2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)最新文献

Magnetoelastics of High Field Phenomena in Antiferromagnets UO2 and CeRhIn5 反铁磁体UO2和CeRhIn5中高场现象的磁弹性

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/MEGAGAUSS.2018.8722665

M. Jaime, K. Gofryk, E. Bauer

{"title":"Magnetoelastics of High Field Phenomena in Antiferromagnets UO2 and CeRhIn5","authors":"M. Jaime, K. Gofryk, E. Bauer","doi":"10.1109/MEGAGAUSS.2018.8722665","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722665","url":null,"abstract":"We use a recently developed optical fiber Bragg grating technique, in continuous and pulsed magnetic fields in excess of 90T, to study magnetoelastic correlations in magnetic materials at cryogenic temperatures. Both insulating UO2 and metallic CeRhIn5 present antiferromagnetic ground states, at $mathrm{T}_{N}= 30.3mathrm{K}$ and $mathrm{T}_{N}= 3.85mathrm{K}$ respectively. Strong coupling of the magnetism to the crystal lattice degrees of freedom in UO2 is found, revealing piezomagnetism as well as the dynamics of antiferromagnetic domain switching between spin arrangements connected by time reversal. The AFM domains become harder to switch as the temperature is reduced, reaching a record value $mathrm{H}_{pz} (mathrm{T} = 4mathrm{K}) sim 18mathrm{T}$. The effect of strong magnetic fields is also studied in CeRhIn5, where an anomaly in the sample crystallographic c-axis of magnitude Δc/c ≃ 2 ppm is found associated to a recently proposed electronic nematic state at $mathrm{H}_{en} sim 30mathrm{T}$ applied 11° off the c-axis. Here we show that while this anomaly is absent when the magnetic field is applied 18° off the a-axis, strong magnetoelastic quantum oscillations attest to the high quality of the single crystal samples.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126743033","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

Using Magneto-Hydrodynamic and High Magnetic Field Experiments to Validate Modern Multi-Physics Codes that Simulate Extreme Conditions 利用磁流体力学和强磁场实验验证模拟极端条件的现代多物理场代码

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/MEGAGAUSS.2018.8722664

R. Reinovsky, C. Rousculp

引用次数: 0

Effect of Electrodes Erosion on Electromagnetic Energy Transport Along Vacuum Transmission Lines 电极腐蚀对真空输电线路电磁能量输运的影响

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/MEGAGAUSS.2018.8722675

Nikolay V.Egorov, Y. Kudasov, P. B. Repin

引用次数: 0

Map 地图

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/megagauss.2018.8722666

引用次数: 0

Applications of Helical Magneto-Cumulative Generators in Physical Experiments 螺旋磁累积发生器在物理实验中的应用

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/megagauss.2018.8722681

V. A. Demidov

引用次数: 0

Simulation of Isentropic Compression of Aluminum by Magnetically Imploded Liners in experiments ALT-1-3 实验中磁内爆衬垫对铝等熵压缩的模拟

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/MEGAGAUSS.2018.8722649

S. Kuznetsov, A. Buyko, S. Garanin, M. A. Desyatnikova, G. G. Ivanova, V. Karepov, V. B. Yakubov

{"title":"Simulation of Isentropic Compression of Aluminum by Magnetically Imploded Liners in experiments ALT-1-3","authors":"S. Kuznetsov, A. Buyko, S. Garanin, M. A. Desyatnikova, G. G. Ivanova, V. Karepov, V. B. Yakubov","doi":"10.1109/MEGAGAUSS.2018.8722649","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722649","url":null,"abstract":"High precision measurements of accelerated liner velocities (by optical velocimetry VISAR, PDV) produce high-resolution isentropes of test materials - pressure-density curves in the whole range of pressures reached in a single shot [1]. Their interpretation requires solving an inverse mathematical problem by Iterative Lagrangian Analysis (ILA) methods. But in case of magnetic implosion of liners, when the highest isentropic pressures are generated by cumulation, application of such methods presents difficulties. In this paper, we use a similar method of inverse solution with optimization: a small number of parameters are varied to reach the best match between the experimental velocity of the inner liner boundary and the velocity obtained by 1D magnetohydrodynamic calculations. As an example we consider the implosion of aluminum liners having a radius of 4cm and thickness of 2-3mm driven by currents up to 30-75MA (azimuthal magnetic field up to 2-10MG) delivered by ALT-1-3 devices [2]–[3], when liner velocities and isentropic pressures in aluminum reach 12-40km/s and 0.2-8Mbar. Inner liner surface velocities measured by VISAR in the ALT-1,2 experiments reached 12 km/s. The resulting isentrope of aluminum is close to the experimental data available. Accuracy specifications for liner velocity measurements up to 40 km/s in the developed ALT-3 driver were discussed.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127389269","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: 0

Prospects for development of pulsed source with a yield 1014 DT-neutrons based on spherical DPF chamber 基于球形DPF腔的1014dt中子产率脉冲源的发展展望

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/megagauss.2018.8722685

V. Dolinskii, D. A. Ershov, A. P. Falin, S. F. Garanin, A. V. Garin, O. N. Petrushin, Yu. S. Shigaev

{"title":"Prospects for development of pulsed source with a yield 1014 DT-neutrons based on spherical DPF chamber","authors":"V. Dolinskii, D. A. Ershov, A. P. Falin, S. F. Garanin, A. V. Garin, O. N. Petrushin, Yu. S. Shigaev","doi":"10.1109/megagauss.2018.8722685","DOIUrl":"https://doi.org/10.1109/megagauss.2018.8722685","url":null,"abstract":"Presented are study results, aimed at development of a high-intense neutron source based on a spherical gas-discharge chamber with a dense plasma focus (DPF). At present, as a result of studies of physical processes, specifying plasma formations dynamics in spherical DPF chambers, VNIIEF has developed a neutron radiation source facility with half-height pulse duration 75–80 ns and integral yield 1013 DT-neutrons [1]. When using information, obtained during experiments on the developed source, a capability for acquiring a yield of 1014 DT-neutrons is studied when raising the stored energy up to 350 kJ and the current amplitude up to 2.4 MA. To approach the mentioned parameters one should enhance the capacitance of capacitor bank up to 600 µF and the chamber anode diameter up to 200 mm. Conducted MHD calculations with above-indicated parameters prove the possibility for neutron yield increase. The neutron yield is calculated taking into account accelerative mechanism of neutron generation described in paper [2].","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125505535","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: 1

A Small D-dot for Use on Flux Compression Generators 用于通量压缩发生器的小d点

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/MEGAGAUSS.2018.8722670

R. Richardson, A. Johnson, A. D. White, A. Young, J. Trueblood, J. B. Javidani, D. P. Milhous, T. Ferriera

{"title":"A Small D-dot for Use on Flux Compression Generators","authors":"R. Richardson, A. Johnson, A. D. White, A. Young, J. Trueblood, J. B. Javidani, D. P. Milhous, T. Ferriera","doi":"10.1109/MEGAGAUSS.2018.8722670","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722670","url":null,"abstract":"A D-dot voltage probe was designed and tested on a megajoule class flux compression generator (FCG) to measure the voltage on the generator load. Design calculations will be shown, along with experimental data taken from laboratory prototype testing as well as the explosive FCG experiment. The D-dot was terminated in a high impedance amplifier, so that the D-dot is mostly self-integrating (i.e. a capacitive divider). The amplifier limits the bandwidth of the probe to 40 MHz, which was sufficient for the transients expected in the experiment. The high sensitivity of this termination allows the use of a small, non-disturbing probe. The FCG D-dot data, combined with a measurement of the current using B-dot probes, can be used to calculate the dynamic impedance of the load. The load for the FCG was designed to be a static inductor, however, small load impedance changes on the order of 10's of μOhm are present as the conductors heat up and move apart at high current. This change in impedance of the load was modeled with ALE3D (multi-physics Lawrence Livermore code) [1] and compared to the measured voltage.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"42 S1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120977813","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: 1

Copyright 版权

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/megagauss.2018.8722686

引用次数: 0

On the Results of an Experiment with a Megajoule Class Helical Flux Compression Generator Operating at Above Nominal Levels of Current and Voltage Stress 在高于额定电流和电压应力水平下工作的兆焦耳级螺旋磁通压缩发生器的实验结果

2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS) Pub Date : 2018-09-01 DOI: 10.1109/MEGAGAUSS.2018.8722652

A. Young, A. D. White, J. Trueblood, A. Lodes, H. Loey, R. Richardson, A. Johnson, D. P. Milhous, A. Ferriera, R. Speer, E. Baluyot, A. Bockman, R. K. Hicks, K. Hood, J. Javedani, S. Leahy, T.T. Leever, G. Mease, D. Norton, A. Pearson, A. Ray, M. Tillman, D. Herrera, P. Dickson, J. Gunderson

{"title":"On the Results of an Experiment with a Megajoule Class Helical Flux Compression Generator Operating at Above Nominal Levels of Current and Voltage Stress","authors":"A. Young, A. D. White, J. Trueblood, A. Lodes, H. Loey, R. Richardson, A. Johnson, D. P. Milhous, A. Ferriera, R. Speer, E. Baluyot, A. Bockman, R. K. Hicks, K. Hood, J. Javedani, S. Leahy, T.T. Leever, G. Mease, D. Norton, A. Pearson, A. Ray, M. Tillman, D. Herrera, P. Dickson, J. Gunderson","doi":"10.1109/MEGAGAUSS.2018.8722652","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722652","url":null,"abstract":"An experiment conducted with a megajoule class helical flux compression generator (HFCG), operating into a primarily inductive load, is described. The motivation behind the experiment was to benchmark the performance of the generator at higher currents and voltages than were tested in prior experiments. The intention was to push operation into a regime where flux loss was likely to become nonlinear, thereby gaining some insight into performance limitations of the design. Another goal was the desire to benchmark the suite of computational tools used to predict the performance of the design, especially in regimes of nonlinear flux loss. In the experiment, the HFCG was seeded with 105 kA (1.05 Wb), and produced 8.6 MA (0.28 Wb) into the load. This result differed significantly from computational models of the experiment, which predicted greater than 10 MA into the load. While more than one source of flux loss was observed in the waveforms, the dominant source of loss appears to be associated with joule heating and magnetic diffusion, which were found to have the most impact during the latter stages of HFCG operation. Details of the experiment design, setup and execution will be given. Analysis of the captured data, along with comparison of these data with model predictions and past experimental data, will be shown.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114359610","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: 3