate constants, i.e.1.2×1010, 4.5×109, 4.9×109, 1.6×109 dm3 mol-1 s-1 for melatonin, MTA, DMMTA, and DEMTA, respectively.Reduction potentials of the radicals vs their molecules were also determined and they are dependent on the pH of medium. At pH 7, the reduction potentials were estimated to be 1.10, 1.18, 1.18, 1.20eV for melatonin, MTA,DMMTA and DEMTA, respectively. Because of its relatively high contents in human brain cells, melatonin is the main antioxidant among hormones against the oxidizing species in brain cells.     

The spectral, acid-base equilibrium and reduction potential properties of indole hormone radicals ： a pulse radiolysis study

The Absorption spectral, acid-base equilibrium potential properties and formation and decay kinetics of four kinds of radicals from natural existing indole hormones were studied by pulse radiolysis.     

小型电子直线加速器脉冲调制器输出电路的拓扑结构

在小型电子直线加速器中使用各种脉冲调制器输出电路拓扑结构以适应不同的调制器负载要求。对不同的拓扑所遇到的一些共同性问题进行了详尽的叙述与讨论。     

直流高压电源纹波的实验研究

以数字示波器为主要测试设备,提出了从时域、频域、统计域三个角度描述直流高压电源纹波的方法,并分析了时域纹波频谱分析中可能存在的失真问题及解决办法.     

The study of neutron diffusion in beryllium by a pulse method

A pulsed-neutron-source method was used to determine to a high accuracy the diffusion and nuclear characteristics of beryllium: the diffusion coefficient, the diffusion and transport lengths, the mean lifetime, the effective absorption cross section, and the diffusion-cooling coefficient.The article discusses the reasons for the discrepancies between the values obtained by different authors for the diffusion-cooling coefficient.Translated from Atomnaya Énergiya, Vol. 16, No. 3, pp. 224–228, March, 1964     

Design and study of a C-band pulse compressor for the SXFEL linac

A C-band RF pulse compressor is in development at SINAP It comprises of two resonant cavities,two mode convertors and a 3 dB power divider.TE_(0.1.15)mode is selected for obtaining higher quality factor Q_0 of the RF pulse compressor cavities,so that the power gain factor can be 3.2,which is supposed to multiply the RF power from 50 MW to 1 60 MW.In this paper,we report our work on C-band RF pulse compressor,namely the design simulation and cold test results.     

等离子浸没离子注入陡脉冲前后沿效应及控制技术

等离子浸没离子注入过程中,由于电路和负载的容性效应,使高压脉冲电源的输出电压前后沿较长,而高压脉冲的前后沿对离子能量的均匀性、注入深度及剂量分布都有很大影响。本文用硬管调制技术研制最高输出电压40 kV的脉冲电源,并通过一维PIC仿真方法,研究了脉冲后沿对注入离子能量的影响,并从理论上计算不同工艺参数下电源输出电能的利用率。对于前沿,当高压电子管一栅电压为200 V时,获得1μs的高压脉冲前沿时间。对于后沿,用多个IGBT开关串联释放高压脉冲关断后负载上存储的剩余电荷,获得较小的回复时间,实现了对高压脉冲拖尾时间控制。通过PSPICE仿真优化了脉冲后沿控制电路的驱动延迟时间和IGBT吸收电路的参数。     

Results of an integration study of a diagnostics port plug in ITER

Diagnostics in ITER are mandatory to characterize the parameters of plasma and study its interactions with plasma-facing components. Diagnostics components in the vicinity of the plasma are supported by metallic structures called port plugs. At the tokamak mid-plane, these components are installed in port plugs through intermediate structures called drawers. Apart from hosting the diagnostics, the port plugs act as shielding against neutrons and gammas, in order to limit the nuclear loads in crucial components (such as diagnostics and superconducting coils) as well as the dose levels in the controlled zones of the tokamak. The radiation shielding function of the port plugs is ensured through an optimized mixture of heavy metallic materials and water, forming shielding blocks surrounding the diagnostics and called Diagnostic Shield Modules (DSMs). These DSMs constitute the rear part of the drawers (the front part being composed of the Diagnostic First Wall). This paper presents the main results of a study performed in Europe on the integration of a particular diagnostics port plug, the Equatorial Port Plug 1 (EPP1). The paper first provides the results of the EPP1 diagnostics integration analysis. In a second step it focuses on the design of the EPP1 DSMs and summarizes the major results of a thorough set of analyses aiming at studying the DSMs behaviour under different loads, suggesting recommendations to improve their current design.     

数字高斯脉冲成形算法仿真研究

高斯脉冲具有良好的时间、频率响应和较高的信噪比,探测器输出信号通常被滤波成形为高斯波形或类高斯波形。在高斯脉冲成形算法基础上,引入截止频率和品质因子,讨论成形参数对成形脉冲幅度、宽度的影响。通过与梯形脉冲成形算法对比,研究高斯脉冲成形算法的滤波效果以及对核信号幅度谱的作用。结果表明,在相同达峰时间条件下高斯脉冲成形算法具有更好的噪声抑制能力,同时可减小核信号幅度谱的半高宽;结合使用梯形脉冲成形算法可改善高斯脉冲成形算法在处理堆积脉冲中的不足,提高核信号通过率。     

An experimental study of natural convection in a volumetrically heated spherical pool bounded on top with a rigid wall

Flooding of the reactor cavity is being considered as a cooling strategy to prevent vessel thermal failure in the case of severe core damage accidents in which relocation of core material into lower vessel head occurs. A recent study carried out at UCLA showed that the flooding of cavity could indeed be a viable option. However, one important factor contributing to uncertainty in that study was the internal natural convection heat transfer coefficient. In the present work, experiments were conducted to examine natural convection heat transfer in internally heated hemispherical pools with external cooling. In the experiments, Freon-113 contained in a Pyrex bell jar, was used as a test liquid and the vessel was cooled from the outside with water. The pool was bounded with a rigid wall at the top, and was heated with a 750 W magnetron taken from a conventional microwave oven. The vessel inner wall temperature was not held constant and varied from the stagnation point to the equator. A series of chromel alumel thermocouples was used to measure the pool and wall temperatures at different locations.Experiments were performed for pools with nearly insulated and cold rigid walls at the top. The depth of the pool was varied parametrically. Both local and average heat transfer coefficients based on maximum pool temperature were obtained. The results have been compared with the correlations obtained for pools with free surface.     

Optimization of ripple filter for pencil beam scanning

This paper presents a novel approach to seek the bar width for ripple filter used in pencil beam scanning proton therapy. A weight decay quadratic programming method is employed for the new optimization strategy. Compared to the commonly used iterative-least-square technique, the ripple filter derived by the proposed method not only has better depth dose uniformity, i.e., the dose uniformity is within 0.5%, but also has triangle-like vertical cross-sectional shape which is suitable for manufacture. Moreover, the new method has such good robust characteristics that it is also applicable to the real application with unavoidable measurement errors and noises. The simulation results of this study may be helpful in improving the design of the ripple filter.     

Experimental study of pulse neutron irradiation damage in SiGe HBT

The response to transient irradiation of npn SiGe HBT (BG35 SiGe BiCMOS), i.e. device under test (DUT) was studied with online measurement of 1 MeV equivalent pulse neutron fluence of 0.8 × 10¹³n/cm². The differently biased DUT1 and DUT2 in test circuit were irradiated in the first day with neutron fluence (0.8 × 10¹³n/cm²) termed as Fluence1 and with an additional neutron fluence (0.8 × 10¹³n/cm²) in the second day to make Fluence2 equals to 1.6 × 10¹³n/cm². The experimental results show that pulsed neutron irradiation causes voltage surges in the DUTs exhibited by a negative and positive peak known to be radiation damage (RD). The RD in DUTs induced by pulse neutron Fluence1 initially created unstable displacement defects and the defects later reordered (cluster defects) to form more stable configurations via neutron Fluence2. The irradiated DUTs experienced online instantaneous annealing after 2.03 × 10^?9 s and offline measurement (i.e. without irradiation) of DUTs showed recovery to normal mode of operation after 24 h annealing. The level of pulse peaks in the base voltage terminals of DUT1 and DUT2 were compared as V_b2Fluence1 > V_b1Fluence1 and V_b2Fluence2 > V_b1Fluence2. A comprehensive analysis of RD region in DUTs with reference to Area (A₁, A₂), Peak (P₁, P₂), Height (H), and Full width at half maximum (FWHM) were investigated.     

Microwave pulse from a stratospheric explosion

The generation of a microwave pulse by the plasma created by a stratospheric source of ionizing radiation is examined. The structure, the mechanisms for generating the signal, and the information contained in the signal observed at a satellite positioned directly above the explosion are discussed. It is shown that the microwave pulse is generated by two mechanisms: radiation from the shock front lasting up to one second and radiation from a partially ionized plasma lasting tens of microseconds. A package of programs developed by the authors is used for model calculations of microwave pulses. The parameters of the signal are such that they can be picked up by modern pulse radiometers. Translated from Atomnaya énergiya, Vol. 105, No. 3, pp. 156–160, September, 2008.     

On the decrease of the ion pulse duration and ion pulse rate in a cyclotron

Results of calculations and experiments dealing with shortening of the duration of ion pulses on the target of a cyclotron are presented. The possibility of changing the ion pulse rate by deflecting with a high frequency potential applied to an electrode inside the dee, which draws off the ions on the first half turn is discussed.Calculations and experiments were made for the condition of deuteron acceleration up to 10 Mev in the one and one-half meter cyclotron [1].The authors deeply thank N. A. Vlasov, S. P. Kalinin, B. V. Rybakov, and V. A. Sidorov for sustained interest in the work and their joint discussion of it; N. I. Chumakov, V. P. Konyaev, and G. N. Golovanov for making a series of calculations; Yu. V. Korshunov, A. V. Antonov, and E. A. Meleshko for the deisgn and adjustment of the electronic apparatus for the control electrode supply.     

Spectroscopic study of bipolar nanosecond pulse gas-liquid discharge in atmospheric argon

Atmospheric gas-liquid discharge with argon as a working gas is presented by employed nanosecond pulse power. The discharge is presented in a glow-like mode. The discharge powers are determined to be less than 1 W, and remains almost constant when the discharge duration time increases. Bountiful active species are determined by capturing optical emission spectra,and their main generation processes are also discussed. The plasma gas temperature is calculated as 350 K by comparing the experimental spectra and the simulated ones of N_2(C~3Ⅱ_g→B~3Ⅱ_g, Δv =-2). The time resolved vibrational and rotational temperature is researched to present the stability of discharge when pulse voltage and discharge duration vary.The electron density is determined to be 10~(16) cm~(-3) according to the Stark broadening effect of the H_α line.