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2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics最新文献

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Experimental and Theoretical Analyses of Explosively-Formed Fuse (EFF) Opening Switches 爆炸成形熔丝(EFF)开路开关的实验与理论分析
D. Tasker, J. Goforth, H. Oona, Gerald Kiuttu, Matthew Domonkos
The EFF is used at Los Alamos as the primary opening switch for high current applications. It has interrupted currents from ~10 kA to 25 MA, thus diverting the current into low inductance loads. To understand and optimize the performance of full-scale experiments, many parameters were studied in a series of small-scale experiments, including: electrical conduction through the explosive products; current density; explosive initiation; insulator type; conductor thickness; conductor metal; metal temper; and on. The results show a marked inverse correlation of peak EFF resistance with current density. In this paper we postulate and refute a simple extrusion mechanism of EFF operation; demonstrate that the EFF switch has a near-ideal profile for producing flat-topped voltage profiles; and explore possible mechanisms for the degradation of small scale switch performance.
EFF在洛斯阿拉莫斯被用作大电流应用的主要开路开关。它中断电流从~10 kA到25 MA,从而将电流转移到低电感负载。为了了解和优化全尺寸实验的性能,我们在一系列小尺寸实验中研究了许多参数,包括:通过爆炸产物的电导率;电流密度;起爆;绝缘子类型;导体厚度;导体金属;金属的脾气;等等。结果表明,EFF峰值电阻与电流密度呈显著的负相关。本文假设并反驳了一种简单的EFF运行挤压机制;证明EFF开关具有近乎理想的轮廓,用于产生平顶电压轮廓;并探讨小尺度开关性能退化的可能机制。
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引用次数: 3
The Quest for the Wholly Stable Liner 寻求完全稳定的班轮
W. Atchison, P. Turchi, D. Lemons
For several decades many have studied or conducted experiments to drive magnetic fields into metallic conducting materials. Examples include designs for electrically exploded fuses, exploding wires to generate high energy plasmas, and of course heavy metal liners as kinetic drivers for hydrodynamic experiments. When the material melts the surface can develop highly unstable dynamics. One of the most common results is the onset and growth of spatial perturbations taking on the form of spike and bubble like structures. This is usually identified as Magneto-Raleigh-Taylor (MRT) instability. A clear example is when excessive current is applied to accelerate a near normal density thick metal liner to velocities approaching 1.0 cm/musec or greater. Yet we have observed several experiments where melting of the liner was present but the outside liner surface was observed to remained stable (B-0.5 to 1.3 MG). Analysis of this and other cases compared to MHD simulations enabled us to examine this phenomenon under a variety of conditions. While the majority of the cases still are fundamentally acceleration driven instability of a fluid interface, other phenomenon have been observed to play a significant role such as the effect of liquid/vapor phase change at the surface. Additionally, this suggests there may be drive conditions that can maintain the aluminum at conditions well away from the saturated liquid line until the conditions are well above the triple point in aluminum. There are some indications that this may reduce or delay the MRT like instabilities. However excessive drive that pressurizes the melted layer too much produces unfavorable gradients in the material that grossly aggravate the traditional MRT instabilities. In this talk we will examine in detail the effects of EOS structure, conductivity dependence on state properties (e.g. density and temperature), and the magnitude and time dependence of the driving magnetic field on the evolution of surface conditions. Based on these observations we propose that controlling the surface stability may depend on careful adjustment of time scales associated with the driving waveform and kinetics of the liner in order to control the path in phase space (EOS) the material follows.
几十年来,许多人研究或进行了将磁场注入金属导电材料的实验。例子包括电爆炸保险丝的设计,爆炸电线产生高能等离子体,当然还有重金属衬里作为流体动力学实验的动力驱动器。当材料熔化时,表面会产生高度不稳定的动力学。最常见的结果之一是空间扰动的开始和增长,呈现出尖峰和泡状结构的形式。这通常被认为是磁-罗利-泰勒(MRT)不稳定性。一个明显的例子是,当施加过大电流时,将接近正常密度的厚金属衬里加速到接近1.0厘米/平方米或更大的速度。然而,我们已经观察到几次实验,其中衬垫熔化,但衬垫外表面保持稳定(B-0.5至1.3 MG)。与MHD模拟相比,对这种情况和其他情况的分析使我们能够在各种条件下检查这种现象。虽然大多数情况下基本上仍然是由流体界面的加速度驱动的不稳定性,但已经观察到其他现象起着重要作用,例如表面的液/气相变化的影响。此外,这表明可能存在驱动条件,可以使铝保持在远离饱和液体线的条件下,直到条件远远高于铝的三相点。有一些迹象表明,这可能会减少或延迟MRT的不稳定性。然而,过度的驱动使熔化层压力过大,在材料中产生不利的梯度,严重加剧了传统MRT的不稳定性。在这次演讲中,我们将详细研究EOS结构的影响,电导率对状态属性(例如密度和温度)的依赖,以及驱动磁场对表面条件演变的大小和时间依赖。基于这些观察,我们提出控制表面稳定性可能取决于与驱动波形和线性动力学相关的时间尺度的仔细调整,以控制材料在相空间(EOS)中的路径。
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引用次数: 1
A Bench Top Railgun with Distributed Energy Sources and Diagonostics 具有分布式能源和诊断的台式轨道炮
B. McDaniel, J. Mankowski, D. Wetz, B. Mchale, M. Kristiansen
The experimental results of a five stage distributed energy source railgun are presented. The advantages of such a scheme are increased efficiency due to less energy remaining in the railgun inductance and lower rail resistive losses. The design is a bench top 81 cm long solid armature railgun with a 1.27 cm × 1.27 cm bore cross-section separating the 1.27 cm × 2.54 cm copper rails. Multiple capacitive storage banks are connected at different positions along the length of the rails. Each bank is composed of electrolytic capacitors, toroidal inductors, SCRs, and free-wheeling diodes. The primary bank (stage 1) can store 11.6 kJ, and the other stages store 5.8 kJ of energy. The diagnostics include Rogowski coils at each bank, a flux ruler along the entire railgun to monitor the armature's velocity, and B-dots. The switches are controlled by pulsers with fiber optic inputs, which accurately trigger the SCRs. To sequence trigger the storage banks, B-dot sensors provide feedback to the armature's position. Additionally, experimental results are compared to PSPICE simulations.
介绍了一种五级分布式能量轨道炮的实验结果。这种方案的优点是由于轨道炮电感中剩余的能量较少而提高了效率,并且降低了轨道电阻损耗。该设计是一种台式81厘米长的实心电枢轨道炮,直径为1.27厘米× 1.27厘米,横截面为1.27厘米× 2.54厘米的铜轨。沿着导轨的长度在不同位置连接多个电容存储组。每一组由电解电容器、环形电感、可控硅和自由旋转二极管组成。初级库(阶段1)可以存储11.6 kJ的能量,其他阶段存储5.8 kJ的能量。诊断包括在每一排的Rogowski线圈,沿着整个轨道炮的通量尺来监测电圈的速度,以及b点。开关由光纤输入脉冲控制,精确触发可控硅。序列触发存储库,b点传感器提供反馈到电枢的位置。并将实验结果与PSPICE模拟结果进行了比较。
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引用次数: 4
Algorithm for Unfolding Current from Faraday Rotation Measurement 法拉第旋转测量展开电流的算法
S. E. Mitchell
Various methods are described to translate Faraday rotation measurements into a useful representation of the dynamic current under investigation[1]. For some experiments, simply counting the "fringes" up to the turnaround point in the recorded Faraday rotation signal is sufficient in determining the peak current within some allowable fringe uncertainty. For many other experiments, a higher demand for unfolding the entire dynamic current profile is required. In such cases, investigators often rely extensively on user interaction on the Faraday rotation data by visually observing the data and making logical decisions on what appears to be turnaround points and/or inflections in the signal. After determining extrema, inflection points, and locations, a piece-wise, ¿I/¿t, representation of the current may be revealed with the proviso of having a reliable Verdet constant of the Faraday fiber or medium and time location for each occurring fringe. In this paper, a unique software program is reported which automatically decodes the Faraday rotation signal into a time-dependent current representation. System parameters such as the Faraday fiber's Verdet constant and number of loops in the sensor are the only user-interface inputs. The central aspect of the algorithm utilizes a short-time Fourier transform (STFT) which reveals much of the Faraday rotation's hidden detail necessary for unfolding the dynamic current measurement.
描述了各种方法将法拉第旋转测量转化为正在研究的动态电流的有用表示[1]。对于某些实验,简单地计算“条纹”直到记录的法拉第旋转信号的转折点,就足以在一些允许的条纹不确定性范围内确定峰值电流。对于许多其他实验,对展开整个动态电流分布图的要求更高。在这种情况下,研究人员通常广泛依赖于用户对法拉第旋转数据的交互,通过视觉观察数据并对信号中的周转点和/或拐点做出逻辑决策。在确定了极值、拐点和位置之后,在具有法拉第光纤或介质的可靠Verdet常数和每个发生条纹的时间位置的前提下,可以揭示电流的分段表示。本文报道了一种独特的软件程序,可自动将法拉第旋转信号解码为随时间变化的电流表示。系统参数,如法拉第光纤的Verdet常数和传感器中的环路数量是唯一的用户界面输入。该算法的核心方面利用短时傅里叶变换(STFT),揭示了展开动态电流测量所需的法拉第旋转的许多隐藏细节。
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引用次数: 0
Cooling and Condensation of Hydrogen Isotopes in Isentropic Compression Device 等熵压缩装置中氢同位素的冷却和冷凝
G. V. Boriskov, A. Bykov, N. Egorov, V. Pavlov
A compression facility that allows isentropically creating multi-megabar pressure in easily compressed substances and studying their thermodynamic and kinetic properties is developed and successfully used nowadays. The mentioned substances are: rare gases and hydrogen isotopes, converted into condensed initial state. An ultra-high magnetic field MC-1 generator is used for ultra-high pressure obtaining on the device, and a cryostat of special design is used for cooling of the studied substance and its transition to a polycrystalline phase. In the paper we present a design and operating principle of the cryogenic device. By the example of deuterium it is shown how it is possible to describe the cooling and crystallization process. Calculation results and analysis of data of laboratory and field experiments show that at cooling it is possible to obtain the samples with the required sizes and initial temperature, and homogeneous enough in density.
开发了一种压缩装置,可以在易压缩的物质中等熵地产生数兆巴压力,并研究其热力学和动力学性质,目前已成功使用。上述物质是:稀有气体和氢的同位素,转化成凝聚的初始状态。该装置采用超高磁场MC-1发生器获得超高压,采用特殊设计的低温恒温器冷却所研究物质并使其向多晶态转变。本文介绍了一种低温装置的设计和工作原理。以氘为例,说明了如何能够描述冷却和结晶过程。室内和现场实验数据的计算结果和分析表明,在冷却时可以得到符合要求尺寸和初始温度的样品,并且密度足够均匀。
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引用次数: 2
Contribution of Vladimir K. Chernyshev to a Development of Explosive Pulsed Power and Applications 车尔尼雪夫对爆炸脉冲功率发展及其应用的贡献
A. V. Ivanovsky
V.K. Chernyshev proposed and realized (1958) a fast output of energy from the EMG circuit by means of its breaking by the HE charge and also by means of electric explosion. The current opening switches for the DEMG of POTOK family were developed under his leadership.V.K.Chernyshev together with his disciples created a small-size and power-intensive source of energy for a new type of powerful transportable sources of neutrons and together with other VNIIEF scientists they created a new pulsed system as a part of the complex.
车尔尼雪夫(V.K. Chernyshev)于1958年提出并实现了肌电图电路的快速输出,通过HE电荷和电爆炸的方式将其断开。目前POTOK家族DEMG的开路开关是在他的领导下开发的。v.k.chernyshev和他的门徒一起为新型强大的可传输中子源创造了一个小尺寸和能量密集型的能源,并与其他VNIIEF科学家一起创造了一个新的脉冲系统,作为该建筑群的一部分。
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引用次数: 0
2-D MHD Study of Instabilities During the Compression Phase of an Inverse Z-Pinch MTF System 逆z箍缩MTF系统压缩阶段不稳定性的二维MHD研究
P. V. Subhash, S. Madhavan, S. Chaturvedi
Two-dimensional MHD computations have been performed to study the growth of instabilities in an MTF system involving the cylindrical compression of a inverse Z-pinch target plasma by a metallic liner. The growth of modes in the plasma can be divided into two phases. During the first phase, the plasma continues to be Kadomtsev stable. The dominant mode in the liner instability is imposed upon the plasma in the form of a growing perturbation. This mode further transfers part of its energy to its harmonics. During the second phase, however, non-uniform implosion of the liner leads to axial variations in plasma quantities near the liner-plasma interface, such that certain regions of the plasma locally violate the Kadomtsev criteria. Further growth of the plasma modes is then due to plasma instability.
采用二维MHD计算方法研究了金属衬里对反z捏靶等离子体进行圆柱压缩的MTF系统中不稳定性的增长。等离子体中模式的生长可分为两个阶段。在第一阶段,等离子体继续保持卡多姆采夫稳定。线性不稳定性的主导模式以增长扰动的形式施加在等离子体上。这种模式进一步将部分能量转化为谐波。然而,在第二阶段,衬里的不均匀内爆导致衬里-等离子体界面附近等离子体数量的轴向变化,使得等离子体的某些区域局部违反Kadomtsev准则。等离子体模式的进一步增长是由于等离子体的不稳定性。
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引用次数: 0
Time Dependent Inductance Calculation of Magneto-Cumulative Generator During Explosion Using Finite Element Method 用有限元法计算累积磁发电机爆炸时电感
I. Sung, B. Joe, Chun-Yeol You, O. Kwon, Cheon Lee
The time dependent inductance variation is an essential ingredient in the design of magneto-cumulative generator. In most theoretical works, the inductance is modeled by a simple exponential form as a function of time. It is widely accepted that it is proper approximation for the time dependent inductance due to the constant expansion velocity of the liner during the explosion process. In this simple model, however, the magnetic field compression is not correctly treated. Since the inductance is related with the magnetic energy, which is determined by the magnetic flux density, the apposite consideration of the compression of the magnetic field is required. In order to include the effect of the compression of the magnetic field properly, we perform the finite element method calculation for the time dependent inductances in MCG during the explosion process. We find that the time dependent inductance can not be modeled with simple exponential model. Especially, the time derivative of the inductance shows more pronounces difference with the simple exponential model. In order to confirm the calculation results, we design mimic-explosion experiments in order to measure the inductances during the explosion process. It is revealed that the measurement data is well matched with the calculated one.
电感随时间的变化是累积磁发生器设计中的一个重要因素。在大多数理论著作中,电感是用简单的指数形式作为时间的函数来建模的。由于衬里在爆炸过程中膨胀速度恒定,因此人们普遍认为它是随时间变化的电感的适当近似。然而,在这个简单的模型中,没有正确地处理磁场压缩。由于电感与磁能有关,而磁能是由磁通密度决定的,因此需要适当地考虑磁场的压缩。为了适当地考虑磁场压缩的影响,我们对爆炸过程中MCG中随时间变化的电感进行了有限元计算。我们发现时间相关的电感不能用简单的指数模型来建模。特别是电感的时间导数与简单指数模型的差异更明显。为了验证计算结果,我们设计了模拟爆炸实验来测量爆炸过程中的电感。结果表明,实测数据与计算值吻合较好。
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引用次数: 0
Energy Compression Experiments: Simulation of Small-Size MCG to Obtain a Radio Frequency Source 能量压缩实验:模拟小尺寸MCG以获得射频源
M. M. Kekez
The electrically driven system was used to simulate the operation of sub-micro-size MCG. Initially, the maximum voltage at the output of the coil is les 6 kV, and the maximum current through the helical coil is < 4 kA. By compressing the energy stored in the coil, the electromagnetic induction voltage reaches up to 700 kV and the induced current is up to 10 kA. The goal of the work is to convert the available gigawatt power pulse into radio frequency (RF) radiations.
采用电驱动系统模拟了亚微尺寸MCG的运行过程。最初线圈输出端的最大电压小于6kv,通过螺旋线圈的最大电流小于4ka。通过压缩线圈中存储的能量,电磁感应电压可达700 kV,感应电流可达10 kA。这项工作的目标是将可用的千兆瓦功率脉冲转换为射频(RF)辐射。
{"title":"Energy Compression Experiments: Simulation of Small-Size MCG to Obtain a Radio Frequency Source","authors":"M. M. Kekez","doi":"10.1109/MEGAGUSS.2006.4530691","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530691","url":null,"abstract":"The electrically driven system was used to simulate the operation of sub-micro-size MCG. Initially, the maximum voltage at the output of the coil is les 6 kV, and the maximum current through the helical coil is < 4 kA. By compressing the energy stored in the coil, the electromagnetic induction voltage reaches up to 700 kV and the induced current is up to 10 kA. The goal of the work is to convert the available gigawatt power pulse into radio frequency (RF) radiations.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125664077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Single Turn Multi-Megagauss System at the NHMFL-LOS Alamos to study plutonium NHMFL-LOS Alamos的单转多兆高斯系统来研究钚
C. Mielke, R. McDonald
By utilizing a fast capacitor bank and the single-turn coil technique, a new megagauss system has been commissioned at Los Alamos National Laboratory. The system is specially designed for condensed matter physics experimentation on metallic plutonium and other actinides in extremely high magnetic fields. In addition to special conditions required for handling hazardous samples, the system features 24 synchronous switches at a maximum voltage of 60 kV and a maximum current approaching 4 MA. Peak magnetic fields approaching 300 tesla are predicted for the system. System design and issues related to condensed matter physics experimentation are discussed.
通过利用快速电容器组和单匝线圈技术,一个新的兆高斯系统已经在洛斯阿拉莫斯国家实验室投入使用。该系统是专门为在极高磁场下对金属钚和其他锕系元素进行凝聚态物理实验而设计的。除了处理危险样品所需的特殊条件外,该系统还具有24个同步开关,最大电压为60 kV,最大电流接近4 MA。预计该系统的峰值磁场接近300特斯拉。讨论了凝聚态物理实验的系统设计及相关问题。
{"title":"Single Turn Multi-Megagauss System at the NHMFL-LOS Alamos to study plutonium","authors":"C. Mielke, R. McDonald","doi":"10.1109/MEGAGUSS.2006.4530682","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530682","url":null,"abstract":"By utilizing a fast capacitor bank and the single-turn coil technique, a new megagauss system has been commissioned at Los Alamos National Laboratory. The system is specially designed for condensed matter physics experimentation on metallic plutonium and other actinides in extremely high magnetic fields. In addition to special conditions required for handling hazardous samples, the system features 24 synchronous switches at a maximum voltage of 60 kV and a maximum current approaching 4 MA. Peak magnetic fields approaching 300 tesla are predicted for the system. System design and issues related to condensed matter physics experimentation are discussed.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"175 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126944412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 7
期刊
2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics
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