WorldWideScience

Sample records for subharmonic cavity design

  1. Subharmonic generation, chaos, and subharmonic resurrection in an acoustically driven fluid-filled cavity.

    Cantrell, John H; Adler, Laszlo; Yost, William T

    2015-02-01

    Traveling wave solutions of the nonlinear acoustic wave equation are obtained for the fundamental and second harmonic resonances of a fluid-filled cavity. The solutions lead to the development of a non-autonomous toy model for cavity oscillations. Application of the Melnikov method to the model equation predicts homoclinic bifurcation of the Smale horseshoe type leading to a cascade of period doublings with increasing drive displacement amplitude culminating in chaos. The threshold value of the drive displacement amplitude at tangency is obtained in terms of the acoustic drive frequency and fluid attenuation coefficient. The model prediction of subharmonic generation leading to chaos is validated from acousto-optic diffraction measurements in a water-filled cavity using a 5 MHz acoustic drive frequency and from the measured frequency spectrum in the bifurcation cascade regime. The calculated resonant threshold amplitude of 0.2 nm for tangency is consistent with values estimated for the experimental set-up. Experimental evidence for the appearance of a stable subharmonic beyond chaos is reported.

  2. Application of subharmonics for active sound design of electric vehicles.

    Gwak, Doo Young; Yoon, Kiseop; Seong, Yeolwan; Lee, Soogab

    2014-12-01

    The powertrain of electric vehicles generates an unfamiliar acoustical environment for customers. This paper seeks optimal interior sound for electric vehicles based on psychoacoustic knowledge and musical harmonic theory. The concept of inserting a virtual sound, which consists of the subharmonics of an existing high-frequency component, is suggested to improve sound quality. Subjective evaluation results indicate that the impression of interior sound can be enhanced in this manner. Increased appeal is achieved through two designed stimuli, which proves the effectiveness of the method proposed.

  3. Entanglement characteristics of subharmonic modes reflected from a cavity for type-II second-harmonic generation

    Zhai Zehui; Li Yongming; Gao Jiangrui

    2004-01-01

    Quantum fluctuation and quantum entanglement of the pump fields reflected from an optical cavity for type-II second-harmonic generation are theoretically analyzed. The correlation spectra of quadrature components between the reflected subharmonic fields are interpreted in terms of pump parameter, intracavity losses, and normalized frequency. High correlation of both amplitude and phase quadratures can be accessed in a triple resonant cavity before the pitchfork bifurcation occurs. The two reflected subharmonic fields are in an entangled state with quantum correlation of phase quadratures and anticorrelation of amplitude quadratures. The proposed system can be exploited as a source for generating entangled states of continuous variables

  4. Cavity design programs

    Nelson, E.M.

    1996-01-01

    Numerous computer programs are available to help accelerator physicists and engineers model and design accelerator cavities and other microwave components. This article discusses the problems these programs solve and the principles upon which these programs are based. Some examples of how these programs are used in the design of accelerator cavities are also given

  5. Design of a ×4 subharmonic sub-millimeter wave diode mixer, based on an analytic expression for small-signal conversion admittance parameters

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Krozer, Viktor

    2013-01-01

    Instead of using frequency multipliers before a fundamental mixer, subharmonic mixers can be used. In order to develop novel subharmonic mixer architectures it is necessary to know the exact signal phase at the nonlinear element. The purpose of this paper is to generalize the description of the s....... With an RF frequency of 640 GHz, this design achieves a conversion gain of −13.5 dB with a LO-power of only −2.5 dBm....

  6. Subharmonics, Chaos, and Beyond

    Adler, Laszlo; Yost, William T.; Cantrell, John H.

    2011-01-01

    While studying finite amplitude ultrasonic wave resonance in a one dimensional liquid-filled cavity, which is formed by a narrow band transducer and a plane reflector, subharmonics of the driver's frequency were observed in addition to the expected harmonic structure. Subsequently it was realized that the system was one of the many examples where parametric resonance takes place and in which the observed subharmonics are parametrically generated. Parametric resonance occurs in any physical system which has a periodically modulated natural frequency. The generation mechanism also requires a sufficiently high threshold value of the driving amplitude so that the system becomes increasingly nonlinear in response. The nonlinear features were recently investigated and are the objective of this presentation. An ultrasonic interferometer with optical precision was built. The transducers were compressional undamped quartz and Lithium Niobate crystals ranging from 1-10 Mhz, and driven by a high power amplifier. Both an optical diffraction system and a receive transducer attached to an aligned reflector with lapped flat and parallel surfaces were used to observe the generated frequency components in the cavity.

  7. Design of rf conditioner cavities

    Govil, R.; Rimmer, R.A.; Sessler, A.; Kirk, H.G.

    1992-06-01

    Theoretical studies are made of radio frequency structures which can be used to condition electron beams so as to greatly reduce the stringent emittance requirements for successful lasing in a free-electron laser. The basic strategy of conditioning calls for modulating an electron beam in the transverse dimension, by a periodic focusing channel, while it traverses a series of rf cavities, each operating in a TM 210 mode. In this paper, we analyze the cavities both analytically and numerically (using MAFIA simulations). We find that when cylindrical symmetry is broken the coupling impedance can be greatly enhanced. We present results showing various performance characteristics as a function of cavity parameters, as well as possible designs for conditioning cavities

  8. Computer codes for RF cavity design

    Ko, K.

    1992-08-01

    In RF cavity design, numerical modeling is assuming an increasingly important role with the help of sophisticated computer codes and powerful yet affordable computers. A description of the cavity codes in use in the accelerator community has been given previously. The present paper will address the latest developments and discuss their applications to cavity toning and matching problems

  9. Computer codes for RF cavity design

    Ko, K.

    1992-01-01

    In RF cavity design, numerical modeling is assuming an increasingly important role with the help of sophisticated computer codes and powerful yet affordable computers. A description of the cavity codes in use in the accelerator community has been given previously. The present paper will address the latest developments and discuss their applications to cavity tuning and matching problems. (Author) 8 refs., 10 figs

  10. Design of 340 GHz 2× and 4× Sub-Harmonic Mixers Using Schottky Barrier Diodes in Silicon-Based Technology

    Chao Liu

    2015-05-01

    Full Text Available This paper presents the design of terahertz 2× and 4× sub-harmonic down-mixers using Schottky Barrier Diodes fabricated in standard 0.13 μm SiGe BiCMOS technology. The 340 GHz sub-harmonic mixers (SHMs are designed based on anti-parallel-diode-pairs (APDPs. With the 2nd and 4th harmonic, local oscillator (LO frequencies of 170 GHz and 85 GHz are used to pump the two 340 GHz SHMs. With LO power of 7 dBm, the 2× SHM exhibits a conversion loss of 34.5–37 dB in the lower band (320–340 GHz and 35.5–41 dB in the upper band (340–360 GHz; with LO power of 9 dBm, the 4× SHM exhibits a conversion loss of 39–43 dB in the lower band (320–340 GHz and 40–48 dB in the upper band (340–360 GHz. The measured input 1-dB conversion gain compression point for the 2× and 4× SHMs are −8 dBm and −10 dBm at 325 GHz, respectively. The simulated LO-IF (intermediate frequency isolation of the 2× SHM is 21.5 dB, and the measured LO-IF isolation of the 4× SHM is 32 dB. The chip areas of the 2× and 4× SHMs are 330 μm × 580 μm and 550 μm × 610 μm, respectively, including the testing pads.

  11. Electromagnetic Design of a Radiofrequency Cavity

    Montoya Soto, G. R.; Duarte Galvan, Carlos; Monzon, Ildefonso Leon; Podesta Lerma, Pedro Luis manuel; Valerio-Lizarraga, C. A.

    2017-10-01

    Electromagnetic and mechanical studies have been performed with the aim of build a RF cavity in the S-Band (2998 MHz), the design takes into consideration the relativistic change in the electron velocity through the acceleration cavity. Four cavity cases were considered at different input energies, 50 KeV, 100 KeV, 150 KeV, with output energies of 350 KeV, the designs show good acceleration efficiency and beam coherence comparable to the one created in the cathode.

  12. Design of half-reentrant SRF cavities

    Meidlinger, M.; Grimm, T.L.; Hartung, W.

    2006-01-01

    The shape of a TeSLA inner cell can be improved to lower the peak surface magnetic field at the expense of a higher peak surface electric field by making the cell reentrant. Such a single-cell cavity was designed and tested at Cornell, setting a world record accelerating gradient [V. Shemelin et al., An optimized shape cavity for TESLA: concept and fabrication, 11th Workshop on RF Superconductivity, Travemuende, Germany, September 8-12, 2003; R. Geng, H. Padamsee, Reentrant cavity and first test result, Pushing the Limits of RF Superconductivity Workshop, Argonne National Laboratory, September 22-24, 2004]. However, the disadvantage to a cavity is that liquids become trapped in the reentrant portion when it is vertically hung during high pressure rinsing. While this was overcome for Cornell's single-cell cavity by flipping it several times between high pressure rinse cycles, this may not be feasible for a multi-cell cavity. One solution to this problem is to make the cavity reentrant on only one side, leaving the opposite wall angle at six degrees for fluid drainage. This idea was first presented in 2004 [T.L. Grimm et al., IEEE Transactions on Applied Superconductivity 15(6) (2005) 2393]. Preliminary designs of two new half-reentrant (HR) inner cells have since been completed, one at a high cell-to-cell coupling of 2.1% (high-k cc HR) and the other at 1.5% (low-k cc HR). The parameters of a HR cavity are comparable to a fully reentrant cavity, with the added benefit that a HR cavity can be easily cleaned with current technology

  13. Subharmonic buncher for the Los Alamos free-electron laser oscillator experiment

    Fraser, J.S.

    1983-01-01

    A high efficiency free-electron laser oscillator experiment is being constructed at Los Alamos National Laboratory. A buncher system has been designed to deliver 30-ps, 5-nC electron bunches to a 20-MeV standing-wave linac at the 60th subharmonic of the 1300-MHz accelerator frequency. The first 108.3-MHz buncher cavity accepts a 5-ns, 5-A peak current pulse from a triode gun. Following a 120-cm drift space, a second 108.3-MHz cavity is used, primarily to enhance the bunching of the trailing half of the bunch. A 1300-MHz cavity with 20-cm drift spaces at the each end completes the beamline components. The bunching process continues into the linac's first three accelerating cells. Two thin iron-shielded lenses and several large-diameter solenoids provide axial magnetic fields for radial focusing

  14. Sub-harmonic bunching with the AGOR cyclotron

    Brandenburg, S; Roobol, LP; Stokroos, M; Marti, F

    2001-01-01

    A quasi-single gap buncher with saw-tooth voltage has been designed and is currently being built at the KVI. It operates at a sub-harmonic of the RF frequency and has a duty cycle of 80% at 15 MHz. We report on the design of the new buncher, and on results of tests with our sinusoidal buncher to

  15. Tuner Design for PEFP Superconducting RF Cavities

    Tang, Yazhe; An, Sun; Zhang, Liping; Cho, Yong Sub

    2009-01-01

    A superconducting radio frequency (SRF) cavity will be used to accelerate a proton beam after 100 MeV at 700 MHz in a linac of the Proton Engineering Frontier Project (PEFP) and its extended project. In order to control the SRF cavity's operating frequency at a low temperature, a new tuner has been developed for the PEFP SRF cavities. Each PEFP superconducting RF cavity has one tuner to match the cavity resonance frequency with the desired accelerator operating frequency; or to detune a cavity frequency a few bandwidths away from a resonance, so that the beam will not excite the fundamental mode, when the cavity is not being used for an acceleration. The PEFP cavity tuning is achieved by varying the total length of the cavity. The length of the cavity is controlled differentially by tuner acting with respect to the cavity body. The PEFP tuner is attached to the helium vessel and drives the cavity Field Probe (FP) side to change the frequency of the cavity

  16. L-Band Polarimetric Correlation Radiometer with Subharmonic Sampling

    Rotbøll, Jesper; Søbjærg, Sten Schmidl; Skou, Niels

    2001-01-01

    A novel L-band radiometer trading analog complexity for digital ditto has been designed and built. It is a fully polarimetric radiometer of the correlation type and it is based on the sub-harmonic sampling principle in which the L-band signal is directly sampled by a fast A to D converter...

  17. A novel L-band polarimetric radiometer featuring subharmonic sampling

    Rotbøll, J.; Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D...

  18. MECHANICAL CAVITY DESIGN FOR 100MV UPGRADE CRYOMODULE

    K.M. Wilson; G. Ciovati; E. F. Daly; J. Henry; R. Hicks; J. Hogan; D. Machie; P. Kneisel; C. Reece; J. Sekutowicz; T. Whitlatch

    2003-01-01

    To achieve up to 6 GeV, each cryomodule in the CEBAF accelerator currently provides about 30 MV of acceleration. To raise the accelerator energy to 12 GeV, ten additional cryomodules capable of providing over 100 MV of acceleration are required. A prototype of the 100 MV cryomodule has been designed, is presently under construction, and will be completed in 2004. This prototype cryomodule comprises two new cavity designs, four cavities of the low loss design and four cavities of the high gradient design. Although the cavity shapes were designed for their RF properties, the mechanical implications must be considered. In addition to the new cavity shapes, changes have also been made to the cavity end dish assemblies, weld joints, and stiffening rings. This paper will present the results of the stress and vibration analyses used for designing the cryomodule

  19. Estimation of Tumor Angiogenesis With Contrast Enhanced Subharmonic Ultrasound Imaging

    Forsberg, Flemming

    2001-01-01

    ...) and receiving at the subharmonic (f0) . Because of no subharmonic generation in tissue and significant subharmonic scattering from some new contrast agents SHI has the potential to detect slow, small volume blood flow associated with tumor...

  20. Design of 325 MHz spoke cavity

    Sha Peng; Huang Hong; Dai Jianping; Zu Guoquan; Li Han

    2012-01-01

    Spoke cavity can be used in the low-energy section of the proton accelerator. It has many significant advantages: compact structure, high value of R/Q, etc. The ADS (Accelerator Driven System) project will adopt many spoke cavities with different β values. Therefore, IHEP has began the research of β=0.14, 325 MHz spoke cavity. In this pa per, the dimensions, RF performances and mechanical properties of it are studied. (authors)

  1. Control System Design for Automatic Cavity Tuning Machines

    Carcagno, R.; Khabiboulline, T.; Kotelnikov, S.; Makulski, A.; Nehring, R.; Nogiec, J.; Ross, M.; Schappert, W.; /Fermilab; Goessel, A.; Iversen, J.; Klinke, D.; /DESY

    2009-05-01

    A series of four automatic tuning machines for 9-cell TESLA-type cavities are being developed and fabricated in a collaborative effort among DESY, FNAL, and KEK. These machines are intended to support high-throughput cavity fabrication for construction of large SRF-based accelerator projects. Two of these machines will be delivered to cavity vendors for the tuning of XFEL cavities. The control system for these machines must support a high level of automation adequate for industrial use by non-experts operators. This paper describes the control system hardware and software design for these machines.

  2. Control System Design for Automatic Cavity Tuning Machines

    Carcagno, R.; Khabiboulline, T.; Kotelnikov, S.; Makulski, A.; Nehring, R.; Nogiec, J.; Ross, M.; Schappert, W.; Goessel, A.; Iversen, J.; Klinke, D.

    2009-01-01

    A series of four automatic tuning machines for 9-cell TESLA-type cavities are being developed and fabricated in a collaborative effort among DESY, FNAL, and KEK. These machines are intended to support high-throughput cavity fabrication for construction of large SRF-based accelerator projects. Two of these machines will be delivered to cavity vendors for the tuning of XFEL cavities. The control system for these machines must support a high level of automation adequate for industrial use by non-experts operators. This paper describes the control system hardware and software design for these machines.

  3. Design and Optimization of Thermophotovoltaic System Cavity with Mirrors

    Tian Zhou

    2016-09-01

    Full Text Available Thermophotovoltaic (TPV systems can convert radiant energy into electrical power. Here we explore the design of the TPV system cavity, which houses the emitter and the photovoltaic (PV cells. Mirrors are utilized in the cavity to modify the spatial and spectral distribution within. After discussing the basic concentric tubular design, two novel cavity configurations are put forward and parametrically studied. The investigated variables include the shape, number, and placement of the mirrors. The optimization objectives are the optimized efficiency and the extended range of application of the TPV system. Through numerical simulations, the relationship between the design parameters and the objectives are revealed. The results show that careful design of the cavity configuration can markedly enhance the performance of the TPV system.

  4. Design of the Advanced Virgo non-degenerate recycling cavities

    Granata, M; Barsuglia, M; Flaminio, R; Freise, A; Hild, S; Marque, J

    2010-01-01

    Advanced Virgo is the project to upgrade the interferometric gravitational wave detector Virgo, and it foresees the implementation of power and signal non-degenerate recycling cavities. Such cavities suppress the build-up of high order modes of the resonating sidebands, with some advantage for the commissioning of the detector and the build-up of the gravitational signal. Here we present the baseline design of the Advanced Virgo non-degenerate recycling cavities, giving some preliminary results of simulations about the tolerances of this design to astigmatism, mirror figure errors and thermal lensing.

  5. Superconducting radio frequency cavities: design, development and results

    Prakash, P.N.; Mistri, K.K.; Sonti, S.S.K.; Sacharias, J.; Raiand, A.; Kanjilal, D.

    2013-01-01

    In recent years, the development of superconducting niobium cavities has evoked a lot of interest among the accelerator physics community of India. Many laboratories are planning to develop superconducting niobium cavities for new accelerators and applications. Inter-University Accelerator Centre (IUAC) has been engaged in the indigenous development of niobium resonators for over a decade. During this period, several quarter wave resonators have been successfully built, tested and installed in the superconducting linac at IUAC. A new niobium low beta resonator for the High Current Injector (HCI) project has been designed, prototyped and tested. In addition to the in-house projects, IUAC is nearing completion of two niobium single spoke resonators (SSR1) for Fermi Lab, USA. Under the Indian Institutions and Fermi Lab Collaboration (IIFC), Raja Ramanna Centre for Advanced Technology, Indore and Inter-University Accelerator Centre have jointly developed TESLA-type 1.3 GHz single cell cavities which have achieved very high accelerating gradients. Buoyed by the success of this work, a 5-cell 1.3 GHz cavity with simple end tubes has been successfully built. This cavity is presently at Fermi Lab for 2 K tests. Recently, a 650 MHz, β=0.9 single cell cavity has also been successfully completed and is ready for cold tests. There are plans to develop a 650 MHz, β=0.6 single cell cavity in collaboration with VECC, Kolkata. This paper presents the status of the niobium cavities developed at Inter-University Accelerator Centre. (author)

  6. Design of 118 MHz twelfth harmonic cavity of APS PAR

    Kang, Y.W.; Kustom, R.L.; Bridges, J.F.

    1992-01-01

    Two radio frequency (RF) cavities are needed in the Positron Accumulator Ring (PAR) of the Advanced Photon Source. One is for the first harmonic frequency at 9.8 MHz, and the other is for the twelfth harmonic frequency at 118 MHz. This note reports on the design of the 118 MHz RF cavity. Computer models are used to find the mode frequencies, impedances, Q-factors, and field distributions in the cavity. The computer codes MAFIA, URMEL, and URMEL-T are useful tools which model and simulate the resonance characteristics of a cavity. These codes employ the finite difference method to solve Maxwell's equations. MAFIA is a three-dimensional problem solver and uses square patches to approximate the inner surface of a cavity. URMEL and URMEL-T are two-dimensional problem solvers and use rectangular and triangular meshes, respectively. URMEL-T and MAFIA can handle problems with arbitrary dielectric materials located inside the boundary. The cavity employs a circularly cylindrical ceramic window to limit the vacuum to the beam pipe. The ceramic window used in the modeling will have a wall thickness of 0.9 cm. This wall thickness is not negligible in determining the resonant frequencies of the cavity. In the following, results of two- and three-dimensional modeling of the cavities using the URMEL-T and MAFIA codes are reported

  7. Design study of 'HIBLIC-I' reactor cavity

    Fujiie, Y.

    1984-01-01

    A preliminary conceptual design of a reactor cavity for HIBLIC-1, a heavy ion fusion reactor system, was carried out. Design efforts have been concentrated mainly on the feasibility study of the physical scenario adopted and also on the system integration of the structures and components into a compact reactor cavity. The design features of the reactor are a compact reactor cavity, maximum coolant temperature up to 500 deg C, the protection of the sacrificial wall and cavity wall from radiation, the protection of the sacrificial wall from the pressure transient due to rapid heating, the selection of a ferritic steel HT-9 as the structural material and impurity control, and tritium breeding and recovery. The purpose of this paper is to describe the outline of the reactor cavity design of HIBLIC-1. The objectives of the preliminary conceptual design were to propose the idea and concept in order to constitute the physical scenario without contradiction and to find out the critical and fundamental problems to be studied in future. The cavity configuration and dynamics, tritium breeding and radiation damage, the behavior of a structural material in liquid lithium and tritium recovery are reported. (Kako, I.)

  8. Physics design of APT linac with normal conducting rf cavities

    Nath, S.; Billen, J.H.; Stovall, J.E.; Takeda, Harunori; Young, L.M.

    1996-01-01

    The accelerator based production of tritium calls for a high-power, cw proton linac. Previous designs for such a linac use a radiofrequency quadrupole (RFQ), followed by a drift-tube linac (DTL) to an intermediate energy and a coupled-cavity linc (CCL) to the final energy. The Los Alamos design uses a high-energy (6.7 MeV) RFQ followed by the newly developed coupled-cavity drift-tube linac (CCDTL) and a CCL. This design accommodates external electromagnetic quadrupole lenses which provide a strong uniform focusing lattice from the end of the RFQ to the end of the CCL. The cell lengths in linacs of traditional design are typically graded as a function of particle velocity. By making groups of cells symmetric in both the CCDTL and CCL, the cavity design as well as mechanical design and fabrication is simplified without compromising the performance. At higher energies, there are some advantages of using superconducting rf cavities. Currently, such schemes are under vigorous study. This paper describes the linac design based on normal conducting cavities and presents simulation results

  9. R.F. cavity design for the NSLS

    Batchelor, K.; Galayda, J.; Hawrylak, R.

    1981-01-01

    The r.f cavity design for the Booster, vuv ring and x-ray ring of the NSLS is described together with the mechanical design of tuners, coupling and monitoring loops and the temperature control systems. The results of higher order mode measurements as compared with Superfish calculations are also presented

  10. Design of large aperture 500 MHz 5-cell superconducting cavity

    Wei Yelong; Feng Ziqiang; Lu Changwang; Yu Haibo; Liu Jianfei; Hou Hongtao; Ma Zhenyu; Mao Dongqing

    2012-01-01

    With the potential application of Energy Recovery Linac (ERL), the superconducting (SC) cavities were developed to deliver much higher current than before. Nowadays, the current of the international SC accelerator designed has already exceeded 100 mA. This paper presents the design of a new 500 MHz 5-cell SC cavity (SINAP 5-cell cavity), in which the parameters r/Q= 515.5 Ω of the fundamental mode and the geometry factor G=275.8 are under an acceptable Radio Frequency (RF) field level. (B peak /E acc =4.31 mT/MV/m and E peak /E acc =2.48). This design employs a larger beam pipe to propagate the Higher Order Modes (HOMs) out of the cavity and increases the damping efficiently for the dangerous HOMs. By simulation technique, it has been found that almost all the dangerous HOMs (including TE 111 , TM 110 , and TM 011 ) can be propagated into the beam pipe and are absorbed by ferrite absorbers, when the beam pile is enlarged. Finally, the loss factor for the new 5-cell cavity is also calculated. (authors)

  11. Mechanical Design and Fabrication Studies for SPL Superconducting RF Cavities

    Atieh, S; Aviles Santillana, I; Capatina, O; Renaglia, T; Tardy, T; Valverde Alonso, N; Weingarten, W

    2011-01-01

    CERN’s R&D programme on the Superconducting Proton Linac’s (SPL) superconducting radio frequency (SRF) elliptical cavities made from niobium sheets explores new mechanical design and consequently new fabrication methods, where several opportunities for improved optimization were identified. A stainless steel helium vessel is under design rather than a titanium helium vessel using an integrated brazed transition between Nb and the SS helium vessel. Different design and fabrication aspects were proposed and the results are discussed hereafter.

  12. Meeting to discuss laser cavity design for photon linear collider ...

    linear collider – Daresbury, UK, 10 January 2006. ALEXANDER JOHN FINCH ... On 10 January 2006, a meeting to discuss laser cavity design for the photon linear collider was held at the Daresbury .... important to continue making contact with people in fields outside the accelerator community. Few experts at this meeting ...

  13. Cavity design and beam simulations for the APS rf gun

    Borland, M.

    1991-01-01

    An earlier note discussed the preliminary design of the 1-1/2 cell RF cavity for the APS RF gun. This note describes the final design, including cavity properties and simulation results from the program rf gun. The basic idea for the new design was that the successful SSRL design could be improved upon by reducing fields that had nonlinear dependence on radius. As discussed previously, this would reduce the emittance and produce tighter momentum and time distributions. In addition, it was desirable to increase the fields in the first half-cell relative to the fields in the second half-cell, in order to allow more rapid initial acceleration, which would reduce the effects of space charge. Both of these goals were accomplished in the new design

  14. Design and analysis of PCRV core cavity closure

    Lee, T.T.; Schwartz, A.A.; Koopman, D.C.A.

    1980-05-01

    Design requirements and considerations for a core cavity closure which led to the choice of a concrete closure with a toggle hold-down as the design for the Gas-Cooled Fast Breeder Reactor (GCFR) plant are discussed. A procedure for preliminary stress analysis of the closure by means of a three-dimensional finite element method is described. A limited parametric study using this procedure indicates the adequacy of the present closure design and the significance of radial compression developed as a result of inclined support reaction

  15. Design Topics for Superconducting RF Cavities and Ancillaries

    Padamsee, H

    2014-01-01

    RF superconductivity has become a major subfield of accelerator science. There has been an explosion in the number of accelerator applications and in the number of laboratories engaged. The first lecture at this meeting of the CAS presented a review of fundamental design principles to develop cavity geometries to accelerate velocity-of-light particles (β = v/c ~ 1), moving on to the corresponding design principles for medium-velocity (medium-β) and low-velocity (low-β) structures. The lecture included mechanical design topics. The second lecture dealt with input couplers, higher-order mode extraction couplers with absorbers, and tuners of both the slow and fast varieties

  16. Design Topics for Superconducting RF Cavities and Ancillaries

    Padamsee, H [Cornell University, CLASSE (United States)

    2014-07-01

    RF superconductivity has become a major subfield of accelerator science. There has been an explosion in the number of accelerator applications and in the number of laboratories engaged. The first lecture at this meeting of the CAS presented a review of fundamental design principles to develop cavity geometries to accelerate velocity-of-light particles (β = v/c ~ 1), moving on to the corresponding design principles for medium-velocity (medium-β) and low-velocity (low-β) structures. The lecture included mechanical design topics. The second lecture dealt with input couplers, higher-order mode extraction couplers with absorbers, and tuners of both the slow and fast varieties.

  17. Design of a cavity heat pipe receiver experiment

    Schneider, Michael G.; Brege, Mark H.; Greenlee, William J.

    1992-01-01

    A cavity heat pipe experiment has been designed to test the critical issues involved with incorporating thermal energy storage canisters into a heat pipe. The experiment is a replication of the operation of a heat receiver for a Brayton solar dynamic power cycle. The heat receiver is composed of a cylindrical receptor surface and an annular heat pipe with thermal energy storage canisters and gaseous working fluid heat exchanger tubes surrounding it. Hardware for the cavity heat pipe experiment will consist of a sector of the heat pipe, complete with gas tube and thermal energy storage canisters. Thermal cycling tests will be performed on the heat pipe sector to simulate the normal energy charge/discharge cycle of the receiver in a spacecraft application.

  18. Novel Ion Trap Design for Strong Ion-Cavity Coupling

    Alejandro Márquez Seco

    2016-04-01

    Full Text Available We present a novel ion trap design which facilitates the integration of an optical fiber cavity into the trap structure. The optical fibers are confined inside hollow electrodes in such a way that tight shielding and free movement of the fibers are simultaneously achievable. The latter enables in situ optimization of the overlap between the trapped ions and the cavity field. Through numerical simulations, we systematically analyze the effects of the electrode geometry on the trapping characteristics such as trap depths, secular frequencies and the optical access angle. Additionally, we simulate the effects of the presence of the fibers and confirm the robustness of the trapping potential. Based on these simulations and other technical considerations, we devise a practical trap configuration that isviable to achieve strong coupling of a single ion.

  19. Subharmonic projections for a quantum Markov semigroup

    Fagnola, Franco; Rebolledo, Rolando

    2002-01-01

    This article introduces a concept of subharmonic projections for a quantum Markov semigroup, in view of characterizing the support projection of a stationary state in terms of the semigroup generator. These results, together with those of our previous article [J. Math. Phys. 42, 1296 (2001)], lead to a method for proving the existence of faithful stationary states. This is often crucial in the analysis of ergodic properties of quantum Markov semigroups. The method is illustrated by applications to physical models

  20. Mechanical design and fabrication of power feed cavity test setup

    Ghodke, S.R.; Dhavle, A.S.; Sharma, Vijay; Sarkar, Shreya; Kumar, Mahendra; Nayak, Susanta; Barnwal, Rajesh; Jayaprakash, D.; Mondal, J.; Nimje, V.T.; Mittal, K.C.; Gantayet, L.M.

    2013-01-01

    Power feed cavity set up consists of nine number of accelerating cavity and eight numbers of coupling cavity for testing of power feed cavity with coupling flange for 2856 MHz S band standing wave coupled cavity linac. When we are assembling the cavity and applying the pressure, its resonance frequency changes with applied pressure/load. After some critical pressure/load frequency change becomes negligible or zero. This set up will be used to find out assembly performance of power feed cavity and its coupler. Top four cavity or eight half cells as well as bottom four cavity or eight half cells will be brazed separately. Power feed cavity will be sandwiched between this two brazed cavity assemblies. This paper discuss about linear motion bush, linear motion rod, load cell, hydraulic actuator, power pack, stepper motor PLC control, jig boring, alignment, tolerances and assembly procedure for this test setup. (author)

  1. Optimization of Helium Vessel Design for ILC Cavities

    Fratangelo, Enrico [Univ. of Pisa (Italy)

    2009-01-01

    certify the compliance of the Helium vessel and the cavity to the ASME code standard. After briefly recalling to the main contents of the the ASME Code (Sections II and Vlll - Division ll), the procedure used for finding all relevant stresses and comparing the obtained results with the maximum values allowed are explained. This part also includes the buckling verification of the cavity. In Chapter 5 the manufacturing process of the cavity end-caps, whose function is to link the Helium vessel with the cavity, is studied. The present configuration of the dies is described and the manufacturing process is simulated in order to explain the origin of some defects fol.llld on real parts. Finally a new design of the dies is proposed and the resulting deformed piece is compared with the design requirements. Chapter 6 describes a finite elements analysis to assess the efficiency and the stiffness of the Helium vessel. Furthermore the results of the optimization of the Helium vessel (in order to increase the value of the efficiency) are reported. The same stiffness analysis is used in Chapter 7 for the Blade-Tuner study. After a description of this tuner and of its function, the preliminary analyses done to confirm the results provided by the vendor are described and then its limiting load conditions are found. Chapter 8 shows a study of the resistance of all the welds present in between the cavity and the end-cap and between the end-caps and the He vessel for a smaller superconducting cavity operating at 3.9 GHz. Finally Chapter 9 briefly describes some R&D activities in progress at INFN (Section of Pisa) and Fermilab that could produce significant cost reductions of the Helium vessel design. All the finite elements analyses contained and described in this thesis made possible the certification of the whole superconducting cavity-Helium vessel assembly at Fermilab. Furthermore they gave several useful indications to the Fermilab staff to improve the performance of the Helium

  2. Superconducting Super Collider Laboratory coupled-cavity linac mechanical design

    Starling, W.J.; Cain, T.

    1992-01-01

    A collaboration between the Superconducting Super Collider Laboratory (SSCL) and the Los Alamos National Laboratory (LANL) for the engineering and mechanical design of the SSCL Coupled-Cavity Linac (CCL) has yielded an innovative example of the well known side coupled-cavity type of linear accelerator. The SSCL CCL accelerates an H - beam from 70 MeV to 600 MeV with an rf cavity structure consisting of eight tanks in each of nine modules for a total length of about 112 meters. Magnetically-coupled bridge couplers transfer power from tank to tank within a module. A single rf power input is located at the center bridge coupler of each module. The bridge couplers permit placement along the beam line of combined function focusing/steering electromagnets and diagnostic pods for beam instrumentation. Each tank and bridge coupler is rf frequency stabilized, nominally to 1,283 MHz, by water pumped through integral water passages. Air isolation grooves surround the water passages at each braze joint so that water-to-vacuum interfaces are avoided. Each tank is supported by adjustable spherical bearing rod end struts to permit alignment and accommodate thermal expansion and contraction of the rf structure. Tank struts, electromagnet/diagnostic pod support frames, vacuum manifolds and utilities are all mounted to a girder-and-leg support stand running the full length of the CCL. (Author) tab., fig

  3. Design and test of SX-FEL cavity BPM

    Yuan Renxian; Zhou Weimin; Chen Zhichu; Yu Luyang; Wang Baopen; Leng Yongbin

    2013-01-01

    This paper reports the design and cold test of the cavity beam position monitor (CBPM) for SX-FEL to fulfill the requirement of beam position measurement resolution of less than 1 μm, even 0.1 μm. The CBPM was optimized by using a coupling slot to damp the TM 010 mode in the output signal. The isolation of TM 010 mode is about 117 dB, and the shunt impedance is about 200 Ω@4.65 GHz with the quality factor 80 from MAFIA simulation and test result. A special antenna was designed to load power for reducing excitation of other modes in the cavity. The resulting output power of TM 110 mode was about 90 mV/mm when the source was 6 dBm, and the accomplishable minimum voltage was about 200 μV. The resolution of the CBPM was about 0.1 μm from the linear fitting result based on the cold test. (authors)

  4. Design of 650 MHz, β=0.61, 5-cell SRF cavity and development of single cell niobium cavity

    Seth, Sudeshna; Som, Sumit; Bhattacharyya, Pranab

    2015-01-01

    In India, DAE laboratories and other institutes are now actively involved in research and development activities on SRF cavities and associated technologies for the proposed high current, high energy proton linear accelerators like ISNS/IADS and also for the FERMILAB PIP-II program under Indian institutions-Fermilab collaboration (IIFC). As part of the above activities, VECC, Kolkata, has been involved in the design, analysis and development of a 650 MHz, β=0.61, 5-cell elliptical shape Superconducting RF linac cavity. RF design involves optimization of the geometry to get acceptable values of field enhancement factors (magnetic and electric), R/Q , Geometric factor, coupling factor and field flatness. This paper describes the RF design using 2-D superfish and 3-D CST Microwave studio and multipacting analysis using 2-D Multipac2.1 and 3-D CST Particle Studio. A prototype 1-cell aluminum cavity and a prototype 5-cell copper cavity have been fabricated using die-punch assembly designed for fabrication of elliptical half-cells to check the procedures for forming and to make sure the desired frequency and field flatness could be obtained. RF characterization has been carried out for both the prototypes using Vector Network Analyzer and Bead pull measurement set up.The fabrication of a single-cell niobium cavity has been carried out indigenously and with the help of Electron Beam Welding (EBW) facility at IUAC, New Delhi. CMM measurement and RF characterization of the niobium half cells and full cell cavities have been carried out. This paper describes the development and measurement of prototype cavities and single cell niobium cavity. (author)

  5. Nonlinear Stochastic Analysis of Subharmonic Response of a Shallow Cable

    Zhou, Q.; Stærdahl, Jesper Winther; Nielsen, Søren R.K.

    2007-01-01

    and stochastic subharmonic response is demonstrated upon comparison with a more involved model based on a spatial finite difference discretization of the full nonlinear partial differential equations of the cable. Since the stochastic response quantities are obtained by Monte Carlo simulation, which is extremely...... time-consuming for the finite difference model, most of the results are next based on the reduced model. Under harmonical varying support point motions the stable subharmonic motion consists of a harmonically varying component in the equilibrium plane and a large subharmonic out-of-plane component...... subharmonic response component is also present in the static equilibrium plane. Further, the time variation of the envelope process of the narrow-banded chordwise elongation process tends to enhance chaotic behaviour of the subharmonic response, which is detectable via extreme sensitivity on the initial...

  6. Mechanical design of SXLS [Superconducting X-ray Lithography Source] radio-frequency cavity

    Mortazavi, P.; Sharma, S.; Keane, J.; Thomas, M.

    1989-01-01

    This paper presents the mechanical design of a Radio-Frequency (RF) cavity to be used on a compact storage ring for Superconducting X-ray Lithography Source (SXLS). Various design features of this cavity are discussed, including basic geometrical configuration, structural design, initial and operational tuning, vacuum multipactoring, power window, and damping of higher order modes. A second application of this cavity design for beam life extension in an existing storage ring is also described. 2 refs., 6 figs

  7. Mechanical design of SXLS (Superconducting X-ray Lithography Source) radio-frequency cavity

    Mortazavi, P.; Sharma, S.; Keane, J.; Thomas, M.

    1989-01-01

    This paper presents the mechanical design of a Radio-Frequency (RF) cavity to be used on a compact storage ring for Superconducting X-ray Lithography Source (SXLS). Various design features of this cavity are discussed, including basic geometrical configuration, structural design, initial and operational tuning, vacuum multipactoring, power window, and damping of higher order modes. A second application of this cavity design for beam life extension in an existing storage ring is also described. 2 refs., 6 figs.

  8. CLIC crab cavity design optimisation for maximum luminosity

    Dexter, A.C., E-mail: a.dexter@lancaster.ac.uk [Lancaster University, Lancaster, LA1 4YR (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD (United Kingdom); Burt, G.; Ambattu, P.K. [Lancaster University, Lancaster, LA1 4YR (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD (United Kingdom); Dolgashev, V. [SLAC, Menlo Park, CA 94025 (United States); Jones, R. [University of Manchester, Manchester, M13 9PL (United Kingdom)

    2011-11-21

    The bunch size and crossing angle planned for CERN's compact linear collider CLIC dictate that crab cavities on opposing linacs will be needed to rotate bunches of particles into alignment at the interaction point if the desired luminosity is to be achieved. Wakefield effects, RF phase errors between crab cavities on opposing linacs and unpredictable beam loading can each act to reduce luminosity below that anticipated for bunches colliding in perfect alignment. Unlike acceleration cavities, which are normally optimised for gradient, crab cavities must be optimised primarily for luminosity. Accepting the crab cavity technology choice of a 12 GHz, normal conducting, travelling wave structure as explained in the text, this paper develops an analytical approach to optimise cell number and iris diameter.

  9. Periodic and subharmonic solutions for second order p-Laplacian ...

    Periodic and subharmonic solutions; -Laplacian; difference equations; discrete variational theory. ... Packaging Engineering Institute, Jinan University, Zhuhai 519070, People's Republic of China; College of Mathematics and Information Sciences, Guangzhou University, Guangzhou 510006, People's Republic of China ...

  10. Estimation of Tumor Angiogenesis With Contrast Enhanced Subharmonic Ultrasound Imaging

    Forsberg, Flemming

    2005-01-01

    ...) and receiving at the subharmonic (f0). Hence, the current project proposes to increase the ability of breast ultrasound to differentiate between benign and malignant lesions by combining injection of an ultrasound contrast agent with SHI...

  11. Mechanical Design of a New Injector Cryomodule 2-Cell Cavity at CEBAF

    Cheng, Guangfeng G. [JLAB; Henry, James E. [JLAB; Mammosser, John D. [JLAB; Rimmer, Robert A. [JLAB; Wang, Haipeng [JLAB; Wiseman, Mark A. [JLAB; Yang, Shuo [JLAB

    2013-12-01

    As a part of Jefferson Lab’s 12 GeV upgrade, a new injector superconducting RF cryomodule is required. This unit consists of a 2-cell and 7-cell cavity, with the latter being refurbished from an existing cavity. The new 2-cell cavity requires electromagnetic design and optimization followed by mechanical design analyses. The electromagnetic design is reported elsewhere. This paper aims to present the procedures and conclusions of the analyses on cavity tuning sensitivity, pressure sensitivity, upset condition pressure induced stresses, and structural vibration frequencies. The purposes of such analyses include: 1) provide reference data for cavity tuner design; 2) examine the structural integrity of the cavity; and 3) evaluate the 2-cell cavity’s resistance to microphonics. Design issues such as the location of stiffening rings, effect of tuner stiffness on cavity stress, choice of cavity wall thickness, etc. are investigated by conducting extensive finite element analyses. Progress in fabrication of the 2-cell cavity is also reported.

  12. Subharmonic emissions from microbubbles: effect of the driving pulse shape.

    Biagi, Elena; Breschi, Luca; Vannacci, Enrico; Masotti, Leonardo

    2006-11-01

    The aims of this work are to investigate the response of the ultrasonic contrast agents (UCA) insonified by different arbitrary-shaped pulses at different acoustic pressures and concentration of the contrast agent focusing on subharmonic emission. A transmission setup was developed in order to insonify the contrast agent contained in a measurement chamber. The transmitted ultrasonic signals were generated by an arbitrary wave generator connected to a linear power amplifier able to drive a single-element transducer. The transmitted ultrasonic pulses that passed through the contrast agent-filled chamber were received by a second transducer or a hydrophone aligned with the first one. The radio frequency (RF) signals were acquired by fast echographic multiparameters multi-image novel apparatus (FEMMINA), which is an echographic platform able to acquire ultrasonic signals in a real-time modality. Three sets of ultrasonic signals were devised in order to evaluate subharmonic response of the contrast agent respect with sinusoidal burst signals used as reference pulses. A decreasing up to 30 dB in subharmonic response was detected for a Gaussian-shaped pulse; differences in subharmonic emission up to 21 dB were detected for a composite pulse (two-tone burst) for different acoustic pressures and concentrations. Results from this experimentation demonstrated that the transmitted pulse shape strongly affects subharmonic emission in spite of a second harmonic one. In particular, the smoothness of the initial portion of the shaped pulses can inhibit subharmonic generation from the contrast agents respect with a reference sinusoidal burst signal. It also was shown that subharmonic generation is influenced by the amplitude and the concentration of the contrast agent for each set of the shaped pulses. Subharmonic emissions that derive from a nonlinear mechanism involving nonlinear coupling among different oscillation modes are strongly affected by the shape of the ultrasonic

  13. Design of radio-frequency cavities and Tera-Hertz electron injectors for advanced applications

    Seyedfakhari, Seyedmoein

    2016-06-15

    Design of three accelerator components including a buncher cavity for REGAE, a normal conducting cavity for arrival time stabilization at FLASH and ultra-fast guns for the AXSIS project is presented in this thesis. Using RF cavities caused a revolution in accelerators and made it possible to generate high energy particle beams. In advanced accelerators, cavities are not only used to increase the particle energy but they are also widely used to improve the beam quality and additionally for beam diagnostic purposes. In the present dissertation, such applications are discussed. First, design of a buncher cavity which compresses the bunch at the REGAE facility is presented. The design pursues improving the mode separation of the cavity. The simulation result illustrates that the difference between the operating mode and its adjacent mode has been increased from 2 MHz for the existing cavity to 9.5 MHz for the new design. In the second part, a normal conducting cavity is discussed, which will be used to regulate the arrival time ofthe bunches at FLASH and at the European XFEL. The designed cavity is able to correct the arrival time jitter of ± 150 fs in order to provide femtosecond precision synchronization between the electron beam and the external laser pulses. Thermal, wakefield and multipacting simulations have also been performed for the designed cavity in order to evaluate its operation efficiency. In advanced accelerators however RF cavities should be replaced by novel structures to accelerate the particles in shorter distances using higher operating frequency. To this end, ultra-fast guns are designed which will be discussed in the last part of this work. The designed guns accelerate the electrons from their rest mass up to 2 MeV using a single cycle THz signal with a total energy of 2 mJ.

  14. Design of radio-frequency cavities and Tera-Hertz electron injectors for advanced applications

    Seyedfakhari, Seyedmoein

    2016-06-01

    Design of three accelerator components including a buncher cavity for REGAE, a normal conducting cavity for arrival time stabilization at FLASH and ultra-fast guns for the AXSIS project is presented in this thesis. Using RF cavities caused a revolution in accelerators and made it possible to generate high energy particle beams. In advanced accelerators, cavities are not only used to increase the particle energy but they are also widely used to improve the beam quality and additionally for beam diagnostic purposes. In the present dissertation, such applications are discussed. First, design of a buncher cavity which compresses the bunch at the REGAE facility is presented. The design pursues improving the mode separation of the cavity. The simulation result illustrates that the difference between the operating mode and its adjacent mode has been increased from 2 MHz for the existing cavity to 9.5 MHz for the new design. In the second part, a normal conducting cavity is discussed, which will be used to regulate the arrival time ofthe bunches at FLASH and at the European XFEL. The designed cavity is able to correct the arrival time jitter of ± 150 fs in order to provide femtosecond precision synchronization between the electron beam and the external laser pulses. Thermal, wakefield and multipacting simulations have also been performed for the designed cavity in order to evaluate its operation efficiency. In advanced accelerators however RF cavities should be replaced by novel structures to accelerate the particles in shorter distances using higher operating frequency. To this end, ultra-fast guns are designed which will be discussed in the last part of this work. The designed guns accelerate the electrons from their rest mass up to 2 MeV using a single cycle THz signal with a total energy of 2 mJ.

  15. Progress on the Design of a Perpendicularly Biased 2nd Harmonic Cavity for the Fermilab Booster

    Madrak, R. L. [Fermilab; Dey, J. E. [Fermilab; Duel, K. L. [Fermilab; Kuharik, J. C. [Fermilab; Pellico, W. A. [Fermilab; Reid, J. S. [Fermilab; Romanov, G. [Fermilab; Slabough, M. [Fermilab; Sun, D. [Fermilab; Tan, C. Y. [Fermilab; Terechkine, I. [Fermilab

    2016-10-01

    perpendicularly biased 2nd harmonic cavity is being designed and built for the Fermilab Booster. Its purpose is to flatten the bucket at injection and thus change the longitudinal beam distribution to decrease space charge effects. It can also help at extraction. The cavity frequency range is 76 – 106 MHz. The power amplifier will be built using the Y567B tetrode, which is also used for the fundamental mode cavities in the Fermilab Booster. We discuss recent progress on the cavity, the biasing solenoid design and plans for testing the tuner's garnet material

  16. Design of a high-power Nd:YAG Q-switched laser cavity

    Singh, Ikbal; Kumar, Avinash; Nijhawan, O. P.

    1995-06-01

    An electro-optically Q-switched Nd:YAG laser resonator that uses two end prisms placed orthogonally perpendicular to each other has been designed. This configuration improves the stability of the resonator and does not alter the characteristics of the electro-optical Q switch. The outcoupling ratio of the cavity is optimized by a change in the azimuthal angle of a phase-matched Porro prism placed at one end of the cavity. The prism placed at the other end of the cavity is designed so that it introduces a phase change of Pi , regardless of its orientation and index of refraction, resulting in a more efficient and stable cavity.

  17. Challenges in resonant cavity biosensor design: collection efficiency and specificity

    Armani, Andrea M.; Mehrabani, Simin; Sun, Victoria; McBirney, Samantha; Hawk, Rasheeda M.; Gungor, Eda; Lee, Michele

    2014-03-01

    Optical cavities have successfully demonstrated the ability to detect a wide range of analytes with exquisite sensitivity. However, optimizing other parameters of the system, such as collection efficiency and specificity, have remained elusive. This presentation will discuss some of the recent work in this area, including 3D COMSOL Multiphysics models including mass transfer and binding kinetics of different cavity geometries and covalent attachment methods for a wide range of biological and synthetic moieties. A few representative experimental demonstrations will also be presented.

  18. PAL-XFEL cavity beam position monitor pick-up design and beam test

    Lee, Sojeong, E-mail: sojung8681@postech.ac.kr; Park, Young Jung; Kim, Changbum; Kim, Seung Hwan; Shin, Dong Cheol; Han, Jang-Hui; Ko, In Soo

    2016-08-11

    As an X-ray Free Electron Laser, PAL-XFEL is about to start beam commissioning. X-band cavity beam position monitor (BPM) is used in the PAL-XFEL undulator beam line. Prototypes of cavity BPM pick-up were designed and fabricated to test the RF characteristics. Also, the beam test of a cavity BPM pick-up was done in the Injector Test Facility (ITF). In the beam test, the raw signal properties of the cavity BPM pick-up were measured at a 200 pC bunch charge. According to the RF test and beam test results, the prototype cavity BPM pick-up design was confirmed to meet the requirements of the PAL-XFEL cavity BPM system.

  19. A high conversion-gain Q-band InP DHBT subharmonic mixer using LO frequency doubler

    Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor

    2008-01-01

    The paper presents analysis and design of a Q-band subharmonic mixer (SHM) with high conversion gain. The SHM consists of a local oscillator (LO) frequency doubler, RF pre-amplifier, and single-ended mixer. The SHM has been fabricated in a high-speed InP double heterojunction bipolar transistor (...

  20. Electromagnetic design issues in elliptic superconducting radio frequency cavity for H- LINAC

    Kumar, V.; Jana, A.R.; Gaur, R.

    2013-01-01

    Multi-cell elliptic superconducting radiofrequency (SCRF) cavities are used for efficient acceleration of a high power charged particle beam for a wide range of velocities, typically corresponding to β = 0.5 to ∼ 1, where β is the particle speed in unit of speed of light. Electromagnetic design of such cavities involves careful optimization of the cavity geometry with several design constraints. In this paper, we discuss a generalized approach to optimize the design to achieve maximum acceleration gradient and field flatness, while ensuring that the effect due to higher order modes supported by the cavity are within acceptable limits. Study of detuning in the cavity resonance frequency due to mechanical pressure associated with electromagnetic field inside the cavity, known as Lorentz Force Detuning (LFD), plays an important role in optimizing the scheme for stiffening of the cavity. Electromagnetic design calculations performed for SCRF cavities of medium energy section of 1 GeV H - injector linac for the proposed Indian Spallation Neutron Source (ISNS) at Raja Ramanna Centre for Advanced Technology are presented in the paper highlighting all these important design issues. (author)

  1. Mechanical design and fabrication processes for the ALS third-harmonic cavities

    Franks, M.; Henderson, T.; Hernandez, K.; Otting, D.; Plate, D.; Rimmer, R.

    1999-01-01

    It is planned to install five third-harmonic (1.5 GHz) RF Cavities in May/June 1999 as an upgrade to the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL). This paper presents mechanical design features, their experiences in using electronic design models to expedite the manufacturing process, and the fabrication processes employed to produce these cavities for the ALS. They discuss some of the lessons learned from the PEP-II RF Cavity design and fabrication, and outline the improvements incorporated in the new design. They also report observations from the current effort

  2. Creating geometrically robust designs for highly sensitive problems using topology optimization: Acoustic cavity design

    Christiansen, Rasmus E.; Lazarov, Boyan S.; Jensen, Jakob S.

    2015-01-01

    Resonance and wave-propagation problems are known to be highly sensitive towards parameter variations. This paper discusses topology optimization formulations for creating designs that perform robustly under spatial variations for acoustic cavity problems. For several structural problems, robust...... and limitations are discussed. In addition, a known explicit penalization approach is considered for comparison. For near-uniform spatial variations it is shown that highly robust designs can be obtained using the double filter approach. It is finally demonstrated that taking non-uniform variations into account...... further improves the robustness of the designs....

  3. High beta lasing in micropillar cavities with adiabatic layer design

    Lermer, M.; Gregersen, Niels; Lorke, M.

    2013-01-01

    We report on lasing in optically pumped adiabatic micropillar cavities, based on the AlAs/GaAs material system. A detailed study of the threshold pump power and the spontaneous emission β factor in the lasing regime for different diameters dc is presented. We demonstrate a reduction of the thresh...... of the threshold pump power by over 2 orders of magnitude from dc = 2.25 μm down to 0.95 μm. Lasing with β factors exceeding 0.5 shows that adiabatic micropillars are operating deeply in the cavity quantum electrodynamics regime....

  4. Subharmonic excitation in an HTGR core

    Bezler, P.; Curreri, J.R.

    1977-01-01

    The occurrence of subharmonic resonance in a series of blocks with clearance between blocks and with springs on the outer most ends is the subject of this paper. This represents an HTGR core response to an earthquake input. An analytical model of the cross section of this type of core is a series of blocks arranged horizontally between outer walls. Each block represents many graphite hexagonal core elements acting in unison as a single mass. The blocks are of unequal size to model the true mass distribution through the core. Core element elasticity and damping characteristics are modeled with linear spring and viscous damping units affixed to each block. The walls and base represent the core barell or core element containment structure. For forced response calculations, these boundaries are given prescribed motions. The clearance between each block could be the same or different with the total clearance duplicating that of the entire core. Spring packs installed between the first and last block and the boundaries model the boundary elasticity. The system non-linearity is due to the severe discontinuity in the interblock elastic forces when adjacent blocks collide. A computer program using a numerical integration scheme was developed to solve for the response of the system to arbitrary inputs

  5. Steam exit flow design for aft cavities of an airfoil

    Storey, James Michael; Tesh, Stephen William

    2002-01-01

    Turbine stator vane segments have inner and outer walls with vanes extending therebetween. The inner and outer walls have impingement plates. Steam flowing into the outer wall passes through the impingement plate for impingement cooling of the outer wall surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. A skirt or flange structure is provided for shielding the steam cooling impingement holes adjacent the inner wall aerofoil fillet region of the nozzle from the steam flow exiting the aft nozzle cavities. Moreover, the gap between the flash rib boss and the cavity insert is controlled to minimize the flow of post impingement cooling media therebetween. This substantially confines outflow to that exiting via the return channels, thus furthermore minimizing flow in the vicinity of the aerofoil fillet region that may adversely affect impingement cooling thereof.

  6. Design of a high-power test model of the PEP-II rf cavity

    Schwarz, H.D.; Bell, R.A.; Hodgson, J.A.

    1993-05-01

    The design of a normal-conducting high-power test cavity (HPTC) for PEP-II is described. The cavity includes HOM loading waveguides and provisions for testing two alternate input coupling schemes. 3-D electromagnetic field simulations provided input information for the surface power deposition. Finite element codes were utilized for thermal and stress analyses of the cavity to arrive at a suitable mechanical design capable of handling the high power dissipation. The mechanical design approach with emphasis on the cooling channel layout and mechanical stress reduction is described

  7. Design, prototyping, and testing of a compact superconducting double quarter wave crab cavity

    Xiao, Binping; Alberty, Luis; Belomestnykh, Sergey; Ben-Zvi, Ilan; Calaga, Rama; Cullen, Chris; Capatina, Ofelia; Hammons, Lee; Li, Zenghai; Marques, Carlos; Skaritka, John; Verdu-Andres, Silvia; Wu, Qiong

    2015-04-01

    We proposed a novel design for a compact superconducting crab cavity with a double quarter wave (DQWCC) shape. After fabrication and surface treatments, this niobium proof-of-principle cavity was tested cryogenically in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service in the Large Hadron Collider luminosity upgrade. The cavity's electromagnetic properties are well suited for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the required 3.34 MV for a crab cavity in the future High Luminosity LHC. In this paper, we present the design, prototyping, and results from testing the DQWCC.

  8. Electromagnetic design of a β=0.9, 650 MHz elliptic superconducting radio frequency cavity

    Jana, Arup Ratan; Kumar, V.

    2011-01-01

    We have recently performed two-dimensional (2D) electromagnetic design studies of a β=0.9, 650 MHz, elliptic superconducting radio frequency (SCRF) cavity using electromagnetic field solver code SUPERFISH. We have evolved the design starting from the design parameters of β=1, 1300 MHz, TESLA design SCRF cavity and then scaled it for the β=0.9 and 650 MHz case. The design has been optimized for minimizing the SCRF cavity power loss. One of the important parameters in the design of such elliptic SCRF cavities is the wall angle, which is defined as the vertical angle made by the common tangent to the iris and equator ellipses. Generally, there is a constraint on the minimum value of the wall angle, which is decided by the mechanical considerations, ease of chemical cleaning etc. In our optimization studies, we have first explored the case when there is no such constraint on wall angle. We find that from the point of view of low cavity power dissipation, the optimized design has a re-entrant geometry, where the wall angle is negative. We then perform design optimization, keeping the constraint that the wall angle should be greater than 5 degree. Keeping this constraint, we find that our optimized design parameters for the single cell match closely with the design parameters reported for Project-X. We discuss the results of 2D electromagnetic field calculations for this design using SUPERFISH. In the next, we have performed the design studies of the multi-cell β=0.9, 650 MHz, elliptic SCRF cavity. The design parameters of end-cells are optimized such that the frequency of the end-cell is matched to that of mid-cells. We have studied all the normal modes for the multi-cell cavity. The frequency of different normal modes is also calculated using a finite element code ANSYS and results are compared with those obtained using SUPERFISH. The field flatness, which is an important design criterion, is also studied. For multi-cell cavity, another important aspect is the cell

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

    Wang, Haipeng; Cheng, Guangfeng; Ciovati, Gianluigi; Henry, James; Kneisel, Peter; Rimmer, Robert; Slack, Gary; Turlington, Larry; waldschmidt, Geoff; Nassiri, Alireza

    2010-01-01

    A squashed, elliptical supercondconducting (SC) cavity with waveguide dampers on the beam pipes has currently been chosen as the baseline design 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.

  10. Designing the Four Rod Crab Cavity for the High-Luminosity LHC upgrade.

    Hall, Ben

    2014-01-01

    This thesis presents the design for a novel compact crab cavity for the HL-LHC upgrade at CERN, Geneva. The LHC requires 400MHz RF cavities that can provide up to 10MV transverse gradient across two to three cavities with suit- ably low surface fields for continual operation. As a result, a cavity design was required that would be optimised to these new parameters. From initial design studies based on Jefferson Laboratory’s CEBAF deflector, extensive optimiza- tion was carried out to design a superconducting crab cavity, dubbed the Four Rod Crab Cavity (4RCC). The design underwent several iterations throughout the course of the project due to changing requirements from CERN, particularly space requirements inside the LHC. In addition, it was decided that a focus on field flatness was required. An aluminium prototype was then constructed from the finalised and computer-simulated design to confirm the designed field flat- ness. Additional computer simulation studies using CST were performed to en-...

  11. A 2 MW, 170 GHz coaxial cavity gyrotron - experimental verification of the design of main components

    Piosczyk, B [Forschungszentrum Karlsruhe, Association EURATOM-FZK, Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM), Postfach 3640, D-76021 Karlsruhe (Germany); Dammertz, G [Forschungszentrum Karlsruhe, Association EURATOM-FZK, Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM), Postfach 3640, D-76021 Karlsruhe (Germany); Dumbrajs, O [Department of Engineering Physics and Mathematics, Helsinki University of Technology, Association EURATOM-TEKES, FIN-02150 Espoo (Finland)] (and others)

    2005-01-01

    A 2 MW, CW, 170 GHz coaxial cavity gyrotron is under development in cooperation between European Research Institutions (FZK Karlsruhe, CRPP Lausanne, HUT Helsinki) and the European tube industry (TED, Velizy, France). The design of critical components has recently been examined experimentally at FZK Karlsruhe with a short pulse ({approx} few ms) coaxial cavity gyrotron. This gyrotron uses the same cavity and the same quasioptical (q.o.) RF-output system as designed for the industrial prototype and a very similar electron gun.

  12. The design of a five-cell high-current superconducting cavity

    Li Yongming; Zhu Feng; Quan Shengwen; Liu Kexin; Nassiri, Ali

    2012-01-01

    Energy recovery linacs are promising for achieving high average current with superior beam quality. The key component for accelerating such high-current beams is the superconducting radio-frequency cavity. The design of a 1.3 GHz five-cell high-current superconducting cavity has been carried out under cooperation between Peking University and the Argonne National Laboratory. The radio-frequency properties, damping of the higher order modes, multipacting and mechanical features of this cavity have been discussed and the final design is presented. (authors)

  13. Electromagnetic and mechanical design of gridded radio-frequency cavity windows

    Alsharo' a, Mohammad M. [Illinois Inst. of Technology, Chicago, IL (United States)

    2004-12-01

    Electromagnetic, thermal and structural analyses of radio-frequency (RF) cavities were performed as part of a developmental RF cavity program for muon cooling. RF cavities are necessary to provide longitudinal focusing of the muons and to compensate for their energy loss. Closing the cavity ends by electrically conducting windows reduces the power requirement and increases the on-axis electric field for a given maximum surface electric field. Many factors must be considered in the design of RF cavity windows. RF heating can cause the windows to deform in the axial direction of the cavity. The resulting thermal stresses in the window must be maintained below the yield stress of the window material. The out-of-plane deflection must be small enough so that the consequent frequency shift is tolerable. For example, for an 805 MHz cavity, the out-of-plane deflection must be kept below 25 microns to prevent the frequency of the cavity from shifting more than 10 kHz. In addition, the window design should yield smooth electric and magnetic fields, terminate field leakage beyond the window, and minimize beam scattering. In the present thesis, gridded-tube window designs were considered because of their high structural integrity. As a starting point in the analysis, a cylindrical pillbox cavity was considered as a benchmark problem. Analytical and finite element solutions were obtained for the electric and magnetic fields, power loss density, and temperature profile. Excellent agreement was obtained between the analytical and finite element results. The finite element method was then used to study a variety of gridded-tube windows. It was found that cooling of the gridded-tube windows by passing helium gas inside the tubes significantly reduces the out-of-plane deflection and the thermal stresses. Certain tube geometries and grid patterns were found to satisfy all of the design requirements.

  14. Design of inductively detuned RF extraction cavities for the Relativistic Klystron Two Beam Accelerator

    Henestroza, E.; Yu, S.S.; Li, H.

    1995-04-01

    An inductively detuned traveling wave cavity for the Relativistic Klystron Two Beam Accelerator expected to extract high RF power at 11. 424 GHz for the 1 TeV Center of Mass Next Linear Collider has been designed. Longitudinal beam dynamics studies led to the following requirements on cavity design: (a) Extraction of 360 MW of RF power with RF component of the current being 1.15 kAmps at 11.424 GHz, (b) Inductively detuned traveling wave cavity with wave phase velocity equal to 4/3 the speed of light, (c) Output cavity with appropriate Q ext and eigenfrequency for proper matching. Furthermore, transverse beam dynamics require low shunt impedances to avoid the beam break-up instability. We describe the design effort to meet these criteria based on frequency-domain and time-domain computations using 2D- and 3D- electromagnetic codes

  15. Design of a multi beam klystron cavity from its single beam parameters

    Kant, Deepender, E-mail: dkc@ceeri.ernet.in; Joshi, L. M. [CSIR-Central Electronics Engineering Research Institute, Pilani (India); Janyani, Vijay [Department of ECE, MNIT, Jaipur (India)

    2016-03-09

    The klystron is a well-known microwave amplifier which uses kinetic energy of an electron beam for amplification of the RF signal. There are some limitations of conventional single beam klystron such as high operating voltage, low efficiency and bulky size at higher power levels, which are very effectively handled in Multi Beam Klystron (MBK) that uses multiple low purveyance electron beams for RF interaction. Each beam propagates along its individual transit path through a resonant cavity structure. Multi-Beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3D code only. The present paper shall discuss the design of multi beam RF cavities for klystrons operating at 2856 MHz (S-band) and 5 GHz (C-band) respectively. The design approach uses some scaling laws for finding the electron beam parameters of the multi beam device from their single beam counter parts. The scaled beam parameters are then used for finding the design parameters of the multi beam cavities. Design of the desired multi beam cavity can be optimized through iterative simulations in CST Microwave Studio.

  16. Design of a multi beam klystron cavity from its single beam parameters

    Kant, Deepender; Joshi, L. M.; Janyani, Vijay

    2016-01-01

    The klystron is a well-known microwave amplifier which uses kinetic energy of an electron beam for amplification of the RF signal. There are some limitations of conventional single beam klystron such as high operating voltage, low efficiency and bulky size at higher power levels, which are very effectively handled in Multi Beam Klystron (MBK) that uses multiple low purveyance electron beams for RF interaction. Each beam propagates along its individual transit path through a resonant cavity structure. Multi-Beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3D code only. The present paper shall discuss the design of multi beam RF cavities for klystrons operating at 2856 MHz (S-band) and 5 GHz (C-band) respectively. The design approach uses some scaling laws for finding the electron beam parameters of the multi beam device from their single beam counter parts. The scaled beam parameters are then used for finding the design parameters of the multi beam cavities. Design of the desired multi beam cavity can be optimized through iterative simulations in CST Microwave Studio.

  17. Design and analysis of magnetic shield for 650 MHz SCRF cavity

    Thakur, Vanshree; Jain, Vikas; Das, S.; Shinde, R.S.; Joshi, S.C.

    2015-01-01

    Five-cell, 650 MHz Superconducting RF (SCRF) cavity is being developed at RRCAT for the Injector Linac of proposed ISNS project. The SCRF cavity needs to be shielded effectively from earth magnetic field. The external magnetic field can cause magnetic field trapping that limits the performance of SCRF cavity. The allowable limit of earth magnetic field in the cavity surface is < 10 mG. The magnetic shielding analysis carried out for 650 MHz dressed SCRF cavity is presented in this paper. For axial magnetic field shielding analysis, 2-D code PANDIRA has been used. A 2-D axisymmetric geometry (cylinder of Cryoperm10 sheet with 460 mm diameter of various thickness and 1100 mm length) has been modelled and analyzed in the presence of 240 mG external axial magnetic field. The influence of partial opening of 120 mm diameter at both ends of the cylinder on magnetic field pattern inside the shielded region has been evaluated. The transverse magnetic shielding analysis in the presence of 500 mG transverse external field has been carried out using OPERA 3D code. The flux leakage through the major openings for cavity supports, ports on the shield is investigated and accordingly the openings are designed to minimize the leakage. Inference of material thickness on the magnetic shielding for reducing magnetic field below specified limit has been investigated. Details of design and analysis of magnetic shield for SCRF cavity will be discussed in this paper. (author)

  18. Design, fabrication and comparison of two power combiners: cylindrical and coaxial cavities

    A M Poursaleh

    2017-08-01

    Full Text Available Resonant structure is one of the proposed methods in combining power in RF systems of  RF accelerators. In this structure, fabrication of RF power divider or combiner using coaxial and cylindrical cavity is important. In this study, two combiners, in the same frequency band, are designed and fabricated; and their results are compared. The experimental results confirmed the simulation results and showed that compared with cyclical cavity, the power combiner with coaxial cavity is smaller, more easily adjustable, and is more suitable for use in RF systems of RF accelerators

  19. Conceptual design of the RF accelerating cavities for a superconducting cyclotron

    Maggiore, M.; Calabretta, L.; Di Giacomo, M.; Rifuggiato, D.; Battaglia, D.; Piazza, L.

    2006-01-01

    A superconducting cyclotron accelerating ions up to 250 A MeV, for medical applications and radioactive ions production is being studied at Laboratori Nazionali del Sud in Catania. The radio frequency (RF) system, working in the fourth harmonic, is based on four normal conducting radio frequency cavities operating at 93 MHz. This paper describes an unusual multi-stem cavity design, performed with 3D electromagnetic codes. Our aim is to obtain a cavity, completely housed inside the cyclotron, with a voltage distribution ranging from 65 kV in the injection region to a peak value of 120 kV in the extraction region, and having a low power consumption

  20. Design and construction of planar mm-wave accelerating cavity structures

    Kang, Y.W.; Kustom, R.L.; Nassiri, A.; Song, J.J.; Feineman, A.D.; Illinois Univ., Chicago, IL

    1995-01-01

    Feasibility studies on the planar millimeter-wave cavity structures have been made. The structures could be used for linear accelerators, free electron lasers, mm-wave amplifiers, or mm-wave undulators. The cavity structures are intended to be manufactured by using DXL (deep x-ray lithography) microfabrication technology. The frequency of operation can be about 30GHz to 300GHz. For most applications, a complete structure consists of two identical planar half structures put together face-to-face. Construction and properties of constant gradient structures that have been investigated so far will be discussed. These cavity structures have been designed for 120GHz 2π/3-mode operation

  1. Design, prototyping, and testing of a compact superconducting double quarter wave crab cavity

    Binping Xiao

    2015-04-01

    Full Text Available We proposed a novel design for a compact superconducting crab cavity with a double quarter wave (DQWCC shape. After fabrication and surface treatments, this niobium proof-of-principle cavity was tested cryogenically in a vertical cryostat. The cavity is extremely compact yet has a low frequency of 400 MHz, an essential property for service in the Large Hadron Collider luminosity upgrade. The cavity’s electromagnetic properties are well suited for this demanding task. The demonstrated deflecting voltage of 4.6 MV is well above the required 3.34 MV for a crab cavity in the future High Luminosity LHC. In this paper, we present the design, prototyping, and results from testing the DQWCC.

  2. Design features of a seven-cell high-gradient superconducting cavity

    Liska, D.J.; Ledford, J.; Black, S.; Spalek, G.; DiMarco, J.N.

    1992-01-01

    A cavity development program is in place at Los Alamos National Laboratory to evaluate structures that could be used to accelerate pions. The work is being guided by the conceptual design of PILAC, a high-gradient superconducting linac for raising the energy of rapidly decaying intense pion beams generated by Los Alamos Meson Physics Facility (LAMPF) to 1 GeV. The specification requires a cavity gradient of 12.5 MV/m at 805 MHz. The design of a seven-cell prototype cavity to achieve these high gradients has been completed by the Accelerator Technology division. The cavity is presently under procurement for high power testing a 2.0 K in 1993

  3. Principles for designing proteins with cavities formed by curved β sheets

    Marcos, Enrique; Basanta, Benjamin; Chidyausiku, Tamuka M.; Tang, Yuefeng; Oberdorfer, Gustav; Liu, Gaohua; Swapna, G. V. T.; Guan, Rongjin; Silva, Daniel-Adriano; Dou, Jiayi; Pereira, Jose Henrique; Xiao, Rong; Sankaran, Banumathi; Zwart, Peter H.; Montelione, Gaetano T.; Baker, David

    2017-01-12

    Active sites and ligand-binding cavities in native proteins are often formed by curved β sheets, and the ability to control β-sheet curvature would allow design of binding proteins with cavities customized to specific ligands. Toward this end, we investigated the mechanisms controlling β-sheet curvature by studying the geometry of β sheets in naturally occurring protein structures and folding simulations. The principles emerging from this analysis were used to design, de novo, a series of proteins with curved β sheets topped with α helices. Nuclear magnetic resonance and crystal structures of the designs closely match the computational models, showing that β-sheet curvature can be controlled with atomic-level accuracy. Our approach enables the design of proteins with cavities and provides a route to custom design ligand-binding and catalytic sites.

  4. Representation of subharmonic functions in a half-plane

    Malyutin, K G; Sadik, N

    2007-01-01

    The theory of subharmonic functions of finite order is based to a considerable extent on integral formulae. In the present paper representations are obtained for subharmonic functions in the upper half-plane with more general growth γ(r) than finite order. The main result can be stated as follows. Let γ(r) be a growth function such that either lnγ(r) is a convex function of ln r or the lower order of γ(r) is infinite. Then for each proper subharmonic function v of growth γ(r) there exist an unbounded set R of positive numbers and a family (u R :R element of R) of proper subharmonic functions in the upper half-plane C + such that 1) the full measures of the u R in the discs |z|≤R are equal to the full measure of the function v-u R →0 uniformly on compact subsets of C + as R→∞, R element of R; 3) the function family {u R :R element of R} satisfies the growth constraints uniformly in R, that is, T(r,u R )≤Aγ(Br)/r, where A and B are constants and T(r, · ) is the growth characteristic. Bibliography: 16 titles.

  5. Discussion of mechanical design for pressured cavity-air-receiver in solar power tower system

    Fan, Zhilin; Zhang, Yaoming; Liu, Deyou; Wang, Jun; Liu, Wei [Hohai Univ., Nanjing (China). New Materials and Energy Sources Research and Exploitation Inst.

    2008-07-01

    In 2005, Hohai university and Nanjing Chunhui science and technology Ltd. of China, cooperating with Weizmann Institute of Science and EDIG Ltd. of Israel, built up a 70kWe solar power tower test plant in Nanjing, Jiangsu province, China, which was regarded as the first demonstration project to demonstrate the feasibility of solar power tower system in China. The system consists of heliostats field providing concentrated sunlight, a solar tower with a height of 33 meter, a pressured cavity-air-receiver transforming solar energy to thermal energy, a modified gas turbine adapting to solar power system, natural gas subsystem for solar-hybrid generation, cooling water subsystem for receiver and CPC, controlling subsystem for whole plant, et al. In this system, air acts as actuating medium and the system works in Brayton cycle. Testing results show that solar power tower system is feasible in China. To promote the development of solar powered gas turbine system and the pressured cavity-air-receiver technology in China, it is necessary to study the mechanical design for pressured Cavity-air-receiver. Mechanical design of pressured cavity-air-receiver is underway and some tentative principles for pressured cavity-air-receiver design, involving in power matching, thermal efficiency, material choosing, and equipment security and machining ability, are presented. At the same time, simplified method and process adapted to engineering application for the mechanical design of pressured cavity-air-receiver are discussed too. Furthermore, some design parameters and appearance of a test sample of pressured cavity-air-receiver designed in this way is shown. It is appealed that, in China, the research in this field should be intensified and independent knowledge patents for pivotal technological equipments such as receiver in solar power tower system should be formed. (orig.)

  6. A split-cavity design for the incorporation of a DC bias in a 3D microwave cavity

    Cohen, M.A.; Yuan, M.; de Jong, B.W.A.; Beukers, Ewout; Bosman, S.J.; Steele, G.A.

    2017-01-01

    We report on a technique for applying a DC bias in a 3D microwave cavity. We achieve this by isolating the two halves of the cavity with a dielectric and directly using them as DC electrodes. As a proof of concept, we embed a variable capacitance diode in the cavity and tune the resonant

  7. A novel, highly efficient cavity backshort design for far-infrared TES detectors

    Bracken, C.; de Lange, G.; Audley, M. D.; Trappe, N.; Murphy, J. A.; Gradziel, M.; Vreeling, W.-J.; Watson, D.

    2018-03-01

    In this paper we present a new cavity backshort design for TES (transition edge sensor) detectors which will provide increased coupling of the incoming astronomical signal to the detectors. The increased coupling results from the improved geometry of the cavities, where the geometry is a consequence of the proposed chemical etching manufacturing technique. Using a number of modelling techniques, predicted results of the performance of the cavities for frequencies of 4.3-10 THz are presented and compared to more standard cavity designs. Excellent optical efficiency is demonstrated, with improved response flatness across the band. In order to verify the simulated results, a scaled model cavity was built for testing at the lower W-band frequencies (75-100 GHz) with a VNA system. Further testing of the scale model at THz frequencies was carried out using a globar and bolometer via an FTS measurement set-up. The experimental results are presented, and compared to the simulations. Although there is relatively poor comparison between simulation and measurement at some frequencies, the discrepancies are explained by means of higher-mode excitation in the measured cavity which are not accounted for in the single-mode simulations. To verify this assumption, a better behaved cylindrical cavity is simulated and measured, where excellent agreement is demonstrated in those results. It can be concluded that both the simulations and the supporting measurements give confidence that this novel cavity design will indeed provide much-improved optical coupling for TES detectors in the far-infrared/THz band.

  8. Designs of two and three cavity gyroklystron amplifiers operating at fundamental, second, and fourth harmonics

    Saraph, G.P.; Lawson, W.; Latham, P.E.; Cheng, J.; Castle, M.

    1995-01-01

    Two and three cavity, co-axial, relativistic gyroklystron amplifiers are investigated for driving future linear colliders. Detailed designs of gyroklystrons operating at fundamental (8.568 GHz), second (17.136 GHz), and fourth harmonic (34.272 GHz) frequencies are presented. Numerical simulations predict over 40% efficiency, 45-50 dB gain, and 100-160 MW power level for the fundamental and second harmonic designs. It is shown that introducing a penultimate (buncher) cavity significantly improves efficiency and gain of the second harmonic amplifier. The fourth harmonic design has a modest efficiency of 10-15%

  9. Analytic evaluation of LAMPF II Booster Cavity design

    Friedrichs, C.C.

    1985-01-01

    Through the past few decades, a great deal of sophistication has evolved in the numeric codes used to evaluate electromagnetically resonant structures. The numeric methods are extremely precise, even for complicated geometries, whereas analytic methods require a simple uniform geometry and a simple, known mode configuration if the same precision is to be obtained. The code SUPERFISH, which is near the present state-of-the-art of numeric methods, does have the following limitations: No circumferential geometry variations are permissible; there are no provisions for magnetic or dielectric losses; and finally, it is impractical (because of the complexity of the code) to modify it to extract particular bits of data one might want that are not provided by the code as written. This paper describes how SUPERFISH was used as an aid in derivating an analytic model of the LAMPF II Booster Cavity. Once a satisfactory model was derived, simple FORTRAN codes were generated to provide whatever data was required. The analytic model is made up of TEM- and radial-mode transmission-line sections, as well as lumped elements where appropriate. Radial transmission-line equations, which include losses, were not found in any literature, and the extension of the lossless equations to include magnetic and dielectric losses are included in this paper

  10. Mechanical design of 56 MHz superconducting RF cavity for RHIC collider

    Pai, C.; Ben-Zvi, I.; Burrill, A.; Chang, X.; McIntyre, G.; Than, Y.; Tuozzolo, J.; Wu, Q.

    2011-03-28

    A 56 MHz Superconducting RF Cavity operating at 4.4K is being constructed for the RHIC collider. This cavity is a quarter wave resonator with beam transmission along the centerline. This cavity will increase collision luminosity by providing a large longitudinal bucket for stored bunches of RHIC ion beam. The major components of this assembly are the niobium cavity with the mechanical tuner, its titanium helium vessel and vacuum cryostat, the support system, and the ports for HOM and fundamental dampers. The cavity and its helium vessel must meet equivalent safety with the ASME pressure vessel code and it must not be sensitive to frequency shift due to pressure fluctuations from the helium supply system. Frequency tuning achieved by a two stage mechanical tuner is required to meet performance parameters. This tuner mechanism pushes and pulls the tuning plate in the gap of niobium cavity. The tuner mechanism has two separate drive systems to provide both coarse and fine tuning capabilities. This paper discusses the design detail and how the design requirements are met.

  11. Status of the mechanical design of the 650 MHz cavities for Project X

    Barbanotti, S.; Grimm, C.; Champion, M.; Foley, M.; Ginsburg, C.M.; Gonin, I.; Peterson, T.; Ristori, L.; Yakovlev, V.; /Fermilab

    2011-03-01

    In the high-energy section of the Project X Linac, acceleration of H{sup -} ions takes place in superconducting cavities operating at 650 MHz. Two families of five-cell elliptical cavities are planned: beta = 0.61 and beta = 0.9. A specific feature of the Project X Linac is low beam loading, and thus, low bandwidth and higher sensitivity to microphonics. Efforts to optimize the mechanical design of the cavities to improve their mechanical stability in response to the helium bath pressure fluctuations will be presented. These efforts take into account constraints such as cost and ease of fabrication. Also discussed will be the overall design status of the cavities and their helium jackets. The proposed design of the 3 GeV Project X superconducting (SC) Linac employs 650 MHz five-cell elliptical cavities to accelerate 1.0 mA of average H-beam current in the 160-3000 MeV energy range. The 650 MHz region of the Linac is divided into two sections with two different geometric phase velocity factors: beta = 0.61 to cover the 160-520 MeV range and beta = 0.9 to cover the 520-3000 MeV range. Approximately 40 beta = 0.61 and 150 beta = 0.9 cavities are currently planned for the project. An R&D program is in progress at FNAL, in collaboration with TJNAF and India, to develop the 650 MHz cavities for the proposed Linac design. This R&D program includes the design and fabrication of several beta = 0.61 and beta = 0.9 single-cell prototypes for evaluation prior to production of the five-cell cavities. FNAL has contracted AES to fabricate the beta = 0.9 prototypes, while TJNAF is building beta = 0.61 prototypes of their own design. In the remainder of this paper we will restrict our discussion to the five-cell beta = 0.9 cavities.

  12. Design, fabrication and low power RF testing of a prototype beta=1, 1050 MHz cavity developed for electron linac

    Sarkar, S.; Mondal, J.; Mittal, K.C.

    2013-01-01

    A single cell 1050 MHz β = 1 elliptical cavity has been designed for possible use in High energy electron accelerator. A prototype Aluminium cavity has been fabricated by die punch method and low power testing of the cavity has been carried out by using VNA. The fundamental mode frequency of the prototype cavity is found out to be 1051.38 MHz and Q (loaded) and Q0 values corresponding to 2 modes are 8439 and 10013 respectively. Cell to cell coupling coefficient is 1.82 % from measurement which matches with the designed value (1.84%). The higher order mode frequencies are also measured and electric field of the cavity is confirmed by bead pull method. Low power RF measurements on the prototype cavity indicate that the critical RF parameters (Qo, f, Kc etc) for the cavity are consistent with the designed value. (author)

  13. Design and performance of a new induction furnace for heat treatment of superconducting radiofrequency niobium cavities.

    Dhakal, Pashupati; Ciovati, Gianluigi; Rigby, Wayne; Wallace, John; Myneni, Ganapati Rao

    2012-06-01

    Superconducting radio frequency (SRF) cavities made of high purity niobium (Nb) are the building blocks of many modern particle accelerators. The fabrication process includes several cycles of chemical and heat treatment at low (∼120 °C) and high (∼800 °C) temperatures. In this contribution, we describe the design and performance of an ultra-high-vacuum furnace which uses an induction heating system to heat treat SRF cavities. Cavities are heated by radiation from the Nb susceptor. By using an all-niobium hot zone, contamination of the Nb cavity by foreign elements during heat treatment is minimized and allows avoiding subsequent chemical etching. The furnace was operated up to 1400 °C with a maximum pressure of ∼1 × 10(-5) Torr and the maximum achievable temperature is estimated to be higher than 2000 °C. Initial results on the performance of a single cell 1.5 GHz cavity made of ingot Nb heat treated at 1200 °C using this new induction furnace and without subsequent chemical etching showed a reduction of the RF losses by a factor of ∼2 compared to cavities made of fine-grain Nb which underwent standard chemical and heat treatments.

  14. Design of a spin-flip cavity for the measurement of the antihydrogen hyperfine structure

    Kroyer, T

    2008-01-01

    In the framework of the ASACUSA collaboration at the CERN Antiproton Decelerator an experiment for precisely testing the CPT invariance of the hydrogen hyperfine structure is currently being designed. An integral part of the set-up is the 1.42 GHz spin-flipping cavity, which should have a good field homogeneity over the large aperture of the antihydrogen beam. After the evaluation of various approaches a structure based on a resonant stripline is proposed as a concrete cavity design. For this structure the field homogeneity, undesired modes, coupling and power issues are discussed in detail.

  15. Development of 400- to 450-MHz RFQ resonator-cavity mechanical designs

    Hansborough, L.D.

    1982-01-01

    In the development of the radio-frequency quadrupole (RFQ) linac, the resonator cavity's mechanical design may be a challenge similar in magnitude to that of the development of the accelerator structure itself. Experience with the all-copper 425-MHz RFQ proof-of-principle linac has demonstrated that the resonator cavity must be structurally stiff and easily tunable. This experience has led to development of copper-plated steel structures having vanes that may be moved within a cylinder for tuning. Design of a flexible vane-to-cylinder radio-frequency (rf) joint, the vane, and the cylinder has many constraints dictated by the small-diameter cavities in the 400-MHz-frequency region. Two types of flexible, mechanical vane-to-cylinder rf joints are being developed at Los Alamos: the C-seal and the rf clamp-joint

  16. Methodology for the structural design of single spoke accelerating cavities at Fermilab

    Passarelli, Donato; Merio, Margherita; Ristori, Leonardo

    2016-01-01

    Fermilab is planning to upgrade its accelerator complex to deliver a more powerful and intense proton-beam for neutrino experiments. In the framework of the so-called Proton Improvement Plan-II (PIP-II), we are designing and developing a cryomodule containing superconducting accelerating cavities, the Single Spoke Resonators of type 1 (SSR1). In this paper, we present the sequence of analysis and calculations performed for the structural de- sign of these cavities, using the rules of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC). The lack of an accepted procedure for addressing the design, fabrication, and inspection of such unique pressure vessels makes the task demanding and challenging every time. Several factors such as exotic materials, unqualified brazing procedures, limited nondestructive examination, and the general R&D nature of these early generations of cavity design, conspire to make it impractical to obtain full compliance with all ASME BPVC requirements. However, the presented approach allowed us to validate the design of these new generation of single spoke cavities with values of maximum allowable working pressure that exceed the safety requirements. This set of rules could be used as a starting point for the structural design and development of similar objects.

  17. Optimum thermal design of microchannel heat sink with triangular reentrant cavities

    Xia Guodong; Chai Lei; Wang Haiyan; Zhou Mingzheng; Cui Zhenzhen

    2011-01-01

    The effect of geometric parameters on water flow and heat transfer characteristics in microchannel heat sink with triangular reentrant cavities is numerically investigated. A three-dimensional laminar flow model, consisting of Navier-Stokes equations and energy conservation equation, with the conjugate heat transfer between the silicon base and water taken into consideration is solved numerically. In order to find the optimum geometric parameters, four variables, representing the distance and geometry of the triangular reentrant cavity, are designed. It is found that the vortices in the triangular reentrant cavities lead to chaotic advection and can greatly enhance the convective fluid mixing. The thermal and hydraulic boundary layers are interrupted and the repeated developing flow enhances heat transfer in the constant cross-section segment. Furthermore, the effects of the four design variables on heat transfer augmentation and pressure drop penalty are investigated depending on different Reynolds numbers by using the simulated annealing method. Based on the thermal enhancement factor performance maps, the optimal geometric parameters are obtained in principle. - Research highlights: → The microchannels with different triangular reentrant cavities are numerically investigated. → The heat transfer enhancement attributes to fluid mixing and redeveloped thermal boundary layers. → The optimal distance and geometry of the triangular reentrant cavity are obtained in principle.

  18. Design of an L-band normally conducting RF gun cavity for high peak and average RF power

    Paramonov, V., E-mail: paramono@inr.ru [Institute for Nuclear Research of Russian Academy of Sciences, 60-th October Anniversary prospect 7a, 117312 Moscow (Russian Federation); Philipp, S. [Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Rybakov, I.; Skassyrskaya, A. [Institute for Nuclear Research of Russian Academy of Sciences, 60-th October Anniversary prospect 7a, 117312 Moscow (Russian Federation); Stephan, F. [Deutsches Elektronen-Synchrotron DESY, Platanenallee 6, D-15738 Zeuthen (Germany)

    2017-05-11

    To provide high quality electron bunches for linear accelerators used in free electron lasers and particle colliders, RF gun cavities operate with extreme electric fields, resulting in a high pulsed RF power. The main L-band superconducting linacs of such facilities also require a long RF pulse length, resulting in a high average dissipated RF power in the gun cavity. The newly developed cavity based on the proven advantages of the existing DESY RF gun cavities, underwent significant changes. The shape of the cells is optimized to reduce the maximal surface electric field and RF loss power. Furthermore, the cavity is equipped with an RF probe to measure the field amplitude and phase. The elaborated cooling circuit design results in a lower temperature rise on the cavity RF surface and permits higher dissipated RF power. The paper presents the main solutions and results of the cavity design.

  19. Subharmonic edge waves on a large, shallow island

    Foda, Mostafa A.

    1988-08-01

    Subharmonic resonance of edge waves by incident and reflected waves has been studied thus far for the case of a plane infinite beach. The analysis will be extended here to the case of a curved coastline, with a large radius of curvature and slowly varying beach slope in the longshore direction. It will be shown that the effects of such slow beach slope changes on a propagating edge wave are similar to the familiar shoaling effects on incident waves. The case of subharmonic edge wave generation on large shallow islands will be discussed in detail. The nonlinear analysis will show that within a certain range of island sizes, the generation mechanism can produce a stable standing edge wave around the island. For larger islands the solution disintegrates into two out-of-phase envelopes of opposite-going edge waves. For still larger islands, the generated progressive edge waves become unstable to sideband modulations.

  20. Computer-aided design of the RF-cavity for a high-power S-band klystron

    Kant, D.; Bandyopadhyay, A. K.; Pal, D.; Meena, R.; Nangru, S. C.; Joshi, L. M.

    2012-08-01

    This article describes the computer-aided design of the RF-cavity for a S-band klystron operating at 2856 MHz. State-of-the-art electromagnetic simulation tools SUPERFISH, CST Microwave studio, HFSS and MAGIC have been used for cavity design. After finalising the geometrical details of the cavity through simulation, it has been fabricated and characterised through cold testing. Detailed results of the computer-aided simulation and cold measurements are presented in this article.

  1. Subharmonic structure of Shapiro steps in frustrated superconducting arrays

    Kim, S.; Kim, B.J.; Choi, M.Y.

    1995-01-01

    Two-dimensional superconducting arrays with combined direct and alternating applied currents are studied both analytically and numerically. In particular, we investigate in detail current-voltage characteristics of a square array with 1/2 flux quantum per plaquette and triangular arrays with 1/2 and 1/4 flux quantum per plaquette. At zero temperature reduced equations of motion are obtained through the use of the translational symmetry present in the systems. The reduced equations lead to a series of subharmonic steps in addition to the standard integer and fractional giant Shapiro steps, producing devil's staircase structure. This devil's staircase structure reflects the existence of dynamically generated states in addition to the states originating from degenerate ground states in equilibrium. Widths of the subharmonic steps as functions of the amplitudes of alternating currents display Bessel-function-type behavior. We also present results of extensive numerical simulations, which indeed reveal the subharmonic steps together with their stability against small thermal fluctuations. Implications for topological invariance are also discussed

  2. Surface wave resonance and chirality in a tubular cavity with metasurface design

    Qin, Yuzhou; Fang, Yangfu; Wang, Lu; Tang, Shiwei; Sun, Shulin; Liu, Zhaowei; Mei, Yongfeng

    2018-06-01

    Optical microcavities with whispering-gallery modes (WGMs) have been indispensable in both photonic researches and applications. Besides, metasurfaces, have attracted much attention recently due to their strong abilities to manipulate electromagnetic waves. Here, combining these two optical elements together, we show a tubular cavity can convert input propagating cylindrical waves into directed localized surface waves (SWs), enabling the circulating like WGMs along the wall surface of the designed tubular cavity. Finite element method (FEM) simulations demonstrate that such near-field WGM shows both large chirality and high local field. This work may stimulate interesting potential applications in e.g. directional emission, sensing, and lasing.

  3. Use of Active Learning to Design Wind Tunnel Runs for Unsteady Cavity Pressure Measurements

    Ankur Srivastava

    2014-01-01

    Full Text Available Wind tunnel tests to measure unsteady cavity flow pressure measurements can be expensive, lengthy, and tedious. In this work, the feasibility of an active machine learning technique to design wind tunnel runs using proxy data is tested. The proposed active learning scheme used scattered data approximation in conjunction with uncertainty sampling (US. We applied the proposed intelligent sampling strategy in characterizing cavity flow classes at subsonic and transonic speeds and demonstrated that the scheme has better classification accuracies, using fewer training points, than a passive Latin Hypercube Sampling (LHS strategy.

  4. Design and Testing of the MIT-Bates Stern-Gerlach Polarimeter Cavity

    Cameron, P; Luccio, A U; MacKay, W W

    2005-01-01

    Historically, beam polarization measurement has been accomplished by scattering experiments, with the attendant complexity of target and detector installation and operation, and smallness and uncertainty of analyzing powers. The purpose of the present effort is to accomplish fast and accurate polarization measurement not as a scattering experiment, but rather as conventional beam instrumentation, with a resonant cavity pickup. This requires that the coupling of the beam magnetic moment to the pickup be enhanced to bring the signal above the noise floor, and that coupling of the beam charge to the pickup be diminished to reduce the dynamic range problem. We discuss details of cavity design that have been implemented to accomplish these ends. Presently, it is planned to install the cavity in the Bates Ring in early May of this year. Beyond polarimetry, successful polarization measurement will verify the underlying principles, and by pickup/kicker reciprocity will open the serious consideration of the possibilit...

  5. Design of horizontal test cryostat for testing two 650 MHz cavities: cryogenic considerations

    Khare, P.; Gilankar, S.; Kush, P. K.; Lakshminarayanan, A.; Choubey, R.; Ghosh, R.; Jain, A.; Patel, H.; Gupta, P. D.; Hocker, A.; Ozelis, J. P.; Geynisman, M.; Reid, C.; Poloubotko, V.; Mitchell, D.; Peterson, T. J.; Nicol, T. H.

    2017-02-01

    Horizontal Test Cryostat has been designed for testing two 650 MHz "dressed" Superconducting Radio Frequency (SCRF) cavities in a single testing cycle at Raja Ramanna Centre for Advanced Technology, India (RRCAT) in collaboration with Fermi National Accelerator Laboratory, USA (FNAL). This cryostat will facilitate testing of two 5-cell 650 MHz SCRF cavities, in CW or pulsed regime, for upcoming High Intensity Superconducting Proton Accelerator projects at both countries. Two such HTS facilities are planned, one at RRCAT for Indian Spallation Neutron Source project (ISNS), which is on the horizon, and the other at FNAL, USA. A test cryostat, a part of horizontal test stand-2 (HTS-2) will be set up at RRCAT for Indian project. In order to maximize the utility of this facility, it can also be used to test two dressed 9-cell 1.3 GHz cavities and other similarly-sized devices. The facility assumes, as an input, the availability of liquid nitrogen at 80 K and liquid helium at 4.5 K and 2 K, with a refrigeration capacity of approximately 50 W at 2 K. Design work of cryostat has been completed and now procurement process is in progress. This paper discusses salient features of the cryostat. It also describes different design calculations and ANSYS analysis for cool down of few subsystems like cavity support system and liquid nitrogen cooled thermal radiation shield of horizontal test cryostat..

  6. A New RF System for the CEBAF Normal Conducting Cavities

    Curt Hovater; Hai Dong; Alicia Hofler; George Lahti; John Musson; Tomasz Plawski

    2004-01-01

    The CEBAF Accelerator at Jefferson Lab is a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. CEBAF also has numerous normal conducting cavities for beam conditioning in the injector and for RF extraction to the experimental halls. The RF systems that presently control these cavities are becoming expensive to maintain, therefore a replacement RF control system is now being developed. For the new RF system, cavity field control is maintained digitally using an FPGA which contains the feedback algorithm. The system incorporates digital down conversion, using quadrature under-sampling at an IF frequency of 70 MHz. The VXI bus-crate was chosen as the operating platform because of its excellent RFI/EMI properties and its compatibility with the EPICS control system. The normal conducting cavities operate at both the 1497 MHz accelerating frequency and the sub-harmonic frequency of 499 MHz. To accommodate this, the ne w design will use different receiver-transmitter daughter cards for each frequency. This paper discusses the development of the new RF system and reports on initial results

  7. Conceptual design of a high real-estate gradient cavity for a SRF ERL

    Xu, Chen; Stony Brook University, NY; Ben-Zvi, Ilan; Stony Brook University, NY; Hao, Yue

    2017-01-01

    The term “real-estate gradient” is used to describe the energy gain provided by an accelerating structure per actual length it takes in the accelerator. given that the length of the tunnel available for the accelerator is constrained, the real-estate gradient is an important measure of the efficiency of a given accelerator structure. When designing an accelerating cavity to be efficient in this sense, the unwanted Higher Order Mode (HOM) fields should be reduced by suitable HOM dampers. This is a particularly important consideration for high current operation. The additional RF components might take longitude space and reduce the total accelerating efficiency. We describe a new high efficiency 5-cell cavity with the dampers included. The total length of the cavity is reduced by 13% as compared to a more conventional design without compromising the cavity fundamental-mode performance. In addition, the HOM impedance is reduced for a higher Beam-Break-Up (BBU) threshold of operating current. In this article, we consider an example, a possible application at the eRHIC Energy Recovery Linac (ERL).

  8. Conceptual design of a high real-estate gradient cavity for a SRF ERL

    Xu, Chen; Ben-Zvi, Ilan; Hao, Yue; Xin, Tianmu; Wang, Haipeng

    2017-10-01

    The term "real-estate gradient" is used to describe the energy gain provided by an accelerating structure per actual length it takes in the accelerator. given that the length of the tunnel available for the accelerator is constrained, the real-estate gradient is an important measure of the efficiency of a given accelerator structure. When designing an accelerating cavity to be efficient in this sense, the unwanted Higher Order Mode (HOM) fields should be reduced by suitable HOM dampers. This is a particularly important consideration for high current operation. The additional RF components might take longitude space and reduce the total accelerating efficiency. We describe a new high efficiency 5-cell cavity with the dampers included. The total length of the cavity is reduced by 13% as compared to a more conventional design without compromising the cavity fundamental-mode performance. In addition, the HOM impedance is reduced for a higher Beam-Break-Up (BBU) threshold of operating current. In this paper, we consider an example, a possible application at the eRHIC Energy Recovery Linac (ERL).

  9. Fractal apertures in waveguides, conducting screens and cavities analysis and design

    Ghosh, Basudeb; Kartikeyan, M V

    2014-01-01

    This book deals with the design and analysis of fractal apertures in waveguides, conducting screens and cavities using numerical electromagnetics and field-solvers. The aim is to obtain design solutions with improved accuracy for a wide range of applications. To achieve this goal, a few diverse problems are considered. The book is organized with adequate space dedicated for the design and analysis of fractal apertures in waveguides, conducting screens, and cavities, microwave/millimeter wave applications followed by detailed case-study problems to infuse better insight and understanding of the subject. Finally, summaries and suggestions are given for future work. Fractal geometries were widely used in electromagnetics, specifically for antennas and frequency selective surfaces (FSS). The self-similarity of fractal geometry gives rise to a multiband response, whereas the  space-filling nature of the fractal geometries makes it an efficient element in antenna and FSS unit cell miniaturization. Until now, no e...

  10. Designing, Probing, and Stabilizing Exotic Fabry-Perot Cavities for Studying Strongly Correlated Light

    Ryou, Albert

    Synthetic materials made of engineered quasiparticles are a powerful platform for studying manybody physics and strongly correlated systems due to their bottom-up approach to Hamiltonian modeling. Photonic quasiparticles called polaritons are particularly appealing since they inherit fast dynamics from light and strong interaction from matter. This thesis describes the experimental demonstration of cavity Rydberg polaritons, which are composite particles arising from the hybridization of an optical cavity with Rydberg EIT, as well as the tools for probing and stabilizing the cavity. We first describe the design, construction, and testing of a four-mirror Fabry-Perot cavity, whose small waist size on the order of 10 microns is comparable to the Rydberg blockade radius. By achieving strong coupling between the cavity photon and an atomic ensemble undergoing electromagnetically induced transparency (EIT), we observe the emergence of the dark-state polariton and characterize its single-body properties as well as the single-quantum nonlinearity. We then describe the implementation of a holographic spatial light modulator for exciting different transverse modes of the cavity, an essential tool for studying polariton-polariton scattering. For compensating optical aberrations, we employ a digital micromirror device (DMD), combining beam shaping with adaptive optics to produce diffraction-limited light. We quantitatively measure the purity of the DMD-produced Hermite-Gauss modes and confirm up to 99.2% efficiency. One application of the technique is to create Laguerre-Gauss modes, which have been used to probe synthetic Landau levels for photons in a twisted, nonplanar cavity. Finally, we describe the implementation of an FPGA-based FIR filter for stabilizing the cavity. We digitally cancel the acoustical resonances of the feedback-controlled mechanical system, thereby demonstrating an order-of-magnitude enhancement in the feedback bandwidth from 200 Hz to more than 2 k

  11. New design concepts for ferrite-tuned low-energy-booster cavities

    Schaffer, G.

    1991-05-01

    The design concepts for ferrite-tuned accelerating cavities discussed in this paper differ from conventional solutions using thick ferrite toroids for frequency tuning. Instead, tuners consisting of an array of ferrite-loaded striplines are investigated. These promise more efficient cooling and higher operational reliability. Layout examples for the SSC-LEB rf system are presented (tuning range 47.5 to 59.8 MHz, repetition frequency 10 Hz). 15 refs., 4 figs., 1 tab

  12. Conceptual design of elliptical cavities for intensity and position sensitive beam measurements in storage rings

    Sanjari, M S; Chen, X; Hülsmann, P; Litvinov, Yu A; Nolden, F; Piotrowski, J; Steck, M; Stöhlker, Th

    2015-01-01

    Position sensitive beam monitors are indispensable for the beam diagnostics in storage rings. Apart from their applications in the measurements of beam parameters, they can be used in non-destructive in-ring decay studies of radioactive ion beams as well as enhancing precision in the isochronous mass measurement technique. In this work, we introduce a novel approach based on cavities with elliptical cross-section, in order to compensate the limitations of known designs for the application in ion storage rings. The design is aimed primarily for future heavy ion storage rings of the FAIR project. The conceptual design is discussed together with simulation results. (paper)

  13. Subharmonic energy-gap structure in superconducting weak links

    Flensberg, K.; Hansen, Jørn Bindslev; Octavio, M.

    1988-01-01

    We present corrected calculations of the subharmonic energy-gap structure using the model of Octavio, Tinkham, Blonder, and Klapwijk, which includes the effect of normal scattering in the weak link. We show that while the overall predictions of this model do not change qualitatively, the details...... of the predicted curves are different and in better agreement with experiment. We also present calculation of the current-voltage characteristics and of the excess currents for T=0, as the normal scattering parameter Z is varied. We also show how the calculation can be shortened using symmetry arguments...

  14. Algorithm improvement for phase control of subharmonic buncher

    Zhang Junqiang; Yu Luyang; Yin Chongxian; Zhao Minghua; Zhong Shaopeng

    2011-01-01

    To realize digital phase control of subharmonic buncher,a low level radio frequency control system using down converter, IQ modulator and demodulator techniques, and commercial PXI system, was developed on the platform of LabVIEW. A single-neuron adaptive PID (proportional-integral-derivative) control algorithm with ability of self learning was adopted, satisfying the requirements of phase stability. By comparison with the traditional PID algorithm in field testing, the new algorithm has good stability, fast response and strong anti-interference ability. (authors)

  15. Second-generation PVCC design with a dielectric light injector and polyhedron interior cavity

    Ortabasi, Ugur; Winston, Roland; Ellis, Scott

    2006-08-01

    The Photovoltaic Cavity Converter (PVCC) under development is a novel approach to convert highly concentrated solar radiation into electricity via a photon entrapment process and subsequent spectral stripping. Equipped with a multi-bandgap, single junction cell system PVCC circumvents most of the present limitations of the four (or more)-junction cell systems with vertical architecture. Our previous studies have shown that the PVCC concept has the potential to reach a collective conversion efficiency of 50% in the near term. Based on our past experiences regarding the cavity geometry and the light injection method we have developed a second generation design for the PVCC that overcomes the limitations of the first generation prototype.

  16. Subharmonic beam-loading in electron linear accelerators

    Gallagher, W.J.

    1983-01-01

    The intention of operating an electron linear accelerator subharmonically beam loaded for free electron laser application requires justification of the beam-loaded energy gain equation. The mode of operation typically planned is 5 to 10 nanocoulombs single RF cycle pulses at 25 to 50 nanosecond intervals. This inquiry investigates the details of this sort of beam loading and discusses the performance achievable. Several other investigations of single bunch beam loading have been undertaken, notably at SLAC, where it has been found experimentally that the beam-loading varies directly as the bunch charge and independently of its energy; that investigation also included radiation effects of the wake field and losses owing to parasitic effects of higher order modes. In the case of beam loading where there are multiple pulses transiting at the same time, and spaced far enough apart that significant RF power is introduced between pulses, the energy gain may be calculated by dividing the waveguide into a number of segments, each equal in length to the integral of the interpulse time and the local group velocity. Equations which reveal that the net energy gain in the steady state is the sum of the energy gains in these segments, which compute the initial field intensity, and which calculate the energy gain in the subharmonic case on the basis of the equivalent beam current are presented

  17. Design, Fabrication and Testing of Medium-Beta 650 MHz SRF Cavity Prototypes for Project-X

    Marhauser, F.; Clemens, W.A.; Henry, J.; Kneisel, P.; Martin, R.; Rimmer, R.A.; Slack, G.; Turlington, L.; Williams, R.S.

    2011-01-01

    A new type of superconducting radio frequency (SRF) cavity shape with a shallow equator dome to reduce electron impact energies for suppressing multipacting barriers has been proposed. The shape is in consideration for the first time in the framework of Project-X to design a potential multi-cell cavity candidate for the medium-beta section of the SRF proton CW linac operating at 650 MHz. Rationales covering the design of the multi-cell cavity, the manufacture, post-processing and high power testing of two single-cell prototypes are presented.

  18. Thermal design studies in superconducting rf cavities: Phonon peak and Kapitza conductance

    A. Aizaz

    2010-09-01

    Full Text Available Thermal design studies of superconducting radio frequency (SRF cavities involve two thermal parameters, namely the temperature dependent thermal conductivity of Nb at low temperatures and the heat transfer coefficient at the Nb-He II interface, commonly known as the Kapitza conductance. During the fabrication process of the SRF cavities, Nb sheet is plastically deformed through a deep drawing process to obtain the desired shape. The effect of plastic deformation on low temperature thermal conductivity as well as Kapitza conductance has been studied experimentally. Strain induced during the plastic deformation process reduces the thermal conductivity in its phonon transmission regime (disappearance of phonon peak by 80%, which may explain the performance limitations of the defect-free SRF cavities during their high field operations. Low temperature annealing of the deformed Nb sample could not recover the phonon peak. However, moderate temperature annealing during the titanification process recovered the phonon peak in the thermal conductivity curve. Kapitza conductance measurements for the Nb-He II interface for various surface topologies have also been carried out before and after the annealing. These measurements reveal consistently increased Kapitza conductance after the annealing process was carried out in the two temperature regimes.

  19. Design and development progress of a LLRF control system for a 500 MHz superconducting cavity

    Lee, Y. S.; Kim, H. W.; Song, H. S.; Lee, J. H.; Park, K. H.; Yu, I. H.; Chai, J. S.

    2012-07-01

    The LLRF (low-level radio-frequency) control system which regulates the amplitude and the phase of the accelerating voltage inside a RF cavity is essential to ensure the stable operation of charged particle accelerators. Recent advances in digital signal processors and data acquisition systems have allowed the LLRF control system to be implemented in digitally and have made it possible to meet the higher demands associated with the performance of LLRF control systems, such as stability, accuracy, etc. For this reason, many accelerator laboratories have completed or are completing the developments of digital LLRF control systems. The digital LLRF control system has advantages related with flexibility and fast reconfiguration. This paper describes the design of the FPGA (field programmable gate array) based LLRF control system and the status of development for this system. The proposed LLRF control system includes an analog front-end, a digital board (ADC (analog to digital converter), DAC (digital to analog converter), FPGA, etc.) and a RF & clock generation system. The control algorithms will be implemented by using the VHDL (VHSIC (very high speed integrated circuits) hardware description language), and the EPICS (experiment physics and industrial control system) will be ported to the host computer for the communication. In addition, the purpose of this system is to control a 500 MHz RF cavity, so the system will be applied to the superconducting cavity to be installed in the PLS storage ring, and its performance will be tested.

  20. Design of a compact high-speed optical modulator based on a hybrid plasmonic nanobeam cavity

    Javid, Mohammad Reza; Miri, Mehdi; Zarifkar, Abbas

    2018-03-01

    A hybrid plasmonic electro-optic modulator based on a polymer-filled one dimensional photonic crystal nanobeam (1D PhCNB) cavity is proposed here. In the proposed structure the optical intensity modulation is realized by shifting the resonant wavelength of the cavity through electrically tuning the refractive index of the electro-optic polymer in the hybrid plasmonic waveguide. As a result of the subwavelength light confinement in the hybrid plasmonic waveguide and the compact footprint of the 1D PhCNB cavity, the designed modulator has the small overall footprint of 3 . 6 μm2 and the required wavelength shift can be achieved by applying very small actuating power. Three dimensional finite-difference time-domain (3D-FDTD) simulations show that the modulation depth of 10.9 dB, and insertion loss of 1.14 dB, along with very high modulation speed of 224 GHz can be achieved in the proposed modulator with very low modulation energy of 0.75 fJ/bit. A comparison between the performance parameters of the proposed modulator and those of previously reported PhCNB based modulators reveals the superior performance of the proposed structure in terms of modulation speed, energy consumption and overall footprint.

  1. Dependence of the subharmonic signal from contrast agent microbubbles on ambient pressure: A theoretical analysis.

    Jiménez-Fernández, J

    2018-01-01

    This paper investigates the dependence of the subharmonic response in a signal scattered by contrast agent microbubbles on ambient pressure to provide quantitative estimations of local blood pressure. The problem is formulated by assuming a gas bubble encapsulated by a shell of finite thickness with dynamic behavior modeled by a nonlinear viscoelastic constitutive equation. For ambient overpressure compatible with the clinical range, the acoustic pressure intervals where the subharmonic signal may be detected (above the threshold for the onset and below the limit value for the first chaotic transition) are determined. The analysis shows that as the overpressure is increased, all harmonic components are displaced to higher frequencies. This displacement is significant for the subharmonic of order 1/2 and explains the increase or decrease in the subharmonic amplitude with ambient pressure described in previous works. Thus, some questions related to the monotonic dependence of the subharmonic amplitude on ambient pressure are clarified. For different acoustic pressures, quantitative conditions for determining the intervals where the subharmonic amplitude is a monotonic or non-monotonic function of the ambient pressure are provided. Finally, the influence of the ambient pressure on the subharmonic resonance frequency is analyzed.

  2. Design and analysis on fume exhaust system of blackbody cavity sensor for continuously measuring molten steel temperature

    Guohui Mei

    2017-03-01

    Full Text Available Fume exhaust system is the main component of the novel blackbody cavity sensor with a single layer tube, which removes the fume by gas flow along the exhaust pipe to keep the light path clean. However, the gas flow may break the conditions of blackbody cavity and results in the poor measurement accuracy. In this paper, we analyzed the influence of the gas flow on the temperature distribution of the measuring cavity, and then calculated the integrated effective emissivity of the non-isothermal cavity based on Monte-Carlo method, accordingly evaluated the sensor measurement accuracy, finally obtained the maximum allowable flow rate for various length of the exhaust pipe to meet the measurement accuracy. These results will help optimize the novel blackbody cavity sensor design and use it better for measuring the temperature of molten steel.

  3. Dynamic manipulation of the subharmonic scattering of phospholipid-coated microbubbles

    Faez, Telli; Renaud, Guillaume; De Jong, Nico [Biomedical Engineering Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam (Netherlands); Defontaine, Marielle; Calle, Samuel, E-mail: t.faez@erasmusmc.nl [INSERM U930-CNRS ERL3106, Universite Francois Rabelais, UFR Medecine, 10 bd Tonnelle, 37000 Tours (France)

    2011-10-07

    In this paper, the influence of a dynamic variation in the ambient pressure on the subharmonic response of phospholipid-coated microbubbles was investigated. The ambient pressure in water was modulated by a 2.5 kHz acoustic wave with a peak amplitude of 15 kPa. We investigated the fundamental and subharmonic emissions at two driving frequencies: 5 and 10 MHz. The modulation of the bubble radius induced by the dynamic variation in the liquid ambient pressure subsequently causes modulations of the scattered acoustic pressure at the fundamental and subharmonic frequencies (half the fundamental frequency). As a first result, we measured that the variation in the ambient pressure of 15 kPa can modulate the subharmonic amplitude up to 10 dB as compared to the static atmospheric pressure condition. As a second result, we noticed that the relative subharmonic amplitude modulation as a function of the LF acoustic pressure was symmetrical for the 5 MHz driving frequency but asymmetric for 10 MHz. In the latter case, the subharmonic amplitude was more enhanced for an ambient overpressure than reduced for an ambient depression of the same amplitude likely due to the buckling of the lipid shell. However, the fundamental amplitude was symmetrically modulated during bubble compression and expansion. Moreover, subharmonic and fundamental amplitude modulations were found to be either in phase or out of phase with the low-frequency acoustic pressure. Numerical simulations showed that this behavior can be obtained depending on the bubbles' diameter. The highest subharmonic amplitude was measured when microbubbles were insonified at 10 MHz. This fact together with the asymmetry observed in the subharmonic modulation suggests that smaller bubbles with a buckling shell are excited at 10 MHz compared to 5 MHz. These results present new potentials for in vitro characterization of contrast agent microbubbles and possibly a new imaging modality.

  4. A 201 MHz RF cavity design with non-stressed pre-curved Be windows for muon cooling channels

    Li, Derun; Ladran, A.; Staples, J.; Virostek, S.; Zisman, M.; Lau, W.; Yang, S.; Rimmer, R.A.

    2003-01-01

    We present a 201-MHz RF cavity design for muon cooling channels with non-stressed and pre-curved Be foils to terminate the beam apertures. The Be foils are necessary to improve the cavity shunt impedance with large beam apertures needed for accommodating large transverse size muon beams. Be is a low-Z material with good electrical and thermal properties. It presents an almost transparent window to muon beams, but terminates the RF cavity electro-magnetically. Previous designs use pre-stressed flat Be foils in order to keep cavity from detuning resulted from RF heating on the window surface. Be foils are expensive, and it is difficult to make them under desired tension. An alternative design is to use pre-curved and non-stressed Be foils where the buckling direction is known, and frequency shifts can be properly predicted. We will present mechanical simulations on the Be foils in this paper

  5. Design and construction of cavity frequency measurement and tuning systems of traveling wave electron linear accelerator

    S Ahmadiannamin

    2017-08-01

    Full Text Available The main purpose for designing and constructing electroradio frequency linear accelerators is to reach better beam quality with higher power and energy by lower RF power consumption. The main step for this purpose is doing research and development in the area of designing, constructing, measuring and tuning of accelerator RF cavities. Institute for Research in Fundamental Sciences (IPM linear accelerator projecta is the first Iranian project for construction of electrolinear accelerator. In this paper, a brief introduction to construction procedure has been given. Then, the measurement and tuning of a disk-loaded periodic structure before and after tuning was reported. In addition, the detailed design and measurement setup for electric field measurement by perturbation method was investigated  

  6. Design of a 1.42 GHZ spin-flip cavity for antihydrogen atoms

    Caspers, F; Juhasz, B; Mahner, E; Widmann, E

    2010-01-01

    The ground state hyperfine transition frequency of hydrogen is known to a very high precision and therefore the measurement of this transition frequency in antihydrogen is offering one of the most accurate tests of CPT symmetry. The ASACUSA collaboration at CERN will run an experiment designed to produce ground state antihydrogen atoms in a cusp trap. These antihydrogen atoms will pass with a low rate in the order of 1 per second through a spin-flip cavity where they get excited depending on their polarization by a 1.42 GHz magnetic field. Due to the small amount of antihydrogen atoms that will be available the requirement of good field homogeneity is imposed in order to obtain an interaction with as many antihydrogen atoms as possible. This leads to a requirement of an RF field deviation of less than ±10% transverse to the beam direction over a beam aperture with 10 cm diameter. All design aspects of this new spin-flip cavity, including the required field homogeneity and vacuum aspects, are discussed.

  7. RFTech report on cavity design, LLRF & HPRF systems and design integration, & costing

    De Conto, J M; Zimmermann, F

    2013-01-01

    This report highlights results from the EuCARD WP4.3 RFTech network, which was active from April 2009 to July 2013. The objective of RFTech was bringing together RF experts from different laboratories and communities, e.g. proton & electron accelerators, or storage rings & linacs, to exchange ideas and to promote innovation on all aspects of RF technology. RFTech organized 4 primary annual workshops and the organized or co-organized several topical workshops or dedicated sessions in larger conferences, like MIXDES, ICAP 12 etc. The present document highlights the main topics covered during this networking activity. The RFTech activities related to superconducting RF infrastructures are described in the EuCARD report “European Infrastructures for R&D and Test of Superconducting Radio-Frequency Cavities and Cryo-modules” (Wolfgang Weingarten, ISBN 978-83-7207-952-7).

  8. Energy gap subharmonic in characteristics of Y Ba2 Cu3 O7-x microbridges

    Pogrebnyakov, A.V.; Levinsen, M.T.; Sheng, Yu.K.; Frel'toft, T.

    1996-01-01

    The microbridges formed in thin epitaxial Y Ba 2 Cu 3 O 7-x films were investigated. The characteristics of the microbridges exhibited subharmonic gap structures corresponding to large (2Δ = 49 meV) and small (2Δ 2 = 10.3 meV) components of the energy gap at T = 4.2 K. The appearance of the subharmonic gap structures is attributed to the phenomenon of Andreev reflection

  9. Subharmonic gap structure in the characteristics of YBa2Cu3O7-x microbridges

    Pogrebnyakov, A.V.; Levinsen, M.T.; Sheng, Y.Q.; Freltoft, T.

    1996-01-01

    The subharmonic gap structures corresponding to large, 2Δ 1 =48 meV, and small, 2Δ 2 =10.3 meV, components of the energy gap were observed in the first derivatives of the current-voltage characteristics of YBa 2 Cu 3 O 7-x epitaxial thin film microbridges. The appearance of the subharmonic gap structures is attributed to Andreev reflection. (orig.)

  10. Design approach for the development of a cryomodule for compact crab cavities for Hi-Lumi LHC

    Pattalwar, Shrikant; Jones, Thomas; Templeton, Niklas; Goudket, Philippe; McIntosh, Peter; Wheelhouse, Alan; Burt, Graeme; Hall, Ben; Wright, Loren; Peterson, Tom

    2014-01-01

    A prototype Superconducting RF (SRF) cryomodule, comprising multiple compact crab cavities is foreseen to realise a local crab crossing scheme for the "Hi-Lumi LHC", a project launched by CERN to increase the luminosity performance of LHC. A cryomodule with two cavities will be initially installed and tested on the SPS drive accelerator at CERN to evaluate performance with high-intensity proton beams. A series of boundary conditions influence the design of the cryomodule prototype, arising from; the complexity of the cavity design, the requirement for multiple RF couplers, the close proximity to the second LHC beam pipe and the tight space constraints in the SPS and LHC tunnels. As a result, the design of the helium vessel and the cryomodule has become extremely challenging. This paper assesses some of the critical cryogenic and engineering design requirements and describes an optimised cryomodule solution for the evaluation tests on SPS.

  11. Beam dynamics study and superconducting triple spoke cavity design for the EURISOL driver

    Ponton, A.

    2009-07-01

    EURISOL will be the next generation source of intense radioactive ion beams. Its accelerator complex consists of a driver linac, a set of targets and sources and a post-accelerator linac which aims at supplying different experimental areas with the exotic ions. The presented study deals with the driver accelerator: a superconducting RF linac capable of accelerating different ion kinds (D + , 3 He 2+ and H - ) up to a maximal power of 4 MW. First beam dynamics studies pointed out a very good acceleration efficiency when triple spoke cavities working at a frequency of 352 MHz are used in the medium energy part (0.2 < beta < 0.4). Thanks to a novel geometry, the electromagnetic design of the proposed cavity leads to 33 MV/m and 72 mT for the peak electric field and magnetic induction respectively at an ambitious accelerating field of 8 MV/m. The beam transport was then simulated and optimized in the original layout and calculations were also performed considering an alternative, periodic solution, for the low energy part. The 'all-periodic' linac keeps the beam qualities better by strongly reducing the emittance growth and the halo formation. (author)

  12. Investigation on the relationship between overpressure and sub-harmonic response from encapsulated microbubbles

    Wu Jun; Xu Di; Fan Ting-Bo; Zhang Dong

    2014-01-01

    Sub-harmonic component generated from microbubbles is proven to be potentially used in noninvasive blood pressure measurement. Both theoretical and experimental studies are performed in the present work to investigate the dependence of the sub-harmonic generation on the overpressure with different excitation pressure amplitudes and pulse lengths. With 4-MHz ultrasound excitation at an applied acoustic pressure amplitude of 0.24 MPa, the measured sub-harmonic amplitude exhibits a decreasing change as overpressure increases; while non-monotonic change is observed for the applied acoustic pressures of 0.36 MPa and 0.48 MPa, and the peak position in the curve of the sub-harmonic response versus the overpressure shifts toward higher overpressure as the excitation pressure amplitude increases. Furthermore, the exciting pulse with long duration could lead to a better sensitivity of the sub-harmonic response to overpressure. The measured results are explained by the numerical simulations based on the Marmottant model. The numerical simulations qualitatively accord with the measured results. This work might provide a preliminary proof for the optimization of the noninvasive blood pressure measurement through using sub-harmonic generation from microbubbles. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  13. Investigation on the relationship between overpressure and sub-harmonic response from encapsulated microbubbles

    Wu, Jun; Fan, Ting-Bo; Xu, Di; Zhang, Dong

    2014-10-01

    Sub-harmonic component generated from microbubbles is proven to be potentially used in noninvasive blood pressure measurement. Both theoretical and experimental studies are performed in the present work to investigate the dependence of the sub-harmonic generation on the overpressure with different excitation pressure amplitudes and pulse lengths. With 4-MHz ultrasound excitation at an applied acoustic pressure amplitude of 0.24 MPa, the measured sub-harmonic amplitude exhibits a decreasing change as overpressure increases; while non-monotonic change is observed for the applied acoustic pressures of 0.36 MPa and 0.48 MPa, and the peak position in the curve of the sub-harmonic response versus the overpressure shifts toward higher overpressure as the excitation pressure amplitude increases. Furthermore, the exciting pulse with long duration could lead to a better sensitivity of the sub-harmonic response to overpressure. The measured results are explained by the numerical simulations based on the Marmottant model. The numerical simulations qualitatively accord with the measured results. This work might provide a preliminary proof for the optimization of the noninvasive blood pressure measurement through using sub-harmonic generation from microbubbles.

  14. Design and measurement of signal processing system for cavity beam position monitor

    Wang Baopeng; Leng Yongbin; Yu Luyang; Zhou Weimin; Yuan Renxian; Chen Zhichu

    2013-01-01

    In this paper, in order to achieve the output signal processing of cavity beam position monitor (CBPM), we develop a digital intermediate frequency receiver architecture based signal processing system, which consists of radio frequency (RF) front end and high speed data acquisition board. The beam position resolution in the CBPM signal processing system is superior to 1 μm. Two signal processing algorithms, fast Fourier transform (FFT) and digital down converter (DDC), are evaluated offline using MATLAB platform, and both can be used to achieve, the CW input signal, position resolutions of 0.31 μm and 0.10 μm at -16 dBm. The DDC algorithm for its good compatibility is downloaded into the FPGA to realize online measurement, reaching the position resolution of 0.49 μm due to truncation error. The whole system works well and the performance meets design target. (authors)

  15. 670-GHz Schottky Diode-Based Subharmonic Mixer with CPW Circuits and 70-GHz IF

    Chattopadhyay, Goutam; Schlecht, Erich T.; Lee, Choonsup; Lin, Robert H.; Gill, John J.; Mehdi, Imran; Sin, Seth; Deal, William; Loi, Kwok K.; Nam, Peta; hide

    2012-01-01

    GaAs-based, sub-harmonically pumped Schottky diode mixers offer a number of advantages for array implementation in a heterodyne receiver system. Since the radio frequency (RF) and local oscillator (LO) signals are far apart, system design becomes much simpler. A proprietary planar GaAs Schottky diode process was developed that results in very low parasitic anodes that have cutoff frequencies in the tens of terahertz. This technology enables robust implementation of monolithic mixer and frequency multiplier circuits well into the terahertz frequency range. Using optical and e-beam lithography, and conventional epitaxial layer design with innovative usage of GaAs membranes and metal beam leads, high-performance terahertz circuits can be designed with high fidelity. All of these mixers use metal waveguide structures for housing. Metal machined structures for RF and LO coupling hamper these mixers to be integrated in multi-pixel heterodyne array receivers for spectroscopic and imaging applications. Moreover, the recent developments of terahertz transistors on InP substrate provide an opportunity, for the first time, to have integrated amplifiers followed by Schottky diode mixers in a heterodyne receiver at these frequencies. Since the amplifiers are developed on a planar architecture to facilitate multi-pixel array implementation, it is quite important to find alternative architecture to waveguide-based mixers.

  16. Subharmonic Oscillations and Chaos in Dynamic Atomic Force Microscopy

    Cantrell, John H.; Cantrell, Sean A.

    2015-01-01

    The increasing use of dynamic atomic force microscopy (d-AFM) for nanoscale materials characterization calls for a deeper understanding of the cantilever dynamics influencing scan stability, predictability, and image quality. Model development is critical to such understanding. Renormalization of the equations governing d- AFM provides a simple interpretation of cantilever dynamics as a single spring and mass system with frequency dependent cantilever stiffness and damping parameters. The renormalized model is sufficiently robust to predict the experimentally observed splitting of the free-space cantilever resonance into multiple resonances upon cantilever-sample contact. Central to the model is the representation of the cantilever sample interaction force as a polynomial expansion with coefficients F(sub ij) (i,j = 0, 1, 2) that account for the effective interaction stiffness parameter, the cantilever-to-sample energy transfer, and the amplitude of cantilever oscillation. Application of the Melnikov method to the model equation is shown to predict a homoclinic bifurcation of the Smale horseshoe type leading to a cascade of period doublings with increasing drive displacement amplitude culminating in chaos and loss of image quality. The threshold value of the drive displacement amplitude necessary to initiate subharmonic generation depends on the acoustic drive frequency, the effective damping coefficient, and the nonlinearity of the cantilever-sample interaction force. For parameter values leading to displacement amplitudes below threshold for homoclinic bifurcation other bifurcation scenarios can occur, some of which lead to chaos.

  17. Design, fabrication, and optimization of quantum cascade laser cavities and spectroscopy of the intersubband gain

    Dirisu, Afusat Olayinka

    Quantum Cascade (QC) lasers are intersubband light sources operating in the wavelength range of ˜ 3 to 300 mum and are used in applications such as sensing (environmental, biological, and hazardous chemical), infrared countermeasures, and free-space infrared communications. The mid-infrared range (i.e. lambda ˜ 3-30 mum) is of particular importance in sensing because of the strong interaction of laser radiation with various chemical species, while in free space communications the atmospheric windows of 3-5 mum and 8-12 mum are highly desirable for low loss transmission. Some of the requirements of these applications include, (1) high output power for improved sensitivity; (2) high operating temperatures for compact and cost-effective systems; (3) wide tunability; (4) single mode operation for high selectivity. In the past, available mid-infrared sources, such as the lead-salt and solid-state lasers, were bulky, expensive, or emit low output power. In recent years, QC lasers have been explored as cost-effective and compact sources because of their potential to satisfy and exceed all the above requirements. Also, the ultrafast carrier lifetimes of intersubband transitions in QC lasers are promising for high bandwidth free-space infrared communication. This thesis was focused on the improvement of QC lasers through the design and optimization of the laser cavity and characterization of the laser gain medium. The optimization of the laser cavity included, (1) the design and fabrication of high reflection Bragg gratings and subwavelength antireflection gratings, by focused ion beam milling, to achieve tunable, single mode and high power QC lasers, and (2) modeling of slab-coupled optical waveguide QC lasers for high brightness output beams. The characterization of the QC laser gain medium was carried out using the single-pass transmission experiment, a sensitive measurement technique, for probing the intersubband transitions and the electron distribution of QC lasers

  18. RF cavity design exploiting a new derivative-free trust region optimization approach

    Abdel-Karim S.O. Hassan

    2015-11-01

    Full Text Available In this article, a novel derivative-free (DF surrogate-based trust region optimization approach is proposed. In the proposed approach, quadratic surrogate models are constructed and successively updated. The generated surrogate model is then optimized instead of the underlined objective function over trust regions. Truncated conjugate gradients are employed to find the optimal point within each trust region. The approach constructs the initial quadratic surrogate model using few data points of order O(n, where n is the number of design variables. The proposed approach adopts weighted least squares fitting for updating the surrogate model instead of interpolation which is commonly used in DF optimization. This makes the approach more suitable for stochastic optimization and for functions subject to numerical error. The weights are assigned to give more emphasis to points close to the current center point. The accuracy and efficiency of the proposed approach are demonstrated by applying it to a set of classical bench-mark test problems. It is also employed to find the optimal design of RF cavity linear accelerator with a comparison analysis with a recent optimization technique.

  19. Design and Development of an Octopus Thermometric system for the 704 MHZ Single-Cell SPL Cavity at CERN

    Liao, K; Brunner, O; Ciapala, E; Glenat, D; Weingarten, W

    2012-01-01

    The octopus thermometric system is designed for the 704 MHz superconducting proton linac (SPL) cavity to detect hot spots and X-rays caused by normal conducting defects and the impact of emission electrons. This system features an octopus body and tentacle structure for good contact with the cavity and easy assembly, a multiplexing circuit with integrated microprocessor for efficient readout and a high density temperature sensor arrangement in order to complete a high resolution temperature and X-ray map. The first prototype is being manufactured and investigations are undergoing for further development.

  20. Self-demodulation effect on subharmonic response of ultrasound contrast agent

    Daeichin, V.; Faez, T.; Needles, A.; Renaud, G.; Bosch, J. G.; van der Steen, A. F. W.; de Jong, N.

    2012-03-01

    In this work the use of the self-demodulation (S-D) signal as a mean of microbubble excitation at the subharmonic (SH) frequency to enhance the SH emission of ultrasound contrast agent (UCA) is studied. SH emission from the UCA is of interest since it is produced only by the UCA and is free of the artifacts produced in harmonic imaging modes. The S-D wave is a low-frequency signal produced by nonlinear propagation of an ultrasound wave in the medium. Single element transducer experiments and numerical simulations were conducted at 10 MHz to study the effect of the S-D signal on the SH response of the UCA by modifying the envelope of the excitation bursts. For 6 and 20 transmitted cycles, the SH response is increased up to 25 dB and 22 dB because of the S-D stimulation for a burst with a rectangular envelope compared with a Gaussian envelope burst. Such optimized excitations were used in an array-based micro-ultrasound system (Vevo 2100, VisualSonics Inc., Toronto, ON, Canada) at 18 MHz for in vitro validation of SH imaging. This study suggests that a suitable design of the envelope of the transmit excitation to generate a S-D signal at the SH frequency can enhance the SH emission of UCA and real-time SH imaging is feasible with shorter transmit burst (6- cycle) and low acoustic pressure (~150 KPa) at high frequencies (>15 MHz).

  1. Sub-harmonic broadband humps and tip noise in low-speed ring fans.

    Moreau, Stéphane; Sanjose, Marlène

    2016-01-01

    A joint experimental and numerical study has been achieved on a low-speed axial ring fan in clean inflow. Experimental evidence shows large periodic broadband humps at lower frequencies than the blade passing frequencies and harmonics even at design conditions. These sub-harmonic humps are also found to be sensitive to the fan process and consequently to its tip geometry. Softer fans yield more intense humps more shifted to lower frequencies with respect to the fan harmonics. Unsteady turbulent flow simulations of this ring fan mounted on a test plenum have been achieved by four different methods that have been validated by comparing with overall performances and detailed hot-wire velocity measurements in the wake. Noise predictions are either obtained directly or are obtained through Ffowcs Williams and Hawkings' analogy, and compared with narrowband and third-octave power spectra. All unsteady simulations correctly capture the low flow rates, the coherent vortex dynamics in the tip clearance and consequently the noise radiation dominated by the tip noise in the low- to mid-frequency range. Yet, only the scale-adaptive simulation and the lattice Boltzmann method simulations which can describe most of the turbulent structures accurately provide the proper spectral shape and levels, and consequently the overall sound power level.

  2. Experimental observation of acoustic sub-harmonic diffraction by a grating

    Liu, Jingfei, E-mail: benjamin.jf.liu@gatech.edu; Declercq, Nico F., E-mail: declercqdepatin@gatech.edu [Laboratory for Ultrasonic Nondestructive Evaluation “LUNE,” Georgia Tech Lorraine, Georgia Tech-CNRS UMI2958, Georgia Institute of Technology, 2, rue Marconi, Metz 57070 (France)

    2014-06-28

    A diffraction grating is a spatial filter causing sound waves or optical waves to reflect in directions determined by the frequency of the waves and the period of the grating. The classical grating equation is the governing principle that has successfully described the diffraction phenomena caused by gratings. However, in this work, we show experimental observation of the so-called sub-harmonic diffraction in acoustics that cannot be explained by the classical grating equation. Experiments indicate two physical phenomena causing the effect: internal scattering effects within the corrugation causing a phase shift and nonlinear acoustic effects generating new frequencies. This discovery expands our current understanding of the diffraction phenomenon, and it also makes it possible to better design spatial diffraction spectra, such as a rainbow effect in optics with a more complicated color spectrum than a traditional rainbow. The discovery reveals also a possibly new technique to study nonlinear acoustics by exploitation of the natural spatial filtering effect inherent to an acoustic diffraction grating.

  3. Design of rf-cavities in the funnel of accelerators for transmutation technologies

    Krawczyk, F.L.; Bultman, N.K.; Chan, K.D.C.; Martineau, R.L.; Nath, S.; Young, L.M.

    1994-01-01

    Funnels are a key component of accelerator structures proposed for transmutation technologies. In addition to conventional accelerator elements, specialized rf-cavities are needed for these structures. Simulations were done to obtain their electromagnetic field distribution and to minimize the rf-induced heat loads. Using these results a structural and thermal analysis of these cavities was performed to insure their reliability at high average power and to determine their cooling requirements. For one cavity the thermal expansion data in return was used to estimate the thermal detuning

  4. rf power dependence of subharmonic voltage spectra of two-dimensional Josephson-junction arrays

    Hebboul, S.E.; Garland, J.C.

    1993-01-01

    We have measured the rf-bias-current dependence of the ν/2 subharmonic spectral response of planar 300x300 Nb-Au-Nb proximity-coupled Josephson-junction arrays. The ν/2 subharmonic voltage spectrum was examined at two rf-bias frequencies, ν/ν c ∼1.4, 2.0 (ν c ∼120 MHz), and in applied magnetic fields corresponding to f=0,1/2 flux quantum per plaquette. The measurements were compared to analytical predictions for an rf-biased asymmetric superconducting quantum interference device with non-negligble loop inductance and large rf-bias-current amplitudes, based on the resistively shunted Josephson-junction model. Reasonable agreement was found between experiment and theory, suggesting that a possible origin for the observed subharmonic behavior in arrays involves an interplay between array plaquette inductances and junction critical-current variations

  5. Hysteretic Nonlinearity of Sub-harmonic Emission from Ultrasound Contrast Agent Microbubbles

    Qiu Yuan-Yuan; Zhang Dong; Zheng Hai-Rong

    2011-01-01

    Sub-harmonic contrast imaging promises to improve ultrasound imaging quality by taking advantage of increased contrast to tissue signal. The aim of this study is to examine the hysteretic nonlinearity of sub-harmonic component emitted from microbubbles. Two kinds of microbubble solutions, i.e. Sonovue® and a self-developed contrast agent, are utilized in the study. The hysteretic curves for increasing and decreasing acoustic pressure are theoretically predicted by the Marmottant model and confirmed by measurements. The results reveal that for both microbubble solutions, the development of the rising ramp undergoes three stages, i.e. occurrence, growth and saturation; while hysteresis effect appears in the descending ramp. Sonovue® microbubbles exhibit better sub-harmonic performance over the self-developed UCAs microbubbles due to the difference of elastic properties of the shell. (fundamental areas of phenomenology(including applications))

  6. On active disturbance rejection based control design for superconducting RF cavities

    Vincent, John; Morris, Dan; Usher, Nathan [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, East Lansing, MI 48824-1321 (United States); Gao, Zhiqiang, E-mail: z.gao@csuohio.edu [Center for Advanced Control Technologies, Fenn College of Engineering, Cleveland State University, Cleveland, OH 44115-2214 (United States); Zhao Shen; Nicoletti, Achille; Zheng Qinling [Center for Advanced Control Technologies, Fenn College of Engineering, Cleveland State University, Cleveland, OH 44115-2214 (United States)

    2011-07-01

    Superconducting RF (SRF) cavities are key components of modern linear particle accelerators. The National Superconducting Cyclotron Laboratory (NSCL) is building a 3 MeV/u re-accelerator (ReA3) using SRF cavities. Lightly loaded SRF cavities have very small bandwidths (high Q) making them very sensitive to mechanical perturbations whether external or self-induced. Additionally, some cavity types exhibit mechanical responses to perturbations that lead to high-order non-stationary transfer functions resulting in very complex control problems. A control system that can adapt to the changing perturbing conditions and transfer functions of these systems would be ideal. This paper describes the application of a control technique known as 'Active Disturbance Rejection Control' (ARDC) to this problem.

  7. Novel design of electrical sensing interface for prosthetic limbs using optical micro cavities

    Ali, Amir R.; Kamel, Mohamed A.

    2018-04-01

    This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the neural membrane and the prosthetic limb will be actuated accordingly. The element is a WGM dielectric polymeric cavity. WGM based optical cavities can achieve very high values of sensitivity and quality factor; thus, any minute perturbations in the morphology of the cavity can be captured and measured. The action potential signal will produce an applied external electric field on the dielectric cavity causing it to deform due to the electrostriction effect. The resulting deformation will cause WGM shifts in the transmission spectrum of the cavity. Thus, the action potential or the applied electric field can be measured using these shifts. In this paper the action potential signal will be simulated through the use of a function generator and two metal electrodes. The sensing element will be situated between these electrodes to detect the electrical signal passing through. The achieved sensitivity is 27.5 pm/V in measuring the simulated action potential signal; and 0.32 pm/V.m-1 in measuring the applied electric field due to the passage of the simulated signal.

  8. Design of cavities of a standing wave accelerating tube for a 6 MeV electron linear accelerator

    S Zarei

    2017-08-01

    Full Text Available Side-coupled standing wave tubes in  mode are widely used in the low-energy electron linear accelerator, due to high accelerating gradient and low sensitivity to construction tolerances. The use of various simulation software for designing these kinds of tubes is very common nowadays. In this paper, SUPERFISH code and COMSOL are used for designing the accelerating and coupling cavities for a 6 MeV electron linear accelerator. Finite difference method in SUPERFISH code and Finite element method in COMSOL are used to solve the equations. Besides, dimension of accelerating and coupling cavities and also coupling iris dimension are optimized to achieve resonance frequency of 2.9985 MHz and coupling constant of 0.0112. Considering the results of this study and designing of the RF energy injection port subsequently, the construction of 6 MeV electron tube will be provided

  9. Prototype development of radio frequency cavity and quadrupole for ADSS - initial efforts by mechanical design and prototype development section

    Kumar, Manish; Kamble, Sunil; Choughule, L.S.; Kumar, Sunil; Patankar, S.R.; Phalke, V.M.; Dharmik, D.A.; Singh, Tejinder; Ram, Y.; Chaudhari, A.T.; Pathak, Kavindra; Prasad, N.K.; Marathe, V.V.; Matkar, A.W.

    2007-01-01

    Mechanical Design and Prototype Development Section has participated in the efforts for development of RF cavity and Quadrupole for ADSS. Recently prototype Super conducting RF cavity, Radio Frequency Quadrupole (RFQ), Radio Frequency Quadrupole (RFQ) Simulation Chamber and related experimental setups were developed, fabricated and delivered for the characterisation of various relevant parameters. Under the program for development of Super conducting RF Cavity for high-energy section of LINAC of ADS first prototype RF Cavity of ETP copper was developed by machining and brazing process. The prototype cavity having elliptical and circular profile is the heart of this setup. The cavity is made up of two symmetrical cups joined together by welding or brazing. Various methods are being tried out by MD and PDS for the fabrication of cups and joining them together. Manufacturing of cup by machining and joining them by conventional brazing technique to make the cavity was the first step in this direction. Another method of manufacturing and joining viz forming of cup by deep drawing and joining them by EB welding is in progress. RFQ is a versatile and efficient system for accelerating ion beams especially at low energy. It works in quadrupole mode, which is at 350M Hz. RFQ Focuses, Bunches and Accelerates the beam simultaneously. The bunching is done in this RFQ, which results in more than 95% transmission where as in the normal buncher the transmission is less than 40%. The actual RFQ, which is designed for the PURNIMA facility, will be fabricated from OFHC copper that will accelerate a deuteron (D+) ion beam from 50keV to 400keV over its 1.37meter length. For the validation of manufacturing process and characterisation of various parameters at low frequency a 500mm long prototype RFQ in Aluminium with an accuracy of ± 25microns and surface finish of 1.6 micron has been fabricated by MD and PDS. A simplified simulation chamber to facilitate the development of RFQ for

  10. Design and development of RF system for vertical test stand for characterization of superconducting RF cavities

    Mohania, Praveen; Rajput, Vikas; Baxy, Deodatta; Agrawal, Ankur; Mahawar, Ashish; Adarsh, Kunver; Singh, Pratap; Shrivastava, Purushottam

    2011-01-01

    RRCAT is developing a Vertical Test Stand (VTS) to test and qualify 1.3 GHz/650 MHz, SCRF Cavities in collaboration with Fermi National Accelerator Laboratory (FNAL) under Indian Institutions' Fermilab Collaboration. The technical details for VTS is being provided by FNAL, USA. The RF System of VTS needs to provide stable RF power to SCRF cavity with control of amplitude, relative phase and frequency. The incident, reflected, transmitted power and field decay time constant of the cavity are measured to evaluate cavity performance parameters (E, Qo). RF Power is supplied via 500 W Solid State amplifier, 1270-1310 MHz being developed by PHPMS, RRCAT. VTS system is controlled by PXI Platform and National Instruments LabVIEW software. Low Level RF (LLRF) system is used to track the cavity frequency using Phase Locked Loop (PLL). The system is comprised of several integrated functional modules which would be assembled, optimized, and tested separately. Required components and instruments have been identified and procurement for the same is underway. Inhouse development for the Solid State RF amplifier and instrument interfacing is in progress. This paper describes the progress on the development of the RF system for VTS. (author)

  11. Robust Sub-harmonic Mixer at 340 GHz Using Intrinsic Resonances of Hammer-Head Filter and Improved Diode Model

    Wang, Cheng; He, Yue; Lu, Bin; Jiang, Jun; Miao, Li; Deng, Xian-Jin; Xiong, Yong-zhong; Zhang, Jian

    2017-11-01

    This paper presents a sub-harmonic mixer at 340 GHz based on anti-parallel Schottky diodes (SBDs). Intrinsic resonances in low-pass hammer-head filter have been adopted to enhance the isolation for different harmonic components, while greatly minimizing the transmission loss. The application of new DC grounding structure, impedance matching structure, and suspended micro-strip mitigates the negative influences of fabrication errors from metal cavity, quartz substrate, and micro-assembly. An improved lumped element equivalent circuit model of SBDs guarantees the accuracy of simulation, which takes current-voltage (I/V) behavior, capacitance-voltage (C/V) behavior, carrier velocity saturation, DC series resistor, plasma resonance, skin effect, and four kinds of noise generation mechanisms into consideration thoroughly. The measurement indicates that with local oscillating signal of 2 mW, the lowest double sideband conversion loss is 5.5 dB at 339 GHz; the corresponding DSB noise temperature is 757 K. The 3 dB bandwidth of conversion loss is 50 GHz from 317 to 367 GHz.

  12. Cavity design for single-frequency Yb:YAB microchip lasers

    Burns, P.; Dawes, J.M.; Piper, J.A.

    2000-01-01

    Full text: We have proposed a cavity configuration for compact, stable, single-frequency operation in Yb:YAB. Modelling of the cavity output in the infrared and green has shown that sufficient mode discrimination can be achieved within the tuning range of the crystal. Experiments are planned to demonstrate efficient single longitudinal mode infrared operation of the devices that can be extended to include the self-frequency-doubled output. Details of the modelling and preliminary results will be presented at the conference

  13. A Design of Wide Band and Wide Beam Cavity-Backed Slot Antenna Array with Slant Polarization

    Huiying Qi

    2016-01-01

    Full Text Available Design of antenna array under the limitation of restricted size is a challenging problem. Cavity-backed slot antenna is widely used because of its advantages of small size, wide band, and wide beam. In this paper, a design of wide band and wide beam cavity-backed slot antenna array with the slant polarization is proposed. To obtain wide band and wide beam with limited size, the inverted microstrip-fed cavity-backed slot antenna (IMF-CBSA is adopted as the element of 1 × 4 antenna array. The slant polarized antennas and their feeding networks are adopted because of their simple structures. The performance of the proposed antenna array is verified by the simulations and experiments. The measured VSWR < 2 bandwidth is 55% at the center frequency 21.8 GHz, and the gain is larger than 12.2 dB. Experimental results demonstrate that the proposed design achieves wide band and beam with the size of 68 mm × 56 mm × 14.5 mm.

  14. Subharmonic solutions of planar Hamiltonian systems via the Poincaré́-Birkhoff theorem

    Alberto Boscaggin

    2011-06-01

    Full Text Available We revisit some recent results obtained in [1] about the existence of subharmonic solutions for a class of (nonautonomous planar Hamiltonian systems, and we compare them with the existing literature. New applications to undamped second order equations are discussed, as well.

  15. Subharmonic Resonance of Van Der Pol Oscillator with Fractional-Order Derivative

    Yongjun Shen

    2014-01-01

    Full Text Available The subharmonic resonance of van der Pol (VDP oscillator with fractional-order derivative is studied by the averaging method. At first, the first-order approximate solutions are obtained by the averaging method. Then the definitions of equivalent linear damping coefficient (ELDC and equivalent linear stiffness coefficient (ELSC for subharmonic resonance are established, and the effects of the fractional-order parameters on the ELDC, the ELSC, and the dynamical characteristics of system are also analysed. Moreover, the amplitude-frequency equation and phase-frequency equation of steady-state solution for subharmonic resonance are established. The corresponding stability condition is presented based on Lyapunov theory, and the existence condition for subharmonic resonance (ECSR is also obtained. At last, the comparisons of the fractional-order and the traditional integer-order VDP oscillator are fulfilled by the numerical simulation. The effects of the parameters in fractional-order derivative on the steady-state amplitude, the amplitude-frequency curves, and the system stability are also studied.

  16. Subharmonic energy-gap structure and heating effects in superconducting niobium point contacts

    Flensberg, K.; Hansen, Jørn Bindslev

    1989-01-01

    We present experimental data of the temperature-dependent subharmonic energy-gap structure (SGS) in the current-voltage (I-V) curves of superconducting niobium point contacts. The observed SGS is modified by heating effects. We construct a model of the quasiparticle conductance of metallic...

  17. An InP HBT sub-harmonic mixer for E-band wireless communication

    Johansen, Tom Keinicke; Krozer, Viktor

    2010-01-01

    This paper reports on a novel balanced HBT subharmonic mixer (SHM) for E-band wireless communication. An LO spiral type Marchand balun is integrated with the SHM. The SHM has been fabricated in a InP double heterojunction bipolar transistor (DHBT) circuit-oriented technology with fT /fmax = 180GHz...

  18. Design study of an S-band RF cavity of a dual-energy electron LINAC for the CIS

    Lee, Byeong-No; Park, Hyungdal; Song, Ki-baek; Li, Yonggui; Lee, Byung Cheol; Cha, Sung-su; Lee, Jong-Chul; Shin, Seung-Wook; Chai, Jong-seo

    2014-01-01

    The design of a resonance frequency (RF) cavity for the dual-energy S-band electron linear accelerator (LINAC) has been carried out for the cargo inspection system (CIS). This Standing-wave-type RF cavity is operated at a frequency under the 2856-MHz resonance frequency and generates electron beams of 9 MeV (high mode) and 6 MeV (low mode). The electrons are accelerated from the initial energy of the electron gun to the target energy (9 or 6 MeV) inside the RF cavity by using the RF power transmitted from a 5.5-MW-class klystron. Then, electron beams with a 1-kW average power (both high mode and low mode) bombard an X-ray target a 2-mm spot size. The proposed accelerating gradient was 13 MV/m, and the designed Q value was about 7100. On going research on 15-MeV non-destructive inspections for military or other applications is presented.

  19. Impact of polymer film thickness and cavity size on polymer flow during embossing : towards process design rules for nanoimprint lithography.

    Schunk, Peter Randall; King, William P. (Georgia Institute of Technology, Atlanta, GA); Sun, Amy Cha-Tien; Rowland, Harry D. (Georgia Institute of Technology, Atlanta, GA)

    2006-08-01

    This paper presents continuum simulations of polymer flow during nanoimprint lithography (NIL). The simulations capture the underlying physics of polymer flow from the nanometer to millimeter length scale and examine geometry and thermophysical process quantities affecting cavity filling. Variations in embossing tool geometry and polymer film thickness during viscous flow distinguish different flow driving mechanisms. Three parameters can predict polymer deformation mode: cavity width to polymer thickness ratio, polymer supply ratio, and Capillary number. The ratio of cavity width to initial polymer film thickness determines vertically or laterally dominant deformation. The ratio of indenter width to residual film thickness measures polymer supply beneath the indenter which determines Stokes or squeeze flow. The local geometry ratios can predict a fill time based on laminar flow between plates, Stokes flow, or squeeze flow. Characteristic NIL capillary number based on geometry-dependent fill time distinguishes between capillary or viscous driven flows. The three parameters predict filling modes observed in published studies of NIL deformation over nanometer to millimeter length scales. The work seeks to establish process design rules for NIL and to provide tools for the rational design of NIL master templates, resist polymers, and process parameters.

  20. Multiple-bunch-length operating mode design for a storage ring using hybrid low alpha and harmonic cavity method

    Gao, Weiwei, E-mail: gaomqr@mail.ustc.edu.cn [College of Mathematics and Physics, Fujian University of Technology, Fuzhou 350118 (China); Wang, Lin; Li, Heting [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China)

    2017-03-11

    In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.

  1. Thermo mechanical design of normal-conducting deflecting cavities at the Advanced Photon Source for short x-ray pulse generation.

    Brajuskovic, B.; Collins, J.; Den Hartog, P.; Morrison, L.; Waldschmidt, G.

    2008-01-01

    A normal-conducting deflecting cavity is being designed at the Advanced Photon Source (APS) as a part of the short x-ray pulse project intended to provide users with approximately 2 picosecond x-rays. The system will use two pairs of 3-cell cavities in sectors 6ID and 7ID for the generation of the x-ray pulse in the 7ID beamline. The 3-cell cavities are designed to provide the desired beam deflection while absorbing in excess of 4 kW of power from a pulsed rf system and up to 2.6 kW in the damper system of high-order mode (HOM) and low-order mode (LOM) waveguides. Since the cavity frequency is very sensitive to thermal expansion, the cooling water system is designed so that it is able to control cavity temperature to within 0.1 C. This paper describes the optimization of the thermomechanical design of the cavity based on calculation of thermal stresses and displacement caused by the generated heat loads, and presents the design of a cooling water system required for the proper operation of the cavities.

  2. Mechanical design optimization of a single-axis MOEMS accelerometer based on a grating interferometry cavity for ultrahigh sensitivity

    Lu, Qianbo; Bai, Jian; Wang, Kaiwei; Lou, Shuqi; Jiao, Xufen; Han, Dandan; Yang, Guoguang

    2016-08-01

    The ultrahigh static displacement-acceleration sensitivity of a mechanical sensing chip is essential primarily for an ultrasensitive accelerometer. In this paper, an optimal design to implement to a single-axis MOEMS accelerometer consisting of a grating interferometry cavity and a micromachined sensing chip is presented. The micromachined sensing chip is composed of a proof mass along with its mechanical cantilever suspension and substrate. The dimensional parameters of the sensing chip, including the length, width, thickness and position of the cantilevers are evaluated and optimized both analytically and by finite-element-method (FEM) simulation to yield an unprecedented acceleration-displacement sensitivity. Compared with one of the most sensitive single-axis MOEMS accelerometers reported in the literature, the optimal mechanical design can yield a profound sensitivity improvement with an equal footprint area, specifically, 200% improvement in displacement-acceleration sensitivity with moderate resonant frequency and dynamic range. The modified design was microfabricated, packaged with the grating interferometry cavity and tested. The experimental results demonstrate that the MOEMS accelerometer with modified design can achieve the acceleration-displacement sensitivity of about 150μm/g and acceleration sensitivity of greater than 1500V/g, which validates the effectiveness of the optimal design.

  3. A compact 10 kW, 476 MHz solid state radio frequency amplifier for pre-buncher cavity of free electron laser injector linear accelerator

    Mohania, Praveen; Mahawar, Ashish; Shrivastava, Purushottam; Gupta, P. D. [Raja Rammana Centre for Advanced Technology (RRCAT), Indore 452013 (India)

    2013-09-15

    A 10 kW, 476 MHz, 0.1% duty cycle solid state RF amplifier system for driving sub-harmonic, pre-buncher cavity of IR-FEL injector LINAC, has been developed at RRCAT. The 10 kW power is achieved by combining output of eight 1400 W amplifier modules using 8-way planar corporate combiner. The solid state amplifier modules have been developed using 50 V RF LDMOS transistors which although meant for push-pull operation are being used in single ended configuration with matching circuit developed on a thin (25 mils), high dielectric constant (9.7), low loss microwave laminate with an aim to have a compact structure. Ease of fabrication, modularity, small size, and low cost are the important features of this design which could be used as a template for low duty cycle medium to high pulsed power UHF amplifier system.

  4. The Prototype Fundamental Power Coupler For The Spallation Neutron Source Superconducting Cavities: Design And Initial Test Results

    K. M. Wilson; I. E. Campisi; E. F. Daly; G. K. Davis; M. Drury; J. E. Henry; P. Kneisel; G. Myneni; T. Powers; W. J. Schneider; M. Stirbet; Y. Kang; K. Cummings; T. Hardek

    2001-01-01

    Each of the 805 MHz superconducting cavities of the Spallation Neutron Source (SNS) is powered via a coaxial Fundamental Power Coupler (FPC) with a 50 Omega impedance and a warm planar alumina window. The design is derived from the experience of other laboratories; in particular, a number of details are based on the coupler developed for the KEK B-Factory superconducting cavities. However, other design features have been modified to account for the fact that the SNS FPC will transfer a considerably lower average power than the KEK-B coupler. Four prototypes have been manufactured so far, and preliminary tests performed on two of them at Los Alamos National Laboratory (LANL). During these tests, peak powers of over 500 kW were transferred through the couplers in the test stand designed and built for this purpose. This paper gives details of the coupler design and of the results obtained from the RF tests on the test stand during the last few months. A more comprehensive set of tests is planned for the near future

  5. Real-time monitoring of focused ultrasound blood-brain barrier opening via subharmonic acoustic emission detection: implementation of confocal dual-frequency piezoelectric transducers

    Tsai, Chih-Hung; Zhang, Jia-Wei; Liao, Yi-Yi; Liu, Hao-Li

    2016-04-01

    Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contrast-enhanced imaging confirmation after focused ultrasound (FUS) exposure serves as a post-operative indicator of the effectiveness of FUS-BBB opening, however, an indicator that can concurrently report the BBB status and BBB-opening effectiveness is required to provide effective feedback to implement this treatment clinically. In this study, we demonstrate the use of subharmonic acoustic emission detection with implementation on a confocal dual-frequency piezoelectric ceramic structure to perform real-time monitoring of FUS-BBB opening. A confocal dual-frequency (0.55 MHz/1.1 MHz) focused ultrasound transducer was designed. The 1.1 MHz spherically-curved ceramic was employed to deliver FUS exposure to induce BBB-opening, whereas the outer-ring 0.55 MHz ceramic was employed to detect the subharmonic acoustic emissions originating from the target position. In stage-1 experiments, we employed spectral analysis and performed an energy spectrum density (ESD) calculation. An optimized 0.55 MHz ESD level change was shown to effectively discriminate the occurrence of BBB-opening. Wideband acoustic emissions received from 0.55 MHz ceramics were also analyzed to evaluate its correlations with erythrocyte extravasations. In stage-2 real-time monitoring experiments, we applied the predetermined ESD change as a detection threshold in PC-controlled algorithm to predict the FUS exposure intra-operatively. In stage-1 experiment, we showed that subharmonic ESD presents distinguishable dynamics between intact BBB and opened BBB, and therefore a threshold ESD change level (5.5 dB) can be identified for BBB-opening prediction. Using this ESD change threshold detection as a

  6. Real-time monitoring of focused ultrasound blood-brain barrier opening via subharmonic acoustic emission detection: implementation of confocal dual-frequency piezoelectric transducers

    Tsai, Chih-Hung; Zhang, Jia-Wei; Liao, Yi-Yi; Liu, Hao-Li

    2016-01-01

    Burst-tone focused ultrasound exposure in the presence of microbubbles has been demonstrated to be effective at inducing temporal and local opening of the blood-brain barrier (BBB), which promises significant clinical potential to deliver therapeutic molecules into the central nervous system (CNS). Traditional contrast-enhanced imaging confirmation after focused ultrasound (FUS) exposure serves as a post-operative indicator of the effectiveness of FUS-BBB opening, however, an indicator that can concurrently report the BBB status and BBB-opening effectiveness is required to provide effective feedback to implement this treatment clinically. In this study, we demonstrate the use of subharmonic acoustic emission detection with implementation on a confocal dual-frequency piezoelectric ceramic structure to perform real-time monitoring of FUS-BBB opening. A confocal dual-frequency (0.55 MHz/1.1 MHz) focused ultrasound transducer was designed. The 1.1 MHz spherically-curved ceramic was employed to deliver FUS exposure to induce BBB-opening, whereas the outer-ring 0.55 MHz ceramic was employed to detect the subharmonic acoustic emissions originating from the target position. In stage-1 experiments, we employed spectral analysis and performed an energy spectrum density (ESD) calculation. An optimized 0.55 MHz ESD level change was shown to effectively discriminate the occurrence of BBB-opening. Wideband acoustic emissions received from 0.55 MHz ceramics were also analyzed to evaluate its correlations with erythrocyte extravasations. In stage-2 real-time monitoring experiments, we applied the predetermined ESD change as a detection threshold in PC-controlled algorithm to predict the FUS exposure intra-operatively. In stage-1 experiment, we showed that subharmonic ESD presents distinguishable dynamics between intact BBB and opened BBB, and therefore a threshold ESD change level (5.5 dB) can be identified for BBB-opening prediction. Using this ESD change threshold detection as a

  7. Engineering, design and prototype tests of a 3.9 GHz transverse-mode superconducting cavity for a radiofrequency-separated kaon beam

    Mark S. Champion et al.

    2001-01-01

    A research and development program is underway to construct superconducting cavities to be used for radiofrequency separation of a Kaon beam at Fermilab. The design calls for installation of twelve 13-cell cavities operating in the 3.9 GHz transverse mode with a deflection gradient of 5 MV/m. They present the mechanical, cryogenic and vacuum design of the cavity, cryomodule, rf power coupler, cold tuner and supporting hardware. The electromagnetic design of the cavity is presented in a companion paper by Wanzenberg and McAshan. The warm tuning system (for field flatness) and the vertical test system is presented along with test results of bench measurements and cold tests on single-cell and five-cell prototypes

  8. Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities

    Xu, Chen; Tantawi, Sami

    2016-02-01

    This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S(1 ,1 ) varying from 0 to -30 db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. The coupling mechanism to the cavity is also discussed.

  9. Conceptual design of a sapphire loaded coupler for superconducting radio-frequency 1.3 GHz cavities

    Chen Xu

    2016-02-01

    Full Text Available This paper explores a hybrid mode rf structure that served as a superconducting radio-frequency coupler. This application achieves a reflection S_{(1,1} varying from 0 to −30  db and delivers cw power at 7 KW. The coupler has good thermal isolation between the 2 and 300 K sections due to vacuum separation. Only one single hybrid mode can propagate through each section, and no higher order mode is coupled. The analytical and numerical analysis for this coupler is given and the design is optimized. The coupling mechanism to the cavity is also discussed.

  10. Design and commissioning of Fermilab's vertical test stand for ILC SRF cavities.

    Ozelis, Joseph P.; Carcagno, Ruben; Ginsburg, Camille M.; Huang, Yuenian; Norris, Barry; Peterson, Thomas; Poloubotko, Valeri; Rabehl, roger; Rakhno, Igor; Reid, Clark; Sergatskov, Dmitri A.; /Fermilab

    2007-06-01

    As part of its ILC program, Fermilab is developing a facility for vertical testing of SRF cavities. It operates at a nominal temperature of 2K, using a cryoplant that can supply LHe in excess of 20g/sec and provide bath pumping capacity of 125W at 2K. The below-grade cryostat consists of a vacuum vessel and LHe vessel, equipped with magnetic shielding to reduce the ambient magnetic field to <10mG. Internal fixed and external movable radiation shielding ensures that exposure to personnel is minimized. The facility features an integrated personnel safety system consisting of RF switches, interlocks, and area radiation monitors.

  11. Design and commissioning of Fermilab's vertical test stand for ILC SRF cavities

    Ozelis, Joseph P.; Carcagno, Ruben; Ginsburg, Camille M.; Huang, Yuenian; Norris, Barry; Peterson, Thomas; Poloubotko, Valeri; Rabehl, roger; Rakhno, Igor; Reid, Clark; Sergatskov, Dmitri A.

    2007-01-01

    As part of its ILC program, Fermilab is developing a facility for vertical testing of SRF cavities. It operates at a nominal temperature of 2K, using a cryoplant that can supply LHe in excess of 20g/sec and provide bath pumping capacity of 125W at 2K. The below-grade cryostat consists of a vacuum vessel and LHe vessel, equipped with magnetic shielding to reduce the ambient magnetic field to <10mG. Internal fixed and external movable radiation shielding ensures that exposure to personnel is minimized. The facility features an integrated personnel safety system consisting of RF switches, interlocks, and area radiation monitors

  12. Design of Transparent Anodes for Resonant Cavity Enhanced Light Harvesting in Organic Solar Cells

    Sergeant, Nicholas P.

    2012-01-03

    The use of an ITO-free MoO 3/Ag/MoO 3 anode to control the photon harvesting in PCDTBT:PC 70BM solar cells is proposed. At first sight, the fact that these anodes possess reduced far-field transmission compared to ITO may seem to be a disadvantage. But, despite this, we show that by carefully tuning the resonant optical cavity we can enhance the external quantum efficiency close to the band edge of PCDTBT, resulting in high photocurrent and power conversion efficiency on par with ITO. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Fracture behaviour of teeth with conventional and mini-invasive access cavity designs

    Chlup, Zdeněk; Žižka, R.; Kania, J.; Přibyl, M.

    2017-01-01

    Roč. 37, č. 14 (2017), s. 4423-4429 ISSN 0955-2219. [FAC 2016 - International Conference on Fractography of Advanced Ceramic s /5./. Smolenice, 09.10.2016-12.10.2016] R&D Projects: GA ČR GA14-11234S; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : endodontically treated premolars * in-vitro * maxillary premolars * stress-distribution * cusp coverage * resistance * composite * resin * restorations * scaffolds * Fracture resistance * Cavity * Tooth * Compressive test * Fractography Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass OBOR OECD: Ceramic s Impact factor: 3.411, year: 2016

  14. Electron diodes and cavity design for the new 4-MeV injector of the recirculating linear accelerator (RLA)

    Mazarakis, M.G.; Smith, D.L.; Poukey, J.W.; Bennett, L.F.; Olson, W.R.; Turman, B.N.

    1991-01-01

    The authors have designed and constructed four types of electron-beam diodes for the new 4-MV RLA injector: a non-immersed foilless diode, a magnetically immersed foilless diode, a foil diode and an ion-focused foilless diode, They are tailored to fit the new injector cavity. The design goals were to produce high quality 10-kA to 20-kA electron beams with a β perpendicular smaller than 0.2 and a beam radius of the order of 2 cm. These beams will be matched to the RLA IFR channel so β perpendicular must be equal to or smaller than the square root of the ratio of the beam current versus Alfven current for f e = 1. A reentrant anode geometry was selected for the injector cavity design, because it offers substantial savings on the required amount of feromagnetic cores. The inner radius of the outside shell, now only 30 cm, would have been twice as large (60 cm) if a coaxial non-reentrant geometry had been adopted. The shape of the anode and cathode electrodes were carefully selected to minimize the electric field stresses. The field stresses on the inner surface of the outer shell do not exceed 200 kV/cm

  15. Unified Subharmonic Oscillation Conditions for Peak or Average Current Mode Control

    Fang, Chung-Chieh

    2013-01-01

    This paper is an extension of the author's recent research in which only buck converters were analyzed. Similar analysis can be equally applied to other types of converters. In this paper, a unified model is proposed for buck, boost, and buck-boost converters under peak or average current mode control to predict the occurrence of subharmonic oscillation. Based on the unified model, the associated stability conditions are derived in closed forms. The same stability condition can be applied to ...

  16. Control of 3-D Modes in a Boundary Layer Undergoing Subharmonic Transition.

    Corke, T. C.; Peto, J.; Speer, A.; Paroozan, P.; Sciammarella, C.

    1997-11-01

    The effect of alternating standing patterns of wall displacements in the transition region of a Falkner-Skan boundary layer with an adverse pressure gradient is investigated. Transition is controlled by introducing disturbances to excite a pair of oblique modes along with a plane TS mode. The oblique modes are at the TS subharmonic frequency in order to promote subharmonic resonance. Measurements consist of a spanwise rake of hot-wire sensors placed near the wall below the critical layer, and a 2-D (15 x 15) array of optical pressure sensors. The space-time data series are processed using 2-D Fourier analysis to determine the spanwise wave number content of the flow. Of particular interest is the streamwise vortex mode which results from a difference interaction of the subharmonic oblique modes. We examine the effect of different patterns and amplitudes of upstream wall displacements on the development of the travelling and stationary modes in this case leading to transition. Supported by ARO Grant No. DAAH04-93-G-0212

  17. Even and odd subharmonic frequencies and chaos in Josephson junctions: Impact on parametric amplifiers

    Levinsen, M.T.

    1982-01-01

    The Stewart-McCumber model of a Josephson junction has been shown to exhibit period-doubling bifurcation cascades, as described by the Feigenbaum bifurcation theory. Chaotic states, sometimes associated with the bifurcations, are also prevalent. The present paper deals with the questions of subharmonic generation and chaotic states in the aforementioned model, and in addition with the problem of the ubiquitous noise rise found in Josephson junction parametric amplifiers. The bifurcation is first discussed by drawing on analytical results on the Duffing equation which is an approximation to the complete ac-driven Stewart-McCumber model. The complete model is then solved on an analog computer. Thereafter it is shown that besides the even subharmonics predicted by the bifurcation theory, the natural subharmonic to expect at small dc currents is the odd. This may then have associated its own bifurcation tree. The role of spontaneous symmetry breaking will be discussed. This reconciles the earlier treatment of the 3-photon amplifier with the Feigenbaum scheme. Finally, analog calculations on a model of an externally pumped Josephson junction parametric amplifier will be discussed. The conclusion seems to be that chaotic noise cannot account for the noise rise

  18. Evaluation and optimization of General Atomics' GT-MHR reactor cavity cooling system using an axiomatic design approach

    Thielman, Jeff; Ge, Ping; Wu, Qiao; Parme, Laurence

    2005-01-01

    The development of the Generation IV (Gen-IV) nuclear reactors has presented social, technical, and economical challenges to nuclear engineering design and research. To develop a robust, reliable nuclear reactor system with minimal environmental impact and cost, modularity has been gradually accepted as a key concept in designing high-quality nuclear reactor systems. While the establishment and reliability of a nuclear power plant is largely facilitated by the installment of standardized base units, the realization of modularity at the sub-system/sub-unit level in a base unit is still highly heuristic, and lacks consistent, quantifiable measures. In this work, an axiomatic design approach is developed to evaluate and optimize the reactor cavity cooling system (RCCS) of General Atomics' Gas Turbine-Modular Helium Reactor (GT-MHR) nuclear reactor, for the purpose of constructing a quantitative tool that is applicable to Gen-IV systems. According to Suh's axiomatic design theory, modularity is consistently represented by functional independence through the design process. Both qualitative and quantitative measures are developed here to evaluate the modularity of the current RCCS design. Optimization techniques are also used to improve the modularity at both conceptual and parametric level. The preliminary results of this study have demonstrated that the axiomatic design approach has great potential in enhancing modular design, and generating more robust, safer, and less expensive nuclear reactor sub-units

  19. Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

    Bai, Xianchen; Yang, Jianhua; Zhang, Jiande

    2012-08-01

    By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

  20. Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

    Bai Xianchen; Yang Jianhua; Zhang Jiande [College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2012-08-15

    By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

  1. Design and 3D simulation of a two-cavity wide-gap relativistic klystron amplifier with high power injection

    Bai Xianchen; Yang Jianhua; Zhang Jiande

    2012-01-01

    By using an electromagnetic particle-in-cell (PIC) code, an S-band two-cavity wide-gap klystron amplifier (WKA) loaded with washers/rods structure is designed and investigated for high power injection application. Influences of the washers/rods structure on the high frequency characteristics and the basic operation of the amplifier are presented. Generally, the rod structure has great impacts on the space-charge potential depression and the resonant frequency of the cavities. Nevertheless, if only the resonant frequency is tuned to the desired operation frequency, effects of the rod size on the basic operation of the amplifier are expected to be very weak. The 3-dimension (3-D) PIC simulation results show an output power of 0.98 GW corresponding to an efficiency of 33% for the WKA, with a 594 keV, 5 kA electron beam guided by an external magnetic field of 1.5 Tesla. Moreover, if a conductive plane is placed near the output gap, such as the electron collector, the beam potential energy can be further released, and the RF power can be increased to about 1.07 GW with the conversion efficiency of about 36%.

  2. Dental cavities

    ... this page: //medlineplus.gov/ency/article/001055.htm Dental cavities To use the sharing features on this page, please enable JavaScript. Dental cavities are holes (or structural damage) in the ...

  3. Design considerations and experimental observations for the TAMU air-cooled reactor cavity cooling system for the VHTR

    Sulaiman, S. A., E-mail: shamsulamri@tamu.edu; Dominguez-Ontiveros, E. E., E-mail: elvisdom@tamu.edu; Alhashimi, T., E-mail: jbudd123@tamu.edu; Budd, J. L., E-mail: dubaiboy@tamu.edu; Matos, M. D., E-mail: mailgoeshere@gmail.com; Hassan, Y. A., E-mail: yhasssan@tamu.edu [Department of Nuclear Engineering, Texas A and M University, College Station, TX, 77843-3133 (United States)

    2015-04-29

    The Reactor Cavity Cooling System (RCCS) is a promising passive decay heat removal system for the Very High Temperature Reactor (VHTR) to ensure reliability of the transfer of the core residual and decay heat to the environment under all off-normal circumstances. A small scale experimental test facility was constructed at Texas A and M University (TAMU) to study pertinent multifaceted thermal hydraulic phenomena in the air-cooled reactor cavity cooling system (RCCS) design based on the General Atomics (GA) concept for the Modular High Temperature Gas-Cooled Reactor (MHTGR). The TAMU Air-Cooled Experimental Test Facility is ⅛ scale from the proposed GA-MHTGR design. Groundwork for experimental investigations focusing into the complex turbulence mixing flow behavior inside the upper plenum is currently underway. The following paper illustrates some of the chief design considerations used in construction of the experimental test facility, complete with an outline of the planned instrumentation and data acquisition methods. Computational Fluid Dynamics (CFD) simulations were carried out to furnish some insights on the overall behavior of the air flow in the system. CFD simulations assisted the placement of the flow measurement sensors location. Preliminary experimental observations of experiments at 120oC inlet temperature suggested the presence of flow reversal for cases involving single active riser at both 5 m/s and 2.25 m/s, respectively and four active risers at 2.25 m/s. Flow reversal may lead to thermal stratification inside the upper plenum by means of steady state temperature measurements. A Particle Image Velocimetry (PIV) experiment was carried out to furnish some insight on flow patterns and directions.

  4. Design and Analysis of Enhanced Modulation Response in Integrated Coupled Cavities DBR Lasers Using Photon-Photon Resonance

    Paolo Bardella

    2016-01-01

    Full Text Available In the last few decades, various solutions have been proposed to increase the modulation bandwidth and, consequently, the transmission bit-rate of semiconductor lasers. In this manuscript, we discuss a design procedure for a recently proposed laser cavity realized with the monolithic integration of two distributed Bragg reflector (DBR lasers allowing one to extend the modulation bandwidth. Such an extension is obtained introducing in the dynamic response a photon-photon resonance (PPR at a frequency higher than the modulation bandwidth of the corresponding single-section laser. Design guidelines will be proposed, and dynamic small and large signal simulations results, calculated using a finite difference traveling wave (FDTW numerical simulator, will be discussed to confirm the design results. The effectiveness of the design procedure is verified in a structure with PPR frequency at 35 GHz allowing one to obtain an open eye diagram for a non-return-to-zero (NRZ digital signal up to 80 GHz . Furthermore, the investigation of the rich dynamics of this structure shows that with proper bias conditions, it is possible to obtain also a tunable self-pulsating signal in a frequency range related to the PPR design.

  5. Performance characterisation of a passive cavitation detector optimised for subharmonic periodic shock waves from acoustic cavitation in MHz and sub-MHz ultrasound.

    Johansen, Kristoffer; Song, Jae Hee; Prentice, Paul

    2018-05-01

    We describe the design, construction and characterisation of a broadband passive cavitation detector, with the specific aim of detecting low frequency components of periodic shock waves, with high sensitivity. A finite element model is used to guide selection of matching and backing layers for the shock wave passive cavitation detector (swPCD), and the performance is evaluated against a commercially available device. Validation of the model, and characterisation of the swPCD is achieved through experimental detection of laser-plasma bubble collapse shock waves. The final swPCD design is 20 dB more sensitive to the subharmonic component, from acoustic cavitation driven at 220 kHz, than the comparable commercial device. This work may be significant for monitoring cavitation in medical applications, where sensitive detection is critical, and higher frequencies are more readily absorbed by tissue. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Enhanced direct-modulated bandwidth of 37 GHz by a multi-section laser with a coupled-cavity-injection-grating design

    Bach, L.; Kaiser, W.; Reithmaier, J.P.

    2003-01-01

    Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device.......Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device....

  7. Design and Fabrication of 850 and 980 nm Vertical Cavity Surface Emitting Laser

    Das, N

    2004-01-01

    .... VCSELs on GaAs substrates were grown by the molecular beam epitaxy technique. In this report we present detailed procedures to design and fabricate 850-nm top-emitting and 980-nm bottom-emitting VCSELs...

  8. Thermal coupling and effect of subharmonic synchronization in a system of two VO2 based oscillators

    Velichko, Andrey; Belyaev, Maksim; Putrolaynen, Vadim; Perminov, Valentin; Pergament, Alexander

    2018-03-01

    We explore a prototype of an oscillatory neural network (ONN) based on vanadium dioxide switching devices. The model system under study represents two oscillators based on thermally coupled VO2 switches. Numerical simulation shows that the effective action radius RTC of coupling depends both on the total energy released during switching and on the average power. It is experimentally and numerically proved that the temperature change ΔT commences almost synchronously with the released power peak and T-coupling reveals itself up to a frequency of about 10 kHz. For the studied switching structure configuration, the RTC value varies over a wide range from 4 to 45 μm, depending on the external circuit capacitance C and resistance Ri, but the variation of Ri is more promising from the practical viewpoint. In the case of a "weak" coupling, synchronization is accompanied by attraction effect and decrease of the main spectra harmonics width. In the case of a "strong" coupling, the number of effects increases, synchronization can occur on subharmonics resulting in multilevel stable synchronization of two oscillators. An advanced algorithm for synchronization efficiency and subharmonic ratio calculation is proposed. It is shown that of the two oscillators the leading one is that with a higher main frequency, and, in addition, the frequency stabilization effect is observed. Also, in the case of a strong thermal coupling, the limit of the supply current parameters, for which the oscillations exist, expands by ∼10%. The obtained results have a universal character and open up a new kind of coupling in ONNs, namely, T-coupling, which allows for easy transition from 2D to 3D integration. The effect of subharmonic synchronization hold promise for application in classification and pattern recognition.

  9. Non-equilibrium coherent vortex states and subharmonic giant Shapiro steps in Josephson junction arrays

    Dominguez, D.; Jose, J.V.; Northeastern Univ., Boston, MA

    1994-01-01

    This is a review of recent work on the dynamic response of Josephson junction arrays driven by dc and ac currents. The arrays are modeled by the resistively shunted Josephson junction model, appropriate for proximity effect junctions, including self-induced magnetic fields as well as disorder. The relevance of the self-induced fields is measured as a function of a parameter κ = λ L /a, with λ L the London penetration depth of the arrays, and a the lattice spacing. The transition from Type II (κ > 1) to Type I (κ < 1) behavior is studied in detail. The authors compare the results for models with self, self + nearest-neighbor, and full inductance matrices. In the κ = ∞ limit, they find that when the initial state has at least one vortex-antivortex pair, after a characteristic transient time these vortices unbind and radiate other vortices. These radiated vortices settle into a parity-broken, time-periodic, axisymmetric coherent vortex state (ACVS), characterized by alternate rows of positive and negative vortices lying along a tilted axis. The ACVS produces subharmonic steps in the current voltage (IV) characteristics, typical of giant Shapiro steps. For finite κ they find that the IV's show subharmonic giant Shapiro steps, even at zero external magnetic field. They find that these subharmonic steps are produced by a whole family of coherent vortex oscillating patterns, with their structure changing as a function of κ. In general, they find that these patterns are due to a breakdown of translational invariance produced, for example, by disorder of antisymmetric edge-fields. The zero field case results are in good qualitative agreement with experiments in Nb-Au-Nb arrays

  10. Optimization of photonic crystal cavities

    Wang, Fengwen; Sigmund, Ole

    2017-01-01

    We present optimization of photonic crystal cavities. The optimization problem is formulated to maximize the Purcell factor of a photonic crystal cavity. Both topology optimization and air-hole-based shape optimization are utilized for the design process. Numerical results demonstrate...... that the Purcell factor of the photonic crystal cavity can be significantly improved through optimization....

  11. Frequency locking, quasiperiodicity, subharmonic bifurcations and chaos in high frequency modulated stripe geometry DH semiconductor lasers

    Zhao Yiguang

    1991-01-01

    The method of obtaining self-consistent solutions of the field equation and the rate equations of photon density and carrier concentration has been used to study frequecny locking, quasiperiodicity, subharmonic bifurcations and chaos in high frequency modulated stripe geometry DH semiconductor lasers. The results show that the chaotic behavior arises in self-pulsing stripe geometry semiconductor lasers. The route to chaos is not period-double, but quasiperiodicity to chaos. All of the results agree with the experiments. Some obscure points in previous theory about chaos have been cleared up

  12. Controlling chaos in a pendulum equation with ultra-subharmonic resonances

    Yang Jianping; Jing Zhujun

    2009-01-01

    Analytical and numerical results concerning control of chaos in a pendulum equation with parametric and external excitations are given by using Melnikov methods. We give the necessary conditions of chaos control with ultra-subharmonic resonances (i.e. Ω/ω=p/q,q>1,p,q are prime), where homoclinic chaos or heteroclinic chaos can be inhibited. Numerical simulations show that chaotic behavior can be converted to period-nq (n element of Z + ) orbits by adjusting amplitude and phase-difference of parametric excitation, and the distribution of maximum Lyapunov exponents in parameter-plane (Ψ,β) gives the regions in which chaos can be controlled.

  13. Design and Measurements of an X-Band Accelerating Cavity for SPARC

    Alesini, David; Falone, Antonio; Ferrario, Massimo; Migliorati, Mauro; Mostacci, Andrea; Palpini, Federica; Palumbo, Luigi; Spataro, Bruno

    2005-01-01

    The paper presents the design of an X-band accelerating section for linearizing the longitudinal phase space in the Frascati Linac Coherent Light Source (SPARC). The structure, operating on the pi standing wave mode, is a 9 cells structure feeded by a central waveguide coupler and has been designed to obtain a 5 MV accelerating voltage. The 2D profile has been obtained using the e.m. codes SUPERFISH and OSCARD2D while the coupler has been designed using HFSS. Bead-pull measurement made on a copper prototype are illustrated and compared with the numerical results. Mechanical details of the realized prototype and RF properties of the structure as a function of the assembly characteristics are also discussed.

  14. Optical and mechanical design of a "zipper" photonic crystal optomechanical cavity.

    Chan, Jasper; Eichenfield, Matt; Camacho, Ryan; Painter, Oskar

    2009-03-02

    Design of a doubly-clamped beam structure capable of localizing mechanical and optical energy at the nanoscale is presented. The optical design is based upon photonic crystal concepts in which patterning of a nanoscale-cross-section beam can result in strong optical localization to an effective optical mode volume of 0.2 cubic wavelengths ( (lambdac)(3)). By placing two identical nanobeams within the near field of each other, strong optomechanical coupling can be realized for differential motion between the beams. Current designs for thin film silicon nitride beams at a wavelength of lambda?= 1.5 microm indicate that such structures can simultaneously realize an optical Q-factor of 7x10(6), motional mass m(u) approximately 40 picograms, mechanical mode frequency Omega(M)/2pi approximately 170 MHz, and an optomechanical coupling factor (g(OM) identical with domega(c)/dx = omega(c)/L(OM)) with effective length L(OM) approximately lambda= 1.5 microm.

  15. Crab cavities for linear colliders

    Burt, G; Carter, R; Dexter, A; Tahir, I; Beard, C; Dykes, M; Goudket, P; Kalinin, A; Ma, L; McIntosh, P; Shulte, D; Jones, Roger M; Bellantoni, L; Chase, B; Church, M; Khabouline, T; Latina, A; Adolphsen, C; Li, Z; Seryi, Andrei; Xiao, L

    2008-01-01

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  16. A compact D-band monolithic APDP-based sub-harmonic mixer

    Zhang, Shengzhou; Sun, Lingling; Wang, Xiang; Wen, Jincai; Liu, Jun

    2017-11-01

    The paper presents a compact D-band monolithic sub-harmonic mixer (SHM) with 3 μm planar hyperabrupt schottky-varactor diodes offered by 70 nm GaAs mHEMT technology. According to empirical equivalent-circuit models, a wide-band large signal equivalent circuit model of the diode is proposed. Based on the extracted model, the mixer is implemented and optimized with a shunt-mounted anti-parallel diode pair (APDP) to fulfill the sub-harmonic mixing mechanism. Furthermore, a modified asymmetric three-transmission-line coupler is devised to achieve high-level coupling and minimize the chip size. The measured results show that the conversion gain varies between -13.9 dB and -17.5 dB from 110 GHz to 145 GHz, with a local oscillator (LO) power level of 14 dBm and an intermediate frequency (IF) of 1 GHz. The total chip size including probe GSG pads is 0.57 × 0.68mm2. In conclusion, the mixer exhibits outstanding figure-of-merits.

  17. Subharmonics and noise excitation in transmission of acoustic wave through unconsolidated granular medium

    Tournat, V.; Gusev, V.E.; Castagnede, B.

    2004-01-01

    First laboratory-scale experimental observation of both subharmonics excitation and significant increase in noise level caused by propagation of the acoustic wave in unconsolidated granular material is reported. The bifurcation phenomenon, taking place above a critical level of acoustic excitation (and opening the subharmonics route to chaos) is attributed to the interaction of acoustic wave with distributed system of highly nonlinear inter-grain contacts. The estimates demonstrated that these are weak contacts (loaded at least two orders of magnitude weaker than in average) that might be responsible for the observed nonlinear effects. The additional intermittent contacts created by the acoustic wave (which are open in the absence of acoustic loading) can also contribute. In the clapping (tapping) regime, each of these contacts individually is similar to an impact oscillator, for which the scenario of period doubling cascade and the transition to chaotic behavior has been predicted theoretically and observed experimentally earlier. The experiments confirm that the nonlinear interactions of acoustic waves in granular assemblages are highly sensitive to the fraction of weakly loaded (and unloaded) contacts, information on which is difficult to access by any other experimental methods

  18. Electron beam sub-harmonics chopping system for linear accelerator injector

    Bourat, Christophe

    1988-01-01

    The need of a 100 % duty cycle electron accelerator for use in nuclear physics, has led in 1981 the CEN Saclay Linear Accelerator Group, to study a machine using the existing linac associated with a pulse stretcher ring. The production of electron bunches at the ring RF frequency (600 MHz) requires the design of a new injector including a chopping beam System with a deflecting electromagnetic cavity and a collimator. A comparison between four transverse magnetic modes, led to choose a TM110 parallelepiped chopper. The construction of a prototype and of a vacuum-tight cavity followed by microwave measurements has permitted to solve several mechanical problems and to specify the cavity electrical properties. In a first step, the beam line, including - focusing, offset deflection coils, chopping with a rectangular collimator - has been studied, for zero intensity beam current, on the basis of a matrix model. An experimental 40 keV beam line, has been assembled to measure the bunch length. The method was based on a spectral analysis of the signal delivered by a large band, 50 ohms adapted beam collector. The bunch shape in the time domain was reconstructed by inverse Fourier transform. The beam dynamics has been studied with a 3D space charge model which has been introduced into the PARMELA tracking code. Simulations showed that a 150 keV, 2 A beam could be chopped with the same deflecting lay-out. (author) [fr

  19. Noninvasive Ambient Pressure Estimation using Ultrasound Contrast Agents -- Invoking Subharmonics for Cardiac and Hepatic Applications

    Dave, Jaydev K.

    Ultrasound contrast agents (UCAs) are encapsulated microbubbles that provide a source for acoustic impedance mismatch with the blood, due to difference in compressibility between the gas contained within these microbubbles and the blood. When insonified by an ultrasound beam, these UCAs act as nonlinear scatterers and enhance the echoes of the incident pulse, resulting in scattering of the incident ultrasound beam and emission of fundamental (f0), subharmonic (f0/2), harmonic (n*f0; n ∈ N) and ultraharmonic (((2n-1)/2)*f0; n ∈ N & n > 1) components in the echo response. A promising approach to monitor in vivo pressures revolves around the fact that the ultrasound transmit and receive parameters can be selected to induce an ambient pressure amplitude dependent subharmonic signal. This subharmonic signal may be used to estimate ambient pressure amplitude; such technique of estimating ambient pressure amplitude is referred to as subharmonic aided pressure estimation or SHAPE. This project develops and evaluates the feasibility of SHAPE to noninvasively monitor cardiac and hepatic pressures (using commercially available ultrasound scanners and UCAs) because invasive catheter based pressure measurements are used currently for these applications. Invasive catheter based pressure measurements pose risk of introducing infection while the catheter is guided towards the region of interest in the body through a percutaneous incision, pose risk of death due to structural or mechanical failure of the catheter (which has also triggered product recalls by the USA Food and Drug Administration) and may potentially modulate the pressures that are being measured. Also, catheterization procedures require fluoroscopic guidance to advance the catheter to the site of pressure measurements and such catheterization procedures are not performed in all clinical centers. Thus, a noninvasive technique to obtain ambient pressure values without the catheterization process is clinically

  20. Superconducting TESLA cavities

    B. Aune

    2000-09-01

    Full Text Available The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of E_{acc}≥25 MV/m at a quality factor Q_{0}≥5×10^{9}. The design goal for the cavities of the TESLA Test Facility (TTF linac was set to the more moderate value of E_{acc}≥15 MV/m. In a first series of 27 industrially produced TTF cavities the average gradient at Q_{0}=5×10^{9} was measured to be 20.1±6.2 MV/m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q_{0}=5×10^{9} amounts to 25.0±3.2 MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.

  1. Design, Construction, and Initial Test of High Spatial Resolution Thermometry Arrays for Detection of Surface Temperature Profiles on SRF Cavities in Super Fluid Helium

    Ari Palczewski, Rongli Geng, Grigory Eremeev

    2011-07-01

    We designed and built two high resolution (0.6-0.55mm special resolution [1.1-1.2mm separation]) thermometry arrays prototypes out of the Allen Bradley 90-120 ohm 1/8 watt resistor to measure surface temperature profiles on SRF cavities. One array was designed to be physically flexible and conform to any location on a SRF cavity; the other was modeled after the common G-10/stycast 2850 thermometer and designed to fit on the equator of an ILC (Tesla 1.3GHz) SRF cavity. We will discuss the advantages and disadvantages of each array and their construction. In addition we will present a case study of the arrays performance on a real SRF cavity TB9NR001. TB9NR001 presented a unique opportunity to test the performance of each array as it contained a dual (4mm separation) cat eye defect which conventional methods such as OST (Oscillating Superleak second-sound Transducers) and full coverage thermometry mapping were unable to distinguish between. We will discuss the new arrays ability to distinguish between the two defects and their preheating performance.

  2. Influence of Cavity Margin Design and Restorative Material on Marginal Quality and Seal of Extended Class II Resin Composite Restorations In Vitro.

    Soliman, Sebastian; Preidl, Reinhard; Karl, Sabine; Hofmann, Norbert; Krastl, Gabriel; Klaiber, Bernd

    2016-01-01

    To investigate the influence of three cavity designs on the marginal seal of large Class II cavities restored with low-shrinkage resin composite limited to the enamel. One hundred twenty (120) intact human molars were randomly divided into 12 groups, with three different cavity designs: 1. undermined enamel, 2. box-shaped, and 3. proximal bevel. The teeth were restored with 1. an extra-low shrinkage (ELS) composite free of diluent monomers, 2. microhybrid composite (Herculite XRV), 3. nanohybrid composite (Filtek Supreme XTE), and 4. silorane-based composite (Filtek Silorane). After artificial aging by thermocycling and storage in physiological saline, epoxy resin replicas were prepared. To determine the integrity of the restorations' approximal margins, two methods were sequentially employed: 1. replicas were made of the 120 specimens and examined using SEM, and 2. the same 120 specimens were immersed in AgNO3 solution, and the dye penetration depth was observed with a light microscope. Statistical analysis was performed using the Kruskal-Wallis and the Dunn-Bonferroni tests. After bevel preparation, SEM observations showed that restorations did not exhibit a higher percentage of continuous margin (SEM-analysis; p>0.05), but more leakage was found than with the other cavity designs (pcomposite restorations and is no longer recommended. However, undermined enamel should be removed to prevent enamel fractures.

  3. A 38 to 44GHz sub-harmonic balanced HBT mixer with integrated miniature spiral type marchand balun

    Johansen, Tom Keinicke; Krozer, Viktor

    2013-01-01

    This work presents an active balanced sub-harmonic mixer (SHM) using InP double heterojunction bipolar transistor technology (DHBT) for Q-band applications. A miniature spiral type Marchand balun with five added capacitances for improved control of amplitude and phase balance is integrated with t...

  4. Subharmonic Venture

    T. Faez (Telli)

    2012-01-01

    textabstractAs a person, always fascinated with the presence of physics in the daily life challenges, let me share this joy with you! But before leaving you with complicated medical terms, allow me to tell you a story. My grandmother passed away when I was nine years old. She was the sweetest

  5. accelerating cavity

    On the inside of the cavity there is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  6. A Clinical Evaluation of Deproteinization and Different Cavity Designs on Resin Restoration Performance in MIH-Affected Molars: Two-Year Results.

    Sönmez, Hayriye; Saat, Sinem

    The aim of this study was to evaluate the clinical effects of deproteinization of the hypomineralized enamel and different cavity designs on the performance of the composite resin restorations(CRRs) placed into the cavities of MIH (molar incisor hypomineralization)-affected molars. 95 MIH-affected permanent first molars (PFMs) and 31 caries but not MIH-affected PFMs (126 teeth in total) were included in the study. The MIH-affected molars were divided into three groups. In Group I, all hypomineralized tissue was removed until healthy enamel was reached. In Group II, carious and cheesy hypomineralized tissue was removed until a reasonable resistance was detected in the hypomineralized tissue. In Group III, cavities designed as Group II, differently from this group deproteinization of the left hypomineralized tissue was performed prior to the placement of CRRs. Group IV served as the control group consisting of unaffected carious PFMs. Restorations were evaluated according to modified USPHS criteria for 24 months. The retention rates were 93.7% for Group I, 80.7% for Group II, 93.5% for Group III and 100% for Group IV. The success rate for the restorations in Group II proved significantly lower (p0.05) at the end of 24 months. Failure of the restorations was predominant in the group that the hypomineralized tissue was left surrounding the cavities. Deproteinization of the hypomineralized enamel was found to enhance the retention rates of CRRs.

  7. radiofrequency cavity

    1988-01-01

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  8. Fundamental and Subharmonic Resonances of Harmonically Oscillation with Time Delay State Feedback

    A.F. EL-Bassiouny

    2006-01-01

    Full Text Available Time delays occur in many physical systems. In particular, when automatic control is used with structural or mechanical systems, there exists a delay between measurement of the system state and corrective action. The concept of an equivalent damping related to the delay feedback is proposed and the appropriate choice of the feedback gains and the time delay is discussed from the viewpoint of vibration control. We investigate the fundamental resonance and subharmonic resonance of order one-half of a harmonically oscillation under state feedback control with a time delay. By using the multiple scale perturbation technique, the first order approximation of the resonances are derived and the effect of time delay on the resonances is investigated. The fixed points correspond to a periodic motion for the starting system and we show the external excitation-response and frequency-response curves. We analyze the effect of time delay and the other different parameters on these oscillations.

  9. Nonlinear Response of Vibrational Conveyers with Nonideal Vibration Exciter: Superharmonic and Subharmonic Resonance

    H. Bayıroğlu

    2012-01-01

    Full Text Available Vibrational conveyers with a centrifugal vibration exciter transmit their load based on the jumping method. Common unbalanced-mass driver oscillates the trough. The motion is strictly related to the vibrational parameters. The transition over resonance of a vibratory system, excited by rotating unbalances, is important in terms of the maximum vibrational amplitude produced and the power demand on the drive for the crossover. The mechanical system is driven by the DC motor. In this study, the working ranges of oscillating shaking conveyers with nonideal vibration exciter have been analyzed analytically for superharmonic and subharmonic resonances by the method of multiple scales and numerically. The analytical results obtained in this study agree well with the numerical results.

  10. Phase characteristics of solid-state amplifiers in sub-harmonic bunchers

    Liu Rong; Ma Xinpeng; Zhao Fengli; Wang Xiangjian; Wang Guangwei; Huang Yongqing; Zhang Donghui

    2009-01-01

    To study the phase characteristics of solid-state amplifiers(20 kW/142.8 MHz,10 kW/571.2 MHz) in sub-harmonic bunchers(SHBs) of the BEPC II linear accelerator, phase shift in pulse and phase stability are measured using a digital measurement method based on field programmable gate array(FPGA). The hardware of the measurement system includes the frequency synthesizer, digital signal processing board(FPGA) and PC, and the software includes an internal algorithm on FPGA, communication procedures and PC client interface procedures. The measurement results of phase characteristics are consistent with the actual situation, which is the basis for the further implement of phase compensation in SHBs. (authors)

  11. Design and simulation of 3½-cell superconducting gun cavity and beam dynamics studies of the SASE-FEL System at the Institute of Accelerator Technologies at Ankara University

    Yildiz, H. Duran; Cakir, R.; Porsuk, D.

    2015-01-01

    Design and simulation of a superconducting gun cavity with 3½ cells have been studied in order to give the first push to the electron beam for the linear accelerating system at The Institute of Accelerator Technologies at Ankara University. Electrons are accelerated through the gun cavity with the help of the Radiofrequency power suppliers from cryogenic systems. Accelerating gradient should be as high as possible to accelerate electron beam inside the cavity. In this study, electron beam reaches to 9.17 MeV energy at the end of the gun cavity with the accelerating gradient; E c =19.21 MV/m. 1.3 GHz gun cavity consists of three TESLA-like shaped cells while the special designed gun-cell includes a cathode plug. Optimized important beam parameters inside the gun cavity, average beam current 3 mA, transverse emittance 2.5 mm mrad, repetition rate 30 MHz and other parameters are obtained for the SASE-FEL System. The Superfish/Poisson program is used to design each cell of the superconducting cavity. Superconducting gun cavity and Radiofrequency properties are studied by utilizing 2D Superfish/Poisson, 3D Computer Simulation Technology Microwave Studio, and 3D Computer Simulation Technology Particle Studio. Superfish/Poisson is also used to optimize the geometry of the cavity cells to get the highest accelerating gradient. The behavior of the particles along the beamline is included in this study. ASTRA Code is used to track the particles

  12. Design and simulation of 3½-cell superconducting gun cavity and beam dynamics studies of the SASE-FEL System at the Institute of Accelerator Technologies at Ankara University

    Yildiz, H. Duran, E-mail: hdyildiz@ankara.edu.tr [Institute of Accelerator Technologies, Ankara University, Ankara (Turkey); Cakir, R. [Nanotechnology Engineering Department, Recep Tayyip Erdogan University, Rize (Turkey); Porsuk, D. [Physics Department, Dumlupinar University, Kutahya (Turkey)

    2015-06-11

    Design and simulation of a superconducting gun cavity with 3½ cells have been studied in order to give the first push to the electron beam for the linear accelerating system at The Institute of Accelerator Technologies at Ankara University. Electrons are accelerated through the gun cavity with the help of the Radiofrequency power suppliers from cryogenic systems. Accelerating gradient should be as high as possible to accelerate electron beam inside the cavity. In this study, electron beam reaches to 9.17 MeV energy at the end of the gun cavity with the accelerating gradient; E{sub c}=19.21 MV/m. 1.3 GHz gun cavity consists of three TESLA-like shaped cells while the special designed gun-cell includes a cathode plug. Optimized important beam parameters inside the gun cavity, average beam current 3 mA, transverse emittance 2.5 mm mrad, repetition rate 30 MHz and other parameters are obtained for the SASE-FEL System. The Superfish/Poisson program is used to design each cell of the superconducting cavity. Superconducting gun cavity and Radiofrequency properties are studied by utilizing 2D Superfish/Poisson, 3D Computer Simulation Technology Microwave Studio, and 3D Computer Simulation Technology Particle Studio. Superfish/Poisson is also used to optimize the geometry of the cavity cells to get the highest accelerating gradient. The behavior of the particles along the beamline is included in this study. ASTRA Code is used to track the particles.

  13. Opto-mechanical design of a buckling cavity in a novel high-performance outside-plant robust field installable single-mode fibre connector

    Ebraert, Evert; Van Erps, Jürgen; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2014-05-01

    Fibre-to-the-home (FTTH) networks provide an ideal means to reach the goal the European Union has set to provide 50 % of the households with a broadband connection faster than 100 Mb/s. Deployment of FTTH networks, which is still costly today, could be significantly boosted by novel ferrule-less connectors which don't require highly skilled personnel and allow installation in the field. We propose a ferrule-less connector in which two single-mode fibres (SMFs) are aligned and maintain physical contact by ensuring that at least one fibre is in a buckled state. To this end, we design a cavity in which a fibre can buckle in a controlled way. Using finite element analysis simulations to investigate the shape of the formed buckle for various buckling cavity lengths, we show that it can be accurately approximated by a cosine function. In addition, the optical performance of a buckled SMF is investigated by bending loss calculations and simulations. We show a good agreement between the analytical and the simulated bending loss results for a G.652 fibre at a wavelength of 1550 nm. Buckling cavity lengths smaller than 20 mm should be avoided to keep the optical bending loss due to buckling below 0.1 dB. In this case the cavity height should at least be 2 mm to avoid mechanical confinement of the fibre.

  14. Normal Conducting RF Cavity for MICE

    Li, D.; DeMello, A.; Virostek, S.; Zisman, M.; Summers, D.

    2010-01-01

    Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.

  15. Design of a Novel Polarized Beam Splitter Based on a Two-Dimensional Photonic Crystal Resonator Cavity

    Zhang Xuan; Chen Shu-Wen; Liao Qing-Hua; Yu Tian-Bao; Liu Nian-Hua; Huang Yong-Zhen

    2011-01-01

    We propose and analyze a novel ultra-compact polarization beam splitter based on a resonator cavity in a two-dimensional photonic crystal. The two polarizations can be separated efficiently by the strong coupling between the microcavities and the waveguides occurring around the resonant frequency of the cavities. The transmittance of two polarized light around 1.55 μm can be more than 98.6%, and the size of the device is less than 15 μm×13 μm, so these features will play an important role in future integrated optical circuits. (fundamental areas of phenomenology(including applications))

  16. The Superconducting TESLA Cavities

    Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.

    2000-01-01

    The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...

  17. Cryostat for TRISTAN superconducting cavity

    Mitsunobu, S.; Furuya, T.; Hara, K.

    1990-01-01

    Superconducting cavities generate rather high heat load of hundreds watts in one cryostat and have high sensitivity for pressure. We adopted usual pool-boiling type cooling for its stable pressure operation. Two 5-cell Nb cavities were installed in one flange type cryostat. Tuning mechanics actuated by a pulse-motor and a Piezo-electric element are set at outside of vacuum end flange. The design and performance of the cryostat for TRISTAN superconducting cavities are described. (author)

  18. The design and performance of a water cooling system for a prototype coupled cavity linear particle accelerator for the spallation neutron source

    Bernardin, John D.; Ammerman, Curtt N.; Hopkins, Steve M.

    2002-01-01

    The Spallation Neutron Source (SNS) is a facility being designed for scientific and industrial research and development. The SNS will generate and employ neutrons as a research tool in a variety of disciplines including biology, material science, superconductivity, chemistry, etc. The neutrons will be produced by bombarding a heavy metal target with a high-energy beam of protons, generated and accelerated with a linear particle accelerator, or linac. The low energy end of the linac consists of, in part, a multi-cell copper structure termed a coupled cavity linac (CCL). The CCL is responsible for accelerating the protons from an energy of 87 MeV, to 185 MeV. Acceleration of the charged protons is achieved by the use of large electrical field gradients established within specially designed contoured cavities of the CCL. While a large amount of the electrical energy is used to accelerate the protons, approximately 60-80% of this electrical energy is dissipated in the CCL's copper structure. To maintain an acceptable operating temperature, as well as minimize thermal stresses and maintain desired contours of the accelerator cavities, the electrical waste heat must be removed from the CCL structure. This is done using specially designed water cooling passages within the linac's copper structure. Cooling water is supplied to these cooling passages by a complex water cooling and temperature control system. This paper discusses the design, analysis, and testing of a water cooling system for a prototype CCL. First, the design concept and method of water temperature control is discussed. Second, the layout of the prototype water cooling system, including the selection of plumbing components, instrumentation, as well as controller hardware and software is presented. Next, the development of a numerical network model used to size the pump, heat exchanger, and plumbing equipment, is discussed. Finally, empirical pressure, flow rate, and temperature data from the prototype CCL

  19. Fourier series and δ-subharmonic functions of finite γ-type in a half-plane

    Malyutin, K G

    2001-01-01

    Let γ(r) be a growth function and let v(z) be a proper δ-subharmonic function in the sense of Grishin in a complex half-plane, that is v=v 1 -v 2 , where v 1 and v 2 are proper subharmonic functions (limsup z→t v i (z)≤0, for each real t, i=1,2), let λ=λ + -λ - be the full measure corresponding to v and let T(r,v) be its Nevanlinna characteristic. The class Jδ(γ) of functions of finite γ-type is defined as follows: v element of Jδ(γ) if T(r,v)≤Aγ(Br)/r for some positive constants A and B. The Fourier coefficients of v are defined in the standard way. The central result of the paper is the equivalence of the following properties: (1) v element of Jδ(γ); (2) N(r)≤A 1 γ(B 1 r)/r, where N(r)=N(r,λ + ) or N(r)=N(r,λ - ), and |c k (r,v)|≤A 2 γ(B 2 r). It is proved in addition that Jδ(γ)=JS(γ)-JS(γ), where JS(γ) is the class of proper subharmonic functions of finite γ-type

  20. Design of a high speed, high resolution thermometry system for 1.5 GHz superconducting radio frequency cavities

    Knobloch, Jens; Muller, Henry; Padamsee, Hasan

    1994-11-01

    Presented in this paper are the description and the test results of a new stationary thermometry system used to map the temperature of the outer surface of 1.5 GHz superconducting single-cell cavities during operation at 1.6 K. The system comprises 764 removable carbon thermometers whose signals are multiplexed and scanned by a Macintosh computer. A complete temperature map can be obtained in as little as 0.1 s at a temperature resolution of about 0.2 mK. Alternatively, it has been demonstrated that if the acquisition time is increased to several seconds, then a temperature resolution on the order of 30 μK is possible. To our knowledge, these are the fastest acquisition times so far achieved with L-band cavities at these resolutions.

  1. Single and Coupled Nanobeam Cavities

    Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Shyroki, Dzmitry M.

    2013-01-01

    for analysis and design of photonic crystal devices, such as 2D ring resonators for filters, single and coupled nanobeam cavities, birefringence in photonic crystal cavities, threshold analysis in photonic crystal lasers, gap solitons in photonic crystals, novel photonic atolls, dynamic characteristics...

  2. Superconducting elliptical cavities

    Sekutowicz, J K

    2011-01-01

    We give a brief overview of the history, state of the art, and future for elliptical superconducting cavities. Principles of the cell shape optimization, criteria for multi-cell structures design, HOM damping schemes and other features are discussed along with examples of superconducting structures for various applications.

  3. Temperature evolution of subharmonic gap structures in MgB{sub 2}/Nb point-contacts

    Giubileo, F. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy)], E-mail: giubileo@sa.infn.it; Bobba, F.; Scarfato, A.; Piano, S. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy); Aprili, M. [Laboratoire de Spectroscopie en Lumiere Polarisee, ESPCI, 10 rue Vauquelin, 75005 Paris (France); CSNSM-CNRS, Bat. 108 Universite Paris-Sud, 91405 Orsay (France); Cucolo, A.M. [CNR-INFM Laboratorio Regionale SUPERMAT e Dipartimento di Fisica ' E.R. Caianiello' , Universita degli Studi di Salerno, via Salvador Allende, 84081 Baronissi (Italy)

    2007-09-01

    We have performed point-contact spectroscopy experiments on superconducting micro-constrictions between Nb tips and high quality MgB{sub 2} pellets. We measured the temperature evolution (between 4.2 K and 300 K) of the current-voltage (I-V) and of the dynamical conductance (dI/dV-V) characteristics. Above the Nb critical temperature T{sub C}{sup Nb}, the conductance of the constrictions behaves as predicted by the BTK model for S/N contacts being Nb in its normal state below T{sub C}{sup Nb}, the contacts show Josephson current and subharmonic gap structures, due to multiple Andreev reflections. These observations clearly indicate the coupling of the MgB{sub 2} 3D {pi}-band with the Nb superconducting order parameter. We found {delta}{sub {pi}} = 2.4 {+-} 0.2 meV for the three-dimensional gap of MgB{sub 2}.

  4. Superconducting cavities for HERA

    Dwersteg, B.; Ebeling, W.; Moeller, W.D.; Renken, D.; Proch, D.; Sekutowicz, J.; Susta, J.; Tong, D.

    1988-01-01

    Superconducting 500 MHz cavities are developed to demonstrate the feasibility of upgrading the e-beam energy of the HERA storage ring. A prototype module with 2 x 4 cell resonators and appropriate fundamental and higher mode couplers has been designed at DESY and is being built by industrial firms. The design and results of RF and cryogenic measurements are reported in detail. 17 references, 10 figures, 2 tables

  5. Site investigations, design, construction, operation, shutdown and surveillance of repositories for low- and intermediate-level radioactive wastes in rock cavities

    1984-01-01

    The report provides an overview and technical guidelines for considerations and for activities to be undertaken for safety assessment, site investigations, design, construction, operation, shutdown and surveillance of repositories for the disposal of low- and intermediate-level radioactive wastes in rock cavities. A generalized sequence of investigations is introduced which proceeds through region and site selection to the stage where the site is confirmed by detailed geoscientific investigations as being suitable for a waste repository. The different procedures and somewhat specific investigative needs with respect to existing mines are dealt with separately. General design, as well as specific requirements with respect to the different stages of design and construction, are dealt with. A review of activities related to the operational and post-operational stages of repositories in rock cavities is presented. The report describes in general terms the procedures related to different stages of disposal operation; also the conditions for shutdown together with essential shutdown and sealing activities and the related safety assessment requirements. Guidance is also given on the surveillance programme which will allow for inspection, testing, maintenance and security of a disposal facility during the operational phase, as well as for the post-operational stage for periods determined as necessary by the national authorities

  6. Additive Manufactured Superconducting Cavities

    Holland, Eric; Rosen, Yaniv; Woolleet, Nathan; Materise, Nicholas; Voisin, Thomas; Wang, Morris; Mireles, Jorge; Carosi, Gianpaolo; Dubois, Jonathan

    Superconducting radio frequency cavities provide an ultra-low dissipative environment, which has enabled fundamental investigations in quantum mechanics, materials properties, and the search for new particles in and beyond the standard model. However, resonator designs are constrained by limitations in conventional machining techniques. For example, current through a seam is a limiting factor in performance for many waveguide cavities. Development of highly reproducible methods for metallic parts through additive manufacturing, referred to colloquially as 3D printing\\x9D, opens the possibility for novel cavity designs which cannot be implemented through conventional methods. We present preliminary investigations of superconducting cavities made through a selective laser melting process, which compacts a granular powder via a high-power laser according to a digitally defined geometry. Initial work suggests that assuming a loss model and numerically optimizing a geometry to minimize dissipation results in modest improvements in device performance. Furthermore, a subset of titanium alloys, particularly, a titanium, aluminum, vanadium alloy (Ti - 6Al - 4V) exhibits properties indicative of a high kinetic inductance material. This work is supported by LDRD 16-SI-004.

  7. Pacer processing: cavity inventory relationships

    Dietz, R.J.; Gritzo, L.A.

    1975-09-01

    The pacer cavity and its associated primary power loop comprise a recirculating system in which materials are introduced by a series of thermonuclear explosions while debris is continuously removed by radioactive decay, sorption phenomena, and deliberate processing. Safe, reliable, and economical realization of the Pacer concept depends on the removal and control of both noxious and valuable by-products of the fusion reaction. Mathematical relationships are developed that describe the quantities of materials that are introduced into the Pacer cavity by a series of discrete events and are removed continuously by processing and decay. An iterative computer program based on these relationships is developed that allows both the total cavity inventory and the amounts of important individual species to be determined at any time during the lifetime of the cavity in order to establish the effects of the thermonuclear event, the cavity, the flow, and various processing parameters on Pacer design requirements

  8. Design Of A Novel Open-Path Aerosol Extinction Cavity Ringdown Spectrometer And Initial Data From Deployment At NOAA's Atmospheric Observatory

    Gordon, T. D.; Wagner, N. L.; Richardson, M.; Law, D. C.; Wolfe, D. E.; Brock, C. A.; Erdesz, F.; Murphy, D. M.

    2014-12-01

    The ability to frame effective climate change policy depends strongly on reducing the uncertainty in aerosol radiative forcing, which is currently nearly as great as best estimates of its magnitude. Achieving this goal will require significant progress in measuring aerosol properties, including aerosol optical depth, single scattering albedo and the effect of relative humidity on these properties for both fine and coarse particles. However both ground- and space-based instruments fail or are highly biased in the presence of clouds, severely limiting quantitative estimates of the radiative effects of aerosols where they are advected over low-level clouds. Moreover, many in situ aerosol measurements exclude the coarse fraction, which can be very important in and downwind of desert regions. By measuring the decay rate of a pulsed laser in an optically resonant cavity, cavity ringdown spectrometers (CRDSs) have been employed successfully in measuring aerosol extinction for particles in relative humidities below 90%. At very high humidities (as found in and near clouds), however, existing CRDSs perform poorly, diverging significantly from theoretical extinction values as humidities approach 100%. The new open-path aerosol extinction CRDS described in this poster measures extinction as aerosol is drawn through the sample cavity directly without inlets or tubing for channeling the flow, which cause particle losses, condensation at high RH and other artifacts. This poster presents the key elements of the new open-path CRDS design as well as comparisons with an earlier generation closed-path CRDS and preliminary data obtained during a field study at the 300 meter tower at NOAA's Boulder Atmospheric Observatory (BAO) in Colorado.

  9. A SiGe High Gain and Highly Linear F-Band Single-Balanced Subharmonic Mixer

    Seyedhosseinzadeh, Neda; Nabavi, Abdolreza; Carpenter, Sona; He, Zhongxia Simon; Bao, Mingquan; Zirath, Herbert

    2017-01-01

    A compact, broadband, high gain, second-order active down-converter subharmonic mixer is demonstrated using a 130-nm SiGe BiCMOS technology. The mixer adopts a bottom-LO Gilbert topology, on-chip RF and LO baluns and two emitter-follower buffers to realize a high gain wideband operation in both RF and IF frequencies. The measured performance exhibits a flat conversion gain (CG) of about 11 dB from 90 to 130 GHz with an average LO power of +3 dBm and high 2LO-RF isolation better than 60 dB. Th...

  10. Optofluidic Fabry-Pérot Micro-Cavities Comprising Curved Surfaces for Homogeneous Liquid Refractometry—Design, Simulation, and Experimental Performance Assessment

    Noha Gaber

    2016-04-01

    Full Text Available In the scope of miniaturized optical sensors for liquid refractometry, this work details the design, numerical simulation, and experimental characterization of a Fabry-Pérot resonator consisting of two deeply-etched silicon cylindrical mirrors with a micro-tube in between holding the liquid analyte under study. The curved surfaces of the tube and the cylindrical mirrors provide three-dimensional light confinement and enable achieving stability for the cavity illuminated by a Gaussian beam input. The resonant optofluidic cavity attains a high-quality factor (Q—over 2800—which is necessary for a sensitive refractometer, not only by providing a sharp interference spectrum peak that enables accurate tracing of the peak wavelengths shifts, but also by providing steep side peaks, which enables detection of refractive index changes by power level variations when operating at a fixed wavelength. The latter method can achieve refractometry without the need for spectroscopy tools, provided certain criteria explained in the details are met. By experimentally measuring mixtures of acetone-toluene with different ratios, refractive index variations of 0.0005 < Δn < 0.0022 could be detected, with sensitivity as high as 5500 μW/RIU.

  11. Investigation of superconducting niobium 1170 MHz cavities

    Anashin, V.V.; Bibko, S.I.; Fadeyev, E.I.

    1988-01-01

    The design, fabrication and experiments with superconducting L-band single cell cavities are described. These cavities model a cell of an accelerating RF structure. The cavities have been fabricated from technical grade and higher purity grade sheet niobium using deep-drawing, electron beam welding and chemical polishing. They have spherical geometry and are excited in the TM 010 mode. A computerized set-up was used for cavity tests. Qo=1.5 x 10 9 and E acc = 4.3 MV/m were obtained in the cavity made of higher purity grade niobium. 6 references, 8 figures, 3 tables

  12. LHC crab-cavity aspects and strategy

    Calaga, R.; Tomas, R.; Zimmermann, F.

    2010-01-01

    The 3rd LHC Crab Cavity workshop (LHC-CC09) took place at CERN in October 2009. It reviewed the current status and identified a clear strategy towards a future crab-cavity implementation. Following the success of crab cavities in KEK-B and the strong potential for luminosity gain and leveling, CERN will pursue crab crossing for the LHC upgrade. We present a summary and outcome of the variousworkshop sessions which have led to the LHC crab-cavity strategy, covering topics like layout, cavity design, integration, machine protection, and a potential validation test in the SPS.

  13. Physical optimization of a wavy porous cavity filled by nanofluids in the presence of solar radiations using the Box-Behnken design (BBD)

    Ghorbanian, A.; Tahari, M.; Hatami, M.

    2017-06-01

    In this paper, the physical optimization of a wavy porous cavity is evaluated while it is filled with nanofluids and under the solar radiation heat flux by using numerical and statistical methods. The effect of four parameters is discussed on the Nusselt number: Wavy amplitude ( Am, solar heat flux, Darcy number and Rayleigh number. To find the effect and interaction of these parameters on the heat transfer, a Box-Behnken design (BBD) is used and analysis is performed on the 27 experiments proposed by BBD. Analysis of variance (ANOVA) of the results revealed that solar heat flux and wave amplitude have a strong effect on the Nusselt number compared to Darcy and Rayleigh numbers. Finally, the response surface methodology (RSM) was applied to find the optimized case while its error was 0.002% in predicting the Nusselt number for the optimized case which confirms the high accuracy of results.

  14. Multistate intermittency on the route to chaos of a semiconductor laser subjected to optical feedback from a long external cavity.

    Choi, Daeyoung; Wishon, Michael J; Chang, C Y; Citrin, D S; Locquet, A

    2018-01-01

    We observe experimentally two regimes of intermittency on the route to chaos of a semiconductor laser subjected to optical feedback from a long external cavity as the feedback level is increased. The first regime encountered corresponds to multistate intermittency involving two or three states composed of several combinations of periodic, quasiperiodic, and subharmonic dynamics. The second regime is observed for larger feedback levels and involves intermittency between period-doubled and chaotic regimes. This latter type of intermittency displays statistical properties similar to those of on-off intermittency.

  15. Half-Watt average power femtosecond source spanning 3-8 µm based on subharmonic generation in GaAs

    Smolski, Viktor; Vasilyev, Sergey; Moskalev, Igor; Mirov, Mike; Ru, Qitian; Muraviev, Andrey; Schunemann, Peter; Mirov, Sergey; Gapontsev, Valentin; Vodopyanov, Konstantin

    2018-06-01

    Frequency combs with a wide instantaneous spectral span covering the 3-20 µm molecular fingerprint region are highly desirable for broadband and high-resolution frequency comb spectroscopy, trace molecular detection, and remote sensing. We demonstrate a novel approach for generating high-average-power middle-infrared (MIR) output suitable for producing frequency combs with an instantaneous spectral coverage close to 1.5 octaves. Our method is based on utilizing a highly-efficient and compact Kerr-lens mode-locked Cr2+:ZnS laser operating at 2.35-µm central wavelength with 6-W average power, 77-fs pulse duration, and high 0.9-GHz repetition rate; to pump a degenerate (subharmonic) optical parametric oscillator (OPO) based on a quasi-phase-matched GaAs crystal. Such subharmonic OPO is a nearly ideal frequency converter capable of extending the benefits of frequency combs based on well-established mode-locked pump lasers to the MIR region through rigorous, phase- and frequency-locked down conversion. We report a 0.5-W output in the form of an ultra-broadband spectrum spanning 3-8 µm measured at 50-dB level.

  16. TESLA superconducting RF cavity development

    Koepke, K.

    1995-01-01

    The TESLA collaboration has made steady progress since its first official meeting at Cornell in 1990. The infrastructure necessary to assemble and test superconducting rf cavities has been installed at the TESLA Test Facility (TTF) at DESY. 5-cell, 1.3 GHz cavities have been fabricated and have reached accelerating fields of 25 MV/m. Full sized 9-cell copper cavities of TESLA geometry have been measured to verify the higher order modes present and to evaluate HOM coupling designs. The design of the TESLA 9-cell cavity has been finalized and industry has started delivery. Two prototype 9-cell niobium cavities in their first tests have reached accelerating fields of 10 MV/m and 15 MV/m in a vertical dewar after high peak power (HPP) conditioning. The first 12 m TESLA cryomodule that will house 8 9-cell cavities is scheduled to be delivered in Spring 1995. A design report for the TTF is in progress. The TTF test linac is scheduled to be commissioned in 1996/1997. (orig.)

  17. Die-cavity Design for High-Precision Nett-Forming of Engineering Component (PRECI4M)

    Ravn, Bjarne Gottlieb

    This report covers the 6-months period from month 37 to month 42 of the project. The following tasks are reported: • Task 14: Auto-interface between Data Retrieval and FE Analysis Software • Task 21: Tool Design Principles • Task 23: Specification of Tool Design System • Task 54: Development of S...... of Software Codes • Task 61: Design of Experiments for Validation • Task 62: Validation Experiments......This report covers the 6-months period from month 37 to month 42 of the project. The following tasks are reported: • Task 14: Auto-interface between Data Retrieval and FE Analysis Software • Task 21: Tool Design Principles • Task 23: Specification of Tool Design System • Task 54: Development...

  18. STRUCTURAL ANALYSIS OF SUPERCONDUCTING ACCELERATOR CAVITIES

    Schrage, D.

    2000-01-01

    The static and dynamic structural behavior of superconducting cavities for various projects was determined by finite element structural analysis. The β = 0.61 cavity shape for the Neutron Science Project was studied in detail and found to meet all design requirements if fabricated from five millimeter thick material with a single annular stiffener. This 600 MHz cavity will have a Lorentz coefficient of minus1.8 Hz/(Mv/meter) 2 and a lowest structural resonance of more than 100 Hz. Cavities at β = 0.48, 0.61, and 0.77 were analyzed for a Neutron Science Project concept which would incorporate 7-cell cavities. The medium and high beta cavities were found to meet all criteria but it was not possible to generate a β = 0.48 cavity with a Lorentz coefficient of less than minus3 Hz/(Mv/meter) 2

  19. Cavity enhancement by controlled directional scattering

    Winston, R.

    1980-01-01

    A method for designing cavity enclosures is presented that can be applied to the design of a nonimaging concentrator. The method maintains high transmission at the expense of some concentration in the presence of a gap between the reflector and the receiver. The slight loss of concentration may be partly offset by enhanced absorption of radiation by the receiver, resulting from the cavity effect.

  20. Toroidal 12 cavity klystron : a novel approach

    Hazarika, A.B.R.

    2013-01-01

    A toroidal 12 cavity klystron is designed to provide with high energy power with the high frequency microwave RF- plasma generated from it. The cavities are positioned in clock hour positions. The theoretical modeling and designing is done to study the novel approach. (author)

  1. Segmented trapped vortex cavity

    Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)

    2010-01-01

    An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.

  2. Development of the L-band superconducting cavity system

    Ota, T.; Kakutani, N.; Sukenobu, S. [Toshiba Corp., Yokohama, Kanagawa (JP)] [and others

    2000-02-01

    R and D activities on superconducting cavities in 1998 at TOSHIBA are presented. An L-band single-cell niobium cavity with four ports on the beam pipes was fabricated in our company and tested at KEK. The cryostat and refrigerator system for the cavity were designed and fabricated. The cryostat installed the cavity was tested in low temperature. R and D of hydroforming to fabricate seamless cavities is also presented. (author)

  3. Development of the L-band superconducting cavity system

    Ota, T.; Kakutani, N.; Sukenobu, S.

    2000-01-01

    R and D activities on superconducting cavities in 1998 at TOSHIBA are presented. An L-band single-cell niobium cavity with four ports on the beam pipes was fabricated in our company and tested at KEK. The cryostat and refrigerator system for the cavity were designed and fabricated. The cryostat installed the cavity was tested in low temperature. R and D of hydroforming to fabricate seamless cavities is also presented. (author)

  4. JLab SRF Cavity Fabrication Errors, Consequences and Lessons Learned

    Marhauser, Frank

    2011-01-01

    Today, elliptical superconducting RF (SRF) cavities are preferably made from deep-drawn niobium sheets as pursued at Jefferson Laboratory (JLab). The fabrication of a cavity incorporates various cavity cell machining, trimming and electron beam welding (EBW) steps as well as surface chemistry that add to forming errors creating geometrical deviations of the cavity shape from its design. An analysis of in-house built cavities over the last years revealed significant errors in cavity production. Past fabrication flaws are described and lessons learned applied successfully to the most recent in-house series production of multi-cell cavities.

  5. Prestressed concrete reactor vessel for the HHT-670 MW(e) demonstration plant. Pt.1. Design of the multi-cavity prestressed concrete reactor vessel with warm liner

    Lafitte, R.; Marchand, J.D.

    1979-01-01

    The design studies and tests described in this paper were undertaken as part of ''PROJECT HHT'', a German-Swiss joint effort for the development of high-temperature helium cooled reactors with direct-cycle turbine. The prestressed concrete reactor pressure vessel encloses the core of the reactor itself, the heat exchangers (coolers and recuperators), the helium turbine, the main helium circuit, all nuclear and thermal equipment, and auxiliary reactor cooling equipment. In order to make the liner accessible for inspection, no thermal insulation is provided between the coolant and the liner. The temperature of the helium in contact with the liner is limited to 200 0 C, under all normal operation conditions of the reactor. In the HHT reactor pressure vessel, the resisting structure is protected thermally by a layer of warm concrete between the liner and the structural prestressed concrete. The main features of this pressure vessel are the marked pressure differences in the cavities during normal operation, and the use of warm liner. The objectives of the reference design were chiefly related to the sizing up of the main structure, taking into account the modifications to be expected in the material characteristics as a result of the high temperatures developed

  6. Beam Dynamics Studies and the Design, Fabrication and Testing of Superconducting Radiofrequency Cavity for High Intensity Proton Accelerator

    Saini, Arun [Univ. of Delhi, New Delhi (India)

    2012-03-01

    The application horizon of particle accelerators has been widening significantly in recent decades. Where large accelerators have traditionally been the tools of the trade for high-energy nuclear and particle physics, applications in the last decade have grown to include large-scale accelerators like synchrotron light sources and spallation neutron sources. Applications like generation of rare isotopes, transmutation of nuclear reactor waste, sub-critical nuclear power, generation of neutrino beams etc. are next area of investigation for accelerator scientific community all over the world. Such applications require high beam power in the range of few mega-watts (MW). One such high intensity proton beam facility is proposed at Fermilab, Batavia, US, named as Project-X. Project-X facility is based on H- linear accelerator (linac), which will operate in continuous wave (CW) mode and accelerate H- ion beam with average current of 1 mA from kinetic energy of 2.5 MeV to 3 GeV to deliver 3MW beam power. One of the most challenging tasks of the Project-X facility is to have a robust design of the CW linac which can provide high quality beam to several experiments simultaneously. Hence a careful design of linac is important to achieve this objective.

  7. A superconducting test cavity for DORIS

    Bauer, W.; Brandelik, A.; Lekmann, W.; Szecsi, L.

    1978-03-01

    A summary of experimental goals, technical requirements and possible solutions for the construction of a superconducting accelerating cavity to be tested at DORIS is given. The aim of the experiment is to prove the applicability of superconducting cavities in storage rings and to study the problems typical for this application. The paper collects design considerations about cavity geometry and fabrication, input coupling, output coupling for higher modes, tuner, cryostat and controls. (orig.) [de

  8. Optical microfiber-based photonic crystal cavity

    Yu, Yang; Sun, Yi-zhi; Li, Zhi-yuan; Ding, Wei; Andrews, Steve

    2016-01-01

    Using a focused ion beam milling technique, we fabricate broad stop band (∼10% wide) photonic crystal (PhC) cavities in adiabatically-tapered silica fibers. Abrupt structural design of PhC mirrors efficiently reduces radiation loss, increasing the cavity finesse to ∼7.5. Further experiments and simulations verify that the remaining loss is mainly due to Ga ion implantation. Such a microfiber PhC cavity probably has potentials in many light-matter interaction applications. (paper)

  9. A beamline design and data acquisition with the 20-MeV, 20-ps electron beam for the higher-order mode studies of the APS SR-rf cavities

    Song, J.; Nassiri, A.; Daly, R.

    1993-01-01

    A beamline has been designed and assembled to use the ANL Chemistry Division 20-MeV electron linac for the testing of higher-order mode excitation and damping in rf cavities. The beamline consists of two sections (a beam collimating section with a 1.5 inches-OD vacuum line, and a cavity test section with a 3 inches-OD vacuum line), separated by two double aluminum foil windows. The beam diagnostics consist of a stripline beam position monitor, integrating current transformers, fluorescent screens, and a Faraday cup. EPICS (Experimental Physics and Industrial Control System) is used for beamline control, monitoring, and data acquisition. Also described is the diagnostic system used for beam image capture and analysis using EPICS-controlled hardware and PV-WAVE software. The rf cavity measurement will be described in a separate paper

  10. Development of Side Coupled Cavities

    Conto, J.M. de; Carretta, J.M.; Gomez-Martinez, Y.; Micoud, R.

    2008-01-01

    Side coupled Cavities are good candidates for proton accelerations in the 90-180 MeV range, as it has been first proposed for the CERN LINAC4 project. A side coupled Linac is made of a lump chain of resonant cavities, alternatively accelerating and coupling. A side coupled cavity has been designed in a CERN-LPSC collaboration to achieve LINAC4 requirements. After RF studies, a complete thermal study has been done, showing that 10-15% is the absolute maximum duty-cycle achievable by such a cavity. Error studies have been developed. They have shown that a tuning ring is mandatory and that a K equals 3% coupling factor is a good choice. A prototype has been built and each cell has been measured and tuned. A simple and accurate method has been used to get both the resonant frequency and the coupling factor, with a movable tuner and a linear fit. A similar method has been used to get the second order coupling factor. A large dispersion is observed on K. This is mainly due to the shape of the coupling apertures, which are very sensitive to mechanical errors. A future and realistic design must be very careful to guarantee a constant aperture (the important parameter is more the dispersion of k than its exact value). Finally, we analyse how to tune the cavity. This has to checked carefully and probably improved or corrected. Results are expected for mid-2008

  11. Superconducting cavity driving with FPGA controller

    Czarski, Tomasz; Koprek, Waldemar; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Simrock, Stefan; Brandt, Alexander; Chase, Brian; Carcagno, Ruben; Cancelo, Gustavo; Koeth, Timothy W.

    2006-01-01

    A digital control of superconducting cavities for a linear accelerator is presented. FPGA-based controller, supported by Matlab system, was applied. Electrical model of a resonator was used for design of a control system. Calibration of the signal path is considered. Identification of cavity parameters has been carried out for adaptive control algorithm. Feed-forward and feedback modes were applied in operating the cavities. Required performance has been achieved; i.e. driving on resonance during filling and field stabilization during flattop time, while keeping reasonable level of the power consumption. Representative results of the experiments are presented for different levels of the cavity field gradient

  12. Mounting system for optical frequency reference cavities

    Notcutt, Mark (Inventor); Hall, John L. (Inventor); Ma, Long-Sheng (Inventor)

    2008-01-01

    A technique for reducing the vibration sensitivity of laser-stabilizing optical reference cavities is based upon an improved design and mounting method for the cavity, wherein the cavity is mounted vertically. It is suspended at one plane, around the spacer cylinder, equidistant from the mirror ends of the cavity. The suspension element is a collar of an extremely low thermal expansion coefficient material, which surrounds the spacer cylinder and contacts it uniformly. Once the collar has been properly located, it is cemented in place so that the spacer cylinder is uniformly supported and does not have to be squeezed at all. The collar also includes a number of cavities partially bored into its lower flat surface, around the axial bore. These cavities are support points, into which mounting base pins will be inserted. Hence the collar is supported at a minimum of three points.

  13. Fast thermometry for superconducting rf cavity testing

    Orris, Darryl; Bellantoni, Leo; Carcagno, Ruben H.; Edwards, Helen; Harms, Elvin Robert; Khabiboulline, Timergali N.; Kotelnikov, Sergey; Makulski, Andrzej; Nehring, Roger; Pischalnikov, Yuriy; Fermilab

    2007-01-01

    Fast readout of strategically placed low heat capacity thermometry can provide valuable information of Superconducting RF (SRF) cavity performance. Such a system has proven very effective for the development and testing of new cavity designs. Recently, several resistance temperature detectors (RTDs) were installed in key regions of interest on a new 9 cell 3.9 GHz SRF cavity with integrated HOM design at FNAL. A data acquisition system was developed to read out these sensors with enough time and temperature resolution to measure temperature changes on the cavity due to heat generated from multipacting or quenching within power pulses. The design and performance of the fast thermometry system will be discussed along with results from tests of the 9 cell 3.9GHz SRF cavity

  14. Fast thermometry for superconducting rf cavity testing

    Orris, Darryl; Bellantoni, Leo; Carcagno, Ruben H.; Edwards, Helen; Harms, Elvin Robert; Khabiboulline, Timergali N.; Kotelnikov, Sergey; Makulski, Andrzej; Nehring, Roger; Pischalnikov, Yuriy; /Fermilab

    2007-06-01

    Fast readout of strategically placed low heat capacity thermometry can provide valuable information of Superconducting RF (SRF) cavity performance. Such a system has proven very effective for the development and testing of new cavity designs. Recently, several resistance temperature detectors (RTDs) were installed in key regions of interest on a new 9 cell 3.9 GHz SRF cavity with integrated HOM design at FNAL. A data acquisition system was developed to read out these sensors with enough time and temperature resolution to measure temperature changes on the cavity due to heat generated from multipacting or quenching within power pulses. The design and performance of the fast thermometry system will be discussed along with results from tests of the 9 cell 3.9GHz SRF cavity.

  15. Improved reactor cavity

    Katz, L.R.; Demarchais, W.E.

    1984-01-01

    A reactor pressure vessel disposed in a cavity has coolant inlet or outlet pipes extending through passages in the cavity walls and welded to pressure nozzles. The cavity wall has means for directing fluid away from a break at a weld away from the pressure vessel, and means for inhibiting flow of fluid toward the vessel. (author)

  16. RF control studies for moderate beamtime coupling between SRF cavities

    Doolittle, L.R.; Wang, D.X.

    1998-01-01

    When an SRF accelerator is designed, there is motivation to move the cavities close together on the beamline. Assuming the beamline apertures are not shrunk as well, this compaction (which will increase the overall accelerating gradient and/or lower the dynamic cryogenic heat load) increases the inter-cavity coupling. Within certain limits, the control system can compensate for this coupling by retuning each of the cavities. This paper describes constraints on the RF system, tuners, couplers, and control systems that are required to provide stable operation of cavities in the presence of inter-cavity coupling that exceeds the loaded bandwidth of an individual cavity

  17. Hydrodynamic Drag on Streamlined Projectiles and Cavities

    Jetly, Aditya

    2016-04-19

    The air cavity formation resulting from the water-entry of solid objects has been the subject of extensive research due to its application in various fields such as biology, marine vehicles, sports and oil and gas industries. Recently we demonstrated that at certain conditions following the closing of the air cavity formed by the initial impact of a superhydrophobic sphere on a free water surface a stable streamlined shape air cavity can remain attached to the sphere. The formation of superhydrophobic sphere and attached air cavity reaches a steady state during the free fall. In this thesis we further explore this novel phenomenon to quantify the drag on streamlined shape cavities. The drag on the sphere-cavity formation is then compared with the drag on solid projectile which were designed to have self-similar shape to that of the cavity. The solid projectiles of adjustable weight were produced using 3D printing technique. In a set of experiments on the free fall of projectile we determined the variation of projectiles drag coefficient as a function of the projectiles length to diameter ratio and the projectiles specific weight, covering a range of intermediate Reynolds number, Re ~ 104 – 105 which are characteristic for our streamlined cavity experiments. Parallel free fall experiment with sphere attached streamlined air cavity and projectile of the same shape and effective weight clearly demonstrated the drag reduction effect due to the stress-free boundary condition at cavity liquid interface. The streamlined cavity experiments can be used as the upper bound estimate of the drag reduction by air layers naturally sustained on superhydrophobic surfaces in contact with water. In the final part of the thesis we design an experiment to test the drag reduction capacity of robust superhydrophobic coatings deposited on the surface of various model vessels.

  18. Electrically Pumped Vertical-Cavity Amplifiers

    Greibe, Tine

    2007-01-01

    In this work, the design of electrically pumped vertical cavity semiconductor optical amplifiers (eVCAs) for use in a mode-locked external-cavity laser has been developed, investigated and analysed. Four different eVCAs, one top-emitting and three bottom emitting structures, have been designed...... and discussed. The thesis concludes with recommendations for further work towards the realisation of compact electrically pumped mode-locked vertical externalcavity surface emitting lasers....

  19. The LHC superconducting cavities

    Boussard, Daniel; Häbel, E; Kindermann, H P; Losito, R; Marque, S; Rödel, V; Stirbet, M

    1999-01-01

    The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported.

  20. New achievements in RF cavity manufacturing

    Lippmann, G.; Pimiskern, K.; Kaiser, H.

    1993-01-01

    Dornier has been engaged in development, manufacturing and testing of Cu-, Cu/Nb- and Nb-cavities for many years. Recently, several different types of RF cavities were manufactured. A prototype superconducting (s.c.) B-Factory accelerating cavity (1-cell, 500 MHz) was delivered to Cornell University, Laboratory of Nuclear Studies. A second lot of 6 s.c. cavities (20-cell, 3000 MHz) was fabricated on contract from Technical University of Darmstadt for the S-DALINAC facility. Finally, the first copper RF structures (9-cell, 1300 MHz) for TESLA were finished and delivered to DESY, two s.c. niobium structures of the same design are in production. Highlights from the manufacturing processes of these cavities are described and first performance results will be reported

  1. Fiber cavities with integrated mode matching optics.

    Gulati, Gurpreet Kaur; Takahashi, Hiroki; Podoliak, Nina; Horak, Peter; Keller, Matthias

    2017-07-17

    In fiber based Fabry-Pérot Cavities (FFPCs), limited spatial mode matching between the cavity mode and input/output modes has been the main hindrance for many applications. We have demonstrated a versatile mode matching method for FFPCs. Our novel design employs an assembly of a graded-index and large core multimode fiber directly spliced to a single mode fiber. This all-fiber assembly transforms the propagating mode of the single mode fiber to match with the mode of a FFPC. As a result, we have measured a mode matching of 90% for a cavity length of ~400 μm. This is a significant improvement compared to conventional FFPCs coupled with just a single mode fiber, especially at long cavity lengths. Adjusting the parameters of the assembly, the fundamental cavity mode can be matched with the mode of almost any single mode fiber, making this approach highly versatile and integrable.

  2. Voltage control of cavity magnon polariton

    Kaur, S., E-mail: kaurs3@myumanitoba.ca; Rao, J. W.; Gui, Y. S.; Hu, C.-M., E-mail: hu@physics.umanitoba.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Yao, B. M. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai 200083 (China)

    2016-07-18

    We have experimentally investigated the microwave transmission of the cavity-magnon-polariton (CMP) generated by integrating a low damping magnetic insulator onto a 2D microwave cavity. The high tunability of our planar cavity allows the cavity resonance frequency to be precisely controlled using a DC voltage. By appropriately tuning the voltage and magnetic bias, we can observe the cavity photon magnon coupling and the magnetic coupling between a magnetostatic mode and the generated CMP. The dispersion of the generated CMP was measured by either tuning the magnetic field or the applied voltage. This electrical control of CMP may open up avenues for designing advanced on-chip microwave devices that utilize light-matter interaction.

  3. LEP copper accelerating cavities

    Laurent Guiraud

    1999-01-01

    These copper cavities were used to generate the radio frequency electric field that was used to accelerate electrons and positrons around the 27-km Large Electron-Positron (LEP) collider at CERN, which ran from 1989 to 2000. The copper cavities were gradually replaced from 1996 with new superconducting cavities allowing the collision energy to rise from 90 GeV to 200 GeV by mid-1999.

  4. Superconducting versus normal conducting cavities

    Podlech, Holger

    2013-01-01

    One of the most important issues of high-power hadron linacs is the choice of technology with respect to superconducting or room-temperature operation. The favour for a specific technology depends on several parameters such as the beam energy, beam current, beam power and duty factor. This contribution gives an overview of the comparison between superconducting and normal conducting cavities. This includes basic radiofrequency (RF) parameters, design criteria, limitations, required RF and plug power as well as case studies.

  5. Accoustic Localization of Breakdown in Radio Frequency Accelerating Cavities

    Lane, Peter Gwin [IIT, Chicago

    2016-07-01

    Current designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. In this context and in general, the use of RF cavities in strong magnetic fields has its challenges. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to small regions of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Details on RF cavity sound sources as well as the hardware, software, and algorithms used to localize the source of sound emitted from breakdown thermal shocks are presented. In addition, results from simulations and experiments on three RF cavities, namely the Aluminum Mock Cavity, the High-Pressure Cavity, and the Modular Cavity, are also given. These results demonstrate the validity and effectiveness of the described technique for acoustic localization of breakdown.

  6. Cavity quantum electrodynamics

    Walther, Herbert; Varcoe, Benjamin T H; Englert, Berthold-Georg; Becker, Thomas

    2006-01-01

    This paper reviews the work on cavity quantum electrodynamics of free atoms. In recent years, cavity experiments have also been conducted on a variety of solid-state systems resulting in many interesting applications, of which microlasers, photon bandgap structures and quantum dot structures in cavities are outstanding examples. Although these phenomena and systems are very interesting, discussion is limited here to free atoms and mostly single atoms because these systems exhibit clean quantum phenomena and are not disturbed by a variety of other effects. At the centre of our review is the work on the one-atom maser, but we also give a survey of the entire field, using free atoms in order to show the large variety of problems dealt with. The cavity interaction can be separated into two main regimes: the weak coupling in cavity or cavity-like structures with low quality factors Q and the strong coupling when high-Q cavities are involved. The weak coupling leads to modification of spontaneous transitions and level shifts, whereas the strong coupling enables one to observe a periodic exchange of photons between atoms and the radiation field. In this case, atoms and photons are entangled, this being the basis for a variety of phenomena observed, some of them leading to interesting applications in quantum information processing. The cavity experiments with free atoms reached a new domain with the advent of experiments in the visible spectral region. A review on recent achievements in this area is also given

  7. Fundamental limitations of cavity-assisted atom interferometry

    Dovale-Álvarez, M.; Brown, D. D.; Jones, A. W.; Mow-Lowry, C. M.; Miao, H.; Freise, A.

    2017-11-01

    Atom interferometers employing optical cavities to enhance the beam splitter pulses promise significant advances in science and technology, notably for future gravitational wave detectors. Long cavities, on the scale of hundreds of meters, have been proposed in experiments aiming to observe gravitational waves with frequencies below 1 Hz, where laser interferometers, such as LIGO, have poor sensitivity. Alternatively, short cavities have also been proposed for enhancing the sensitivity of more portable atom interferometers. We explore the fundamental limitations of two-mirror cavities for atomic beam splitting, and establish upper bounds on the temperature of the atomic ensemble as a function of cavity length and three design parameters: the cavity g factor, the bandwidth, and the optical suppression factor of the first and second order spatial modes. A lower bound to the cavity bandwidth is found which avoids elongation of the interaction time and maximizes power enhancement. An upper limit to cavity length is found for symmetric two-mirror cavities, restricting the practicality of long baseline detectors. For shorter cavities, an upper limit on the beam size was derived from the geometrical stability of the cavity. These findings aim to aid the design of current and future cavity-assisted atom interferometers.

  8. Superconducting spoke cavities for high-velocity applications

    Hopper, Christopher S. [Old Dominion U.; Delayen, Jean R. [Old Dominion U., JLAB

    2013-10-01

    To date, superconducting spoke cavities have been designed, developed, and tested for particle velocities up to {beta}{sub 0}~0.6, but there is a growing interest in possible applications of multispoke cavities for high-velocity applications. We have explored the design parameter space for low-frequency, high-velocity, double-spoke superconducting cavities in order to determine how each design parameter affects the electromagnetic properties, in particular the surface electromagnetic fields and the shunt impedance. We present detailed design for cavities operating at 325 and 352 MHz and optimized for {beta}{sub 0}~=0.82 and 1.

  9. Formation of coronal cavities

    An, C.H.; Suess, S.T.; Tandberg-Hanssen, E.; Steinolfson, R.S.

    1986-01-01

    A theoretical study of the formation of a coronal cavity and its relation to a quiescent prominence is presented. It is argued that the formation of a cavity is initiated by the condensation of plasma which is trapped by the coronal magnetic field in a closed streamer and which then flows down to the chromosphere along the field lines due to lack of stable magnetic support against gravity. The existence of a coronal cavity depends on the coronal magnetic field strength; with low strength, the plasma density is not high enough for condensation to occur. Furthermore, we suggest that prominence and cavity material is supplied from the chromospheric level. Whether a coronal cavity and a prominence coexist depends on the magnetic field configuration; a prominence requires stable magnetic support

  10. RF cavity evaluation with the code SUPERFISH

    Hori, T.; Nakanishi, T.; Ueda, N.

    1982-01-01

    The computer code SUPERFISH calculates axisymmetric rf fields and is most applicable to re-entrant cavities of an Alvarez linac. Some sample results are shown for the first Alvarez's in NUMATRON project. On the other hand the code can also be effectivily applied to TE modes excited in an RFQ linac when the cavity is approximately considered as positioning at an infinite distance from the symmetry axis. The evaluation was made for several RFQ cavities, models I, II and a test linac named LITL, and useful results for the resonator design were obtained. (author)

  11. Micro-Cavity Fluidic Dye Laser

    Helbo, Bjarne; Kristensen, Anders; Menon, Aric Kumaran

    2003-01-01

    We have successfully designed, fabricated and characterized a micro-cavity fluidic dye laser with metallic mirrors, which can be integrated with polymer based lab-on-a-chip microsystems without further processing steps. A simple rate-equation model is used to predict the average pumping power...... threshold for lasing as function of cavity-mirror reflectance, laser dye concentration and cavity length. The laser device is characterized using the laser dye Rhodamine 6G dissolved in ethanol. Lasing is observed, and the influence of dye concentration is investigated....

  12. HOM power in FCC-ee cavities

    Karpov, Ivan; Chapochnikova, Elena

    2018-01-01

    This Note summarizes the results of the power loss calculations for FCC-ee machines with 400.79 MHz cavity options. The requirements for the single-cell cavity design and for the operation with beam are obtained from the results for the high-current FCC-ee machine (Z). For other machines the power loss is sufficiently low and can be absorbed and extracted by foreseen HOM couplers.

  13. High Accelerating Field Superconducting Radio Frequency Cavities

    Orr, R. S.; Saito, K.; Furuta, F.; Saeki, T.; Inoue, H.; Morozumi, Y.; Higo, T.; Higashi, Y.; Matsumoto, H.; Kazakov, S.; Yamaoka, H.; Ueno, K.; Sato, M.

    2008-06-01

    We have conducted a study of a series of single cell superconducting RF cavities at KEK. These tests were designed to investigate the effect of surface treatment on the maximum accelerating field attainable. All of these cavities are of the ICHIRO shape, based on the Low Loss shape. Our results indicate that accelerating fields as high as the theoretical maximum of 50MV/m are attainable.

  14. SPS RF Accelerating Cavity

    1979-01-01

    This picture shows one of the 2 new cavities installed in 1978-1979. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X

  15. The Finite Elements Method (FEM versus traditional Methods (TM, in the estimation of settlement and modulus of soil reaction for foundation slabs design on soils with natural or man-made cavities

    Escolano-Sánchez, F.

    2015-03-01

    Full Text Available Direct foundations with continuous elements, such as slabs, provide more advantages than direct foundations with isolated elements, such as footings, and deep foundations, such as piles, in the case of soil with natural or man-made cavities. The slabs are usually designed by two-dimensional models which show their shape on the plant, on a lineal elastic support, represented by a modulus of soil reaction. Regarding the settlement estimation, the following article compares the Finite Elements Method (FEM versus the classical Method (CM to select the modulus of soil reaction used to design foundations slabs in sensitive soils and sites with possible cavities or collapses. This analysis includes one of these cavities in the design to evaluate the risk of fail.Las cimentaciones directas con elementos continuos «losas», tienen ventajas sobre las cimentaciones directas con elementos aislados «zapatas» y sobre las cimentaciones profundas «pilotes», frente a la presencia de terrenos problemáticos. Las losas se diseñan de forma habitual con modelos bidimensionales que representan su forma en planta, apoyada en un medio elástico y lineal, representado por un módulo de balasto. En el presente artículo se realiza un análisis comparativo, para la estimación de asientos, entre el Método de Elementos Finitos (FEM y el Método Clásico (MC, para la elección de los módulos de balasto que se utilizan en el diseño de losas de cimentación en terrenos con blandones y cavidades naturales o antrópicas. Este análisis considera el peligro de la presencia de una de estas cavidades dentro de su diseño, de esta forma, el riesgo de fallo puede ser valorado por ambos métodos.

  16. Cavity-enhanced spectroscopies

    van Zee, Roger

    2003-01-01

    ""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr

  17. Tuned optical cavity magnetometer

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  18. Hydroforming of elliptical cavities

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, P.

    2015-02-01

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV /m after buffered chemical polishing (BCP) and up to 42 MV /m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30 - 35 MV /m were measured after BCP and Eacc up to 40 MV /m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc=30 - 35 MV /m . One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have been

  19. Hydroforming of elliptical cavities

    W. Singer

    2015-02-01

    Full Text Available Activities of the past several years in developing the technique of forming seamless (weldless cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients E_{acc} up to 35  MV/m after buffered chemical polishing (BCP and up to 42  MV/m after electropolishing (EP. More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients E_{acc} of 30–35  MV/m were measured after BCP and E_{acc} up to 40  MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of E_{acc}=30–35  MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and

  20. The CEBAF separator cavity resonance control system

    M. Wissmann; C. Hovater; A. Guerra; T. Plawski

    2005-01-01

    The CEBAF energy upgrade will increase the maximum beam energy from 6 GeV to 12 GeV available to the experimental halls. RF deflection cavities (separators) are used to direct the electron beam to the three halls. The resulting increase in RF separator cavity gradient and subsequent increase in RF power needed for these higher energies will require the cavities to have active resonance control. Currently, at the present 4 to 6 GeV energies, the cavities are tuned mechanically and then stabilized with Low Conductivity Water (LCW) which is maintained at a constant temperature of 95 Fahrenheit. This approach is no longer feasible and an active resonance control system that controls both water temperature and flow has been designed and built. The system uses a commercial PLC with embedded PID controls to regulate water temperature and flow to the cavities. The system allows the operator to remotely adjust temperature/flow and consequently cavity resonance for the full range of beam energies. Ultimately, closed loop control will be maintained by monitoring each cavity's reflected power. This paper describes this system

  1. Present status of superconducting cavity developments

    Ouchi, Nobuo; Kusano, Joichi; Hasegawa, Kazuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1997-11-01

    An R and D work of a superconducting (SC) cavity for the high intensity proton linac has begun at JAERI in collaboration with KEK. The RF field calculation and the structural analysis have been made to determine the cavity shape in the proton energy range between 100 and 1500 MeV. The results indicate the feasibility of a SC proton linac. A vertical test stand with clean room, water rinsing system, cavity evacuation pumping system, cryostat and data acquisition system has been installed to demonstrate the cavity performance. A single cell cavity of {beta}=0.5 has been fabricated and tested at the test stand to obtain the Q-value and the maximum surface electric field strength. The measured Q-values have been found to be high enough for our requirement while the field strength was limited to about 75% of the specification by the multipacting. We describe the preliminary design of the SC cavity, the overview of the vertical test stand and experimental results of the single cell cavity. (author)

  2. Cavity characterization for general use in linear electron accelerators

    Souza Neto, M.V. de.

    1985-01-01

    The main objective of this work is to is to develop measurement techniques for the characterization of microwave cavities used in linear electron accelerators. Methods are developed for the measurement of parameters that are essential to the design of an accelerator structure using conventional techniques of resonant cavities at low power. Disk-loaded cavities were designed and built, similar to those in most existing linear electron accelerators. As a result, the methods developed and the estimated accuracy were compared with those from other investigators. The results of this work are relevant for the design of cavities with the objective of developing linear electron accelerators. (author) [pt

  3. HOM frequency control of SRF cavity in high current ERLs

    Xu, Chen; Ben-Zvi, Ilan

    2018-03-01

    The acceleration of high-current beam in Superconducting Radio Frequency (SRF) cavities is a challenging but essential for a variety of advanced accelerators. SRF cavities should be carefully designed to minimize the High Order Modes (HOM) power generated in the cavities by the beam current. The reduction of HOM power we demonstrate in a particular case can be quite large. This paper presents a method to systematically control the HOM resonance frequencies in the initial design phase to minimize the HOM power generation. This method is expected to be beneficial for the design of high SRF cavities addressing a variety of Energy Recovery Linac (ERL) applications.

  4. Prototype 350 MHz niobium spoke-loaded cavities

    Delayen, J. R.; Kedzie, M.; Mammosser, J.; Piller, C.; Shepard, K. W.

    1999-01-01

    This paper reports the development of 350 MHz superconducting cavities of a spoke-loaded geometry, intended for the velocity range 0.2 < v/c < 0.6. Two prototype single-cell cavities have been designed, one optimized for velocity v/c = 0.4, and the other for v/c = 0.29. Construction of the prototype niobium cavities is nearly complete. Details of the design and construction are discussed, along with the results of cold tests

  5. Prototype 350 MHz niobium spoke-loaded cavities.

    Delayen, J. R.; Kedzie, M.; Mammosser, J.; Piller, C.; Shepard, K. W.

    1999-05-10

    This paper reports the development of 350 MHz superconducting cavities of a spoke-loaded geometry, intended for the velocity range 0.2 < v/c < 0.6. Two prototype single-cell cavities have been designed, one optimized for velocity v/c = 0.4, and the other for v/c = 0.29. Construction of the prototype niobium cavities is nearly complete. Details of the design and construction are discussed, along with the results of cold tests.

  6. SPS accelerating cavity

    CERN PhotoLab

    1976-01-01

    The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.

  7. Dental Sealants Prevent Cavities

    ... Digital Press Kit Read the MMWR Science Clips Dental Sealants Prevent Cavities Effective protection for children Language: ... more use of sealants and reimbursement of services. Dental care providers can Apply sealants to children at ...

  8. Statistical electromagnetics: Complex cavities

    Naus, H.W.L.

    2008-01-01

    A selection of the literature on the statistical description of electromagnetic fields and complex cavities is concisely reviewed. Some essential concepts, for example, the application of the central limit theorem and the maximum entropy principle, are scrutinized. Implicit assumptions, biased

  9. accelerating cavity from LEP

    This is an accelerating cavity from LEP, with a layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities are now used in LEP to double the energy of the particle beams.

  10. Hybrid vertical cavity laser

    Chung, Il-Sug; Mørk, Jesper

    2010-01-01

    A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide.......A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide....

  11. Efficient Characterization of Protein Cavities within Molecular Simulation Trajectories: trj_cavity.

    Paramo, Teresa; East, Alexandra; Garzón, Diana; Ulmschneider, Martin B; Bond, Peter J

    2014-05-13

    Protein cavities and tunnels are critical in determining phenomena such as ligand binding, molecular transport, and enzyme catalysis. Molecular dynamics (MD) simulations enable the exploration of the flexibility and conformational plasticity of protein cavities, extending the information available from static experimental structures relevant to, for example, drug design. Here, we present a new tool (trj_cavity) implemented within the GROMACS ( www.gromacs.org ) framework for the rapid identification and characterization of cavities detected within MD trajectories. trj_cavity is optimized for usability and computational efficiency and is applicable to the time-dependent analysis of any cavity topology, and optional specialized descriptors can be used to characterize, for example, protein channels. Its novel grid-based algorithm performs an efficient neighbor search whose calculation time is linear with system size, and a comparison of performance with other widely used cavity analysis programs reveals an orders-of-magnitude improvement in the computational cost. To demonstrate its potential for revealing novel mechanistic insights, trj_cavity has been used to analyze long-time scale simulation trajectories for three diverse protein cavity systems. This has helped to reveal, respectively, the lipid binding mechanism in the deep hydrophobic cavity of a soluble mite-allergen protein, Der p 2; a means for shuttling carbohydrates between the surface-exposed substrate-binding and catalytic pockets of a multidomain, membrane-proximal pullulanase, PulA; and the structural basis for selectivity in the transmembrane pore of a voltage-gated sodium channel (NavMs), embedded within a lipid bilayer environment. trj_cavity is available for download under an open-source license ( http://sourceforge.net/projects/trjcavity ). A simplified, GROMACS-independent version may also be compiled.

  12. Circuit QED with 3D cavities

    Xie, Edwar; Baust, Alexander; Zhong, Ling; Gross, Rudolf [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, TU Muenchen, Garching (Germany); Nanosystems Initiative Munich (NIM), Muenchen (Germany); Anderson, Gustav; Wang, Lujun; Eder, Peter; Fischer, Michael; Goetz, Jan; Haeberlein, Max; Schwarz, Manuel; Wulschner, Karl Friedrich; Deppe, Frank; Fedorov, Kirill; Huebl, Hans; Menzel, Edwin [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, TU Muenchen, Garching (Germany); Marx, Achim [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany)

    2015-07-01

    In typical circuit QED systems on-chip superconducting qubits are coupled to integrated coplanar microwave resonators. Due to the planar geometry, the resonators are often a limiting factor regarding the total coherence of the system. Alternatively, similar hybrid systems can be realized using 3D microwave cavities. Here, we present design considerations for the 3D microwave cavity as well as the superconducting transmon qubit. Moreover, we show experimental data of a high purity aluminum cavity demonstrating quality factors above 1.4 .10{sup 6} at the single photon level and a temperature of 50 mK. Our experiments also demonstrate that the quality factor is less dependent on the power compared to planar resonator geometries. Furthermore, we present strategies for tuning both the cavity and the qubit individually.

  13. Superconducting niobium cavities with high gradients

    Kneisel, P.; Saito, K.

    1992-01-01

    Present accelerator projects making use of superconducting cavity technology are constructed with design accelerating gradients E acc ranging between 5 MV/m and 8 MV/m and Q-values of several 10 9 . Future plans for upgrades of existing accelerators or for linear colliders call for gradients greater than 15 MV/m corresponding to peak surface electric fields above 30 MV/m. These demands challenge state-of-the-art production technology and require improvements in processing and handling of these cavities to overcome the major performance limitation of field emission loading. This paper reports on efforts to improve the performance of cavities made from niobium from different suppliers by using improved cleaning techniques after processing and ultrahigh vacuum annealing at temperatures of 1400 C. In single cell L-band cavities peak surface electric fields as high as 50 MV/m have been measured without significant field emission loading. (Author) 8 refs., fig

  14. Elliptical superconducting RF cavities for FRIB energy upgrade

    Ostroumov, P. N.; Contreras, C.; Plastun, A. S.; Rathke, J.; Schultheiss, T.; Taylor, A.; Wei, J.; Xu, M.; Xu, T.; Zhao, Q.; Gonin, I. V.; Khabiboulline, T.; Pischalnikov, Y.; Yakovlev, V. P.

    2018-04-01

    The multi-physics design of a five cell, βG = 0 . 61, 644 MHz superconducting elliptical cavity being developed for an energy upgrade in the Facility for Rare Isotope Beams (FRIB) is presented. The FRIB energy upgrade from 200 MeV/u to 400 MeV/u for heaviest uranium ions will increase the intensities of rare isotope beams by nearly an order of magnitude. After studying three different frequencies, 1288 MHz, 805 MHz, and 644 MHz, the 644 MHz cavity was shown to provide the highest energy gain per cavity for both uranium and protons. The FRIB upgrade will include 11 cryomodules containing 5 cavities each and installed in 80-meter available space in the tunnel. The cavity development included extensive multi-physics optimization, mechanical and engineering analysis. The development of a niobium cavity is complete and two cavities are being fabricated in industry. The detailed design of the cavity sub-systems such as fundamental power coupler and dynamic tuner are currently being pursued. In the overall design of the cavity and its sub-systems we extensively applied experience gained during the development of 650 MHz low-beta cavities at Fermi National Accelerator Laboratory (FNAL) for the Proton Improvement Plan (PIP) II.

  15. Deflecting cavity for beam diagnostics at Cornell ERL injector

    Belomestnykh, Sergey; Bazarov, Ivan; Shemelin, Valery; Sikora, John; Smolenski, Karl; Veshcherevich, Vadim

    2010-01-01

    A single-cell, 1300-MHz, TM110-like mode vertically deflecting cavity is designed and built for beam slice emittance measurements, and to study the temporal response of negative electron affinity photocathodes in the ERL injector at Cornell University. We describe the cavity shape optimization procedure, RF and mechanical design, its performance with beam.

  16. Design considerations of a MW-scale, high-efficiency, industrial-use, ultraviolet FEL amplifier

    Pagani, C.; Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.

    2000-01-01

    Theoretical and experimental work in free electron laser (FEL) physics, and the physics of particle accelerators over the last 10 years has pointed to the possibility of the generation of MW-level optical beams with laser-like characteristics in the ultraviolet (UV) spectral range. The concept is based on generation of the radiation in the master oscillator-power FEL amplifier (MOPA) configuration. The FEL amplifier concept eliminates the need for an optical cavity. As a result, there are no thermal loading limitations to increase the average output power of this device up to the MW-level. The problem of a tunable master oscillator can be solved with available conventional quantum lasers. The use of a superconducting energy-recovery linac could produce a major, cost-effective facility with wall plug power to output optical power efficiency of about 20% that spans wavelengths from the visible to the deep ultraviolet regime. The stringent electron beam qualities required for UV FEL amplifier operation can be met with a conservative injector design (using a conventional thermionic gun and subharmonic bunchers) and the beam compression and linear acceleration technology, recently developed in connection with high-energy linear collider and X-ray FEL programs

  17. Effects of Electric and Magnetic Fields on the Performance of a Superconducting Cavity

    Gianluigi Ciovati; Peter Kneisel; Jacek Sekutowicz; Waldemar Singer

    2005-01-01

    A special two-cell cavity was designed to obtain surface field distributions suitable for investigation of electric and magnetic field effects on cavity performance. The cavity design and preliminary results were presented in a previous contribution. The bulk niobium cavity was heat-treated in a vacuum furnace at 1250 C to improve thermal conductivity. Three seamless hydroformed Nb/Cu cavities of the same design were fabricated to investigate the role of the electron beam welds located in high field areas. This paper will present RF test results at 2 K for the bulk niobium and one of the seamless cavities

  18. Cavity QED with single trapped Ca+-ions

    Mundt, A.B.

    2003-02-01

    This thesis reports on the design and setup of a vacuum apparatus allowing the investigation of cavity QED effects with single trapped 40 Ca + ions. The weak coupling of ion and cavity in the 'bad cavity limit' may serve to inter--convert stationary and flying qubits. The ion is confined in a miniaturized Paul trap and cooled via the Doppler effect to the Lamb--Dicke regime. The extent of the atomic wave function is less than 30 nm. The ion is enclosed by a high finesse optical cavity. The technically--involved apparatus allows movement of the trap relative to the cavity and the trapped ion can be placed at any position in the standing wave. By means of a transfer lock the cavity can be resonantly stabilized with the S 1/2 ↔ D 5/2 quadrupole transition at 729 nm (suitable as a qubit) without light at that wavelength being present in the cavity. The coupling of the cavity field to the S 1/2 ↔ D 5/2 quadrupole transition is investigated with various techniques in order to determine the spatial dependence as well as the temporal dynamics. The orthogonal coupling of carrier and first--order sideband transitions at field nodes and antinodes is explored. The coherent interaction of the ion and the cavity field is confirmed by exciting Rabi oscillations with short resonant pulses injected into the cavity. Finally, first experimental steps towards the observation of cavity enhanced spontaneous emission have been taken. (author)

  19. Cavity Optomechanics at Millikelvin Temperatures

    Meenehan, Sean Michael

    mechanical frequency of these systems allows for the possibility of using a dilution refrigerator to simultaneously achieve low thermal occupancy and long mechanical coherence time by passively cooling the device to the millikelvin regime. This thesis describes efforts to realize the measurement of OMC cavities inside a dilution refrigerator, including the development of fridge-compatible optical coupling schemes and the characterization of the heating dynamics of the mechanical resonator at sub-kelvin temperatures. We will begin by summarizing the theoretical framework used to describe cavity optomechanical systems, as well as a handful of the quantum applications envisioned for such devices. Then, we will present background on the design of the nanobeam OMC cavities used for this work, along with details of the design and characterization of tapered fiber couplers for optical coupling inside the fridge. Finally, we will present measurements of the devices at fridge base temperatures of Tf = 10 mK, using both heterodyne spectroscopy and time-resolved sideband photon counting, as well as detailed analysis of the prospects for future quantum applications based on the observed optically-induced heating.

  20. Video Toroid Cavity Imager

    Gerald, Rex E. II; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  1. Metasurface external cavity laser

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  2. Test of superconducting radio-frequency cavity bombarded by protons

    O'Donnell, J. M.; McCloud, B. J.; Morris, C. L.; McClelland, J. B.; Rusnak, B.; Thiessen, H. A.; Langenbrunner, J. L.

    1992-05-01

    A beam of 2 × 10 10 protons/s was focused onto a small area on the high-field iris of a superconducting cavity operating at the resonance frequency. The input, reflected, and stored power were monitored. The cavity remained in steady state during this test. We conclude that such superconducting cavities will remain viable in the high-proton-flux environments proposed in the design of a superconducting accelerator for pions (PILAC).

  3. Test of superconducting radio-frequency cavity bombarded by protons

    O' Donnell, J.M.; McCloud, B.J.; Morris, C.L.; McClelland, J.B.; Rusnak, B.; Thiessen, H.A. (Los Alamos National Lab., NM (United States)); Langenbrunner, J.L. (Dept. of Physics and Astronomy, Univ. Minnesota, Minneapolis, MN (United States))

    1992-05-10

    A beam of 2x10{sup 10} protons/s was focused onto a small area on the high-field iris of a superconducting cavity operating at the resonance frequency. The input, reflected, and stored power were monitored. The cavity remained in steady state during this test. We conclude that such superconducting cavities will remain viable in the high-proton-flux environments proposed in the design of a superconducting accelerator for pions (PILAC). (orig.).

  4. Basic principles of RF superconductivity and superconducting cavities

    Schmüser, P

    2006-01-01

    The basics of superconductivity are outlined with special emphasis on the features which are relevant for the application of superconductors in radio frequency cavities for particle acceleration. For a cylindrical resonator (“pill box cavity”) the electromagnetic field in the cavity and important parameters such as resonance frequency, quality factor and shunt impedance are calculated analytically. The design and performance of practical cavities is shortly addressed.

  5. Earth-ionosphere cavity

    Tran, A.; Polk, C.

    1976-01-01

    To analyze ELF wave propagation in the earth-ionosphere cavity, a flat earth approximation may be derived from the exact equations, which are applicable to the spherical cavity, by introducing a second-order or Debye approximation for the spherical Hankel functions. In the frequency range 3 to 30 Hz, however, the assumed conditions for the Debye approximation are not satisfied. For this reason an exact evaluation of the spherical Hankel functions is used to study the effects of the flat earth approximation on various propagation and resonance parameters. By comparing the resonance equation for a spherical cavity with its flat earth counterpart and by assuming that the surface impedance Z/sub i/ at the upper cavity boundary is known, the relation between the eigenvalue ν and S/sub v/, the sine of the complex angle of incidence at the lower ionosphere boundary, is established as ν(ν + 1) = (kaS/sub v/) 2 . It is also shown that the approximation ν(ν + 1) approximately equals (ν + 1/2) 2 which was used by some authors is not adequate below 30 Hz. Numerical results for both spherical and planar stratification show that (1) planar stratification is adequate for the computation of the lowest three ELF resonance frequencies to within 0.1 Hz; (2) planar stratification will lead to errors in cavity Q and wave attenuation which increase with frequency; (3) computation of resonance frequencies to within 0.1 Hz requires the extension of the lower boundary of the ionosphere to a height where the ratio of conduction current to displacement current, (sigma/ωepsilon 0 ), is less than 0.3; (4) atmospheric conductivity should be considered down to ground level in computing cavity Q and wave attenuation

  6. Materials for superconducting cavities

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  7. RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES

    Johnson, Rolland

    2014-09-21

    1.3 GHz RF test cell capable of operating both at high pressure and in vacuum with replaceable electrodes was designed, built, and power tested in preparation for testing the frequency and geometry effects of RF breakdown at Argonne National Lab. At the time of this report this cavity is still waiting for the 1.3 GHz klystron to be available at the Wakefield Test Facility. (3) Under a contract with Los Alamos National Lab, an 805 MHz RF test cavity, known as the All-Seasons Cavity (ASC), was designed and built by Muons, Inc. to operate either at high pressure or under vacuum. The LANL project to use the (ASC) was cancelled and the testing of the cavity has been continued under the grant reported on here using the Fermilab Mucool Test Area (MTA). The ASC is a true pillbox cavity that has performed under vacuum in high external magnetic field better than any other and has demonstrated that the high required accelerating gradients for many muon cooling beam line designs are possible. (4) Under ongoing support from the Muon Acceleration Program, microscopic surface analysis and computer simulations have been used to develop models of RF breakdown that apply to both pressurized and vacuum cavities. The understanding of RF breakdown will lead to better designs of RF cavities for many applications. An increase in the operating accelerating gradient, improved reliability and shorter conditioning times can generate very significant cost savings in many accelerator projects.

  8. Experimental investigation of cavity flows

    Loeland, Tore

    1999-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  9. Experimental investigation of cavity flows

    Loeland, Tore

    1998-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  10. High sensitivity detection of NO2 employing cavity ringdown spectroscopy and an external cavity continuously tunable quantum cascade laser.

    Rao, Gottipaty N; Karpf, Andreas

    2010-09-10

    A trace gas sensor for the detection of nitrogen dioxide based on cavity ringdown spectroscopy (CRDS) and a continuous wave external cavity tunable quantum cascade laser operating at room temperature has been designed, and its features and performance characteristics are reported. By measuring the ringdown times of the cavity at different concentrations of NO(2), we report a sensitivity of 1.2 ppb for the detection of NO(2) in Zero Air.

  11. A 201-MHz Normal Conducting RF Cavity for the International MICE Experiment

    Li, D.; DeMello, A.J.; Virostek, Steve; Zisman, Michael S.; Rimmer, Robert

    2008-01-01

    MICE is a demonstration experiment for the ionization cooling of muon beams. Eight RF cavities are proposed to be used in the MICE cooling channel. These cavities will be operated in a strong magnetic field; therefore, they must be normal conducting. The cavity design and construction are based on the successful experience and techniques developed for a 201-MHz prototype cavity for the US MUCOOL program. Taking advantage of a muon beamΛ s penetration property, the cavity employs a pair of curved thin beryllium windows to terminate conventional beam irises and achieve higher cavity shunt impedance. The cavity resembles a round, closed pillbox cavity. Two half-shells spun from copper sheets are joined by e-beam welding to form the cavity body. There are four ports on the cavity equator for RF couplers, vacuum pumping and field probes. The ports are formed by means of an extruding technique.

  12. Multi-Mode Cavity Accelerator Structure

    Jiang, Yong; Hirshfield, Jay Leonard

    2016-01-01

    This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10"-"7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise Δ T. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field E_s_u_r"m"a"x< 260 MV/m and pulsed surface heating Δ T"m"a"x< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power - as compared with operation at the same acceleration gradient using only the fundamental mode.

  13. Multi-Mode Cavity Accelerator Structure

    Jiang, Yong [Yale Univ., New Haven, CT (United States); Hirshfield, Jay Leonard [Omega-P R& D, Inc., New Haven, CT (United States)

    2016-11-10

    This project aimed to develop a prototype for a novel accelerator structure comprising coupled cavities that are tuned to support modes with harmonically-related eigenfrequencies, with the goal of reaching an acceleration gradient >200 MeV/m and a breakdown rate <10-7/pulse/meter. Phase I involved computations, design, and preliminary engineering of a prototype multi-harmonic cavity accelerator structure; plus tests of a bimodal cavity. A computational procedure was used to design an optimized profile for a bimodal cavity with high shunt impedance and low surface fields to maximize the reduction in temperature rise ΔT. This cavity supports the TM010 mode and its 2nd harmonic TM011 mode. Its fundamental frequency is at 12 GHz, to benchmark against the empirical criteria proposed within the worldwide High Gradient collaboration for X-band copper structures; namely, a surface electric field Esurmax< 260 MV/m and pulsed surface heating ΔTmax< 56 °K. With optimized geometry, amplitude and relative phase of the two modes, reductions are found in surface pulsed heating, modified Poynting vector, and total RF power—as compared with operation at the same acceleration gradient using only the fundamental mode.

  14. Multipactors in klystron cavities

    Hayashi, Kazutaka; Iyeki, Hiroshi; Kikunaga, Toshiyuki.

    1993-01-01

    A multipactor phenomenon in a klystron causes gain shortage or instability problem. Some tests using a prototype klystron input cavity revealed the microwave discharges in vacuum with magnetic field. The test results and the methods to avoid multipactors are discussed in this paper. (author)

  15. What's a Cavity?

    ... and deeper over time. Cavities are also called dental caries (say: KARE-eez), and if you have a ... made up mostly of the germs that cause tooth decay. The bacteria in your mouth make acids and when plaque clings to your teeth, the acids can eat away at the outermost ...

  16. Vertical cavity laser

    2016-01-01

    The present invention provides a vertical cavity laser comprising a grating layer comprising an in-plane grating, the grating layer having a first side and having a second side opposite the first side and comprising a contiguous core grating region having a grating structure, wherein an index...

  17. Oral cavity and jaw

    Solntsev, A.M.; Koval', G.Yu.

    1984-01-01

    Radioanatome of oral cavity and jaw is described. Diseases of the teeth, jaw, large salivary glands, temporo-mandibular articulation are considered. Roentgenograms of oral cacity and jaw of healthy people are presented and analyzed as well as roentgenograms in the above-mentioned diseases

  18. Niobium superconducting cavity

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  19. Cavity Nesting Birds

    Virgil E. Scott; Keith E. Evans; David R. Patton; Charles P. Stone

    1977-01-01

    Many species of cavity-nesting birds have declined because of habitat reduction. In the eastern United States, where primeval forests are gone, purple martins depend almost entirely on man-made nesting structures (Allen and Nice 1952). The hole-nesting population of peregrine falcons disappeared with the felling of the giant trees upon which they depended (Hickey and...

  20. LEP superconducting cavity

    1995-01-01

    Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.

  1. Open microwave cavities

    Šeba, Petr; Rotter, I.; Mueller, M.; Persson, C.; Pichugin, Konstantin N.

    2001-01-01

    Roč. 9, - (2001), s. 484-487 ISSN 1386-9477 Institutional research plan: CEZ:A02/98:Z1-010-914 Keywords : microwave cavity * resonances Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.009, year: 2001

  2. Filling a Conical Cavity

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  3. RF Power Requirements for PEFP SRF Cavity Test

    Kim, Han Sung; Seol, Kyung Tae; Kwon, Hyeok Jung; Cho, Yong Sub

    2011-01-01

    For the future extension of the PEFP (Proton Engineering Frontier Project) Proton linac, preliminary study on the SRF (superconducting radio-frequency) cavity is going on including a five-cell prototype cavity development to confirm the design and fabrication procedures and to check the RF and mechanical properties of a low-beta elliptical cavity. The main parameters of the cavity are like followings. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m (1.21 Kilp.) - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Stiffening structure: Double ring - Effective length: 0.45 m For the test of the cavity at low temperature of 4.2 K, many subsystems are required such as a cryogenic system, RF system, vacuum system and radiation shielding. RF power required to generate accelerating field inside cavity depends on the RF coupling parameters of the power coupler and quality factor of the SRF cavity and the quality factor itself is affected by several factors such as operating temperature, external magnetic field level and surface condition. Therefore, these factors should be considered to estimate the required RF power for the SRF cavity test

  4. Investigation on computation of elliptical microwave plasma cavity

    Liao, Xiaoli; Liu, Hua; Zhang, Kai

    2008-12-01

    In recent years, the advance of the elliptical resonant cavity and focus cavity is known by many people. There are homogeneous and multipatternal virtues in the focus dimensional microwave field of the elliptical resonant cavity. It is very suitable for applying the low power microwave biological effect equipment. However, when designing the elliptical resonant cavity may meet the problems of complex and huge computation need to be solved. This paper proposed the simple way of approximate processing the Mathieu function. It can greatly simplify the difficulty and decrease the scale of computation. This method can satisfy the requirements of research and development within project permitted precision.

  5. Ring cavity for a Raman capillary waveguide amplifier

    Kurnit, N.A.

    1981-01-27

    A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

  6. Ring cavity for a Raman capillary waveguide amplifir

    Kurnit, N.A.

    1981-01-27

    A regenerative ring amplifier and regenerative ring oscillator are described which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO/sub 2/ laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplified Stokes signal is synchronous with the mode-locked spikes of the incoming CO/sub 2/ laser pump signal.

  7. Implosion of the small cavity and large cavity cannonball targets

    Nishihara, Katsunobu; Yamanaka, Chiyoe.

    1984-01-01

    Recent results of cannonball target implosion research are briefly reviewed with theoretical predictions for GEKKO XII experiments. The cannonball targets are classified into two types according to the cavity size ; small cavity and large cavity. The compression mechanisms of the two types are discussed. (author)

  8. M10.3.1: LHC crab cavity specifications completed

    Ciapala, E

    2010-01-01

    • The starting point of Sub-task 1 is to determine the full LHC system requirements for the crab cavity system. This milestone concerns completion of basic specifications for the crab cavity system. This comprises the beam requirements, the cavity impedance constraints, the operating conditions and constraints, the layout and integration constraints in LHC and very importantly machine protection issues. The specifications of the cavity itself and its ancillaries follow from these system requirements and on the technology chosen for the cavity design. • The beam requirements result from the known parameters of the LHC upgrade lattice and the expected LHC beam parameters at ultimate bunch intensity. There are boundary conditions imposed by certain beam parameters such as the bunch length and intensity and by the machine layout, mainly the available beam pipe separations at the proposed cavity positions. Requirements on RF noise and stability are tight, to avoid emittance blow-up. Machine protection issues a...

  9. Frequency-tunable SRF cavities for microwave opto-mechanics

    Castelli, Alessandro; Martinez, Luis; Pate, Jacob; Thompson, Johnathon; Chiao, Raymond; Sharping, Jay

    Three dimensional SRF (Superconducting Radio Frequency) cavities are known for achieving high quality factors (Q =109 or higher) but suffer from limited frequency tunability once fabricated and cooled to superconducting temperatures. Our end-wall design allows for numerous applications of cavity tuning at temperatures as low as 40 millikelvin. Using a bimorphic piezoelectric transducer, we demonstrate approximately 15 MHz of resonance tunability for the TE011 mode at cryogenic temperatures in a cylindrical reactor grade niobium (Nb) cavity (10% of the range at room temperature). This range doubles when using tunable end-walls on both cavity ends. We report on techniques for improving the Q of multi-component cavities including the use of concave end-walls to reduce fields near the cylinder ends and indium O-rings to reduce resistive losses at the gaps. Three-dimensional SRF cavities of this type have potential applications to quantum information science, precision displacement metrology, and quantum electro-dynamics.

  10. 201 MHz Cavity R and D for MUCOOL and MICE

    Li, Derun; Virostek, Steve; Zisman, Michael; Norem, Jim; Bross, Alan; Moretti, Alfred; Norris, Barry; Torun, Yagmur; Phillips, Larry; Rimmer, Robert; Stirbet, Mircea; Reep, Michael; Summers, Don

    2006-01-01

    We describe the design, fabrication, analysis and preliminary testing of the prototype 201 MHz copper cavity for a muon ionization cooling channel. Cavity applications include the Muon Ionization Cooling Experiment (MICE) as well as cooling channels for a neutrino factory or a muon collider. This cavity was developed by the US muon cooling (MUCOOL) collaboration and is being tested in the MUCOOL Test Area (MTA) at Fermilab. To achieve a high accelerating gradient, the cavity beam irises are terminated by a pair of curved, thin beryllium windows. Several fabrication methods developed for the cavity and windows are novel and offer significant cost savings as compared to conventional construction methods. The cavity's thermal and structural performances are simulated with an FEA model. Preliminary high power RF commissioning results will be presented

  11. Technical evaluation of corium cooling at the reactor cavity

    Yang, Soo Hyung; Chan, Eun Sun; Lee, Jae Hun; Lee, Jong In

    1998-01-01

    To terminate the progression of the severe accident and mitigate the accident consequences, corium cooling has been suggested as one of most important design features considered in the severe accident mitigation. Till now, some kinds of cooling methodologies have been identified and, specially, the corium cooling at the reactor cavity has been considered as one of the most promising cooling methodologies. Moreover, several design requirements related to the corium cooling at the reactor cavity have been also suggested and applied to the design of the next generation reactor. In this study, technical descriptions are briefly described for the important issues related to the corium cooling at the reactor cavity, i.e. cavity area, cavity flooding system, etc., and simple evaluations for those items have been performed considering present technical levels including the experiment and analytical works

  12. Deep-ultraviolet cavity ringdown spectroscopy

    Sneep, M.C.; Hannemann, S.; van Duijn, E.J.; Ubachs, W.M.G.

    2004-01-01

    The sensitive optical detection technique of cavity ringdown spectroscopy is extended to the wavelength range 197-204 nm. A novel design narrowband Fourier-transform-limited laser is used, and the technique is applied to gas-phase extinction measurements in CO

  13. Lambda shifted photonic crystal cavity laser

    Schubert, Martin; Skovgård, Troels Suhr; Ek, Sara

    2010-01-01

    We propose and demonstrate an alternative type of photonic crystal laser design that shifts all the holes in the lattice by a fixed fraction of the targeted emission wavelength. The structures are realized in InGaAsP =1.15 with InGaAsP quantum wells =1.52 as gain material. Cavities with shifts of...

  14. Electroacoustic oscillations in the LEP SC. cavities

    Boussard, Daniel; Tückmantel, Joachim

    1996-01-01

    The LEP superconducting cavities have been plagued by electroacoustic oscillations. Tests have been done to eliminate these by a special feed-back loop in the tuning circuit as well as a feed-forward path, but they could only be eliminated safely up to the design field by running the cavities close to tune neglecting beam-loading compensation. This technique proved successful during the first LEP2 test run at 70 GeV. The mechanism and essential parameters driving these oscillations have been analysed as well as the corresponding stronger loading of the power coupler.

  15. Strategies for waveguide coupling for SRF cavities

    Doolittle, L.R.

    1998-01-01

    Despite widespread use of coaxial couplers in SRF cavities, a single, simple waveguide coupling can be used both to transmit generator power to a cavity, and to remove a large class of Higher Order Modes (HOMs, produced by the beam). There are balances and tradeoffs to be made, such as the coupling strength of the various frequencies, the transverse component of the coupler fields on the beam axis, and the magnitude of the surface fields and currents. This paper describes those design constraints, categories of solutions, and examples from the CEBAF Energy Upgrade studies

  16. Accelerating RF cavity of the Booster

    CERN PhotoLab

    1981-01-01

    Each of the 4 PS Booster rings has a single accelerating cavity. It consists of 2 quarter-wave ferrite-loaded resonators. There are 2 figure-of-eight loops on the ferrite loads for tuning the frequency throughout the acceleration cycle, from 3 to 8 MHz (from 50 MeV at injection to the original Booster energy of 800 MeV, 2 GeV today). The cavities have a flat design, to fit the ring-to-ring distance of 36 cm. The tube for forced-air cooling is visible in the left front. See also 8301084.

  17. Accelerating RF cavity of the Booster

    CERN PhotoLab

    1983-01-01

    Each of the 4 PS Booster rings has a single accelerating cavity.It consists of 2 quarter-wave ferrite-loaded resonators. 2 figure-of-eight loops tune the frequency throughout the accelerating cycle, from 3 to 8 MHz (from 50 MeV at injection to the original Booster energy of 800 MeV, 2 GeV today). The cavities have a flat design, to fit the ring-to-ring distance of 36 cm, and are forced-air cooled. The 2 round objects in the front-compartments are the final-stage power-tetrodes. See also 8111095.

  18. Cryogenic system for TRISTAN superconducting RF cavity

    Hosoyama, K.; Hara, K.; Kabe, A.; Kojima, Yuuji; Ogitsu, T.; Sakamoto, Y.; Kawamura, S.; Ishimaru, Y.

    1990-01-01

    A cryogenic system consisting of a helium refrigerator (4 kW at 4.4 K) and a liquid helium distribution transfer system for TRISTAN 508 MHz 32 x 5-cell superconducting RF cavities was designed and constructed. After the performance test of the cryogenic system, 16 x 5-cell superconducting RF cavities in 8 cryostats were installed in underground TRISTAN electron-positron collider and connected to the helium refrigerator on the ground level through the transfer line (total length about 330 m) and cooled by liquid helium pool boiling in parallel. The cryogenic system and its operation experience are described. (author)

  19. Hollow waveguide cavity ringdown spectroscopy

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  20. Nuclear reactor cavity streaming shield

    Klotz, R.J.; Stephen, D.W.

    1978-01-01

    The upper portion of a nuclear reactor vessel supported in a concrete reactor cavity has a structure mounted below the top of the vessel between the outer vessel wall and the reactor cavity wall which contains hydrogenous material which will attenuate radiation streaming upward between vessel and the reactor cavity wall while preventing pressure buildup during a loss of coolant accident

  1. Superconducting Cavity Development for the CEBAF Upgrade

    I.E. Campisi; J.R. Delayen; L.R. Doolittle; P.Kneisel; J. Mammosser; L. Phillips

    1999-01-01

    Long-term plans for CEBAF at Jefferson Lab call for achieving 12 GeV in the middle of the next decade and 24 GeV after 2010. In support of these plans, an Upgrade Cryomodule, capable of providing more than twice the operating voltage of the existing CEBAF modules within the same length, is being developed. In particular, this requires the development of superconducting cavities capable of consistently operating at gradients above 12 MV/m and Q approximately 10 10 . We have engaged in a complete review of all the processes and procedures involved in the fabrication and assembly of cavities, and are modifying our chemical processing, cleaning, and assembly facilities. While we have retained the cell shape of existing CEBAF cavities, the new superconducting structure will be substantially different in several respects, such as the higher-order-modes damping and the fundamental power coupling systems. Design features and experimental results will be presented

  2. PEP-II RF cavity revisited

    Rimmer, R.A.; Koehler, G.; Li, D.; Hartman, N.; Folwell, N.; Hodgson, J.; Ko, K.; McCandless, B.

    1999-01-01

    This report describes the results of numerical simulations of the PEP-II RF cavity performed after the completion of the construction phase of the project and comparisons are made to previous calculations and measured results. These analyses were performed to evaluate new calculation techniques for the HOM distribution and RF surface heating that were not available at the time of the original design. These include the use of a high frequency electromagnetic element in ANSYS and the new Omega 3P code to study wall losses, and the development of broadband time domain simulation methods in MAFIA for the HOM loading. The computed HOM spectrum is compared with cavity measurements and observed beam-induced signals. The cavity fabrication method is reviewed, with the benefit of hindsight, and simplifications are discussed

  3. Cavity Pressure Behaviour in Micro Injection Moulding

    Griffiths, C.A.; Dimov, S.S.; Scholz, S.

    2010-01-01

    as well as with the filling of the cavity by the polymer melt. In this paper, two parameters derived from cavity pressure over time (i.e. pressure work). The influence of four µIM parameters (melt temperature, mould temperature, injection speed, aand packing pressure) on the two pressure-related outputs...... has been investigated by moulding a micro fluidic component on three different polymers (PP, ABS, PC) using the design of experiment approach. Similar trends such as the effects of a higher injection speed in decreasing the pressure work and of a lower temperature in decreasing pressure rate have been......Process monitoring of micro injection moulding (µIM) is of crusial importance to analyse the effect of different parameter settings on the process and to assess its quality. Quality factors related to cavity pressure can provide useful information directly connected with the dyanmics of the process...

  4. Colloquium: cavity optomechanics

    2011-01-01

    Monday 14 November 2011, 17:00 Ecole de Physique, Auditoire Stueckelberg Université de Genève Cavity optomechanics: controlling micro mechanical oscillators with laser light Prof. Tobias Kippenberg EPFL, Lausanne Laser light can be used to cool and to control trapped ions, atoms and molecules at the quantum level. This has lead to spectacular advances such as the most precise atomic clocks. An outstanding frontier is the control with lasers of nano- and micro-mechancial systems. Recent advances in cavity optomechanics have allowed such elementary control for the first time, enabling mechanical systems to be ground state cooled leading to readout with quantum limited sensitivity and permitting to explore new device concepts resulting from radiation pressure.  

  5. Progress on the high-current 704 MHz superconducting RF cavity at BNL

    Xu, W.; Astefanous, C.; Belomestnykh, S.; Ben-Zvi, I.

    2012-01-01

    The 704 MHz high current superconducting cavity has been designed with consideration of both performance of fundamental mode and damping of higher order modes. A copper prototype cavity was fabricated by AES and delivered to BNL. RF measurements were carried out on this prototype cavity, including fundamental pass-band and HOM spectrum measurements, HOM studies using bead-pull setup, prototyping of antenna-type HOM couplers. The measurements show that the cavity has very good damping for the higher-order modes, which was one of the main goals for the high current cavity design. 3D cavity models were simulated with Omega3P code developed by SLAC to compare with the measurements. The paper describes the cavity design, RF measurement setups and results for the copper prototype. The progress with the niobium cavity fabrication will also be described.

  6. Leaching materials from cavities

    Hodgson, T.D.; Jordan, T.W.J.

    1980-01-01

    A material is leached from a cavity by contacting the material with a liquid and subjecting the liquid to a number of pressure cycles, each pressure cycle involving a decrease in pressure to cause boiling of the liquid, followed by a rise in pressure to inhibit the boiling. The method may include the step of heating the liquid to a temperature near to its boiling point. The material may be nuclear fuel pellets or calcium carbonate pellets. (author)

  7. Development of a high-power RF cavity for the PEP-II B factory

    Rimmer, R.A.; Allen, M.A.; Saba, J.; Schwarz, H.

    1995-03-01

    The authors describe the development and fabrication of the first high-power RF cavity for PEP-II. Design choices and fabrication technologies for the first cavity and subsequent production cavities are described. Conditioning and high-power testing of the first and subsequent cavities are discussed, as well as integration of the cavity into modular RF systems for both high-energy and low-energy rings. Plans for installation of the cavity raft assemblies in the RF sections of the PEP tunnel are also considered

  8. Three-dimensional self-consistent simulations of multipacting in superconducting radio frequency cavities. Final Report

    Nieter, Chet

    2010-01-01

    Superconducting radio frequency (SRF) cavities are a popular choice among researchers designing new accelerators because of the reduced power losses due to surface resistance. However, SRF cavities still have unresolved problems, including the loss of power to stray electrons. Sources of these electrons are field emission from the walls and ionization of background gas, but the predominant source is secondary emission yield (SEY) from electron impact. When the electron motion is in resonance with the cavity fields the electrons strike the cavity surface repeatedly creating a resonant build up of electrons referred to as multipacting. Cavity shaping has successfully reduced multipacting for cavities used in very high energy accelerators. However, multipacting is still a concern for the cavity power couplers, where shaping is not possible, and for cavities used to accelerate particles at moderate velocities. This Phase II project built upon existing models in the VORPAL simulation framework to allow for simulations of multipacting behavior in SRF cavities and their associated structures. The technical work involved allowed existing models of secondary electron generation to work with the complex boundary conditions needed to model the cavity structures. The types of data produced by VORPAL were also expanded to include data common used by cavity designers to evaluate cavity performance. Post-processing tools were also modified to provide information directly related to the conditions that produce multipacting. These new methods were demonstrated by running simulations of a cavity design being developed by researchers at Jefferson National Laboratory to attempt to identify the multipacting that would be an issue for the cavity design being considered. These simulations demonstrate that VORPAL now has the capabilities to assist researchers working with SRF cavities to understand and identify possible multipacting issues with their cavity designs.

  9. Experimental validation of a topology optimized acoustic cavity

    Christiansen, Rasmus Ellebæk; Sigmund, Ole; Fernandez Grande, Efren

    2015-01-01

    This paper presents the experimental validation of an acoustic cavity designed using topology optimization with the goal of minimizing the sound pressure locally for monochromatic excitation. The presented results show good agreement between simulations and measurements. The effect of damping...

  10. Design, construction, system integration, and test results of the 1 MW CW RF system for the e-gun cavity in the energy recovery LINAC at Brookhaven National Laboratory

    Lenci, S.J.; Eisen, E.L.; Dickey, D.L.; Sainz, J.E.; Utay, P.F.; Zaltsman, A.; Lambiase, R.

    2009-01-01

    Brookhaven's ERL (Energy Recovery LINAC) requires a 1 MW CW RF system for the superconducting electron gun cavity. The system consists primarily of a klystron tube, transmitter, and High-Voltage Power Supply (HVPS). The 703.75 MHz klystron made by CPl, Inc. provides RF power of 1MW CW with efficiency of 65%. It has a single output window, diode-type electron gun, and collector capable of dissipating the entire beam power. It was fully factory tested including 24-hour heat run at 1.1 MW CWo The solid state HVPS designed by Continental Electronics provides up to 100 kV at low ripple and 2.1 MW CW with over 95% efficiency. With minimal stored energy and a fast shut-down mode no crowbar circuit is needed. Continental 's transmitter includes PLC based user interface and monitoring, RF pre-amplifier, magnet and Vac-Ion pump supplies, cooling water instrumentation, and integral safety interlock system. BNL installed the klystron, HVPS, and transmitter along with other items, such as circulator, water load, and waveguide components. The collaboration of BNL, CPI, and Continental in the design, installation, and testing was essential to the successful operation of the 1MW system

  11. Fundamental Power Couplers for Superconducting Cavities

    Isidoro E. Campisi

    2001-01-01

    Fundamental power couplers (FPC's) for superconducting cavities must meet very strict requirements to perform at high power levels (hundreds of kilowatts) and in a variety of conditions (CS, pulsed, travelling wave, standing wave) without adversely affecting the performance of the cavities they are powering. Producing good coupler designs and achieving operational performances in accelerator environments are challenging tasks that have traditionally involved large resources from many laboratories. The designs involve state-of-the-art activities in RF, cryogenic and mechanical engineering, materials science, vacuum technology, and electromagnetic field modeling. Handling, assembly and conditioning procedures have been developed to achieve ever-increasing power levels and more reliable operation. In this paper, the technical issues associated with the design, construction, assembly, processing, and operation of FPC's will be reviewed, together with the progress in FPC activities in several laboratories during the past few years

  12. Pill-Box Cavity BPM For TESLA Cryomodul

    Sargsyan, V

    2003-01-01

    A new cavity BPM with 10 μm resolution is designed and fabricated to perform single bunch measurements at the TESLA linear collider. In order to have a low energy dissipation in the cryogenic supermodule, the inner surface of the cavity is copper plated. Cross-talk is minimised by a special polarisation design. The electronics, at 1.5 GHz, is a homodyne receiver normalised to the bunch charge. Its LO-signal for down-conversion is taken from the same cavity.

  13. Progress on a prototype main ring rf cavity

    Swain, G.; Kandarian, R.; Thiessen, H.A.; Poirier, R.; Smythe, W.R.

    1989-01-01

    A prototype rf cavity and rf drive system for a hadron facility main ring has been designed and will be tested in the Proton Storage Ring (PSR) at Los Alamos as a part of a collaborative effort between LANL and TRIUMF. The cavity uses an orthogonally biased ferrite tuner. The design provides for accelerating gap voltages up to 200 kV for the 49.3 to 50.8 MHz range. Progress on the cavity construction and testing is described. 13 refs., 5 figs

  14. ISR RF cavities

    1983-01-01

    In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

  15. Development of superconducting RF cavity at 1050 MHz frequency for an electron LINAC

    Sarkar, S.G.; Mondal, J.; Mittal, K.C.

    2011-01-01

    This paper reports the design of a prototype superconducting cavity at 1050 MHz and design of associated die punch and machining fixtures for the cavity fabrication. The cavity is of β= 1 and elliptical in shape. The circle-straight line-ellipse-type structure design has been optimized by 'SUPERFISH' - a 2 dimensional code for cavity tuning. The 3 Dimensional EM field analysis of the cavity structure has been done using 'CST' software. The ratio of the maximum surface electric field to the accelerating gradient, E pk /E acc , is optimised to 1.984 and H pk /E acc is optimised to 4.141 mT/(MV/m). Bore radius of the cavity has been chosen such a way so that the cell-to-cell coupling remains as high as 1.85%. The cavity is designed to achieve 25 MV/m accelerating gradient. (author)

  16. Femtojoule-scale all-optical latching and modulation via cavity nonlinear optics.

    Kwon, Yeong-Dae; Armen, Michael A; Mabuchi, Hideo

    2013-11-15

    We experimentally characterize Hopf bifurcation phenomena at femtojoule energy scales in a multiatom cavity quantum electrodynamical (cavity QED) system and demonstrate how such behaviors can be exploited in the design of all-optical memory and modulation devices. The data are analyzed by using a semiclassical model that explicitly treats heterogeneous coupling of atoms to the cavity mode. Our results highlight the interest of cavity QED systems for ultralow power photonic signal processing as well as for fundamental studies of mesoscopic nonlinear dynamics.

  17. Analysis and design of tunable wideband microwave photonics phase shifter based on Fabry-Perot cavity and Bragg mirrors in silicon-on-insulator waveguide.

    Qu, Pengfei; Zhou, Jingran; Chen, Weiyou; Li, Fumin; Li, Haibin; Liu, Caixia; Ruan, Shengping; Dong, Wei

    2010-04-20

    We designed a microwave (MW) photonics phase shifter, consisting of a Fabry-Perot filter, a phase modulation region (PMR), and distributed Bragg reflectors, in a silicon-on-insulator rib waveguide. The thermo-optics effect was employed to tune the PMR. It was theoretically demonstrated that the linear MW phase shift of 0-2pi could be achieved by a refractive index variation of 0-9.68x10(-3) in an ultrawideband (about 38?GHz-1.9?THz), and the corresponding tuning resolution was about 6.92 degrees / degrees C. The device had a very compact size. It could be easily integrated in silicon optoelectronic chips and expected to be widely used in the high-frequency MW photonics field.

  18. Oral cavity eumycetoma

    Gisele Alborghetti Nai

    2011-06-01

    Full Text Available Mycetoma is a pathological process in which eumycotic (fungal or actinomycotic causative agents from exogenous source produce grains. It is a localized chronic and deforming infectious disease of subcutaneous tissue, skin and bones. We report the first case of eumycetoma of the oral cavity in world literature. CASE REPORT: A 43-year-old male patient, complaining of swelling and fistula in the hard palate. On examination, swelling of the anterior and middle hard palate, with fistula draining a dark liquid was observed. The panoramic radiograph showed extensive radiolucent area involving the region of teeth 21-26 and the computerized tomography showed communication with the nasal cavity, suggesting the diagnosis of periapical cyst. Surgery was performed to remove the lesion. Histopathological examination revealed purulent material with characteristic grain. Gram staining for bacteria was negative and Grocott-Gomori staining for the detection of fungi was positive, concluding the diagnosis of eumycetoma. The patient was treated with ketoconazole for nine months, and was considered cured at the end of treatment. CONCLUSION: Histopathological examination, using histochemical staining, and direct microscopic grains examination can provide the distinction between eumycetoma and actinomycetoma accurately.

  19. Preliminary Results from a Superconducting Photocathode Sample Cavity

    Kneisel, Peter; Lipski, Andrzej; Sekutowicz, Jacek

    2005-01-01

    Pure niobium has been proposed as a photocathode material and recently a successful test has been conducted with a niobium single cell cavity to extract photo-currents from the surface of this cavity. However, the quantum efficiency of niobium is ~2·10-4, whereas electrodeposited lead has a ~15 times higher quantum efficiency. We have designed and tested a photo-injector niobium cavity, which can be used to insert photo-cathodes made of different materials in the high electric field region of the cavity. Experiments have been conducted with niobium and lead, which show that neither the Q- values of the cavity nor the obtainable surface fields are significantly lowered. This paper reports about the results from these tests.

  20. Thermal Model of a Dish Stirling Cavity-Receiver

    Rubén Gil

    2015-01-01

    Full Text Available This paper presents a thermal model for a dish Stirling cavity based on the finite differences method. This model is a theoretical tool to optimize the cavity in terms of thermal efficiency. One of the main outcomes of this work is the evaluation of radiative exchange using the radiosity method; for that purpose, the view factors of all surfaces involved have been accurately calculated. Moreover, this model enables the variation of the cavity and receiver dimensions and the materials to determine the optimal cavity design. The tool has been used to study the cavity optimization regarding geometry parameters and material properties. Receiver absorptivity has been identified as the most influential property of the materials. The optimal aperture height depends on the minimum focal space.

  1. Fabrication and Testing of Deflecting Cavities for APS

    Mammosser, John; Wang, Haipeng; Rimmer, Robert; Jim, Henry; Katherine, Wilson; Dhakal, Pashupati; Ali, Nassiri; Jim, Kerby; Jeremiah, Holzbauer; Genfa, Wu; Joel, Fuerst; Yawei, Yang; Zenghai, Li

    2013-09-01

    Jefferson Lab (Newport News, Virginia) in collaboration with Argonne National Laboratory (Argonne, IL) has fabricated and tested four first article, 2.8 GHz, deflecting SRF cavities, for Argonne's Short-Pulse X-ray (SPX) project. These cavities are unique in many ways including the fabrication techniques in which the cavity cell and waveguides were fabricated. These cavity subcomponents were milled from bulk large grain niobium ingot material directly from 3D CAD files. No forming of sub components was used with the exception of the beam-pipes. The challenging cavity and helium vessel design and fabrication results from the stringent RF performance requirements required by the project and operation in the APS ring. Production challenges and fabrication techniques as well as testing results will be discussed in this paper.

  2. Superconducting Radio-Frequency Cavities

    Padamsee, Hasan S.

    2014-10-01

    Superconducting cavities have been operating routinely in a variety of accelerators with a range of demanding applications. With the success of completed projects, niobium cavities have become an enabling technology, offering upgrade paths for existing facilities and pushing frontier accelerators for nuclear physics, high-energy physics, materials science, and the life sciences. With continued progress in basic understanding of radio-frequency superconductivity, the performance of cavities has steadily improved to approach theoretical capabilities.

  3. Low energy booster radio frequency cavity structural analysis

    Jones, K.

    1994-01-01

    The structural design of the Superconducting Super Collider Low Energy Booster (LEB) Radio Frequency (RF) Cavity is very unique. The cavity is made of three different materials which all contribute to its structural strength while at the same time providing a good medium for magnetic properties. Its outer conductor is made of thin walled stainless steel which is later copper plated to reduce the electrical losses. Its tuner housing is made of a fiber reinforced composite laminate, similar to G10, glued to stainless steel plating. The stainless steel of the tuner is slotted to significantly diminish the magnetically-induced eddy currents. The composite laminate is bonded to the stainless steel to restore the structural strength that was lost in slotting. The composite laminate is also a barrier against leakage of the pressurized internal ferrite coolant fluid. The cavity's inner conductor, made of copper and stainless steel, is subjected to high heat loads and must be liquid cooled. The requirements of the Cavity are very stringent and driven primarily by deflection, natural frequency and temperature. Therefore, very intricate finite element analysis was used to complement conventional hand analysis in the design of the cavity. Structural testing of the assembled prototype cavity is planned to demonstrate the compliance of the cavity design to all of its requirements

  4. Low energy booster radio frequency cavity structural analysis

    Jones, K.

    1993-04-01

    The structural design of the Superconducting Super Collider Low Energy Booster (LEB) Radio Frequency (RF) Cavity is very unique. The cavity is made of three different materials which all contribute to its structural strength while at the same time providing a good medium for magnetic properties. Its outer conductor is made of thin walled stainless steel which is later copper plated to reduce the electrical losses. Its tuner housing is made of a fiber reinforced composite laminate, similar to G10, glued to stainless steel plating. The stainless steel of the tuner is slotted to significantly diminish the magnetically-induced eddy currents. The composite laminate is bonded to the stainless steel to restore the structural strength that was lost in slotting. The composite laminate is also a barrier against leakage of the pressurized internal ferrite coolant fluid. The cavity's inner conductor, made of copper and stainless steel, is subjected to high heat loads and must be liquid cooled. The requirements of the Cavity are very stringent and driven primarily by deflection, natural frequency and temperature. Therefore, very intricate finite element analysis was used to complement conventional hand analysis in the design of the cavity. Structural testing of the assembled prototype cavity is planned to demonstrate the compliance of the cavity design to all of its requirements

  5. Operating experience with superconducting cavities at Jefferson Lab

    Reece, C.E.

    1998-01-01

    The CEBAF recirculating superconducting electron linac at Jefferson Lab is now in full operation supporting nuclear physics experiments in three target halls at up to 4.4 GeV. The 330 SRF cavities, operating at 2.0 K, continue to perform well above design specifications, and have accumulated over 8,000,000 operating cavity hours. The authors have to date no evidence of degradation of cavity performance. The SRF cavities have demonstrated excellent reliability. The one klystron per cavity design provides CEBAF with flexibility and redundancy for normal operations. Several techniques have been developed for establishing optimum operating conditions for the 330 independent systems. Operation of the cavities and control systems at the full design current of 1 mA has recently been achieved. The principal constraints on usable gradient for low current operations are (1) discharge at the cold ceramic rf window induced by electron field emission in cavities, (2) tuner controls, and (3) stability of the waveguide vacuum in the region between the warm and cold windows. Several cryomodules have been improved by application of rf helium processing while installed on the beamline

  6. CEBAF: Accelerating cavities look good

    Anon.

    1990-09-15

    The first assembled pairs of superconducting accelerating cavities from German supplier Interatom for the Continuous Electron Beam Accelerator Facility, Newport News, Virginia, have exceeded performance specifications.

  7. CEBAF: Accelerating cavities look good

    Anon.

    1990-01-01

    The first assembled pairs of superconducting accelerating cavities from German supplier Interatom for the Continuous Electron Beam Accelerator Facility, Newport News, Virginia, have exceeded performance specifications

  8. Multipacting studies in elliptic SRF cavities

    Prakash, Ram; Jana, Arup Ratan; Kumar, Vinit

    2017-09-01

    Multipacting is a resonant process, where the number of unwanted electrons resulting from a parasitic discharge rapidly grows to a larger value at some specific locations in a radio-frequency cavity. This results in a degradation of the cavity performance indicators (e.g. the quality factor Q and the maximum achievable accelerating gradient Eacc), and in the case of a superconducting radiofrequency (SRF) cavity, it leads to a quenching of superconductivity. Numerical simulations are essential to pre-empt the possibility of multipacting in SRF cavities, such that its design can be suitably refined to avoid this performance limiting phenomenon. Readily available computer codes (e.g.FishPact, MultiPac,CST-PICetc.) are widely used to simulate the phenomenon of multipacting in such cases. Most of the contemporary two dimensional (2D) codes such as FishPact, MultiPacetc. are unable to detect the multipacting in elliptic cavities because they use a simplistic secondary emission model, where it is assumed that all the secondary electrons are emitted with same energy. Some three-dimensional (3D) codes such as CST-PIC, which use a more realistic secondary emission model (Furman model) by following a probability distribution for the emission energy of secondary electrons, are able to correctly predict the occurrence of multipacting. These 3D codes however require large data handling and are slower than the 2D codes. In this paper, we report a detailed analysis of the multipacting phenomenon in elliptic SRF cavities and development of a 2D code to numerically simulate this phenomenon by employing the Furman model to simulate the secondary emission process. Since our code is 2D, it is faster than the 3D codes. It is however as accurate as the contemporary 3D codes since it uses the Furman model for secondary emission. We have also explored the possibility to further simplify the Furman model, which enables us to quickly estimate the growth rate of multipacting without

  9. Construction of the LITL cavity structure

    Itoh, S.; Masuda, S.; Ukai, Y.; Hirao, Y.

    1984-01-01

    This report presents briefly the mechanical consideration for the 100 MHz four-vane RFQ (radio frequency quadrupole accelerator) structure construction. At first, the theoretical vane shape required to obtain the RFQ electric field distribution was determined. A numerically controlled milling machine was employed for the precise machining of the complicated shape. The data sets for NC machining and for checking the size of three-dimensional coordinates were made up. A small vane model was machined by way of trial experiment to check the data to verify the circular interpolation programmed NC machining method, and to investigate cutter interference. The errors in the measurement in machining were less than +- 30 micrometer. The resonator tank is 56 cm in inner diameter and 138 cm in length, and is made of mild steel of 35 mm thickness. The inside wall was plated with copper thickly. Various conditions for the copper plating were investigated. Four vanes were assembled within the cavity of the RFQ. The vanes were built in the cavity tank with high dimensional accuracy. It was a matter of primary concern to design acceptable mechanical rf joints and select suitable rf contact elements for a high Q value of the RFQ resonator cavity. Finally, the Q value was measured, and was 10,600. The cavity was able to be evacuated to 10 -7 Torr. (Kato, T.)

  10. Aero-Heating of Shallow Cavities in Hypersonic Freestream Flow

    Everhart, Joel L.; Berger, Karen T.; Merski, N. R., Jr.; Woods, William A.; Hollingsworth, Kevin E.; Hyatt, Andrew; Prabhu, Ramadas K.

    2010-01-01

    The purpose of these experiments and analysis was to augment the heating database and tools used for assessment of impact-induced shallow-cavity damage to the thermal protection system of the Space Shuttle Orbiter. The effect of length and depth on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These rapid-response experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated immediately prior to the launch of STS-114, the initial flight in the Space Shuttle Return-To-Flight Program, and continued during the first week of the mission. Previously-designed and numerically-characterized blunted-nose baseline flat plates were used as the test surfaces. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process and the two-dimensional flow assumptions used for the data analysis. The experimental boundary layer state conditions were inferred using the measured heating distributions on a no-cavity test article. Two test plates were developed, each containing 4 equally-spaced spanwise-distributed cavities. The first test plate contained cavities with a constant length-to-depth ratio of 8 with design point depth-to-boundary-layer-thickness ratios of 0.1, 0.2, 0.35, and 0.5. The second test plate contained cavities with a constant design point depth-to-boundary-layer-thickness ratio of 0.35 with length-to-depth ratios of 8, 12, 16, and 20. Cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary results indicate that the floor-averaged Bump Factor (local heating rate nondimensionalized by upstream reference) at the tested conditions is approximately 0.3 with a standard deviation of 0.04 for laminar-in/laminar-out conditions when the cavity length-to-boundary-layer thickness is between 2.5 and 10 and for

  11. Subharmonic response of a single-degree-of-freedom nonlinear vibro-impact system to a narrow-band random excitation.

    Haiwu, Rong; Wang, Xiangdong; Xu, Wei; Fang, Tong

    2009-08-01

    The subharmonic response of single-degree-of-freedom nonlinear vibro-impact oscillator with a one-sided barrier to narrow-band random excitation is investigated. The narrow-band random excitation used here is a filtered Gaussian white noise. The analysis is based on a special Zhuravlev transformation, which reduces the system to one without impacts, or velocity jumps, thereby permitting the applications of asymptotic averaging over the "fast" variables. The averaged stochastic equations are solved exactly by the method of moments for the mean-square response amplitude for the case of linear system with zero offset. A perturbation-based moment closure scheme is proposed and the formula of the mean-square amplitude is obtained approximately for the case of linear system with nonzero offset. The perturbation-based moment closure scheme is used once again to obtain the algebra equation of the mean-square amplitude of the response for the case of nonlinear system. The effects of damping, detuning, nonlinear intensity, bandwidth, and magnitudes of random excitations are analyzed. The theoretical analyses are verified by numerical results. Theoretical analyses and numerical simulations show that the peak amplitudes may be strongly reduced at large detunings or large nonlinear intensity.

  12. Technical tasks in superconducting cavities

    Saito, Kenji [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    1997-11-01

    The feature of superconducting rf cavities is an extremely small surface resistance on the wall. It brings a large energy saving in the operation, even those are cooled with liquid helium. That also makes possible to operate themselves in a higher field gradient comparing to normal conducting cavities, and brings to make accelerators compact. These merits are very important for the future accelerator engineering which is planed at JAERI for the neutron material science and nuclear waste transmutation. This machine is a high intensity proton linac and uses sc cavities in the medium and high {beta} sections. In this paper, starting R and D of proton superconducting cavities, several important technical points which come from the small surface resistance of sc cavities, are present to succeed it and also differences between the medium and high - {beta} structures are discussed. (author)

  13. Tunneling effect in cavity-resonator-coupled arrays

    Ma Hua; Xu Zhuo; Qu Shao-Bo; Zhang Jie-Qiu; Wang Jia-Fu; Liang Chang-Hong

    2013-01-01

    The quantum tunneling effect (QTE) in a cavity-resonator-coupled (CRC) array was analytically and numerically investigated. The underlying mechanism was interpreted by treating electromagnetic waves as photons, and then was generalized to acoustic waves and matter waves. It is indicated that for the three kinds of waves, the QTE can be excited by cavity resonance in a CRC array, resulting in sub-wavelength transparency through the narrow splits between cavities. This opens up opportunities for designing new types of crystals based on CRC arrays, which may find potential applications such as quantum devices, micro-optic transmission, and acoustic manipulation. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. Calculation of mechanical vibration frequencies of stiffened superconducting cavities

    Black, S.J.; Spalek, G.

    1992-01-01

    We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL- modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations

  15. HFSS Simulation on Cavity Coupling for Axion Detecting Experiment

    Yeo, Beomki

    2015-01-01

    In the resonant cavity experiment, it is vital maximize signal power at detector with the minimized reflection from source. Return loss is minimized when the impedance of source and cavity are matched to each other and this is called impedance matching. Establishing tunable antenna on source is required to get a impedance matching. Geometry and position of antenna is varied depending on the electromagnetic eld of cavity. This research is dedicated to simulation to nd such a proper design of coupling antenna, especially for axion dark matter detecting experiment. HFSS solver was used for the simulation.

  16. Calculation of mechanical vibration frequencies of stiffened superconducting cavities

    Black, S.J.; Spalek, G.

    1992-01-01

    We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL-modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations. (Author) 6 figs., 5 tabs., 4 refs

  17. RF-cavity for the X-ray generator NESTOR

    Androsov, V.P.; Gvozd, A.M.; Karnaukhov, I.M.; Telegin, Yu.N.; Chernov, K.N.; Ostreyko, G.N.; Sedlyarov, I.K.

    2007-01-01

    In the Kharkov Institute of Physics and Technology 225 MeV electron storage ring NESTOR is under development. The paper describes the design and parameters of a 700 MHz cavity that has been fabricated at BINP for the NESTOR RF-system. Now the low-power and vacuum tests of the cavity are under way at BINP. We present here the results of 3D simulations of the cavity with ANSYS code. The problem of multibunch instabilities in NESTOR is also discussed

  18. The DAΦNE 3RD harmonic cavity

    Alesini, D.; Boni, R.; Clozza, A.; Gallo, A.; Guiducci, S.; Marcellini, F.; Migliorati, M.; Palumbo, L.; Pellegrino, L.; Sgamma, F.; Zobov, M.

    2001-01-01

    The installation of a passive 3rd harmonic cavity in both the e + and e - rings of the Frascati Φ-factory DAΦNE has been decided in order to improve the Touschek lifetime by increasing the bunch length. The implications of the RF harmonic system on the beam dynamics, in particular those related to the gap in the bunch filling pattern, have been carefully studied by means of analytical and numerical tools. A single-cell cavity incorporating a ferrite ring for the HOM damping has been designed through the extensive use of MAFIA and HFSS simulation codes. One cavity prototype has been built and extensively bench tested, while the fabrication of the two final cavities is almost completed. A description of the design and construction activities, and a set of experimental measurements are reported in this paper

  19. Superconducting Prototype Cavities for the Spallation Neutron Source (SNS) Project

    Ciovati, G.; Kneisel, P.; Brawley, J.; Bundy, R.; Campisi, I.; Davis, K.; Macha, K.; Machie, D.; Mammosser, J.; Morgan, S.; Sundelin, R.; Turlington, L.; Wilson, K.; Doleans, M.; Kim, S.H.; Barni, D.; Pagani, C.; Pierini, P.; Matsumoto, K.; Mitchell, R.; Schrage, D.; Parodi, R.; Sekutowicz, J.; Ylae-Oijala, P.

    2001-01-01

    The Spallation Neutron Source project includes a superconducting linac section in the energy range from 192 MeV to 1000 MeV, operating at a frequency of 805 MHz at 2.1 K. For this energy range two types of cavities are needed with geometrical beta - values of beta= 0.61 and beta= 0.81. An aggressive cavity prototyping program is being pursued at Jlab, which calls for fabricating and testing of four beta= 0.61 cavities and two beta= 0.81 cavities. Both types consist of six cells made from high purity niobium and feature one HOM coupler on each beam pipe and a port for a high power coaxial input coupler. Three of the four beta= 0.61 cavities will be used for a cryomodule test in early 2002. At this time four medium beta cavities and one high beta cavity have been completed at JLab. The first tests on the beta=0.61 cavity and the beta= 0.81 exceeded the design values for gradient and Q - value: E acc = 1 0.3 MV/m and Q = 5 x 10 9 at 2.1K for beta= 0.61 and E acc = 12.3 MV/m and Q = 5 x 10 9 at 2.1K for beta= 0.81. One of the medium beta cavities has been equipped with an integrated helium vessel and measurements of the static and dynamic Lorentz force detuning will be done and compared to the ''bare'' cavities. In addition two single cell cavities have been fabricated, equipped with welded-on HOM couplers. They are being used to evaluate the HOM couplers with respect to multipacting, fundamental mode rejection and HOM damping as far as possible in a single cell. This paper will describe the cavity design with respect to electrical and mechanical features, the fabrication efforts and the results obtained with the different cavities existing at the time of this workshop

  20. Niobium coaxial quarter-wave cavities for the New Delhi booster linac

    Shepard, K.W.; Roy, A.; Potukuchi, P.N.

    1993-01-01

    This paper reports the design and construction status of a prototype superconducting niobium accelerating structure consisting of a pair of quarter-wave coaxial-line cavities which are strongly coupled with a superconducting loop. Quarter-wave resonators are two-gap accelerating structures and are relatively short, so that a large number of independently-phased cavities is required for a linac. Strongly coupling several cavities can reduce the number of independently-phased elements, but at the cost of reducing the range of useful velocity acceptance for each element. Coupling two cavities splits the accelerating rf eigenmode into two resonant modes each of which covers a portion of the full velocity acceptance range of the original single cavity mode. Using both of these resonant modes makes feasible the use of coupled cavity pairs for a linac with little loss m velocity acceptance. Design details for the niobium cavity pair and the results of preliminary tests of multipacting behavior are discussed

  1. Resonator modes and mode dynamics for an external cavity-coupled laser array

    Nair, Niketh; Bochove, Erik J.; Aceves, Alejandro B.; Zunoubi, Mohammad R.; Braiman, Yehuda

    2015-03-01

    Employing a Fox-Li approach, we derived the cold-cavity mode structure and a coupled mode theory for a phased array of N single-transverse-mode active waveguides with feedback from an external cavity. We applied the analysis to a system with arbitrary laser lengths, external cavity design and coupling strengths to the external cavity. The entire system was treated as a single resonator. The effect of the external cavity was modeled by a set of boundary conditions expressed by an N-by-N frequency-dependent matrix relation between incident and reflected fields at the interface with the external cavity. The coupled mode theory can be adapted to various types of gain media and internal and external cavity designs.

  2. Niobium coaxial quarter-wave cavities for the New Delhi booster linac

    Shepard, K.W. [Argonne National Lab., IL (United States); Roy, A.; Potukuchi, P.N. [Nuclear Science Centre, New Delhi (India)

    1993-07-01

    This paper reports the design and construction status of a prototype superconducting niobium accelerating structure consisting of a pair of quarter-wave coaxial-line cavities which are strongly coupled with a superconducting loop. Quarter-wave resonators are two-gap accelerating structures and are relatively short, so that a large number of independently-phased cavities is required for a linac. Strongly coupling several cavities can reduce the number of independently-phased elements, but at the cost of reducing the range of useful velocity acceptance for each element. Coupling two cavities splits the accelerating rf eigenmode into two resonant modes each of which covers a portion of the full velocity acceptance range of the original single cavity mode. Using both of these resonant modes makes feasible the use of coupled cavity pairs for a linac with little loss m velocity acceptance. Design details for the niobium cavity pair and the results of preliminary tests of multipacting behavior are discussed.

  3. Lithographic wavelength control of an external cavity laser with a silicon photonic crystal cavity-based resonant reflector.

    Liles, Alexandros A; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of a new design for external cavity hybrid lasers consisting of a III-V semiconductor optical amplifier (SOA) with fiber reflector and a photonic crystal (PhC)-based resonant reflector on SOI. The silicon reflector is composed of an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB.

  4. Cavity temperature and flow characteristics in a gas-core test reactor

    Putre, H. A.

    1973-01-01

    A test reactor concept for conducting basic studies on a fissioning uranium plasma and for testing various gas-core reactor concepts is analyzed. The test reactor consists of a conventional fuel-element region surrounding a 61-cm-(2-ft-) diameter cavity region which contains the plasma experiment. The fuel elements provide the neutron flux for the cavity region. The design operating conditions include 60-MW reactor power, 2.7-MW cavity power, 200-atm cavity pressure, and an average uranium plasma temperature of 15,000 K. The analytical results are given for cavity radiant heat transfer, hydrogen transpiration cooling, and uranium wire or powder injection.

  5. RF Behavior of Cylindrical Cavity Based 240 GHz, 1 MW Gyrotron for Future Tokamak System

    Kumar, Nitin; Singh, Udaybir; Bera, Anirban; Sinha, A. K.

    2017-11-01

    In this paper, we present the RF behavior of conventional cylindrical interaction cavity for 240 GHz, 1 MW gyrotron for futuristic plasma fusion reactors. Very high-order TE mode is searched for this gyrotron to minimize the Ohmic wall loading at the interaction cavity. The mode selection process is carried out rigorously to analyze the mode competition and design feasibility. The cold cavity analysis and beam-wave interaction computation are carried out to finalize the cavity design. The detail parametric analyses for interaction cavity are performed in terms of mode stability, interaction efficiency and frequency. In addition, the design of triode type magnetron injection gun is also discussed. The electron beam parameters such as velocity ratio and velocity spread are optimized as per the requirement at interaction cavity. The design studies presented here confirm the realization of CW, 1 MW power at 240 GHz frequency at TE46,17 mode.

  6. Frequency-feedback cavity enhanced spectrometer

    Hovde, David Christian; Gomez, Anthony

    2015-08-18

    A spectrometer comprising an optical cavity, a light source capable of producing light at one or more wavelengths transmitted by the cavity and with the light directed at the cavity, a detector and optics positioned to collect light transmitted by the cavity, feedback electronics causing oscillation of amplitude of the optical signal on the detector at a frequency that depends on cavity losses, and a sensor measuring the oscillation frequency to determine the cavity losses.

  7. Superconducting cavities for the APT accelerator

    Krawczyk, F.L.; Gentzlinger, R.C.; Haynes, B.; Montoya, D.I.; Rusnak, B.; Shapiro, A.H.

    1997-01-01

    The design of an Accelerator Production of Tritium (APT) facility being investigated at Los Alamos includes a linear accelerator using superconducting rf-cavities for the acceleration of a high-current cw proton beam. For electron accelerators with particles moving at the speed of light (β ∼ 1.0), resonators with a rounded shape, consisting of ellipsoidal and cylindrical sections, are well established. They are referred to as elliptical cavities. For the APT-design, this shape has been adapted for much slower proton beams with β ranging from 0.60 to 0.94. This is a new energy range, in which resonators of an elliptical type have never been used before. Simulations with the well-proven electromagnetic modeling tools MAFIA and SUPERFISH were performed. The structures have been optimized for their rf and mechanical properties as well as for beam dynamics requirements. The TRAK-RF simulation code is used to investigate potential multipacting in these structures. All the simulations will be put to a final test in experiments performed on single cell cavities that have started in the structures laboratory

  8. Nonlocal Intracranial Cavity Extraction

    Manjón, José V.; Eskildsen, Simon F.; Coupé, Pierrick; Romero, José E.; Collins, D. Louis; Robles, Montserrat

    2014-01-01

    Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV) is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden. PMID:25328511

  9. Nonlocal Intracranial Cavity Extraction

    José V. Manjón

    2014-01-01

    Full Text Available Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden.

  10. CavityPlus: a web server for protein cavity detection with pharmacophore modelling, allosteric site identification and covalent ligand binding ability prediction.

    Xu, Youjun; Wang, Shiwei; Hu, Qiwan; Gao, Shuaishi; Ma, Xiaomin; Zhang, Weilin; Shen, Yihang; Chen, Fangjin; Lai, Luhua; Pei, Jianfeng

    2018-05-10

    CavityPlus is a web server that offers protein cavity detection and various functional analyses. Using protein three-dimensional structural information as the input, CavityPlus applies CAVITY to detect potential binding sites on the surface of a given protein structure and rank them based on ligandability and druggability scores. These potential binding sites can be further analysed using three submodules, CavPharmer, CorrSite, and CovCys. CavPharmer uses a receptor-based pharmacophore modelling program, Pocket, to automatically extract pharmacophore features within cavities. CorrSite identifies potential allosteric ligand-binding sites based on motion correlation analyses between cavities. CovCys automatically detects druggable cysteine residues, which is especially useful to identify novel binding sites for designing covalent allosteric ligands. Overall, CavityPlus provides an integrated platform for analysing comprehensive properties of protein binding cavities. Such analyses are useful for many aspects of drug design and discovery, including target selection and identification, virtual screening, de novo drug design, and allosteric and covalent-binding drug design. The CavityPlus web server is freely available at http://repharma.pku.edu.cn/cavityplus or http://www.pkumdl.cn/cavityplus.

  11. A Study on the Flow Characterization in the Reactor Cavity

    Lee, Ho Jung; Ko, Kwang Jeok; Kim, Sung Hwan; Kim, Min Gyu; Cho, Yeon Ho; Kim, Hyun Min [KEPCO Engineering and Construction Co. Ltd., Deajeon (Korea, Republic of)

    2016-10-15

    In this study, the flow characterization of the cooling air in reactor cavity nearby RCPSA has been analyzed by using a 3 dimensional model and the ANSYS CFX software in order to predict the Convective Heat Transfer Coefficient (CHTC) of the RCPSA. The Reactor Cavity is the annular space by the concrete structure, the Reactor Cavity Pool Seal Assembly (RCPSA), which consists of the welded steel and is designed to be installed between the RV and the refueling pool floor, and the Reactor Vessel (RV). For such reason, the RCPSA should be designed to provide the cooling air passage for ventilation to circulate high temperature air passing by the RV during the reactor operation. It means that the RCPSA is influenced by the convection of cooling air and the thermal expansion of the RV. Therefore, the flow characterization at the reactor cavity is one of the factors of the RCPSA design during the reactor operation. The flow distribution of the cooling air in reactor cavity nearby RCPSA has been analyzed using ANSYS CFX software to obtain the CHTC at surface of the RCPSA. 1) The temperature from the RV and the insulation is one of the critical factors for the thermal gradient of the cooling air and the CHTC in the reactor cavity. 2) The rapid change of the CHTC in inner region nearby inner and outer flexure is related to the geometry shape of the RCPSA and velocity of cooling air.

  12. Prototype rf cavity for the HISTRAP accelerator

    Mosko, S.W.; Dowling, D.T.; Olsen, D.K.

    1989-01-01

    HISTRAP, a proposed synchrotron-cooling-storage ring designed to both accelerate and decelerate very highly charged very heavy ions for atomic physics research, requires an rf accelerating system to provide /+-/2.5 kV of peak accelerating voltage per turn while tuning through a 13.5:1 frequency range in a fraction of a second. A prototype half-wave, single gap rf cavity with biased ferrite tuning was built and tested over a continuous tuning range of 200 kHz through 2.7 MHz. Initial test results establish the feasibility of using ferrite tuning at the required rf power levels. The resonant system is located entirely outside of the accelerator's 15cm ID beam line vacuum enclosure except for a single rf window which serves as an accelerating gap. Physical separation of the cavity and the beam line permits in situ vacuum baking of the beam line at 300/degree/C

  13. Modeling of Coupled Nano-Cavity Lasers

    Skovgård, Troels Suhr

    -of-states and it is argued that Purcell enhancement should also be included in stimulated recombination term, contrary to the common practice in the literature. It is shown that for quantum well devices, the Purcell enhancement is effectively independent of the cavity quality factor due to the broad electronic density......-of-states relative to the optical density-of-states. The low effective Purcell eect for quantum well devices limits the highest possible modulation bandwidth to a few tens of gigahertz, which is comparable to the performance of conventional diode lasers. Compared to quantum well devices, quantum dot devices have...... is useful for design of coupled systems. A tight-binding description for coupled nanocavity lasers is developed and employed to investigate the phase-locking behavior for the system of two coupled cavities. Phase-locking is found to be critically dependent on exact parameter values and to be dicult...

  14. Signal attenuation due to cavity leakage

    Sherman, M.H.; Modera, M.P.

    1988-01-01

    The propagation of sound waves in fluids requires information about three properties of the system: capacitance (compressibility), resistance (friction), and inductance (inertia). Acoustical design techniques to date have tended to ignore the frictional effects associated with airflow across the envelope of the acoustic cavity (e.g., resistive vents). Since such leakage through the cavity envelope is best expressed with a power law dependence on the pressure, standard Fourier techniques that rely on linearity cannot be used. In this article, the theory relevant to nonlinear leakage is developed and equations presented. Potential applications of the theory to techniques for quantifying the leakage of buildings are presented. Experimental results from pressure decays in a full-scale test structure are presented and the leakage so measured is compared with independent measurements to demonstrate the technique

  15. Optimizing SRF Gun Cavity Profiles in a Genetic Algorithm Framework

    Hofler, Alicia; Evtushenko, Pavel; Marhauser, Frank

    2009-01-01

    Automation of DC photoinjector designs using a genetic algorithm (GA) based optimization is an accepted practice in accelerator physics. Allowing the gun cavity field profile shape to be varied can extend the utility of this optimization methodology to superconducting and normal conducting radio frequency (SRF/RF) gun based injectors. Finding optimal field and cavity geometry configurations can provide guidance for cavity design choices and verify existing designs. We have considered two approaches for varying the electric field profile. The first is to determine the optimal field profile shape that should be used independent of the cavity geometry, and the other is to vary the geometry of the gun cavity structure to produce an optimal field profile. The first method can provide a theoretical optimal and can illuminate where possible gains can be made in field shaping. The second method can produce more realistically achievable designs that can be compared to existing designs. In this paper, we discuss the design and implementation for these two methods for generating field profiles for SRF/RF guns in a GA based injector optimization scheme and provide preliminary results.

  16. Compact 400-Mhz Half-Wave Spoke Resonator Crab Cavity for the LHC Update

    Li, Zenghai

    2010-01-01

    Crab cavities are proposed for the LHC upgrade to improve the luminosity. There are two possible crab cavity installations for the LHC upgrade: the global scheme at Interaction Region (IR) 4 where the beam-beam separation is about 420-mm, and the local scheme at the IR5 where the beam-beam separation is only 194-mm. One of the design requirements as the result of a recent LHC-Crab cavity workshop is to develop a 400-MHz cavity design that can be utilized for either the global or local schemes at IR4 or IR5. Such a design would offer more flexibility for the final upgrade installation, as the final crabbing scheme is yet to be determined, and save R and D cost. The cavity size of such a design, however, is limited by the beam-beam separation at IR5 which can only accommodate a cavity with a horizontal size of about 145-mm, which is a design challenge for a 400-MHz cavity. To meet the new design requirements, we have developed a compact 400-MHz half-wave spoke resonator (HWSR) crab cavity that can fit into the tight spaces available at either IR4 or IR5. In this paper, we present the optimization of the HWSR cavity shape and the design of HOM, LOM, and SOM couplers for wakefield damping.

  17. Photons in a spherical cavity

    Ionescu-Pallas, N.; Vlad, V.I.

    1999-01-01

    The spectrum of black body radiation at the absolute temperature T, in an ideal spherical cavity of radius R, is studied. The departures from the classical predictions of Planck's theory, due to the discrete energies of the radiation quanta confined inside the cavity, depend on the adiabatic invariant RT and are significant for RT≤ 1 cm K. Special attention was paid to evidence sudden changes in the spectrum intensities, forbidden bands of frequency, as well as major modifications of the total energy for RT≤ 1 cm K. Similar effects were present in case of a cubic cavity too. (authors)

  18. Recent Developments in SRF Cavity Science and Performance

    G. Ciovati

    2006-08-10

    The performances of SRF cavities made of high purity bulk niobium have been improving in the last few years and surface magnetic fields (Bp) close to the thermodynamic critical field of niobium have been achieved in a few cases. The recommendation made in 2004 in favor of SRF as the technology of choice for the International Linear Collider (ILC), requires improving the reliability of multi-cell cavities operating at accelerating gradients (Eacc) of the order of 35 MV/m. Additionally, a better understanding of the present limitations to cavity performance, such as the high-field Q-drop is needed. This contribution presents some recent developments in SRF cavity science and performance. Among the most significant advances of the last few years, new cavity shapes with lower ratio Bp/Eacc were designed and tested. Cavities made of large-grain niobium became available, promising lower cost at comparable performance to standard fine-grain ones and several tests on single-cell cavities were done to gain a better understanding of high-field losses. In addition, studies to improve the reliability of electropolishing are being carried out by several research groups.

  19. Perpendicular biased ferrite tuned RF cavity for the TRIUMF KAON Factory booster ring

    Poirier, R.L.; Enegren, T.; Haddock, C.

    1989-03-01

    The rf cavity for the booster ring requires a frequency swing of 46 MHz to 62 MHz at a repetition rate of 50 Hz. The possibility of using the LANL booster cavity design with a yttrium garnet ferrite tuner biased perpendicular to the rf field, in the longitudinal direction, is being investigated. In order to minimize the stray magnetic biasing field on the beam axis, an alternative scheme similar to the design being proposed for the LANL main ring cavity in which the ferrite is perpendicular biased in the radial direction, is being considered. The behaviour of the rf cavity and the magnetizing circuit for both designs are discussed

  20. A diode-pumped Tm:YAG laser with an elliptical cavity mode

    Lipnicki, E.; Dawes, J.M.; Browne, P.G.

    2000-01-01

    Full text: A cavity consisting of cylindrical mirrors/lenses resulting in an elliptical cavity mode is being applied to a 3-level laser; Tm:YAG which lases near 2μm. This arrangement allows the use of simple pump beam optics but also ensures efficient mode matching with good output beam quality. This cavity has been designed and modelled with experiments under way to explore the advantages of this laser design

  1. Cavity and goaf control

    Stassen, P

    1978-01-01

    A summary of stowing, including a definition, calculation of stowing material requirements and settling of packs is given. A) Stowing using dirt found locally - the dirt bands in the seam - the use of ripping dirt brought down by the scraper loader and used for packing purposes and the construction of dummy roads. B) Control of cavities by leaving short, thick props and timber chocks in place. C) Stowing methods involving imported firt: packing by hand, use of scraper loaders, slinger stowing and control led-gravity stowing. D) Pneumatic stowing: describes the various types of machine and their scope; pipelines, their installation and cost price; pneumatic stowing in conjunc tion with powered supports; the use of crusher-stowers for stowing ripping dirt; construction of anhydrite packs by means of a pneumatic stower. E) Hydraulic stowing: how it works, the materials involved, utilization conditions, the surface storage post, pipes, stoppings with stowed material, water removal, rates of hydraulic stowing, results of theoretical studies, and the use of hydraulic stowing in the metal-mines. F) Pumped packs: how they work, how the packs are installed, the strength of the packs and their various uses. G) Caving: describes the principle of caving, support patterns, caving with packs and makes a comparison between caving and stowing. H) Comparison between the various methods of stowing compares pneumatic with hydraulic stowing methods; compares packing by hand and mechanical stowing compares surface subsidence in terms of the method of goaf used underground. An appendix gives details of equipment used. (15 refs.) (In French)

  2. Loggerhead oral cavity morphometry study

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard external morphometrics and internal oral cavity morphometrics data were collected on wild and captive reared loggerhead sea turtles in size classes ranging...

  3. Niobium LEP 2 accelerating cavities

    An accelerating cavity from LEP. This could be cut open to show the layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities were used in an upgrade of the LEP accelerator to double the energy of the particle beams.

  4. Bistability of Cavity Magnon Polaritons

    Wang, Yi-Pu; Zhang, Guo-Qiang; Zhang, Dengke; Li, Tie-Fu; Hu, C.-M.; You, J. Q.

    2018-01-01

    We report the first observation of the magnon-polariton bistability in a cavity magnonics system consisting of cavity photons strongly interacting with the magnons in a small yttrium iron garnet (YIG) sphere. The bistable behaviors emerged as sharp frequency switchings of the cavity magnon polaritons (CMPs) and related to the transition between states with large and small numbers of polaritons. In our experiment, we align, respectively, the [100] and [110] crystallographic axes of the YIG sphere parallel to the static magnetic field and find very different bistable behaviors (e.g., clockwise and counter-clockwise hysteresis loops) in these two cases. The experimental results are well fitted and explained as being due to the Kerr nonlinearity with either a positive or negative coefficient. Moreover, when the magnetic field is tuned away from the anticrossing point of CMPs, we observe simultaneous bistability of both magnons and cavity photons by applying a drive field on the lower branch.

  5. SRF Cavity Fabrication and Materials

    Singer, W

    2014-07-17

    The technological and metallurgical requirements of material for highgradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10μg/g. The hydrogen content should be kept below 2μg/g to prevent degradation of the Q-value under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Defects may be detected by quality control methods such as eddy current scanning and identified by a number of special methods. Conventional and alternative cavity fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and Electron-Beam Welding (EBW). The welding of half-cells is a delicate...

  6. HOM/LOM Coupler Study for the ILC Crab Cavity

    Xiao, L.; Li, Z.; Ko, K.

    2007-01-01

    The FNAL 9-cell 3.9GHz deflecting mode cavity designed for the CKM experiment was chosen as the baseline design for the ILC BDS crab cavity. The full 9-cell CKM cavity including the coupler end-groups was simulated using the parallel eigensolver Omega3P and scattering parameter solver S3P. It was found that both the notch filters for the HOM/LOM couplers are very sensitive to the notch gap, which is about 1.6MHz/micron and is more than 10 times more sensitive than the TTF cavity. It was also found in the simulation that the unwanted vertical π-mode (SOM) is strongly coupled to the horizontal 7π/9 mode which causes x-y coupling and reduces the effectiveness of the SOM damping. To meet the ILC requirements, the HOM/LOM couplers are redesigned to address these issues. With the new designs, the damping of the HOM/LOM modes is improved. The sensitivity of the notch filter for the HOM coupler is reduced by one order of magnitude. The notch filter for the LOM coupler is eliminated in the new design which significantly simplifies the geometry. In this paper, we will present the simulation results of the original CKM cavity and the progresses on the HOM/LOM coupler re-design and optimization

  7. ANT tuner retrofit for LEB cavity

    Walling, L.; Goren, Y.; Kwiatkowski, S.

    1994-03-01

    This report describes a ferrite tuner design for the LEB cavity that utilizes techniques for bonding ferrite to metallic cooling plates that is utilized in the high-power rf and microwave industry. A test tuner was designed to fit into the existing LEB-built magnet and onto the Grimm LEB Cavity. It will require a new vacuum window in order to attain maximal tuning range and high voltage capability and a new center conductor of longer length and a different vacuum window connection than the Grimm center conductor. However, the new center conductor will be essentially identical to the Grimm center conductor in its basic construction and in the way it connects to the stand for support. The tuner is mechanically very similar to high-power stacked circulators built by ANT of Germany and was designed according to ANT's established engineering and design criteria and SSC LEB tuning and power requirements. The tuner design incorporates thin tiles of ferrite glued using a high-radiation-resistance epoxy to copper-plated stainless steel cooling plates of thickness 6.5 mm with water cooling channels inside the plates. The cooling plates constitute 16 pie-shaped segments arranged in a disk. They are electrically isolated from each other to suppress eddy currents. Five of these disks are arranged in parallel with high-pressure rf contacts between the plates at the outer radius. The end walls are slotted copper-plated stainless steel of thickness 3 mm

  8. LEP Radio Frequency Copper Cavity

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  9. Demountable damped cavity for HOM-damping in ILC superconducting accelerating cavities

    Konomi, T., E-mail: konomi@ims.ac.jp [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yasuda, F. [University of Tokyo, Bunkyo-ku, Tokyo 113-8654 (Japan); Furuta, F. [Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, NY 14853 (United States); Saito, K. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2014-01-11

    We have designed a new higher-order-mode (HOM) damper called a demountable damped cavity (DDC) as part of the R and D efforts for the superconducting cavity of the International Linear Collider (ILC). The DDC has two design concepts. The first is an axially symmetrical layout to obtain high damping efficiency. The DDC has a coaxial structure along the beam axis to realize strong coupling with HOMs. HOMs are damped by an RF absorber at the end of the coaxial waveguide and the accelerating mode is reflected by a choke filter mounted at the entrance of the coaxial waveguide. The second design concept is a demountable structure to facilitate cleaning, in order to suppress the Q-slope problem in a high field. A single-cell cavity with the DDC was fabricated to test four performance parameters. The first was frequency matching between the accelerating cavity and the choke filter. Since the bandwidth of the resonance frequency in a superconducting cavity is very narrow, there is a possibility that the accelerating field will leak to the RF absorber because of thermal shrinkage. The design bandwidth of the choke filter is 25 kHz. It was demonstrated that frequency matching adjusted at room temperature could be successfully maintained at 2 K. The second parameter was the performance of the demountable structure. At the joint, the magnetic field is 1/6 of the maximum field in the accelerating cavity. Ultimately, the accelerating field reached 19 MV/m and Q{sub 0} was 1.5×10{sup 10} with a knife-edge shape. The third parameter was field emission and multipacting. Although the choke structure has numerous parallel surfaces that are susceptible to the multipacting problem, it was found that neither field emission nor multipacting presented problems in both an experiment and simulation. The final parameter was the Q values of the HOM. The RF absorber adopted in the system is a Ni–Zn ferrite type. The RF absorber shape was designed based on the measurement data of permittivity

  10. Demountable damped cavity for HOM-damping in ILC superconducting accelerating cavities

    Konomi, T.; Yasuda, F.; Furuta, F.; Saito, K.

    2014-01-01

    We have designed a new higher-order-mode (HOM) damper called a demountable damped cavity (DDC) as part of the R and D efforts for the superconducting cavity of the International Linear Collider (ILC). The DDC has two design concepts. The first is an axially symmetrical layout to obtain high damping efficiency. The DDC has a coaxial structure along the beam axis to realize strong coupling with HOMs. HOMs are damped by an RF absorber at the end of the coaxial waveguide and the accelerating mode is reflected by a choke filter mounted at the entrance of the coaxial waveguide. The second design concept is a demountable structure to facilitate cleaning, in order to suppress the Q-slope problem in a high field. A single-cell cavity with the DDC was fabricated to test four performance parameters. The first was frequency matching between the accelerating cavity and the choke filter. Since the bandwidth of the resonance frequency in a superconducting cavity is very narrow, there is a possibility that the accelerating field will leak to the RF absorber because of thermal shrinkage. The design bandwidth of the choke filter is 25 kHz. It was demonstrated that frequency matching adjusted at room temperature could be successfully maintained at 2 K. The second parameter was the performance of the demountable structure. At the joint, the magnetic field is 1/6 of the maximum field in the accelerating cavity. Ultimately, the accelerating field reached 19 MV/m and Q 0 was 1.5×10 10 with a knife-edge shape. The third parameter was field emission and multipacting. Although the choke structure has numerous parallel surfaces that are susceptible to the multipacting problem, it was found that neither field emission nor multipacting presented problems in both an experiment and simulation. The final parameter was the Q values of the HOM. The RF absorber adopted in the system is a Ni–Zn ferrite type. The RF absorber shape was designed based on the measurement data of permittivity and

  11. Experimental study of pulsed heating of electromagnetic cavities

    Pritzkau, D.P.; Menegat, A.; Siemann, R.H.

    1997-01-01

    An experiment to study the effects of pulsed heating in electromagnetic cavities will be performed. Pulsed heating is believed to be the limiting mechanism of high acceleration gradients at short wavelengths. A cylindrical cavity operated in the TE 011 mode at a frequency of 11.424 GHz will be used. A klystron will be used to supply a peak input power of 20 MW with a pulse length of 1.5 μs. The temperature response of the cavity will be measured by a second waveguide designed to excite a TE 012 mode in the cavity with a low-power CW signal at a frequency of 17.8 GHz. The relevant theory of pulsed heating will be discussed and the results from cold-testing the structure will be presented

  12. Magnetic field mapping for HIE-ISOLDE cavities

    Bianchi, Antonio

    2015-01-01

    In this report the importance of a magnetic field mapping (B-mapping) around the HIE-ISOLDE superconducting cavities is described. In fact the cavities are not always above the HIE-ISOLDE specification, so it is important to understand the reason of their bad performances and improve them. For doing the B-mapping, the supports for three fluxgate sensors are designed and manufactured. The material of the supports is PEEK: a proper thermoplastic for the extreme operation conditions of the cavities. According to simulation of behavior of external magnetic field, an initial configuration of the sensors is proposed for the first measurements, in order to get the extent of Meissner effect around the superconducting cavities.

  13. Reducing the asymmetry in coupled cavity of linear accelerator

    Wei Xianlin; Wu Congfeng

    2013-01-01

    Background: With the development of high energy physics, high performance of electron linear accelerator is required for large collider, FEL and high brightness synchrotron radiation light source. Structure asymmetry of single coupler destroys the symmetry of field distribution in coupled cavity, which reduces the quality of beam. Purpose: Optimize the asymmetry of field distribution in coupled cavity and improve the quality of beam. Methods: The simulation designs are made for single offset coupler, double symmetry coupler and the new coupler loaded by dielectric rods at X band by using CST microwave studio code. Results: The results show that the distribution of field in coupled cavity is better and all particles almost locate at the center of beam hole after beam passing through the coupler loaded by dielectric rods. The energy spread has also been significantly improved. Conclusions: The coupler loaded by dielectric rods can optimize the asymmetry of field distribution in coupled cavity and improve the quality of beam. (authors)

  14. Observation of the exceptional point in cavity magnon-polaritons.

    Zhang, Dengke; Luo, Xiao-Qing; Wang, Yi-Pu; Li, Tie-Fu; You, J Q

    2017-11-08

    Magnon-polaritons are hybrid light-matter quasiparticles originating from the strong coupling between magnons and photons. They have emerged as a potential candidate for implementing quantum transducers and memories. Owing to the dampings of both photons and magnons, the polaritons have limited lifetimes. However, stationary magnon-polariton states can be reached by a dynamical balance between pumping and losses, so the intrinsically nonequilibrium system may be described by a non-Hermitian Hamiltonian. Here we design a tunable cavity quantum electrodynamics system with a small ferromagnetic sphere in a microwave cavity and engineer the dissipations of photons and magnons to create cavity magnon-polaritons which have non-Hermitian spectral degeneracies. By tuning the magnon-photon coupling strength, we observe the polaritonic coherent perfect absorption and demonstrate the phase transition at the exceptional point. Our experiment offers a novel macroscopic quantum platform to explore the non-Hermitian physics of the cavity magnon-polaritons.

  15. Cavity Heating Experiments Supporting Shuttle Columbia Accident Investigation

    Everhart, Joel L.; Berger, Karen T.; Bey, Kim S.; Merski, N. Ronald; Wood, William A.

    2011-01-01

    The two-color thermographic phosphor method has been used to map the local heating augmentation of scaled idealized cavities at conditions simulating the windward surface of the Shuttle Orbiter Columbia during flight STS-107. Two experiments initiated in support of the Columbia Accident Investigation were conducted in the Langley 20-Inch Mach 6 Tunnel. Generally, the first test series evaluated open (length-to-depth less than 10) rectangular cavity geometries proposed as possible damage scenarios resulting from foam and ice impact during launch at several discrete locations on the vehicle windward surface, though some closed (length-to-depth greater than 13) geometries were briefly examined. The second test series was designed to parametrically evaluate heating augmentation in closed rectangular cavities. The tests were conducted under laminar cavity entry conditions over a range of local boundary layer edge-flow parameters typical of re-entry. Cavity design parameters were developed using laminar computational predictions, while the experimental boundary layer state conditions were inferred from the heating measurements. An analysis of the aeroheating caused by cavities allowed exclusion of non-breeching damage from the possible loss scenarios being considered during the investigation.

  16. Study of superconducting cavities for high power proton accelerators

    Biarrotte, J.L.

    2000-01-01

    The research program on hybrid reactors has started in France in order to study the technologies allowing the transmutation of radioactive wastes thanks to a spallation neutron source supplied by a linear high intensity proton accelerator. The study of the high energy part of this accelerator (superconducting accelerator for hybrid) has started, and its aim is the design of superconducting radiofrequency cavities which make the two different sections of the accelerator (0.47 and 0.65). This thesis presents the advance of the work carried out on this topic since 1997, in particular the design and optimization of the 5-cell cavities which work at the 704.4 MHz frequency. The experimental part of the study has been carried out in parallel with the industrial fabrication (Cerca) of several prototypes of mono-cell cavities. These cavities have shown very good RF performances during the tests in vertical cryostat; the A 102 A cavity, in particular develops a Q0 of 7.10 10 (indicating very low RF losses) and reaches an accelerator field of 25 MV/m, i.e. more than two times the specified value (about 10 MV/V). Finally, a new risk analysis method for the excitation of the upper modes is proposed. This method shows in particular the uselessness of the implementation of HOM couplers on the cavities for a continuous beam use. (J.S.)

  17. Evaluation of a new method of RF power coupling to acceleration cavity of charged particles accelerators

    A M Poursaleh

    2017-08-01

    Full Text Available In this paper, the feasibility studty of a new method of RF power coupling to acceleration cavity of charged particles accelerator will be evaluated. In this method a slit is created around the accelerator cavity, and RF power amplifier modules is connected directly to the acceleration cavity. In fact, in this design, the cavity in addition to acting as an acceleration cavity, acts as a RF power combiner. The benefits of this method are avoiding the use of RF vacuum tubes, transmission lines, high power combiner and coupler. In this research, cylindrical and coaxial cavities were studied, and a small sample coaxial cavity is build by this method. The results of the resarch showed that compact, economical and safe RF accelerators can be achieved by the proposed method

  18. Qualification of niobium materials for superconducting radio frequency cavity applications: View of a condensed matter physicist

    Roy, S. B.; Myneni, G. R.

    2015-12-01

    We address the issue of qualifications of the niobium materials to be used for superconducting radio frequency (SCRF) cavity fabrications, from the point of view of a condensed matter physicist/materials scientist. We focus on the particular materials properties of niobium required for the functioning a SCRF cavity, and how to optimize the same properties for the best SCRF cavity performance in a reproducible manner. In this way the niobium materials will not necessarily be characterized by their purity alone, but in terms of those materials properties, which will define the limit of the SCRF cavity performance and also other related material properties, which will help to sustain this best SCRF cavity performance. Furthermore we point out the need of standardization of the post fabrication processing of the niobium-SCRF cavities, which does not impair the optimized superconducting and thermal properties of the starting niobium-materials required for the reproducible performance of the SCRF cavities according to the design values.

  19. Qualification of niobium materials for superconducting radio frequency cavity applications: View of a condensed matter physicist

    Roy, S. B., E-mail: sbroy@rrcat.gov.in [Magnetic & Superconducting Materials Section, Materials & Advanced Accelerator Sciences Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Myneni, G. R., E-mail: rao@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, Virginia (United States)

    2015-12-04

    We address the issue of qualifications of the niobium materials to be used for superconducting radio frequency (SCRF) cavity fabrications, from the point of view of a condensed matter physicist/materials scientist. We focus on the particular materials properties of niobium required for the functioning a SCRF cavity, and how to optimize the same properties for the best SCRF cavity performance in a reproducible manner. In this way the niobium materials will not necessarily be characterized by their purity alone, but in terms of those materials properties, which will define the limit of the SCRF cavity performance and also other related material properties, which will help to sustain this best SCRF cavity performance. Furthermore we point out the need of standardization of the post fabrication processing of the niobium-SCRF cavities, which does not impair the optimized superconducting and thermal properties of the starting niobium-materials required for the reproducible performance of the SCRF cavities according to the design values.

  20. Qualification of niobium materials for superconducting radio frequency cavity applications: View of a condensed matter physicist

    Roy, S. B.; Myneni, G. R.

    2015-01-01

    We address the issue of qualifications of the niobium materials to be used for superconducting radio frequency (SCRF) cavity fabrications, from the point of view of a condensed matter physicist/materials scientist. We focus on the particular materials properties of niobium required for the functioning a SCRF cavity, and how to optimize the same properties for the best SCRF cavity performance in a reproducible manner. In this way the niobium materials will not necessarily be characterized by their purity alone, but in terms of those materials properties, which will define the limit of the SCRF cavity performance and also other related material properties, which will help to sustain this best SCRF cavity performance. Furthermore we point out the need of standardization of the post fabrication processing of the niobium-SCRF cavities, which does not impair the optimized superconducting and thermal properties of the starting niobium-materials required for the reproducible performance of the SCRF cavities according to the design values

  1. Thermal modeling of a pressurized air cavity receiver for solar dish Stirling system

    Zou, Chongzhe; Zhang, Yanping; Falcoz, Quentin; Neveu, Pierre; Li, Jianlan; Zhang, Cheng

    2017-06-01

    A solar cavity receiver model for the dish collector system is designed in response to growing demand of renewable energy. In the present research field, no investigations into the geometric parameters of a cavity receiver have been performed. The cylindrical receiver in this study is composed of an enclosed bottom at the back, an aperture at the front, a helical pipe inside the cavity and an insulation layer on the external surface of the cavity. The influence of several critical receiver parameters on the thermal efficiency is analyzed in this paper: cavity inner diameter and cavity length. The thermal model in this paper is solved considering the cavity dimensions as variables. Implementing the model into EES, each parameter influence is separately investigated, and a preliminary optimization method is proposed.

  2. State of the art of multicell SC cavities and perspectives

    Peter Kneisel

    2002-01-01

    Superconducting cavity technology has made major progresses in the last decade with the introduction of high purity niobium on an industrial scale and, at the same time, by an improved understanding of the limiting processes in cavity performance, such as multipacting, field emission loading and thermal break-down. Multicell niobium cavities for beta = 1 particle acceleration, e.g. for the TESLA project, are routinely exceeding gradients of Eacc = 20 MV/m after the application of surface preparation techniques such as buffered chemical polishing or electropolishing, high pressure ultrapure water rinsing, UHV heat treatment and clean room assembly. The successes of the technology for beta = 1 accelerators has triggered a whole set of possible future applications for beta < 1 particle acceleration such as spallation neutron sources (SNS, ESS), transmutation of nuclear waste (TRASCO, ASH) or rare isotopes (RIA). The most advanced of these projects is SNS now under construction at Oak Ridge National Laboratory. This paper will review the technical solutions adopted to advance SRF technology and their impact on cavity performance, based on the SNS prototyping efforts. 2K at these high gradients are no longer out of reach. For the accelerator builder the challenge remains to come up with a good and reasonable design, which takes into account the status of the technology and does not over-estimate the achievable cavity performances in a large assembly such as, e.g., a multi-cavity cryo-module. In the following the criteria for multi-cell sc cavity design are reviewed and it is attempted to give a snapshot of the present status of multi-cell cavity performances

  3. Continuous-wave cavity ringdown spectroscopy based on the control of cavity reflection.

    Li, Zhixin; Ma, Weiguang; Fu, Xiaofang; Tan, Wei; Zhao, Gang; Dong, Lei; Zhang, Lei; Yin, Wangbao; Jia, Suotang

    2013-07-29

    A new type of continuous-wave cavity ringdown spectrometer based on the control of cavity reflection for trace gas detection was designed and evaluated. The technique separated the acquisitions of the ringdown event and the trigger signal to optical switch by detecting the cavity reflection and transmission, respectively. A detailed description of the time sequence of the measurement process was presented. In order to avoid the wrong extraction of ringdown time encountered accidentally in fitting procedure, the laser frequency and cavity length were scanned synchronously. Based on the statistical analysis of measured ringdown times, the frequency normalized minimum detectable absorption in the reflection control mode was 1.7 × 10(-9)cm(-1)Hz(-1/2), which was 5.4 times smaller than that in the transmission control mode. However the signal-to-noise ratio of the absorption spectrum was only 3 times improved since the etalon effect existed. Finally, the peak absorption coefficients of the C(2)H(2) transition near 1530.9nm under different pressures showed a good agreement with the theoretical values.

  4. 21 CFR 872.3260 - Cavity varnish.

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cavity varnish. 872.3260 Section 872.3260 Food and... DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is a device that consists of a compound intended to coat a prepared cavity of a tooth before insertion of...

  5. TEM observations of crack tip: cavity interactions

    Horton, J.A.; Ohr, S.M.; Jesser, W.A.

    1981-01-01

    Crack tip-cavity interactions have been studied by performing room temperature deformation experiments in a transmission electron microscope on ion-irradiated type 316 stainless steel with small helium containing cavities. Slip dislocations emitted from a crack tip cut, sheared, and thereby elongated cavities without a volume enlargement. As the crack tip approached, a cavity volume enlargement occurred. Instead of the cavities continuing to enlarge until they touch, the walls between the cavities fractured. Fracture surface dimples do not correlate in size or density with these enlarged cavities

  6. Impact of Lorentz forces on a Spoke cavity with β 0.15 and on a Spiral-2 cavity with β 0.12

    Gassot, H.

    2007-01-01

    Mono-spoke superconducting cavities have been proposed for the acceleration of radioactive ion beams. The interaction of the electromagnetic field with the surface electrical current generates Lorentz forces that operate on the intern wall of the cavity, the distribution of these forces is highly non-linear and varying. The stability of a superconducting cavity is directly linked to the frequency variation due to Lorentz forces and as a consequence the optimized design of a cavity must take into account these forces. In order to optimize the design of a cavity, 3 complementary software have been developed: Catia, a computer-aided-design software, Soprano for electromagnetic modeling and Cast3m for mechanical modeling. Preliminary results show a good agreement between predicted values and experimental data. (A.C.)

  7. Fabrication of elliptical SRF cavities

    Singer, W.

    2017-03-01

    The technological and metallurgical requirements of material for high-gradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10 μg g-1. The hydrogen content should be kept below 2 μg g-1 to prevent degradation of the quality factor (Q-value) under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Traditional and alternative cavity mechanical fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and electron beam welding. The welding of half-cells is a delicate procedure, requiring intermediate cleaning steps and a careful choice of weld parameters to achieve full penetration of the joints. A challenge for a welded construction is the tight mechanical and electrical tolerances. These can be maintained by a combination of mechanical and radio-frequency measurements on half-cells and by careful tracking of weld shrinkage. The main aspects of quality assurance and quality management are mentioned. The experiences of 800 cavities produced for the European XFEL are presented. Another cavity fabrication approach is slicing discs from the ingot and producing cavities by deep drawing and electron beam welding. Accelerating gradients at the level of 35-45 MV m-1 can be achieved by applying electrochemical polishing treatment. The single-crystal option (grain boundary free) is discussed. It seems that in this case, high performance can be achieved by a simplified treatment procedure. Fabrication of the elliptical resonators from a seamless pipe as an alternative is briefly described. This technology has yielded good

  8. Hydroforming of superconducting TESLA cavities

    Singer, W.; Kaiser, H.; Singer, X.

    2003-01-01

    Seamless fabrication of single-cell and multi-cell TESLA shape cavities by hydroforming has been developed at DESY. The forming takes place by expanding the seamless tube with internal water pressure while simultaneously swaging it axially. Tube radius and axial displacement are being computer controlled in accordance with results of FEM simulations and the experimentally obtained strain-stress curve of tube material. Several Nb single cell cavities have been produced. A first bulk Nb double cell cavity has been fabricated. The Nb seamless tubes have been produced by spinning and deep drawing. Surface treatment such as buffered chemical polishing, (BCP), electropolishing (EP), high pressure ultra pure water rinsing (HPR), annealing at 800degC and baking at ca. 150degC have been applied. The best single cell bulk Nb cavity has reached an accelerating gradient of Eacc > 42 MV/m after ca. 250 μm BCP and 100 μm EP. Several bimetallic NbCu single cell cavities of TESLA shape have been fabricated. The seamless tubes have been produced by explosive bonding and subsequent flow forming. The thicknesses of Nb and Cu layers in the tube wall are about 1 mm and 3 mm respectively. The RF performance of NbCu clad cavities is similar to that of bulk Nb cavities. The highest accelerating gradient achieved was 40 MV/m after ca. 180 μm BCP, annealing at 800degC and baking at 140degC for 30 hours. The degradation of the quality factor Qo after repeated quenching is moderate, after ca. 150 quenches it reaches the saturation point of Qo=1.4x10 10 at low field. This indicates that on the basis of RF performance and material costs the combination of hydroforming with tube cladding is a very promising option. (author)

  9. Partial Cavity Flows at High Reynolds Numbers

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2009-11-01

    Partial cavity flows created for friction drag reduction were examined on a large-scale. Partial cavities were investigated at Reynolds numbers up to 120 million, and stable cavities with frictional drag reduction of more than 95% were attained at optimal conditions. The model used was a 3 m wide and 12 m long flat plate with a plenum on the bottom. To create the partial cavity, air was injected at the base of an 18 cm backwards-facing step 2.1 m from the leading edge. The geometry at the cavity closure was varied for different flow speeds to optimize the closure of the cavity. Cavity gas flux, thickness, frictional loads, and cavity pressures were measured over a range of flow speeds and air injection fluxes. High-speed video was used extensively to investigate the unsteady three dimensional cavity closure, the overall cavity shape and oscillations.

  10. Vertical and horizontal test results of 3.9-GHz accelerating cavities at FNAL

    Khabiboulline, T.; Edwards, H.; Foley, M.; Harms, E.; Hocker, James Andrew; Mitchell, D.; Rowe, A.; Solyak, N.; /Fermilab

    2008-06-01

    The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve the beam performance of the VUV FEL, FLASH. In the frame of a collaborative agreement, Fermilab will provide DESY with a cryomodule containing a string of four cavities. Seven 9-cell Nb cavities were tested and six of them did reach accelerating gradient up to 24 MV/m almost twice more than design value of 14 MV/m. Two of these cavities are with new HOM couplers with improved design. In this paper we present all results of the vertical and horizontal tests.

  11. Improving the efficiency of microwave devices with a double output cavity

    Eppley, K.R.; Herrmannsfeldt, W.B.; Lee, T.G.

    1986-05-01

    Double output cavities have been used experimentally to increase the efficiency of high-power klystrons. We have used particle-in-cell simulations with the 2 + 1/2 dimensional code MASK to optimize the design of double output cavities for the lasertron and the 50 MW klystron under development at SLAC. We discuss design considerations for double output cavities (e.g., optimum choice of voltages and phases, efficiency, wall interception, breakdown). We describe how one calculates the cavity impedance matrix from the gap voltages and phases. Simulation results are compared to experience with the 150 MW klystron

  12. Self-similar photonic crystal cavity with ultrasmall mode volume for single-photon nonlinearities

    Choi, Hyeongrak; Heuck, Mikkel; Englund, Dirk

    2017-01-01

    We propose a photonic crystal cavity design with self-similar structure to achieve ultrasmall mode volume. We describe the concept with a silicon-air nanobeam cavity at λ ∼ 1550nm, reaching a mode volume of ∼ 7.01 × 10∼5λ3.......We propose a photonic crystal cavity design with self-similar structure to achieve ultrasmall mode volume. We describe the concept with a silicon-air nanobeam cavity at λ ∼ 1550nm, reaching a mode volume of ∼ 7.01 × 10∼5λ3....

  13. Numerical demonstration of neuromorphic computing with photonic crystal cavities.

    Laporte, Floris; Katumba, Andrew; Dambre, Joni; Bienstman, Peter

    2018-04-02

    We propose a new design for a passive photonic reservoir computer on a silicon photonics chip which can be used in the context of optical communication applications, and study it through detailed numerical simulations. The design consists of a photonic crystal cavity with a quarter-stadium shape, which is known to foster interesting mixing dynamics. These mixing properties turn out to be very useful for memory-dependent optical signal processing tasks, such as header recognition. The proposed, ultra-compact photonic crystal cavity exhibits a memory of up to 6 bits, while simultaneously accepting bitrates in a wide region of operation. Moreover, because of the inherent low losses in a high-Q photonic crystal cavity, the proposed design is very power efficient.

  14. Development of an advanced electropolishing setup for multicell high gradient niobium cavities

    F. Éozénou

    2012-08-01

    Full Text Available Reproducible operation at high performances of superconducting cavities is required for linear accelerators. High beta elliptical cavities are thus of concern and, to achieve required performances for such resonators, surface preparation including electropolishing is recommended. We have designed and operate a setup for electropolishing in the vertical position of multicell cavities in order to: (i obtain high yield with large elliptical cavities for Superconducting Linac (SPL or European Spallation Source projects; (ii develop a reference installation demonstrating that this process is appropriate for the large scale treatment of cavities in industry. The setup described here is the first one able to electropolish vertically multicell cavities with circulating acid and high safety standards. This equipment makes it possible to use a wide range of parameters such as voltage, acid flow rate, temperature, and nitrogen injection with an R&D purpose in mind. Optimization is studied using modeling with COMSOL software for different cavities. As examples, we present some results for the 704 MHz high-beta SPL cavity and the 1300 MHz International Linear Collider cavity and show the influence of cathode shape on both acid flow and electric field distribution during the process. Importance of the size of the cavity and first results achieved on single-cell and nine-cell cavities will be discussed.

  15. Thermal conditions within tree cavities in ponderosa pine (Pinus ponderosa) forests: potential implications for cavity users

    Vierling, Kerri T.; Lorenz, Teresa J.; Cunningham, Patrick; Potterf, Kelsi

    2017-11-01

    Tree cavities provide critical roosting and breeding sites for multiple species, and thermal environments in these cavities are important to understand. Our objectives were to (1) describe thermal characteristics in cavities between June 3 and August 9, 2014, and (2) investigate the environmental factors that influence cavity temperatures. We placed iButtons in 84 different cavities in ponderosa pine (Pinus ponderosa) forests in central Washington, and took hourly measurements for at least 8 days in each cavity. Temperatures above 40 °C are generally lethal to developing avian embryos, and 18% of the cavities had internal temperatures of ≥ 40 °C for at least 1 h of each day. We modeled daily maximum cavity temperature, the amplitude of daily cavity temperatures, and the difference between the mean internal cavity and mean ambient temperatures as a function of several environmental variables. These variables included canopy cover, tree diameter at cavity height, cavity volume, entrance area, the hardness of the cavity body, the hardness of the cavity sill (which is the wood below the cavity entrance which forms the barrier between the cavity and the external environment), and sill width. Ambient temperature had the largest effect size for maximum cavity temperature and amplitude. Larger trees with harder sills may provide more thermally stable cavity environments, and decayed sills were positively associated with maximum cavity temperatures. Summer temperatures are projected to increase in this region, and additional research is needed to determine how the thermal environments of cavities will influence species occupancy, breeding, and survival.

  16. Red-cockaded woodpecker nest-cavity selection: relationships with cavity age and resin production

    Richard N. Conner; Daniel Saenz; D. Craig Rudolph; William G. Ross; David L. Kulhavy

    1998-01-01

    The authors evaluated selection of nest sites by male red-cockaded woodpeckers (Picoides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpeckers were available and when both naturally excavated cavities and artificial cavities were available. They also evaluated nest-cavity selection relative to the ability of naturally...

  17. CEBAF's SRF cavity manufacturing experience

    Benesch, J.F.; Reece, C.E.

    1994-01-01

    Construction of the Continuous Electron Beam Accelerator Facility (CEBAF) recirculating linac represents the largest scale application of superconducting rf (SRF) technology to date. The accelerating structures in CEBAF are 169 pairs of 1.5 GHz superconducting rf cavities -- 9 pairs in an injector and 80 pairs each in two linacs. The beam is to be recirculated up to five passes through each linac. Data is presented on mechanical tolerances achieved by the industrial fabricator of the rf cavities (Siemens). Liquid helium leak rates integrated over 22 vacuum seals have been measured on over 110 cavity pairs. A roughly normal distribution of the log 10 (leak rate) is seen, centered about a rate of 10 -10.4 torr-l/s. Over 140 pairs of the cavities have been assembled and have completed rf testing at 2.0 K. Among these, 54% demonstrated usable accelerating gradients greater than 10 MV/m. Although the rf performance characteristics well exceed the CEBAF baseline requirements of 5 MV/m at Q 0 = 2.4x10 9 , the usual limiting phenomena are encountered: field emission, quenching, and occasional multipacting. A discussion of the occurrence conditions and severity of these phenomena during production cavity testing is presented. The frequency with which performance is limited by quenching suggests that additional material advances may be required for applications which require the reliable achievement of accelerating gradients of more than 15 MV/m

  18. Coupling of an overdriven cavity

    Garbin, H.D.

    1993-01-01

    It is well known that when a nuclear test is conducted in a sufficiently large cavity, the resulting seismic signal is sharply reduced when compared to a normal tamped event. Cavity explosions are of interest in the seismic verification community because of this possibility of reducing the seismic energy generated which can lower signal amplitudes and make detection difficult. Reduced amplitudes would also lower seismic yield estimates which has implications in a Threshold Test Ban Treaty (TTBT). In the past several years, there have been a number of nuclear tests at NTS (Nevada Test Site) inside hemispherical cavities. Two such tests were MILL YARD and MISTY ECHO which had instrumentation at the surface and in the free-field. These two tests differ in one important aspect. MILL YARD was completely decoupled i.e., the cavity wall behaved in an elastic manner. It was estimated that MILL YARD's ground motion was reduced by a factor of at least 70. In contrast, MISTY ECHO was detonated in a hemispherical cavity with the same dimensions as MILL YARD, but with a much larger device yield. This caused an inelastic behavior on the wall and the explosion was not fully decoupled

  19. Coupled superconducting resonant cavities for a heavy ion linac

    Shepard, K W [Argonne National Lab., IL (United States); Roy, A [Nuclear Science Center, New Delhi (India)

    1992-11-01

    A design for a superconducting niobium slow-wave accelerating structure has been explored that may have performance and cost advantages over existing technology. The option considered is an array of pairs of quarter-wave coaxial-line resonant cavities, the two elements of each pair strongly coupled through a short superconducting transmission line. In the linac formed by such an array, each paired structure is independently phased. A disadvantage of two-gap slow wave structures is that each cavity is relatively short, so that a large number of independently-phased elements is required for a linac. Increasing the number of drift tubes per cavity reduces the number of independently-phased elements but at the cost of reducing the range of useful velocity acceptance for each element. Coupling two cavities splits the accelerating rf eigenmode into two resonant modes each of which covers a portion of the full velocity acceptance range of the original, single cavity mode. Using both of these resonant modes makes feasible the use of coupled cavity pairs for a linac with little loss in velocity acceptance. (Author) 2 figs., 8 refs.

  20. Coupled superconducting resonant cavities for a heavy ion linac

    Shepard, K.W.; Roy, A.

    1992-01-01

    A design for a superconducting niobium slow-wave accelerating structure has been explored that may have performance and cost advantages over existing technology. The option considered is an array of pairs of quarter-wave coaxial-line resonant cavities, the two elements of each pair strongly coupled through a short superconducting transmission line. In the linac formed by such an array, each paired structure is independently phased. A disadvantage of two-gap slow wave structures is that each cavity is relatively short, so that a large number of independently-phased elements is required for a linac. Increasing the number of drift tubes per cavity reduces the number of independently-phased elements but at the cost of reducing the range of useful velocity acceptance for each element. Coupling two cavities splits the accelerating rf eigenmode into two resonant modes each of which covers a portion of the full velocity acceptance range of the original, single cavity mode. Using both of these resonant modes makes feasible the use of coupled cavity pairs for a linac with little loss in velocity acceptance. (Author) 2 figs., 8 refs

  1. An Automated 476 MHz RF Cavity Processing Facility at SLAC

    McIntosh, P; Schwarz, H

    2003-01-01

    The 476 MHz accelerating cavities currently used at SLAC are those installed on the PEP-II B-Factory collider accelerator. They are designed to operate at a maximum accelerating voltage of 1 MV and are routinely utilized on PEP-II at voltages up to 750 kV. During the summer of 2003, SPEAR3 will undergo a substantial upgrade, part of which will be to replace the existing 358.54 MHz RF system with essentially a PEP-II high energy ring (HER) RF station operating at 476.3 MHz and 3.2 MV (or 800 kV/cavity). Prior to installation, cavity RF processing is required to prepare them for use. A dedicated high power test facility is employed at SLAC to provide the capability of conditioning each cavity up to the required accelerating voltage. An automated LabVIEW based interface controls and monitors various cavity and test stand parameters, increasing the RF fields accordingly such that stable operation is finally achieved. This paper describes the high power RF cavity processing facility, highlighting the features of t...

  2. Experimental investigation of turbine disk cavity aerodynamics and heat transfer

    Daniels, W. A.; Johnson, B. V.

    1993-01-01

    An experimental investigation of turbine disk cavity aerodynamics and heat transfer was conducted to provide an experimental data base that can guide the aerodynamic and thermal design of turbine disks and blade attachments for flow conditions and geometries simulating those of the space shuttle main engine (SSME) turbopump drive turbines. Experiments were conducted to define the nature of the aerodynamics and heat transfer of the flow within the disk cavities and blade attachments of a large scale model simulating the SSME turbopump drive turbines. These experiments include flow between the main gas path and the disk cavities, flow within the disk cavities, and leakage flows through the blade attachments and labyrinth seals. Air was used to simulate the combustion products in the gas path. Air and carbon dioxide were used to simulate the coolants injected at three locations in the disk cavities. Trace amounts of carbon dioxide were used to determine the source of the gas at selected locations on the rotors, the cavity walls, and the interstage seal. The measurements on the rotor and stationary walls in the forward and aft cavities showed that the coolant effectiveness was 90 percent or greater when the coolant flow rate was greater than the local free disk entrainment flow rate and when room temperature air was used as both coolant and gas path fluid. When a coolant-to-gas-path density ratio of 1.51 was used in the aft cavity, the coolant effectiveness on the rotor was also 90 percent or greater at the aforementioned condition. However, the coolant concentration on the stationary wall was 60 to 80 percent at the aforementioned condition indicating a more rapid mixing of the coolant and flow through the rotor shank passages. This increased mixing rate was attributed to the destabilizing effects of the adverse density gradients.

  3. A SURVEY OF CORONAL CAVITY DENSITY PROFILES

    Fuller, J.; Gibson, S. E.

    2009-01-01

    Coronal cavities are common features of the solar corona that appear as darkened regions at the base of coronal helmet streamers in coronagraph images. Their darkened appearance indicates that they are regions of lowered density embedded within the comparatively higher density helmet streamer. Despite interfering projection effects of the surrounding helmet streamer (which we refer to as the cavity rim), Fuller et al. have shown that under certain conditions it is possible to use a Van de Hulst inversion of white-light polarized brightness (pB) data to calculate the electron density of both the cavity and cavity rim plasma. In this article, we apply minor modifications to the methods of Fuller et al. in order to improve the accuracy and versatility of the inversion process, and use the new methods to calculate density profiles for both the cavity and cavity rim in 24 cavity systems. We also examine trends in cavity morphology and how departures from the model geometry affect our density calculations. The density calculations reveal that in all 24 cases the cavity plasma has a flatter density profile than the plasma of the cavity rim, meaning that the cavity has a larger density depletion at low altitudes than it does at high altitudes. We find that the mean cavity density is over four times greater than that of a coronal hole at an altitude of 1.2 R sun and that every cavity in the sample is over twice as dense as a coronal hole at this altitude. Furthermore, we find that different cavity systems near solar maximum span a greater range in density at 1.2 R sun than do cavity systems near solar minimum, with a slight trend toward higher densities for systems nearer to solar maximum. Finally, we found no significant correlation of cavity density properties with cavity height-indeed, cavities show remarkably similar density depletions-except for the two smallest cavities that show significantly greater depletion.

  4. Review of cavity optomechanical cooling

    Liu Yong-Chun; Hu Yu-Wen; Xiao Yun-Feng; Wong Chee Wei

    2013-01-01

    Quantum manipulation of macroscopic mechanical systems is of great interest in both fundamental physics and applications ranging from high-precision metrology to quantum information processing. For these purposes, a crucial step is to cool the mechanical system to its quantum ground state. In this review, we focus on the cavity optomechanical cooling, which exploits the cavity enhanced interaction between optical field and mechanical motion to reduce the thermal noise. Recent remarkable theoretical and experimental efforts in this field have taken a major step forward in preparing the motional quantum ground state of mesoscopic mechanical systems. This review first describes the quantum theory of cavity optomechanical cooling, including quantum noise approach and covariance approach; then, the up-to-date experimental progresses are introduced. Finally, new cooling approaches are discussed along the directions of cooling in the strong coupling regime and cooling beyond the resolved sideband limit. (topical review - quantum information)

  5. WAVEGUIDE COUPLER KICK TO BEAM BUNCH AND CURRENT DEPENDENCY ON SRF CAVITIES

    Genfa Wu; Haipeng Wang; Charles Reece; Robert Rimmer

    2008-01-01

    JLAB SRF cavities employ waveguide type fundamental power couplers (FPC). The FPC design for the 7-cell upgrade cavities was optimized to minimize the dipole field kick. For continuous wave (CW) operation, the forwarding RF power will be at different magnitude to drive the different beam current and cavity gradient. This introduces some deviation from optimized FPC field for varying beam loading. This article analyzes the beam behavior both in centroid kick and head-tail kick under different beam loading conditions

  6. RF cavity for the Novosibirsk race-track microtron-recuperator

    Gavrilov, N.; Kuptsov, I.; Kurkin, G.; Mironenko, L.; Petrov, V.; Sedlyarov, I.; Veshcherevich, V.

    1994-01-01

    Geometry, engineering design and characteristics of a 181 MHz RF cavity are described. The cavity has copper clad stainless steel walls and has a Q of 42,000 and a shunt impedance of 8.5 MOhm. The cavities of that type are parts of an RF system of a CW race-track microtron-recuperator (RTMR). 10 refs.; 16 figs.; 1 tab

  7. Efficient quality-eactor estimation of a vertical cavity employing a high-contrast grating

    Taghizadeh, Alireza; Mørk, Jesper; Chung, Il-Sug

    2017-01-01

    Hybrid vertical cavity lasers employing high-contrast grating reflectors are attractive for Si-integrated light source applications. Here, a method for reducing a three-dimensional (3D) optical simulation of this laser structure to lower-dimensional simulations is suggested, which allows for very...... fast and approximate analysis of the quality-factor of the 3D cavity. This approach enables us to efficiently optimize the laser cavity design without performing cumbersome 3D simulations....

  8. On niobium sputter coated cavities

    Arnolds-Mayer, G.; Kaufmann, U.; Downar, H.

    1988-01-01

    To coat copper cavities with a thin film of niobium, facilities for electropolishing and sputter deposition have been installed at Dornier. Experiments have been performed on samples to optimize electropolishing and deposition parameters. In this paper, characteristics concerning surface properties, adhesion of the niobium film to the copper substrate, and film properties were studied on planar samples. A 1.5 GHz single cell cavity made from oxygen free high conductivity (OFHC) copper was sputter coated twice. First rf measurements were performed in the temperature range from 300 K to 2 K

  9. Frequency tuning of the CEBAF upgrade cavities

    J.R. Delayen; L. Doolittle; E. Feldl; V. Nguyen; W. Sachleben

    1999-01-01

    Long-term plans for CEBAF at Jefferson Lab calls for achieving 12 GeV in the middle of the next decade and 24 GeV after 2010. In support of these plans, an Upgrade Cryomodule capable of providing more than twice the voltage of the existing ones is under development. One requirement is to operate the superconducting cavities, which are 40% longer than existing ones, at 2.5 times the original design gradient with the same amount of rf power. This puts stringent requirements on the accuracy of the frequency tuner: range of 400 kHz and resolution of 1 Hz. A new tuner design to meet these requirements is under development. This system avoids problem areas of previous designs by holding to the principles of not placing moving parts in the vacuum and/or low temperature space, and of having all drive components readily accessible for maintenance and replacement without cryomodule warm-up

  10. Compact and highly efficient laser pump cavity

    Chang, Jim J.; Bass, Isaac L.; Zapata, Luis E.

    1999-01-01

    A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

  11. Slot-coupled CW standing wave accelerating cavity

    Wang, Shaoheng; Rimmer, Robert; Wang, Haipeng

    2017-05-16

    A slot-coupled CW standing wave multi-cell accelerating cavity. To achieve high efficiency graded beta acceleration, each cell in the multi-cell cavity may include different cell lengths. Alternatively, to achieve high efficiency with acceleration for particles with beta equal to 1, each cell in the multi-cell cavity may include the same cell design. Coupling between the cells is achieved with a plurality of axially aligned kidney-shaped slots on the wall between cells. The slot-coupling method makes the design very compact. The shape of the cell, including the slots and the cone, are optimized to maximize the power efficiency and minimize the peak power density on the surface. The slots are non-resonant, thereby enabling shorter slots and less power loss.

  12. Conduction cooling systems for linear accelerator cavities

    Kephart, Robert

    2017-05-02

    A conduction cooling system for linear accelerator cavities. The system conducts heat from the cavities to a refrigeration unit using at least one cavity cooler interconnected with a cooling connector. The cavity cooler and cooling connector are both made from solid material having a very high thermal conductivity of approximately 1.times.10.sup.4 W m.sup.-1 K.sup.-1 at temperatures of approximately 4 degrees K. This allows for very simple and effective conduction of waste heat from the linear accelerator cavities to the cavity cooler, along the cooling connector, and thence to the refrigeration unit.

  13. Cryogenic system for TRISTAN superconducting RF cavities

    Hosoyama, K.; Hara, K.; Kabe, A.; Kojima, Y.; Ogitsu, T.; Sakamoto, Y.; Kawamura, S.; Matsumoto, K.

    1993-01-01

    A large cryogenic system has been designed, constructed and operated in the TRISTAN electron-positron collider at KEK for 508 MHz, 32x5-cell superconducting RF cavities. A 6.5 kW, 4.4 K helium refrigerator with 5 turbo-expanders on the ground level supplies liquid helium in parallel to the 16 cryostats in the TRISTAN tunnel through about 250 m long multichannel transfer line. Two 5-cell cavities are coupled together, enclosed in a cryostat and cooled by about 830 L pool boiling liquid helium. A liquid nitrogen circulation system with a turbo-expander has been adopted for 80 K radiation shields in the multichannel transfer line and the cryostats to reduce liquid nitrogen consumption and to increase the operation stability of the system. The cryogenic system has a total of about 18 000 hours of operating time from the first cool down test in August 1988 to November 1991. The design principle and outline of the cryogenic system and the operational experience are presented. (orig.)

  14. Sterility of the uterine cavity

    Møller, Birger R.; Kristiansen, Frank V.; Thorsen, Poul

    1995-01-01

    from the same sites. Nearly a quarter of all the patients harbored one or more microorganisms in the uterus, mostly Gardnerella vaginalis, Enterobacter and Streptococcus agalactiae. We found that in a significant number of cases, the uterine cavity is colonized with potentially pathogenic organisms...

  15. Flux trapping in superconducting cavities

    Vallet, C.; Bolore, M.; Bonin, B.; Charrier, J.P.; Daillant, B.; Gratadour, J.; Koechlin, F.; Safa, H.

    1992-01-01

    The flux trapped in various field cooled Nb and Pb samples has been measured. For ambient fields smaller than 3 Gauss, 100% of the flux is trapped. The consequences of this result on the behavior of superconducting RF cavities are discussed. (author) 12 refs.; 2 figs

  16. Field emission in RF cavities

    Bonin, B.

    1996-01-01

    Electron field emission limits the accelerating gradient in superconducting cavities. It is shown how and why it is an important problem. The phenomenology of field emission is then described, both in DC and RF regimes. Merits of a few plausible 'remedies' to field emission are discussed. (author)

  17. Superconducting cavity development at RRCAT

    Joshi, S.C.

    2015-01-01

    Raja Ramanna Centre for Advanced Technology (RRCAT), Indore pursuing a program on 'R and D Activities for High Energy Proton Linac based Spallation Neutron Source'. Spallation neutron source (SNS) facility will provide high flux pulse neutrons for research in the areas of condensed matter physics, materials science, chemistry, biology and engineering. This will complement the existing synchrotron light source facility, INDUS-2 at RRCAT and reactor based neutron facilities at BARC. RRCAT is also participating in approved mega project on 'Physics and Advanced Technology for High Intensity Proton Accelerator' to support activities of Indian Institutions - Fermilab Collaboration (IIFC). The SNS facility will have a 1 GeV superconducting proton injector linac and 1 GeV accumulator ring. The linac will comprise of large number of superconducting radio-frequency (SCRF) cavities operating at different RF frequencies housed in suitable cryomodules. Thus, an extensive SCRF cavity infrastructure setup is being established. In addition, a scientific and technical expertise are also being developed for fabrication, processing and testing of the SCRF cavities for series production. The paper presents the status of superconducting cavity development at RRCAT

  18. Thoracic cavity after thoracic operations

    Rabkin, I.Kh.

    1983-01-01

    The problems of roentgenologic method application to detect postoperative c omplications in pulmonary tissue, bronchi, pleural cavity, mediastinum, have been considered. It is shown, that the use of the above mentioned method permit s to judge on the rates and degrees of the lungs straightening, anatomic structures shift, the change in air- and blood-filling, accumulation of liquid a nd air in pleuritic

  19. "Grinding" cavities in polyurethane foam

    Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

    1980-01-01

    Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

  20. Droplet based cavities and lasers

    Mølhave, Kristian; Kristensen, Anders; Mortensen, Asger

    2009-01-01

    The self-organized and molecularly smooth surface on liquid microdroplets makes them attractive as optical cavities with very high quality factors. This chapter describes the basic theory of optical modes in spherical droplets. The mechanical properties including vibrational excitation are also d...

  1. Superconducting cavities for beauty factories

    Lengeler, H.

    1992-01-01

    The possibilities and merits of superconducting accelerating cavities for Beauty-factories are considered. There exist already large sc systems of size and frequency comparable to the ones needed for Beauty-factories. Their status and operation experience is discussed. A comparison of normal conducting and superconducting systems is done for two typical Beauty-factory rings

  2. SRF Cavity Fabrication and Materials

    Singer, W [DESY (Germany)

    2014-07-01

    The technological and metallurgical requirements of material for highgradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10μg/g. The hydrogen content should be kept below 2μg/g to prevent degradation of the Q-value under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Defects may be detected by quality control methods such as eddy current scanning and identified by a number of special methods. Conventional and alternative cavity fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and Electron-Beam Welding (EBW). The welding of half-cells is a delicate procedure, requiring intermediate cleaning steps and a careful choice of weld parameters to achieve full penetration of the joints. The equator welds are particularly critical. A challenge for a welded construction is the tight mechanical and electrical tolerances. These can be maintained by a combination of mechanical and radio-frequency measurements on halfcells and by careful tracking of weld shrinkage. The established procedure is suitable for large series production. The main aspects of quality assurance management are mentioned. Another cavity fabrication approach is slicing discs from the ingot and producing cavities by deep drawing and EBW. Accelerating gradients at the level of 35–45 MV·m–1 can be achieved by applying Electropolishing (EP) treatment. Furthermore, the single-crystal option (grain boundary free) is promising. It seems that in this case, high performance can be achieved by a simplified treatment procedure. Fabrication of the

  3. A novel technique for tuning of co-axial cavity of multi-beam klystron

    Saha, Sukalyan, E-mail: sstechno18@gmail.com; Bandyopadhyay, Ayan Kumar; Pal, Debashis; Kant, Deepender; Joshi, Lalit Mohan; Kumar, Bijendra; Meena, Rakesh; Rawat, Vikram [Microwave Tubes Division, CSIR-CEERI, Pilani, Rajasthan-333031 (India)

    2016-03-09

    Multi-beam Klystrons (MBKs) have gained wide acceptances in the research sector for its inherent advantages. But developing a robust tuning technique for an MBK cavity of coaxial type has still remained a challenge as these designs are very prone to suffer from asymmetric field distribution with inductive tuning of the cavity. Such asymmetry leads to inhomogeneous beam-wave interaction, an undesirable phenomenon. Described herein is a new type of coaxial cavity that has the ability to suppress the asymmetry, thereby allowing tuning of the cavity with a single tuning post.

  4. Electrodynamic characterisitcs measurements of higher order modes in S-band cavity

    Donetsky, R.; Lalayan, M.; Sobenin, N. P.; Orlov, A.; Bulygin, A.

    2017-12-01

    The 800 MHz superconducting cavities with grooved beam pipes were suggested as one of the harmonic cavities design options for High Luminosity LHC project. Cavity simulations were carried out and scaled aluminium prototype having operational mode frequency of 2400 MHz was manufactured for testing the results of simulations. The experimental measurements of transverse shunt impedance with error estimation for higher order modes TM 110 and TE 111 for S-band elliptical cavity were done. The experiments using dielectric and metallic spherical beads and with ring probe were carried out. The Q-factor measurements for two-cell structure and array of two cells were carried out.

  5. Concept of multiple-cell cavity for axion dark matter search

    Jeong, Junu; Youn, SungWoo; Ahn, Saebyeok; Kim, Jihn E.; Semertzidis, Yannis K.

    2018-02-01

    In cavity-based axion dark matter search experiments exploring high mass regions, multiple-cavity design is under consideration as a method to increase the detection volume within a given magnet bore. We introduce a new idea, referred to as a multiple-cell cavity, which provides various benefits including a larger detection volume, simpler experimental setup, and easier phase-matching mechanism. We present the characteristics of this concept and demonstrate the experimental feasibility with an example of a double-cell cavity.

  6. Non-destructive splitter of twisted light based on modes splitting in a ring cavity.

    Li, Yan; Zhou, Zhi-Yuan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

    2016-02-08

    Efficiently discriminating beams carrying different orbital angular momentum (OAM) is of fundamental importance for various applications including high capacity optical communication and quantum information processing. We design and experimentally verify a distinguished method for effectively splitting different OAM-carried beams by introducing Dove prisms in a ring cavity. Because of rotational symmetry broken of two OAM-carried beams with opposite topological charges, their transmission spectra will split. When mode and impedance matches between the cavity and one OAM-carried beam are achieved, this beam will transmit through the cavity and other beam will be reflected, both beams keep their spatial shapes. In this case, the cavity acts like a polarized beam splitter. Besides, the transmitting beam can be selected at your will, the splitting efficiency can reach unity if the cavity is lossless and it completely matches the beam. Furthermore, beams carry multi-OAMs can also be split by cascading ring cavities.

  7. Study of Low Work Function Materials for Hot Cavity Resonance Ionization Laser Ion Sources

    Catherall, R; Fedosseev, V; Marsh, B; Mattolat, C; Menna, Mariano; Österdahl, F; Raeder, S; Schwellnus, F; Stora, T; Wendt, K; CERN. Geneva. AB Department

    2008-01-01

    The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization on the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high-temperature, low-work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE / CERN, Geneva and RISIKO / University of Mainz.

  8. Study of low work function materials for hot cavity resonance ionization laser ion sources

    Schwellnus, F; Crepieux, B; Fedosseev, V N; Marsh, B A; Mattolat, Ch; Menna, M; Österdahl, F K; Raeder, S; Stora, T; Wendta, K

    2009-01-01

    The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization of the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high temperature, low work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE/CERN, Geneva and RISIKO/University of Mainz.

  9. Waveguide based external cavity semiconductor lasers

    Oldenbeuving, Ruud; Klein, E.J.; Offerhaus, Herman L.; Lee, Christopher James; Verhaegen, M.; Boller, Klaus J.

    2012-01-01

    We report on progress of the project waveguide based external cavity semiconductor laser (WECSL) arrays. Here we present the latest results on our efforts to mode lock an array of tunable, external cavity semiconductor lasers.

  10. Optical cavity furnace for semiconductor wafer processing

    Sopori, Bhushan L.

    2014-08-05

    An optical cavity furnace 10 having multiple optical energy sources 12 associated with an optical cavity 18 of the furnace. The multiple optical energy sources 12 may be lamps or other devices suitable for producing an appropriate level of optical energy. The optical cavity furnace 10 may also include one or more reflectors 14 and one or more walls 16 associated with the optical energy sources 12 such that the reflectors 14 and walls 16 define the optical cavity 18. The walls 16 may have any desired configuration or shape to enhance operation of the furnace as an optical cavity 18. The optical energy sources 12 may be positioned at any location with respect to the reflectors 14 and walls defining the optical cavity. The optical cavity furnace 10 may further include a semiconductor wafer transport system 22 for transporting one or more semiconductor wafers 20 through the optical cavity.

  11. Research and development for electropolishing of Nb for ILC accelerator cavities

    Kelley, Michael J.

    2009-01-01

    The objectives of this project are to 1, Expand the scientific and technological understanding of the effect of post-treatment (electropolish, buffered chemical polish, low-temperature baking) on the surface of niobium; 2, Relate the knowledge to the performance of niobium superconducting radiofrequency accelerator cavities; and, 3, Thereby design and demonstrate an electropolish process that can be applied to complete cavities

  12. Vertical-cavity surface-emitting lasers for medical diagnosis

    Ansbæk, Thor

    This thesis deals with the design and fabrication of tunable Vertical-Cavity Surface-Emitting Lasers (VCSELs). The focus has been the application of tunable VCSELs in medical diagnostics, specifically OCT. VCSELs are candidates as light sources for swept-source OCT where their high sweep rate, wide...

  13. Cavity QED experiments with ion Coulomb crystals

    Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan

    2009-01-01

    Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....

  14. An economical wireless cavity-nest viewer

    Daniel P. Huebner; Sarah R. Hurteau

    2007-01-01

    Inspection of cavity nests and nest boxes is often required during studies of cavity-nesting birds, and fiberscopes and pole-mounted video cameras are sometimes used for such inspection. However, the cost of these systems may be prohibitive for some potential users. We describe a user-built, wireless cavity viewer that can be used to access cavities as high as 15 m and...

  15. Wideband perfect coherent absorber based on white-light cavity

    Kotlicki, Omer; Scheuer, Jacob

    2015-03-01

    Coherent Perfect Absorbers (CPAs) are optical cavities which can be described as time-reversed lasers where light waves that enter the cavity, coherently interfere and react with the intra-cavity losses to yield perfect absorption. In contrast to lasers, which benefit from high coherency and narrow spectral linewidths, for absorbers these properties are often undesirable as absorption at a single frequency is highly susceptible to spectral noise and inappropriate for most practical applications. Recently, a new class of cavities, characterized by a spectrally wide resonance has been proposed. Such resonators, often referred to as White Light Cavities (WLCs), include an intra-cavity superluminal phase element, designed to provide a phase response with a slope that is opposite in sign and equal in magnitude to that of light propagation through the empty cavity. Consequently, the resonance phase condition in WLCs is satisfied over a band of frequencies providing a spectrally wide resonance. WLCs have drawn much attention due to their attractiveness for various applications such as ultra-sensitive sensors and optical buffering components. Nevertheless, WLCs exhibit inherent losses that are often undesirable. Here we introduce a simple wideband CPA device that is based on the WLC concept along with a complete analytical analysis. We present analytical and FDTD simulations of a practical, highly compact (12µm), Silicon based WLC-CPA that exhibits a flat and wide absorption profile (40nm) and demonstrate its usefulness as an optical pulse terminator (>35db isolation) and an all optical modulator that span the entire C-Band and exhibit high immunity to spectral noise.

  16. Docking of Antibodies into Cavities in DNA Origami

    Quyang, X; Stefano, Mattia De; Krissanaprasit, Abhichart

    2017-01-01

    -selective immobilization of antibodies in designed cavities in 2D and 3D DNA origami structures. Two tris(NTA) modified strands are inserted into the cavity to form NTA-metal complexes with histidine clusters on the Fc domain. Subsequent covalent linkage to the antibody was achieved by coupling to lysines. Atomic force...... microscopy (AFM) and transmission electron microscopy (TEM) validated efficient antibody immobilization in the origami structures. The increased ability to control the orientation of antibodies in nanostructures and at surfaces has potential for directing the interactions of antibodies with targets...

  17. High-repetition intra-cavity source of Compton radiation

    Pogorelsky, I; Polyanskiy, M; Agustsson, R; Campese, T; Murokh, A; Ovodenko, A; Shaftan, T

    2014-01-01

    We report our progress in developing a high-power Compton source for a diversity of applications ranging from university-scale compact x-ray light sources and metrology tools for EUV lithography, to high-brilliance gamma-sources for nuclear analysis. Our conceptual approach lies in multiplying the source’s repetition rate and increasing its average brightness by placing the Compton interaction point inside the optical cavity of an active laser. We discuss considerations in its design, our simulations, and tests of the laser’s cavity that confirm the feasibility of the proposed concept. (paper)

  18. Deep drawing experiences of niobium disk for PEFP SRF cavity prototype

    Kim, Han Sung; An, Sun; Zhang, Liping; Tang, Yazhe; Li, Ying Min; Kwon, Hyeok Jung; Cho, Yong Sub

    2009-01-01

    A superconducting radio frequency (SRF) cavity with a geometrical beta of 0.42 has been designed to accelerate a proton beam after 100 MeV for an extension of Proton Engineering Frontier Project (PEFP). The designed cavity shape is an elliptical and the resonant frequency is 700 MHz. In order to confirm the RF and mechanical properties of the cavity, two prototypes of copper cavities have been fabricated and tested. Based on the experiences gained with the copper prototypes, two niobium prototypes have been designed. One is two-cell cavity and the other is five cell cavity. The two-cell cavity is for finalizing the niobium cavity production procedure and testing the cavity RF properties at a low temperature and moderate power level. The five-cell cavity is for checking the production quality and testing vertical test system in the future. Both of them are under fabrication. Through the fabrication of the niobium prototype, several issues such as deep drawing, electron beam welding and surface treatment will be addressed. The drawing of the PEPF SRF low beta cavity is shown in Fig. 1. Major parameters for the cavity are like following. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 per cavity - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m - Field flatness: 1.56 % - Cell to cell coupling: 1.41 % - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Lorentz force detuning: 0.4 Hz/(MV/m)2 - Stiffening structure: Double ring - Effective length: 0.45 m - External Q of FPC: 8.0E5 ±20 % - HOM load: less than 2 W - HOM Qext requirement: less than 3.0E5 At present, all the niobium disk and plates for cavity and NbTi flanges for beam pipe flange are prepared

  19. Nanometer cavities studied by positron annihilation

    Mogensen, O.E.

    1992-01-01

    Positronium (Ps) is trapped in cavities in insulating solids, and the lifetime of ortho Ps is determined by the size of the cavity. The information on the properties of the cavities obtained by use of the standard slow positron beam and the 'normal' positron annihilation techniques is compared for several selected cases. (author)

  20. Diagram of a LEP superconducting cavity

    1991-01-01

    This diagram gives a schematic representation of the superconducting radio-frequency cavities at LEP. Liquid helium is used to cool the cavity to 4.5 degrees above absolute zero so that very high electric fields can be produced, increasing the operating energy of the accelerator. Superconducting cavities were used only in the LEP-2 phase of the accelerator, from 1996 to 2000.

  1. A Many-Atom Cavity QED System with Homogeneous Atom-Cavity Coupling

    Lee, Jongmin; Vrijsen, Geert; Teper, Igor; Hosten, Onur; Kasevich, Mark A.

    2013-01-01

    We demonstrate a many-atom-cavity system with a high-finesse dual-wavelength standing wave cavity in which all participating rubidium atoms are nearly identically coupled to a 780-nm cavity mode. This homogeneous coupling is enforced by a one-dimensional optical lattice formed by the field of a 1560-nm cavity mode.

  2. High-power RF cavity R ampersand D for the PEP-II B Factory

    Rimmer, R.; Lambertson, G.; Hodgson, J.

    1994-06-01

    We describe the development of a high-power test model of the 476 MHz RF cavity for the PEP-II B Factory. This cavity is designed to demonstrate the feasibility of a high-power design with higher-order mode (HOM) damping waveguides and the fabrication technologies involved, and it can also be used to evaluate aperture or loop couplers and various RF windows. Changes to the RF design to reduce peak surface heating are discussed and results of finite-element analyses of temperature and stress are presented. Fabrication methods for the prototype and subsequent production cavities are discussed

  3. A Spin-Flip Cavity for Microwave Spectroscopy of Antihydrogen

    Federmann, Silke; Widmann, Eberhard

    The present thesis is a contribution to the Asacusa (Atomic Spectroscopy And Collisions Using Slow Antiprotons) experiment. The aim of this experiment is to measure the ground-state hyperfine structure of antihydrogen. This is done using a Rabi-like spectrometer line consisting of an antihydrogen source, a microwave cavity, a sextupole magnet and a detector. The cavity induces spin-flip transitions in the ground-state hyperfine levels of antihydrogen whereas the sextupole magnet selects the antihydrogen atoms according to their spin state. Such a configuration allows the measurements of the hyperfine transition in antihydrogen with very high precision. A comparison with the corresponding transitions in hydrogen would thus provide a very sensitive test of the charge-parity-time (Cpt) symmetry. In the context of this thesis, the central piece of this spectrometer line, the spin flip cavity, was designed and implemented. The delicacy of this task was achieving the required field homogeneity: It needs to be bette...

  4. PEP-II RF Cavity Revisited (LCC-0032)

    Rimmer, R.

    2004-03-23

    This report describes the results of numerical simulations of the PEP-II RF cavity performed after the completion of the construction phase of the project and comparisons are made to previous calculations and measured results. These analyses were performed to evaluate new calculation techniques for the HOM distribution and RF surface heating that were not available at the time of the original design. These include the use of a high frequency electromagnetic element in ANSYS and the new Omega 3P code to study wall losses, and the development of broadband time domain simulation methods in MAFIA for the HOM loading. The computed HOM spectrum is compared with cavity measurements and observed beam-induced signals. The cavity fabrication method is reviewed, with the benefit of hindsight, and simplifications are discussed.

  5. Process Factors Influence on Cavity Pressure Behavior in Microinjection Moulding

    Griffiths, C. A.; Dimov, S. S.; Scholz, S.

    2011-01-01

    about the filling behavior of different polymer melts. In this paper, a pressure sensor mounted inside a tool cavity was employed to analyse maximum cavity pressure, pressure increase rate during filling and pressure work. The influence of four mu IM parameters, melt temperature, mould temperature......Process monitoring of microinjection moulding (mu IM) is of crucial importance when analysing the effect of different parameter settings on the process and then in assessing its quality. Quality factors related to cavity pressure can provide valuable information about the process dynamics and also......, injection speed, and packing pressure on these three pressure-related process parameters was investigated. A design of experiment study was conducted by moulding a test part, a microfluidic component, in three different polymer materials, PP, ABS, and PC. The results show a similar process behavior for all...

  6. Higher order mode damping in Kaon factory RF cavities

    Enegren, T.; Poirier, R.; Griffin, J.; Walling, L.; Thiessen, H.A.; Smythe, W.R.

    1989-05-01

    Proposed designs for Kaon factory accelerators require that the rf cavities support beam currents on the order of several amperes. The beam current has Fourier components at all multiples of the rf frequency. Empty rf buckets produce additional components at all multiples of the revolution frequency. If a Fourier component of the beam coincides with the resonant frequency of a higher order mode of the cavity, which is inevitable if the cavity has a large frequency swing, significant excitation of this mode can occur. The induced voltage may then excite coupled bunch mode instabilities. Effective means are required to damp higher order modes without significantly affecting the fundamental mode. A mode damping scheme based on coupled transmission lines has been investigated and is report

  7. Beam loading and cavity compensation for the ground test accelerator

    Jachim, S.P.; Natter, E.F.

    1989-01-01

    The Ground Test Accelerator (GTA) will be a heavily beam-loaded H/sup minus/ linac with tight tolerances on accelerating field parameters. The methods used in modeling the effects of beam loading in this machine are described. The response of the cavity to both beam and radio-frequency (RF) drive stimulus is derived, including the effects of cavity detuning. This derivation is not restricted to a small-signal approximation. An analytical method for synthesizing a predistortion network that decouples the amplitude and phase responses of the cavity is also outlined. Simulation of performance, including beam loading, is achieved through use of a control system analysis software package. A straightforward method is presented for extrapolating this work to model large coupled structures with closely spaced parasitic modes. Results to date have enabled the RF control system designs for GTA to be optimized and have given insight into their operation. 6 refs., 10 figs

  8. Acoustic cavity transducers for the manipulation of cells and biomolecules

    Tovar, Armando; Patel, Maulik; Lee, Abraham P.

    2010-02-01

    A novel fluidic actuator that is simple to fabricate, integrate, and operate is demonstrated for use within microfluidic systems. The actuator is designed around the use of trapped air bubbles in lateral cavities and the resultant acoustic streaming generated from an outside acoustic energy source. The orientation of the lateral cavities to the main microchannel is used to control the bulk fluid motion within the device. The first order flow generated by the oscillating bubble is used to develop a pumping platform that is capable of driving fluid within a chip. This pump is integrated into a recirculation immunoassay device for enhanced biomolecule binding through fluid flow for convection limited transport. The recirculation system showed an increase in binding site concentration when compared with traditional passive and flow-through methods. The acoustic cavity transducer has also been demonstrated for application in particle switching. Bursts of acoustic energy are used to generate a second order streaming pattern near the cavity interface to drive particles away or towards the cavity. The use of this switching mechanism is being extended to the application of sorting cells and other particles within a microfluidic system.

  9. Study of a spoke cavity for low-beta applications

    Olry, G.; Biarrotte, J.L.; Saugnac, H.; Lesrel, J.

    2003-01-01

    Since a few years, intensive studies have been developed on SC cavities (for instance, spoke-type or reentrant cavities) for their use as accelerating structures in the low energy part of high power proton or ions accelerators (typically from 5 to 100 MeV). Within the framework of the EURISOL (EURopean Isotope Separation On-Line) and XADS (eXperimental Accelerator Driven System) European accelerators projects, IPN Orsay decided to plan a R and D program on low-beta spoke-type cavities. In the major part of this paper, we report on the optimization of the geometry of a β=0.35, 2 gap spoke cavity, aiming at achieving good electromagnetic parameters (i.e. lowest E pk /E acc and B pk /E acc ). A mechanical study is also presented, as well as a preliminary design of a proton spoke Linac (12-85 MeV) composed of β=0.18 and β=0.35, 2 gap cavities. (author)

  10. Gastrophysics of the Oral Cavity.

    Mouritsen, Ole G

    2016-01-01

    Gastrophysics is the science that pertains to the physical and physico-chemical description of the empirical world of gastronomy, with focus on sensory perception in the oral cavity and how it is related to the materials properties of food and cooking processes. Flavor (taste and smell), mouthfeel, chemesthesis, and astringency are all related to the chemical properties and the texture of the food and how the food is transformed in the oral cavity. The present topical review will primarily focus attention on the somatosensory perception of food (mouthfeel or texture) and how it interacts with basic tastes (sour, bitter, sweet, salty, and umami) and chemesthetic action. Issues regarding diet, nutrition, and health will be put into an evolutionary perspective, and some mention will be made of umami and its importance for (oral) health.

  11. Cavity Voltage Phase Modulation MD

    Mastoridis, Themistoklis; Molendijk, John; Timko, Helga; CERN. Geneva. ATS Department

    2016-01-01

    The LHC RF/LLRF system is currently configured for extremely stable RF voltage to minimize transient beam loading effects. The present scheme cannot be extended beyond nominal beam current since the demanded power would exceed the peak klystron power and lead to saturation. A new scheme has therefore been proposed: for beam currents above nominal (and possibly earlier), the cavity phase modulation by the beam will not be corrected (transient beam loading), but the strong RF feedback and One-Turn Delay feedback will still be active for loop and beam stability in physics. To achieve this, the voltage set point will be adapted for each bunch. The goal of this MD was to test a new algorithm that would adjust the voltage set point to achieve the cavity phase modulation that would minimize klystron forward power.

  12. Porous photonic crystal external cavity laser biosensor

    Huang, Qinglan [Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Peh, Jessie; Hergenrother, Paul J. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Cunningham, Brian T. [Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2016-08-15

    We report the design, fabrication, and testing of a photonic crystal (PC) biosensor structure that incorporates a porous high refractive index TiO{sub 2} dielectric film that enables immobilization of capture proteins within an enhanced surface-area volume that spatially overlaps with the regions of resonant electromagnetic fields where biomolecular binding can produce the greatest shifts in photonic crystal resonant wavelength. Despite the nanoscale porosity of the sensor structure, the PC slab exhibits narrowband and high efficiency resonant reflection, enabling the structure to serve as a wavelength-tunable element of an external cavity laser. In the context of sensing small molecule interactions with much larger immobilized proteins, we demonstrate that the porous structure provides 3.7× larger biosensor signals than an equivalent nonporous structure, while the external cavity laser (ECL) detection method provides capability for sensing picometer-scale shifts in the PC resonant wavelength caused by small molecule binding. The porous ECL achieves a record high figure of merit for label-free optical biosensors.

  13. Improvement of cavity performance in the Saclay/Cornell/DESY's SC cavities

    Kako, E.; Noguchi, S.; Ono, M.

    2000-01-01

    Development of 1.3 GHz Nb superconducting cavities for TESLA (TeV Energy Superconducting Linear Collider) has been carried out with international collaboration. Three Saclay single-cell cavities, one Cornell two-cell cavity and one DESY nine-cell cavity were sent to KEK in order to compare the cavity performance. These cavities were tested at KEK after the following surface treatment: 1) high pressure rinsing, HPR, 2) chemical polishing and HPR, 3) electropolishing and HPR. The test results, especially, improvement of the cavity performance due to electropolishing are reported in this paper. (author)

  14. Grinding Inside A Toroidal Cavity

    Mayer, Walter; Adams, James F.; Burley, Richard K.

    1987-01-01

    Weld lines ground smooth within about 0.001 in. Grinding tool for smoothing longitudinal weld lines inside toroidal cavity includes curved tunnel jig to guide grinding "mouse" along weld line. Curvature of tunnel jig matched to shape of toroid so grinding ball in mouse follows circular arc of correct radius as mouse is pushed along tunnel. Tool enables precise control of grindout shape, yet easy to use.

  15. Development of 650 MHz (β=0.9) single-cell SCRF cavity

    Bagre, M.; Jain, V.; Yedle, A.; Maurya, T.; Yadav, A.; Puntambekar, A.; Goswami, S.G.; Choudhary, R.S.; Sandha, S.; Dwivedi, J.; Kane, G.V.; Mahawar, A.; Mohania, P.; Shrivastava, P.; Sharma, S.; Gupta, R.; Sharma, S.D.; Joshi, S.C.; Mistri, K.K.; Prakash, P.N.

    2013-01-01

    Raja Ramanna Centre for Advanced Technology has initiated the work on development of Superconducting Radio Frequency (SCRF) cavities and associated technologies as part of R and D activities for upcoming Spallation Neutron Source (SNS) project involving superconducting Linear Accelerator (LINAC). It is planned to use 650 MHz SCRF cavities for the medium and high energy section of the proposed LINAC. Under Indian Institution Fermilab Collaboration (IIFC), Raja Ramanna Centre for Advanced Technology is also working on development of 650 MHz (β=0.9) SCRF cavities proposed to be used in the high energy section of Project-X at FNAL. The work has been initiated with design and development of 650 MHz single cell SCRF cavity. FE analysis was done to estimate change in frequency with temperature as well as to estimate the frequency of the cavity at different cavity manufacturing stages. The development cycle comprises of design and manufacturing of forming tooling, machining, welding and RF measurement fixtures as well as design for manufacturing. The half-cell and beam tubes forming and machining of all parts were done using in-house facilities. The Electron beam welding was carried out at Inter-University Accelerator Centre (IUAC), New Delhi under a MoU. One 650 MHz single cell SCRF cavity has been recently manufactured. In this paper we present the development efforts on manufacturing and pre-qualification of 650 MHz (β=0.9) single cell SCRF cavity. (author)

  16. Optomechanic interactions in phoxonic cavities

    Bahram Djafari-Rouhani

    2014-12-01

    Full Text Available Phoxonic crystals are periodic structures exhibiting simultaneous phononic and photonic band gaps, thus allowing the confinement of both excitations in the same cavity. The phonon-photon interaction can be enhanced due to the overlap of both waves in the cavity. In this paper, we discuss some of our recent theoretical works on the strength of the optomechanic coupling, based on both photoelastic and moving interfaces mechanisms, in different (2D, slabs, strips phoxonic crystals cavities. The cases of two-dimensional infinite and slab structures will enable us to mention the important role of the symmetry and degeneracy of the modes, as well as the role of the materials whose photoelastic constants can be wavelength dependent. Depending on the phonon-photon pair, the photoelastic and moving interface mechanisms can contribute in phase or out-of-phase. Then, the main part of the paper will be devoted to the optomechanic interaction in a corrugated nanobeam waveguide exhibiting dual phononic/photonic band gaps. Such structures can provide photonic modes with very high quality factor, high frequency phononic modes of a few GHz inside a gap and optomechanical coupling rate reaching a few MHz.

  17. Development of superconducting acceleration cavity technology for free electron lasers

    Lee, Jong Min; Lee, Byung Cheol; Kim, Sun Kook; Jeong, Young Uk; Cho, Sung Oh

    2000-10-01

    As a result of the cooperative research between the KAERI and Peking University, the key technologies of superconducting acceleration cavity and photoelectron gun have been developed for the application to high power free electron lasers. A 1.5-GHz, 1-cell superconducting RF cavity has been designed and fabricated by using pure Nb sheets. The unloaded Q values of the fabricated superconducting cavity has been measured to be 2x10 9 at 2.5K, and 8x10 9 at 1.8K. The maximum acceleration gradient achieved was 12 MeV/m at 2.5K, and 20MV/m at 1.8 K. A cryostat for the 1-cell superconducting cavity has been designed. As a source of electron beam, a DC photocathode electron gun has been designed and fabricated, which is composed of a photocathode evaporation chamber and a 100-keV acceleration chamber. The efficiency of the Cs2Te photocathode is 3% nominally at room temperature, 10% at 290 deg C. The superconducting photoelectron gun system developed has been estimated to be a good source of high-brightness electron beam for high-power free electron lasers

  18. Development of superconducting acceleration cavity technology for free electron lasers

    Lee, Jong Min; Lee, Byung Cheol; Kim, Sun Kook; Jeong, Young Uk; Cho, Sung Oh

    2000-10-01

    As a result of the cooperative research between the KAERI and Peking University, the key technologies of superconducting acceleration cavity and photoelectron gun have been developed for the application to high power free electron lasers. A 1.5-GHz, 1-cell superconducting RF cavity has been designed and fabricated by using pure Nb sheets. The unloaded Q values of the fabricated superconducting cavity has been measured to be 2x10{sup 9} at 2.5K, and 8x10{sup 9} at 1.8K. The maximum acceleration gradient achieved was 12 MeV/m at 2.5K, and 20MV/m at 1.8 K. A cryostat for the 1-cell superconducting cavity has been designed. As a source of electron beam, a DC photocathode electron gun has been designed and fabricated, which is composed of a photocathode evaporation chamber and a 100-keV acceleration chamber. The efficiency of the Cs2Te photocathode is 3% nominally at room temperature, 10% at 290 deg C. The superconducting photoelectron gun system developed has been estimated to be a good source of high-brightness electron beam for high-power free electron lasers.

  19. Image transmission through a stable paraxial cavity

    Gigan, Sylvain; Lopez, Laurent; Treps, Nicolas; Maitre, Agnes; Fabre, Claude

    2005-01-01

    We study the transmission of a monochromatic 'image' through a paraxial cavity. Using the formalism of self-transform functions, we show that a transverse degenerate cavity transmits the self-transform part of the image, with respect to the field transformation over one round-trip of the cavity. This formalism gives insight into the understanding of the behavior of a transverse degenerate cavity, complementary to the transverse mode picture. An experiment of image transmission through a hemiconfocal cavity shows the interest of this approach

  20. Fast Ferroelectric L-Band Tuner for Superconducting Cavities

    Jay L. Hirshfield

    2012-07-03

    Design, analysis, and low-power tests are described on a ferroelectric tuner concept that could be used for controlling external coupling to RF cavities for the superconducting Energy Recovery Linac (ERL) in the electron cooler of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). The tuner configuration utilizes several small donut-shaped ferroelectric assemblies, which allow the design to be simpler and more flexible, as compared to previous designs. Design parameters for 704 and 1300 MHz versions of the tuner are given. Simulation results point to efficient performance that could reduce by a factor-of-ten the RF power levels required for driving superconducting cavities in the BNL ERL.