共查询到20条相似文献,搜索用时 15 毫秒
1.
Sanders J.M. Kuthi A. Yu-Hsuan Wu Vernier P.T. Gundersen M.A. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2009,16(4):1048-1054
A compact pulse generator capable of producing high voltage pulses with halfmaximum widths as short as 2.5 ns and amplitudes as high as 5 kV has been developed to enable current and future in vivo and in vitro research into the effects of ultra-short, intense electric fields on biological matter. This pulse generator is small, simple, and free of saturable magnetic cores, which frequently introduce amplitude jitter and an undesirable correlation between amplitude and pulse width. In place of a non-linear pulse-forming network is a single-stage resonant network that drives a bank of junction recovery diodes. The diodes function as an opening switch that commutes current from an inductor to a resistive load. The use of air-core inductors in the resonant network results in a stable output pulse with an amplitude that scales linearly with input voltage and a pulse width that is independent of amplitude. The ability to scale the output amplitude independently of the pulse width simplifies the setup for experiments that require pulses with different electric field strengths but the same rise time and duration. Jurkat T lymphoblast cells exposed to 2.5 ns fields produced by this pulse generator showed an increasing degree of electropermeabilization with increasing pulse dosage and electric field intensity. 相似文献
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Tao Tang Fei Wang Kuthi A. Gundersen M.A. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):878-883
Studies of short (few ns) pulse cell electroperturbation require high-voltage nanosecond pulses delivered to low-impedance (10 Omega) electroporation cuvette loads. Here we present two pulse generators for these applications. The generators comprise of three stages of pulse modulation: an LC resonant stage switched by IGBT/MOSFET; a magnetic pulse compression stage; and a diode opening switch output stage. The all-solid-state design results in reproducible pulses and reliable, long-life operation. Pulses produced by the LC resonant stage are compressed using nonlinear properties of the magnetic material. The compressed pulses are fed to the diode opening switch, which is constructed by series and parallel connecting ordinary automotive rectifying diodes. Two versions of the pulse generator are described: The first version is capable of generating 20 ns wide, 4.5 kV amplitude pulses of 20 Hz repetition rate. A second version generates 5 ns, 7.5 kV amplitude pulses into the same 10 Omega cuvette load. 相似文献
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Krishnaswamy P. Kuthi A. Vernier P.T. Gundersen M.A. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):873-877
Research on the electroperturbation effects of ultrashort high field pulses in cancer cells requires subnanosecond rise time, high voltage pulses delivered to low impedance biological loads. Here we present a compact solid-state pulse generator developed for this application. The pulse is generated by switching a chain of avalanche transistors configured as a tapered transmission line from high voltage to ground. The system features a built in 1400:1 capacitively compensated resistive voltage divider. The divider, with a 3 dB point at 910 MHz, overcomes challenges in the direct measurement of the high frequency components of the output pulse. The generator is capable of producing a 0.8 ns rise time, 1.3 ns wide, 1.1 kV pulse into a 50 Omega load at a maximum repetition rate of 200 kHz. Techniques to implement physical layouting strategies to achieve subnanosecond rise times are outlined. Problems faced in integrating the subnanosecond pulse generator with a biological load are discussed. This pulse generator will be used in experiments aimed at electromanipulation of intracellular biomolecular structures. 相似文献
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重频纳秒脉冲激励的大气压等离子体放电具有反应活性高等优点。设计了基于模块化雪崩三极管Marx电路和传输线变压器的重频纳秒脉冲源。计算不同Marx模块的导通时延和输出波形的抖动,研究了磁心数量、位置和形状对于输出波形的影响。磁心电感越大、外径与内径之比越大,且位于传输线变压器第一级和最高一级时对脉冲叠加效率的提升作用越明显。提出直接叠加和传输线变压器两种脉冲叠加方式组合的方法,进一步提高输出电压。整体脉冲源可以在50~300Ω负载产生2~14k V,高阻负载产生4~25k V,前沿3.8ns,脉宽7~15ns,重复频率0~10k Hz的重频纳秒脉冲电压,装置结构紧凑,参数调节灵活,方便携带。 相似文献
5.
Eing C.J. Bonnet S. Pacher M. Puchta H. Frey W. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2009,16(5):1322-1328
Seven days old seedlings of Arabidopsis thaliana, suspended in a 0.4 S/m buffer solution were exposed to nanosecond pulsed electric fields (nsPEF) with a duration of 10 ns, 25 ns and 100 ns. The electric field was varied from 5 kV/cm up to 50 kV/cm. The specific treatment energy ranged between 100 J/kg and 10 kJ/kg. Due to electroporation of the plasmamembrane of the plant cells, the seedlings completely died off, when 100 ns pulses and high electric field pulses were applied. But even at the highest specific treatment energies, 10 ns pulses had no lethal effect on the seedlings. An evaluation of the leaf area 5 and 7 days after pulsed electric field treatment revealed values twice the area of sham treated seedlings up to a specific treatment energy of 4 kJ/kg, when the applied field amplitude was low or the pulse duration 10 ns. A growth stimulating effect after short pulse exposition clearly could be detected. Contrary to the growth inhibiting effect of plasmamembrane electroporation on the seedlings, a growth stimulation by nsPEF treatment does not scale with the treatment energy within the applied parameter range. 相似文献
6.
为了给非平衡等离子体相关实验提供ns级高压脉冲,研制了一台基于传输线变压器(transmission linetransformer,TLT)原理的高压重频ns脉冲电源,通过在传输线外套加磁环增加二次阻抗,提高TLT的输出电压和能量传输效率。同时设计了一种电容-开关-传输线的紧凑化同轴结构。实验表明,在连接匹配负载条件下,电源输出脉冲电压峰值可以达到26kV,脉宽100ns,上升时间25ns,可在500Hz频率下稳定运行。同时成功地将其应用于大气压氩气等离子射流实验,发现与正弦电压相比,相同电压峰值下,脉冲电源作用下的等离子体射流长度更长,但2种电源作用下的射流长度均出现饱和现象,同时电源频率对射流长度无明显影响。 相似文献
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为进行绝缘材料在快前沿高压脉冲作用下的局部放电和绝缘老化的试验研究,研制了1台最高输出电压为10kV的重复频率高压方波脉冲发生器。该方波发生器采用可调直流高压电源和储能电容器作为能源系统,利用半导体固态开关作为主放电开关控制脉冲宽度和重复频率,通过脉冲放电回路在负载上形成所需的电压脉冲。其半导体固态开关采用具有低耦合电容的紧凑型快速高压金属氧化层半导体场效应晶体管(MOSFET)开关,通过复杂可编程逻辑控制器(CPLD)可编程逻辑电路实现开关通断控制。实测结果表明,该脉冲源可以产生脉冲上升沿约为80ns、最小脉冲宽度为320ns的高压准方波脉冲,最高输出幅值达到±10kV,脉冲重复频率的可调范围为1~3kHz,性能指标满足绝缘材料的局部放电以及绝缘老化试验的要求。 相似文献
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Buescher E.S. Schoenbach K.H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2003,10(5):788-794
Development of technology to produce nanosecond duration pulsed electric fields has allowed examination of the effects of ultrashort duration, high intensity electric fields on living cells. Theoretically, high intensity (MV/m) electric field applications with durations of less than one microsecond, when shortened toward nanoseconds, should increasingly affect intracellular rather than surface membranes of living cells. Experimentally, square-wave, 60 ns duration, high energy (36-53 kV/cm) pulses applied in trains of 1-10 pulses result in progressive increases in the numbers of permeabilized intracellular granules in a human eosinophil cell model-without large surface membrane effects. Electron micrographic examination of cells treated in this way demonstrates alteration of intracellular granule morphology consistent with permeabilization of granule membrane, i.e., intracellular electromanipulation. Continuous microscopic examination of individual living cells exposed to long or short duration pulsed electric field applications shows that permeabilization of surface membrane (median 5 minutes) with anodic preference (electroporation) and prompt cellular swelling follow a single, long duration (100 microsecond) pulse. In contrast, after a single short duration (60 ns) pulse, onset of surface membrane permeability is delayed (median 17 minutes), the increased permeability shows no anodic preference, and cellular swelling is absent suggesting that these effects are due to intracellular electromanipulation rather than direct effects on the surface membrane. Submicrosecond, intense pulsed electric fields applied to living cells achieve preferential effects on intracellular rather than surface membranes, potentially providing new approaches for selective/generalized cell or tissue ablation, growth stimulation and tissue remodeling. 相似文献
10.
设计了一种新型的超宽带ns级低过冲平衡脉冲发生器.该脉冲发生器包含驱动电路、雪崩三极管脉冲电路和脉冲整形电路3部分,驱动电路用以锐化触发脉冲;雪崩三极管脉冲电路采用独特的晶体管级联结构产生大幅度的高斯脉冲;脉冲整形电路利用并联端接电阻网络和肖特基二极管减小信号反射,最后使用巴仑产生平衡的高斯脉冲,该电路最高可以在300 KV脉冲重复频率下正常工作.测量结果表明,在100 KV脉冲重频时该脉冲发生器可以输出一对峰峰值为230 V、前沿为1.3 ns的平衡脉冲,并有着极小的振铃和过冲.这些特征说明,该脉冲发生器在探地雷达应用中有着更深探测距离和更快数据处理速度的优势. 相似文献
11.
Rui Liu Xinxin Wang Xiaobing Zou Naigong Zeng Luya He Xiao Liu 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):889-893
The load section of a pulsed power generator for X-pinch was designed. It is a work that repeats itself in cycles as follows: making small changes in size and configuration of the electrode system in order to reduce inductance rarr calculating the inductance rarr calculating the load voltage with the measured forward going voltage wave along the pulse transmission line (PTL) incident upon the load rarr calculating the electric field rarr checking if any surface flashover or breakdown in vacuum happens. In the final designed load section, the highest field on the surface of the insulator, a plexiglass diaphragm, is 113 kV/cm and the highest field in vacuum is 298 kV/cm, respectively lower than the surface flashover voltage and the vacuum breakdown voltage in case of an applied pulse voltage of 100 ns of full width at half maximum (FWHIVI) and 500 kV in amplitude. 相似文献
12.
Minamitani Y. Ohe Y. Higashiyama Y. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):894-899
Nanosecond and sub-nanosecond high voltage pulses can provide new applications. A cancer treatment by an ultra-short pulse high electric field is one of them. High power pulsed microwave has been proposed to apply the high electric field for that treatment. This work focuses on the design of a compact high power pulsed microwave generator using a nanosecond pulse power generator for the cancer treatment. To obtain fast rise time of voltage and current for nanosecond pulses, a switch has to have low inductance. Water gap switches have this property. Since water has a dielectric strength exceeding 1 MV/cm, gap distances for switching can be reduced to several hundreds of micrometers, and still allow switching of tens of kV. The narrow gaps allow us to reduce the switch inductance. In this study, the water gap switch was built in a Blumlein pulse forming line. The Blumlein line was designed to provide a pulse of 1 ns and to match an impedance to 16 Omega of an antenna. By using the water gap switch in the Blumlein line, the voltage rise time obtained approximately 750 ps at 13 kV of a peak pulse voltage. An electromagnetic wave was radiated underwater by the loop antenna. A measuring antenna at 0.15 m and 0.4 m from the radiating antenna caught electric field intensities of 116 kV/m and 32 kV/m, respectively. A frequency element of 250 MHz had higher intensity. 相似文献
13.
S. V. Pustynnikov 《Russian Electrical Engineering》2016,87(1):35-40
To obtain the current pulses applied to the active load, the circuit breaking effect has been used in the primary winding of the pulse transformer. When the direct current voltage source is disconnected, the current of primary winding is reduced to zero, so that a current pulse is formed in the secondary winding of the pulse transformer that is transmitted into the load. A circuit of the inductive pulse generator operating on the basis of generalized switching laws was developed so as to increase the amplitude of current pulses in the active load and the corresponding power. The circuit contains a pulse transformer, the secondary winding of the pulse transformer is connected to the load, and an additional inductor is connected parallel to the primary winding of the pulse transformer. When the direct current voltage source is disconnected, the current of primary winding passes through zero and decreases to a negative value, which leads to a significant increase in the current pulse in the load. In accordance with the generalized law of commutation, the relationships for the calculation of the current jump of pulse transformer primary winding and a jump in the load current have been obtained. Using the state-space technique, mathematical models of the circuits mentioned above with linear active load have been developed. Theoretical and experimental studies have shown a significant increase in the current pulse value and its capacity in the active linear load when the inductive pulse generator has been used. The values of currents in inductive coils detected experimentally were practically the same as the calculated values. 相似文献
14.
Sun Y. Xiao S. White J.A. Kolb J.F. Stacey M. Schoenbach K.H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):863-870
The high dielectric strength and high permittivity of water allow for its use for energy storage and switching in compact pulse power systems. A 10-Omega pulse generator with flowing water as dielectric and as the switching medium is presented here. It can provide a 10-ns pulse with a risetime of approximately 2 ns and an amplitude of up to 35 kV into a matched load. The system was operated in burst mode with repetition rates of up to 400 Hz, limited by the charging power supply. For a switch with two pin electrodes, strong electrode erosion limits the use of the pulser to less than 1,000 pulses before electrode readjustment is necessary. A considerable reduction of the erosion effect on breakdown voltage was obtained with coaxial electrodes. The pulse generator was used to study the effect of the repetition rate (or the time between successive pulses) on the viability of B16 murine melanoma cells. 相似文献
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Tao Shao Guangsheng Sun Ping Yan Shichang Zhang 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(4):813-819
Nanosecond-pulse breakdown indicates special characteristics depending on the pulse rise-time and duration. Based on a repetitive nanosecond-pulse generator, breakdown phenomena of parallel-plane gaps in nitrogen were investigated with single pulse and repetitive bursts under different gap conditions. The relationships between applied voltage, pulse repetition frequency, breakdown time lag, repetitive pulse stress time and the number of applied pulses are presented. The curves regarding E-field strength, breakdown time lag and gas pressure are also obtained. The experimental results show that breakdown characteristics with repetitive nanosecond-pulses are different from that with single pulse. Repetitive nanosecond-pulse breakdown is concerned with the accumulation effect that is attributed to residual ions and metastable species survived from previous pulses. In addition, a modified empirical formula about E-field strength, breakdown time lag and gas density is given for the breakdown data. 相似文献
18.
S. Bamji M. Abou Dakka A. Bulinski 《Dielectrics and Electrical Insulation, IEEE Transactions on》2007,14(1):77-82
The PEA technique has been modified to study the space charge development in solid dielectrics subjected to AC electric field. Narrow (5 ns) electrical pulses are applied at various phase angles of the AC waveform. Special software, developed to precisely synchronize the pulse generator with the high voltage supply, applied the narrow pulses at 0deg phase angle and then in steps of 10deg till 360deg. By processing the PEA data at various phase angles of the AC waveform, without resorting to complex mathematical analysis, the electric field at which charges are injected into the polymeric insulation was determined. The phase resolved PEA technique can also provide the dynamics of space charge development under AC fields 相似文献
19.
针对柴电机组在低功率负载时柴油机工作汽缸数目变化,会导致柴油机轴旋转频率降低从而恶化电能质量的问题,根据异步化同步发电机的工作原理,通过分析得出了异步化同步发电机稳态等效电路及稳态方程的解析解。通过对异步化同步发电机励磁装置的分析表明,当采用带高频载波、宽脉冲调制的自主式电压逆变器励磁时,在恒定载波频率下,改变调制深度系数及调制频率可以实现励磁绕组电流频率和电压的独立调节,从而可以控制输出电压的幅值和频率,保证电能性能指标在容许的范围内。因此采用异步化同步发电机来代替普通同步发电机,既能降低燃油单位消耗又能保证电能质量良好。 相似文献
20.
孤岛电网是一种容量较小、频率和电压稳定度较差的特殊电网。文中针对此类电网运行情况,利用基于晶闸管的柔性电负荷平衡装置,建立一种考虑负荷端与发电机端协同出力的调频模型。采用ETAP仿真平台对苏拉威西某工业园电力系统使用不同调频模型的效果进行了仿真对比分析,结果表明:当系统突甩大负荷时,相对发电机单独调频模型,负荷端与发电机端协同出力的调频模型可使得系统频率波动更小,稳定频率更接近额定频率;当系统将接入大负荷时,提前投入电负荷平衡装置可以避免系统频率断崖式下跌,将频率下跌过程进行拆分,缓解系统内设备的压力。 相似文献