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

{"title":"Interaction the high-density pulse current with material in the zone of local conduction disturbance at the edge of a thin wall magnetic system","authors":"Yuri E. Adamyan, D. Alekseev, L. Chernenkaya, S. Krivosheev, S. Magazinov, V. Titkov","doi":"10.1109/MEGAGAUSS.2018.8722688","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722688","url":null,"abstract":"The results of numerical simulation and experimental study of a defect formation on the edge of flat busbars during impulse current application are introduced. It is shown that the growth of defects can be described with the use of the magnetohydrodynamic approach, typically applied for describing the destruction of solenoids in strong pulsed magnetic fields.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"103 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":"116982135","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":"Megagauss 16: Summary of pulsed power","authors":"","doi":"10.1109/megagauss.2018.8722662","DOIUrl":"https://doi.org/10.1109/megagauss.2018.8722662","url":null,"abstract":"","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"51 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":"121561461","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":"Cylindrical Driven Shocks in Ceria","authors":"M. Freeman, C. Rousculp, D. Fredenburg, J. Bradley, P. M. Donovan, J. Dunwoody, F. Fierro, J. Griego, J. C. Lamar, F. Mariam, L. Neukirch, D. Oró, A. Patten, R. Randolph, W. Reass, R. Reinovsky, A. Saunders, S. Sjue, Z. Tang, P. Turchi, T. Voorhees","doi":"10.1109/MEGAGAUSS.2018.8722648","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722648","url":null,"abstract":"Shock compression of granular ceria (CeO2) was studied in converging cylindrical geometry using LANL proton radiography, and driven by the Precision High Energy-Density Liner Implosion Experiment (PHELIX) magnetic implosion system. PHELIX delivered nearly 4 MA to a 1.25-mm thick liner-impactor to magnetically accelerate it to ~0.8-1.0 mm μs−1. The impactor launched a shock in the cylindrical Al outer wall of the target assembly containing equiaxed, 0.63-μm-mean diameter ceria powder initially compacted to a static density of 3.95 or 4.03 g cm−3. The cylindrically converging shock in the target was observed with a series of 21 proton-radiographic frames down the axis of the cylinder. Proton radiography was performed using a ×3 magnetic lens magnifier and a 7.5-mrad collimator. The proton radiographic views were transformed from transmission images to areal density images, for comparison to a model. Results indicate that significant energy was expended in compacting the porous CeO2, as the wave velocity markedly decreases during convergence, and a clear shock reflected from the axis was not observed. These observations are inconsistent with pre-shot modeling, and highlight the need for an improved understanding of the physics of compaction under non-ideal loading configurations.","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":"126546427","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":"On acceleration of shells by explosive magnetic generators and cascade systems","authors":"B. E. Grinevich, A. V. Ivanovsky, K. N. Klimushkin, V. Mamyshev, N. Sitnikova, E. V. Shapovalov","doi":"10.1109/megagauss.2018.8722680","DOIUrl":"https://doi.org/10.1109/megagauss.2018.8722680","url":null,"abstract":"The application of disk explosive magnetic generators (DEMG) to drive cylindrical condensed liners makes it possible to impart to them the velocities higher than those achieved at direct acceleration of the liners by the products of explosion of condensed explosives (HE). One of the ways to increase further the velocities of the liners is to construct the cascade systems. The results of calculations of the conditions required for a magnetic drive of massive liners to velocities 20–50 km/s are presented.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"38 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":"126097903","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":"Magnetostriction studies up to megagauss fields using fiber Bragg grating technique","authors":"A. Ikeda, Y. Matsuda, D. Nakamura, S. Takeyama, H. Tsuda, K. Nomura, Ayumi Shimizu, A. Matsuo, T. Nomura, Tatsuo C. Kobayashi, T. Yajima, H. Ishikawa, Z. Hiroi, M. Isobe, T. Yamauchi, Keisuke Sato","doi":"10.1109/MEGAGAUSS.2018.8722656","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722656","url":null,"abstract":"We here report magnetostriction measurements under pulsed megagauss fields using a high-speed 100 MHz strain monitoring system devised using fiber Bragg grating (FBG) technique with optical filter method. The optical filter method is a detection scheme of the strain of FBG, where the changing Bragg wavelength of the FBG reflection is converted to the intensity of reflected light to enable the 100 MHz measurement. In order to show the usefulness and reliability of the method, we report the measurements for solid oxygen, spin-controlled crystal, and volborthite, a deformed Kagomé quantum spin lattice, using static magnetic fields up to 7 T and non-destructive millisecond pulse magnets up to 50 T. Then, we show the application of the method for the magnetostriction measurements of CaV4O9, a two-dimensional antiferromagnet with spin-halves, and LaCoO3, an anomalous spin-crossover oxide, in the megagauss fields.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"20 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":"131019002","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":"Capabilities of Explosive Magnetic Generators for Precision Research of Equations-of-State at Isentropic Compression","authors":"E. V. Shapovalov, A. Ivanovskiy, A. A. Bazanov, V. K. Baranov, A. Buyko, P. Duday, A. Golubinsky, S. F. Garanin, V. Karepov, S. Kuznetsov, V. Mamyshev","doi":"10.1109/MEGAGAUSS.2018.8722687","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722687","url":null,"abstract":"The method to study the isentropic compressibility of substances is presented in [1]. A two-layered liner made of an explored material specimen and of an outer current-carrying aluminum tube is driven by the current of Z-machine. Another aluminum liner serves as an anode. The measurements of velocity of the specimen' inner surface and of the anode' outer surface are necessary in the iterative method. In combination with magnetohydrodynamic modeling and mathematical optimization this allows obtaining current, pressure and density in the specimen. Copper was compressed by the pressure of ~ 1000 GPa. The accuracy of pressure determination is 5.7% and of density determination is 1.8%. The capabilities of the disk explosive magnetic generators to conduct similar research are analyzed.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"23 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":"115783522","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":"Magnetic Field Flow Around a Screen with a Slot","authors":"S. Garanin, S. Kuznetsov, K. Vlasov","doi":"10.1109/MEGAGAUSS.2018.8722660","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722660","url":null,"abstract":"Current-free magnetic field configurations in the planar case are described by the Laplace equation for the potential or for the flux function. Then, the problem can be defined both as a hydrodynamic one for a potential incompressible fluid flow and as an electrostatic one for an electric field potential. In the problem of a magnetic field flow around an ideally conducting screen with a slot the screen is divided into two conductors and the no-full-current condition for both of them results in a considerable magnetic flux (of the order of $c_{1}B_{0}D/1 (frac{c_{2}D}{Delta}))$ passing through a narrow slot of width $Delta$, where $B_{0}$ is the magnetic field at infinity, $D$ is the screen width, and $c_{1}$ and $c_{2}$ are dimensionless constants on the order of unity. This means that the average magnetic field in the slot will grow with decrease in $Delta$ and, in a sufficiently narrow slot, can by far exceed $B_{0}$ that can be used for magnetic field concentration in various devices. The constants $c_{1}$ and $c_{2}$ are approximately equal to $c_{1}=1.57, c_{2}=3.9$, so the slot-average magnetic field for a slot of width $Delta=0.01D$ will be 26Bo. The results also hold true for the hydrodynamic problem of a potential incompressible fluid flow around a screen with a slot. Instead of the magnetic field, there will be a velocity, and instead of the magnetic flux, a fluid flux with an average velocity concentrated in the slot according to the same law. The hydrodynamic problem of a flow around a screen with a slot can also be given in an axially symmetric setup, in the $pmb{r}$ and $z$ coordinates, when the screen is a round plate with an orifice. In this case, if the orifice is small enough, the fluid flux will be proportional to the orifice diameter $Delta$, and the velocity of the flow through the orifice will grow as $1/Delta$ with decrease in $Delta$, i.e. somewhat faster than in the planar case.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"12 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":"115095414","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":"Celebration of Max Fowler's Birthday","authors":"J. H. Goforth","doi":"10.1109/MEGAGAUSS.2018.8722654","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722654","url":null,"abstract":"At the MG-XV conference in Portugal 2016, the International Steering Committee made the decision to hold the MG-XVI conference in Japan in 2018 to include a celebration of the 100th birthday of Max Fowler. Max gave the first paper of the first Megagauss conference in 1965, and became a central figure when the conference became a recurring series of meetings in 1979. Max attended every conference until he passed away in 2006, and his wife, Janet, also became a conference essential. This paper recounts the talk given from the American perspective during the celebration, and a paper by Gennady Shvetsov recounts the celebration from the Russian perspective.","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":"125538308","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":"The Path to 100 MJ Ranchero Experiments","authors":"J. H. Goforth, R. Watt","doi":"10.1109/MEGAGAUSS.2018.8722653","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722653","url":null,"abstract":"Ranchero is the name given to a class of Los Alamos coaxial flux compression generators (FCGs) that are detonated simultaneously along the cylindrical axis. An experiment was reported at MG-XIV in which a Ranchero FCG produced 76 MA peak current, and in MG-XV a design was presented which was intended to overcome a weakness uncovered in the 76 MA test. The name used for the new Ranchero configuration is “Ranchero-S”, and that improvement has now been successfully tested. The results of the test are presented in detail in another paper in this conference. This paper reports on scaling studies that are benchmarked by recent experiments, and which demonstrate the approach that would be taken to extend the Ranchero-S performance to levels of 100 MJ and 1.5 Weber. The primary scaling parameter for achieving larger currents is increasing the circumference of the FCG. Detonation systems are available in lengths of 0.43 m, 0.72 m, 1.0 m, and 1.44 m. The longer FCGs can operate with lower initial current for any given peak current and load, which allows them to be less effected by early time back pressure. However, at very high initial current, the effect of having a substantial field operating on a long armature over a substantial time can be seen. As diameter is increased, the flux compression time is increased if the initial inductance is held constant. The flux compression time can be held constant as radius is increased by keeping the armature to stator gap constant, with the result that the ideal gain is reduced for a given module length. The various possibilities are presented, with an emphasis on operating at current levels that approach the limits imposed by armature kinetic energy versus magnetic pressure. Another key feature in performing 100 MJ experiments is the existence of a booster generator which can produce seed currents well in excess of the three to four MA that can be delivered by the 2.4 MJ capacitor bank available at the Los Alamos explosive pulsed power firing facility. The MK-IX generator, which has been used in many experiments previously reported, has potential for producing the necessary seed current. However, a new booster FCG is being developed for that purpose, which will employ modern machining techniques to replace labor intensive methods required by the MK-IX fabrication. This FCG is called the MK-X, and the first test of this device is imminent. Either the MK-IX or the new MK-X booster will need further experimentation to demonstrate the capacity for delivering the approximately 2.5 Weber flux to a Ranchero FCG that projections in this paper require for the full 100 MJ, 1.5 Weber performance.","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":"121061654","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":"Generation of 0.5 to 0.6 Mega Gauss Pulse Magnetic Field for Magnetic Pulse Welding of High Strength Alloys","authors":"Surender Kumar Sharma, Aravind Jmmvs, S. Mishra, Renu Rani, Sukant Mishra, N. Waghmare, Archana Sharma","doi":"10.1109/MEGAGAUSS.2018.8722676","DOIUrl":"https://doi.org/10.1109/MEGAGAUSS.2018.8722676","url":null,"abstract":"Magnetic Pulse Welding (MPW) is a solid state welding process to join high strength alloys and dissimilar materials. In this technique, the joining is realized by the impact of job pieces at 150 m/s to 1500 m/s caused by an action of pulse magnetic field. The pulse magnetic field of > 50 T is generated inside the welding coil by the discharge of 40 kJ capacitor bank. Pulse discharge current of 132 kA and 112 kA is pumped in five turn disk coil and five turn disk coil with field shaper, which produces a magnetic field of 60 T and 50 T in 10 mm bore diameter of respective coils. This magnetic field exerts a pressure on the tubular job piece and accelerates it to impact at high velocity and obtains a weld. The inner region of the coils got deformed during welding of job pieces due to the high stress in the inner region. The construction details of multi turn disk coil and multi turn disk coil with field shaper for pulsed magnetic field generation and welding of SS316L tube of 0.5 mm thickness and 6.5 mm diameter to SS316L rod is presented in the paper.","PeriodicalId":207949,"journal":{"name":"2018 16th International Conference on Megagauss Magnetic Field Generation and Related Topics (MEGAGAUSS)","volume":"36 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":"129129748","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}