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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

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

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

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


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

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

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


Description: After the design optimization of a squashed elliptical shape, single-cell, superconducting (SC) deflecting cavity at 2.815 GHz, a copper prototype has been bench measured to determine its rf properties and the effectiveness of waveguide damping of parasitic modes [1]. RF cold tests were also performed at 2K on niobium single-cell and two-cell prototype cavities. Details of impedance calculation using wakefiled analysis of the single-cell cavity are shown to meet the strict 200 mA beam stability requirement of the Advanced Photon Source (APS) at Argonne National Lab where a total of 16 single-cell cavities will be divided into two cryomodule. The design of higher-order mode (HOM) waveguide damping, the simulations of the Lorenz force detuning, and the prototype of on-cell damping are presented.
Date: May 1, 2009
Creator: Haipeng Wang, Guangfeng Cheng, Gianluigi Ciovati, Peter Kneisel, Robert Rimmer, Kai Tian, Larry Turlington, Alireza Nassiri, Geoff Waldschmidt
Partner: UNT Libraries Government Documents Department

Design and Prototype Progress toward a Superconducting Crab Cavity Cryomodule for the APS

Description: A squashed, elliptical supercondconducting (SC) cavity with waveguide dampers on the beam pipes has currently been chosen as the baseline design [1] for the Short Pulse X-ray (SPX) project at the Advanced Photon Source (APS). An alternate cavity design, with a waveguide damper located directly on the cavity cell for improved damping characteristics, has also been designed and cold-tested with promising results. In either case, eight cavities would be operated CW in a single cryomodule at 2K to produce an electron bunch chirp of 4MV at a frequency of 2.815 GHz. Detailed analysis of multipactoring (MP), Lorentz force detuning (LFD), and the thermal properties of the baseline design has led to an engineering specification of the basic parameters of the cryomodule.
Date: May 1, 2010
Creator: Haipeng Wang, Guangfeng Cheng, Gianluigi Ciovati, James Henry, Peter Kneisel, Robert Rimmer, Gary Slack, Larry Turlington, Geoff waldschmidt, Alireza Nassiri
Partner: UNT Libraries Government Documents Department

Fabrication and characterization of submicron polymer waveguides by micro-transfer molding

Description: Various methods exist for fabrication of micron and submicron sized waveguide structures. However, most of them include expensive and time consuming semiconductor fabrication techniques. An economical method for fabricating waveguide structures is introduced and demonstrated in this thesis. This method is established based on previously well-developed photonic crystal fabrication method called two-polymer microtransfer molding. The waveguide in this work functions by a coupler structure that diffracts the incident light into submicron polymer rods. The light is then guided through the rods. Characterization is done by collecting the light that has been guided through the waveguide and exits the end of these submicron polymer bars. The coupling and waveguiding capabilities are demonstrated using two light sources, a laser and white light.
Date: December 15, 2009
Creator: Wu, Te-Wei
Partner: UNT Libraries Government Documents Department

Absorber Materials at Room and Cryogenic Temperatures

Description: We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.
Date: September 1, 2011
Creator: F. Marhauser, T.S. Elliott, A.T. Wu, E.P. Chojnacki, E. Savrun
Partner: UNT Libraries Government Documents Department

First Considerations Concerning an Optimized Cavity Design for the Main Linac of BERLinPro

Description: The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW linac technology and expertise required to drive next-generation Energy Recovery Linacs. Strongly HOM-damped multicell 1.3 GHz cavities are required for the main linac. The optimization of the cavities presented here is primarily based on the CEBAF 1.5 GHz 5-cell high-current cavity design, including HOM waveguide couplers. The cavity was scaled to 1.3 GHz and extended to 7 cells. Modifications to the end group design have also been studied. An effort was also made to reduce the ratio Epk/Eacc while still permitting HOMs to propagate.
Date: September 1, 2011
Creator: B. Riemann, T. Weis, W. Anders, J. Knobloch, A. Neumann, H.-W. Glock, C. Potratz, U. van Rienen, F. Marhauser
Partner: UNT Libraries Government Documents Department

Compact Couplers for Photonic Crystal Laser-Driven Accelerator Structures

Description: Photonic crystal waveguides are promising candidates for laser-driven accelerator structures because of their ability to confine a speed-of-light mode in an all-dielectric structure. Because of the difference between the group velocity of the waveguide mode and the particle bunch velocity, fields must be coupled into the accelerating waveguide at frequent intervals. Therefore efficient, compact couplers are critical to overall accelerator efficiency. We present designs and simulations of high-efficiency coupling to the accelerating mode in a three-dimensional photonic crystal waveguide from a waveguide adjoining it at 90{sup o}. We discuss details of the computation and the resulting transmission. We include some background on the accelerator structure and photonic crystal-based optical acceleration in general.
Date: July 2, 2012
Creator: Cowan, Benjamin; /Tech-X, Boulder; Lin, M.C.; /Tech-X, Boulder; Schwartz, Brian; /Tech-X, Boulder et al.
Partner: UNT Libraries Government Documents Department

The CEBAF Cavity Cryostat

Description: The modular design of the linac cryostat system based on a cavity-pair is presented.Description of the cryogenic module consisting of four cavity-pairs is included.The methods of making a cavity-pair hermetic during cryostat assembly, introducing the waveguides, supporting the helium vessels and introducing instrumentation are presented.Also included are the methods of tuning the cavities, aligning them to exterior references and connecting cryogenic fluid circuits to adjacent modules and transfer lines.
Date: June 1, 1986
Creator: Biallas, George
Partner: UNT Libraries Government Documents Department

Multi-MW K-Band 7th Harmonic Multiplier for High-Gradient Accelerator R&D

Description: A preliminary design and current status are presented for a two-cavity 7th harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power in K-band using as its RF driver an XK-5 S-band klystron (2.856 GHz). The multiplier is to be built with a TE{sub 111} rotating mode input cavity and interchangeable output cavities, a principal example being a TE{sub 711} rotating mode cavity running at 20 GHz. The design that is described uses a 250 kV, 20 A injected laminar electron beam. With 8.5 MW of S-band drive power, 4.4 MW of 20-GHz output power is predicted. The design uses a gun, magnetic coils, and beam collector from an existing waveguide 7th harmonic multiplier. The gun has been re-conditioned and the desired operating parameters have been achieved.
Date: May 1, 2009
Creator: Solyak, N.A.; Yakovlev, V.P.; /Omega-P, New Haven /Fermilab; Hirschfield, J.L.; /Omega-P, New Haven /Yale U.; Kazakevich, G.M. et al.
Partner: UNT Libraries Government Documents Department

An Optimized Input Waveguide for the CEBAF Superconducting Linac Cavity

Description: A thermally optimized input waveguide for the CEBAF Superconducting Linac Cavity, to operate at 2.0K, has been designed.Calculations leading to thermal optimization including conduction, specularly reflected radiation and RF power dissipation are presented.An economic comparison between a thermal intercept and continuous counter flow cooling has been made.Calculations and techniques for reducing specularly reflected radiation are discussed.
Date: October 1, 1986
Creator: Biallas, George & Brindza, Paul
Partner: UNT Libraries Government Documents Department