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

{"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}

{"title":"Using Magneto-Hydrodynamic and High Magnetic Field Experiments to Validate Modern Multi-Physics Codes that Simulate Extreme Conditions","authors":"R. Reinovsky, C. Rousculp","doi":"10.1109/MEGAGAUSS.2018.8722664","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722664","url":null,"abstract":"Understanding the interaction of high magnetic fields with metal conductors, especially in dynamic situations where parts of the conductor may ohmically heat, change state, move, undergo complex hydro-dynamic behavior, ionize, or produce surface vapor or plasma has been one traditional emphasis for the Megagauss community. A moving (imploding) cylindrical liner used for flux compression, plasma compression, and constitutive properties or shock physics experiments is one application where this detailed understanding of fields and materials is important. Cylindrical liner compression experiments, enabled by pulsed power technology and the resulting “megagauss” fields can challenge the models in modern multi-physics codes, and the validation of these models within their related code framework becomes an important application for the technology developed by the Megagauss community.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"129 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":"116033920","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}

{"title":"Effect of Electrodes Erosion on Electromagnetic Energy Transport Along Vacuum Transmission Lines","authors":"Nikolay V.Egorov, Y. Kudasov, P. B. Repin","doi":"10.1109/MEGAGAUSS.2018.8722675","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722675","url":null,"abstract":"The calculation model of the current erosion of the steel considering its inhomogeneous microstructure is described. A two-dimensional magneto-hydrodynamic simulation of the effect of the erosion products of the microstructural electrodes on the electromagnetic energy transport along the section of a vacuum radial transmission line is carried out. It is shown that a large part of the evaporated substance of the electrodes is penetrated into the interelectrode gap of the line. It leads to a closing of an interelectrode gap. The transmission line electrodes without a microstructure are not affected by the current erosion in the same conditions; their heating is observed only up to ~500 K.","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":"129505278","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}

{"title":"Map","authors":"","doi":"10.1109/megagauss.2018.8722666","DOIUrl":"https://doi.org/10.1109/megagauss.2018.8722666","url":null,"abstract":"","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"29 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":"123402962","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}

{"title":"Applications of Helical Magneto-Cumulative Generators in Physical Experiments","authors":"V. A. Demidov","doi":"10.1109/megagauss.2018.8722681","DOIUrl":"https://doi.org/10.1109/megagauss.2018.8722681","url":null,"abstract":"Magneto-cumulative generators (MCGs) are powerful high-energy sources of energy. Helical generators (HMCGs) are the most universal generators among different types of MCGs. They can form powerful current pulses (up to tens of megaamperes) in the loads with different parameters having a high initial inductance and high rate of its change. Modern high-inductive and high-speed HMCGs can amplify the initial energy tenfold and hundredfold providing the output magnetic energy up to 20–30 MJ and power of several hundreds of gigawatts. A short review of different applications of HMCGs both in VNIIEF and in other world laboratories is provided in the report.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"3 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":"133631997","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}

{"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}

{"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}

{"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}

{"title":"Copyright","authors":"","doi":"10.1109/megagauss.2018.8722686","DOIUrl":"https://doi.org/10.1109/megagauss.2018.8722686","url":null,"abstract":"","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"59 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":"121686534","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}

{"title":"25th Anniversary of the Joint US-Russian Disk EMG Experiment","authors":"A. Buyko, R. Reinovsky, S. Garanin, I. Lindemuth","doi":"10.1109/MEGAGAUSS.2018.8722651","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722651","url":null,"abstract":"Twenty-five years ago, on September 22, 1993, an event, unprecedented in the nuclear age, took place at Arzamas-16, Russia, as the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) and the Los Alamos National Laboratory (LANL), the two institutes that designed the first nuclear weapons of their respective nations, combined capabilities to conduct a joint scientific experiment. The experiment used a VNIIEF disk explosive magnetic flux compression generator (EMG) with an electrically exploded foil opening switch (FOS) to transfer multi-megajoule pulse of electric energy on a microsecond timescale to a magnetic implosion assembly. Despite a breakdown in the transmission line, the experiment delivered a load current of 20 MA, then-unattainable in stationary laboratory-scale experiments, and drove an electrically exploded liner to a velocity of 25 km/s. The experiment demonstrated the applications of the EMG-based pulsed power system to high energy density research, and resulted in the subsequent expansion through the 1990s and into the 2000s of joint VNIIEF/LANL EMG-enabled work on imploded liners and their applications. The success of the joint efforts led to new projects in plasma physics and fusion research, materials science, and driver technology development; and set the stage for additional programs in material control and accountability and several other high level international agreements on cooperation. The collaboration between VNIIEF and LANL demonstrated that joint efforts can deliver results not heretofore attainable through the efforts of any one institution. The results of this work constitute important milestones in physics and engineering development and are widely used today. These results include but are not limited to the following: •Magnetized hot plasma studies as applied to fusion ignition in MAGO-MTF systems; •Record-setting liner energy in the HEL-1 experiment (the 25-MJ record of this experiment has not been beaten yet) making the liner suitable for plasma compression in the MAGO-MTF system; •Use of disk EMGs with FOS to drive condensed-matter liners and to study materials properties (ALT-1, 2, RHSR-1, 2 experiments).","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"7 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":"125678029","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}