Publications

84 Results
Skip to search filters

Penetration Bounds For Azimuthal Slot On Infinite Cylinder With Finite Length Backing Cylindrical Cavity

Warne, Larry K.; Campione, Salvatore; Martin, Luis S.; Pack, Alden R.; Langston, William L.; Zinser, Brian &.

We examine coupling into azimuthal slots on an infinite cylinder with a infinite length interior cavity operating both at the fundamental cavity modal frequencies, with small slots and a resonant slot, as well as higher frequencies. The coupling model considers both radiation on an infinite cylindrical exterior as well as a half space approximation. Bounding calculations based on maximum slot power reception and interior power balance are also discussed in detail and compared with the prior calculations. For higher frequencies limitations on matching are imposed by restricting the loads ability to shift the slot operation to the nearest slot resonance; this is done in combination with maximizing the power reception as a function of angle of incidence. Finally, slot power mismatch based on limited cavity load quality factor is considered below the first slot resonance.

More Details

Penetration through slots in cylindrical cavities with cavity modes overlapping with the first slot resonance

Electromagnetics

Campione, Salvatore; Warne, Larry K.; Langston, William L.; Gutierrez, Roy K.; Hicks, Jeorge W.; Reines, Isak C.; Pfeiffer, Robert A.; Himbele, John J.; Williams, Jeffery T.

We analyze the coupling into a slotted cylindrical cavity operating at fundamental cavity modal frequencies overlapping with the slot’s first resonance frequency through an unmatched formulation that accounts for the slot’s absorption and radiation processes. The model is validated through full-wave simulations and experimental data. We then couple the unmatched formulation to a perturbation theory model to investigate an absorber within the cavity to reduce the interior field strength, also validated with full-wave simulations and experiments. These models are pivotal to understanding the physical processes involved in the electromagnetic penetration through slots, and may constitute design tools to mitigate electromagnetic interference effects within cavities.

More Details

Penetration through Slots in Cylindrical Cavities Operating at Fundamental Cavity Modes

IEEE Transactions on Electromagnetic Compatibility

Campione, Salvatore; Warne, Larry K.; Langston, William L.; Pfeiffer, Robert A.; Martin, Nevin S.; Williams, Jeffery T.; Gutierrez, Roy K.; Reines, Isak C.; Huerta, Jose G.; Dang, Vinh Q.

In this article, we examine the coupling into an electrically short azimuthal slot on a cylindrical cavity operating at fundamental cavity modal frequencies. We first develop a matched bound formulation through which we can gather information for maximum achievable levels of interior cavity fields. Actual field levels are below this matched bound; therefore, we also develop an unmatched formulation for frequencies below the slot resonance to achieve a better insight on the physics of this coupling. Good agreement is observed between the unmatched formulation, full-wave simulations, and experimental data, providing a validation of our analytical models. We then extend the unmatched formulation to treat an array of slots, found again in good agreement with full-wave simulations. These analytical models can be used to investigate ways to mitigate electromagnetic interference and electromagnetic compatibility effects within cavities.

More Details

An Approximate Direct Inverse as a Preconditioner for Ill-conditioned Problems

2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, IEEECONF 2020 - Proceedings

Lee, Chung H.; Lee, Jin F.; Langston, William L.; Zinser, Brian; Dang, Vinh Q.; Huang, Andy H.; Campione, Salvatore

This paper implemented an approximate direct inverse for the surface integral equation including multilevel fast-multipole method. We apply it as a preconditioner to two examples suffering convergence problem with an iterative solver.

More Details

Multipole-based cable braid electromagnetic penetration model: Magnetic penetration case

Progress In Electromagnetics Research C

Campione, Salvatore; Warne, Larry K.; Langston, William L.

The goal of this paper is to present, for the first time, calculations of the magnetic penetration case of a first principles multipole-based cable braid electromagnetic penetration model. As a first test case, a one-dimensional array of perfect electrically conducting wires, for which an analytical solution is known, is investigated: We compare both the self-inductance and the transfer inductance results from our first principles cable braid electromagnetic penetration model to those obtained using the analytical solution. These results are found in good agreement up to a radius to half spacing ratio of about 0.78, demonstrating a robustness needed for many commercial and non-commercial cables. We then analyze a second set of test cases of a square array of wires whose solution is the same as the one-dimensional array result and of a rhomboidal array whose solution can be estimated from Kley’s model. As a final test case, we consider two layers of one-dimensional arrays of wires to investigate porpoising effects analytically. We find good agreement with analytical and Kley’s results for these geometries, verifying our proposed multipole model. Note that only our multipole model accounts for the full dependence on the actual cable geometry which enables us to model more complicated cable geometries.

More Details

Modeling shielded cables in Xyce based on transmission-line theory

2019 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), USNC-URSI 2019 - Proceedings

Campione, Salvatore; Pung, Aaron J.; Warne, Larry K.; Langston, William L.; Mei, Ting M.

Electromagnetic shields are usually employed to protect cables and other devices; however, these are generally not perfect, and may permit external magnetic and electric fields to penetrate into the interior regions of the cable, inducing unwanted current and voltages. The aim of this paper is to verify a circuit model tool with our previously proposed analytical model [1] for evaluating currents and voltages induced in the inner conductor of braided-shield cables. This circuit model will enable coupling between electromagnetic and circuit simulations.

More Details

First principles model of electric and magnetic cable braid penetrations

2018 International Applied Computational Electromagnetics Society Symposium in Denver, ACES-Denver 2018

Campione, Salvatore; Warne, Larry K.; Langston, William L.

In this paper, we report our recent findings about a first principles, multipole-based model of electric and magnetic cable braid penetrations. We consider for brevity a one-dimensional array of wires, but the model can be readily applied to realistic cable geometries. Comparisons between the first principles method and analytical formulas will be provided for both electric and magnetic penetration cases. These comparisons confirm that our first principles model works within the geometric characteristics of many commercial cables.

More Details

Massively parallel frequency domain electromagnetic simulation codes

2018 International Applied Computational Electromagnetics Society Symposium in Denver, ACES-Denver 2018

Langston, William L.; Kotulski, J.D.; Coats, Rebecca S.; Jorgenson, Roy E.; Blake, S.A.; Campione, Salvatore; Pung, Aaron J.; Zinser, Brian

This paper provides an overview of the electromagnetic frequency domain simulation capabilities of the Electromagnetic Theory department at Sandia National Laboratories via a description of two of its codes. EIGER is a Method of Moments code for electromagnetic simulations, but it only runs on traditional CPUs, not on new architectures. Gemma is in development to replace EIGER and will run on many architectures, including CPUs, GPUs, and MICs, by leveraging the Kokkos library.

More Details

First principles model of electric cable braid penetration with dielectrics

Progress In Electromagnetics Research C

Campione, Salvatore; Warne, Larry K.; Langston, William L.; Basilio, Lorena I.

In this paper, we report the formulation to account for dielectrics in a first principles multipole-based cable braid electromagnetic penetration model. To validate our first principles model, we consider a one-dimensional array of wires, which can be modeled analytically with a multipole-conformal mapping expansion for the wire charges; however, the first principles model can be readily applied to realistic cable geometries. We compare the elastance (i.e., the inverse of the capacitance) results from the first principles cable braid electromagnetic penetration model to those obtained using the analytical model. The results are found in good agreement up to a radius to half spacing ratio of 0.5–0.6, depending on the permittivity of the dielectric used, within the characteristics of many commercial cables. We observe that for typical relative permittivities encountered in braided cables, the transfer elastance values are essentially the same as those of free space; the self-elastance values are also approximated by the free space solution as long as the dielectric discontinuity is taken into account for the planar mode.

More Details

A first principles cable braid electromagnetic penetration model

Proceedings of the 2017 19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017

Campione, Salvatore; Warne, Larry K.; Coats, Rebecca S.; Langston, William L.; Basilio, Lorena I.; Johnson, W.A.

We propose a cable braid electromagnetic penetration model that is based on first-principles and is derived strictly from the geometrical parameters of the cable in question. We apply this formulation to the case of a one-dimensional array of wires, which can also be modeled analytically via a multipole-conformal mapping expansion for the wire charges and is extended by means of Laplace solutions in bipolar coordinates. Both electric and magnetic penetrations are analyzed, and comparisons are performed between results from the first principles cable braid electromagnetic penetration model and those obtained using the multipole-conformal mapping expansion method. We find results in very good agreement when using up to the octopole moment (for the first principles model), covering a dynamic range of radius-to-half-spacing ratio up to 0.6. These results give us the confidence that our first principles model is applicable to the geometric characteristics of many commercial cables.

More Details

Multipole-Based Cable Braid Electromagnetic Penetration Model: Electric Penetration Case

IEEE Transactions on Electromagnetic Compatibility

Campione, Salvatore; Warne, Larry K.; Langston, William L.; Johnson, William A.; Coats, Rebecca S.; Basilio, Lorena I.

In this paper, we investigate the electric penetration case of the first principles multipole-based cable braid electromagnetic penetration model reported in the Progress in Electromagnetics Research B 66, 63–89 (2016). We first analyze the case of a 1-D array of wires: this is a problem which is interesting on its own, and we report its modeling based on a multipole-conformal mapping expansion and extension by means of Laplace solutions in bipolar coordinates. We then compare the elastance (inverse of capacitance) results from our first principles cable braid electromagnetic penetration model to that obtained using the multipole-conformal mapping bipolar solution. These results are found in a good agreement up to a radius to half spacing ratio of 0.6, demonstrating a robustness needed for many commercial cables. We then analyze realistic cable implementations without dielectrics and compare the results from our first principles braid electromagnetic penetration model to the semiempirical results reported by Kley in the IEEE Transactions on Electromagnetic Compatibility 35, 1–9 (1993). Finally, although we find results on the same order of magnitude of Kley's results, the full dependence on the actual cable geometry is accounted for only in our proposed multipole model which, in addition, enables us to treat perturbations from those commercial cables measured.

More Details

Broken Symmetry Dielectric Resonators for High Quality Factor Fano Metasurfaces

ACS Photonics

Campione, Salvatore; Liu, Sheng L.; Basilio, Lorena I.; Warne, Larry K.; Langston, William L.; Luk, Ting S.; Wendt, J.R.; Reno, J.L.; Keeler, Gordon A.; Brener, Igal; Sinclair, Michael B.

We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple "bright" dipole modes to "dark" dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurface that achieves a quality factor of ∼1300 at ∼10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (∼1 μm): a silicon-based implementation that achieves a quality factor of ∼350; and a gallium arsenide-based structure that achieves a quality factor of ∼600, the highest near-infrared quality factor experimentally demonstrated to date with this kind of metasurface. Importantly, large electromagnetic field enhancements appear within the resonators at the Fano resonant frequencies. We envision that combining high quality factor, high field enhancement resonances with nonlinear and active/gain materials such as gallium arsenide will lead to new classes of active optical devices.

More Details

Transmission-line modeling of shielding effectiveness of multiple shielded cables with arbitrary terminations

2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016

Campione, Salvatore; Basilio, Lorena I.; Warne, Larry K.; Langston, William L.

Cable shielding to protect against coupling of electromagnetic radiation into a component or circuit, particularly over large frequency bands, is at times a challenging task. It is general understanding that increasing the number of shields of a cable will improve the shielding performance. However, there are situations in which a cable with multiple shields may perform similar to or in some cases worse than a cable with a single shield, and this analysis has seldom been discussed in the literature. We intend to shed more light onto this topic in this paper.

More Details

Tailoring dielectric resonator geometries for directional scattering, Huygens' metasurfaces, and high quality-factor Fano resonances

2016 URSI International Symposium on Electromagnetic Theory, EMTS 2016

Campione, Salvatore; Basilio, Lorena I.; Warne, Larry K.; Langston, William L.; Luk, Ting S.; Wendt, J.R.; Liu, Sheng L.; Brener, Igal B.; Sinclair, Michael B.

Metamaterial dielectric resonators represent a promising path toward low-loss metamaterials at optical frequencies. In this paper we utilize perturbations of high symmetry resonator geometries, such as cubes, either to overlap the electric and magnetic dipole resonances, thereby enabling directional scattering and Huygens' metasurfaces, or to induce couplings between the otherwise orthogonal resonator modes to achieve high-quality factor Fano resonances. Our results are fully scalable across any frequency bands where high-permittivity dielectric materials are available, including microwave, THz, and infrared frequencies.

More Details

A bound on electromagnetic penetration through a slot aperture with backing cavity

Warne, Larry K.; Jorgenson, Roy E.; Williams, Jeffery T.; Basilio, Lorena I.; Coats, Rebecca S.; Campione, Salvatore; Chen, Kenneth C.; Langston, William L.

This report examines bounds on the penetrant power through ports of entry into a conductive cavity. We first replace the cavity by a load and consider the maximum power transfer properties of an antenna or an aperture. We consider how limitations on the load quality factor place limits on received power. For general frequency ranges we model the backing region by means of a uniformly distributed matched load along a slot aperture and adjust its value for maximum power transfer. This result is derived in closed form using a transmission line model for the aperture. This result illustrates the reduction in received power for low frequencies with finitely conducting wall materials. At high frequencies it approaches the receiving cross section of a linear array having the slot length dimension. Next we examine a slot aperture in a conducting rectangular enclosure and determine how the cavity wall losses and resulting quality factor limit the penetrant power. Detailed simulations and experimental measurements are compared with each other and with the bounding results to assess the accuracy of the bounds. These comparisons also indicate limitations on the accuracy of the models due to perturbing influences in construction, such as bolted joints.

More Details

Shielding effectiveness of multiple-shield cables with arbitrary terminations via transmission line analysis

Progress In Electromagnetics Research C

Campione, Salvatore; Basilio, Lorena I.; Warne, Larry K.; Hudson, Howard G.; Langston, William L.

In this paper we report on a transmission-line model for calculating the shielding effectiveness of multiple-shield cables with arbitrary terminations. Since the shields are not perfect conductors and apertures in the shields permit external magnetic and electric fields to penetrate into the interior regions of the cable, we use this model to estimate the effects of the outer shield current and voltage (associated with the external excitation and boundary conditions associated with the external conductor) on the inner conductor current and voltage. It is commonly believed that increasing the number of shields of a cable will improve the shielding performance. However, this is not always the case, and a cable with multiple shields may perform similar to or in some cases worse than a cable with a single shield. We want to shed more light on these situations, which represent the main focus of this paper.

More Details

First principles cable braid electromagnetic penetration model

Progress In Electromagnetics Research B

Warne, Larry K.; Langston, William L.; Basilio, Lorena I.; Johnson, William A.

The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also set up in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multipoles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplified infinite periodic planar geometry. This is used to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.

More Details

Cable Braid Electromagnetic Penetration Model

Warne, Larry K.; Langston, William L.; Basilio, Lorena I.; Johnson, W.A.

The model for penetration of a wire braid is rigorously formulated. Integral formulas are developed from energy principles and reciprocity for both self and transfer immittances in terms of potentials for the fields. The detailed boundary value problem for the wire braid is also setup in a very efficient manner; the braid wires act as sources for the potentials in the form of a sequence of line multipoles with unknown coefficients that are determined by means of conditions arising from the wire surface boundary conditions. Approximations are introduced to relate the local properties of the braid wires to a simplified infinite periodic planar geometry. This is used in a simplified application of reciprocity to be able to treat nonuniform coaxial geometries including eccentric interior coaxial arrangements and an exterior ground plane.

More Details

Full-wave simulation of a three-dimensional metamaterial prism

Microwave and Optical Technology Letters

Basilio, Lorena I.; Langston, William L.; Warne, Larry K.; Langston, William L.; Sinclair, Michael B.

In this article, a negative-index metamaterial prism based on a composite unit cell containing a split-ring resonator and a z-dipole is designed and simulated. The design approach combines simulations of a single unit cell to identify the appropriate cell design (yielding the desired negative-index behavior) together with subcell modeling (which simplifies the mesh representation of the resonator geometry and allows for a larger number of resonator cells to be handled). In addition to describing the methodology used to design a n = -1 refractive index prism, results including the effective-medium parameters, the far-field scattered patterns, and the near-zone field distributions corresponding to a normally incident plane-wave excitation of the prism are presented.

More Details

Design and simulation of a 3-dimensional metamaterial prism

2014 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), USNC-URSI 2014 - Proceedings

Basilio, Lorena I.; Langston, William L.; Warne, Larry K.

The goal of this paper is to define a unit cell containing an electric and magnetic complement and degenerate pair of resonators and subsequently construct a 3-dimensional (3D) n = -1 refractive index prism based upon the final unit cell design. In this effort simulating and observing the response of a negative-index metamaterial (MM) prism to a plane-wave excitation was a primary intent. However, an equally-important goal was to develop an efficient and high-fidelity process for arriving at the prism design.

More Details

Electromagnetic coupling into two standard calibration shields on the Sandia cable tester

Warne, Larry K.; Basilio, Lorena I.; Langston, William L.; Chen, Kenneth C.

This report presents analytic transmission line models for calculating the shielding effectiveness of two common calibration standard cables. The two cables have different canonical aperture types, which produce the same low frequency coupling but different responses at resonance. The dominant damping mechanism is produced by the current probe loads at the ends of the cables, which are characterized through adaptor measurements. The model predictions for the cables are compared with experimental measurements and good agreement between the results is demonstrated. This setup constitutes a nice repeatable geometry that nevertheless exhibits some of the challenges involved in modeling non-radio frequency geometries.

More Details

Loop-to-loop coupling

Warne, Larry K.; Basilio, Lorena I.; Langston, William L.; Salazar, Robert S.; Coleman, Phillip D.; Lucero, Larry M.

This report estimates inductively-coupled energy to a low-impedance load in a loop-to-loop arrangement. Both analytical models and full-wave numerical simulations are used and the resulting fields, coupled powers and energies are compared. The energies are simply estimated from the coupled powers through approximations to the energy theorem. The transmitter loop is taken to be either a circular geometry or a rectangular-loop (stripline-type) geometry that was used in an experimental setup. Simple magnetic field models are constructed and used to estimate the mutual inductance to the receiving loop, which is taken to be circular with one or several turns. Circuit elements are estimated and used to determine the coupled current and power (an equivalent antenna picture is also given). These results are compared to an electromagnetic simulation of the transmitter geometry. Simple approximate relations are also given to estimate coupled energy from the power. The effect of additional loads in the form of attached leads, forming transmission lines, are considered. The results are summarized in a set of susceptibility-type curves. Finally, we also consider drives to the cables themselves and the resulting common-to-differential mode currents in the load.

More Details

A Summary of the Theory and Design Team Efforts for the Sandia Metamaterials Science and Technology Grand Challenge LDRD

Basilio, Lorena I.; Brener, Igal B.; Burckel, David B.; Shaner, Eric A.; Wendt, J.R.; Luk, Ting S.; Ellis, A.R.; Bender, Daniel A.; Clem, Paul G.; Rasberry, Roger D.; Langston, William L.; Ihlefeld, Jon I.; Dirk, Shawn M.; Warne, Larry K.; Peters, D.W.; El-Kady, I.; Reinke, Charles M.; Loui, Hung L.; Williams, Jeffery T.; Sinclair, Michael B.; McCormick, Frederick B.

Abstract not provided.

New self-magnetically insulated connection of multi-level accelerators to a common load

Digest of Technical Papers-IEEE International Pulsed Power Conference

VanDevender, J.P.; Langston, William L.; Pasik, Michael F.; Coats, Rebecca S.; Pointon, Timothy D.; Seidel, David B.; Jennings, C.A.; McKee, G.R.; Schneider, Larry X.

We have developed a new type of convolute called the Clam Shell MITL (CSMITL) to couple multi-level accelerators to a common load. The CSMITL has magnetic nulls only at large radius where the cathode electric field is kept below the threshold for emission, has only a simply connected magnetic topology to avoid plasma motion along magnetic field lines into highly stressed gaps, and has electron injectors that ensure efficient electron flow even in the limiting case of self-limited MITLs. We report the first experimental results on a CSMITL, which convolutes two disk feeds on the Saturn accelerator into a single disk feed. Experiments with a high impedance electron beam load operating at twice the self-limited impedance of the CSMITL confirm key design features and demonstrate robust operation. © 2011 IEEE.

More Details

Modeling Braided Shields via multipole representations for the braid charges and currents

Proceedings - 2011 International Conference on Electromagnetics in Advanced Applications, ICEAA'11

Johnson, William Arthur.; Langston, William L.; Basilio, Lorena I.; Warne, Larry K.

A first principles calculation for the transfer capacitance of a Beldon cable is carried out by the use of filamentary constant, dipole, quadrupole, and octopole unknown charges placed at the center of each braid wire. Results are compared with full electrostatic simulations and a phenomenological model. © 2011 IEEE.

More Details

A negative-index metamaterial design based on metal-core, dielectric shell resonators

IEEE Antennas and Propagation Society, AP-S International Symposium (Digest)

Basilio, L.I.; Warne, Larry K.; Langston, William L.; Johnson, William Arthur.; Sinclair, M.B.

In this paper a simple effective-media analysis (including higher-order multipoles) is used to design a single-resonator, negative-index design based on a metal-core, dielectric-shell (MCDS) unit cell. In addition to comparing the performance of the MCDS design to other core-shell negative-index designs, performance trade-offs resulting from the relative positioning of the electric and magnetic modal resonances in the MCDS design are also discussed. © 2011 IEEE.

More Details

Modeling of general 1-D periodic leaky-wave antennas in layered media using EIGER™

Proceedings - 2010 12th International Conference on Electromagnetics in Advanced Applications, ICEAA'10

Johnson, W.A.; Paulotto, S.; Jackson, D.R.; Wilton, D.R.; Langston, William L.; Basilio, Lorena I.; Baccarelli, P.; Valerio, G.; Celepcikay, F.T.

This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER™ code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case. ©2010 IEEE.

More Details

Modeling of general 1-D periodic leaky-wave antennas in layered media using EIGER

Langston, William L.; Basilio, Lorena I.

This paper presents a mixed-potential integral-equation formulation for analyzing 1-D periodic leaky-wave antennas in layered media. The structures are periodic in one dimension and finite in the other two dimensions. The unit cell consists of an arbitrary-shaped metallic/dielectric structure. The formulation has been implemented in the EIGER{trademark} code in order to obtain the real and complex propagation wavenumbers of the bound and leaky modes of such structures. Validation results presented here include a 1-D periodic planar leaky-wave antenna and a fully 3-D waveguide test case.

More Details

An effective media toolset for use in metamaterial design

Warne, Larry K.; Johnson, William Arthur.; Langston, William L.; Sinclair, Michael B.

This paper introduces an effective-media toolset that can be used for the design of metamaterial structures based on metallic components such as split-ring resonators and dipoles, as well as dielectric spherical resonators. For demonstration purposes the toolset will be used to generate infrared metamaterial designs, and the predicted performances will be verified with full-wave numerical simulations.

More Details

Resonant coupling to a dipole absorber inside a metamaterial: Anticrossing of the negative index response

Journal of Vacuum Science and Technology B

Smolev, Svyatoslav; Ku, Zahyun; Brueck, S.R.J.; Brener, Igal B.; Sinclair, Michael B.; Ten Eyck, Gregory A.; Langston, William L.; Basilio, Lorena I.

The authors experimentally demonstrate a resonant hybridization between the magnetic dipole structural resonance in the permeability of a fishnet metamaterial and an electric dipole material resonance in the permittivity of the dielectric spacer layer. The hybrid resonances in the permeability and the negative index response exhibit an anticrossing behavior. A simple analytic model and numerical simulations using a rigorous coupled-wave analysis are in excellent qualitative agreement with the experiment. © 2010 American Vacuum Society.

More Details

Quasi-spherical direct drive fusion

Nash, Thomas J.; McDaniel, Dillon H.; Langston, William L.

The authors present designs of quasi-spherical direction drive z-pinch loads for machines such as ZR at 28 MA load current with a 150 ns implosion time (QSDDI). A double shell system for ZR has produced a 2D simulated yield of 12 MJ, but the drive for this system on ZR has essentially no margin. A double shell system for a 56 MA driver at 150 ns implosion has produced a simulated yield of 130 MJ with considerable margin in attaining the necessary temperature and density-radius product for ignition. They also represent designs for a magnetically insulated current amplifier, (MICA), that modify the attainable ZR load current to 36 MA with a 28 ns rise time. The faster pulse provided by a MICA makes it possible to drive quasi-spherical single shell implosions (QSDD2). They present results from 1D LASNEX and 2D MACH2 simulations of promising low-adiabat cryogenic QSDD2 capsules and 1D LASNEX results of high-adiabat cryogenic QSDD2 capsules.

More Details
84 Results
84 Results