Pub Date : 2006-11-01DOI: 10.1109/MEGAGUSS.2006.4530710
D. Tasker, J. Goforth, H. Oona
One-dimensional isentropic compression experiments (ICE) have been performed over the last few years at the Los Alamos National Laboratory (LANL) using a High Explosive Pulsed Power (HEPP) system. Accurate, high pressure, isentropic Equations of State (EOS) data have been obtained for copper and tungsten. A number of important issues have been identified, such as: magnetic field (B-field) uniformity; sample-to-sample B-field uniformity; sample size constraints; the maximum stress before shock-up; and accuracy. The results for tungsten show non-ideal elastic to plastic transition features, but an experimental isentrope that is close to theoretical values.
{"title":"Summary of Isentropic Compression Experimentsperformed with High Explosive Pulsed Power","authors":"D. Tasker, J. Goforth, H. Oona","doi":"10.1109/MEGAGUSS.2006.4530710","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530710","url":null,"abstract":"One-dimensional isentropic compression experiments (ICE) have been performed over the last few years at the Los Alamos National Laboratory (LANL) using a High Explosive Pulsed Power (HEPP) system. Accurate, high pressure, isentropic Equations of State (EOS) data have been obtained for copper and tungsten. A number of important issues have been identified, such as: magnetic field (B-field) uniformity; sample-to-sample B-field uniformity; sample size constraints; the maximum stress before shock-up; and accuracy. The results for tungsten show non-ideal elastic to plastic transition features, but an experimental isentrope that is close to theoretical values.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"36 4 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":"124992563","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}
Pub Date : 2006-11-01DOI: 10.1109/MEGAGUSS.2006.4530671
R. Faehl, I. Lindemuth, R. Siemon, T. Awe
We present an analytic treatment of the transport of magnetic field into a metallic material, when the surface field is changing in time. This has many applications in the area of high-current pulsed power. We focus on one of these in this paper, magnetized target fusion (MTF), a simple, potentially inexpensive method of creating burning fusion conditions through fast compression of dense, warm magnetized plasma. Magnetization of the plasma electrons, needed to inhibit thermal transport losses, means that compression, on the order of 10 microseconds (10-5 seconds), results in large magnetic field compression. Current density, J, proportional to the field gradient in the walls, is also found analytically. Heating in the wall is also a function of etaJ2, and so can also be evaluated with these solutions. MTF studies proposed to be conducted at the ATLAS pulsed-power facility (23 MJ, 30 MA, 240 kV), must explicitly determine energy dissipation in the wall. Vaporization, or possibly even melting, of metallic wall material could lead to mixing of such high-Z material with the hot hydrogen plasma. The ensuing radiation losses and plasma cooling would be catastrophic to any MTF scheme.
{"title":"Wall Heating and Impurity Mixing Considerations During Magnetic Compression Experiments","authors":"R. Faehl, I. Lindemuth, R. Siemon, T. Awe","doi":"10.1109/MEGAGUSS.2006.4530671","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530671","url":null,"abstract":"We present an analytic treatment of the transport of magnetic field into a metallic material, when the surface field is changing in time. This has many applications in the area of high-current pulsed power. We focus on one of these in this paper, magnetized target fusion (MTF), a simple, potentially inexpensive method of creating burning fusion conditions through fast compression of dense, warm magnetized plasma. Magnetization of the plasma electrons, needed to inhibit thermal transport losses, means that compression, on the order of 10 microseconds (10-5 seconds), results in large magnetic field compression. Current density, J, proportional to the field gradient in the walls, is also found analytically. Heating in the wall is also a function of etaJ2, and so can also be evaluated with these solutions. MTF studies proposed to be conducted at the ATLAS pulsed-power facility (23 MJ, 30 MA, 240 kV), must explicitly determine energy dissipation in the wall. Vaporization, or possibly even melting, of metallic wall material could lead to mixing of such high-Z material with the hot hydrogen plasma. The ensuing radiation losses and plasma cooling would be catastrophic to any MTF scheme.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"4 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":"127019230","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}
Pub Date : 2006-10-31DOI: 10.1109/MEGAGUSS.2006.4530665
J. Degnan, A. Brown, Tereza Cavazos, S. Coffey, M. Domonkos, M. Frese, S. Frese, D. Gale, C. Gilman, C. Grabowski, T. Intrator, R. Kirkpatrick, G. Kiuttu, F. Lehr, J. Parker, R. Peterkin, N. Roderick, E. Ruden, R. Siemon, W. Sommars, W. Tucker, P. Turchi, G. Wurden, Y. Thio
Magnetized Target Fusion (MTF) is a means to compress plasmas to fusion conditions that uses magnetic fields to greatly reduce electron thermal conduction, thereby greatly reducing compression power density requirements (1,2). The compression is achieved by imploding the boundary, a metal shell. This effort pursues formation of the Field Reversed Configuration (FRC) type of magnetized plasma, and implosion of the metal shell by means of magnetic pressure from a high current flowing through the shell. We reported at Megagauss 9 that we had shown experimentally (3) that we can use magnetic pressure from high current capacitor discharges to implode long cylindrical metal shells (liners) with size, symmetry, implosion velocity, and overall performance that is suitable for compression of Field Reversed Configurations (FRC's). We also presented considerations of using deformable liner ¿ electrode contacts of Z-pinch geometry liners or theta pinch driven liners, in order to have axial access to inject FRC's and to have axial diagnostic access. Since then, we have experimentally implemented the Z-pinch discharge driven deformable liner ¿ electrode contact, obtained full axial coverage radiography of such a liner implosion, and obtained 2D-MHD simulations for a variety of profiled thickness long cylindrical liners. The radiographic results indicate that at least 16 times radial compression of the inner surface of a 0.11 cm thick Al liner was achieved, with a symmetric implosion free of instability growth. We have also made progress in combining 2D-MHD simulations of FRC formation with imploding liner compression of FRC's.
磁化靶聚变(Magnetized Target Fusion, MTF)是一种利用磁场将等离子体压缩到聚变条件的方法，这种方法大大降低了电子热传导，从而大大降低了压缩功率密度要求(1,2)。压缩是通过内爆边界，即金属外壳来实现的。这一努力追求磁场反向配置(FRC)型磁化等离子体的形成，以及通过流经外壳的高电流产生的磁压力使金属外壳发生内爆。我们在Megagauss 9报告说，我们已经通过实验(3)表明，我们可以使用大电流电容器放电产生的磁压力内爆长圆柱形金属壳(衬里)，其尺寸、对称性、内爆速度和整体性能都适合于压缩场反转结构(FRC)。我们还提出了使用可变形衬垫- z -捏几何衬垫或θ -捏驱动衬垫的电极触点的考虑，以便有轴向通道注入FRC并有轴向诊断通道。从那时起，我们通过实验实现了Z-pinch放电驱动的可变形衬垫电极接触，获得了这种衬垫内爆的全轴向覆盖射线照相，并获得了各种异形厚度长圆柱形衬垫的2D-MHD模拟。射线照相结果表明，0.11 cm厚铝衬垫的内表面发生了至少16倍的径向压缩，并伴有对称内爆，无不稳定生长。我们还在将FRC地层的2D-MHD模拟与FRC的内爆尾管压缩相结合方面取得了进展。
{"title":"Progress on Liner Implosions for Compression of FRC's","authors":"J. Degnan, A. Brown, Tereza Cavazos, S. Coffey, M. Domonkos, M. Frese, S. Frese, D. Gale, C. Gilman, C. Grabowski, T. Intrator, R. Kirkpatrick, G. Kiuttu, F. Lehr, J. Parker, R. Peterkin, N. Roderick, E. Ruden, R. Siemon, W. Sommars, W. Tucker, P. Turchi, G. Wurden, Y. Thio","doi":"10.1109/MEGAGUSS.2006.4530665","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530665","url":null,"abstract":"Magnetized Target Fusion (MTF) is a means to compress plasmas to fusion conditions that uses magnetic fields to greatly reduce electron thermal conduction, thereby greatly reducing compression power density requirements (1,2). The compression is achieved by imploding the boundary, a metal shell. This effort pursues formation of the Field Reversed Configuration (FRC) type of magnetized plasma, and implosion of the metal shell by means of magnetic pressure from a high current flowing through the shell. We reported at Megagauss 9 that we had shown experimentally (3) that we can use magnetic pressure from high current capacitor discharges to implode long cylindrical metal shells (liners) with size, symmetry, implosion velocity, and overall performance that is suitable for compression of Field Reversed Configurations (FRC's). We also presented considerations of using deformable liner ¿ electrode contacts of Z-pinch geometry liners or theta pinch driven liners, in order to have axial access to inject FRC's and to have axial diagnostic access. Since then, we have experimentally implemented the Z-pinch discharge driven deformable liner ¿ electrode contact, obtained full axial coverage radiography of such a liner implosion, and obtained 2D-MHD simulations for a variety of profiled thickness long cylindrical liners. The radiographic results indicate that at least 16 times radial compression of the inner surface of a 0.11 cm thick Al liner was achieved, with a symmetric implosion free of instability growth. We have also made progress in combining 2D-MHD simulations of FRC formation with imploding liner compression of FRC's.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127385600","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}
Pub Date : 2006-10-31DOI: 10.1109/MEGAGUSS.2006.4530670
M. Frese, S. Frese, D. Amdahl, J. Degnan, N. Roderick
Compression of a field-reversed configuration (FRC) by an imploding solid liner is a possible path to magnetized target fusion. It is critical to the success of such experiments to perform full-up multidimensional computational simulations of them. However, there are numerous difficulties in performing those simulations. The interacting physical processes involved introduce disparate time scales. For example, the FRC itself has near-vacuum buffer-field regions that have extremely high Alfven velocity, while the implosion of the liner proceeds at a much slower pace. These strongly differing time scales impose stringent accuracy requirements. The lifetime of an FRC of sufficient density to provide interesting fusion output is on the order of 10 ms while the implosion times of liners of sufficient thickness to survive acceleration to the requisite velocity are somewhat longer than 20 ms. Hence, the FRC must be formed and translated into the liner after the liner implosion begins, so that the FRC formation fields may perturb the liner. Our previous simulations of the experiment have addressed formation separately from the liner implosion and merged the FRC into the liner simulation, preventing proper assessment of this issue. Experimental success hinges on realizing the magnetic inhibition of thermal conduction to prevent loss of plasma energy. Our previous simulations of the final stages of FRC compression have often failed because of inaccuracy in the numerical treatment of the parallel flux. The Rayleigh Taylor instability of the inner surface of the liner during final stages of compression may ultimately limit the performance of this system and must be assessed computationally. However, the modes that grow are those with crests parallel to the FRC's magnetic field, and are not present in the 2-d azimuthally symmetric simulations used for design of the FRC formation and liner implosion. We have made significant progress on these issues. First, we have performed fully integrated, simultaneous simulations of liner implosion and FRC formation on the same grid. These simulations address the generation of rotation in the FRC as well as perturbations of the liner. Second, we have developed a mixed-order numerical treatment of the anisotropic heat conduction that has proven both more robust and more accurate. The improvement has enabled us to run more simulations for design purposes. Finally, we have begun to perform 3-d simulations of the final stages of compression, beginning from the self-consistent state of the 2-d axisymmetric simulation, perturbed in a mass, energy, momentum, and flux conserving .
{"title":"Modeling Liner Compression of FRCs: Obstacles and Advances","authors":"M. Frese, S. Frese, D. Amdahl, J. Degnan, N. Roderick","doi":"10.1109/MEGAGUSS.2006.4530670","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530670","url":null,"abstract":"Compression of a field-reversed configuration (FRC) by an imploding solid liner is a possible path to magnetized target fusion. It is critical to the success of such experiments to perform full-up multidimensional computational simulations of them. However, there are numerous difficulties in performing those simulations. The interacting physical processes involved introduce disparate time scales. For example, the FRC itself has near-vacuum buffer-field regions that have extremely high Alfven velocity, while the implosion of the liner proceeds at a much slower pace. These strongly differing time scales impose stringent accuracy requirements. The lifetime of an FRC of sufficient density to provide interesting fusion output is on the order of 10 ms while the implosion times of liners of sufficient thickness to survive acceleration to the requisite velocity are somewhat longer than 20 ms. Hence, the FRC must be formed and translated into the liner after the liner implosion begins, so that the FRC formation fields may perturb the liner. Our previous simulations of the experiment have addressed formation separately from the liner implosion and merged the FRC into the liner simulation, preventing proper assessment of this issue. Experimental success hinges on realizing the magnetic inhibition of thermal conduction to prevent loss of plasma energy. Our previous simulations of the final stages of FRC compression have often failed because of inaccuracy in the numerical treatment of the parallel flux. The Rayleigh Taylor instability of the inner surface of the liner during final stages of compression may ultimately limit the performance of this system and must be assessed computationally. However, the modes that grow are those with crests parallel to the FRC's magnetic field, and are not present in the 2-d azimuthally symmetric simulations used for design of the FRC formation and liner implosion. We have made significant progress on these issues. First, we have performed fully integrated, simultaneous simulations of liner implosion and FRC formation on the same grid. These simulations address the generation of rotation in the FRC as well as perturbations of the liner. Second, we have developed a mixed-order numerical treatment of the anisotropic heat conduction that has proven both more robust and more accurate. The improvement has enabled us to run more simulations for design purposes. Finally, we have begun to perform 3-d simulations of the final stages of compression, beginning from the self-consistent state of the 2-d axisymmetric simulation, perturbed in a mass, energy, momentum, and flux conserving .","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130710414","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}
Pub Date : 2006-10-01DOI: 10.1109/MEGAGUSS.2006.4530724
R. Lemke, R. Vesey, M. Cuneo, M. Desjarlais, T. Mehlhorn
Using two-dimensional (2D), radiation magnetohydrodynamics (RMHD) numerical simulations, we have designed a feasible z-pinch radiation source that ignites a high yield fuel capsule in a z-pinch driven, double ended hohlraum concept. The z-pinch is composed of nested beryllium (Be) shells and a coaxial, cylindrical foam converter. The z-pinch is designed to produce a shaped radiation pulse that compresses a capsule by a sequence of three shocks without significant entropy increase. We present results of simulations pertaining to the z-pinch design, and discuss conditions that must be achieved in the z-pinch to ensure production of the required radiation pulse.
{"title":"Z-Pinch Requirements for Achieving High Yield Fusion Via A Z-Pinch Driven, Double Ended Hohlraum Concept","authors":"R. Lemke, R. Vesey, M. Cuneo, M. Desjarlais, T. Mehlhorn","doi":"10.1109/MEGAGUSS.2006.4530724","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530724","url":null,"abstract":"Using two-dimensional (2D), radiation magnetohydrodynamics (RMHD) numerical simulations, we have designed a feasible z-pinch radiation source that ignites a high yield fuel capsule in a z-pinch driven, double ended hohlraum concept. The z-pinch is composed of nested beryllium (Be) shells and a coaxial, cylindrical foam converter. The z-pinch is designed to produce a shaped radiation pulse that compresses a capsule by a sequence of three shocks without significant entropy increase. We present results of simulations pertaining to the z-pinch design, and discuss conditions that must be achieved in the z-pinch to ensure production of the required radiation pulse.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131198503","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}
Pub Date : 2006-09-20DOI: 10.1109/MEGAGUSS.2006.4530704
D. White, R. Rieben, B. Wallin
We review the development of a full 3D multiphysics code for the simulation of explosively driven magnetic flux compression generators (MFCG) and related pulse power devices. In a typical MFCG the device is seeded with an initial electric current and the device is then detonated. The detonation compresses the magnetic field and amplifies the current. This is a multiphysics problem in that detonation kinetics, electromagnetic diffusion and induction, material deformation, and thermal effects are all important. This is a tightly coupled problem in that the different physical quantities have comparable spatial and temporal variation, and hence should be solved simultaneously on the same computational mesh.
{"title":"Coupling Magnetic Fields and ALE Hydrodynamics for 3D Simulations of MFCGS","authors":"D. White, R. Rieben, B. Wallin","doi":"10.1109/MEGAGUSS.2006.4530704","DOIUrl":"https://doi.org/10.1109/MEGAGUSS.2006.4530704","url":null,"abstract":"We review the development of a full 3D multiphysics code for the simulation of explosively driven magnetic flux compression generators (MFCG) and related pulse power devices. In a typical MFCG the device is seeded with an initial electric current and the device is then detonated. The detonation compresses the magnetic field and amplifies the current. This is a multiphysics problem in that detonation kinetics, electromagnetic diffusion and induction, material deformation, and thermal effects are all important. This is a tightly coupled problem in that the different physical quantities have comparable spatial and temporal variation, and hence should be solved simultaneously on the same computational mesh.","PeriodicalId":338246,"journal":{"name":"2006 IEEE International Conference on Megagauss Magnetic Field Generation and Related Topics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117100320","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}
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