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An LTCC 94 GHz Antenna Array

Description: An antenna array is designed in low-temperature cofired ceramic (LTCC) Ferro A6M{trademark} for a mm-wave application. The antenna is designed to operate at 94 GHz with a few percent bandwidth. A key manufacturing technology is the use of 3 mil diameter vias on a 6 mil pitch to construct the laminated waveguides that form the beamforming network and radiating elements. Measurements for loss in the laminated waveguide are presented. The slot-fed cavity-radiating element is designed to account for extremely tight mutual coupling between elements. The array incorporates a slot-fed multi-layer beamforming network.
Date: December 21, 2007
Creator: Aguirre, J; Pao, H; Lin, H; Garland, P; O'Neill, D & Horton, K
Partner: UNT Libraries Government Documents Department

Propagation of guided modes in curved nanoribbon waveguides

Description: The authors develop a plane-wave-based transfer matrix method in curvilinear coordinates to study the guided modes in curved nanoribbon waveguides. The problem of a curved structure is transformed into an equivalent one of a straight structure with spatially dependent tensors of dielectric constant and magnetic permeability. The authors investigate the coupling between the eigenmodes of the straight part and those of the curved part when the waveguide is bent. The authors show that curved sections can result in strong oscillations in the transmission spectrum similar to the recent experimental results of Lawet al.
Date: August 23, 2006
Creator: Yang, P.; Ye, Zhuo; Hu, Xinhua; Li, Ming & Ho, Kai-Ming
Partner: UNT Libraries Government Documents Department


Description: We describe a system able to perform universal stochastic approximations of continuous multivariable functions in both neuron-like and quantum manner. The implementation of this model in the form of multi-barrier multiple-silt system has been earlier proposed. For the simplified waveguide variant of this model it is proved, that the system can approximate any continuous function of many variables. This theorem is also applied to the 2-input quantum neural model analogical to the schemes developed for quantum control.
Date: May 1, 2001
Creator: EZHOV, A.; KHROMOV, A. & BERMAN, G.
Partner: UNT Libraries Government Documents Department

Modeling large heterogeneous RF structures

Description: Large heterogeneous structures are difficult to model on a numerical grid because of the limitations on computing resources, so that alternate approaches such as equivalent circuits and mode-matching have been developed to treat this problem. This paper will describe the three methods and will analyze a structure representative of the SLAC and JLC detuned structures to compare the efficacy of each approach.
Date: November 1, 1996
Creator: Li, Zenghai; Ko, Kwok; Srinivas, V. & Higo, Toshiyasu
Partner: UNT Libraries Government Documents Department

High-power Waveguide Dampers for the Short-Pulse X-Ray Project at the Advanced Photon Source

Description: High-power waveguide dampers have been designed and prototyped for the Short-Pulse X-ray (SPX) cavities at the Advanced Photon Source. The cavities will operate at 2.815 GHz and utilize the TM110 dipole mode. As a result, higher-order (HOM) and lower-order mode (LOM) in-vacuum dampers have been designed to satisfy the demanding broadband damping requirements in the APS storage ring. The SPX single-cell cavity consists of two WR284 waveguides for damping the HOMs and one WR284 waveguide for primarily damping the LOM where up to 2kW will be dissipated in the damping material. The damper designs and high-power experimental results will be discussed in this paper.
Date: July 1, 2012
Creator: Waldschmidt, G. J.; Liu, J.; Middendorf, M. E.; Nassiri, A.; Smith, T. L.; Wu, G..= et al.
Partner: UNT Libraries Government Documents Department

Recent Results from a Folded Waveguide ICRF Antenna Development Project

Description: Preliminary high power tests have been performed on a folded waveguide (FWG) ICRF launcher with a curved coupling faceplate installed. Two alternative faceplate configurations have been built and tested at low power and will be tested at high power in the near future. The new designs include a dipole plate which provides a 0-<font face="symbol">p</font> launch spectrum and a more transparent, flexible monopole face plate configuration. This FWG design is a 12 vane, 57 MHz design with a 0.31 m square cross section. The FWG can be installed with either fast wave or ion-Bernstein wave polarization and can also be retracted behind a vacuum isolation valve. A 1 x 4 FWG array optimized for fast wave current drive on DIII-D has been conceptualized.
Date: April 12, 1999
Creator: Baity, F.W.; Barber, G.C.; Bigelow, T.S.; Carter, M.D.; Fadnek, A.; Ryan, P.M. et al.
Partner: UNT Libraries Government Documents Department

The integration of advanced photonics and MEMS : LDRD 26519 final report.

Description: In this work we have demonstrated the fabrication of two different classes of devices which demonstrate the integration of simple MEMS structures with photonics structures. In the first class of device a suspended, movable Si waveguide was designed and fabricated. This waveguide was designed to be able to be actuated so that it could be brought into close proximity to a ring resonator or similar structure. In the course of this work we also designed a technique to improve the input coupling to the waveguide. While these structures were successfully fabricated, post fabrication and testing involved a significant amount of manipulation of the devices and due to their relatively flimsy nature our structures could not readily survive this extra handling. As a result we redesigned our devices so that instead of moving the waveguides themselves we moved a much smaller optical element into close proximity to the waveguides. Using this approach it was also possible to fabricate a much larger array of actively switched photonic devices: switches, ring resonators, couplers (which act as switches or splitters) and attenuators. We successfully fabricated all these structures and were able to successfully demonstrate splitters, switches and attenuators. The quality of the SiN waveguides fabricated in this work were found to be qualitatively compatible to those made using semiconductor materials.
Date: December 1, 2003
Creator: Fleming, James Grant & Lin, Shawn-Yu
Partner: UNT Libraries Government Documents Department

High Peak Power Gain Switched Flared Waveguide Lasers

Description: We gain-switch flared waveguide lasers to obtain 14.5 W peak powers and 0.5 nJ pulse energies with laser structures compatible with the generation of diffraction-limited beams. The results are in excellent agreement with a microscopic laser model.
Date: August 5, 1999
Creator: Chow, W.W.; Indik, R.; Koch, S.W.; Mar, Alan, Vawter, G. Allen & Moloney, J.
Partner: UNT Libraries Government Documents Department

Compact Probe for Power Detection from the Narrow Side of the Waveguide

Description: Phased array antennas with high directivity have a variety of applications. One of their applications is in RF heating for magnetically confined plasma fusion research. Among these RF heating schemes, waveguide arrays with careful phase control on each waveguide can act as a phased array antenna to deliver megawatts of power for heating fusion plasmas in the lower-hybrid range of frequencies (1 GHz-10 GHz). In order to achieve compactness, it is common to stack reduced height waveguide together to form the waveguide array. As long as the delivered power does not cause arcing in the waveguide, the waveguide height can be quite small. Due to this confined space in a stack of reduced height waveguides, power detection of the incident and reflected wave in the reduced height waveguide is extremely difficult. A new compact probe, which employs current loops, to monitor the incident and reflected wave from the narrow side of the reduced height waveguide has been developed. Its theory and performance will be reported in this paper.
Date: May 7, 2004
Creator: Kung, C.C.; Bernabei, S.; Gumbas, J.; Greenough, N.; Fredd, E.; Wilson, J.R. et al.
Partner: UNT Libraries Government Documents Department

Web-interfaced Nonlinear Optical Waveguide and Photonic Crystal Simulator

Description: We report on the development of new methods for the computation of spectral bandpass properties of photonic crystals and for the electromagnetic wave propagation in second order nonlinear optical waveguides. The former is based on a generalization of characteristic matrices while the latter is based on path integrals. Accurate and efficient propagation methods and algorithms form the basis for the construction of design tools for integrated optics.
Date: June 15, 2002
Creator: Enguehard, S. & Hatfield, B.
Partner: UNT Libraries Government Documents Department

Reconfigurable high-power rf system in the APS

Description: The 352-MHz high-power system for the Advanced Photon Source (APS) storage ring and booster synchrotron has been configured to allow two to four klystrons to power the storage ring and one klystron to power the booster. A quadrature hybrid combines two klystron out-puts with two 45{degrees} phase shifters at each output of the hybrid for proper phasing at the storage ring cavities for the selected mode. The phase shifters in the hybrid outputs and three waveguide switches are used to choose an operation mode in any one of twelve possible configurations using three to five klystrons to power the storage ring and booster. The system can be configured to use one klystron as the power source of a test station.
Date: August 1, 1997
Creator: Kang, Y.W. & Horan, D.
Partner: UNT Libraries Government Documents Department

Far-field radiation from a cleaved cylindrical dielectric waveguide

Description: Angular spread in the far-field radiation pattern of a cleaved dielectric waveguide is determined from the modal structure at the surface of the waveguide using the Smythe vector integral formulation. Essential features: First, a mode exists in the fiber that has no wavelength cutoff--the so-called HE{sub 11} mode. This mode arises when non-azimuthal angular dependence of the incoming radiation is present. Second, the energy flow from this hybrid mode fills the fiber face and is not annularly shaped as opposed to the symmetric TE and TM modes. Third, the HE{sub 11} mode is not polarization dependent in contrast to the TE and TM modes. Fourth, for small differences in the refractive indices between the core and cladding regions, only the HE{sub 11} mode will be supported until the next modes appear around 3.33{lambda}. At this point, three new modes can propagate and the model structure of the radiation becomes more complicated. Fifth, the far-field radiation pattern will have negligibly small angular dependence in the phases of the vector fields when only the lowest mode is present; the amplitude has an overall angular dependent form factor. Furthermore, when other modes are present (above 3.33{lambda}), the phase of the vector fields will acquire an angular dependence.
Date: July 9, 1996
Creator: Cerjan, C.
Partner: UNT Libraries Government Documents Department

High power, high frequency, vacuum flange

Description: This invention is comprised of an improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counterbores surrounding the waveguide tubes. When the sections are bolted together the counterbores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.
Date: December 31, 1991
Creator: Felker, B. & McDaniel, M.
Partner: UNT Libraries Government Documents Department

LEDA RF distribution system design and component test results

Description: The 350 MHz and 700 MHz RF distribution systems for the Low Energy Demonstration Accelerator (LEDA) have been designed and are currently being installed at Los Alamos National Laboratory. Since 350 MHz is a familiar frequency used at other accelerator facilities, most of the major high-power components were available. The 700 MHz, 1.0 MW, CW RF delivery system designed for LEDA is a new development. Therefore, high-power circulators, waterloads, phase shifters, switches, and harmonic filters had to be designed and built for this applications. The final Accelerator Production of Tritium (APT) RF distribution systems design will be based on much of the same technology as the LEDA systems and will have many of the RF components tested for LEDA incorporated into the design. Low power and high-power tests performed on various components of these LEDA systems and their results are presented here.
Date: December 31, 1998
Creator: Roybal, W.T.; Rees, D.E.; Borchert, H.L.; McCarthy, M. & Toole, L.
Partner: UNT Libraries Government Documents Department

Initial results from a folded waveguide ICRF antenna development project

Description: A folded waveguide (FWG) ICRF launcher has been built and preliminary high power tests completed. This project is intended to provide a proof-of-principle test, using a high density plasma load, of the high power density capability and other ITER-relevant advanced features of the FWG. The design is a 12 vane, 57 MHz unit with a quarter-wavelength resonator configuration. This FWG has a 0.31 m square cross section that can be installed with either fast wave or ion-Bernstein wave polarization and can also be retracted behind a vacuum isolation valve. A primary issue to be addressed by this project is the plasma loading and maximum power capability of the FWG. Initial high power tests on the ORNL Radio Frequency Test Facility have been conducted. Modeling of the FWG electromagnetic fields and calculations of loading have been performed as well as an investigation of alternate face plate designs that improve the coupling by allowing greater magnetic field penetration into the plasma. This FWG was originally designed for TFTR or PBX-M and is now being considered for the DIII-D tokamak at GA, the NSTX small aspect ratio device under construction at PPPL and the possible FSX experiment at PPPL.
Date: August 1, 1997
Creator: Bigelow, T.S.; Cole, M.J. & Fadnek, A.
Partner: UNT Libraries Government Documents Department

Formation of novel optical materials by ion implantation

Description: Ion implantation into glasses shows considerable promise as a technique for producing novel materials having unique optical properties. There is also significant commercial interest in the marketing of optical waveguides, high-performance polarizing glasses, and birefringent glasses. In this work, special glass compositions, including both two-phase and anisotropic materials, were prepared by bulk processing techniques and then implanted with Ag, Au, and Cu ions at different temperatures, energies, and doses. The composite materials produced showed strong resonant absorption at the surface plasmon resonance frequency. The plasmon frequency was consistent with the formation of spherical colloids of the implanted metals having diameters on the order of 10 nm. No anisotropic behavior of the implanted materials was observed. Possible applications for these materials, had such anisotropy been developed, would have included optical isolators, Faraday rotators, optical waveguides, and switching devices for use in optical communication and computing.
Date: October 1, 1995
Partner: UNT Libraries Government Documents Department

Design options for an ITER ion cyclotron system

Description: Recent changes have occurred in the design requirements for the ITER ion cyclotron system, requiring in-port launchers in four main horizontal ports to deliver 50 MW of power to the plasma. The design is complicated by the comparatively large antenna-separatrix distance of 10--20 cm. Designs of a conventional strap launcher and a folded waveguide launcher than can meet the new requirements are presented.
Date: September 1, 1995
Creator: Swain, D.W.; Baity, F.W.; Bigelow, T.S.; Ryan, P.M.; Goulding, R.H.; Carter, M.D. et al.
Partner: UNT Libraries Government Documents Department

Compact X-band high power load using magnetic stainless steel

Description: We present design and experimental results of a high power X-band load. The load is formed as a disk-loaded waveguide structure using lossy, Type 430 stainless steel. The design parameters have been optimized using the recently developed mode-matching code MLEGO. The load has been designed for compactness while maintaining a band width greater than 300 MHz.
Date: May 1, 1995
Creator: Tantawi, S.G. & Vlieks, A.E.
Partner: UNT Libraries Government Documents Department