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Radial electric field 3D modeling for wire arrays driving dynamic hohlraums on Z

Mock, Raymond C.

The anode-cathode structure of the Z-machine wire array results in a higher negative radial electric field (Er) on the wires near the cathode relative to the anode. The magnitude of this field has been shown to anti-correlate with the axial radiation top/bottom symmetry in the DH (Dynamic Hohlraum). Using 3D modeling, the structure of this field is revealed for different wire-array configurations and for progressive mechanical alterations, providing insight for minimizing the negative Er on the wire array in the anode-to-cathode region of the DH. Also, the 3D model is compared to Sasorov's approximation, which describes Er at the surface of the wire in terms of wire-array parameters.

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TYPE SAND Report YEAR 2007
DOIOSTI

A report on IPv6 deployment activities and issues at Sandia National Laboratories:FY2007

Eldridge, John M.; Maestas, Joseph H.; Hu, Tan C.; Tolendino, Lawrence F.

Internet Protocol version 4 (IPv4) has been a mainstay of the both the Internet and corporate networks for delivering network packets to the desired destination. However, rapid proliferation of network appliances, evolution of corporate networks, and the expanding Internet has begun to stress the limitations of the protocol. Internet Protocol version 6 (IPv6) is the replacement protocol that overcomes the constraints of IPv4. As the emerging Internet network protocol, SNL needs to prepare for its eventual deployment in international, national, customer, and local networks. Additionally, the United States Office of Management and Budget has mandated that IPv6 deployment in government network backbones occurs by 2008. This paper explores the readiness of the Sandia National Laboratories network backbone to support IPv6, the issues that must be addressed before a deployment begins, and recommends the next steps to take to comply with government mandates. The paper describes a joint work effort of the Sandia National Laboratories ASC WAN project team and members of the System Analysis & Trouble Resolution, the Communication & Network Systems, and Network System Design & Implementation Departments.

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TYPE SAND Report YEAR 2007
DOIOSTI

Counterion effects on ion mobility and mobile ion concentration of doped polyphosphazene and polyphosphazene ionomers

Macromolecules

Klein, Robert; Welna, Daniel T.; Weikel, Arlin L.; Allcock, Harry R.; Runt, James

A physical model of electrode polarization is applied to dielectric (impedance) data from two poly(methoxyethoxy-ethoxy phenoxyphosphazene) systems with nearly identical chemical structures, one composed of an ionomer with a single mobile cation and the other composed of a salt-doped polymer with mobile cation and mobile anion. Quantitative comparison of the ion mobility and mobile ion concentration, based on chemical structure, is achieved. Both conductivity and ion mobility are reduced to common curves by normalizing T with T g, indicating that Tg of the polymer matrix is a major factor controlling ion diffusion. Even with the use of normalized temperature, both the mobility of ions and the mobile ion concentration in the doped polymers are ∼ 10 times larger than those in the ionomers. These factors arise from faster diffusion of the anion and the local environment surrounding ion pairs. Also, Arrhenius and VFT parameters associated with mobile ion concentration and ion mobility, respectively, reveal differences in activation energies between ionomer and doped polymer that are due to interactions between the ion pairs and polymer segments. © 2007 American Chemical Society.

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TYPE Conference YEAR 2007
ScopusOSTI

Measured radial dependence of the peak sheath voltages present in very high frequency capacitive discharges

Applied Physics Letters

Barnat, E.V.; Miller, Paul A.; Hebner, Gregory A.; Paterson, A.M.; Panagopoulos, Theodoros; Hammond, Edward; Holland, J.

The radial distribution of the measured voltage drop across a sheath formed between a 300 mm electrode and an argon plasma discharge is shown to depend on the excitation radio frequency, under constant power and pressure conditions. At a lower frequency of 13.56 MHz, the voltage drop across the sheath is uniform across the 300 mm electrode, while at higher frequencies of 60 and 162 MHz the voltage drop becomes radially nonuniform. The magnitude and spatial extent of the nonuniformity become greater with increasing frequency. © 2007 American Institute of Physics.

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TYPE Journal Article YEAR 2007
ScopusOSTIDOI

High efficiency DOEs at large diffraction angles for quantum information and computing architectures

Proceedings of SPIE - The International Society for Optical Engineering

Cruz-Cabrera, Alvaro A.; Kemme, Shanalyn A.; Wendt, Joel R.; Kielpinski, D.; Streed, E.W.; Carter, T.R.; Samora, S.

We developed techniques to design higher efficiency diffractive optical elements (DOEs) with large numerical apertures (NA) for quantum computing and quantum information processing. Large NA optics encompass large solid angles and thus have high collection efficiencies. Qubits in ion trap architectures are commonly addressed and read by lasers1. Large-scale ion-trap quantum computing2 will therefore require highly parallel optical interconnects. Qubit readout in these systems requires detecting fluorescence from the nearly isotropic radiation pattern of single ions, so efficient readout requires optical interconnects with high numerical aperture. Diffractive optical element fabrication is relatively mature and utilizes lithography to produce arrays compatible with large-scale ion-trap quantum computer architectures. The primary challenge of DOEs is the loss associated with diffraction efficiency. This is due to requirements for large deflection angles, which leads to extremely small feature sizes in the outer zone of the DOE. If the period of the diffractive is between λ (the free space wavelength) and 10λ, the element functions in the vector regime. DOEs in this regime, particularly between 1.5λ and 4λ, have significant coupling to unwanted diffractive orders, reducing the performance of the lens. Furthermore, the optimal depth of the zones with periods in the vector regime differs from the overall depth of the DOE. We will present results indicating the unique behaviors around the 1.5λ and 4λ periods and methods to improve the DOE performance.

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TYPE Conference YEAR 2007
ScopusOSTI

Active resonant subwavelength grating for scannerless range imaging sensors

Proceedings of SPIE - The International Society for Optical Engineering

Kemme, Shanalyn A.; Boye, Robert; Peters, David; Nellums, Robert N.

We present the design and initial fabrication for a wavelength-agile, high-speed modulator that enables a long-term vision for the THz Scannerless Range Imaging (SRI) sensor. This modulator takes the place of the currently utilized SRI micro-channel plate which is limited to photocathode sensitive wavelengths (primarily in the visible and near-IR regimes). The new component is an active Resonant Subwavelength Grating (RSG). An RSG functions as an extremely narrow wavelength and angular band reflector, or mode selector. Theoretical studies predict that the infinite, laterally-extended RSG can reflect 100% of the resonant light while transmitting the balance of the other wavelengths. Previous experimental realization of these remarkable predictions has been impacted primarily by fabrication challenges. Even so, we have demonstrated large-area (1.0mm) passive RSG reflectivity as high as 100.2%, normalized to deposited gold. In this work, we transform the passive RSG design into an active laser-line modulator.

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TYPE Conference YEAR 2007
ScopusOSTI
Results 81401–81600 of 99,299
Results 81401–81600 of 99,299