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Sample records for high performance cavity

  1. Performance of a high resolution cavity beam position monitor system

    Science.gov (United States)

    Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Pete; Frisch, Joe; Gronberg, Jeff; Hayano, Hitoshi; Honda, Yosuke; Kolomensky, Yury; Lyapin, Alexey; Malton, Stephen; May, Justin; McCormick, Douglas; Meller, Robert; Miller, David; Orimoto, Toyoko; Ross, Marc; Slater, Mark; Smith, Steve; Smith, Tonee; Terunuma, Nobuhiro; Thomson, Mark; Urakawa, Junji; Vogel, Vladimir; Ward, David; White, Glen

    2007-07-01

    It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than 1 nm. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 μrad over a dynamic range of approximately ±20 μm.

  2. Resolution of a High Performance Cavity Beam Position Monitor System

    International Nuclear Information System (INIS)

    Walston, S.; Chung, C.; Fitsos, P.; Gronberg, J.; Ross, M.; Khainovski, O.; Kolomensky, Y.; Loscutoff, P.; Slater, M.; Thomson, M.; Ward, D.; Boogert, S.; Vogel, V.; Meller, R.; Lyapin, A.; Malton, S.; Miller, D.; Frisch, J.; Hinton, S.; May, J.; McCormick, D.; Smith, S.; Smith, T.; White, G.; Orimoto, T.; Hayano, H.; Honda, Y.; Terunuma, N.; Urakawa, J.

    2005-01-01

    International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved - ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. A metrology system for the three BPMs was recently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame and has demonstrated that the three BPMs behave as a rigid-body to less than 5 nm. To date, we have demonstrated a BPM resolution of less than 20 nm over a dynamic range of +/- 20 microns

  3. Influence of Ta Content in High Purity Niobium on Cavity Performance Preliminary Results*

    CERN Document Server

    Kneisel, P

    2004-01-01

    In a previous paper* a program designed to study the influence of the residual tantalum content on the superconducting properties of pure niobium metal for RF cavities was outlined. The main rationale for this program was based on a potential cost reduction for high purity niobium, if a less strict limit on the chemical specification for Ta content, which is not significantly affecting the RRR–value, could be tolerated for high performance cavities. Four ingots with different Ta contents have been melted and transformed into sheets. In each manufacturing step the quality of the material has been monitored by employing chemical analysis, neutron activation analysis, thermal conductivity measurements and evaluation of the mechanical properties. The niobium sheets have been scanned for defects by an eddy current device. From three of the four ingots—Ta contents 100, 600 and 1,200 wppm—two single cell cavities each of the CEBAF variety have been fabricated and a series of tests on each ...

  4. Performance experience with the CEBAF SRF cavities

    International Nuclear Information System (INIS)

    Reece, C.; Benesch, J.; Drury, M.; Hovater, C.; Mammosser, J.; Preble, J.

    1995-01-01

    The full complement of 169 pairs of niobium superconducting cavities has been installed in the CEBAF accelerator. This paper surveys the performance characteristics of these cavities in vertical tests, commissioning in the tunnel, and operational experience to date. Although installed performance exceeds specifications, and 3.2 GeV beam has been delivered on target, present systems do not consistently preserve the high performance obtained in vertical dewar tests as operational capability. Principal sources of these limitations are discussed

  5. Improvement of cavity performance in the Saclay/Cornell/DESY's SC cavities

    International Nuclear Information System (INIS)

    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)

  6. Modeling and performance of the MHTGR [Modular High-Temperature Gas-Cooled Reactor] reactor cavity cooling system

    International Nuclear Information System (INIS)

    Conklin, J.C.

    1990-04-01

    The Reactor Cavity Cooling System (RCCS) of the Modular High- Temperature Gas-Cooled Reactor (MHTGR) proposed by the U.S. Department of Energy is designed to remove the nuclear afterheat passively in the event that neither the heat transport system nor the shutdown cooling circulator subsystem is available. A computer dynamic simulation for the physical and mathematical modeling of and RCCS is described here. Two conclusions can be made form computations performed under the assumption of a uniform reactor vessel temperature. First, the heat transferred across the annulus from the reactor vessel and then to ambient conditions is very dependent on the surface emissivities of the reactor vessel and RCCS panels. These emissivities should be periodically checked to ensure the safety function of the RCCS. Second, the heat transfer from the reactor vessel is reduced by a maximum of 10% by the presence of steam at 1 atm in the reactor cavity annulus for an assumed constant in the transmission of radiant energy across the annulus can be expected to result in an increase in the reactor vessel temperature for the MHTGR. Further investigation of participating radiation media, including small particles, in the reactor cavity annulus is warranted. 26 refs., 7 figs., 1 tab

  7. Superconducting niobium cavities with high gradients

    International Nuclear Information System (INIS)

    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

  8. A new measurement tool for characterization of superconducting rf accelerator cavities using high-performance LTS SQUIDs

    Energy Technology Data Exchange (ETDEWEB)

    Vodel, W [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Neubert, R [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Nietzsche, S [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Seidel, P [Friedrich-Schiller-University Jena, Helmholtzweg 5, 07743 Jena (Germany); Knaack, K [DESY Hamburg (Germany); Wittenburg, K [DESY Hamburg (Germany); Peters, A [Heidelberger Ionenstrahl-Therapiezentrum, Heidelberg (Germany)

    2007-11-15

    This paper presents a new system to measure very low currents in an accelerator environment, using a cryogenic current comparator (CCC). In principle a CCC is a conventional current transformer using the high-performance SQUID technology to sense the magnetic fields caused by the beam current. Since the system is sensitive on a pA level, it is an optimum device to detect dark currents of superconducting cavities. The system presented here is designed for the test facilities of the superconducting accelerator modules for the European XFEL at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg. Measurements in a quiet environment showed that an intrinsic noise level of the CCC of 40 pA Hz{sup -1/2} could be achieved.

  9. High performance Solid Rocket Motor (SRM) submerged nozzle/combustion cavity flowfield assessment

    Science.gov (United States)

    Freeman, J. A.; Chan, J. S.; Murph, J. E.; Xiques, K. E.

    1987-01-01

    Two and three dimensional internal flowfield solutions for critical points in the Space Shuttle solid rocket booster burn time were developed using the Lockheed Huntsville GIM/PAID Navier-Stokes solvers. These perfect gas, viscous solutions for the high performance motor characterize the flow in the aft segment and nozzle of the booster. Two dimensional axisymmetric solutions were developed at t = 20 and t = 85 sec motor burn times. The t = 85 sec solution indicates that the aft segment forward inhibitor stub produces vortices with are shed and convected downwards. A three dimensional 3.5 deg gimbaled nozzle flowfield solution was developed for the aft segment and nozzle at t = 9 sec motor burn time. This perfect gas, viscous analysis, provided a steady state solution for the core region and the flow through the nozzle, but indicated that unsteady flow exists in the region under the nozzle nose and near the flexible boot and nozzle/case joint. The flow in the nozzle/case joint region is characterized by low magnitude pressure waves which travel in the circumferential direction. From the two and three dimensional flowfield calculations presented it can be concluded that there is no evidence from these results that steady state gas dynamics is the primary mechanism resulting in the nozzle pocketing erosion experienced on SRM nozzles 8A or 17B. The steady state flowfield results indicate pocketing erosion is not directly initiated by a steady state gas dynamics phenomenon.

  10. High field conditioning of cryogenic RF cavities

    International Nuclear Information System (INIS)

    Cole, M.; Debiak, T.; Lom, C.; Shephard, W.; Sredniawski, J.

    1993-01-01

    Space-based and other related accelerators have conditioning and operation requirements that are not found in most machines. The use of cryogenic copper, relatively poor vacuum, and limited power storage and operating time put unusual demands on the high-field conditioning process and present some concerns. Two CW cryogenic engineering model open-quotes sparkerclose quotes cavities have been fabricated and tested to fairly high field levels. Tests included initial and repeated conditioning as well as sustained RF operations. The two cavities were an engineering model TDL and an engineering model RFQ. Both cavities operated at 425 MHz. The DTL was conditioned to 46 MV/m at 100% duty factor (CW) at cryogenic temperature. This corresponds to a gap voltage of 433 kV and a real estate accelerating gradient (energy gain/total cavity length) of 6.97 MV/m. The authors believe this to be record performance for cryo CW operation. During cryo pulsed operation, the same cavity reached 48 MV/m with 200 μsec pulses at 0.5% DF. The RFQ was conditioned to 30 MV/m CW at cryo, 85 kV gap voltage. During a brief period of cryo pulsed operation, the RFQ operated at 46 MV/m, or 125 kV gap voltage. Reconditioning experiments were performed on both cavities and no problems were encountered. It should be noted that the vacuum levels were not very stringent during these tests and no special cleanliness or handling procedures were followed. The results of these tests indicate that cavities can run CW without difficulty at cryogenic temperatures at normal conservative field levels. Higher field operation may well be possible, and if better vacuums are used and more attention is paid to cleanliness, much higher fields may be attainable

  11. Partial Cavity Flows at High Reynolds Numbers

    Science.gov (United States)

    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.

  12. Analysis of performance limitations for superconducting cavities

    International Nuclear Information System (INIS)

    J. R. Delayen; L. R. Doolittle; C. E. Reece

    1998-01-01

    The performance of superconducting cavities in accelerators can be limited by several factors, such as: field emission, quenches, arcing, rf power; and the maximum gradient at which a cavity can operate will be determined by the lowest of these limitations for that particular cavity. The CEBAF accelerator operates with over 300 cavities and, for each of them, the authors have determined the maximum operating gradient and its limiting factor. They have developed a model that allows them to determine the distribution of gradients that could be achieved for each of these limitations independently of the others. The result of this analysis can guide an R and D program to achieve the best overall performance improvement. The same model can be used to relate the performance of single-cell and multi-cell cavities

  13. Perturbed Partial Cavity Drag Reduction at High Reynolds Numbers

    Science.gov (United States)

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2010-11-01

    Ventilated partial cavities were investigated at Reynolds numbers to 80 million. These cavities could be suitable for friction drag reduction on ocean going vessels and thereby lead to environmental and economical benefits. The test model was a 3.05 m wide by 12.9 m long flat plate, with a 0.18 m backward-facing step and a cavity-terminating beach, which had an adjustable slope, tilt and height. The step and beach trapped a ventilated partial cavity over the longitudinal mid-section of the model. Large-scale flow perturbations, mimicking the effect of ambient ocean waves were investigated. For the conditions tested a cavity could be maintained under perturbed flow conditions when the gas flux supplied was greater than the minimum required to maintain a cavity under steady conditions, with larger perturbations requiring more excess gas flux to maintain the cavity. High-speed video was used to observe the unsteady three dimensional cavity closure, the overall cavity shape, and the cavity oscillations. Cavities with friction drag reduction exceeding 95% were attained at optimal conditions. A simplified energy cost-benefit analysis of partial cavity drag reduction was also performed. The results suggest that PCDR could potentially lead to energy savings.

  14. Recent Developments in SRF Cavity Science and Performance

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  16. The performance of gas storage cavities leached in salt

    International Nuclear Information System (INIS)

    Hugout, B.; Roger, C.

    1990-01-01

    Unlike other underground gas storage techniques, the gas storage cavities leached in salt and operated by compression-expansion are able to operate at high send-out rates with relatively small amounts of immobilized gas. The entire working gas capacity can be withdrawn within a period of between a few days and a few weeks, as opposed to several months for an aquifer or depleted field storage. To evaluate the deliverability of a cavity, which varies considerably during withdrawal, it is necessary to know at all times the gas pressure and temperature in the cavity and at all points in the production well and surface equipment, up to the point of injection into the network (manifold, filter, dehydration unit, meter run, and pressure governor). For this, a code (SITHERGAZ) based on the integration of thermodynamics and fluid mechanics equations was developed by Gaz be France. It has been operational since 1980. The experience acquired by Gaz de France in the operation of around twenty cavities, some of which have been in service for years, and the results of numerous simulations using the SITHERGAZ programme have made it possible to prove the legitimacy of a certain number of simplifying hypotheses. Using these hypotheses, the performance of cavities can be evaluated with reasonable accuracy by simple means. This paper describes the test procedures which provide a simple means to determine the flow pressure-loss coefficients and presents the practical calculation of cavity performance. (author). 5 figs

  17. The quest for high-gradient superconducting cavities

    International Nuclear Information System (INIS)

    Padamsee, H.

    1999-01-01

    Superconducting RF cavities excel in applications requiring continuous waves or long pulse voltages. Since power losses in the walls of the cavity increase as the square of the accelerating voltage, copper cavities become uneconomical as demand for high continuous wave voltage grows with particle energy. For these reasons, RF superconductivity has become an important technology for high energy and high luminosity accelerators. The state of art in performance of sheet metal niobium cavities is best represented by the statistics of more than 300 5-cell, 1.5-GHz cavities built for CEBAF. Key aspects responsible for the outstanding performance of the CEBAF cavities set are the anti-multipactor, elliptical cell shape, good fabrication and welding techniques, high thermal conductivity niobium, and clean surface preparation. On average, field emission starts at the electric field of 8.7 MV/m, but there is a large spread, even though the cavities received nominally the same surface treatment and assembly procedures. In some cavities, field emission was detected as low as 3 MV/m. In others, it was found to be as high as 19 MV/m. As we will discuss, the reason for the large spread in the gradients is the large spread in emitter characteristics and the random occurrence of emitters on the surface. One important phenomenon that limits the achievable RF magnetic field is thermal breakdown of superconductivity, originating at sub-millimeter-size regions of high RF loss, called defects. Simulation reveal that if the defect is a normal conducting region of 200 mm radius, it will break down at 5 MV/m. Producing high gradients and high Q in superconducting cavities demands excellent control of material properties and surface cleanliness. The spread in gradients that arises from the random occurrence of defects and emitters must be reduced. It will be important to improve installation procedures to preserve the excellent gradients now obtained in laboratory test in vertical cryostats

  18. Compact and highly efficient laser pump cavity

    Science.gov (United States)

    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.

  19. High Accelerating Field Superconducting Radio Frequency Cavities

    Science.gov (United States)

    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.

  20. Broadband Light Absorption and Efficient Charge Separation Using a Light Scattering Layer with Mixed Cavities for High-Performance Perovskite Photovoltaic Cells with Stability.

    Science.gov (United States)

    Moon, Byeong Cheul; Park, Jung Hyo; Lee, Dong Ki; Tsvetkov, Nikolai; Ock, Ilwoo; Choi, Kyung Min; Kang, Jeung Ku

    2017-08-01

    CH 3 NH 3 PbI 3 is one of the promising light sensitizers for perovskite photovoltaic cells, but a thick layer is required to enhance light absorption in the long-wavelength regime ranging from PbI 2 absorption edge (500 nm) to its optical band-gap edge (780 nm) in visible light. Meanwhile, the thick perovskite layer suppresses visible-light absorption in the short wavelengths below 500 nm and charge extraction capability of electron-hole pairs produced upon light absorption. Herein, we find that a new light scattering layer with the mixed cavities of sizes in 100 and 200 nm between transparent fluorine-doped tin oxide and mesoporous titanium dioxide electron transport layer enables full absorption of short-wavelength photons (λ cell with a light scattering layer of mixed cavities is stabilized due to suppressed charge accumulation. Consequently, this work provides a new route to realize broadband light harvesting of visible light for high-performance perovskite photovoltaic cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Analysis of the Qualification-Tests Performance of the Superconducting Cavities for the SNS Linac

    CERN Document Server

    Delayen, J R; Ozelis, O

    2004-01-01

    Thomas Jefferson National Accelerating Facility (Jefferson Lab) is producing superconducting radio frequency (SRF) cryomodules for the Spallation Neutron Source (SNS) cold linac. This consists of 11 medium-beta (β=0.61) cyomodules of 3 cavities each, and 12 high-beta (β=0.81) cryomodules of 4 cavities each. Before assembly into cavity strings the cavities undergo individual qualification tests in a vertical cryostat (VTA). In this paper we analyze the performance of the cavities during these qualification tests, and attempt to correlate this performance with cleaning, assembly, and testing procedures. We also compare VTA performance with performance in completed cryomodules.

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

    International Nuclear Information System (INIS)

    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

  3. Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by TEM and EELS

    OpenAIRE

    Trenikhina, Y.; Romanenko, A.; Kwon, J.; Zuo, J. -M.; Zasadzinski, J. F.

    2015-01-01

    Nanoscale defect structure within the magnetic penetration depth of ~100nm is key to the performance limitations of niobium superconducting radio frequency (SRF) cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride for...

  4. Study of superconducting cavities for high power proton accelerators

    International Nuclear Information System (INIS)

    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.)

  5. MEASUREMENT OF HIGH Q RF CAVITY IMPEDANCE WITH BEAM

    International Nuclear Information System (INIS)

    Limborg, Cecile

    2003-01-01

    An inexpensive method to measure, with beam, the Rs and Q of narrow-band high order resonances in RF cavities was developed on SPEAR. The two main results of this study are: (1) an improved operational stability of SPEAR; and (2) the decision to keep the present cavities for the proposed SPEAR upgrade. SPEAR3 will be run initially at 200 mA, twice the present current. Just beyond the current threshold, and before step loss, there is a regime in which the beam performs large amplitude, low frequency oscillations. Detailed measurements were performed to characterize the frequency, amplitude, growth and damping time of these relaxation oscillations

  6. Performance of TESLA Cavities After Fabrication and Preparation in Industry

    CERN Document Server

    Pekeler, Michael; Bauer, Stefan; Knobloch, Jens; Vom Stein, Peter

    2005-01-01

    In order to demonstrate cw operation of TESLA cavities in linear accelerators driving FEL applications, two TESLA cavities were manufactured and prepared by ACCEL for BESSY. After production, both cavities were prepared for vertical test at ACCEL's premises using state of the art chemical polishing and high pressure water rinsing techniques. The cavities were tested in DESY's vertical RF test installation. Accelerating gradients close to 25 MV/m were reached. One cavity was completed with a helium vessel modified for cw operation and prepared with chemical polishing, high pressure water rinsing, and assembled with the required High Power Coupler at ACCEL. The fully dressed cavity was then shipped under vacuum to BESSY and tested in the horizontal cryostat HoBiCaT. Horizontal RF test results will be presented and compared with the vertical test results.

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

    International Nuclear Information System (INIS)

    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.

  8. Performance of a reentrant cavity beam position monitor

    Directory of Open Access Journals (Sweden)

    Claire Simon

    2008-08-01

    Full Text Available The beam-based alignment and feedback systems, essential operations for the future colliders, require high resolution beam position monitors (BPMs. In the framework of the European CARE/SRF program, a reentrant cavity BPM with its associated electronics was developed by the CEA/DSM/Irfu in collaboration with DESY. The design, the fabrication, and the beam test of this monitor are detailed within this paper. This BPM is designed to be inserted in a cryomodule, work at cryogenic temperature in a clean environment. It has achieved a resolution better than 10  μm and has the possibility to perform bunch to bunch measurements for the x-ray free electron laser (X-FEL and the International Linear Collider (ILC. Its other features are a small size of the rf cavity, a large aperture (78 mm, and an excellent linearity. A first prototype of a reentrant cavity BPM was installed in the free electron laser in Hamburg (FLASH, at Deutsches Elektronen-Synchrotron (DESY and demonstrated its operation at cryogenic temperature inside a cryomodule. The second, installed, also, in the FLASH linac to be tested with beam, measured a resolution of approximately 4  μm over a dynamic range ±5  mm in single bunch.

  9. Performance of a reentrant cavity beam position monitor

    International Nuclear Information System (INIS)

    Simon, C.; Luong, M.; Chel, S.; Napoly, O.; Novo, J.; Roudier, D.; Rouviere, N.; Baboi, N.; Mildner, N.; Nolle, D.

    2008-01-01

    The beam-based alignment and feedback systems, essential operations for the future colliders, require high resolution beam position monitors (BPMs). In the framework of the European CARE/SRF program, a reentrant cavity BPM with its associated electronics was developed by the CEA/DSM/Irfu in collaboration with DESY. The design, the fabrication, and the beam test of this monitor are detailed within this paper. This BPM is designed to be inserted in a cryo-module, work at cryogenic temperature in a clean environment. It has achieved a resolution better than 10 μm and has the possibility to perform bunch to bunch measurements for the X-ray free electron laser (X-FEL) and the International Linear Collider (ILC). Its other features are a small size of the rf cavity, a large aperture (78 mm), and an excellent linearity. A first prototype of a reentrant cavity BPM was installed in the free electron laser in Hamburg (FLASH), at Deutsches Elektronen-Synchrotron (DESY) and demonstrated its operation at cryogenic temperature inside a cryo-module. The second, installed, also, in the FLASH linac to be tested with beam, measured a resolution of approximately 4 μm over a dynamic range ± 5 mm in single bunch. (authors)

  10. Performance of a reentrant cavity beam position monitor

    Science.gov (United States)

    Simon, Claire; Luong, Michel; Chel, Stéphane; Napoly, Olivier; Novo, Jorge; Roudier, Dominique; Rouvière, Nelly; Baboi, Nicoleta; Mildner, Nils; Nölle, Dirk

    2008-08-01

    The beam-based alignment and feedback systems, essential operations for the future colliders, require high resolution beam position monitors (BPMs). In the framework of the European CARE/SRF program, a reentrant cavity BPM with its associated electronics was developed by the CEA/DSM/Irfu in collaboration with DESY. The design, the fabrication, and the beam test of this monitor are detailed within this paper. This BPM is designed to be inserted in a cryomodule, work at cryogenic temperature in a clean environment. It has achieved a resolution better than 10μm and has the possibility to perform bunch to bunch measurements for the x-ray free electron laser (X-FEL) and the International Linear Collider (ILC). Its other features are a small size of the rf cavity, a large aperture (78 mm), and an excellent linearity. A first prototype of a reentrant cavity BPM was installed in the free electron laser in Hamburg (FLASH), at Deutsches Elektronen-Synchrotron (DESY) and demonstrated its operation at cryogenic temperature inside a cryomodule. The second, installed, also, in the FLASH linac to be tested with beam, measured a resolution of approximately 4μm over a dynamic range ±5mm in single bunch.

  11. Development of an advanced electropolishing setup for multicell high gradient niobium cavities

    Directory of Open Access Journals (Sweden)

    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.

  12. Performance of 3.9 GHz SRF cavities at Fermilab's ILCTA_MDB nhorizontal test stand

    Energy Technology Data Exchange (ETDEWEB)

    Harms, Elvin; Hocker, Andy; /Fermilab

    2008-08-01

    Fermilab is building a cryomodule containing four 3.9 GHz superconducting radio frequency (SRF) cavities for the Free electron LASer in Hamburg (FLASH) facility at the Deutsches Elektronen-SYnchrotron (DESY) laboratory. Before assembling the cavities into the cryomodule, each individual cavity is tested at Fermilab's Horizontal Test Stand (HTS). The HTS provides the capability to test fully-dressed SRF cavities at 1.8 K with high-power pulsed RF in order to verify that the cavities achieve performance requirements under these conditions. The performance at the HTS of the 3.9 GHz cavities built for FLASH is presented here.

  13. High power tests of dressed supconducting 1.3 GHz RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hocker, A.; Harms, E.R.; Lunin, A.; Sukhanov, A.; /Fermilab

    2011-03-01

    A single-cavity test cryostat is used to conduct pulsed high power RF tests of superconducting 1.3 GHz RF cavities at 2 K. The cavities under test are welded inside individual helium vessels and are outfitted ('dressed') with a fundamental power coupler, higher-order mode couplers, magnetic shielding, a blade tuner, and piezoelectric tuners. The cavity performance is evaluated in terms of accelerating gradient, unloaded quality factor, and field emission, and the functionality of the auxiliary components is verified. Test results from the first set of dressed cavities are presented here.

  14. Simulation of plasma loading of high-pressure RF cavities

    Science.gov (United States)

    Yu, K.; Samulyak, R.; Yonehara, K.; Freemire, B.

    2018-01-01

    Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have been performed in the range of parameters typical for practical muon cooling channels.

  15. Simulation of plasma loading of high-pressure RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Yu, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Initiative; Samulyak, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Computational Science Initiative; Stony Brook Univ., NY (United States). Dept. of Applied Mathematics and Statistics; Yonehara, K. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Freemire, B. [Northern Illinois Univ., DeKalb, IL (United States)

    2018-01-11

    Muon beam-induced plasma loading of radio-frequency (RF) cavities filled with high pressure hydrogen gas with 1% dry air dopant has been studied via numerical simulations. The electromagnetic code SPACE, that resolves relevant atomic physics processes, including ionization by the muon beam, electron attachment to dopant molecules, and electron-ion and ion-ion recombination, has been used. Simulations studies have also been performed in the range of parameters typical for practical muon cooling channels.

  16. High Pressure, High Gradient RF Cavities for Muon Beam Cooling

    CERN Document Server

    Johnson, R P

    2004-01-01

    High intensity, low emittance muon beams are needed for new applications such as muon colliders and neutrino factories based on muon storage rings. Ionization cooling, where muon energy is lost in a low-Z absorber and only the longitudinal component is regenerated using RF cavities, is presently the only known cooling technique that is fast enough to be effective in the short muon lifetime. RF cavities filled with high-pressure hydrogen gas bring two advantages to the ionization technique: the energy absorption and energy regeneration happen simultaneously rather than sequentially, and higher RF gradients and better cavity breakdown behavior are possible than in vacuum due to the Paschen effect. These advantages and some disadvantages and risks will be discussed along with a description of the present and desired RF R&D efforts needed to make accelerators and colliders based on muon beams less futuristic.

  17. Harmonic Cavity Performance for NSLS-II

    CERN Document Server

    Blednykh, Alexei; Podobedov, Boris; Rose, James; Towne, Nathan A; Wang, Jiunn-Ming

    2005-01-01

    NSLS-II is a 3 GeV ultra-high brightness storage ring that is planned to succeed the present NSLS rings at Brookhaven. Ultra-low emittance bunch combined with a short bunch length results in the Touschek lifetime of only a few hours, which strongly advocates including harmonic RF in the baseline design of NSLS-II. This paper describes the required harmonic RF parameters, trade-offs between the possible choices and the expected system performance, including the implications on lifetime and instabilities.

  18. High-Q superconducting niobium cavities for gravitational wave detectors

    International Nuclear Information System (INIS)

    De Paula, L A N; Furtado, S R; Aguiar, O D; N F Oliveira Jr, N F Oliveira Jr; Castro, P J; Barroso, J J

    2014-01-01

    The main purpose of this work is to optimize the electric Q-factor of superconducting niobium klystron cavities to be used in parametric transducers of the Mario Schenberg gravitational wave detector. Many cavities were manufactured from niobium with relatively high tantalum impurities (1420 ppm) and they were cryogenically tested to determine their resonance frequencies, unloaded electrical quality factors (Q 0 ) and electromagnetic couplings. These cavities were closed with a flat niobium plate with tantalum impurities below 1000 ppm and an unloaded electrical quality factors of the order of 10 5 have been obtained. AC conductivity of the order of 10 12 S/m has been found for niobium cavities when matching experimental results with computational simulations. These values for the Q-factor would allow the detector to reach the quantum limit of sensitivity of ∼ 10 −22 Hz −1/2 in the near future, making it possible to search for gravitational waves around 3.2 kHz. The experimental tests were performed at the laboratories of the National Institute for Space Research (INPE) and at the Institute for Advanced Studies (IEAv - CTA)

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

    Science.gov (United States)

    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.

  20. Role of thermal resistance on the performance of superconducting radio frequency cavities

    Science.gov (United States)

    Dhakal, Pashupati; Ciovati, Gianluigi; Myneni, Ganapati Rao

    2017-03-01

    Thermal stability is an important parameter for the operation of the superconducting radio frequency (SRF) cavities used in particle accelerators. The rf power dissipated on the inner surface of the cavities is conducted to the helium bath cooling the outer cavity surface and the equilibrium temperature of the inner surface depends on the thermal resistance. In this manuscript, we present the results of direct measurements of thermal resistance on 1.3 GHz single cell SRF cavities made from high purity large-grain and fine-grain niobium as well as their rf performance for different treatments applied to outer cavity surface in order to investigate the role of the Kapitza resistance to the overall thermal resistance and to the SRF cavity performance. The results show no significant impact of the thermal resistance to the SRF cavity performance after chemical polishing, mechanical polishing or anodization of the outer cavity surface. Temperature maps taken during the rf test show nonuniform heating of the surface at medium rf fields. Calculations of Q0(Bp) curves using the thermal feedback model show good agreement with experimental data at 2 and 1.8 K when a pair-braking term is included in the calculation of the Bardeen-Cooper-Schrieffer surface resistance. These results indicate local intrinsic nonlinearities of the surface resistance, rather than purely thermal effects, to be the main cause for the observed field dependence of Q0(Bp) .

  1. Role of thermal resistance on the performance of superconducting radio frequency cavities

    Directory of Open Access Journals (Sweden)

    Pashupati Dhakal

    2017-03-01

    Full Text Available Thermal stability is an important parameter for the operation of the superconducting radio frequency (SRF cavities used in particle accelerators. The rf power dissipated on the inner surface of the cavities is conducted to the helium bath cooling the outer cavity surface and the equilibrium temperature of the inner surface depends on the thermal resistance. In this manuscript, we present the results of direct measurements of thermal resistance on 1.3 GHz single cell SRF cavities made from high purity large-grain and fine-grain niobium as well as their rf performance for different treatments applied to outer cavity surface in order to investigate the role of the Kapitza resistance to the overall thermal resistance and to the SRF cavity performance. The results show no significant impact of the thermal resistance to the SRF cavity performance after chemical polishing, mechanical polishing or anodization of the outer cavity surface. Temperature maps taken during the rf test show nonuniform heating of the surface at medium rf fields. Calculations of Q_{0}(B_{p} curves using the thermal feedback model show good agreement with experimental data at 2 and 1.8 K when a pair-braking term is included in the calculation of the Bardeen-Cooper-Schrieffer surface resistance. These results indicate local intrinsic nonlinearities of the surface resistance, rather than purely thermal effects, to be the main cause for the observed field dependence of Q_{0}(B_{p}.

  2. Efficient quality-eactor estimation of a vertical cavity employing a high-contrast grating

    DEFF Research Database (Denmark)

    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....

  3. Superconducting spoke cavities for high-velocity applications

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. High pressure discharges in cavities formed by microfabrication techniques

    International Nuclear Information System (INIS)

    Khan, B.A.; Cammack, D.A.; Pinker, R.D.; Racz, J.

    1997-01-01

    High pressure discharges are the basis of small high intensity light sources. In this work, we demonstrate the formation of high pressure discharges, in cavities formed by applying micromachining and integrated circuit techniques to quartz substrates. Cavities containing varying amounts of mercury and argon were fabricated to obtain high pressure discharges. A high pressure mercury discharge was formed in the electrodeless cavities by exciting them with a microwave source, operating at 2.45 GHz and in the electroded cavities by applying a dc voltage. The contraction of the discharge into a high pressure arc was observed. A broad emission spectrum due to self-absorption and collisions between excited atoms and normal atoms, typical of high pressure mercury discharges, was measured. The light output and efficacy increased with increasing pressure. The measured voltage was used to estimate the pressure within the electroded cavities, which is as high as 127 atm for one of the two cavities discussed in this work. Efficacies over 40 lumens per watt were obtained for the electrodeless cavities and over 50 scr(l)m/W for the electroded cavities. copyright 1997 American Institute of Physics

  5. High-R Walls for Remodeling: Wall Cavity Moisture Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Wiehagen, J.; Kochkin, V.

    2012-12-01

    The focus of the study is on the performance of wall systems, and in particular, the moisture characteristics inside the wall cavity and in the wood sheathing. Furthermore, while this research will initially address new home construction, the goal is to address potential moisture issues in wall cavities of existing homes when insulation and air sealing improvements are made.

  6. High-R Walls for Remodeling. Wall Cavity Moisture Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Wiehagen, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Kochkin, V. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2012-12-01

    The focus of the study is on the performance of wall systems, and in particular, the moisture characteristics inside the wall cavity and in the wood sheathing. Furthermore, while this research will initially address new home construction, the goal is to address potential moisture issues in wall cavities of existing homes when insulation and air sealing improvements are made.

  7. Thermal resistances of air in cavity walls and their effect upon the thermal insulation performance

    Energy Technology Data Exchange (ETDEWEB)

    Bekkouche, S.M.A.; Cherier, M.K.; Hamdani, M.; Benamrane, N. [Application of Renewable Energies in Arid and Semi Arid Environments /Applied Research Unit on Renewable Energies/ EPST Development Center of Renewable Energies, URAER and B.P. 88, ZI, Gart Taam Ghardaia (Algeria); Benouaz, T. [University of Tlemcen, BP. 119, Tlemcen R.p. 13000 (Algeria); Yaiche, M.R. [Development Center of Renewable Energies, CDER and B.P 62, 16340, Route de l' Observatoire, Bouzareah, Algiers (Algeria)

    2013-07-01

    The optimum thickness in cavity walls in buildings is determined under steady conditions; the heat transfer has been calculated according to ISO 15099:2003. Two forms of masonry units are investigated to conclude the advantage of high thermal emissivity. The paper presents also some results from a study of the thermal insulation performance of air cavities bounded by thin reflective material layer 'eta = 0.05'. The results show that the most economical cavity configuration depends on the thermal emissivity and the insulation material used.

  8. Modeling high-power RF accelerator cavities with SPICE

    International Nuclear Information System (INIS)

    Humphries, S. Jr.

    1992-01-01

    The dynamical interactions between RF accelerator cavities and high-power beams can be treated on personal computers using a lumped circuit element model and the SPICE circuit analysis code. Applications include studies of wake potentials, two-beam accelerators, microwave sources, and transverse mode damping. This report describes the construction of analogs for TM mn0 modes and the creation of SPICE input for cylindrical cavities. The models were used to study continuous generation of kA electron beam pulses from a vacuum cavity driven by a high-power RF source

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

    Science.gov (United States)

    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.

  10. Physical and mechanical metallurgy of high purity Nb for accelerator cavities

    International Nuclear Information System (INIS)

    Bieler, T.R.; Wright, N.T.; Pourboghrat, F.; Compton, C.; Hartwig, K.T.; Baars, D.; Zamiri, A.; Chandrasekaran, S.; Darbandi, P.; Jiang, H.; Skoug, E.; Balachandran, S.; Ice, G.E.; Liu, W.

    2010-01-01

    In the past decade, high Q values have been achieved in high purity Nb superconducting radio frequency (SRF) cavities. Fundamental understanding of the physical metallurgy of Nb that enables these achievements is beginning to reveal what challenges remain to establish reproducible and cost-effective production of high performance SRF cavities. Recent studies of dislocation substructure development and effects of recrystallization arising from welding and heat treatments and their correlations with cavity performance are considered. With better fundamental understanding of the effects of dislocation substructure evolution and recrystallization on electron and phonon conduction, as well as the interior and surface states, it will be possible to design optimal processing paths for cost-effective performance using approaches such as hydroforming, which minimizes or eliminates welds in a cavity.

  11. Physical and mechanical metallurgy of high purity Nb for accelerator cavities

    Directory of Open Access Journals (Sweden)

    T. R. Bieler

    2010-03-01

    Full Text Available In the past decade, high Q values have been achieved in high purity Nb superconducting radio frequency (SRF cavities. Fundamental understanding of the physical metallurgy of Nb that enables these achievements is beginning to reveal what challenges remain to establish reproducible and cost-effective production of high performance SRF cavities. Recent studies of dislocation substructure development and effects of recrystallization arising from welding and heat treatments and their correlations with cavity performance are considered. With better fundamental understanding of the effects of dislocation substructure evolution and recrystallization on electron and phonon conduction, as well as the interior and surface states, it will be possible to design optimal processing paths for cost-effective performance using approaches such as hydroforming, which minimizes or eliminates welds in a cavity.

  12. Performance of Superconducting Cavities as Required for the SPL

    CERN Document Server

    Weingarten, Wolfgang

    2008-01-01

    This document outlines an optimisation analysis for the RF cavities of the planned Superconducting Proton Linac (SPL) at CERN with regard to the operating frequency and temperature. The analysis is based on a phenomenological assessment of the field dependent Q-value, as taken from published test results from RF cavities of various proveniences. It turns out that the design Q-value at an accelerating gradient of 25 MV/m ($\\Beta$ = 1 cavity) of $1^{.}10^{10}$ at 704 (1408) MHz is attainable at 1.9 (1.6) K, respectively, however, with the present state-of-the-art manufacturing, at the expense of some reprocessing. The optimum of the total electrical grid power consumption (composed of RF and cryogenics) is estimated as a function of frequency and operating temperature for both the low and high power SPL. This document outlines an optimisation analysis for the RF cavities of the planned Superconducting Proton Linac (SPL) at CERN with regard to the operating frequency and temperature. The analysis is based on a p...

  13. High power RF test of an 805 MHz RF cavity for a muon cooling channel

    International Nuclear Information System (INIS)

    Li, Derun; Corlett, J.; MacGill, R.; Rimmer, R.; Wallig, J.; Zisman, M.; Moretti, A.; Qian, Z.; Wu, V.; Summers, D.; Norem, J.

    2002-01-01

    We present recent high power RF test results on an 805 MHz cavity for a muon cooling experiment at Lab G in Fermilab. In order to achieve high accelerating gradient for large transverse emittance muon beams, the cavity design has adopted a pillbox like shape with 16 cm diameter beam iris covered by thin Be windows, which are demountable to allow for RF tests of different windows. The cavity body is made from copper with stiff stainless steel rings brazed to the cavity body for window attachments. View ports and RF probes are available for visual inspections of the surface of windows and cavity and measurement of the field gradient. Maximum of three thermo-couples can be attached to the windows for monitoring the temperature gradient on the windows caused by RF heating. The cavity was measured to have Q 0 of about 15,000 with copper windows and coupling constant of 1.3 before final assembling. A 12 MW peak power klystron is available at Lab G in Fermilab for the high power test. The cavity and coupler designs were performed using the MAFIA code in the frequency and the time domain. Numerical simulation results and cold test measurements on the cavity and coupler will be presented for comparisons

  14. RECENT DEVELOPMENTS IN SRF CAVITY SCIENCE AND PERFORMANCE

    International Nuclear Information System (INIS)

    Gianluigi Ciovati

    2006-01-01

    A recipe based on centrifugal barrel polishing (CBP) and electropolishing (EP), applied on newly designed single-cells, led to the achievement of B p values close to the thermodynamic critical field of Nb and to new records in terms of accelerating gradients The fabrication of cavities made of large-grain Nb is emerging as a viable option to reduce the material cost without sacrificing the performance. The Q-drop is not caused exclusively by losses at grain boundaries in Nb. Baking is the only known remedy against the Q-drop and its effect seems to be related to a change of the properties of the Nb up to a depth of about 20 nm. 120 C is the optimum temperature and the baking time can be reduced to 12 h. Cleaning techniques such as high-pressure rinse (HPR) are being studied in detail in order to be optimized for mass-production. Dry-ice cleaning may become a complementary cleaning method. Work is being done to better understand and to improve the EP process

  15. Status and first measurement results for a high gradient CH-cavity

    Energy Technology Data Exchange (ETDEWEB)

    Almomani, Ali; Ratzinger, Ulrich [Institut fuer Angewandte Physik, Frankfurt Universitaet, Frankfurt am Main (Germany)

    2016-07-01

    This pulsed linac activity aims on compact designs and on a considerable increase of the voltage gain per meter. A high gradient CH {sup *} cavity operated at 325 MHz was developed at IAP {sup *} Frankfurt. The mean effective accelerating field for this cavity is expected well above 10 MV/m at β=0.164. This cavity is developed within a funded project. The results might influence the rebuilt of the UNILAC {sup *} Alvarez section, aiming to achieve the beam intensities specified for the GSI {sup *} FAIR project (15 mA U28+). Another motivation is the development of an efficient pulsed ion accelerator for significantly higher energies like 60 AMeV. The new GSI 3 MW Thales klystron test stand will be used for the cavity RF power tests. Detailed studies on two different types of copper plating will be performed with this cavity.

  16. High-Q perpendicular-biased ferrite-tuned cavity

    International Nuclear Information System (INIS)

    Carlini, R.D.; Thiessen, H.A.; Potter, J.M.

    1983-01-01

    Rapid-cycling proton synchrotrons, such as the proposed LAMPF II accelerator, require approximately 10 MV per turn rf with 17% tuning range near 50 MHz. The traditional approach to ferrite-tuned cavities uses a ferrite which is longitudinally biased (rf magnetic field parallel to bias field). This method leads to unacceptably high losses in the ferrite. At Los Alamos, we are developing a cavity with transverse bias (rf magnetic field perpendicular to the bias field) that makes use of the tensor permeability of the ferrite. Modest power tests of a small (10-cm-dia) quarter-wave singly re-entrant cavity tuned by nickel-zinc ferrites and aluminum-doped garnets indicate that the losses in the ferrite can be made negligible compared with the losses due to the surface resistivity of the copper cavity at power levels from 2 to 200 watts

  17. Coherent stacking of picosecond laser pulses in a high-Q optical cavity for accelerator applications

    International Nuclear Information System (INIS)

    Androsov, V.P.; Karnaukhov, I.M.; Telegin, Yu.N.

    2007-01-01

    We have performed the harmonic analysis of the steady-state coherent pulse-stacking process in a high-Q Fabry-Perot cavity. The expression for the stacked pulse shape is obtained as a function of both the laser cavity and pulse-stacking cavity parameters. We have also estimated the pulse power gains attainable in the laser-optical system of NESTOR storage ring, which is under development at Kharkov Institute of Physics and Technology. It is shown that high power gains (∼10 4 ) can be, in principle, achieved in a cavity, formed with low-absorption, high reflectivity (R ∼ 0.9999) mirrors, if the laser cavity length will differ exactly by half wavelength from the pulse-stacking cavity length. It implies development of the sophisticated frequency stabilization loop for maintaining the cavity length constant within a sub-nanometer range. At the same time, power gains of ∼10 3 can be obtained with medium reflectivity mirrors (R ∼ 0.999) at considerably lower cost

  18. High-repetition intra-cavity source of Compton radiation

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    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.

  20. Cavity Control and Cooling of Nanoparticles in High Vacuum

    Science.gov (United States)

    Millen, James

    2016-05-01

    Levitated systems are a fascinating addition to the world of optically-controlled mechanical resonators. It is predicted that nanoparticles can be cooled to their c.o.m. ground state via the interaction with an optical cavity. By freeing the oscillator from clamping forces dissipation and decoherence is greatly reduced, leading to the potential to produce long-lived, macroscopically spread, mechanical quantum states, allowing tests of collapse models and any mass limit of quantum physics. Reaching the low pressures required to cavity-cool to the ground state has proved challenging. Our approach is to cavity cool a beam of nanoparticles in high vacuum. We can cool the c.o.m. motion of nanospheres, and control the rotation of nanorods, with the potential to produce cold, aligned nanostructures. Looking forward, we will utilize novel microcavities to enhance optomechanical cooling, preparing particles in a coherent beam ideally suited to ultra-high mass interferometry at 107 a.m.u.

  1. Development of high pressure rinsing set up for 650 MHz, 5- cell superconducting RF cavity cleaning

    International Nuclear Information System (INIS)

    Suhane, S.K.; Chauhan, S.K.; Bose, A.; Kokil, S.V.; Rajput, D.S.; Oraon, B.; Md Hussain; Sahu, A.; Raghavendra, S.; Joshi, S.C.

    2015-01-01

    High pressure rinsing (HPR) is an ultra-cleanliness process for the surface preparation of high field superconducting RF cavities. Any dust particle or chemical residue on the interior of cavity causes field emission. Jets of high pressure (80-100 bar) ultra pure water dislodge surface contaminants that normally resist removal with conventional rinsing procedures, leading to substantial reduction in field emission and better cavity performance. For cleaning of 650 MHz, 5-cell SRF cavities, a high pressure rinsing set up has been developed at RRCAT. The HPR tool has a rotating wand coaxial with the vertically mounted SRF cavity that is moving up and down. Fan style spray nozzles are attached to the end of the rotating wand and the water jets emerging from spray nozzles scan the entire internal surface of the cavity. The set-up was installed in a specially built clean area meeting cleanliness class 100 standards. The ultrapure water with resistivity 2 ≥ 18 MΩ-cm required for rinsing is obtained from a dedicated water purification system installed for this purpose. The paper describes the salient design and constructional details of the high pressure rinsing set up. Characterization of water jet parameters based on the momentum transfer between the water jet and a load cell is also presented. (author)

  2. Macroscopic quantum electrodynamics of high-Q cavities

    International Nuclear Information System (INIS)

    Khanbekyan, Mikayel

    2009-01-01

    In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the possible

  3. Macroscopic quantum electrodynamics of high-Q cavities

    Energy Technology Data Exchange (ETDEWEB)

    Khanbekyan, Mikayel

    2009-10-27

    In this thesis macroscopic quantum electrodynamics in linear media was applied in order to develop an universally valid quantum theory for the description of the interaction of the electromagnetic field with atomic sources in high-Q cavities. In this theory a complete description of the characteristics of the emitted radiation is given. The theory allows to show the limits of the applicability of the usually applied theory. In order to establish an as possible generally valid theory first the atom-field interaction was studied in the framework of macroscopic quantum electrodynamics in dispersive and absorptive media. In order to describe the electromagnetic field from Maxwell's equations was started, whereby the noise-current densities, which are connected with the absorption of the medium, were included. The solution of these equations expresses the electromagnetic field variables by the noise-current densities by means of Green's tensor of the macroscopic Maxwell equations. The explicit quantization is performed by means of the noise-current densities, whereby a diagonal Hamiltonian is introduced, which then guarantees the time development according to Maxwell's equation and the fulfillment of the fundamental simultaneous commutation relations of the field variables. In the case of the interaction of the medium-supported field with atoms the Hamiltonian must be extended by atom-field interactions energies, whereby the canonical coupling schemes of the minimal or multipolar coupling can be used. The dieelectric properties of the material bodies as well as their shape are coded in the Green tensor of the macroscopic Maxwell equations. As preparing step first the Green tensor was specified in order to derive three-dimensional input-output relations for the electromagnetic field operators on a plane multilayer structure. Such a general dewscription of the electromagnetic field allows the inclusion both of dispersion and absorption of the media and the

  4. A High Current Proton Linac with 352 MHz SC Cavities

    CERN Document Server

    Pagani, C; Pierini, P

    1996-01-01

    A proposal for a 10-120 mA proton linac employing superconducting beta-graded, CERN type, four cell cavities at 352 MHz is presented. The high energy part (100 MeV-1 GeV) of the machine is split in three beta-graded sections, and transverse focusing is provided via a periodic doublet array. All the parameters, like power in the couplers and accelerating fields in the cavities, are within the state of the art, achieved in operating machines. A first stage of operation at 30 mA beam current is proposed, while the upgrade of the machine to 120 mA operation can be obtained increasing the number of klystrons and couplers per cavity. The additional coupler ports, up to four, will be integrated in the cavity design. Preliminary calculations indicate that beam transport is feasible, given the wide aperture of the 352 MHz structures. A capital cost of less than 100 M$ at 10 mA, reaching up to 280 M$ for the 120 mA extension, has been estimated for the superconducting high energy section (100 MeV-1 GeV). The high effic...

  5. Performance analysis of progressive cavity pumps in oil wells with high BSW (Basic Sediment Water); Analise do desempenho de elastometros do bombeio de cavidades progressivas em pocos de petroleo com elavado BSW (Basic Sediment Water)

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Cindi Alves; Santos, Joao Paulo Lobo dos; Lobato, Ana Katerine de Carvalho Lima; Santos, Luiz Carlos Lobato dos [Universidade Federal da Bahia, BA (Brazil); Duarte, Lindemberg de Jesus Nogueira [Universidade Federal do Rio Grande do Norte, RN (Brazil)

    2012-07-01

    One of the most important equipment in the progressing cavity pump (PCP) is the subsurface pump, which comprises a rotor and a stator covered internally by an elastomer. This is responsible for sealing the pump and, consequently, for elevating the fluids. In fact, this polymer is used because of the ability to generate pressure in the pump by the seals formed between the cavities. In order to guarantee that the elastomer will have a good performance in the PCP system certain requirements need to be checked, such as: stress, elongation, hardness, resilience, permeability and adhesion. The fluids and solids handled by the PCP system, allied to high temperatures can cause premature wear in the elastomers. The most common reactions which are also observed in most of the wells are swelling, shrinkage, softening, hardening and explosive decompression. In this sense, the aim of this work is to study some elastomers which were chosen based on compatibility tests conducted by a major oil company. The problems that occurred in the wells will be analyzed in order to verify whether the choice of the elastomer had some influence on system failure. For this purpose, the intervention reports, efficiency tests and failure analysis reports will be used. At the end of this work, it was possible to diagnose the causes, consequences and solutions to inherent problems at various oil wells in a field that is in an advanced stage of recovery. Finally, it was concluded that simple changes in the process of compatibility analysis would help to increase the reliability level of the tests, especially the problems observed during the PCP operation in hostile environments. (author)

  6. High field tests of 1.3 GHz niobium superconducting cavities

    International Nuclear Information System (INIS)

    Kako, Eiji; Noguchi, Shuichi; Ono, Masaaki

    1993-01-01

    Four single-cell cavities prepared by various surface treatments have been tested repeatedly since 1991. A maximum accelerating gradient of 25.1 MV/m with a high Q 0 value of ∼10 10 was successfully achieved after heat treatment at 1400degC. A temperature mapping system with a high thermal sensitivity under superfluid helium was developed to understand phenomena limiting a maximum accelerating gradient. The cavity performances and the phenomena at high fields are reported in this paper. (author)

  7. Application of the guided lock technique to Advanced Virgo's high-finesse cavities using reduced actuation

    Science.gov (United States)

    Bersanetti, Diego

    2018-02-01

    The recent upgrades of the Advanced Virgo experiment required an update of the locking strategy for the long, high-finesse arm cavities of the detector. In this work we will present a full description of the requirements and the constraints of such system in relation to the lock acquisition of the cavities; the focus of this work is the strategy used to accomplish this goal, which is the adaptation and use of the guided lock technique, which dynamically slows down a suspended optical cavity in order to make the lock possible. This work describes the first application of such locking technique to 3km long optical cavities, which are affected by stringent constraints as the low force available on the actuators, the high finesse and the maximum sustainable speed of the cavities, which is quite low due to a number of technical reasons that will be explained. A full set of optical time domain simulations has been developed in order to study the feasibility and the performance of this algorithm and will be throughout discussed, while finally the application on the real Advanced Virgo's arm cavities will be reported.

  8. [The oral cavity condition in patients with high blood pressure].

    Science.gov (United States)

    Rosiak, Joanna; Kubić-Filiks, Beata; Szymańska, Jolanta

    2015-10-01

    The incidence of high blood pressure in adults is estimated at ca. 30-40% of the general population. Both hypertension disease and hypertensive drugs affect the condition of the patients' oral cavity. A review of the current literature shows that disorders most frequently found in the masticatory organ of patients with hypertension include: xerostomia, changes in salivary glands, gum hypertrophy, lichenoid lesions, taste disorders, and paraesthesias. The authors emphasize that patients with high blood pressure, along with the treatment of the underlying disease, should receive prophylactic and therapeutic dental care. This would enable reduction and/or elimination of unpleasant complaints, and also help prevent the emergence of secondary disorders in the patients' oral cavity as a result of hypertension pharmacotherapy. © 2015 MEDPRESS.

  9. Development of high purity niobium material for superconducting cavities

    International Nuclear Information System (INIS)

    Umezawa, Hiroaki; Takeuchi, Koichi; Sakita, Kohei; Suzuki, Takafusa; Saito, Kenji; Noguchi, Shuichi.

    1993-01-01

    For the superconducting niobium cavities, issues of thermal quench and field emission have to be solved to achieve a high field gradient (>25MV/m) for TESLA (TeV Energy Superconducting Linear Accelerator). In order to overcome the quench, upgrading of thermal conductivity of niobium material at the low temperature is very important. On the reduction of the field emission not only dust particles but also defect, impurity and inhomogeneity should be considered. Therefore development of high purity niobium material is very important to solve these issues. This paper describes the our latest R and D for high purity niobium material. (author)

  10. accelerating cavity

    CERN Multimedia

    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.

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

    International Nuclear Information System (INIS)

    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

  12. High-Q, high gradient niobium-coated cavities at CERN

    CERN Document Server

    Calatroni, Sergio; Darriulat, Pierre; Peck, M A; Valente, A M; Van't Hof, C A

    1999-01-01

    Superconducting cavities made by sputter-deposition of a thin niobium film onto copper have proven over the years to be a viable alternative to bulk niobium, the best example being the very successful operation of LEP at 200 GeV. It will be shown that this technology, investigated at 1.5 GHz by a dedicated R&D effort at CERN, can be developed to unprecedented performance, proving that no fundamental limitation prevents high quality factors to be maintained over a broad range of accelerating field.

  13. Numerical and Experimental Study of the Q Factor of High-Q Micropillar Cavities

    DEFF Research Database (Denmark)

    Gregersen, Niels; Reitzenstein, S.; Kistner, C.

    2010-01-01

    Micropillar cavities are potential candidates for high-efficiency single-photon sources and are testbeds for cavity quantum electrodynamics experiments. In both applications a high quality (Q) factor is desired. It was recently shown that the Q of high-Q semiconductor micropillar cavities exhibit...

  14. New Methods for Thin Film Deposition and First Investigations of the use of High Temperature Superconductors for Thin Film Cavities

    CERN Document Server

    Gustafsson, Anna; Vollenberg, Wilhelmus; Seviour, Rebecca

    2010-01-01

    Niobium thin film cavities have shown good and reliable performance for LEP and LHC, although there are limitations to overcome if this technique should be used for new accelerators such as the ILC. New coating techniques like High Power Impulse Magnetron Sputtering (HiPIMS) has shown very promising results and we will report on its possible improvements for Nb thin film cavity performance. Current materials used in accelerator Superconducting Radio Frequency (SRF) technologies operate at temperatures below 4 K, which require complex cryogenic systems. Researchers have investigated the use of High Temperature Superconductors (HTS) to form RF cavities, with limited success. We propose a new approach to achieve a high-temperature SRF cavity based on the superconducting ’proximity effect’. The superconducting proximity effect is the effect through which a superconducting material in close proximity to a non-superconducting material induces a superconducting condensate in the latter. Using this effect we hope...

  15. Three-Dimensional Electromagnetic High Frequency Axisymmetric Cavity Scars.

    Energy Technology Data Exchange (ETDEWEB)

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt

    2014-10-01

    This report examines the localization of high frequency electromagnetic fi elds in three-dimensional axisymmetric cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This report treats both the case where the opposing sides, or mirrors, are convex, where there are no interior foci, and the case where they are concave, leading to interior foci. The scalar problem is treated fi rst but the approximations required to treat the vector fi eld components are also examined. Particular att ention is focused on the normalization through the electromagnetic energy theorem. Both projections of the fi eld along the scarred orbit as well as point statistics are examined. Statistical comparisons are m ade with a numerical calculation of the scars run with an axisymmetric simulation. This axisymmetric cas eformstheoppositeextreme(wherethetwomirror radii at each end of the ray orbit are equal) from the two -dimensional solution examined previously (where one mirror radius is vastly di ff erent from the other). The enhancement of the fi eldontheorbitaxiscanbe larger here than in the two-dimensional case. Intentionally Left Blank

  16. Evidence of high-field radio-frequency hot spots due to trapped vortices in niobium cavities

    Directory of Open Access Journals (Sweden)

    G. Ciovati

    2008-12-01

    Full Text Available Superconducting radio-frequency (rf cavities made of high-purity niobium exhibit strong anomalous rf losses starting at peak surface magnetic fields of about 90–100 mT in the gigahertz range. This phenomenon is referred to as “Q drop.” Temperature maps of the cavity surface have revealed the presence of “hot spots” in the high magnetic field region of the cavities. Several models have been proposed over the years to explain this phenomenon but there is still no experimental evidence on the mechanisms behind such hot spots. In this work we show that at least some of the hot spots are due to trapped vortices responsible for the anomalous losses. Here we report experiments in which a local thermal gradient was applied to the hot spot regions of a cavity in order to displace the vortices. Temperature maps measured before and after applying the thermal gradient unambiguously show that the hot spots do move and change their intensities, allowing us to determine changes in the hot spot positions and strengths and their effect on the cavity performance. Results on a large-grain niobium cavity clearly show a different distribution and in some cases a weakening of the intensity of the “hot spots,” suggesting new ways of improving the cavity performance without additional material treatments.

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

    International Nuclear Information System (INIS)

    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).

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

    Science.gov (United States)

    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).

  19. Development of high gradient superconducting radio frequency cavities for international linear collider and energy recovery linear accelerator

    International Nuclear Information System (INIS)

    Saito, Kenji; Furuta, Fumio; Saeki, Takayuki

    2009-01-01

    Superconducting radio frequency (SRF) cavities were used for storage rings like TRISTAN at KEK, HERA at DESY and LEP-II at CERN in 1990-2000. This technology has been accepted as a common accelerator technology. In August 2004, ITPR recommended an electron/positron linear collider based on SRF technology for the future high energy physics. ICFA accepted the recommendation and named it ILC (International Linear Collider). SRF cavities have a very unique feature due to its very small surface resistance. Energy recovery is another very exciting application. Many laboratories are proposing ERL (Energy Recovery LINAC) as a next bright photon source. In these accelerators, production of SRF cavities with reliably high performance is the most important issue. In this paper the activities of ILC high gradient cavities will be introduced. ERL activity will be briefly presented. (author)

  20. Development of High Gradient Superconducting Radio Frequency Cavities for International Linear Collider and Energy Recovery Linear Accelerator

    Science.gov (United States)

    Saito, Kenji; Furuta, Fumio; Saeki, Takayuki

    Superconducting radio frequency (SRF) cavities were used for storage rings like TRISTAN at KEK, HERA at DESY and LEP-II at CERN in 1990-2000. This technology has been accepted as a common accelerator technology. In August 2004, ITPR recommended an electron/positron linear collider based on SRF technology for the future high energy physics. ICFA accepted the recommendation and named it ILC (International Linear Collider). SRF cavities have a very unique feature due to its very small surface resistance. Energy recovery is another very exciting application. Many laboratories are proposing ERL (Energy Recovery LINAC) as a next bright photon source. In these accelerators, production of SRF cavities with reliably high performance is the most important issue. In this paper the activities of ILC high gradient cavities will be introduced. ERL activity will be briefly presented.

  1. Status and outlook for high power processing of 1.3 GHz TESLA multicell cavities

    International Nuclear Information System (INIS)

    Kirchgessner, J.; Barnes, P.; Graber, J.; Metzger, D.; Mofat, D.; Muller, H.; Padamsee, H.; Sears, J.; Tigner, M.; Matheisen, A.

    1993-01-01

    In order to increase the usable accelerating gradient in Superconducting TESLA cavities, the field emission threshold barrier must be raised. As has been previously demonstrated on S-band cavities, a way to accomplish this is with the use of high peak power RF processing. A transmitter with a peak power of 2 Mwatt and 300 μsec pulse length has been assembled and has been used to process TESLA cavities. Several five cell TESLA cavities at 1.3 GHz have been manufactured for this purpose. This transmitter and the cavities will be described and the results of the tests will be presented

  2. Performance of the AC perpendicular biased ferrite tuned cavity for the TRIUMF KAON factory booster synchrotron

    International Nuclear Information System (INIS)

    Poirier, R.L.; Enchevich, I.B.; Mitra, A.K.; Fong, K.; Blaker, G.C.; Fang, S.

    1992-11-01

    The rf cavity for the Booster Synchrotron requires a frequency swing from 46 Mhz to 61 Mhz at a repetition rate of 50 Hz and a maximum accelerating voltage of 62.5 kV. These requirements were achieved on the prototype ferrite tuned cavity[1] for a short period of time and without any fast rf feedback or cavity tuning loops. Initially fast rf feedback and cavity tuning loops were closed at fixed frequencies (ferrite tuner dc biased ) to measure some of the response characteristics of the amplifier-cavity chain. Then a major effort was put into measuring the bandwidth response of the tuner in order to design the rf control loops for ac bias operation at 50 Hz. The performance of these control loops and results from long term running of the rf system are reported. (author) 3 refs., 5 figs

  3. High-power tests of a single-cell copper accelerating cavity driven by two input couplers

    International Nuclear Information System (INIS)

    Horan, D.; Bromberek, D.; Meyer, D.; Waldschmidt, G.

    2008-01-01

    High-power tests were conducted on a 350-MHz, single-cell copper accelerating cavity driven simultaneously by two H-loop input couplers for the purpose of determining the reliability, performance, and power-handling capability of the cavity and related components, which have routinely operated at 100-kW power levels. The test was carried out utilizing the APS 350-MHz RF Test Stand, which was modified to split the input rf power into two frac12-power feeds, each supplying power to a separate H-loop coupler on the cavity. Electromagnetic simulations of the two-coupler feed system were used to determine coupler match, peak cavity fields, and the effect of phasing errors between the coupler feed lines. The test was conducted up to a maximum total rf input power of 164-kW CW. Test apparatus details and performance data will be presented.

  4. High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities.

    Science.gov (United States)

    Zhang, Xiangao; Shao, Mingzhen; Zeng, Xiaoqi

    2016-10-18

    In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly. Furthermore, by modulating the geometrical parameters appropriately, Fano resonances with high sensitivities to the changes in refractive index can be realized. A maximum figure of merit (FoM) value of 74.3 is obtained. Considerable applications for this work can be found in bio/chemical sensors with excellent performance and other nanophotonic integrated circuit devices such as optical filters, switches and modulators.

  5. Technologies and R&D for a High Resolution Cavity BPM for the CLIC Main Beam

    CERN Document Server

    Towler, J R; Soby, L; Wendt, M; Boogert, S T; Cullinan, F J; Lyapin, A

    2013-01-01

    The Main Beam (MB) linac of the Compact Linear Collider (CLIC) requires a beam orbit measurement system with high spatial (50 nm) and high temporal resolution (50 ns) to resolve the beam position within the 156 ns long bunch train, traveling on an energy-chirped, minimum dispersive trajectory. A 15 GHz prototype cavity BPM has been commissioned in the probe beam-line of the CTF3 CLIC Test Facility. We discuss performance and technical details of this prototype installation, including the 15 GHz analogue downconverter, the data acquisition and the control electronics and software. An R&D outlook is given for the next steps, which requires a system of 3 cavity BPMs to investigate the full resolution potential.

  6. High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities

    Directory of Open Access Journals (Sweden)

    Xiangao Zhang

    2016-10-01

    Full Text Available In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances increase accordingly. Furthermore, by modulating the geometrical parameters appropriately, Fano resonances with high sensitivities to the changes in refractive index can be realized. A maximum figure of merit (FoM value of 74.3 is obtained. Considerable applications for this work can be found in bio/chemical sensors with excellent performance and other nanophotonic integrated circuit devices such as optical filters, switches and modulators.

  7. Active material, optical mode and cavity impact on nanoscale electro-optic modulation performance

    Science.gov (United States)

    Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

    2017-10-01

    Electro-optic modulation is a key function in optical data communication and possible future optical compute engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While a variety of high-performance modulators have been demonstrated, no comprehensive picture of what factors are most responsible for high performance has emerged so far. Here we report the first systematic and comprehensive analytical and computational investigation for high-performance compact on-chip electro-optic modulators by considering emerging active materials, model considerations and cavity feedback at the nanoscale. We discover that the delicate interplay between the material characteristics and the optical mode properties plays a key role in defining the modulator performance. Based on physical tradeoffs between index modulation, loss, optical confinement factors and slow-light effects, we find that there exist combinations of bias, material and optical mode that yield efficient phase or amplitude modulation with acceptable insertion loss. Furthermore, we show how material properties in the epsilon near zero regime enable reduction of length by as much as by 15 times. Lastly, we introduce and apply a cavity-based electro-optic modulator figure of merit, Δλ/Δα, relating obtainable resonance tuning via phase shifting relative to the incurred losses due to the fundamental Kramers-Kronig relations suggesting optimized device operating regions with optimized modulation-to-loss tradeoffs. This work paves the way for a holistic design rule of electro-optic modulators for high-density on-chip integration.

  8. Effect of low temperature baking in nitrogen on the performance of a niobium superconducting radio frequency cavity

    OpenAIRE

    Pashupati Dhakal; Santosh Chetri; Shreyas Balachandran; Peter J. Lee; Gianluigi Ciovati

    2018-01-01

    We report the rf performance of a single cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of 120–160 °C with a nitrogen partial pressure of ∼25  m Torr. This increase in quality factor as well as the Q-rise phenomenon (anti-Q-slope) is similar to those previously obtained with high temperature nitrogen doping as well as titanium...

  9. Effect of Low Temperature Baking in Nitrogen on the Performance of a Niobium Superconducting Radio Frequency Cavity

    OpenAIRE

    Dhakal, Pashupati; Chetri, Santosh; Balachandran, Shreyas; Lee, Peter J.; Ciovati, Gianluigi

    2017-01-01

    We report the rf performance of a single-cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of 120-160 {\\deg}C with a nitrogen partial pressure of ~25 mTorr. This increase in quality factor as well as the Q-rise phenomenon (anti-Q-slope) is similar to those previously obtained with high temperature nitrogen doping as well as titan...

  10. Measuring the performance of the coaxial HOM coupler on a 2-cell TESLA-shape copper cavity

    International Nuclear Information System (INIS)

    Wang Fang; Wang Erdong; Zhang Baocheng; Zhao Kui

    2009-01-01

    Coaxial High Order Mode (HOM) couplers have been fabricated at Peking University and their RF performance has been measured on a test device consisting of a coaxial transmission line and a 2-cell TESLA-shape copper cavity. The test results on the 2-cell TESLA-shape copper cavity with HOM couplers indicate that the coupler can cut off the fundamental mode TM 010 and absorb HOMs effectively after a careful adjustment. The optimal angle of the HOM coupler with the beam tube is found. The initial test results of HOM couplers are presented in this paper. (authors)

  11. Proof-of-principle demonstration of Nb3Sn superconducting radiofrequency cavities for high Q0 applications

    Science.gov (United States)

    Posen, S.; Liepe, M.; Hall, D. L.

    2015-02-01

    Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb3Sn. In this paper, we present results for single cell cavities coated with Nb3Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q0 out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q0 at quench of 8 × 109. In each case, the peak surface magnetic field at quench was well above Hc1, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q0 values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb3Sn cavities in future applications.

  12. Performance in the vertical test of the 832 nine-cell 1.3 GHz cavities for the European X-ray Free Electron Laser

    Science.gov (United States)

    Reschke, D.; Gubarev, V.; Schaffran, J.; Steder, L.; Walker, N.; Wenskat, M.; Monaco, L.

    2017-04-01

    The successful production and associated vertical testing of over 800 superconducting 1.3 GHz accelerating cavities for the European X-ray Free Electron Laser (XFEL) represents the culmination of over 20 years of superconducting radio-frequency R&D. The cavity production took place at two industrial vendors under the shared responsibility of INFN Milano-LASA and DESY. Average vertical testing rates at DESY exceeded 10 cavities per week, peaking at up to 15 cavities per week. The cavities sent for cryomodule assembly at Commissariat à l'énergie atomique (CEA) Saclay achieved an average maximum gradient of approximately 33 MV /m , reducing to ˜30 MV /m when the operational specifications on quality factor (Q) and field emission were included (the so-called usable gradient). Only 16% of the cavities required an additional surface retreatment to recover their low performance (usable gradient less than 20 MV /m ). These cavities were predominantly limited by excessive field emission for which a simple high pressure water rinse (HPR) was sufficient. Approximately 16% of the cavities also received an additional HPR, e.g. due to vacuum problems before or during the tests or other reasons, but these were not directly related to gradient performance. The in-depth statistical analyses presented in this report have revealed several features of the series produced cavities.

  13. Performance in the vertical test of the 832 nine-cell 1.3 GHz cavities for the European X-ray Free Electron Laser

    Directory of Open Access Journals (Sweden)

    D. Reschke

    2017-04-01

    Full Text Available The successful production and associated vertical testing of over 800 superconducting 1.3 GHz accelerating cavities for the European X-ray Free Electron Laser (XFEL represents the culmination of over 20 years of superconducting radio-frequency R&D. The cavity production took place at two industrial vendors under the shared responsibility of INFN Milano–LASA and DESY. Average vertical testing rates at DESY exceeded 10 cavities per week, peaking at up to 15 cavities per week. The cavities sent for cryomodule assembly at Commissariat à l’énergie atomique (CEA Saclay achieved an average maximum gradient of approximately 33  MV/m, reducing to ∼30  MV/m when the operational specifications on quality factor (Q and field emission were included (the so-called usable gradient. Only 16% of the cavities required an additional surface retreatment to recover their low performance (usable gradient less than 20  MV/m. These cavities were predominantly limited by excessive field emission for which a simple high pressure water rinse (HPR was sufficient. Approximately 16% of the cavities also received an additional HPR, e.g. due to vacuum problems before or during the tests or other reasons, but these were not directly related to gradient performance. The in-depth statistical analyses presented in this report have revealed several features of the series produced cavities.

  14. New results of development on high efficiency high gradient superconducting rf cavities

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Li, Z. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hao, Z. K. [Peking Univ., Beijing (China); Liu, K. X. [Peking Univ., Beijing (China); Zhao, H. Y. [OTIC, Ningxia (China); Adolphsen, C. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-09-01

    We report on the latest results of development on high-efficiency high-gradient superconducting radio frequency (SRF) cavities. Several 1-cell cavities made of large-grain niobium (Nb) were built, processed and tested. Two of these cavities are of the Low Surface Field (LSF) shape. Series of tests were carried out following controlled thermal cycling. Experiments toward zero-field cooling were carried out. The best experimentally achieved results are Eacc = 41 MV/m at Q0 = 6.5×1010 at 1.4 K by a 1-cell 1.3 GHz large-grain Nb TTF shape cavity and Eacc = 49 MV/m at Q0 = 1.5×1010 at 1.8 K by a 1-cell 1.5 GHz large-grain Nb CEBAF upgrade low-loss shape cavity.

  15. Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator

    International Nuclear Information System (INIS)

    Souli, M.

    2007-07-01

    The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q c in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing

  16. Improvement of the operational performance of SRF cavities via in situ helium processing and waveguide vacuum processing

    International Nuclear Information System (INIS)

    Reece, C.E.; Drury, M.; Rao, M.G.; Nguyen-Tuong, V.

    1997-01-01

    The useful performance range of the superconducting rf (SRF) cavities in the CEBAF accelerator at Jefferson Lab is frequently limited by electron field emission and derived phenomena. Improvements are required to support future operation of the accelerator at higher than 5 GeV. Twelve operational cryomodules have been successfully processed to higher useful operating gradients via rf-helium processing. Progress against field emission was evidenced by improved high-field Q, reduced x-ray production and greatly reduced incidence of arcing at the cold ceramic window. There was no difficulty reestablishing beamline vacuum following the processing. Cavities previously limited to 4-6 MV/m are now operating stably at 6-9 MV/m. By applying a pulsed-rf processing technique, we have also improved the pressure stability of the thermal transition region of the input waveguide for several cavities

  17. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    Science.gov (United States)

    Pipino, Andrew Charles Rule

    1999-11-16

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  18. High sensitive photonic crystal multiplexed biosensor array using H0 sandwiched cavities

    Directory of Open Access Journals (Sweden)

    Arafa Safia

    2017-01-01

    Full Text Available We theoretically investigate a high sensitive photonic crystal integrated biosensor array structure which is potentially used for label-free multiplexed sensing. The proposed device consists of an array of three sandwiched H0 cavities patterned above silicon on insulator (SOI substrate; each cavity has been designed for different cavity spacing and different resonant wavelength. Results obtained by performing finite-difference time-domain (FDTD simulations, indicate that the response of each detection unit shifts independently in terms of refractive index variations. The optimized design makes possible the combination of sensing as a function of location, as well as a function of time in the same platform. A refractive index sensitivity of 520nm/RIU and a quality factor over 104 are both achieved with an accompanied crosstalk of less than -26 dB. In addition, the device presents an improved detection limit (DL of 1.24.10-6 RIU and a wide measurement range. These features make the designed device a promising element for performing label-free multiplexed detection in monolithic substrate for medical diagnostics and environmental monitoring.

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

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

    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....

  1. High order mode damping in a pill box cavity

    International Nuclear Information System (INIS)

    Voelker, F.; Lambertson, G.; Rimmer, R.

    1991-04-01

    We have substantially damped the higher order modes (HOM's) in a pill box cavity with attached beam pipe, while reducing the Q of the principal mode by less that 10%. This was accomplished by cutting slots in the cavity end wall at a radius at which the magnetic field of the lowest frequency HOM's is large. The slots couple energy from the cavity into waveguides which are below cut off for the principal mode, but which propagate energy at the HOM frequencies. Three slots 120 degrees apart couple HOM energy to three waveguides. We are concerned primarily with accelerating and deflecting modes: i.e. the TM mnp modes of order m=0 and m=1. For the strongest damping, only three m=0 and m=1 modes were detectable. These were the principal TM 010 mode, the TM 011 longitudinal mode, and the TM 110 deflecting mode. In addition the HOM Q's and the reduction of Q for the principal mode were determined by computer calculation. The principal mode Q for an actual rf cavity could not be measured because the bolted joints used in the construction of the cavity were not sufficiently good to support Q's above 6000. The measured Q of the first longitudinal mode was 31 and of the first transverse mode 37. Our maximum damping was limited by how well we could terminated the waveguides, and indeed, the computer calculations for the TM 011 and TM 110 modes give values in the range we measured. 2 refs., 2 figs

  2. Very high repetition-rate electro-optical cavity-dumped Nd: YVO4 laser with optics and dynamics stabilities

    Science.gov (United States)

    Liu, Xuesong; Shi, Zhaohui; Huang, Yutao; Fan, Zhongwei; Yu, Jin; Zhang, Jing; Hou, Liqun

    2015-02-01

    In this paper, a very high repetition-rate, short-pulse, electro-optical cavity-dumped Nd: YVO4 laser is experimentally and theoretically investigated. The laser performance is optimized from two aspects. Firstly, the laser resonator is designed for a good thermal stability under large pump power fluctuation through optics methods. Secondly, dynamics simulation as well as experiments verifies that cavity dumping at very high repetition rate has better stability than medium/high repetition rate. At 30 W, 880 nm pump power, up to 500 kHz, constant 5 ns, stable 1064 nm fundamental-mode laser pulses can be obtained with 10 W average output power.

  3. Performance of Ferrite Vector Modulators in the LLRF System of the Fermilab HINS 6-Cavity Test

    Energy Technology Data Exchange (ETDEWEB)

    Varghese, Philip [Fermilab; Barnes, Barry [Fermilab; Chase, Brian [Fermilab; Cullerton, Ed [Fermilab; Tan, Cong [Fermilab

    2013-04-01

    The High Intensity Neutrino Source (HINS) 6-cavity test is a part of the Fermilab HINS Linac R&D program for a low energy, high intensity proton Hsup>- linear accelerator. One of the objectives of the 6-cavity test is to demonstrate the use of high power RF Ferrite Vector Modulators(FVM) for independent control of multiple cavities driven by a single klystron. The beamline includes an RFQ and six cavities. The LLRF system provides a primary feedback loop around the RFQ and the distribution of the regulated klystron output is controlled by secondary learning feed-forward loops on the FVMs for each of the six cavities. The feed-forward loops provide pulse to pulse correction to the current waveform profiles of the FVM power supplies to compensate for beam-loading and other disturbances. The learning feed-forward loops are shown to successfully control the amplitude and phase settings for the cavities well within the 1 % and 1 degree requirements specified for the system.

  4. High-Q silicon-on-insulator slot photonic crystal cavity infiltrated by a liquid

    International Nuclear Information System (INIS)

    Caër, Charles; Le Roux, Xavier; Cassan, Eric

    2013-01-01

    We report the experimental realization of a high-Q slot photonic crystal cavity in Silicon-On-Insulator (SOI) configuration infiltrated by a liquid. Loaded Q-factor of 23 000 is measured at telecom wavelength. The intrinsic quality factor inferred from the transmission spectrum is higher than 200 000, which represents a record value for slot photonic crystal cavities on SOI, whereas the maximum of intensity of the cavity is roughly equal to 20% of the light transmitted in the waveguide. This result makes filled slot photonic crystal cavities very promising for silicon-based light emission and ultrafast nonlinear optics

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

    DEFF Research Database (Denmark)

    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....

  6. Stable and High OSNR Compound Linear-Cavity Single-Longitudinal-Mode Erbium-Doped Silica Fiber Laser Based on an Asymmetric Four-Cavity Structure

    International Nuclear Information System (INIS)

    Feng Ting; Yan Feng-Ping; Li Qi; Peng Wan-Jing; Feng Su-Chun; Wen Xiao-Dong; Tan Si-Yu; Liu Peng

    2012-01-01

    We propose a stable and high optical signal-to-noise ratio (OSNR) compound linear-cavity single-longitudinal-mode (SLM) erbium-doped silica fiber laser. It consists of three uniform fiber Bragg gratings (FBGs) and two fiber couplers to form a simple asymmetric four-cavity structure to select the longitudinal mode. The stable SLM operation at the wavelength of 1544.053 nm with a 3 dB bandwidth of 0.014 nm and an OSNR of ∼60 dB was verified experimentally. Under laboratory conditions, a power fluctuation performance of less than 0.05 dB for 5 h and wavelength variation of less than 0.01 nm for about 150 min is demonstrated. Finally, the characteristic of laser output power as a function of pump power is investigated. The proposed system provides a simple and cost-effective approach to realize a stable SLM fiber laser

  7. Endodontic treatment of dens evaginatus by performing a splint guided access cavity.

    Science.gov (United States)

    Mena-Álvarez, Jesús; Rico-Romano, Cristina; Lobo-Galindo, Ana Belén; Zubizarreta-Macho, Álvaro

    2017-11-12

    Dens evaginatus (DE) is described as an unusual dental malformation. Tooth structure variations attached to this anatomical disturbance complicates the performance of a conservative access cavity for a conventional root canal treatment. Author's purpose is to describe the treatment of a type V DE by using splits as guides to perform access cavity. This clinical case shows a root canal treatment of a type V DE diagnosed by using a cone beam computed tomography (CBCT). Access cavity was planned through an osseointegrated implant planning software and guided by a stereolithographied split. After endodontic treatment, tooth was sculpted for placing a veneer, processed by a chair-side system in a single session. CBCT is an effective method for obtaining internal anatomical information of teeth with anatomical malformations. The osseointegrated implant planning software is an effective method for planning root canal treatment and designing stereolithograped splits (for performing minimally invasive access cavities). Stereolithographed splints allow performing a guided and conservative access cavity of teeth affected by dental malformations whereas digital technology allows us to esthetically reconstruct a tooth in a single session. © 2017 Wiley Periodicals, Inc.

  8. High-Q cavity-induced synchronization in oscillator arrays

    DEFF Research Database (Denmark)

    Filatrella, Giovanni; Pedersen, Niels Falsig; Wiesenfeld, Kurt

    2000-01-01

    A model for a large number of Josephson junctions coupled to a cavity is presented. The system displays synchronization behavior very similar to that reported in recent experiments [P. Barbara ct al., Phys. Rev. Lett. 82, 1963 (1999)]. The essential dynamical mechanism responsible for coherence...

  9. Effect of high solenoidal magnetic fields on breakdown voltages of high vacuum 805 MHz cavities

    International Nuclear Information System (INIS)

    Moretti, A.; Bross, A.; Geer, S.; Qian, Z.; Norem, J.; Li, D.; Zisman, M.; Torun, Y.; Rimmer, R.; Errede, D.

    2005-01-01

    There is an on going international collaboration studying the feasibility and cost of building a muon collider or neutrino factory [1,2]. An important aspect of this study is the full understanding of ionization cooling of muons by many orders of magnitude for the collider case. An important muon ionization cooling experiment, MICE [3], has been proposed to demonstrate and validate the technology that could be used for cooling. Ionization cooling is accomplished by passing a high-emittance muon beam alternately through regions of low Z material, such as liquid hydrogen, and very high accelerating RF Cavities within a multi-Tesla solenoidal field. To determine the effect of very large solenoidal magnetic fields on the generation of dark current, x-rays and on the breakdown voltage gradients of vacuum RF cavities, a test facility has been established at Fermilab in Lab G. This facility consists of a 12 MW 805 MHz RF station and a large warm bore 5 T solenoidal superconducting magnet containing a pill box type cavity with thin removable window apertures. This system allows dark current and breakdown studies of different window configurations and materials. The results of this study will be presented. The study has shown that the peak achievable accelerating gradient is reduced by a factor greater than 2 when solenoidal field of greater than 2 T are applied to the cavity

  10. Two-dimensional Josephson junction arrays coupled through a high-Q cavity

    DEFF Research Database (Denmark)

    Filatrella, G.; Pedersen, Niels Falsig; Wiesenfeld, K.

    2001-01-01

    the cavity. The highly resonant cavity induces synchronized behavior, which is qualitatively different than what is familiar from other studies on nonlinear oscillator arrays, for example the Kuramoto model. We also address the effects of disorder, as well as the role of detuning between the spontaneous...

  11. Numerical survey of pressure wave propagation around and inside an underground cavity with high order FEM

    Science.gov (United States)

    Esterhazy, Sofi; Schneider, Felix; Schöberl, Joachim; Perugia, Ilaria; Bokelmann, Götz

    2016-04-01

    The research on purely numerical methods for modeling seismic waves has been more and more intensified over last decades. This development is mainly driven by the fact that on the one hand for subsurface models of interest in exploration and global seismology exact analytic solutions do not exist, but, on the other hand, retrieving full seismic waveforms is important to get insides into spectral characteristics and for the interpretation of seismic phases and amplitudes. Furthermore, the computational potential has dramatically increased in the recent past such that it became worthwhile to perform computations for large-scale problems as those arising in the field of computational seismology. Algorithms based on the Finite Element Method (FEM) are becoming increasingly popular for the propagation of acoustic and elastic waves in geophysical models as they provide more geometrical flexibility in terms of complexity as well as heterogeneity of the materials. In particular, we want to demonstrate the benefit of high-order FEMs as they also provide a better control on the accuracy. Our computations are done with the parallel Finite Element Library NGSOLVE ontop of the automatic 2D/3D mesh generator NETGEN (http://sourceforge.net/projects/ngsolve/). Further we are interested in the generation of synthetic seismograms including direct, refracted and converted waves in correlation to the presence of an underground cavity and the detailed simulation of the comprehensive wave field inside and around such a cavity that would have been created by a nuclear explosion. The motivation of this application comes from the need to find evidence of a nuclear test as they are forbidden by the Comprehensive Nuclear-Test Ban Treaty (CTBT). With this approach it is possible for us to investigate the wave field over a large bandwidth of wave numbers. This again will help to provide a better understanding on the characteristic signatures of an underground cavity, improve the protocols for

  12. Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by transmission electron microscopy and electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Trenikhina, Y., E-mail: yuliatr@fnal.gov [Physics Department, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Romanenko, A., E-mail: aroman@fnal.gov [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Kwon, J.; Zuo, J.-M. [Materials Science and Engineering Department, University of Illinois, Urbana, Illinois 61801 (United States); Zasadzinski, J. F. [Physics Department, Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

    2015-04-21

    Nanoscale defect structure within the magnetic penetration depth of ∼100 nm is key to the performance limitations of niobium superconducting radio frequency cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120 °C baking. Furthermore, we demonstrate that adding 800 °C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120 °C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120 °C bake.

  13. Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by transmission electron microscopy and electron energy loss spectroscopy

    Science.gov (United States)

    Trenikhina, Y.; Romanenko, A.; Kwon, J.; Zuo, J.-M.; Zasadzinski, J. F.

    2015-04-01

    Nanoscale defect structure within the magnetic penetration depth of ˜100 nm is key to the performance limitations of niobium superconducting radio frequency cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120 °C baking. Furthermore, we demonstrate that adding 800 °C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120 °C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120 °C bake.

  14. Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by transmission electron microscopy and electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Trenikhina, Y.; Romanenko, A.; Kwon, J.; Zuo, J.-M.; Zasadzinski, J. F.

    2015-01-01

    Nanoscale defect structure within the magnetic penetration depth of ~100 nm is key to the performance limitations of niobium superconducting radio frequency cavities. Using a unique combination of advanced thermometry during cavity RF measurements, and TEM structural and compositional characterization of the samples extracted from cavity walls, we discover the existence of nanoscale hydrides in electropolished cavities limited by the high field Q slope, and show the decreased hydride formation in the electropolished cavity after 120°C baking. Furthermore, we demonstrate that adding 800°C hydrogen degassing followed by light buffered chemical polishing restores the hydride formation to the pre-120°C bake level. We also show absence of niobium oxides along the grain boundaries and the modifications of the surface oxide upon 120°C bake

  15. Improved Sound Absorption Performance of Nonwoven Fabric using Fabric Facing and Air Back Cavity

    Directory of Open Access Journals (Sweden)

    Ismail Ahmad Yusuf

    2017-01-01

    Full Text Available This paper presents the improvement methods to increase sound absorption performance of polyethylene based nonwoven fabric (PNF. The methods are placing a woven fabric in front of the sample as well as providing air cavity behind the sample. The samples were experimentally tested in an impedance tube based on ISO 10354-2:2001 whereby two microphones are used and the transfer matrix methods are employed. From the results, it can be seen that placing front woven fabric effectively increases sound absorption performance. Moreover, introducing air cavity gap behind the sample is also found to be more significant to increase sound absorption.

  16. Operation of a high-gradient superconducting radio-frequency cavity with a non-evaporable getter pump

    International Nuclear Information System (INIS)

    Ciovati, G.; Geng, R.; Lushtak, Y.; Manini, P.; Maccallini, E.; Stutzman, M.

    2017-01-01

    The use of non-evaporable getter (NEG) pumps in particle accelerators has increased significantly over the past few years because of their large pumping speed, particularly for hydrogen, compared to the size of the pump. A concern about using such pumps in superconducting radio-frequency (SRF) accelerators is the possibility of shedding particulates which could then migrate into the SRF cavities and produce field emission, therefore degrading the cavity performance. One option to mitigate such issue is to use sintered getter materials which intrinsically offer superior mechanical and particle retention properties. In this article we present the results from cryogenic RF tests of a high-gradient SRF cavity after being evacuated several times with an NEG pump equipped with sintered getter disks and placed in close proximity to the cavity. The results showed that the cavity performance was not affected by the pump up to the quench gradient of 34 MV/m. As a result of this study, two such NEG pumps have been installed next to a cryomodule in the CEBAF accelerator to maintain ultra-high vacuum in the SRF cryomodule and two adjacent warm girder sections.

  17. Operation of a high-gradient superconducting radio-frequency cavity with a non-evaporable getter pump

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, G., E-mail: gciovati@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Geng, R. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Lushtak, Y.; Manini, P.; Maccallini, E. [SAES Getters, S.p.A, Viale Italia, 77, 20020 Lainate, MI (Italy); Stutzman, M. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

    2017-01-11

    The use of non-evaporable getter (NEG) pumps in particle accelerators has increased significantly over the past few years because of their large pumping speed, particularly for hydrogen, compared to the size of the pump. A concern about using such pumps in superconducting radio-frequency (SRF) accelerators is the possibility of shedding particulates which could then migrate into the SRF cavities and produce field emission, therefore degrading the cavity performance. One option to mitigate such issue is to use sintered getter materials which intrinsically offer superior mechanical and particle retention properties. In this article we present the results from cryogenic RF tests of a high-gradient SRF cavity after being evacuated several times with an NEG pump equipped with sintered getter disks and placed in close proximity to the cavity. The results showed that the cavity performance was not affected by the pump up to the quench gradient of 34 MV/m. As a result of this study, two such NEG pumps have been installed next to a cryomodule in the CEBAF accelerator to maintain ultra-high vacuum in the SRF cryomodule and two adjacent warm girder sections.

  18. A free-jet experimental study on the performance of a cavity-type ramjet

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Jianguo; Pan, Yu; Liang, Jianhan; Wang, Zhenguo [National University of Defense Technology, ChangSha (China)

    2011-11-15

    Free jet experiments have been conducted to evaluate the performance of a cavity-type ramjet. To prevent uncertainty of combustion parameters, a method to calculate internal thrust from cold flow parameters is brought forward. According to this analysis method, the internal thrust of the cavity-type ramjet increases linearly with the stoichiometric ratio while the specific impulse decreases squarely. The aero-propulsive balance of a conceptive missile is also examined, focusing on the effect of attack angle. Considering both efficiency and performance, an attack angle of 3{approx}6 degrees is recommended. And the free-jet experimental results show that the cavity-type ramjet can supply sufficient thrust for the missile under cruise conditions.

  19. High current electron beam acceleration in dielectric-filled RF cavities

    International Nuclear Information System (INIS)

    Faehl, R.J.; Keinigs, R.K.

    1996-01-01

    The acceleration of charged particles in radio frequency (RF) cavities is a widely used mode in high energy accelerators. Advantages include very high accelerating gradients and very stable phase control. A traditional limitation for such acceleration has been their use for intense, high current beam generation. This constraint arises from the inability to store a large amount of electromagnetic energy in the cavity and from loading effects of the beam on the cavity. The authors have studied a simple modification to transcend these limitations. Following Humphries and Huang, they have conducted analytic and numerical investigations of RF accelerator cavities in which a high dielectric constant material, such as water, replaces most of the cavity volume. This raises the stored energy in a cavity of given dimensions by a factor var-epsilon/var-epsilon 0 . For a water fill, var-epsilon/var-epsilon 0 ∼ 80, depending on the frequency. This introduction of high dielectric constant material into the cavity reduces the resonant frequencies by a factor of (var-epsilon/var-epsilon 0 ) 1/2 . This reduced operating frequency mans that existing high efficiency power supplies, at lower frequencies, can be used for an accelerator

  20. Operating experience with high beta superconducting RF cavities

    International Nuclear Information System (INIS)

    Dylla, H.F.; Doolittle, L.R.; Benesch, J.F.

    1993-01-01

    The number of installed and operational β=1 superconducting rf cavities has grown significantly over the last two years in accelerator laboratories in Europe, Japan and the U.S. The total installed acceleration capability as of mid-1993 is approximately 1 GeV at nominal gradients. Major installations at CERN, DESY, KEK and CEBAF have provided large increments to the installed base and valuable operational experience. A selection of test data and operational experience gathered to date is reviewed

  1. Operating experience with high beta superconducting rf cavities

    International Nuclear Information System (INIS)

    Dylla, H.F.; Doolittle, L.R.; Benesch, J.F.

    1993-06-01

    The number of installed and operational β = 1 superconducting rf cavities has grown significantly over the last two years in accelerator laboratories in Europe, Japan and the US. The total installed acceleration capability as of mid-1993 is approximately 1 GeV at nominal gradients. Major installations at CERN, DESY, KEK and CEBAF have provided large increments to the installed base and valuable operational experience. A selection of test data and operational experience gathered to date is reviewed

  2. First demonstration and performance of an injection locked continuous wave magnetron to phase control a superconducting cavity

    Directory of Open Access Journals (Sweden)

    A. C. Dexter

    2011-03-01

    Full Text Available The applications of magnetrons to high power proton and cw electron linacs are discussed. An experiment is described where a 2.45 GHz magnetron has been used to drive a single cell superconducting cavity. With the magnetron injection locked, a modest phase control accuracy of 0.95° rms has been demonstrated. Factors limiting performance have been identified.

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

    International Nuclear Information System (INIS)

    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)

  4. Development of L-band niobium superconducting RF cavities with high accelerating field

    International Nuclear Information System (INIS)

    Saito, Kenji; Noguchi, Shuichi; Ono, Masaaki; Kako, Eiji; Shishido, Toshio; Matsuoka, Masanori; Suzuki, Takafusa; Higuchi, Tamawo.

    1994-01-01

    Superconducting RF cavity is a candidate for the TeV energy e + /e - linear collider of next generation if the accelerating field is improved to 25-30 MV/m and much cost down is achieved in cavity fabrication. Since 1990, KEK has continued R and D of L-band niobium superconducting cavities focusing on the high field issue. A serious problem like Q-degradation due to vacuum discharge came out on the way, however, it has been overcome and presently all of cavities which were annealed at 1400degC achieved the accelerating field of >25 MV/m with enough Qo value. Recent results on single cell cavities are described in this paper. (author)

  5. Vacuum-induced Stark shifts for quantum logic using a collective system in a high-quality dispersive cavity

    International Nuclear Information System (INIS)

    Gabris, A.; Agarwal, G.S.

    2005-01-01

    A collective system of atoms in a high-quality cavity can be described by a nonlinear interaction which arises due to the Lamb shift of the energy levels due to the cavity vacuum [Agarwal et al., Phys. Rev. A 56, 2249 (1997)]. We show how this collective interaction can be used to perform quantum logic. In particular we produce schemes to realize controlled-NOT gates not only for two-qubit but also for three-qubit systems. We also discuss realizations of Toffoli gates. Our effective Hamiltonian is also realized in other systems such as trapped ions or magnetic molecules

  6. Numerical investigations on the performance of external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper

    2004-01-01

    The performance of an external-cavity mode-locked semiconductor laser is analyzed theoretically and numerically. Passive mode-locking is described using a fully-distributed time-domain model including fast effects, spectral hole burning and carrier heating. We provide optimization rules in order ...

  7. Cavity-enhanced surface-plasmon resonance sensing: modeling and performance

    International Nuclear Information System (INIS)

    Giorgini, A; Avino, S; Malara, P; Zullo, R; Gagliardi, G; Homola, J; De Natale, P

    2014-01-01

    We investigate the performance of a surface-plasmon-resonance refractive-index (RI) sensor based on an optical resonator. The resonator transforms RI changes of liquid samples, interacting with the surface plasmon excited by near-infrared light, into a variation of the intra-cavity optical loss. Cavity ring-down measurements are provided as a proof of concept of RI sensing on calibrated mixtures. A characterization of the overall sensor response and noise features as well as a discussion on possible improvements is carried out. A reproducibility analysis shows that a resolution of 10 −7 –10 −8  RIU is within reach over observation times of 1–30 s. The ultimate resolution is set only by intrinsic noise features of the cavity-based method, pointing to a potential limit below 10 −10  RIU/√Hz. (paper)

  8. Summary of performance of superconducting radio-frequency cavities built from CBMM niobium ingots

    International Nuclear Information System (INIS)

    Ciovati, Gianluigi; Dhakal, Pashupati; Kneisel, Peter; Myneni, Ganapati R.

    2015-01-01

    Several Nb ingots have been provided by CBMM to Jefferson Lab since 2004 as part of an R&D collaboration aimed at evaluating the performance of superconducting radio-frequency cavities built from ingots with different purity, as a results of different ingot production processes. Approximately 32 multi- and single-cell cavities with resonant frequency between ∼1.3-2.3 GHz were built, treated and tested at 2 K at Jefferson Lab between 2004 and 2014. The average peak surface field achieved in cavities made of RRR∼260 and RRR∼100-150 ingots was (119 ± 4) mT and (100 ± 8) mT, respectively. Higher quality factor values at 2.0 K have been measured in medium-purity, compared to higher purity material

  9. Summary of performance of superconducting radio-frequency cavities built from CBMM niobium ingots

    Science.gov (United States)

    Ciovati, Gianluigi; Dhakal, Pashupati; Kneisel, Peter; Myneni, Ganapati R.

    2015-12-01

    Several Nb ingots have been provided by CBMM to Jefferson Lab since 2004 as part of an R&D collaboration aimed at evaluating the performance of superconducting radio-frequency cavities built from ingots with different purity, as a results of different ingot production processes. Approximately 32 multi- and single-cell cavities with resonant frequency between ˜1.3-2.3 GHz were built, treated and tested at 2 K at Jefferson Lab between 2004 and 2014. The average peak surface field achieved in cavities made of RRR˜260 and RRR˜100-150 ingots was (119 ± 4) mT and (100 ± 8) mT, respectively. Higher quality factor values at 2.0 K have been measured in medium-purity, compared to higher purity material.

  10. High Performance Walls in Hot-Dry Climates

    Energy Technology Data Exchange (ETDEWEB)

    Hoeschele, Marc [National Renewable Energy Lab. (NREL), Golden, CO (United States); Springer, David [National Renewable Energy Lab. (NREL), Golden, CO (United States); Dakin, Bill [National Renewable Energy Lab. (NREL), Golden, CO (United States); German, Alea [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-01-01

    High performance walls represent a high priority measure for moving the next generation of new homes to the Zero Net Energy performance level. The primary goal in improving wall thermal performance revolves around increasing the wall framing from 2x4 to 2x6, adding more cavity and exterior rigid insulation, achieving insulation installation criteria meeting ENERGY STAR's thermal bypass checklist, and reducing the amount of wood penetrating the wall cavity.

  11. Effect of low temperature baking in nitrogen on the performance of a niobium superconducting radio frequency cavity

    Directory of Open Access Journals (Sweden)

    Pashupati Dhakal

    2018-03-01

    Full Text Available We report the rf performance of a single cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of 120–160 °C with a nitrogen partial pressure of ∼25  m Torr. This increase in quality factor as well as the Q-rise phenomenon (anti-Q-slope is similar to those previously obtained with high temperature nitrogen doping as well as titanium doping. In this study, a cavity N_{2}-treated at 120 °C and at 140 °C showed no degradation in accelerating gradient, however the accelerating gradient was reduced by ∼25% with a 160 °C N_{2} treatment, compared to the baseline tests after electropolishing. Sample coupons treated in the same conditions as the cavity were analyzed by scanning electron microscope, x-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a complex surface composition of Nb_{2}O_{5}, NbO and NbN_{(1−x}O_{x} within the rf penetration depth. Furthermore, magnetization measurements showed no significant change on bulk superconducting properties.

  12. Effect of low temperature baking in nitrogen on the performance of a niobium superconducting radio frequency cavity

    Science.gov (United States)

    Dhakal, Pashupati; Chetri, Santosh; Balachandran, Shreyas; Lee, Peter J.; Ciovati, Gianluigi

    2018-03-01

    We report the rf performance of a single cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of 120 - 160 °C with a nitrogen partial pressure of ˜25 m Torr . This increase in quality factor as well as the Q -rise phenomenon (anti-Q -slope) is similar to those previously obtained with high temperature nitrogen doping as well as titanium doping. In this study, a cavity N2 -treated at 120 °C and at 140 °C showed no degradation in accelerating gradient, however the accelerating gradient was reduced by ˜25 % with a 160 °C N2 treatment, compared to the baseline tests after electropolishing. Sample coupons treated in the same conditions as the cavity were analyzed by scanning electron microscope, x-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a complex surface composition of Nb2O5 , NbO and NbN(1 -x )Ox within the rf penetration depth. Furthermore, magnetization measurements showed no significant change on bulk superconducting properties.

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

    International Nuclear Information System (INIS)

    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

  14. Sparking limits, cavity loading, and beam breakup instability associated with high-current rf linacs

    International Nuclear Information System (INIS)

    Faehl, R.J.; Lemons, D.S.; Thode, L.E.

    1982-01-01

    The limitations on high-current rf linacs due to gap sparking, cavity loading, and the beam breakup instability are studied. It appears possible to achieve cavity accelerating gradients as high as 35 MV/m without sparking. Furthermore, a linear analysis, as well as self-consistent particle simulations of a multipulsed 10 kA beam, indicated that only a negligible small fraction of energy is radiated into nonfundamental cavity modes. Finally, the beam breakup instability is analyzed and found to be able to magnify initial radial perturbations by a factor of no more than about 20 during the beam transit time through a 1 GeV accelerator

  15. High-power RF cavity R ampersand D for the PEP-II B Factory

    International Nuclear Information System (INIS)

    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

  16. In vitro marginal adaptation of high-viscosity resin composite restorations bonded to dentin cavities.

    Science.gov (United States)

    Rahiotis, Christos; Tzoutzas, John; Kakaboura, Afrodite

    2004-01-01

    The aim of this study was to evaluate the marginal adaptation of high-viscosity resin composite restoratives bonded to dentin in a cylindrical cavity model. The buccal enamel of 64 human premolars was removed and cylindrical cavities 3 mm in diameter and 1.3 mm in depth were prepared on each dentin surface. The cavities were divided into 8 groups of 8 cavities each and restored according to the manufacturers' instructions with the following adhesive/composite systems: Bond 1/Alert, Stae/Glacier, OptiBond Solo/Prodigy Condensable, One-Step/Pyramid, Solidbond/Solitaire, Prime&Bond NT/Surefil, One Coat Bond/Synergy, and Scotchbond 1/Z250. The composite surfaces were pressed against mylar strips, covered with cover slips, and photopolymerized in a single increment for 40 s. The restorations were polished with wet SiC papers of 320 to 1000 grit size to expose dentin margins. The marginal adaptation was evaluated immediately after photopolymerization and again after 1 week of storage in water at 37 +/- 1 degrees C. Evaluation was performed under a metallographic microscope at 200X magnification by recording the frequency of gap-free restorations (GF), the percentage length of the debonded margins relative to the cavity periphery (DM), the width of the maximum marginal gap (MG), and the marginal index (MI = MG x DM / 100). The results were statistically analyzed with one-way ANOVA and the Mann-Whitney U-test at alpha = 0.05. No incidence of gaps was found in 62.5% of One Coat Bond/Synergy and 37.5% of OptiBond Solo/Prodigy Condensable restorations. All the other restorative systems exhibited restorations with gaps. One Coat Bond/Synergy, Scotchbond 1/Z250, and OptiBond Solo/Prodigy Condensable were the groups with the lowest DM values, while Stae/Glacier showed the highest DM values. One Coat Bond/Synergy and OptiBond Solo/Prodigy Condensable revealed the lowest MI values and Stae/Glacier the highest. No statistically significant differences were recorded between

  17. The Path to High Q-Factors in Superconducting Accelerating Cavities: Flux Expulsion and Surface Resistance Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Martinello, Martina [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-12-01

    causing temperature rising. The physics behind the magnetic flux expulsion is also analyzed, showing that during a fast cooldown the magnetic field structures, called vortices, tend to move in the same direction of the thermal gradient, from the Meissner state region to the mixed state region, minimizing the Gibbs free energy. On the other hand, during a slow cool down, not only the vortices movement is limited by the absence of thermal gradients, but, also, at the end of the superconducting transition, the magnetic field concentrates along randomly distributed normal-conducting region from which it cannot be expelled anymore. The systematic study of the surface resistance components performed for the different surface treatments, reveals that the BCS surface resistance and the trapped flux surface resistance have opposite trends as a function of the surface impurity content, defined by the mean free path. At medium field value, the BCS surface resistance is minimized for nitrogen-doped cavities and significantly larger for standard niobium cavities. On the other hand, Nitrogen-doped cavities show larger dissipation due to trapped flux. This is consequence of the bell-shaped trend of the trapped flux sensitivity as a function of the mean free path. Such experimental findings allow also a better understanding of the RF dissipation due to trapped flux. The best compromise between all the surface resistance components, taking into account the possibility of trapping some external magnetic field, is given by light nitrogen-doping treatments. However, the beneficial effects of the nitrogen-doping is completely lost when large amount of magnetic field is trapped during the cooldown, underlying the importance of both cooldown and magnetic field shielding optimization in high quality factors cryomodules.

  18. The path to high Q-factors in superconducting accelerating cavities: Flux expulsion and surface resistance optimization

    Science.gov (United States)

    Martinello, Martina

    causing temperature rising. The physics behind the magnetic flux expulsion is also analyzed, showing that during a fast cooldown the magnetic field structures, called vortices, tend to move in the same direction of the thermal gradient, from the Meissner state region to the mixed state region, minimizing the Gibbs free energy. On the other hand, during a slow cool down, not only the vortices movement is limited by the absence of thermal gradients, but, also, at the end of the superconducting transition, the magnetic field concentrates along randomly distributed normal-conducting region from which it cannot be expelled anymore. The systematic study of the surface resistance components performed for the different surface treatments, reveals that the BCS surface resistance and the trapped flux surface resistance have opposite trends as a function of the surface impurity content, defined by the mean free path. At medium field value, the BCS surface resistance is minimized for nitrogen-doped cavities and significantly larger for standard niobium cavities. On the other hand, Nitrogen-doped cavities show larger dissipation due to trapped flux. This is consequence of the bell-shaped trend of the trapped flux sensitivity as a function of the mean free path. Such experimental findings allow also a better understanding of the RF dissipation due to trapped flux. The best compromise between all the surface resistance components, taking into account the possibility of trapping some external magnetic field, is given by light nitrogen-doping treatments. However, the beneficial effects of the nitrogen-doping is completely lost when large amount of magnetic field is trapped during the cooldown, underlying the importance of both cooldown and magnetic field shielding optimization in high quality factors cryomodules.

  19. Effect of High Solenoidal Magnetic Fields on Breakdown Voltages of High Vacuum 805 MHz Cavities

    CERN Document Server

    Moretti, A; Geer, S; Qian, Z

    2004-01-01

    The demonstration of muon ionization cooling by a large factor is necessary to demonstrate the feasilibility of a collider or neutrino factory. An important cooling experiment, MICE [1], has been proposed to demonstrate 10 % cooling which will validate the technology. Ionization cooling is accomplished by passing a high-emittance beam in a multi-Tesla solenoidal channel alternately through regions of low Z material and very high accelerating RF Cavities. To determine the effect of very large solenoidal magnetic fields on the generations of Dark current, X-Rays and breakdown Voltage gradients of vacuum RF cavities, a test facility has been established at Fermilab in Lab G. This facility consists of a 12 MW 805 MHz RF station, and a large bore 5 T solenoidal superconducting magnet containing a pill box type Cavity with thin removable window apertures allowing dark current studies and breakdown studies of different materials. The results of this study will be presented. The study has shown that the peak achievab...

  20. Free convection performance of circular cavities having two active curved vertical sides and two inactive curved horizontal sides

    International Nuclear Information System (INIS)

    Ridouane, El Hassan; Campo, Antonio

    2006-01-01

    A detailed review of the archival reveals that the heat transfer and fluid flow characteristics of circular cavities have not been investigated so far and of course their physical features are not understood. A prominent application of these cavities arises in the miniaturized packaging of electronic components that are subject to strict constraints. This paper addresses primarily steady-state laminar natural convection of air in a circular cavity of diameter H inscribed in a square cavity of side H where the corresponding sides are in contact at four points. A third cavity, an arc-square cavity whose shape lies between the square and circular cavity shapes is included in the analysis. The finite volume method is used to perform the numerical simulations. The methodology takes into account the second-order-accurate QUICK scheme for the discretization of the convective term, whereas the pressure-velocity coupling is handled with the SIMPLE scheme. Since the air is not assumed a Boussinesq gas, it was decided to take all thermophysical properties as temperature-dependent. In the end, it has been demonstrated that the circular cavity possesses a superior balance between heat transfer enhancement and size in cross-section area in comparison with the standard square cavity. The side of the square cavity is similar to the diameter of the circular cavity

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

    International Nuclear Information System (INIS)

    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

  2. Numerical Investigation of Vertical Cavity Lasers With High-Contrast Gratings Using the Fourier Modal Method

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza; Mørk, Jesper; Chung, Il-Sug

    2016-01-01

    We explore the use of a modal expansion technique, Fourier modal method (FMM), for investigating the optical properties of vertical cavities employing high-contrast gratings (HCGs). Three techniques for determining the resonance frequency and quality factor (Q-factor) of a cavity mode are compared......, the scattering losses of several HCG-based vertical cavities with inplane heterostructures which have promising prospects for fundamental physics studies and on-chip laser applications, are investigated. This type of parametric study of 3D structures would be numerically very demanding using spatial...

  3. High power tests of the prototype 352 MHz beta 0.85 five cell cavity for the TRASCO project

    International Nuclear Information System (INIS)

    Chiaveri, E.; Losito, R.; Calatroni, S.

    2003-01-01

    The Five-cell beta 0.85 cavities built at CERN for the development of the TRASCO project is fully tested at the CERN SL-CT Test Bench. The cavity, built using the standard Niobium on Copper technique, was previously tested in a vertical cryostat, showing Qo and Field exceeding the design goal for the TRASCO Project (2.5x10 9 and 5.5 MV/m at 4.5 K). After the successful test we decided to check the performances of the cavity installed in a horizontal Cryostat and equipped with a LEP-II Type high power main coupler and HOM couplers. The cavity was equipped with the Helium Tank, Tuners and couplers at CERN and tested at the SL-CT facility at CERN under a collaboration agreement between INFN and CERN. The behavior of the fully equipped cavity substantially confirmed the results of the preliminary production tests in the vertical Cryostat. The quality factor at low field was substantially unchanged. No MP activity was detected confirming the soundness of the design and the quality of the surface treatment. (author)

  4. High-Q Fabry–Pérot Micro-Cavities for High-Sensitivity Volume Refractometry

    Directory of Open Access Journals (Sweden)

    Noha Gaber

    2018-01-01

    Full Text Available This work reports a novel structure for a Fabry–Pérot micro cavity that combines the highest reported quality factor for an on-chip Fabry–Pérot resonator that exceeds 9800, and a very high sensitivity for an on-chip volume refractometer based on a Fabry–Pérot cavity that is about 1000 nm/refractive index unit (RIU. The structure consists of two cylindrical Bragg micromirrors that achieve confinement of the Gaussian beam in the plan parallel to the chip substrate, while for the perpendicular plan, external fiber rod lenses (FRLs are placed in the optical path of the input and the output of the cavity. This novel structure overcomes number of the drawbacks presented in previous designs. The analyte is passed between the mirrors, enabling its detection from the resonance peak wavelengths of the transmission spectra. Mixtures of ethanol and deionized (DI-water with different ratios are used as analytes with different refractive indices to exploit the device as a micro-opto-fluidic refractometer. The design criteria are detailed and the modeling is based on Gaussian-optics equations, which depicts a scenario closer to reality than the usually used ray-optics modeling.

  5. Experimental investigation on combustion performance of cavity-strut injection of supercritical kerosene in supersonic model combustor

    Science.gov (United States)

    Sun, Ming-bo; Zhong, Zhan; Liang, Jian-han; Wang, Hong-bo

    2016-10-01

    Supersonic combustion with cavity-strut injection of supercritical kerosene in a model scramjet engine was experimentally investigated in Mach 2.92 facility with the stagnation temperatures of approximately 1430 K. Static pressure distribution in the axial direction was determined using pressure transducers installed along the centerline of the model combustor top walls. High speed imaging camera was used to capture flame luminosity and combustion region distribution. Multi-cavities were used to and stabilize the combustion in the supersonic combustor. Intrusive injection by thin struts was used to enhance the fuel-air mixing. Supercritical kerosene at temperatures of approximately 780 K and various pressures was prepared using a heat exchanger driven by the hot gas from a pre-burner and injected at equivalence ratios of approximately 1.0. In the experiments, combustor performances with different strut injection schemes were investigated and compared to direct wall injection scheme based on the measured static pressure distributions, the specific thrust increments and the images obtained by high-speed imaging camera. The experimental results showed that the injection by thin struts could obtain an enhanced mixing in the field but could not acquire a steady flame when mixing field cannot well match cavity separation region. There is no significant difference on performance between different schemes since the unsteady intermittent and oscillating flame leads to no actual combustion efficiency improvement.

  6. Study of Electron Swarm in High Pressure Hydrogen Gas Filled RF Cavities

    International Nuclear Information System (INIS)

    Yonehara, K.; Chung, M.; Jansson, A.; Moretti, A.; Popovic, M.; Tollestrup, A.; Alsharo'a, M.; Johnson, R.P.; Notani, M.; Oka, T.; Wang, H.

    2010-01-01

    A high pressure hydrogen gas filled RF cavity has been proposed for use in the muon collection system for a muon collider. It allows for high electric field gradients in RF cavities located in strong magnetic fields, a condition frequently encountered in a muon cooling channel. In addition, an intense muon beam will generate an electron swarm via the ionization process in the cavity. A large amount of RF power will be consumed into the swarm. We show the results from our studies of the HV RF breakdown in a cavity without a beam and present some results on the resulting electron swarm dynamics. This is preliminary to actual beam tests which will take place late in 2010.

  7. Comparison of Deformation in High-Purity Single/Large Grain and Polycrystalline Niobium Superconducting Cavities

    International Nuclear Information System (INIS)

    Ganapati Rao Myneni; Peter Kneisel

    2005-01-01

    The current approach for the fabrication of superconducting radio frequency (SRF) cavities is to roll and deep draw sheets of polycrystalline high-purity niobium. Recently, a new technique was developed at Jefferson Laboratory that enables the fabrication of single-crystal high-purity Nb SRF cavities. To better understand the differences between SRF cavities fabricated out of fine-grained polycrystalline sheet in the standard manner and single crystal cavities fabricated by the new technique, two half-cells were produced according to the two different procedures and compared using a variety of analytical techniques including optical microscopy, scanning laser confocal microscopy, profilometry, and X-ray diffraction. Crystallographic orientations, texture, and residual stresses were determined in the samples before and after forming and this poster presents the results of this ongoing study

  8. Development of a high-resolution cavity-beam position monitor

    Science.gov (United States)

    Inoue, Yoichi; Hayano, Hitoshi; Honda, Yosuke; Takatomi, Toshikazu; Tauchi, Toshiaki; Urakawa, Junji; Komamiya, Sachio; Nakamura, Tomoya; Sanuki, Tomoyuki; Kim, Eun-San; Shin, Seung-Hwan; Vogel, Vladimir

    2008-06-01

    We have developed a high-resolution cavity-beam position monitor (BPM) to be used at the focal point of the ATF2, which is a test beam line that is now being built to demonstrate stable orbit control at ˜nanometer resolution. The design of the cavity structure was optimized for the Accelerator Test Facility (ATF) beam in various ways. For example, the cavity has a rectangular shape in order to isolate two dipole modes in orthogonal directions, and a relatively thin gap that is less sensitive to trajectory inclination. A two stage homodyne mixer with highly sensitive electronics and phase-sensitive detection was also developed. Two BPM blocks, each containing two cavity BPMs, were installed in the existing ATF beam line using a rigid support frame. After testing the basic characteristics, we measured the resolution using three BPMs. The system demonstrated 8.7 nm position resolution over a dynamic range of 5μm.

  9. Fundamental cavity impedance and longitudinal coupled-bunch instabilities at the High Luminosity Large Hadron Collider

    Directory of Open Access Journals (Sweden)

    P. Baudrenghien

    2017-01-01

    Full Text Available The interaction between beam dynamics and the radio frequency (rf station in circular colliders is complex and can lead to longitudinal coupled-bunch instabilities at high beam currents. The excitation of the cavity higher order modes is traditionally damped using passive devices. But the wakefield developed at the cavity fundamental frequency falls in the frequency range of the rf power system and can, in theory, be compensated by modulating the generator drive. Such a regulation is the responsibility of the low-level rf (llrf system that measures the cavity field (or beam current and generates the rf power drive. The Large Hadron Collider (LHC rf was designed for the nominal LHC parameter of 0.55 A DC beam current. At 7 TeV the synchrotron radiation damping time is 13 hours. Damping of the instability growth rates due to the cavity fundamental (400.789 MHz can only come from the synchrotron tune spread (Landau damping and will be very small (time constant in the order of 0.1 s. In this work, the ability of the present llrf compensation to prevent coupled-bunch instabilities with the planned high luminosity LHC (HiLumi LHC doubling of the beam current to 1.1 A DC is investigated. The paper conclusions are based on the measured performances of the present llrf system. Models of the rf and llrf systems were developed at the LHC start-up. Following comparisons with measurements, the system was parametrized using these models. The parametric model then provides a more realistic estimation of the instability growth rates than an ideal model of the rf blocks. With this modeling approach, the key rf settings can be varied around their set value allowing for a sensitivity analysis (growth rate sensitivity to rf and llrf parameters. Finally, preliminary measurements from the LHC at 0.44 A DC are presented to support the conclusions of this work.

  10. Radio frequency regenerative oscillations in monolithic high-Q/V heterostructured photonic crystal cavities

    International Nuclear Information System (INIS)

    Yang, Jinghui; Gu, Tingyi; Zheng, Jiangjun; Wei Wong, Chee; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee

    2014-01-01

    We report temporal and spectral domain observation of regenerative oscillation in monolithic silicon heterostructured photonic crystals cavities with high quality factor to mode volume ratios (Q/V). The results are interpreted by nonlinear coupled mode theory (CMT) tracking the dynamics of photon, free carrier population, and temperature variations. We experimentally demonstrate effective tuning of the radio frequency tones by laser-cavity detuning and laser power levels, confirmed by the CMT simulations with sensitive input parameters

  11. High Quality Plasmonic Sensors Based on Fano Resonances Created through Cascading Double Asymmetric Cavities

    OpenAIRE

    Zhang, Xiangao; Shao, Mingzhen; Zeng, Xiaoqi

    2016-01-01

    In this paper, a type of compact nanosensor based on a metal-insulator-metal structure is proposed and investigated through cascading double asymmetric cavities, in which their metal cores shift along different axis directions. The cascaded asymmetric structure exhibits high transmission and sharp Fano resonance peaks via strengthening the mutual coupling of the cavities. The research results show that with the increase of the symmetry breaking in the structure, the number of Fano resonances ...

  12. Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing

    OpenAIRE

    Yaseen, Mohammad; Yang, Yi-Chun; Shih, Min-Hsiung; Chang, Yia-Chung

    2015-01-01

    We numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (FEM) simulations. We showed that when two PhC NB cavities separated by a small gap are evanescently coupled, the variation in the gap width significantly changes the coupling efficiency between the ...

  13. A study on the high-order mode oscillation in a four-cavity intense relativistic klystron amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying-Hui; Niu, Xin-Jian; Wang, Hui [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu (China); Jia, Nan; Duan, Yaoyong [The Chinese People' s Armed Police Force Academy, Hebei (China); Li, Zheng-Hong [Science and Technology on High Power Microwave Laboratory, Institute of Applied Electronics, CAEP, Mianyang (China); Cheng, Hui [Microwave Department, Sichuan Jiuzhou Electric Appliance Group Co., Ltd., Mianyang (China); Yang, Xiao-Chuan [Computational Aerodynamics Institute, China Aerodynamics Research and Development Center, Mianyang (China)

    2016-07-15

    The high-order mode oscillation is studied in designing a four-cavity intense relativistic klystron amplifier. The reason for the oscillation caused by high-order modes and a method to suppress these kinds of spurious modes are found through theoretical analyses and the study on the influence of major parameters of a high frequency structure (such as the oscillation frequency of cavities, the cavity Q value, the length of drift tube section, and the characteristic impedance). Based on much simulation, a four-cavity intense relativistic klystron amplifier with a superior performance has been designed, built, and tested. An output power of 2.22 GW corresponding to 27.4% efficiency and 61 dB gain has been obtained. Moreover, the high-order mode oscillation is suppressed effectively, and an output power of 1.95 GW corresponding to 26% efficiency and 62 dB gain has been obtained in our laboratory.

  14. Monitoring Thermal Performance of Hollow Bricks with Different Cavity Fillers in Difference Climate Conditions

    Science.gov (United States)

    Pavlík, Zbyšek; Jerman, Miloš; Fořt, Jan; Černý, Robert

    2015-03-01

    Hollow brick blocks have found widespread use in the building industry during the last decades. The increasing requirements to the thermal insulation properties of building envelopes given by the national standards in Europe led the brick producers to reduce the production of common solid bricks. Brick blocks with more or less complex systems of internal cavities replaced the traditional bricks and became dominant on the building ceramics market. However, contrary to the solid bricks where the thermal conductivity can easily be measured by standard methods, the complex geometry of hollow brick blocks makes the application of common techniques impossible. In this paper, a steady-state technique utilizing a system of two climatic chambers separated by a connecting tunnel for sample positioning is used for the determination of the thermal conductivity, thermal resistance, and thermal transmittance ( U value) of hollow bricks with the cavities filled by air, two different types of mineral wool, polystyrene balls, and foam polyurethane. The particular brick block is provided with the necessary temperature- and heat-flux sensors and thermally insulated in the tunnel. In the climatic chambers, different temperatures are set. After steady-state conditions are established in the measuring system, the effective thermal properties of the brick block are calculated using the measured data. Experimental results show that the best results are achieved with hydrophilic mineral wool as a cavity filler; the worst performance exhibits the brick block with air-filled cavities.

  15. The combination of high Q factor and chirality in twin cavities and microcavity chain

    Science.gov (United States)

    Song, Qinghai; Zhang, Nan; Zhai, Huilin; Liu, Shuai; Gu, Zhiyuan; Wang, Kaiyang; Sun, Shang; Chen, Zhiwei; Li, Meng; Xiao, Shumin

    2014-01-01

    Chirality in microcavities has recently shown its bright future in optical sensing and microsized coherent light sources. The key parameters for such applications are the high quality (Q) factor and large chirality. However, the previous reported chiral resonances are either low Q modes or require very special cavity designs. Here we demonstrate a novel, robust, and general mechanism to obtain the chirality in circular cavity. By placing a circular cavity and a spiral cavity in proximity, we show that ultra-high Q factor, large chirality, and unidirectional output can be obtained simultaneously. The highest Q factors of the non-orthogonal mode pairs are almost the same as the ones in circular cavity. And the co-propagating directions of the non-orthogonal mode pairs can be reversed by tuning the mode coupling. This new mechanism for the combination of high Q factor and large chirality is found to be very robust to cavity size, refractive index, and the shape deformation, showing very nice fabrication tolerance. And it can be further extended to microcavity chain and microcavity plane. We believe that our research will shed light on the practical applications of chirality and microcavities. PMID:25262881

  16. Highly Sensitive Reentrant Cavity-Microstrip Patch Antenna Integrated Wireless Passive Pressure Sensor for High Temperature Applications

    Directory of Open Access Journals (Sweden)

    Fei Lu

    2017-01-01

    Full Text Available A novel reentrant cavity-microstrip patch antenna integrated wireless passive pressure sensor was proposed in this paper for high temperature applications. The reentrant cavity was analyzed from aspects of distributed model and equivalent lumped circuit model, on the basis of which an optimal sensor structure integrated with a rectangular microstrip patch antenna was proposed to better transmit/receive wireless signals. In this paper, the proposed sensor was fabricated with high temperature resistant alumina ceramic and silver metalization with weld sealing, and it was measured in a hermetic metal tank with nitrogen pressure loading. It was verified that the sensor was highly sensitive, keeping stable performance up to 300 kPa with an average sensitivity of 981.8 kHz/kPa at temperature 25°C, while, for high temperature measurement, the sensor can operate properly under pressure of 60–120 kPa in the temperature range of 25–300°C with maximum pressure sensitivity of 179.2 kHz/kPa. In practical application, the proposed sensor is used in a method called table lookup with a maximum error of 5.78%.

  17. Cryostat for TRISTAN superconducting cavity

    International Nuclear Information System (INIS)

    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. High efficiency and high-energy intra-cavity beam shaping laser

    International Nuclear Information System (INIS)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-01-01

    We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%. (paper)

  19. High efficiency and high-energy intra-cavity beam shaping laser

    Science.gov (United States)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-09-01

    We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%.

  20. Effect of cooldown and residual magnetic field on the performance of niobium–copper clad superconducting radio-frequency cavity

    International Nuclear Information System (INIS)

    Dhakal, Pashupati; Ciovati, Gianluigi

    2017-01-01

    Here, we present the results of rf measurements on a niobium–copper clad superconducting radio-frequency cavity with different cooldown conditions and residual magnetic field in a vertical test Dewar in order to explore the effect of thermal current induced magnetic field and its trapping on the performance of the cavity. The residual resistance, extracted from the Q 0 (T) curves in the temperature range 4.3–1.5 K, showed no dependence on a temperature gradient along the cavity during the cooldown across the critical temperature up to ~50 K m –1 . The rf losses due to the trapping of residual magnetic field during the cavity cooldown were found to be ~4.3 nΩ μT –1 , comparable to the values measured in bulk niobium cavities. An increase of residual resistance following multiple cavity quenches was observed along with evidence of trapping of magnetic flux generated by thermoelectric currents.

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

    CERN Document Server

    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-...

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

    Science.gov (United States)

    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.

  3. High performance homes

    DEFF Research Database (Denmark)

    Beim, Anne; Vibæk, Kasper Sánchez

    2014-01-01

    Can prefabrication contribute to the development of high performance homes? To answer this question, this chapter defines high performance in more broadly inclusive terms, acknowledging the technical, architectural, social and economic conditions under which energy consumption and production occur....... Consideration of all these factors is a precondition for a truly integrated practice and as this chapter demonstrates, innovative project delivery methods founded on the manufacturing of prefabricated buildings contribute to the production of high performance homes that are cost effective to construct, energy...

  4. Simulation of the High-Pass Filter for 56MHz Cavity for RHIC

    International Nuclear Information System (INIS)

    Wu, Q.; Ben-Zvi, I.

    2010-01-01

    The 56MHz Superconducting RF (SRF) cavity for RHIC places high demands High Order Mode (HOM) damping, as well as requiring a high field at gap with fundamental mode frequency. The damper of 56MHz cavity is designed to extract all modes to the resistance load outside, including the fundamental mode. Therefore, the circuit must incorporate a high-pass filter to reflect back the fundamental mode into the cavity. In this paper, we show the good frequency response map obtained from our filter's design. We extract a circuit diagram from the microwave elements that simulate well the frequency spectrum of the finalized filter. We also demonstrate that the power dissipation on the filter over its frequency range is small enough for cryogenic cooling.

  5. Development of a movable plunger tuner for the high-power RF cavity for the PEP-II B-factory

    International Nuclear Information System (INIS)

    Schwarz, H.D.; Fant, K.; Judkins, J.G.

    1997-05-01

    A 10 cm diameter by 5 cm travel plunger tuner was developed for the PEP-II RF copper cavity system. The single cell cavity including the tuner is designed to operate up to 150 kW of dissipated RF power are specially placed 8.5 cm away from the inside wall of the cavity to avoid fundamental and higher order mode resonances. The spring fingers are made of dispersion-strengthened copper to accommodate relatively high heating. The design, alignment, testing and performance of the tuner is described

  6. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    Science.gov (United States)

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  7. Measurement of the high-field Q-drop in a high-purity large-grain niobium cavity for different oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi; Kneisel, Peter; gurevich, alex

    2007-06-01

    The most challenging issue for understanding the performance of superconducting radio-frequency (rf) cavities made of high-purity (residual resistivity ratio > 200) niobium is due to a sharp degradation (“Q-drop”) of the cavity quality factor Q0(Bp) as the peak surface magnetic field (Bp) exceeds about 90 mT, in the absence of field emission. In addition, a low-temperature (100 – 140 C) “in-situ” baking of the cavity was found to be beneficial in reducing the Q-drop. In this contribution, we present the results from a series of rf tests at 1.7 K and 2.0 K on a single-cell cavity made of high-purity large (with area of the order of few cm2) grain niobium which underwent various oxidation processes, after initial buffered chemical polishing, such as anodization, baking in pure oxygen atmosphere and baking in air up to 180 °C, with the objective of clearly identifying the role of oxygen and the oxide layer on the Q-drop. During each rf test a temperature mapping system allows measuring the local temperature rise of the cavity outer surface due to rf losses, which gives information about the losses location, their field dependence and space distribution. The results confirmed that the depth affected by baking is about 20 – 30 nm from the surface and showed that the Q-drop did not re-appear in a previously baked cavity by further baking at 120 °C in pure oxygen atmosphere or in air up to 180 °C. These treatments increased the oxide thickness and oxygen concentration, measured on niobium samples which were processed with the cavity and were analyzed with Transmission Electron Microscope (TEM) and Secondary Ion Mass Spectroscopy (SIMS). Nevertheless, the performance of the cavity after air baking at 180 °C degraded significantly and the temperature maps showed high losses, uniformly distributed on the surface, which could be completely recovered only by a post-purification treatment at 1250 °C. A statistic of the position of the “hot-spots” on the

  8. Measurement of the high-field Q drop in a high-purity large-grain niobium cavity for different oxidation processes

    Directory of Open Access Journals (Sweden)

    G. Ciovati

    2007-06-01

    Full Text Available The most challenging issue for understanding the performance of superconducting radio-frequency (rf cavities made of high-purity (residual resistivity ratio >200 niobium is due to a sharp degradation (“Q-drop” of the cavity quality factor Q_{0}(B_{p} as the peak surface magnetic field (B_{p} exceeds about 90 mT, in the absence of field emission. In addition, a low-temperature (100–140°C in situ baking of the cavity was found to be beneficial in reducing the Q-drop. In this contribution, we present the results from a series of rf tests at 1.7 and 2.0 K on a single-cell cavity made of high-purity large (with area of the order of few cm^{2} grain niobium which underwent various oxidation processes, after initial buffered chemical polishing, such as anodization, baking in pure oxygen atmosphere, and baking in air up to 180°C, with the objective of clearly identifying the role of oxygen and the oxide layer on the Q-drop. During each rf test a temperature mapping system allows measuring the local temperature rise of the cavity outer surface due to rf losses, which gives information about the losses location, their field dependence, and space distribution. The results confirmed that the depth affected by baking is about 20–30 nm from the surface and showed that the Q-drop did not reappear in a previously baked cavity by further baking at 120°C in pure oxygen atmosphere or in air up to 180°C. These treatments increased the oxide thickness and oxygen concentration, measured on niobium samples which were processed with the cavity and were analyzed with transmission electron microscope and secondary ion mass spectroscopy. Nevertheless, the performance of the cavity after air baking at 180°C degraded significantly and the temperature maps showed high losses, uniformly distributed on the surface, which could be completely recovered only by a postpurification treatment at 1250°C. A statistic of the position of the “hot spots” on the

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Performance of a 1200 m long suspended Fabry-Perot cavity

    CERN Document Server

    Freise, A; Gossler, S; Grote, H; Heinzel, G; Lück, H B; Robertson, D I; Strain, K A; Ward, H; Willke, B; Hough, J; Danzmann, K

    2002-01-01

    Using one arm of the Michelson interferometer and the power recycling mirror of the interferometric gravitational wave detector GEO 600, we created a Fabry-Perot cavity with a length of 1200 m. The main purpose of this experiment was to gather first experience with the main optics, its suspensions and the corresponding control systems. The residual displacement of a main mirror is about 150 nm rms. By stabilizing the length of the 1200 m long cavity to the pre-stabilized laser beam, we achieved an error point frequency noise of 100 mu Hz Hz sup - sup 1 sup / sup 2 at 100 Hz Fourier frequency. In addition we demonstrated the reliable performance of all included subsystems by several 10-hour-periods of continuous stable operation. Thus the full frequency stabilization scheme for GEO 600 was successfully tested.

  11. Experimental studies on a new highly porous hydroxyapatite matrix for obliterating open mastoid cavities.

    Science.gov (United States)

    Punke, Christoph; Zehlicke, Thorsten; Boltze, Carsten; Pau, Hans Wilhelm

    2008-09-01

    In an initial preliminary study, the applicability of a new high-porosity hydroxyapatite (HA) ceramic for obliterating large open mastoid cavities was proven and tested in an animal model (bulla of guinea pig). Experimental study. NanoBone, a highly porous matrix consisting of 76% hydroxyl apatite and 24% silicone dioxide fabricated in a sol-gel technique, was administered unilaterally into the opened bullae of 30 guinea pigs. In each animal, the opposite bulla was filled with Bio-Oss, a bone substitute consisting of a portion of mineral bovine bone. Histologic evaluations were performed 1, 2, 3, 4, 5, and 12 weeks after the implantation. After an initial phase in which the ceramic granules were surrounded by inflammatory cells (1-2 wk), there were increasing signs of vascularization. Osteoneogenesis and-at the same time-resorption of the HA ceramic were observed after the third week. No major difference in comparison to the bovine bone material could be found. Our results confirm the favorable qualities of the new ceramic reported in association with current maxillofacial literature. Conventional HA granules used for mastoid obliteration to date often showed problems with prolonged inflammatory reactions and, finally, extrusions. In contrast to those ceramics, the new material seems to induce more osteoneogenesis and undergoes early resorption probably due to its high porosity. Overall, it is similar to the bovine bone substance tested on the opposite ear in each animal. Further clinical studies may reveal whether NanoBone can be an adequate material for obliterating open mastoid cavities in patients.

  12. Stress distribution and pressure-bearing capacity of a high-pressure split-cylinder die with prism cavity

    Science.gov (United States)

    Zhao, Liang; Li, Mingzhe; Wang, Liyan; Qu, Erhu; Yi, Zhuo

    2018-03-01

    A novel high-pressure belt-type die with a split-type cylinder is investigated with respect to extending its lifetime and improving its pressure bearing capacity. Specifically, a tungsten carbide cylinder is split into several parts along the radial direction with a prism-type cavity. In this paper, the cylinders with different split numbers are chosen to study the stress distribution and compare them with the traditional belt-type die. The simulation results indicate that the split cylinder has much smaller stress than those in the belt-type cylinder, and the statistical analysis reveals that the split-pressure cylinder is able to bear higher pressure. Experimental tests also show that the high-pressure die with a split cylinder and prism cavity has a stronger pressure-bearing capacity than a belt-type die. The split cylinder has advantages of easy manufacturing, high pressure bearing capacity, and replaceable performance.

  13. Electrocatalytic oxidation of alcohols on single gold particles in highly ordered SiO2 cavities

    International Nuclear Information System (INIS)

    Li, Na; Zhou, Qun; Tian, Shu; Zhao, Hong; Li, Xiaowei; Adkins, Jason; Gu, Zhuomin; Zhao, Lili; Zheng, Junwei

    2013-01-01

    In the present work, we report a new and simple approach for preparing a highly ordered Au (1 1 1) nanoparticle (NP) array in SiO 2 cavities on indium-doped tin oxide (ITO) electrodes. We fabricated a SiO 2 cavity array on the surface of an ITO electrode using highly ordered self-assembly of polystyrene spheres as a template. Gold NPs were electrodeposited at the bottom of the SiO 2 cavities, and single gold NPs dominated with (1 1 1) facets were generated in each cavity by annealing the electrode at a high temperature. Such (1 1 1) facets were the predominate trait of the single gold particle which exhibited considerable electrocatalytic activity toward oxidation of methanol, ethanol, and glycerol. This has been attributed to the formation of incipient hydrous oxides at unusually low potential on the specific (1 1 1) facet of the gold particles. Moreover, each cavity of the SiO 2 possibly behaves as an independent electrochemical cell in which the methanol molecules are trapped; this produces an environment advantageous to catalyzing electrooxidation. The oxidation of methanol on the electrodes is a mixed control mechanism (both by diffusion and electrode kinetics). This strategy both provided an approach to study electrochemical reactions on a single particle in a microenvironment and may supply a way to construct alcohols sensors

  14. High Performance Marine Vessels

    CERN Document Server

    Yun, Liang

    2012-01-01

    High Performance Marine Vessels (HPMVs) range from the Fast Ferries to the latest high speed Navy Craft, including competition power boats and hydroplanes, hydrofoils, hovercraft, catamarans and other multi-hull craft. High Performance Marine Vessels covers the main concepts of HPMVs and discusses historical background, design features, services that have been successful and not so successful, and some sample data of the range of HPMVs to date. Included is a comparison of all HPMVs craft and the differences between them and descriptions of performance (hydrodynamics and aerodynamics). Readers will find a comprehensive overview of the design, development and building of HPMVs. In summary, this book: Focuses on technology at the aero-marine interface Covers the full range of high performance marine vessel concepts Explains the historical development of various HPMVs Discusses ferries, racing and pleasure craft, as well as utility and military missions High Performance Marine Vessels is an ideal book for student...

  15. Superconducting Radio-Frequency Cavities

    Science.gov (United States)

    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.

  16. Reduction of field emission in superconducting cavities with high power pulsed RF

    International Nuclear Information System (INIS)

    Graber, J.; Crawford, C.; Kirchgessner, J.; Padamsee, H.; Rubin, D.; Schmueser, P.

    1994-01-01

    A systematic study is presented of the effects of pulsed high power RF processing (HPP) as a method of reducing field emission (FE) in superconducting radio frequency (SRF) cavities to reach higher accelerating gradients for future particle accelerators. The processing apparatus was built to provide up to 150 kW peak RF power to 3 GHz cavities, for pulse lengths from 200 μs to 1 ms. Single-cell and nine-cell cavities were tested extensively. The thermal conductivity of the niobium for these cavities was made as high as possible to ensure stability against thermal breakdown of superconductivity. HPP proves to be a highly successful method of reducing FE loading in nine-cell SRF cavities. Attainable continuous wave (CW) fields increase by as much as 80% from their pre-HPP limits. The CW accelerating field achieved with nine-cell cavities improved from 8-15 MV/m with HPP to 14-20 MV/m. The benefits are stable with subsequent exposure to dust-free air. More importantly, HPP also proves effective against new field emission subsequently introduced by cold and warm vacuum ''accidents'' which admitted ''dirty'' air into the cavities. Clear correlations are obtained linking FE reduction with the maximum surface electric field attained during processing. In single cells the maximums reached were E peak =72 MV/m and H peak =1660 Oe. Thermal breakdown, initiated by accompanying high surface magnetic fields is the dominant limitation on the attainable fields for pulsed processing, as well as for final CW and long pulse operation. To prove that the surface magnetic field rather than the surface electric fields is the limitation to HPP effectiveness, a special two-cell cavity with a reduced magnetic to electric field ratio is successfully tested. During HPP, pulsed fields reach E peak =113 MV/m (H peak =1600 Oe) and subsequent CW low power measurement reached E peak =100 MV/m, the highest CW field ever measured in a superconducting accelerator cavity. ((orig.))

  17. Systematical study on superconducting radio frequency elliptic cavity shapes applicable to future high energy accelerators and energy recovery linacs

    Science.gov (United States)

    Shemelin, Valery; Zadeh, Shahnam Gorgi; Heller, Johann; van Rienen, Ursula

    2016-10-01

    Elliptic cavities at medium- and high-β range are receiving broader use in the particle accelerator applications. Optimizing the shape of these cavities is a complex and demanding process. In this paper we propose an optimization approach to minimize the ratio of peak magnetic field to the acceleration field Hpk/Eacc while keeping the ratio of peak surface electric field to the accelerating field Epk/Eacc, aperture radius and wall slope angle α at some permitted values. We show that it is possible to substantially vary the cavity geometry without violating the constraints or deteriorating the objective of the optimization. This gives us freedom in designing the geometry to overcome problems such as multipactor while maintaining the minimal Hpk/Eacc . The optimization is then performed to find a set of optimized geometries with minimum Hpk/Eacc for different β 's ranging from 0.4 to 1, different peak surface electric fields, wall slope angles and aperture radii. These data could be generally used as a suitable starting point in designing elliptic cavities.

  18. Systematical study on superconducting radio frequency elliptic cavity shapes applicable to future high energy accelerators and energy recovery linacs

    Directory of Open Access Journals (Sweden)

    Valery Shemelin

    2016-10-01

    Full Text Available Elliptic cavities at medium- and high-β range are receiving broader use in the particle accelerator applications. Optimizing the shape of these cavities is a complex and demanding process. In this paper we propose an optimization approach to minimize the ratio of peak magnetic field to the acceleration field H_{pk}/E_{acc} while keeping the ratio of peak surface electric field to the accelerating field E_{pk}/E_{acc}, aperture radius and wall slope angle α at some permitted values. We show that it is possible to substantially vary the cavity geometry without violating the constraints or deteriorating the objective of the optimization. This gives us freedom in designing the geometry to overcome problems such as multipactor while maintaining the minimal H_{pk}/E_{acc}. The optimization is then performed to find a set of optimized geometries with minimum H_{pk}/E_{acc} for different β’s ranging from 0.4 to 1, different peak surface electric fields, wall slope angles and aperture radii. These data could be generally used as a suitable starting point in designing elliptic cavities.

  19. Low index contrast heterostructure photonic crystal cavities with high quality factors and vertical radiation coupling

    Science.gov (United States)

    Ge, Xiaochen; Minkov, Momchil; Fan, Shanhui; Li, Xiuling; Zhou, Weidong

    2018-04-01

    We report here design and experimental demonstration of heterostructure photonic crystal cavities resonating near the Γ point with simultaneous strong lateral confinement and highly directional vertical radiation patterns. The lateral confinement is provided by a mode gap originating from a gradual modulation of the hole radii. High quality factor resonance is realized with a low index contrast between silicon nitride and quartz. The near surface-normal directional emission is preserved when the size of the core region is scaled down. The influence of the cavity size parameters on the resonant modes is also investigated theoretically and experimentally.

  20. Tunable high-power narrow-linewidth green external-cavity GaN diode laser

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system.......A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system....

  1. Flange joint system for SRF cavities utilizing high force spring clamps for low particle generation

    Science.gov (United States)

    None

    2017-09-05

    A flange joint system for SRF cavities. The flange joint system includes a set of high force spring clamps that produce high force on the simple flanges of Superconducting Radio Frequency (SRF) cavities to squeeze conventional metallic seals. The system establishes the required vacuum and RF-tight seal with minimum particle contamination to the inside of the cavity assembly. The spring clamps are designed to stay within their elastic range while being forced open enough to mount over the flange pair. Upon release, the clamps have enough force to plastically deform metallic seal surfaces and continue to a new equilibrium sprung dimension where the flanges remain held against one another with enough preload such that normal handling will not break the seal.

  2. High performance systems

    Energy Technology Data Exchange (ETDEWEB)

    Vigil, M.B. [comp.

    1995-03-01

    This document provides a written compilation of the presentations and viewgraphs from the 1994 Conference on High Speed Computing given at the High Speed Computing Conference, {open_quotes}High Performance Systems,{close_quotes} held at Gleneden Beach, Oregon, on April 18 through 21, 1994.

  3. Highly efficient generation of ultraintense high-energy ion beams using laser-induced cavity pressure acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Badziak, J.; Jablonski, S.; Raczka, P. [Institute of Plasma Physics and Laser Microfusion, Euratom Association, 01-497 Warsaw (Poland)

    2012-08-20

    Results of particle-in-cell (PIC) simulations of fast ion generation in the recently proposed laser-induced cavity pressure acceleration (LICPA) scheme in which a picosecond circularly polarized laser pulse of intensity {approx}10{sup 21} W/cm{sup 2} irradiates a carbon target placed in a cavity are presented. It is shown that due to circulation of the laser pulse in the cavity, the laser-ions energy conversion efficiency in the LICPA scheme is more than twice as high as that for the conventional (without a cavity) radiation pressure acceleration scheme and a quasi-monoenergetic carbon ion beam of the mean ion energy {approx}0.5 GeV and the energy fluence {approx}0.5 GJ/cm{sup 2} is produced with the efficiency {approx}40%. The results of PIC simulations are found to be in fairly good agreement with the predictions of the generalized light-sail model.

  4. High-flux cold rubidium atomic beam for strongly-coupled cavity QED

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Basudev [Indian Institute of Science Education and Research, Kolkata (India); University of Maryland, MD (United States); Scholten, Michael [University of Maryland, MD (United States)

    2012-08-15

    This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D{sup +} magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 10{sup 10} atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.

  5. Responsive design high performance

    CERN Document Server

    Els, Dewald

    2015-01-01

    This book is ideal for developers who have experience in developing websites or possess minor knowledge of how responsive websites work. No experience of high-level website development or performance tweaking is required.

  6. High Performance Macromolecular Material

    National Research Council Canada - National Science Library

    Forest, M

    2002-01-01

    .... In essence, most commercial high-performance polymers are processed through fiber spinning, following Nature and spider silk, which is still pound-for-pound the toughest liquid crystalline polymer...

  7. An update on the study of high-gradient elliptical SRF cavities at 805 MHz for proton and other applications

    Energy Technology Data Exchange (ETDEWEB)

    Tajima, Tsuyoshi [Los Alamos National Laboratory; Haynes, Brian [Los Alamos National Laboratory; Krawczyk, Frank [Los Alamos National Laboratory; Madrid, Mike [Los Alamos National Laboratory; Roybal, Ray [Los Alamos National Laboratory; Simakov, Evgenya [Los Alamos National Laboratory; Clemens, Bob [TJNAF; Macha, Jurt [TJNAF; Manus, Bob [TJNAF; Rimmer, Bob [TJNAF; Rimmer, Bob [TJNAF; Turlington, Larry [TJNAF

    2010-09-09

    An update on the study of 805 MHz elliptical SRF cavities that have been optimized for high gradient will be presented. An optimized cell shape, which is still appropriate for easy high pressure water rinsing, has been designed with the ratios of peak magnetic and electric fields to accelerating gradient being 3.75 mT/(MV/m) and 1.82, respectively. A total of 3 single-cell cavities have been fabricated. Two of the 3 cavities have been tested so far. The second cavity achieved an E{sub acc} of {approx}50 MV/m at Q{sub 0} of 1.4 x 10{sup 10}. This result demonstrates that 805 MHz cavities can, in principle, achieve as high as, or could even be better than, 1.3 GHz high-gradient cavities.

  8. Performance of Partial and Cavity Type Squealer Tip of a HP Turbine Blade in a Linear Cascade

    Directory of Open Access Journals (Sweden)

    Levent Kavurmacioglu

    2018-01-01

    Full Text Available Three-dimensional highly complex flow structure in tip gap between blade tip and casing leads to inefficient turbine performance due to aerothermal loss. Interaction between leakage vortex and secondary flow structures is the substantial source of that loss. Different types of squealer tip geometries were tried in the past, in order to improve turbine efficiency. The current research deals with comparison of partial and cavity type squealer tip concepts for higher aerothermal performance. Effects of squealer tip have been examined comprehensively for an unshrouded HP turbine blade tip geometry in a linear cascade. In the present paper, flow structure through the tip gap was comprehensively investigated by computational fluid dynamic (CFD methods. Numerical calculations were obtained by solving three-dimensional, incompressible, steady, and turbulent form of the Reynolds-averaged Navier-Stokes (RANS equations using a general purpose and three-dimensional viscous flow solver. The two-equation turbulence model, shear stress transport (SST, has been used. The tip profile belonging to the Pennsylvania State University Axial Flow Turbine Research Facility (AFTRF was used to create an extruded solid model of the axial turbine blade. For identifying optimal dimensions of squealer rim in terms of squealer height and squealer width, our previous studies about aerothermal investigation of cavity type squealer tip were utilized. In order to obtain the mesh, an effective parametric generation has been utilized using a multizone structured mesh. Numerical calculations indicate that partial and cavity squealer designs can be effective to reduce the aerodynamic loss and heat transfer to the blade tip. Future efforts will include novel squealer shapes for higher aerothermal performance.

  9. Intra-cavity generation of high order LGpl modes

    CSIR Research Space (South Africa)

    Ngcobo, S

    2012-08-01

    Full Text Available with the location of the Laguerre polynomial zeros. The Diffractive optical element is used to shape the TEM00 Gaussian beam and force the laser to operate on a higher order LGpl Laguerre-Gaussian modes or high order superposition of Laguerre-Gaussian modes...

  10. High-Q Defect-Free 2D Photonic Crystal Cavity from Random Localised Disorder

    Directory of Open Access Journals (Sweden)

    Kelvin Chung

    2014-07-01

    Full Text Available We propose a high-Q photonic crystal cavity formed by introducing random disorder to the central region of an otherwise defect-free photonic crystal slab (PhC. Three-dimensional finite-difference time-domain simulations determine the frequency, quality factor, Q, and modal volume, V, of the localized modes formed by the disorder. Relatively large Purcell factors of 500–800 are calculated for these cavities, which can be achieved for a large range of degrees of disorders.

  11. Entanglement dynamics of high-dimensional bipartite field states inside the cavities in dissipative environments

    Energy Technology Data Exchange (ETDEWEB)

    Tahira, Rabia; Ikram, Manzoor; Zubairy, M Suhail [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Bougouffa, Smail [Department of Physics, Faculty of Science, Taibah University, PO Box 30002, Madinah (Saudi Arabia)

    2010-02-14

    We investigate the phenomenon of sudden death of entanglement in a high-dimensional bipartite system subjected to dissipative environments with an arbitrary initial pure entangled state between two fields in the cavities. We find that in a vacuum reservoir, the presence of the state where one or more than one (two) photons in each cavity are present is a necessary condition for the sudden death of entanglement. Otherwise entanglement remains for infinite time and decays asymptotically with the decay of individual qubits. For pure two-qubit entangled states in a thermal environment, we observe that sudden death of entanglement always occurs. The sudden death time of the entangled states is related to the number of photons in the cavities, the temperature of the reservoir and the initial preparation of the entangled states.

  12. Entanglement dynamics of high-dimensional bipartite field states inside the cavities in dissipative environments

    International Nuclear Information System (INIS)

    Tahira, Rabia; Ikram, Manzoor; Zubairy, M Suhail; Bougouffa, Smail

    2010-01-01

    We investigate the phenomenon of sudden death of entanglement in a high-dimensional bipartite system subjected to dissipative environments with an arbitrary initial pure entangled state between two fields in the cavities. We find that in a vacuum reservoir, the presence of the state where one or more than one (two) photons in each cavity are present is a necessary condition for the sudden death of entanglement. Otherwise entanglement remains for infinite time and decays asymptotically with the decay of individual qubits. For pure two-qubit entangled states in a thermal environment, we observe that sudden death of entanglement always occurs. The sudden death time of the entangled states is related to the number of photons in the cavities, the temperature of the reservoir and the initial preparation of the entangled states.

  13. A highly directive graphene antenna embedded inside a Fabry-Perot cavity in terahertz regime

    Science.gov (United States)

    Roshanaei, Majid; Karami, Hamidreza; Dehkhoda, Parisa; Esfahani, Hamid; Dabir, Fatemeh

    2018-05-01

    In this paper, a highly directive nano-thickness graphene-based antenna is introduced in the terahertz frequency band. The antenna is a graphene patch dipole which is placed between two Bragg mirrors called Fabry-Perot cavity. Tunability of the graphene's conductivity makes it possible to excite the desired resonances of the cavity. Here, first, a single resonant antenna is introduced at 5 THz with an enhanced gain from 2.11 dBi to 12.8 dBi with a beamwidth of 22.7°. Then, a triple resonant antenna at 4.7, 5 and 5.3 THz is presented with respective gains of 7.97, 11.9 and 8.52 dBi. Finally, the effect of dimensions and number of the dielectric layers of the cavity are studied in order to further increase in directivity.

  14. High stable electro-optical cavity-dumped Nd:YAG laser

    International Nuclear Information System (INIS)

    Ma, Y F; Yu, X; Zhang, J W; Li, H

    2012-01-01

    In this paper, an electro-optical cavity-dumped 10 Hz Nd:Y 3 Al 5 O 12 (Nd:YAG) laser was demonstrated. We designed an optimized high stable concavo-convex cavity according to the thermal-insensitive theory that the cavity could be deep stable and be insensitive to the change of thermal lens of laser crystal when g 1 *g 2 = 1/2. The output pulse width was constant at 6.0±0.1 ns. The maximum output energy was 40 mJ. The laser had outstanding stability of output characteristics. The fluctuations of average output energy and divergence angle within 8 cycles were 1.24% and 0.06 mrad, respectively

  15. Study of cavity effect in micro-Pirani gauge chamber with improved sensitivity for high vacuum regime

    Directory of Open Access Journals (Sweden)

    Guohe Zhang

    2018-05-01

    Full Text Available Ultra-low pressure application of Pirani gauge needs significant improvement of sensitivity and expansion of measureable low pressure limit. However, the performance of Pirani gauge in high vacuum regime remains critical concerns since gaseous thermal conduction with high percentage is essential requirement. In this work, the heat transfer mechanism of micro-Pirani gauge packaged in a non-hermetic chamber was investigated and analyzed compared with the one before wafer-level packaging. The cavity effect, extremely important for the efficient detection of low pressure, was numerically and experimentally analyzed considering the influence of the pressure, the temperature and the effective heat transfer area in micro-Pirani gauge chamber. The thermal conduction model is validated by experiment data of MEMS Pirani gauges with and without capping. It is found that nature gaseous convection in chamber, determined by the Rayleigh number, should be taken into consideration. The experiment and model calculated results show that thermal resistance increases in the molecule regime, and further increases after capping due to the suppression of gaseous convection. The gaseous thermal conduction accounts for an increasing percentage of thermal conduction at low pressure while little changes at high pressure after capping because of the existence of cavity effect improving the sensitivity of cavity-effect-influenced Pirani gauge for high vacuum regime.

  16. Hypertrophic Cardiomyopathy Associated with Mid-cavity Obstruction and High Left Intraventricular Pressure

    Science.gov (United States)

    A. Bejiqi, Ramush; J. Retkoceri, Ragip; Sh. Bejiqi, Hana

    2011-01-01

    We report a case of a child, with a rare form of the idiopathic hypertrophic cardiomyopathy, associated with mid-cavity obstruction and high intraventricular peak pressure. Cardiomyopathy, diagnosed antenataly, was followed postnataly and, despite of a lot echocardiographic findings - the growing, development and clinical signs are minimal. PMID:23407799

  17. Hypertrophic Cardiomyopathy Associated with Mid-cavity Obstruction and High Left Intraventricular Pressure

    OpenAIRE

    A. Bejiqi, Ramush; J. Retkoceri, Ragip; Sh. Bejiqi, Hana

    2011-01-01

    We report a case of a child, with a rare form of the idiopathic hypertrophic cardiomyopathy, associated with mid-cavity obstruction and high intraventricular peak pressure. Cardiomyopathy, diagnosed antenataly, was followed postnataly and, despite of a lot echocardiographic findings - the growing, development and clinical signs are minimal.

  18. Development of a high-resolution cavity-beam position monitor

    Directory of Open Access Journals (Sweden)

    Yoichi Inoue

    2008-06-01

    Full Text Available We have developed a high-resolution cavity-beam position monitor (BPM to be used at the focal point of the ATF2, which is a test beam line that is now being built to demonstrate stable orbit control at ∼nanometer resolution. The design of the cavity structure was optimized for the Accelerator Test Facility (ATF beam in various ways. For example, the cavity has a rectangular shape in order to isolate two dipole modes in orthogonal directions, and a relatively thin gap that is less sensitive to trajectory inclination. A two stage homodyne mixer with highly sensitive electronics and phase-sensitive detection was also developed. Two BPM blocks, each containing two cavity BPMs, were installed in the existing ATF beam line using a rigid support frame. After testing the basic characteristics, we measured the resolution using three BPMs. The system demonstrated 8.7 nm position resolution over a dynamic range of 5  μm.

  19. Clojure high performance programming

    CERN Document Server

    Kumar, Shantanu

    2013-01-01

    This is a short, practical guide that will teach you everything you need to know to start writing high performance Clojure code.This book is ideal for intermediate Clojure developers who are looking to get a good grip on how to achieve optimum performance. You should already have some experience with Clojure and it would help if you already know a little bit of Java. Knowledge of performance analysis and engineering is not required. For hands-on practice, you should have access to Clojure REPL with Leiningen.

  20. accelerating cavity from LEP

    CERN Multimedia

    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.

  1. High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Traian Oneţ

    2009-01-01

    Full Text Available The paper presents the last studies and researches accomplished in Cluj-Napoca related to high performance concrete, high strength concrete and self compacting concrete. The purpose of this paper is to raid upon the advantages and inconveniences when a particular concrete type is used. Two concrete recipes are presented, namely for the concrete used in rigid pavement for roads and another one for self-compacting concrete.

  2. High performance polymeric foams

    International Nuclear Information System (INIS)

    Gargiulo, M.; Sorrentino, L.; Iannace, S.

    2008-01-01

    The aim of this work was to investigate the foamability of high-performance polymers (polyethersulfone, polyphenylsulfone, polyetherimide and polyethylenenaphtalate). Two different methods have been used to prepare the foam samples: high temperature expansion and two-stage batch process. The effects of processing parameters (saturation time and pressure, foaming temperature) on the densities and microcellular structures of these foams were analyzed by using scanning electron microscopy

  3. High-efficiency cavity-dumped micro-chip Yb:YAG laser

    Science.gov (United States)

    Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

    2014-09-01

    High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

  4. [Investigation of a new highly porous hydroxyapatite matrix for obliterating open mastoid cavities - application in guinea pigs bulla].

    Science.gov (United States)

    Punke, C; Zehlicke, T; Boltze, C; Pau, H W

    2009-04-01

    Many different techniques for obliterating open mastoid cavity have been described. The results after the application of alloplastic materials like Hydroxyapatite and Tricalciumphosphate were poor due to long-lasting resorption. Extrusion of those materials has been described. We investigated the applicability of a new high-porosity ceramic for obliterating large open mastoid cavities and tested it in an animal model (bulla of guinea pig). A highly porous matrix (NanoBone) bone-inductor fabricated in a sol-gel-technique was administered unilaterally into the opened bullae of 30 guinea pigs. In each animal the opposite bulla was filled with Bio-Oss, a bone substitute consisting of a portion of mineral bovine bone. Histological evaluations were performed 1, 2, 3, 4, 5 and 12 weeks after the implantation. After the initial phase with an inflammatory reaction creating a loose granulation tissue, we observed the formation of trabeculare bone within the fourth week in both groups. From the fifth week on we found osteoclasts on the surface of NanoBone and Bio-Oss with consecutive degradation of both materials. In our animal model study we found beneficial properties of the used bone-inductors NanoBone and Bio-Oss for obliterating open mastoid cavities.

  5. Analysis of the cool down related cavity performance of the European XFEL vertical acceptance tests

    Energy Technology Data Exchange (ETDEWEB)

    Wenskat, Marc; Schaffran, J.

    2017-09-15

    For the European X-Ray Free Electron Laser (XFEL) cavity production, the cold radio-frequency (RF) test of the cavities at 2 K after delivery from the two vendors was the mandatory acceptance test. It has been previously reported, that the cool down dynamics of a cavity across T{sub c} has a significant influence on the observed intrinsic quality factor Q{sub 0}, which is a measure of the losses on the inner cavity surface. A total number of 367 cool downs is used to analyze this correlation and we show that such a correlation is not observed during the European XFEL cavity production.

  6. High performance conductometry

    International Nuclear Information System (INIS)

    Saha, B.

    2000-01-01

    Inexpensive but high performance systems have emerged progressively for basic and applied measurements in physical and analytical chemistry on one hand, and for on-line monitoring and leak detection in plants and facilities on the other. Salient features of the developments will be presented with specific examples

  7. Danish High Performance Concretes

    DEFF Research Database (Denmark)

    Nielsen, M. P.; Christoffersen, J.; Frederiksen, J.

    1994-01-01

    In this paper the main results obtained in the research program High Performance Concretes in the 90's are presented. This program was financed by the Danish government and was carried out in cooperation between The Technical University of Denmark, several private companies, and Aalborg University...... concretes, workability, ductility, and confinement problems....

  8. High performance homes

    DEFF Research Database (Denmark)

    Beim, Anne; Vibæk, Kasper Sánchez

    2014-01-01

    . Consideration of all these factors is a precondition for a truly integrated practice and as this chapter demonstrates, innovative project delivery methods founded on the manufacturing of prefabricated buildings contribute to the production of high performance homes that are cost effective to construct, energy...

  9. New generation of one-dimensional photonic crystal cavities as robust high-efficient frequency converter

    Science.gov (United States)

    Parvini, T. S.; Tehranchi, M. M.; Hamidi, S. M.

    2017-07-01

    An effective method is proposed to design finite one-dimensional photonic crystal cavities (PhCCs) as robust high-efficient frequency converter. For this purpose, we consider two groups of PhCCs which are constructed by stacking m nonlinear (LiNbO3) and n linear (air) layers with variable thicknesses. In the first group, the number of linear layers is less than the nonlinear layers by one and in the second group by two. The conversion efficiency is calculated as a function of the arrangement and thicknesses of the linear and nonlinear layers by benefiting from nonlinear transfer matrix method. Our numerical simulations show that for each group of PhCCs, there is a structural formula by which the configurations with the highest efficiency can be constructed for any values of m and n (i.e. any number of layers). The efficient configurations are equivalent to Fabry-Pérot cavities that depend on the relationship between m and n and the mirrors in two sides of these cavities can be periodic or nonperiodic. The conversion efficiencies of these designed PhCCs are more than 5 orders of magnitude higher than the perfect ones which satisfy photonic bandgap edge and quasi-phase matching. Moreover, the results reveal that conversion efficiencies of Fabry-Pérot cavities with non-periodic mirrors are one order of magnitude higher than those with periodic mirrors. The major physical mechanisms of the enhancement are quasi-phase matching effect, cavity effect induced by dispersive mirrors, and double resonance for the pump and the harmonic fields in defect state. We believe that this method is very beneficial to the design of high-efficient compact optical frequency converters.

  10. LLRF Control of High Loaded-Q Cavities for the LCLS-II

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Carlos [LBNL, Berkeley; Babel, Sandeep [SLAC; Bachimanchi, Ramakrishna [Jefferson Lab; Boyes, Matt [SLAC; Chase, Brian [Fermilab; Cullerton, Ed [Fermilab; Doolittle, Lawrence [LBNL, Berkeley; Einstein, Joshua [Fermilab; Hong, Bo [SLAC; Hovater, Curt [Jefferson Lab; Huang, Gang [LBNL, Berkeley; Ratti, Alessandro [LBNL, Berkeley

    2016-06-01

    The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW Superconducting Radio Frequency (SCRF) linac. The nature of the machine places stringent requirements in the Low-Level RF (LLRF) system, expected to control the cavity fields within 0.01 degrees in phase and 0.01% in amplitude, which is equivalent to a longitudinal motion of the cavity structure in the nanometer range. This stability has been achieved in the past but never for hundreds of superconducting cavities in Continuous-Wave (CW) operation. The difficulty resides in providing the ability to reject disturbances from the cryomodule, which is incompletely known as it depends on the cryomodule structure itself (currently under development at JLab and Fermilab) and the harsh accelerator environment. Previous experience in the field and an extrapolation to the cavity design parameters (relatively high Q_{L}c≈ 4×10⁷ , implying a half-bandwidth of around 16 Hz) suggest the use of strong RF feedback to reject the projected noise disturbances, which in turn demands careful engineering of the entire system.

  11. Model for initiation of quality factor degradation at high accelerating fields in superconducting radio-frequency cavities

    International Nuclear Information System (INIS)

    Dzyuba, A; Romanenko, A; Cooley, L D

    2010-01-01

    A model for the onset of the reduction in superconducting radio-frequency (SRF) cavity quality factor, the so-called Q-drop, at high accelerating electric fields is presented. Since magnetic fields at the cavity equator are tied to accelerating electric fields by a simple geometric factor, the onset of magnetic flux penetration determines the onset of Q-drop. We consider breakdown of the surface barrier at triangular grooves to predict the magnetic field of first flux penetration H pen . Such defects were argued to be the worst case by Buzdin and Daumens (1998 Physica C 294 257), whose approach, moreover, incorporates both the geometry of the groove and local contamination via the Ginzburg-Landau parameter κ. Since previous Q-drop models focused on either topography or contamination alone, the proposed model allows new comparisons of one effect in relation to the other. The model predicts equivalent reduction of H pen when either roughness or contamination were varied alone, so smooth but dirty surfaces limit cavity performance about as much as rough but clean surfaces do. Still lower H pen was predicted when both effects were combined, i.e. contamination should exacerbate the negative effects of roughness and vice versa. To test the model with actual data, coupons were prepared by buffered chemical polishing and electropolishing, and stylus profilometry was used to obtain distributions of angles. From these data, curves for surface resistance generated by simple flux flow as a function of magnetic field were generated by integrating over the distribution of angles for reasonable values of κ. This showed that combined effects of roughness and contamination indeed reduce the Q-drop onset field by ∼ 20%, and that contamination contributes to Q-drop as much as roughness. The latter point may be overlooked by SRF cavity research, since access to the cavity interior by spectroscopy tools is very difficult, whereas optical images have become commonplace. The model

  12. Model for initiation of quality factor degradation at high accelerating fields in superconducting radio-frequency cavities

    Science.gov (United States)

    Dzyuba, A.; Romanenko, A.; Cooley, L. D.

    2010-12-01

    A model for the onset of the reduction in superconducting radio-frequency (SRF) cavity quality factor, the so-called Q-drop, at high accelerating electric fields is presented. Since magnetic fields at the cavity equator are tied to accelerating electric fields by a simple geometric factor, the onset of magnetic flux penetration determines the onset of Q-drop. We consider breakdown of the surface barrier at triangular grooves to predict the magnetic field of first flux penetration Hpen. Such defects were argued to be the worst case by Buzdin and Daumens (1998 Physica C 294 257), whose approach, moreover, incorporates both the geometry of the groove and local contamination via the Ginzburg-Landau parameter κ. Since previous Q-drop models focused on either topography or contamination alone, the proposed model allows new comparisons of one effect in relation to the other. The model predicts equivalent reduction of Hpen when either roughness or contamination were varied alone, so smooth but dirty surfaces limit cavity performance about as much as rough but clean surfaces do. Still lower Hpen was predicted when both effects were combined, i.e. contamination should exacerbate the negative effects of roughness and vice versa. To test the model with actual data, coupons were prepared by buffered chemical polishing and electropolishing, and stylus profilometry was used to obtain distributions of angles. From these data, curves for surface resistance generated by simple flux flow as a function of magnetic field were generated by integrating over the distribution of angles for reasonable values of κ. This showed that combined effects of roughness and contamination indeed reduce the Q-drop onset field by ~ 20%, and that contamination contributes to Q-drop as much as roughness. The latter point may be overlooked by SRF cavity research, since access to the cavity interior by spectroscopy tools is very difficult, whereas optical images have become commonplace. The model was

  13. 1.3 GHz superconducting RF cavity program at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Ginsburg, C.M.; Arkan, T.; Barbanotti, S.; Carter, H.; Champion, M.; Cooley, L.; Cooper, C.; Foley, M.; Ge, M.; Grimm, C.; Harms, E.; /Fermilab

    2011-03-01

    At Fermilab, 9-cell 1.3 GHz superconducting RF (SRF) cavities are prepared, qualified, and assembled into cryomodules (CMs) for Project X, an International Linear Collider (ILC), or other future projects. The 1.3 GHz SRF cavity program includes targeted R&D on 1-cell 1.3 GHz cavities for cavity performance improvement. Production cavity qualification includes cavity inspection, surface processing, clean assembly, and one or more cryogenic low-power CW qualification tests which typically include performance diagnostics. Qualified cavities are welded into helium vessels and are cryogenically tested with pulsed high-power. Well performing cavities are assembled into cryomodules for pulsed high-power testing in a cryomodule test facility, and possible installation into a beamline. The overall goals of the 1.3 GHz SRF cavity program, supporting facilities, and accomplishments are described.

  14. Resonant excitation of high order modes in the 3.9 GHz cavity of the Linac Coherent Light Source

    Science.gov (United States)

    Lunin, A.; Khabiboulline, T.; Solyak, N.; Sukhanov, A.; Yakovlev, V.

    2018-02-01

    Construction of the Linac Coherent Light Source II (LCLS-II) is underway for the world's first hard x-ray free-electron laser. A central part of the LCLS-II project is a 4 GeV superconducting radio frequency electron linac that will operate in the continuous wave (cw) mode. The linac is segmented into four sections named as L 0 , L 1 , L 2 , and L 3 . Two 3.9 GHz cryomodules, each housing of eight third-harmonic cavities similar to the cavities developed for the European X-ray Free Electron Laser (XFEL), will be used in section L 1 of the linac for linearizing the longitudinal beam profile. In this paper, we present a study of trapped high order modes (HOMs) excited by a cw electron beam in the third-harmonic cavities of the LCLS-II linac. A detailed comparison of the original XFEL design and the LCLS-II design with a modified end group is performed in order to estimate the effect of a reduced beam pipe aperture on the efficiency of HOM damping. Furthermore, we apply a statistical analysis of the eigenmode spectrum for the estimation of the probability of resonant HOM losses and influence of HOMs on beam dynamics.

  15. High-Performance Networking

    CERN Multimedia

    CERN. Geneva

    2003-01-01

    The series will start with an historical introduction about what people saw as high performance message communication in their time and how that developed to the now to day known "standard computer network communication". It will be followed by a far more technical part that uses the High Performance Computer Network standards of the 90's, with 1 Gbit/sec systems as introduction for an in depth explanation of the three new 10 Gbit/s network and interconnect technology standards that exist already or emerge. If necessary for a good understanding some sidesteps will be included to explain important protocols as well as some necessary details of concerned Wide Area Network (WAN) standards details including some basics of wavelength multiplexing (DWDM). Some remarks will be made concerning the rapid expanding applications of networked storage.

  16. High-Q AlAs/GaAs adiabatic micropillar cavities with submicron diameters for cQED experiments

    DEFF Research Database (Denmark)

    Lermer, M.; Gregersen, Niels; Dunzer, F.

    Quantum dot (QD) micropillar cavities represent an interesting class of microresonator systems aiming at the observation and application of cavity quantum electrodynamics (cQED) on a semiconductor platform. They combine valuable properties i.e. a highly directional and approximately Gaussian shaped...

  17. Noise Performance of a 72 m Suspended FABRY-PÉROT Cavity

    Science.gov (United States)

    Dumas, Jean-Charles; Ju, Li; Barriga, Pablo; Zhao, Chunnong; Woolley, Andrew A.; Blair, David G.

    We report on a seismic isolator with a relatively compact 3 m stack, combining new passive isolation techniques. It consists of three cascaded passive 3D isolator stages suspended from an Ultra Low Frequency (ULF) horizontal Robert linkage stage which itself is suspended from a ULF 3D pre-isolator. The 3D isolators use self-damping pendulums and Euler springs for the horizontal and vertical stages respectively, while the 3D pre-isolator is the combination of an inverse pendulum which provides low frequency horizontal pre-isolation, and a LaCoste linkage for low frequency vertical pre-isolation. Two isolators suspending mirror test masses have been built to form a 72 m optical cavity in order to test their performance. We report results which demonstrate residual motion at nanometer level at frequencies above 1 Hz.

  18. Automated detection of cavities present in the high explosive filler of artillery shells

    International Nuclear Information System (INIS)

    Kruger, R.P.; Janney, D.H.; Breedlove, J.R. Jr.

    1976-01-01

    Initial research has been conducted into the use of digital image analysis techniques for automated detection and characterization of piping cavities present in the high explosive (HE) filler region of 105-mm artillery shells. Experimental work utilizing scene segmentation techniques followed by a sequential similarity detection algorithm for cavitation detection have yielded promising initial results. This work is described with examples of computer-detected defects

  19. High performance data transfer

    Science.gov (United States)

    Cottrell, R.; Fang, C.; Hanushevsky, A.; Kreuger, W.; Yang, W.

    2017-10-01

    The exponentially increasing need for high speed data transfer is driven by big data, and cloud computing together with the needs of data intensive science, High Performance Computing (HPC), defense, the oil and gas industry etc. We report on the Zettar ZX software. This has been developed since 2013 to meet these growing needs by providing high performance data transfer and encryption in a scalable, balanced, easy to deploy and use way while minimizing power and space utilization. In collaboration with several commercial vendors, Proofs of Concept (PoC) consisting of clusters have been put together using off-the- shelf components to test the ZX scalability and ability to balance services using multiple cores, and links. The PoCs are based on SSD flash storage that is managed by a parallel file system. Each cluster occupies 4 rack units. Using the PoCs, between clusters we have achieved almost 200Gbps memory to memory over two 100Gbps links, and 70Gbps parallel file to parallel file with encryption over a 5000 mile 100Gbps link.

  20. A global high-resolution data set of ice sheet topography, cavity geometry and ocean bathymetry

    DEFF Research Database (Denmark)

    Schaffer, Janin; Timmermann, Ralph; Arndt, Jan Erik

    2016-01-01

    of the Southern Ocean (IBCSO) version 1. While RTopo-1 primarily aimed at a good and consistent representation of the Antarctic ice sheet, ice shelves, and sub-ice cavities, RTopo-2now also contains ice topographies of the Greenland ice sheet and outlet glaciers. In particular, we aimed at agood representation....... For the continental shelf off Northeast Greenland and the floating ice tongue of Nioghalvfjerdsfjorden Glacier at about79 N, we incorporated a high-resolution digital bathymetry model considering original multibeam survey datafor the region. Radar data for surface topographies of the floating ice tongues...... for the geometry of Getz, Abbot, andFimbul ice shelf cavities. The data set is available in full and in regional subsets in NetCDF format from thePANGAEA database at doi:10.1594/PANGAEA.856844....

  1. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    Science.gov (United States)

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions.

  2. High-dose-rate brachytherapy using molds for oral cavity cancer. The technique and its limitations

    International Nuclear Information System (INIS)

    Nishimura, Yasumasa; Yokoe, Yoshihiko; Nagata, Yasushi; Okajima, Kaoru; Nishida, Mitsuo; Hiraoka, Masahiro

    1998-01-01

    With the availability of a high-dose-rate (HDR) remote afterloading device, a Phase I/II protocol was initiated at our institution to assess the toxicity and efficacy of HDR intracavitary brachytherapy, using molds, in the treatment of squamous cell carcinomas of the oral cavity. Eight patients with squamous cell carcinoma of the oral cavity were treated by the technique. The primary sites of the tumors were the buccal mucosa, oral floor, and gingiva. Two of the buccal mucosal cancers were located in the retromolar trigon. For each patient, a customized mold was fabricated, in which two to four afterloading catheters were placed for an 192 Ir HDR source. Four to seven fractions of 3-4 Gy, 5 mm below the mold surface, were given following external radiation therapy of 40-60 Gy/ 2 Gy. The total dose of HDR brachytherapy ranged from 16 to 28Gy. Although a good initial complete response rate of 7/8 (88%) was achieved, there was local recurrence in four of these seven patients. Both of the retromolar trigon tumors showed marginal recurrence. No serious (e.g., ulcer or bone exposure) late radiation damage has been observed thus far in the follow up period of 15-57 months. High-dose-rate brachytherapy using the mold technique seems a safe and useful method for selected early and superficial oral cavity cancer. However, it is not indicated for thick tumors and/or tumors located in the retromolar trigon. (author)

  3. Single-mode temperature and polarisation-stable high-speed 850nm vertical cavity surface emitting lasers

    International Nuclear Information System (INIS)

    Nazaruk, D E; Blokhin, S A; Maleev, N A; Bobrov, M A; Pavlov, M M; Kulagina, M M; Vashanova, K A; Zadiranov, Yu M; Ustinov, V M; Kuzmenkov, A G; Vasil'ev, A P; Gladyshev, A G; Blokhin, A A; Salut, 7 Larina Str, N Novgorod, 603950 (Russian Federation))" data-affiliation=" (JSV Salut, 7 Larina Str, N Novgorod, 603950 (Russian Federation))" >Fefelov, A G

    2014-01-01

    A new intracavity-contacted design to realize temperature and polarization-stable high-speed single-mode 850 nm vertical cavity surface emitting lasers (VCSELs) grown by molecular-beam epitaxy is proposed. Temperature dependences of static and dynamic characteristics of the 4.5 pm oxide aperture InGaAlAs VCSEL were investigated in detail. Due to optimal gain-cavity detuning and enhanced carrier localization in the active region the threshold current remains below 0.75 mA for the temperature range within 20-90°C, while the output power exceeds 1 mW up to 90°C. Single-mode operation with side-mode suppression ratio higher than 30 dB and orthogonal polarization suppression ratio more than 18 dB was obtained in the whole current and temperature operation range. Device demonstrates serial resistance less than 250 Ohm, which is rather low for any type of single-mode short- wavelength VCSELs. VCSEL demonstrates temperature robust high-speed operation with modulation bandwidth higher than 13 GHz in the entire temperature range of 20-90°C. Despite high resonance frequency the high-speed performance of developed VCSELs was limited by the cut-off frequency of the parasitic low pass filter created by device resistances and capacitances. The proposed design is promising for single-mode high-speed VCSEL applications in a wide spectral range

  4. Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

    Science.gov (United States)

    Liu, Bo; Braiman, Yehuda

    2018-05-01

    We introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ∼25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. We found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

  5. High performance sapphire windows

    Science.gov (United States)

    Bates, Stephen C.; Liou, Larry

    1993-02-01

    High-quality, wide-aperture optical access is usually required for the advanced laser diagnostics that can now make a wide variety of non-intrusive measurements of combustion processes. Specially processed and mounted sapphire windows are proposed to provide this optical access to extreme environment. Through surface treatments and proper thermal stress design, single crystal sapphire can be a mechanically equivalent replacement for high strength steel. A prototype sapphire window and mounting system have been developed in a successful NASA SBIR Phase 1 project. A large and reliable increase in sapphire design strength (as much as 10x) has been achieved, and the initial specifications necessary for these gains have been defined. Failure testing of small windows has conclusively demonstrated the increased sapphire strength, indicating that a nearly flawless surface polish is the primary cause of strengthening, while an unusual mounting arrangement also significantly contributes to a larger effective strength. Phase 2 work will complete specification and demonstration of these windows, and will fabricate a set for use at NASA. The enhanced capabilities of these high performance sapphire windows will lead to many diagnostic capabilities not previously possible, as well as new applications for sapphire.

  6. Clinical outcome of high-dose-rate interstitial brachytherapy in patients with oral cavity cancer

    International Nuclear Information System (INIS)

    Lee, Sung Uk; Cho, Kwan Ho; Moon, Sung Ho; Choi, Sung Weon; Park, Joo Yong; Yun, Tak; Lee, Sang Hyun; Lim, Young Kyung; Jeong, Chi Young

    2014-01-01

    To evaluate the clinical outcome of high-dose-rate (HDR) interstitial brachytherapy (IBT) in patients with oral cavity cancer. Sixteen patients with oral cavity cancer treated with HDR remote-control afterloading brachytherapy using 192Ir between 2001 and 2013 were analyzed retrospectively. Brachytherapy was administered in 11 patients as the primary treatment and in five patients as salvage treatment for recurrence after the initial surgery. In 12 patients, external beam radiotherapy (50-55 Gy/25 fractions) was combined with IBT of 21 Gy/7 fractions. In addition, IBT was administered as the sole treatment in three patients with a total dose of 50 Gy/10 fractions and as postoperative adjuvant treatment in one patient with a total of 35 Gy/7 fractions. The 5-year overall survival of the entire group was 70%. The actuarial local control rate after 3 years was 84%. All five recurrent cases after initial surgery were successfully salvaged using IBT +/- external beam radiotherapy. Two patients developed local recurrence at 3 and 5 months, respectively, after IBT. The acute complications were acceptable (< or =grade 2). Three patients developed major late complications, such as radio-osteonecrosis, in which one patient was treated by conservative therapy and two required surgical intervention. HDR IBT for oral cavity cancer was effective and acceptable in diverse clinical settings, such as in the cases of primary or salvage treatment.

  7. On-chip spectroscopy with thermally tuned high-Q photonic crystal cavities

    Energy Technology Data Exchange (ETDEWEB)

    Liapis, Andreas C., E-mail: andreas.liapis@gmail.com; Gao, Boshen; Siddiqui, Mahmudur R. [The Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Shi, Zhimin [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States); Boyd, Robert W. [The Institute of Optics, University of Rochester, Rochester, New York 14627 (United States); Department of Physics and School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada)

    2016-01-11

    Spectroscopic methods are a sensitive way to determine the chemical composition of potentially hazardous materials. Here, we demonstrate that thermally tuned high-Q photonic crystal cavities can be used as a compact high-resolution on-chip spectrometer. We have used such a chip-scale spectrometer to measure the absorption spectra of both acetylene and hydrogen cyanide in the 1550 nm spectral band and show that we can discriminate between the two chemical species even though the two materials have spectral features in the same spectral region. Our results pave the way for the development of chip-size chemical sensors that can detect toxic substances.

  8. Effects of finite temperature on two-photon transitions in a Rydberg atom in a high-Q cavity

    International Nuclear Information System (INIS)

    Puri, R.R.; Joshi, A.

    1989-01-01

    The effects of cavity temperature on an effective two-level atom undergoing two-photon transitions in a high-Q cavity are investigated. The quantum statistical properties of the field and the dynamical properties of the atom in this case are studied and compared with those for an atom making one-photon transitions between the two levels. The analysis is based on the solution of the equation for the density matrix in the secular approximation which is known to be a valid approximation in the case of a Rydberg atom in a high-Q cavity. (orig.)

  9. Terahertz gas sensing based on a simple one-dimensional photonic crystal cavity with high-quality factors

    DEFF Research Database (Denmark)

    Chen, T.; Han, Z. H.; Liu, J. J.

    2014-01-01

    We report in this paper terahertz gas sensing using a simple 1D photonic crystal cavity. The resonant frequencies of the cavity depend linearly on the refractive index of the ambient gas, which can then be measured by monitoring the resonance shift. Although quite easy to manufacture, this cavity...... exhibits high-quality factors, facilitating the realization of high sensitivity in the gas refractive index sensing. In our experiment, 6% of the change of hydrogen concentration in air, which corresponds to a refractive index change of 1.4 x 10(-5), can be steadily detected, and different gas samples can...

  10. Storage of laser pulses in a Fabry-Perot optical cavity for high flux x-ray

    International Nuclear Information System (INIS)

    Takezawa, K.; Honda, Y.; Sasao, N.; Araki, S.; Higashi, Y.; Taniguchi, T.; Urakawa, J.; Nomura, M.; Sakai, H.

    2004-01-01

    We have a plan to produce a high flux x-ray for medical use by using a Fabry-Perot optical cavity in which the lower pulses from a mode-locked laser are stored and enhanced. In this plan, the X-ray is produced from the Compton scattering of electrons in a storage ring with the laser light in the optical cavity. In order to increase X-ray flux, high power laser light is necessary. We show the enhancement of the laser power from the model locked laser with a Fabry-Perot optical cavity. (author)

  11. Transparent Nanopore Cavity Arrays Enable Highly Parallelized Optical Studies of Single Membrane Proteins on Chip.

    Science.gov (United States)

    Diederichs, Tim; Nguyen, Quoc Hung; Urban, Michael; Tampé, Robert; Tornow, Marc

    2018-06-13

    Membrane proteins involved in transport processes are key targets for pharmaceutical research and industry. Despite continuous improvements and new developments in the field of electrical readouts for the analysis of transport kinetics, a well-suited methodology for high-throughput characterization of single transporters with nonionic substrates and slow turnover rates is still lacking. Here, we report on a novel architecture of silicon chips with embedded nanopore microcavities, based on a silicon-on-insulator technology for high-throughput optical readouts. Arrays containing more than 14 000 inverted-pyramidal cavities of 50 femtoliter volumes and 80 nm circular pore openings were constructed via high-resolution electron-beam lithography in combination with reactive ion etching and anisotropic wet etching. These cavities feature both, an optically transparent bottom and top cap. Atomic force microscopy analysis reveals an overall extremely smooth chip surface, particularly in the vicinity of the nanopores, which exhibits well-defined edges. Our unprecedented transparent chip design provides parallel and independent fluorescent readout of both cavities and buffer reservoir for unbiased single-transporter recordings. Spreading of large unilamellar vesicles with efficiencies up to 96% created nanopore-supported lipid bilayers, which are stable for more than 1 day. A high lipid mobility in the supported membrane was determined by fluorescent recovery after photobleaching. Flux kinetics of α-hemolysin were characterized at single-pore resolution with a rate constant of 0.96 ± 0.06 × 10 -3 s -1 . Here, we deliver an ideal chip platform for pharmaceutical research, which features high parallelism and throughput, synergistically combined with single-transporter resolution.

  12. A Family of L-band SRF Cavities for High Power Proton Driver Applications

    International Nuclear Information System (INIS)

    Rimmer, Robert; Marhauser, Frank

    2009-01-01

    Recent global interest in high duty factor or CW superconducting linacs with high average beam power highlights the need for robust and reliable SRF structures capable of delivering high average RF power to the beam with moderate HOM damping, low interception of halo and good efficiency. Potential applications include proton or H- drivers for spallation neutron sources, neutrino physics, waste transmutation, subcritical reactors, and high-intensity high-energy physics experiments. We describe a family of SRF cavities with a range of Betas capable of transporting beam currents in excess of 10 mA CW with large irises for minimal interception of halo and HOM and power couplers capable of supporting high average power operation. Goals include an efficient cell shape, high packing factor for efficient real-estate gradient and strong HOM damping to ensure stable beam operation,

  13. Modeling study on the thermal performance of a modified cavity receiver with glass window and secondary reflector

    International Nuclear Information System (INIS)

    Chang, Huawei; Duan, Chen; Wen, Ke; Liu, Yuting; Xiang, Can; Wan, Zhongmin; He, Sinian; Jing, Changwei; Shu, Shuiming

    2015-01-01

    Highlights: • A modified cavity receiver with glass window and secondary reflector is presented. • Optical and thermal performance of the modified cavity receiver is investigated. • Effects of glass window and secondary reflector are analyzed with comparison study. - Abstract: The development of a cavity receiver for a 1 kW beta type solar Stirling engine is presented in this work. The proposed receiver is composed of an additional quartz glass window and a secondary reflector aiming at improving the thermal performance. Monte-Carlo ray-tracing method is adopted to study the optical property and calculate radiative exchange factors of the solar collector system. The results show that the radiation flux sent to the proposed cavity receiver is 5003 W, and the optical efficiency of this receiver is 70.8%. Numerical simulation is conducted to investigate the thermal performance of this modified receiver. The proposed receiver is also compared with other three simulated receivers combining the presence and absence of the quartz glass window and the secondary reflector. The numerical simulation results show that the modified receiver with both quartz glass window and secondary trumpet reflector outperformed other designs, and its heat loss is reduced about 56% compared to the initial receiver without both quartz glass window and secondary reflector. Hence, the impact factors on the modified receiver radiation and convection heat transfer are well analyzed including temperature, the inner surface orientation and emissivity. The research indicates that the proposed cavity receiver can efficiently reduce the heat loss from cavity and is suitable for Stirling engine applications.

  14. Effects of Cavity on the Performance of Dual Throat Nozzle During the Thrust-Vectoring Starting Transient Process.

    Science.gov (United States)

    Gu, Rui; Xu, Jinglei

    2014-01-01

    The dual throat nozzle (DTN) technique is capable to achieve higher thrust-vectoring efficiencies than other fluidic techniques, without compromising thrust efficiency significantly during vectoring operation. The excellent performance of the DTN is mainly due to the concaved cavity. In this paper, two DTNs of different scales have been investigated by unsteady numerical simulations to compare the parameter variations and study the effects of cavity during the vector starting process. The results remind us that during the vector starting process, dynamic loads may be generated, which is a potentially challenging problem for the aircraft trim and control.

  15. Proof-of-principle demonstration of Nb{sub 3}Sn superconducting radiofrequency cavities for high Q{sub 0} applications

    Energy Technology Data Exchange (ETDEWEB)

    Posen, S., E-mail: sep93@cornell.edu; Liepe, M.; Hall, D. L. [Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York 14853 (United States)

    2015-02-23

    Many future particle accelerators require hundreds of superconducting radiofrequency (SRF) cavities operating with high duty factor. The large dynamic heat load of the cavities causes the cryogenic plant to make up a significant part of the overall cost of the facility. This contribution can be reduced by replacing standard niobium cavities with ones coated with a low-dissipation superconductor such as Nb{sub 3}Sn. In this paper, we present results for single cell cavities coated with Nb{sub 3}Sn at Cornell. Five coatings were carried out, showing that at 4.2 K, high Q{sub 0} out to medium fields was reproducible, resulting in an average quench field of 14 MV/m and an average 4.2 K Q{sub 0} at quench of 8 × 10{sup 9}. In each case, the peak surface magnetic field at quench was well above H{sub c1}, showing that it is not a limiting field in these cavities. The coating with the best performance had a quench field of 17 MV/m, exceeding gradient requirements for state-of-the-art high duty factor SRF accelerators. It is also shown that—taking into account the thermodynamic efficiency of the cryogenic plant—the 4.2 K Q{sub 0} values obtained meet the AC power consumption requirements of state-of-the-art high duty factor accelerators, making this a proof-of-principle demonstration for Nb{sub 3}Sn cavities in future applications.

  16. Cavity-enhanced surface-plasmon resonance sensing: Modeling and performance

    Czech Academy of Sciences Publication Activity Database

    Giorgini, A.; Avino, S.; Malara, P.; Zullo, R.; Gaglio, G.; Homola, Jiří; De Natale, P.

    2014-01-01

    Roč. 25, č. 1 (2014), 015205 ISSN 0957-0233 Institutional support: RVO:67985882 Keywords : optical resonators * optical sensors * cavity ring-down spectroscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.433, year: 2014

  17. R high performance programming

    CERN Document Server

    Lim, Aloysius

    2015-01-01

    This book is for programmers and developers who want to improve the performance of their R programs by making them run faster with large data sets or who are trying to solve a pesky performance problem.

  18. Cavities at the Si projected range by high dose and energy Si ion implantation in Si

    International Nuclear Information System (INIS)

    Canino, M.; Regula, G.; Lancin, M.; Xu, M.; Pichaud, B.; Ntzoenzok, E.; Barthe, M.F.

    2009-01-01

    Two series of n-type Si samples α and β are implanted with Si ions at high dose (1 x 10 16 ) and high energies, 0.3 and 1.0 MeV, respectively. Both sort of samples are then implanted with 5 x 10 16 He cm -2 (at 10 or 50 keV) and eventually with B atoms. Some of the samples are annealed at temperatures ranging from 800 to 1000 deg. C to allow the thermal growth of He-cavities, located between sample surface and the projected range (R p ) of Si. After the triple ion implantation, which corresponds to defect engineering, samples were characterized by cross-section transmission electron microscopy (XTEM). Voids (or bubbles) are observed not only at the R p (He) on all annealed samples, but also at the R p (Si) on β samples implanted with He at 50 keV. The samples are also studied by positron annihilation spectroscopy (PAS) and the spectra confirm that as-implanted samples contain di-vacancies and that the annealed ones, even at high temperature have bigger open volumes, which are assumed to be the same voids observed by XTEM. It is demonstrated that a sole Si implantation at high energy and dose is efficient to create cavities which are thermally stable up to 1000 deg. C only in the presence of He.

  19. Quantum state engineering, purification, and number-resolved photon detection with high-finesse optical cavities

    DEFF Research Database (Denmark)

    Nielsen, Anne E. B.; Muschik, Christine A.; Giedke, Geza

    2010-01-01

    We propose and analyze a multifunctional setup consisting of high-finesse optical cavities, beam splitters, and phase shifters. The basic scheme projects arbitrary photonic two-mode input states onto the subspace spanned by the product of Fock states |n>|n> with n=0,1,2,.... This protocol does no...... is especially attractive as a generalization to many modes allows for distribution and purification of entanglement in networks. In an alternative working mode, the setup allows for quantum nondemolition number resolved photodetection in the optical domain....

  20. Plasmonic reflectors and high-Q nano-cavities based on coupled metal-insulator-metal waveguides

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2012-03-01

    Full Text Available Based on the contra-directional coupling, a composite structure consisting of two coupled metal-insulator-metal (MIM waveguides is proposed to act as an attractive plasmonic reflector. By introducing a defect into one of the MIM waveguides, we show that such a composite structure can be operated as a plasmonic nanocavity with a high quality factor. Both symmetric and anti-symmetric cavity modes are supported in the plasmonic cavity, and their resonance frequencies can be tuned by controlling the defect width. The present structures could have a significant impact for potential applications such as surface plasmon mirrors, filters and solid-state cavity quantum electrodynamics.

  1. CFD Model Development and validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications

    International Nuclear Information System (INIS)

    Hassan, Yassin; Corradini, Michael; Tokuhiro, Akira; Wei, Thomas Y.C.

    2014-01-01

    The Reactor Cavity Cooling Systems (RCCS) is a passive safety system that will be incorporated in the VTHR design. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady-state) and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The experimental data produced during the steady-state run were compared with the simulation results obtained using RELAP5-3D. The overall behavior of the facility met the expectations. The facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation.

  2. CFD Model Development and validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin [Univ. of Wisconsin, Madison, WI (United Texas A & M Univ., College Station, TX (United States); Corradini, Michael; Tokuhiro, Akira; Wei, Thomas Y.C.

    2014-07-14

    The Reactor Cavity Cooling Systems (RCCS) is a passive safety system that will be incorporated in the VTHR design. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady-state) and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The experimental data produced during the steady-state run were compared with the simulation results obtained using RELAP5-3D. The overall behavior of the facility met the expectations. The facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation.

  3. Tunable Resonant-Cavity-Enhanced Photodetector with Double High-Index-Contrast Grating Mirrors

    DEFF Research Database (Denmark)

    Learkthanakhachon, Supannee; Yvind, Kresten; Chung, Il-Sug

    2013-01-01

    In this paper, we propose a broadband-tunable resonant-cavity-enhanced photodetector (RCE-PD) structure with double high-index-contrast grating (HCG) mirrors and numerically investigate its characteristics. The detector is designed to operate at 1550-nm wavelength. The detector structure consists....... Furthermore, the fact that it can be fabricated on a silicon platform offers us a possibility of integration with electronics.......In this paper, we propose a broadband-tunable resonant-cavity-enhanced photodetector (RCE-PD) structure with double high-index-contrast grating (HCG) mirrors and numerically investigate its characteristics. The detector is designed to operate at 1550-nm wavelength. The detector structure consists...... of a top InP HCG mirror, a p-i-n photodiode embedding multiple quantum wells, and a Si HCG mirror formed in the Si layer of a silicon-on-insulator wafer. The detection wavelength can be changed by moving the top InP HCG mirror suspended in the air. High reflectivity and small penetration length of HCGs...

  4. Measurement of the high-field Q drop in the TM010 and TE011 modes in a niobium cavity

    Energy Technology Data Exchange (ETDEWEB)

    Gianluigi Ciovati; Peter Kneisel

    2006-04-01

    In the last few years superconducting radio-frequency (rf) cavities made of high-purity (residual resistivity ratio>200) niobium achieved accelerating gradients close to the theoretical limits. An obstacle towards achieving reproducibly higher fields is represented by ''anomalous'' losses causing a sharp degradation of the cavity quality factor when the peak surface magnetic field (Bp) is above about 90 mT, in the absence of field emission. This effect, called ''Q drop'' has been measured in many laboratories with single- and multicell cavities mainly in the gigahertz range. In addition, a low-temperature (100-140 C) ''in situ'' baking of the cavity was found to be beneficial in reducing the Q drop. In order to gain some understanding of the nature of these losses, a single-cell cavity has been tested in the TM010 and TE011 modes at 2 K. The feature of the TE011 mode is to have zero electric field on the cavity surface, so that electric field effects can be excluded as a source for the Q drop. This article will present some of the experimental results for different cavity treatments and will compare them with existing models.

  5. Measurement of the high-field Q drop in the TM_{010} and TE_{011} modes in a niobium cavity

    Directory of Open Access Journals (Sweden)

    Gianluigi Ciovati

    2006-04-01

    Full Text Available In the last few years superconducting radio-frequency (rf cavities made of high-purity (residual resistivity ratio>200 niobium achieved accelerating gradients close to the theoretical limits. An obstacle towards achieving reproducibly higher fields is represented by “anomalous” losses causing a sharp degradation of the cavity quality factor when the peak surface magnetic field (B_{p} is above about 90 mT, in the absence of field emission. This effect, called “Q drop” has been measured in many laboratories with single- and multicell cavities mainly in the gigahertz range. In addition, a low-temperature (100–140 °C “in situ” baking of the cavity was found to be beneficial in reducing the Q drop. In order to gain some understanding of the nature of these losses, a single-cell cavity has been tested in the TM_{010} and TE_{011} modes at 2 K. The feature of the TE_{011} mode is to have zero electric field on the cavity surface, so that electric field effects can be excluded as a source for the Q drop. This article will present some of the experimental results for different cavity treatments and will compare them with existing models.

  6. High performance work practices, innovation and performance

    DEFF Research Database (Denmark)

    Jørgensen, Frances; Newton, Cameron; Johnston, Kim

    2013-01-01

    Research spanning nearly 20 years has provided considerable empirical evidence for relationships between High Performance Work Practices (HPWPs) and various measures of performance including increased productivity, improved customer service, and reduced turnover. What stands out from......, and Africa to examine these various questions relating to the HPWP-innovation-performance relationship. Each paper discusses a practice that has been identified in HPWP literature and potential variables that can facilitate or hinder the effects of these practices of innovation- and performance...

  7. Design of 325 MHz spoke cavity

    International Nuclear Information System (INIS)

    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)

  8. Role of cavity formation in SCC of cold worked carbon steel in high-temperature water. Part 2. Study of crack initiation behavior

    International Nuclear Information System (INIS)

    Yamada, Takuyo; Aoki, Masanori; Miyamoto, Tomoki; Arioka, Koji

    2013-01-01

    To consider the role of cavity formation in stress corrosion cracking (SCC) of cold worked (CW) carbon steel in high-temperature water, SCC and creep growth (part 1) and initiation (part 2) tests were performed. The part 2 crack initiation tests used blunt notched compact tension (CT) type specimens of CW carbon steel exposed under the static load condition in hydrogenated pure water and in air in the range of temperatures between 360 and 450°C. Inter-granular (IG) crack initiation was observed both in water and in air even in static load condition when steel specimens had been cold worked. 1/T type temperature dependencies of initiation times were observed for CW carbon steel, and the crack initiation times in an operating pressurized heavy water reactor, PHWR (Pt Lepreau) seemed to lie on the extrapolated line of the experimental results. Cavities were identified at the grain boundaries near the bottom of a notch (highly stressed location) before cracks initiated both in water and air. The cavities were probably formed by the condensation of vacancies and they affected the bond strength of the grain boundaries. To assess the mechanism of IGSCC initiation in high temperature water, the diffusion of vacancies driven by stress gradients was studied using a specially designed CT specimen. As a model for IGSCC in CW carbon steel in high temperature water, it was concluded that the formation of cavities from the collapse of vacancies offers the best interpretation of the present data. (author)

  9. Additive Manufactured Superconducting Cavities

    Science.gov (United States)

    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.

  10. External-cavity high-power dual-wavelength tapered amplifier with tunable THz frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2012-01-01

    A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W is achie......A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W...... is achieved with a frequency difference of 0.86 THz, the output power is higher than 1.3 W in the 5.0 THz range of frequency difference, and the amplified spontaneous emission intensity is more than 20 dB suppressed in the range of frequency difference. The beam quality factor M2 is 1.22±0.15 at an output...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Synergies Between ' and Cavity Formation in HT-9 Following High Dose Neutron Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parish, Chad M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Saleh, Tarik A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eftink, Benjamin P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-01

    Candidate cladding materials for advanced nuclear power reactors including fast reactor designs require materials capable of withstanding high dose neutron irradiation at elevated temperatures. One candidate material, HT-9, through various research programs have demonstrated the ability to withstand significant swelling and other radiation-induced degradation mechanisms in the high dose regime (>50 displacements per atom, dpa) at elevated temperatures (>300 C). Here, high efficiency multi-dimensional scanning transmission electron microscopy (STEM) acquisition with the aid of a three-dimensional (3D) reconstruction and modeling technique is used to probe the microstructural features that contribute to the exceptional swelling resistance of HT-9. In particular, the synergies between ' and fine-scale and moderate-scale cavity formation is investigated.

  13. Highly uniform residual layers for arrays of 3D nanoimprinted cavities in Fabry-Pérot-filter-array-based nanospectrometers

    Science.gov (United States)

    Memon, Imran; Shen, Yannan; Khan, Abdullah; Woidt, Carsten; Hillmer, Hartmut

    2016-04-01

    Miniaturized optical spectrometers can be implemented by an array of Fabry-Pérot (FP) filters. FP filters are composed of two highly reflecting parallel mirrors and a resonance cavity. Each filter transmits a small spectral band (filter line) depending on its individual cavity height. The optical nanospectrometer, a miniaturized FP-based spectrometer, implements 3D NanoImprint technology for the fabrication of multiple FP filter cavities in a single process step. However, it is challenging to avoid the dependency of residual layer (RL) thickness on the shape of the printed patterns in NanoImprint. Since in a nanospectrometer the filter cavities vary in height between neighboring FP filters and, thus, the volume of each cavity varies causing that the RL varies slightly or noticeably between different filters. This is one of the few disadvantages of NanoImprint using soft templates such as substrate conformal imprint lithography which is used in this paper. The advantages of large area soft templates can be revealed substantially if the problem of laterally inhomogeneous RLs can be avoided or reduced considerably. In the case of the nanospectrometer, non-uniform RLs lead to random variations in the designed cavity heights resulting in the shift of desired filter lines. To achieve highly uniform RLs, we report a volume-equalized template design with the lateral distribution of 64 different cavity heights into several units with each unit comprising four cavity heights. The average volume of each unit is kept constant to obtain uniform filling of imprint material per unit area. The imprint results, based on the volume-equalized template, demonstrate highly uniform RLs of 110 nm thickness.

  14. Parallel Adjective High-Order CFD Simulations Characterizing SOFIA Cavity Acoustics

    Science.gov (United States)

    Barad, Michael F.; Brehm, Christoph; Kiris, Cetin C.; Biswas, Rupak

    2016-01-01

    This paper presents large-scale MPI-parallel computational uid dynamics simulations for the Stratospheric Observatory for Infrared Astronomy (SOFIA). SOFIA is an airborne, 2.5-meter infrared telescope mounted in an open cavity in the aft fuselage of a Boeing 747SP. These simulations focus on how the unsteady ow eld inside and over the cavity interferes with the optical path and mounting structure of the telescope. A temporally fourth-order accurate Runge-Kutta, and spatially fth-order accurate WENO- 5Z scheme was used to perform implicit large eddy simulations. An immersed boundary method provides automated gridding for complex geometries and natural coupling to a block-structured Cartesian adaptive mesh re nement framework. Strong scaling studies using NASA's Pleiades supercomputer with up to 32k CPU cores and 4 billion compu- tational cells shows excellent scaling. Dynamic load balancing based on execution time on individual AMR blocks addresses irregular numerical cost associated with blocks con- taining boundaries. Limits to scaling beyond 32k cores are identi ed, and targeted code optimizations are discussed.

  15. Python high performance programming

    CERN Document Server

    Lanaro, Gabriele

    2013-01-01

    An exciting, easy-to-follow guide illustrating the techniques to boost the performance of Python code, and their applications with plenty of hands-on examples.If you are a programmer who likes the power and simplicity of Python and would like to use this language for performance-critical applications, this book is ideal for you. All that is required is a basic knowledge of the Python programming language. The book will cover basic and advanced topics so will be great for you whether you are a new or a seasoned Python developer.

  16. High performance germanium MOSFETs

    Energy Technology Data Exchange (ETDEWEB)

    Saraswat, Krishna [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)]. E-mail: saraswat@stanford.edu; Chui, Chi On [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Krishnamohan, Tejas [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Kim, Donghyun [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Nayfeh, Ammar [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States); Pethe, Abhijit [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

    2006-12-15

    Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO {sub x}N {sub y} ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15 nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin ({approx}2 nm) strained-Ge channel heterostructure MOSFETs exhibited >4x mobility enhancements over bulk Si devices and >10x BTBT reduction over surface channel strained SiGe devices.

  17. High performance germanium MOSFETs

    International Nuclear Information System (INIS)

    Saraswat, Krishna; Chui, Chi On; Krishnamohan, Tejas; Kim, Donghyun; Nayfeh, Ammar; Pethe, Abhijit

    2006-01-01

    Ge is a very promising material as future channel materials for nanoscale MOSFETs due to its high mobility and thus a higher source injection velocity, which translates into higher drive current and smaller gate delay. However, for Ge to become main-stream, surface passivation and heterogeneous integration of crystalline Ge layers on Si must be achieved. We have demonstrated growth of fully relaxed smooth single crystal Ge layers on Si using a novel multi-step growth and hydrogen anneal process without any graded buffer SiGe layer. Surface passivation of Ge has been achieved with its native oxynitride (GeO x N y ) and high-permittivity (high-k) metal oxides of Al, Zr and Hf. High mobility MOSFETs have been demonstrated in bulk Ge with high-k gate dielectrics and metal gates. However, due to their smaller bandgap and higher dielectric constant, most high mobility materials suffer from large band-to-band tunneling (BTBT) leakage currents and worse short channel effects. We present novel, Si and Ge based heterostructure MOSFETs, which can significantly reduce the BTBT leakage currents while retaining high channel mobility, making them suitable for scaling into the sub-15 nm regime. Through full band Monte-Carlo, Poisson-Schrodinger and detailed BTBT simulations we show a dramatic reduction in BTBT and excellent electrostatic control of the channel, while maintaining very high drive currents in these highly scaled heterostructure DGFETs. Heterostructure MOSFETs with varying strained-Ge or SiGe thickness, Si cap thickness and Ge percentage were fabricated on bulk Si and SOI substrates. The ultra-thin (∼2 nm) strained-Ge channel heterostructure MOSFETs exhibited >4x mobility enhancements over bulk Si devices and >10x BTBT reduction over surface channel strained SiGe devices

  18. High density of tree-cavities and snags in tropical dry forest of western Mexico raises questions for a latitudinal gradient.

    Directory of Open Access Journals (Sweden)

    Leopoldo Vázquez

    Full Text Available It has been suggested that a latitudinal gradient exists of a low density of snags and high density of naturally-formed tree-cavities in tropical vs. temperate forests, though few cavities may have characteristics suitable for nesting by birds. We determined snag and cavity density, characteristics, and suitability for birds in a tropical dry forest biome of western Mexico, and evaluated whether our data fits the trend of snag and cavity density typically found in tropical moist and wet forests. We established five 0.25-ha transects to survey and measure tree-cavities and snags in each of three vegetation types of deciduous, semi-deciduous, and mono-dominant Piranhea mexicana forest, comprising a total of 3.75 ha. We found a high density of 77 cavities/ha, with 37 cavities suitable for birds/ha, where density, and characteristics of cavities varied significantly among vegetation types. Lowest abundance of cavities occurred in deciduous forest, and these were in smaller trees, at a lower height, and with a narrower entrance diameter. Only 8.6% of cavities were excavated by woodpeckers, and only 11% of cavities were occupied, mainly by arthropods, though 52% of all cavities were unsuitable for birds. We also found a high density of 56 snags/ha, with greatest density in deciduous forest (70 snags/ha, though these were of significantly smaller diameter, and snags of larger diameter were more likely to contain cavities. The Chamela-Cuixmala tropical dry forest had the highest density of snags recorded for any tropical or temperate forest, and while snag density was significantly correlated with mean snag dbh, neither latitude nor mean dbh predicted snag density in ten forest sites. The high spatial aggregation of snag and cavity resources in tropical dry forest may limit their availability, particularly for large-bodied cavity adopters, and highlights the importance of habitat heterogeneity in providing resources for primary and secondary cavity-nesters.

  19. High density of tree-cavities and snags in tropical dry forest of western Mexico raises questions for a latitudinal gradient.

    Science.gov (United States)

    Vázquez, Leopoldo; Renton, Katherine

    2015-01-01

    It has been suggested that a latitudinal gradient exists of a low density of snags and high density of naturally-formed tree-cavities in tropical vs. temperate forests, though few cavities may have characteristics suitable for nesting by birds. We determined snag and cavity density, characteristics, and suitability for birds in a tropical dry forest biome of western Mexico, and evaluated whether our data fits the trend of snag and cavity density typically found in tropical moist and wet forests. We established five 0.25-ha transects to survey and measure tree-cavities and snags in each of three vegetation types of deciduous, semi-deciduous, and mono-dominant Piranhea mexicana forest, comprising a total of 3.75 ha. We found a high density of 77 cavities/ha, with 37 cavities suitable for birds/ha, where density, and characteristics of cavities varied significantly among vegetation types. Lowest abundance of cavities occurred in deciduous forest, and these were in smaller trees, at a lower height, and with a narrower entrance diameter. Only 8.6% of cavities were excavated by woodpeckers, and only 11% of cavities were occupied, mainly by arthropods, though 52% of all cavities were unsuitable for birds. We also found a high density of 56 snags/ha, with greatest density in deciduous forest (70 snags/ha), though these were of significantly smaller diameter, and snags of larger diameter were more likely to contain cavities. The Chamela-Cuixmala tropical dry forest had the highest density of snags recorded for any tropical or temperate forest, and while snag density was significantly correlated with mean snag dbh, neither latitude nor mean dbh predicted snag density in ten forest sites. The high spatial aggregation of snag and cavity resources in tropical dry forest may limit their availability, particularly for large-bodied cavity adopters, and highlights the importance of habitat heterogeneity in providing resources for primary and secondary cavity-nesters.

  20. High Performance Computing Multicast

    Science.gov (United States)

    2012-02-01

    A History of the Virtual Synchrony Replication Model,” in Replication: Theory and Practice, Charron-Bost, B., Pedone, F., and Schiper, A. (Eds...Performance Computing IP / IPv4 Internet Protocol (version 4.0) IPMC Internet Protocol MultiCast LAN Local Area Network MCMD Dr. Multicast MPI

  1. NGINX high performance

    CERN Document Server

    Sharma, Rahul

    2015-01-01

    System administrators, developers, and engineers looking for ways to achieve maximum performance from NGINX will find this book beneficial. If you are looking for solutions such as how to handle more users from the same system or load your website pages faster, then this is the book for you.

  2. NUMERICAL SIMULATIONS OF FLOW BEHAVIOR IN DRIVEN CAVITY AT HIGH REYNOLDS NUMBERS

    Directory of Open Access Journals (Sweden)

    Fudhail Bin Abdul Munir

    2012-02-01

    Full Text Available In recent years, due to rapidly increasing computational power, computational methods have become the essential tools to conduct researches in various engineering fields.  In parallel to the development of ultra high speed digital computers, computational fluid dynamics (CFD has become the new third approach apart from theory and experiment in the philosophical study and development of fluid dynamics.  Lattice Boltzmann method (LBM is an alternative method to conventional CFD.  LBM is relatively new approach that uses simple microscopic models to simulate complicated microscopic behavior of transport phenomena.  In this paper, fluid flow behaviors of steady incompressible flow inside lid driven square cavity are studied.  Numerical calculations are conducted for different Reynolds numbers by using Lattice Boltzmann scheme.  The objective of the paper is to demonstrate the capability of this lattice Boltzmann scheme for engineering applications particularly in fluid transport phenomena. Keywords-component; lattice Boltzmann method, lid driven cavity, computational fluid dynamics.

  3. High-Q submicron-diameter quantum-dot microcavity pillars for cavity QED experiments

    DEFF Research Database (Denmark)

    Gregersen, Niels; Lermer, Matthias; Dunzer, Florian

    As/AlAs micropillar design where Bloch-wave engineering is employed to significally enhance the cavity mode confinement in the submicron diameter regime. We demonstrate a record-high vacuum Rabi splitting of 85 µeV of the strong coupling for pillars incorporating quantum dots with modest oscillator strength f ≈ 10....... It is well-known that light-matter interaction depends on the photonic environment, and thus proper engineering of the optical mode in microcavity systems is central to obtaining the desired functionality. In the strong coupling regime, the visibility of the Rabi splitting is described by the light...... coupling in micropillars relied on quantum dots with high oscillator strengths f > 50, our advanced design allows for the observation of strong coupling for submicron diameter quantum dot-pillars with standard f ≈ 10 oscillator strength. A quality factor of 13600 and a vacuum Rabi splitting of 85 µe...

  4. Cavity resonance absorption in ultra-high bandwidth CRT deflection structure by a resistive load

    Science.gov (United States)

    Dunham, M.E.; Hudson, C.L.

    1993-05-11

    An improved ultra-high bandwidth helical coil deflection structure for a cathode ray tube is described comprising a first metal member having a bore therein, the metal walls of which form a first ground plane; a second metal member coaxially mounted in the bore of the first metal member and forming a second ground plane; a helical deflection coil coaxially mounted within the bore between the two ground planes; and a resistive load disposed in one end of the bore and electrically connected to the first and second ground planes, the resistive load having an impedance substantially equal to the characteristic impedance of the coaxial line formed by the two coaxial ground planes to inhibit cavity resonance in the structure within the ultra-high bandwidth of operation. Preferably, the resistive load comprises a carbon film on a surface of an end plug in one end of the bore.

  5. Study of a spoke-type superconducting cavity for high power proton accelerators; Etude d'une cavite acceleratrice supraconductrice Spoke pour les accelerateurs de protons de forte intensite

    Energy Technology Data Exchange (ETDEWEB)

    Olry, G

    2003-04-01

    Since a few years, a lot of projects (especially dedicated to transmutation, radioactive beams production, spallation neutron sources or neutrinos factories) are based on high power proton linear accelerators. It has been demonstrated, thanks to their excellent RF performances, that superconducting elliptical cavities represent the best technological solution for the high energy part of these linacs (proton energy from typically 100 MeV). On the contrary, between 5 and 100 MeV, nothing is clearly settled and intensive studies on low-beta cavities are under progress. The main objective of this thesis is the study of a new low-beta cavity, called 'spoke', which could be used in the low energy part of European XADS (experimental accelerator driven system) and EURISOL (European isotope separation on-line) accelerators projects. A complete study of a beta 0.35 spoke cavity has been done: from its electromagnetic and mechanical optimization to warm and, above all, cold experimental tests: an accelerating field of 12.2 MV/m has been reached at T=4.2 K, that is to say one of the best value among the spoke cavities performances in the world. It has been shown that the specific ratio of a third, between the spoke bar diameter and the cavity length, led to optimize the surface electromagnetic fields. Moreover, spoke cavities can be used without any trouble, in the low energy part, due to their good rigidity. The experimental measurements performed on the cavity have confirmed the theoretical calculations, especially, concerning the expected frequency and mechanical behavior. Another study, performed on elliptical cavities, gave an explanation of the discrepancies between the measured and calculated frequencies thanks to a precise 3-dimensional geometrical control. (author)

  6. Performance of a light applicator for photodynamic therapy in the oral cavity: calculations and measurements

    NARCIS (Netherlands)

    van Benthem, H. E.; Sterenborg, H. J.; van der Meulen, F. W.; van Gemert, M. J.

    1997-01-01

    Photodynamic therapy (PDT) is an experimental therapy for the treatment of superficial cancer using laser light. In PDT a uniform light distribution is usually required for an optimal therapeutic effect. To irradiate part of the oral cavity uniformly for PDT, two prototype applicators were built,

  7. High Pressure Gas Filled RF Cavity Beam Test at the Fermilab MuCool Test Area

    Energy Technology Data Exchange (ETDEWEB)

    Freemire, Ben [Illinois Inst. of Technology, Chicago, IL (United States)

    2013-05-01

    The high energy physics community is continually looking to push the limits with respect to the energy and luminosity of particle accelerators. In the realm of leptons, only electron colliders have been built to date. Compared to hadrons, electrons lose a large amount of energy when accelerated in a ring through synchrotron radiation. A solution to this problem is to build long, straight accelerators for electrons, which has been done with great success. With a new generation of lepton colliders being conceived, building longer, more powerful accelerators is not the most enticing option. Muons have been proposed as an alternative particle to electrons. Muons lose less energy to synchrotron radiation and a Muon Collider can provide luminosity within a much smaller energy range than a comparable electron collider. This allows a circular collider to be built with higher attainable energy than any present electron collider. As part of the accelerator, but separate from the collider, it would also be possible to allow the muons to decay to study neutrinos. The possibility of a high energy, high luminosity muon collider and an abundant, precise source of neutrinos is an attractive one. The technological challenges of building a muon accelerator are many and diverse. Because the muon is an unstable particle, a muon beam must be cooled and accelerated to the desired energy within a short amount of time. This requirement places strict requisites on the type of acceleration and focusing that can be used. Muons are generated as tertiary beams with a huge phase space, so strong magnetic fields are required to capture and focus them. Radio frequency (RF) cavities are needed to capture, bunch and accelerate the muons. Unfortunately, traditional vacuum RF cavities have been shown to break down in the magnetic fields necessary for capture and focusing.

  8. Calibrated high-precision 17O-excess measurements using cavity ring-down spectroscopy with laser-current-tuned cavity resonance

    Directory of Open Access Journals (Sweden)

    E. J. Steig

    2014-08-01

    Full Text Available High-precision analysis of the 17O / 16O isotope ratio in water and water vapor is of interest in hydrological, paleoclimate, and atmospheric science applications. Of specific interest is the parameter 17O excess (Δ17O, a measure of the deviation from a~linear relationship between 17O / 16O and 18O / 16O ratios. Conventional analyses of Δ17O of water are obtained by fluorination of H2O to O2 that is analyzed by dual-inlet isotope ratio mass spectrometry (IRMS. We describe a new laser spectroscopy instrument for high-precision Δ17O measurements. The new instrument uses cavity ring-down spectroscopy (CRDS with laser-current-tuned cavity resonance to achieve reduced measurement drift compared with previous-generation instruments. Liquid water and water-vapor samples can be analyzed with a better than 8 per meg precision for Δ17O using integration times of less than 30 min. Calibration with respect to accepted water standards demonstrates that both the precision and the accuracy of Δ17O are competitive with conventional IRMS methods. The new instrument also achieves simultaneous analysis of δ18O, Δ17O and δD with precision of < 0.03‰, < 0.02 and < 0.2‰, respectively, based on repeated calibrated measurements.

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

    Science.gov (United States)

    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.

  10. Prediction and experimental verification of performance of box type solar cooker - Part I. Cooking vessel with central cylindrical cavity

    International Nuclear Information System (INIS)

    Reddy, Avala Raji; Rao, A.V. Narasimha

    2007-01-01

    The performance of conventional box type solar cookers can be improved by better designs of cooking vessels with proper understanding of the heat flow to the material to be cooked. An attempt has been made in this article to arrive at a mathematical model to understand the heat flow process to the cooking vessel and thereby to the food material. The mathematical model considers a double glazed hot box type solar cooker loaded with two different types of vessels, kept either on the floor of the cooker or on lugs. The performance of the cooking vessel with a central cylindrical cavity is compared with that of a conventional cylindrical cooking vessel. It is found from the experiments and modeling that the cooking vessel with a central cylindrical cavity on lugs results in a higher temperature of the thermic fluid than that of a conventional vessel on the floor or on lugs. The average improvement of performance of the vessel with a central cylindrical cavity kept on lugs is found to be 5.9% and 2.4% more than that of a conventional cylindrical vessel on the floor and on lugs, respectively

  11. High performance proton accelerators

    International Nuclear Information System (INIS)

    Favale, A.J.

    1989-01-01

    In concert with this theme this paper briefly outlines how Grumman, over the past 4 years, has evolved from a company that designed and fabricated a Radio Frequency Quadrupole (RFQ) accelerator from the Los Alamos National Laboratory (LANL) physics and specifications to a company who, as prime contractor, is designing, fabricating, assembling and commissioning the US Army Strategic Defense Commands (USA SDC) Continuous Wave Deuterium Demonstrator (CWDD) accelerator as a turn-key operation. In the case of the RFQ, LANL scientists performed the physics analysis, established the specifications supported Grumman on the mechanical design, conducted the RFQ tuning and tested the RFQ at their laboratory. For the CWDD Program Grumman has the responsibility for the physics and engineering designs, assembly, testing and commissioning albeit with the support of consultants from LANL, Lawrence Berkeley Laboratory (LBL) and Brookhaven National laboratory. In addition, Culham Laboratory and LANL are team members on CWDD. LANL scientists have reviewed the physics design as well as a USA SDC review board. 9 figs

  12. High-power, solid-state rf source for accelerator cavities

    International Nuclear Information System (INIS)

    Vaughan, D.R.; Mols, G.E.; Reid, D.W.; Potter, J.M.

    1985-01-01

    During the past few years the Defense and Electronics Center of Westinghouse Electric Corporation has developed a solid-state, 250-kW peak, rf amplifier for use with the SPS-40 radar system. This system has a pulse length of 60 μs and operates across the frequency band from 400 to 450 MHz. Because of the potential use of such a system as an rf source for accelerator applications, a collaborative experiment was initiated between Los Alamos National Laboratory and Westinghouse to simulate the resonant load conditions of an accelerator cavity. This paper describes the positive results of that experiment as well as the solid-state amplifier architecture. It also explores the future of high-power, solid-state amplifiers as rf sources for accelerator structures

  13. A metrology system for a high resolution cavity beam position monitor system

    Energy Technology Data Exchange (ETDEWEB)

    Walston, Sean, E-mail: walston2@llnl.gov [Lawrence Livermore National Laboratory, 7000 East Ave., L-181, Livermore, CA 94550 (United States); Boogert, Stewart [Royal Holloway, University of London, Egham (United Kingdom); Chung, Carl; Fitsos, Pete [Lawrence Livermore National Laboratory, 7000 East Ave., L-181, Livermore, CA 94550 (United States); Frisch, Joe [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Gronberg, Jeff [Lawrence Livermore National Laboratory, 7000 East Ave., L-181, Livermore, CA 94550 (United States); Hayano, Hitoshi [High Energy Accelerator Research Organization (KEK), Tsukuba-shi, Ibaraki-ken (Japan); Hinton, Shantell [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Honda, Yosuke [High Energy Accelerator Research Organization (KEK), Tsukuba-shi, Ibaraki-ken (Japan); Khainovski, Oleg; Kolomensky, Yury; Loscutoff, Peter [University of California and Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Lyapin, Alexey; Malton, Stephen [University College London, London (United Kingdom); May, Justin; McCormick, Douglas [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Meller, Robert [Cornell University, Ithaca, NY (United States); Miller, David [University College London, London (United Kingdom); Orimoto, Toyoko [University of California and Lawrence Berkeley National Laboratory, Berkeley, CA (United States); California Institute of Technology, Pasadena, CA (United States); Ross, Marc [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Fermi National Accelerator Laboratory, Batavia, IL (United States); and others

    2013-11-11

    International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will likely be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved–ideally using a beam-based stability measurement. We developed a high resolution RF cavity Beam Position Monitor (BPM) system. A triplet of these BPMs, installed in the extraction line of the KEK Accelerator Test Facility (ATF) and tested with its ultra-low emittance beam, achieved a position measurement resolution of 15 nm. A metrology system for the three BPMs was subsequently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame. We have demonstrated that the three BPMs behave as a rigid-body at the level of less than 5 nm.

  14. Simulations of fast crab cavity failures in the high luminosity Large Hadron Collider

    Science.gov (United States)

    Yee-Rendon, Bruce; Lopez-Fernandez, Ricardo; Barranco, Javier; Calaga, Rama; Marsili, Aurelien; Tomás, Rogelio; Zimmermann, Frank; Bouly, Frédéric

    2014-05-01

    Crab cavities (CCs) are a key ingredient of the high luminosity Large Hadron Collider (HL-LHC) project for increasing the luminosity of the LHC. At KEKB, CCs have exhibited abrupt changes of phase and voltage during a time period of the order of a few LHC turns and considering the significant stored energy in the HL-LHC beam, CC failures represent a serious threat in regard to LHC machine protection. In this paper, we discuss the effect of CC voltage or phase changes on a time interval similar to, or longer than, the one needed to dump the beam. The simulations assume a quasistationary-state distribution to assess the particles losses for the HL-LHC. These distributions produce beam losses below the safe operation threshold for Gaussian tails, while, for non-Gaussian tails are on the same order of the limit. Additionally, some mitigation strategies are studied for reducing the damage caused by the CC failures.

  15. A metrology system for a high resolution cavity beam position monitor system

    Science.gov (United States)

    Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Pete; Frisch, Joe; Gronberg, Jeff; Hayano, Hitoshi; Hinton, Shantell; Honda, Yosuke; Khainovski, Oleg; Kolomensky, Yury; Loscutoff, Peter; Lyapin, Alexey; Malton, Stephen; May, Justin; McCormick, Douglas; Meller, Robert; Miller, David; Orimoto, Toyoko; Ross, Marc; Slater, Mark; Smith, Steve; Smith, Tonee; Terunuma, Nobuhiro; Thomson, Mark; Urakawa, Junji; Vogel, Vladimir; Ward, David; White, Glen

    2013-11-01

    International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will likely be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved-ideally using a beam-based stability measurement. We developed a high resolution RF cavity Beam Position Monitor (BPM) system. A triplet of these BPMs, installed in the extraction line of the KEK Accelerator Test Facility (ATF) and tested with its ultra-low emittance beam, achieved a position measurement resolution of 15 nm. A metrology system for the three BPMs was subsequently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame. We have demonstrated that the three BPMs behave as a rigid-body at the level of less than 5 nm.

  16. A global, high-resolution data set of ice sheet topography, cavity geometry, and ocean bathymetry

    Science.gov (United States)

    Schaffer, Janin; Timmermann, Ralph; Arndt, Jan Erik; Savstrup Kristensen, Steen; Mayer, Christoph; Morlighem, Mathieu; Steinhage, Daniel

    2016-10-01

    The ocean plays an important role in modulating the mass balance of the polar ice sheets by interacting with the ice shelves in Antarctica and with the marine-terminating outlet glaciers in Greenland. Given that the flux of warm water onto the continental shelf and into the sub-ice cavities is steered by complex bathymetry, a detailed topography data set is an essential ingredient for models that address ice-ocean interaction. We followed the spirit of the global RTopo-1 data set and compiled consistent maps of global ocean bathymetry, upper and lower ice surface topographies, and global surface height on a spherical grid with now 30 arcsec grid spacing. For this new data set, called RTopo-2, we used the General Bathymetric Chart of the Oceans (GEBCO_2014) as the backbone and added the International Bathymetric Chart of the Arctic Ocean version 3 (IBCAOv3) and the International Bathymetric Chart of the Southern Ocean (IBCSO) version 1. While RTopo-1 primarily aimed at a good and consistent representation of the Antarctic ice sheet, ice shelves, and sub-ice cavities, RTopo-2 now also contains ice topographies of the Greenland ice sheet and outlet glaciers. In particular, we aimed at a good representation of the fjord and shelf bathymetry surrounding the Greenland continent. We modified data from earlier gridded products in the areas of Petermann Glacier, Hagen Bræ, and Sermilik Fjord, assuming that sub-ice and fjord bathymetries roughly follow plausible Last Glacial Maximum ice flow patterns. For the continental shelf off Northeast Greenland and the floating ice tongue of Nioghalvfjerdsfjorden Glacier at about 79° N, we incorporated a high-resolution digital bathymetry model considering original multibeam survey data for the region. Radar data for surface topographies of the floating ice tongues of Nioghalvfjerdsfjorden Glacier and Zachariæ Isstrøm have been obtained from the data centres of Technical University of Denmark (DTU), Operation Icebridge (NASA

  17. Niobium LEP 2 accelerating cavities

    CERN Multimedia

    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.

  18. Tunable high-power narrow-spectrum external-cavity diode laser based on tapered amplifier at 668 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Erbert, G.; Sumpf, B.

    2010-01-01

    A 668 nm tunable high-power narrow-spectrum diode laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The laser system is tunable from 659 to 675 nm. As high as 1.38 W output power is obtained at 668.35 nm. The emission spectral bandwidth is less than...

  19. Effect of Curved Radial Vane Cavity Arrangements on Predicted Inter-Turbine Burner (ITB) Performance

    Science.gov (United States)

    2007-06-01

    in the cavity, and the vaporization, mixing of fuel and air, and combustion amount of unburned fuel shedding out of the becomes very challenging ...the payoff UUC/ITB concepts becomes critical. UCC/ITB was provided to define the geometry and served flamy hco de wih a ane as the staring point for...for the development and equations for mass, momentum, energy, chemical species, modification of the computer- aided design models, as and turbulence were

  20. Continued conditioning of the Fermilab 400 MeV linac high-gradient side-coupled cavities

    International Nuclear Information System (INIS)

    Kroc, Thomas; McCrory, Elliott; Moretti, Alfred; Popovic, Milorad

    1996-01-01

    The high-energy portion of the Fermilab 400 MeV Linac is made of high gradient (37 MV/meter surface field) side-coupled cavity sections which were conditioned over a 10 month period before their installation in August of 1993. We have continued to monitor the conditioning of these cavities since that time while the cavities have been in operation, and those results are presented here. The sparking rate and the X-ray production are measured and compared with the 1992/3 pre-operational and 1993/4 early operational measurements. These rates are consistent with a continued diminishing of these phenomena. Predictions and spark management strategies presented in earlier reports are evaluated in light of present experiences. We also have been measuring the sparking rate within this structure with and without our 50 mA peak beam. We find that the sparking rate is 20% higher with beam in the accelerator. (author)

  1. Study of a high finesse four mirrors Fabry Perot cavity for X-rays and Gamma rays production by laser-electron Compton scattering

    International Nuclear Information System (INIS)

    Fedala, Y.

    2008-10-01

    The main goal of this thesis is the study and design of a high finesse Fabry Perot cavity to amplify a laser beam in order to achieve power gains ranging from 10 4 to 10 5 . This cavity is dedicated to the production of intense and monochromatic X-ray for medical applications (medical RADIOTHOMX ring) and gamma rays for a Compton based polarized positron source by Compton scattering of a high power laser beam and electron beam. To increase the brightness of the Compton interaction at the collision points, it is essential to have not only a high power laser beam but also very small laser beam radii at the interaction points. To achieve such performances, 2 scenarios are possible: a concentric 2 mirrors cavity which is mechanically unstable or a 4 mirrors cavity more complex but more stable. We tested numerically mechanical stability and stability of Eigen modes polarization of various planar and non-planar geometries of 4 mirrors cavities. Experimentally, we have developed a four mirrors tetrahedral 'bow-tie' cavity; radii of the order of 20 microns were made. The Eigen modes of such a cavity, in both planar and non planar geometries, were measured and compared with the numerical results. A good agreement was observed. In a second time, the impact of Compton interaction on the transverse dynamics, in the case of the polarized positrons source, and the longitudinal dynamic, in the case of the medical ring of the electron beam was studied. Compton scattering causes energy loss and induces an additional dispersion of energy in electron beam. For the polarized positrons source, 10 collision points are planned. The transport line has been determined and the modelling of the Compton interaction effect with a simple matrix calculation was made. For the medical ring, Compton scattering causes bunch lengthening and the increase of energy dispersion which are to influence the produced X-ray flux. A study of the longitudinal dynamics of the electron beam in the ring was

  2. Theoretical investigation of anomalously high efficiency in a three cavity gyroklystron amplifier

    International Nuclear Information System (INIS)

    Latham, P.E.; Koc, U.V.; Main, W.; Tantawi, S.G.

    1992-01-01

    The University of Maryland's three cavity gyroklystron amplifier operating at a frequency of 10 GHz, voltage of 425 kV, current of 160 A, and pitch angle (v perpendicular/v z ) near .82, has demonstrated an efficiency of 35%. The author's simulations using fixed field profiles predict a significantly lower efficiency, primarily because of the small pitch angle in the experiment. They will be investigating two methods of improving the efficiency in their simulations: Beam-wave interaction after the output cavity, and modification of the first two cavity Qs due to beam loading. Results of their nonlinear code will be given for both cases

  3. A high-resolution EPR-CT microscope using cavity-resonators equipped with small field gradient coils

    International Nuclear Information System (INIS)

    Miki, T.; Murata, T.; Kumai, H.; Yamashiro, A.

    1996-01-01

    Cylindrical cavity resonators equipped with field gradient coils were developed for two-dimensional EPR-CT microscope systems. The field gradient coils lie in four (or six) thin metal tubes placed along the direction of the microwave magnetic field in the cavity to minimize impact on the resonator's quality factor. Two pairs of the tubes carry a 100 kHz current for magnetic field modulation. This cavity has high spin-detection sensitivity and can provide EPR images with submillimeter resolution. In order to reconstruct better images from fewer projections, we used an algebraic reconstruction technique (ART) for the two-dimensional image reconstruction. The ART method may be suitable for not only spectral-spatial two-dimensional EPR imaging, but also spatio-temporal EPR imaging in dynamic spin systems. (author)

  4. Nanoscale resonant-cavity-enhanced germanium photodetectors with lithographically defined spectral response for improved performance at telecommunications wavelengths.

    Science.gov (United States)

    Balram, Krishna C; Audet, Ross M; Miller, David A B

    2013-04-22

    We demonstrate the use of a subwavelength planar metal-dielectric resonant cavity to enhance the absorption of germanium photodetectors at wavelengths beyond the material's direct absorption edge, enabling high responsivity across the entire telecommunications C and L bands. The resonant wavelength of the detectors can be tuned linearly by varying the width of the Ge fin, allowing multiple detectors, each resonant at a different wavelength, to be fabricated in a single-step process. This approach is promising for the development of CMOS-compatible devices suitable for integrated, high-speed, and energy-efficient photodetection at telecommunications wavelengths.

  5. RF properties of 700 MHz, β = 0.42 elliptical cavity for high current ...

    Indian Academy of Sciences (India)

    Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, ... has been taken up as a part of the accelerator-driven subcritical system project. ... cavity's peak electric and magnetic fields, power dissipation Pc, quality factor Q and.

  6. Compact vibration isolation and suspension for Australian International Gravitational Observatory: Performance in a 72 m Fabry Perot cavity

    Science.gov (United States)

    Barriga, P.; Dumas, J. C.; Woolley, A. A.; Zhao, C.; Blair, D. G.

    2009-11-01

    This paper describes the first demonstration of vibration isolation and suspension systems, which have been developed with view to application in the proposed Australian International Gravitational Observatory. In order to achieve optimal performance at low frequencies new components and techniques have been combined to create a compact advanced vibration isolator structure. The design includes two stages of horizontal preisolation and one stage of vertical preisolation with resonant frequencies ˜100 mHz. The nested structure facilitates a compact design and enables horizontal preisolation stages to be configured to create a superspring configuration, where active feedback can enable performance close to the limit set by seismic tilt coupling. The preisolation stages are combined with multistage three-dimensional (3D) pendulums. Two isolators suspending mirror test masses have been developed to form a 72 m optical cavity with finesse ˜700 in order to test their performance. The suitability of the isolators for use in suspended optical cavities is demonstrated through their ease of locking, long term stability, and low residual motion. An accompanying paper presents the local control system and shows how simple upgrades can substantially improve residual motion performance.

  7. On niobium sputter coated cavities

    International Nuclear Information System (INIS)

    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

  8. High Performance Networks for High Impact Science

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Mary A.; Bair, Raymond A.

    2003-02-13

    This workshop was the first major activity in developing a strategic plan for high-performance networking in the Office of Science. Held August 13 through 15, 2002, it brought together a selection of end users, especially representing the emerging, high-visibility initiatives, and network visionaries to identify opportunities and begin defining the path forward.

  9. Possible influence of surface oxides on the optical response of high-purity niobium material used in the fabrication of superconducting radio frequency cavity

    Science.gov (United States)

    Singh, Nageshwar; Deo, M. N.; Roy, S. B.

    2016-09-01

    We have investigated the possible influence of surface oxides on the optical properties of a high-purity niobium (Nb) material for fabrication of superconducting radio frequency (SCRF) cavities. Various peaks in the infrared region were identified using Fourier transform infrared and Raman spectroscopy. Optical response functions such as complex refractive index, dielectric and conductivity of niobium were compared with the existing results on oxides free Nb and Cu. It was observed that the presence of a mixture of niobium-oxides, and probably near other surface impurities, appreciably influence the conducting properties of the material causing deviation from the typical metallic characteristics. In this way, the key result of this work is the observation, identification of vibrational modes of some of surface complexes and study of its influences on the optical responses of materials. This method of spectroscopic investigation will help in understanding the origin of degradation of performance of SCRF cavities.

  10. Possible influence of surface oxides on the optical response of high-purity niobium material used in the fabrication of superconducting radio frequency cavity

    International Nuclear Information System (INIS)

    Singh, Nageshwar; Deo, M.N.; Roy, S.B.

    2016-01-01

    We have investigated the possible influence of surface oxides on the optical properties of a high-purity niobium (Nb) material for fabrication of superconducting radio frequency (SCRF) cavities. Various peaks in the infrared region were identified using Fourier transform infrared and Raman spectroscopy. Optical response functions such as complex refractive index, dielectric and conductivity of niobium were compared with the existing results on oxides free Nb and Cu. It was observed that the presence of a mixture of niobium-oxides, and probably near other surface impurities, appreciably influence the conducting properties of the material causing deviation from the typical metallic characteristics. In this way, the key result of this work is the observation, identification of vibrational modes of some of surface complexes and study of its influences on the optical responses of materials. This method of spectroscopic investigation will help in understanding the origin of degradation of performance of SCRF cavities.

  11. Possible influence of surface oxides on the optical response of high-purity niobium material used in the fabrication of superconducting radio frequency cavity

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Nageshwar [Magnetic and Superconducting Materials Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, M.P. (India); Deo, M.N. [High Pressure & Synchrotron Radiation Physics Division, BARC, Mumbai 400085 (India); Roy, S.B. [Magnetic and Superconducting Materials Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, M.P. (India)

    2016-09-11

    We have investigated the possible influence of surface oxides on the optical properties of a high-purity niobium (Nb) material for fabrication of superconducting radio frequency (SCRF) cavities. Various peaks in the infrared region were identified using Fourier transform infrared and Raman spectroscopy. Optical response functions such as complex refractive index, dielectric and conductivity of niobium were compared with the existing results on oxides free Nb and Cu. It was observed that the presence of a mixture of niobium-oxides, and probably near other surface impurities, appreciably influence the conducting properties of the material causing deviation from the typical metallic characteristics. In this way, the key result of this work is the observation, identification of vibrational modes of some of surface complexes and study of its influences on the optical responses of materials. This method of spectroscopic investigation will help in understanding the origin of degradation of performance of SCRF cavities.

  12. The influence of chemical treatments on the superconducting properties of technical niobium materials and their effect on the performance of superconducting radio frequency cavities

    International Nuclear Information System (INIS)

    Roy, S B; Sahni, V C; Myneni, G R

    2009-01-01

    We present the results of a study of superconducting response in the niobium materials used in the fabrication of high accelerating gradient (>25 MV m -1 ) superconducting radio frequency (SC-RF) cavities. These results clearly show that the typical surface chemical treatment deployed during the fabrication of SC-RF cavities affects the superconducting properties of pure niobium materials. Such SC-RF cavities operating at 2 K are often found to show anomalous RF losses, causing either a strong degradation of the quality factor or a thermal breakdown for cavity magnetic fields between 1 and 1.5 kOe. The results of our study suggest a correlation between the field for the first flux-line penetration in these chemically treated technical niobium materials and the reported onset field of anomalous losses in the SC-RF cavities.

  13. The influence of chemical treatments on the superconducting properties of technical niobium materials and their effect on the performance of superconducting radio frequency cavities

    Science.gov (United States)

    Roy, S. B.; Myneni, G. R.; Sahni, V. C.

    2009-10-01

    We present the results of a study of superconducting response in the niobium materials used in the fabrication of high accelerating gradient (>25 MV m-1) superconducting radio frequency (SC-RF) cavities. These results clearly show that the typical surface chemical treatment deployed during the fabrication of SC-RF cavities affects the superconducting properties of pure niobium materials. Such SC-RF cavities operating at 2 K are often found to show anomalous RF losses, causing either a strong degradation of the quality factor or a thermal breakdown for cavity magnetic fields between 1 and 1.5 kOe. The results of our study suggest a correlation between the field for the first flux-line penetration in these chemically treated technical niobium materials and the reported onset field of anomalous losses in the SC-RF cavities.

  14. Fabrication of elliptical SRF cavities

    Science.gov (United States)

    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

  15. Photocathodes inside superconducting cavities. Studies on the feasibility of a superconducting photoelectron source of high brightness. External report

    International Nuclear Information System (INIS)

    Michalke, A.

    1992-01-01

    We have done studies and experiments to explore the feasibility of a photoemission RF gun with a superconducting accelerator cavity. This concept promises to provide an electron beam of high brightness in continuous operation. It is thus of strong interest for a free-electron-laser or a linear collider based on a superconducting accelerator. In a first step we studied possible technical solutions for its components, especially the material of the photocathode and the geometrical shape of the cavity. Based on these considerations, we developed the complete design for a prototype electron source. The cathode material was chosen to be alkali antimonide. In spite of its sensitivity, it seems to be the best choice for a gun with high average current due to its high quantum efficiency. The cavity shape was at first a reentrant-type single cell of 500 MHz. It is now replaced by a more regular two-and-half cell shape, an independent half cell added for emittance correction. Its beam dynamics properties are investigated by numerical simulations; we estimated a beam brightness of about 5x10 11 A/(m.rad) 2 . But the mutual interactions between alkali antimonide photocathode and superconducting cavity must be investigated experimentally, because they are completely unkown. (orig.)

  16. High temperature dielectric properties of spent adsorbent with zinc sulfate by cavity perturbation technique

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Guo [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming, Yunnan 650093 (China); National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093 (China); Liu, Chenhui [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming, Yunnan 650093 (China); National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093 (China); Faculty of Chemistry and Environment, Yunnan Minzu University, Kunming, Yunnan 650093 (China); Zhang, Libo, E-mail: libozhang77@163.com [State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093 (China); Key Laboratory of Unconventional Metallurgy, Ministry of Education, Kunming, Yunnan 650093 (China); National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093 (China); and others

    2017-05-15

    Highlights: • Cavity perturbation technique is employed to measure the dielectric properties. • Microwave absorption capability of ZnO is poor from 20 °C to 850 °C. • Dielectric properties of spent absorbent and zinc sulfate are influenced by temperature especially in high temperature stage. • Penetration depths and heating curve indicate spent adsorbent and ZnO·2ZnSO{sub 4}, ZnSO{sub 4} are excellent microwave absorber. • The pore structures of spent adsorbent are improved significantly by microwave-regeneration directly. - Abstract: Dielectric properties of spent adsorbent with zinc sulfate are investigated by cavity perturbation technique at 2450 MHz from 20 °C to approximately 1000 °C. Two weight loss stages are observed for spent adsorbent by thermogravimetric-differential scanning calorimeter (TG-DSC) analysis, and zinc sulfate is decomposed to ZnO·2ZnSO{sub 4} and ZnO at about 750 °C and 860 °C. Microwave absorption capability of ZnSO{sub 4} increases with increasing temperature and declines after ZnO generation on account of the poor dielectric properties. Dielectric properties of spent adsorbent are dependent on apparent density and noticed an interestingly linearly relationship at room temperature. The three parameters increase gently from 20 °C to 400 °C, but a sharp increase both in real part and imaginary part are found subsequently due to the volatiles release and regeneration of carbon. And material conductivity is improved, which contributes to the π-electron conduction appearance. Relationship between penetration depth and temperature further elaborate spent adsorbent is an excellent microwave absorber and the microwave absorption capability order of zinc compounds is ZnO·2ZnSO{sub 4}, ZnSO{sub 4} and ZnO. Heating characteristics suggest that heating rate is related with dielectric properties of materials. The pore structures of spent adsorbent are improved significantly and the surface is smoother after microwave-regeneration.

  17. High-power, format-flexible, 885-nm vertical-cavity surface-emitting laser arrays

    Science.gov (United States)

    Wang, Chad; Talantov, Fedor; Garrett, Henry; Berdin, Glen; Cardellino, Terri; Millenheft, David; Geske, Jonathan

    2013-03-01

    High-power, format flexible, 885 nm vertical-cavity surface-emitting laser (VCSEL) arrays have been developed for solid-state pumping and illumination applications. In this approach, a common VCSEL size format was designed to enable tiling into flexible formats and operating configurations. The fabrication of a common chip size on ceramic submount enables low-cost volume manufacturing of high-power VCSEL arrays. This base VCSEL chip was designed to be 5x3.33 mm2, and produced up to 50 Watts of peak continuous wave (CW) power. To scale to higher powers, multiple chips can be tiled into a combination of series or parallel configurations tailored to the application driver conditions. In actively cooled CW operation, the VCSEL array chips were packaged onto a single water channel cooler, and we have demonstrated 0.5x1, 1x1, and 1x3 cm2 formats, producing 150, 250, and 500 Watts of peak power, respectively, in under 130 A operating current. In QCW operation, the 1x3 cm2 VCSEL module, which contains 18 VCSEL array chips packaged on a single water cooler, produced over 1.3 kW of peak power. In passively cooled packages, multiple chip configurations have been developed for illumination applications, producing over 300 Watts of peak power in QCW operating conditions. These VCSEL chips use a substrate-removed structure to allow for efficient thermal heatsinking to enable high-power operation. This scalable, format flexible VCSEL architecture can be applied to wavelengths ranging from 800 to 1100 nm, and can be used to tailor emission spectral widths and build high-power hyperspectral sources.

  18. Simulations of fast crab cavity failures in the high luminosity Large Hadron Collider

    Directory of Open Access Journals (Sweden)

    Bruce Yee-Rendon

    2014-05-01

    Full Text Available Crab cavities (CCs are a key ingredient of the high luminosity Large Hadron Collider (HL-LHC project for increasing the luminosity of the LHC. At KEKB, CCs have exhibited abrupt changes of phase and voltage during a time period of the order of a few LHC turns and considering the significant stored energy in the HL-LHC beam, CC failures represent a serious threat in regard to LHC machine protection. In this paper, we discuss the effect of CC voltage or phase changes on a time interval similar to, or longer than, the one needed to dump the beam. The simulations assume a quasistationary-state distribution to assess the particles losses for the HL-LHC. These distributions produce beam losses below the safe operation threshold for Gaussian tails, while, for non-Gaussian tails are on the same order of the limit. Additionally, some mitigation strategies are studied for reducing the damage caused by the CC failures.

  19. Finite volume simulation of 2-D steady square lid driven cavity flow at high reynolds numbers

    Directory of Open Access Journals (Sweden)

    K. Yapici

    2013-12-01

    Full Text Available In this work, computer simulation results of steady incompressible flow in a 2-D square lid-driven cavity up to Reynolds number (Re 65000 are presented and compared with those of earlier studies. The governing flow equations are solved by using the finite volume approach. Quadratic upstream interpolation for convective kinematics (QUICK is used for the approximation of the convective terms in the flow equations. In the implementation of QUICK, the deferred correction technique is adopted. A non-uniform staggered grid arrangement of 768x768 is employed to discretize the flow geometry. Algebraic forms of the coupled flow equations are then solved through the iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equation algorithm. The outlined computational methodology allows one to meet the main objective of this work, which is to address the computational convergence and wiggled flow problems encountered at high Reynolds and Peclet (Pe numbers. Furthermore, after Re > 25000 additional vortexes appear at the bottom left and right corners that have not been observed in earlier studies.

  20. Hydroforming of Tesla Cavities at Desy

    International Nuclear Information System (INIS)

    Singer, W.; Kaiser, H.; Singer, X.; Gonin, I.; Zhelezov, I.; Khabibullin, T.; Kneisel, P.; Saito, K.

    2000-01-01

    Since several years the development of seamless niobium cavity fabrication by hydro forming is being pursued at DESY. This technique offers the possibility of lower cost of fabrication and perhaps better rf performance of the cavities because of the elimination of electron-beam welds, which in the standard fabrication technique have sometimes lead to inferior cavity performance due to defects. Several single cell 1300 MHz cavities have been formed from high purity seamless niobium tubes, which are under computer control expanded with internal pressure while simultaneously being swaged axially. The seamless tubes have been made by either back extrusion and flow forming or by spinning or deep drawing. Standard surface treatment techniques such as high temperature post purification, buffered chemical polishing (BCP), electropolishing (EP) and high pressure ultra pure water rinsing (HPR) have been applied to these cavities. The cavities exhibited high Q - values of 2 x 10 10 at 2K and residual resistances as low as 3 n(Omega) after the removal of a surface layer of app. 100 (micro)m by BCP. Surprisingly, even at high gradients up to the maximum measured values of E acc ∼ 33 MV/m the Q-value did not decrease in the absence of field emission as often observed. After electropolishing of additional 100 (micro)m one of the cavities reached an accelerating gradient of E acc (ge) 42 MV/m

  1. Fabrication and Final Field Tuning of Copper Cavity Models for a High-Current SRF ERL at 703.75 MHz

    CERN Document Server

    Cole, Michael; Burger, Al; Falletta, Michael; Holmes, Douglas; Peterson, Ed; Wong, Robert

    2005-01-01

    Advanced Energy Systems is currently under contract to BNL to fabricate a five cell superconducting cavity and cryomodule for the RHIC eCooler SRF Energy Recovery Linac (ERL) program.* The cavity is designed and optimized for ampere class SRF ERL service. As part of this program, we have fabricated two low power copper models of the RF cavities. During the fabrication process a series of frequency measurements were made and compared to the frequency expected at that point in the fabrication process. Where possible, the cavity was modified either before or during, the next fabrication step to tune the cavity frequency toward the target frequency. Following completion of the cavities they were tuned for field flatness and frequency. This paper will review the measurements made, frequency tuning performed, and discuss discrepancies between the expected and measured results. We will also review the as fabricated field profiles and the results of the tuning steps. Further, the cost and benefits of extensive in pro...

  2. RavenDB high performance

    CERN Document Server

    Ritchie, Brian

    2013-01-01

    RavenDB High Performance is comprehensive yet concise tutorial that developers can use to.This book is for developers & software architects who are designing systems in order to achieve high performance right from the start. A basic understanding of RavenDB is recommended, but not required. While the book focuses on advanced topics, it does not assume that the reader has a great deal of prior knowledge of working with RavenDB.

  3. High-Q operation of superconducting rf cavities: Potential impact of thermocurrents on the rf surface resistance

    Directory of Open Access Journals (Sweden)

    J.-M. Vogt

    2015-04-01

    Full Text Available For many new accelerator applications, superconducting radio frequency systems are the enabling technology. In particular for CW applications, much effort is being expended to minimize the power dissipation (surface resistance of niobium cavities. Starting in 2009, we suggested a means of reducing the residual resistance by performing a thermal cycle [O. Kugeler et al., in Proceedings of the 14th International Conference on RF Superconductivity (2009, p. 352], a procedure of warming up a cavity after initial cooldown to about 20 K and cooling it down again. In subsequent studies [J. M. Vogt, O. Kugeler, and J. Knobloch, Phys. Rev. ST Accel. Beams 16, 102002 (2013], this technique was used to manipulate the residual resistance by more than a factor of 2. It was postulated that thermocurrents during cooldown generate additional trapped magnetic flux that impacts the cavity quality factor. Here, we present a more extensive study that includes measurements of two additional passband modes and that confirms the effect. In this paper, we also discuss simulations that support the claim. While the layout of the cavity LHe tank system is cylindrically symmetric, we show that the temperature dependence of the material parameters results in a nonsymmetric current distribution. Hence a significant amount of magnetic flux can be generated at the rf surface.

  4. High-Performance Operating Systems

    DEFF Research Database (Denmark)

    Sharp, Robin

    1999-01-01

    Notes prepared for the DTU course 49421 "High Performance Operating Systems". The notes deal with quantitative and qualitative techniques for use in the design and evaluation of operating systems in computer systems for which performance is an important parameter, such as real-time applications......, communication systems and multimedia systems....

  5. Dental cavities

    Science.gov (United States)

    ... 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 ...

  6. High resolution and high precision absorption spectroscopy using high finesse cavities: application to the study of molecules with atmospheric interest; Cavites de haute finesse pour la spectroscopie d'absorption haute sensibilite et haute precision: application a l'etude de molecules d'interet atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Motto-Ros, V.

    2005-12-15

    High finesse cavities are used to measure very weak absorption features. Two different methodologies are investigated and applied to the study of molecules with atmospheric interest. First, Continuous Wave - Cavity Ring Down Spectroscopy (CW-CRDS) is used to study the atmospheric spectra of water vapour in the near infrared range. These measurements are performed for temperature and pressure of atmospheric relevance for DIAL applications (Differential Absorption Lidar). This study, financed by the European Space Agency (ESA), goes with the WALES mission (Water Vapour Lidar Experiment in Space). The experimental setup was conceived in order to control pressure, temperature and relative humidity conditions. A particular attention is done to characterize and describe the spectrometer. Then, measurements of red Oxygen B band are performed to demonstrate the huge performance of Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS). The desired optical feedback is obtained by light injection into the high finesse cavity through a glass plate placed inside the cavity and closed to the Brewster angle. We show a measurement dynamical range of 5 orders of magnitude (10{sup -5} to 10{sup -10} /cm) and a sensitivity of 10{sup -10} /cm/{radical} Hz. Also, sampling absorption spectra by the super linear cavity frequency comb allows very precise frequency measurements. This is demonstrated by the determination of Oxygen pressure shifts with an absolute accuracy of around 5 x 10{sup -5} cm{sup -1}/atm. To our knowledge, we provide the highest accuracy ever reported for this parameter. (author)

  7. High resolution and high precision absorption spectroscopy using high finesse cavities: application to the study of molecules with atmospheric interest; Cavites de haute finesse pour la spectroscopie d'absorption haute sensibilite et haute precision: application a l'etude de molecules d'interet atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Motto-Ros, V

    2005-12-15

    High finesse cavities are used to measure very weak absorption features. Two different methodologies are investigated and applied to the study of molecules with atmospheric interest. First, Continuous Wave - Cavity Ring Down Spectroscopy (CW-CRDS) is used to study the atmospheric spectra of water vapour in the near infrared range. These measurements are performed for temperature and pressure of atmospheric relevance for DIAL applications (Differential Absorption Lidar). This study, financed by the European Space Agency (ESA), goes with the WALES mission (Water Vapour Lidar Experiment in Space). The experimental setup was conceived in order to control pressure, temperature and relative humidity conditions. A particular attention is done to characterize and describe the spectrometer. Then, measurements of red Oxygen B band are performed to demonstrate the huge performance of Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS). The desired optical feedback is obtained by light injection into the high finesse cavity through a glass plate placed inside the cavity and closed to the Brewster angle. We show a measurement dynamical range of 5 orders of magnitude (10{sup -5} to 10{sup -10} /cm) and a sensitivity of 10{sup -10} /cm/{radical} Hz. Also, sampling absorption spectra by the super linear cavity frequency comb allows very precise frequency measurements. This is demonstrated by the determination of Oxygen pressure shifts with an absolute accuracy of around 5 x 10{sup -5} cm{sup -1}/atm. To our knowledge, we provide the highest accuracy ever reported for this parameter. (author)

  8. MEASUREMENT OF THE HIGH-FIELD Q-DROP IN A LARGE-GRAIN NIOBIUM CAVITY FOR DIFFERENT OXIDATION PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Gianluigi Ciovati; Peter Kneisel; Alex Gurevich

    2008-01-23

    In this contribution, we present the results from a series of RF tests at 1.7 K and 2.0 K on a single-cell cavity made of high-purity large (with area of the order of few cm2) grain niobium which underwent various oxidation processes. After initial buffered chemical polishing, anodization, baking in pure oxygen atmosphere and baking in air up to 180 °C was applied with the objective of clearly identifying the role of oxygen and the oxide layer on the Q-drop. During each rf test a temperature mapping system was used allowing to measure the local temperature rise of the cavity outer surface due to RF losses, which gives information about the losses location, their field dependence and space distribution on the RF surface. The results confirmed that the depth affected by baking is about 20 – 30 nm from the surface and showed that the Q-drop did not re-appear in a previously baked cavity by further baking at 120 °C in pure oxygen atmosphere or in air up to 180 °C. A statistic of the position of the “hot-spots” on the cavity surface showed that grain-boundaries are not the preferred location. An interesting correlation was found between the Q-drop onset, the quench field and the low-field energy gap, which supports the hypothesis of thermo-magnetic instability governing the Q-drop and the baking effect.

  9. MEASUREMENT OF THE HIGH-FIELD Q-DROP IN A LARGE-GRAIN NIOBIUM CAVITY FOR DIFFERENT OXIDATION PROCESSES

    International Nuclear Information System (INIS)

    Gianluigi Ciovati; Peter Kneisel; Alex Gurevich

    2008-01-01

    In this contribution, we present the results from a series of RF tests at 1.7 K and 2.0 K on a single-cell cavity made of high-purity large (with area of the order of few cm2) grain niobium which underwent various oxidation processes. After initial buffered chemical polishing, anodization, baking in pure oxygen atmosphere and baking in air up to 180 C was applied with the objective of clearly identifying the role of oxygen and the oxide layer on the Q-drop. During each rf test a temperature mapping system was used allowing to measure the local temperature rise of the cavity outer surface due to RF losses, which gives information about the losses location, their field dependence and space distribution on the RF surface. The results confirmed that the depth affected by baking is about 20-30 nm from the surface and showed that the Q-drop did not re-appear in a previously baked cavity by further baking at 120 C in pure oxygen atmosphere or in air up to 180 C. A statistic of the position of the ''hot-spots'' on the cavity surface showed that grain-boundaries are not the preferred location. An interesting correlation was found between the Q-drop onset, the quench field and the low-field energy gap, which supports the hypothesis of thermomagnetic instability governing the Q-drop and the baking effect.

  10. A semi-analytical model of a time reversal cavity for high-amplitude focused ultrasound applications

    Science.gov (United States)

    Robin, J.; Tanter, M.; Pernot, M.

    2017-09-01

    Time reversal cavities (TRC) have been proposed as an efficient approach for 3D ultrasound therapy. They allow the precise spatio-temporal focusing of high-power ultrasound pulses within a large region of interest with a low number of transducers. Leaky TRCs are usually built by placing a multiple scattering medium, such as a random rod forest, in a reverberating cavity, and the final peak pressure gain of the device only depends on the temporal length of its impulse response. Such multiple scattering in a reverberating cavity is a complex phenomenon, and optimisation of the device’s gain is usually a cumbersome process, mostly empirical, and requiring numerical simulations with extremely long computation times. In this paper, we present a semi-analytical model for the fast optimisation of a TRC. This model decouples ultrasound propagation in an empty cavity and multiple scattering in a multiple scattering medium. It was validated numerically and experimentally using a 2D-TRC and numerically using a 3D-TRC. Finally, the model was used to determine rapidly the optimal parameters of the 3D-TRC which had been confirmed by numerical simulations.

  11. Highly Sensitive Measurements of the Dark Current of Superconducting Cavities for TESLA Using a SQUID Based Cryogenic Current Comparator

    CERN Document Server

    Vodel, W; Nietzsche, S

    2004-01-01

    This contribution presents a Cryogenic Current Comparator (CCC) as an excellent tool for detecting dark currents generated, e.g. by superconducting cavities for the upcoming TESLA project (X-FEL) at DESY. To achieve the maximum possible energy the gradient of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The undesired field emission of electrons (so-called dark current) of the superconducting RF cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a highly sensitive LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measu...

  12. Geometry Effects on Multipole Components and Beam Optics in High-Velocity Multi-Spoke Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Hopper, Christopher S. [ODU, JLAB; Deitrick, Kirsten E. [ODU, JLAB; Delayen, Jean R. [ODU, JLAB

    2013-12-01

    Velocity-of-light, multi-spoke cavities are being proposed to accelerate electrons in a compact light-source. There are strict requirements on the beam quality which require that the linac have only small non-uniformities in the accelerating field. Beam dynamics simulations have uncovered varying levels of focusing and defocusing in the proposed cavities, which is dependent on the geometry of the spoke in the vicinity of the beam path. Here we present results for the influence different spoke geometries have on the multipole components of the accelerating field and how these components, in turn, impact the simulated beam properties.

  13. Nb3Sn for Radio Frequency Cavities

    International Nuclear Information System (INIS)

    Godeke, A.

    2006-01-01

    In this article, the suitability of Nb3Sn to improve the performance of superconducting Radio-Frequency (RF) cavities is discussed. The use of Nb3Sn in RF cavities is recognized as an enabling technology to retain a very high cavity quality factor (Q0) at 4.2 K and to significantly improve the cavity accelerating efficiency per unit length (Eacc). This potential arises through the fundamental properties of Nb3Sn. The properties that are extensively characterized in the literature are, however, mainly related to improvements in current carrying capacity (Jc) in the vortex state. Much less is available for the Meissner state, which is of key importance to cavities. Relevant data, available for the Meissner state is summarized, and it is shown how this already validates the use of Nb3Sn. In addition, missing knowledge is highlighted and suggestions are given for further Meissner state specific research

  14. Hydroforming of superconducting TESLA cavities

    International Nuclear Information System (INIS)

    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)

  15. The vertical-cavity surface-emitting laser incorporating a high contrast grating mirror as a sensing device

    Science.gov (United States)

    Marciniak, Magdalena; Gebski, Marcin; Piskorski, Łukasz; Dems, Maciej; Wasiak, M.; Panajotov, Krassimir; Lott, James A.; Czyszanowski, Tomasz

    2018-02-01

    We propose a novel optical sensing system based on one device that both emits and detects light consisting of a verticalcavity surface-emitting laser (VCSEL) incorporating an high contrast grating (HCG) as a top mirror. Since HCGs can be very sensitive to the optical properties of surrounding media, they can be used to detect gases and liquid. The presence of a gas or a liquid around an HCG mirror causes changes of the power reflectance of the mirror, which corresponds to changes of the VCSEL's cavity quality factor and current-voltage characteristic. By observation of the current-voltage characteristic we can collect information about the medium around the HCG. In this paper we investigate how the properties of the HCG mirror depend on the refractive index of the HCG surroundings. We present results of a computer simulation performed with a three-dimensional fully vectorial model. We consider silicon HCGs on silica and designed for a 1300 nm VCSEL emission wavelength. We demonstrate that our approach can be applied to other wavelengths and material systems.

  16. Laboratory testing of joints between windows and highly insulated cavity walls. Investigations of tightness against rain and wind

    Energy Technology Data Exchange (ETDEWEB)

    Kjaer, A

    1983-10-01

    In the Danish energy research programme, 1EFP 80, a number of laboratory tests have been carried out on models of highly insulated cavity brick walls in order to study rain- and wind tightness of the joints between windows and such walls. Tests have been carried out with joints tightened only with a rain barrier as well as with joints according to the two stage joint principle. In the exterior part of the joint has in both cases been used a mortar, and expanding gasket, an EPDM-profile and wooden battens. Further an experiment has been carried out on a plastic window, where mastic was used as well in the exterior as the interior part of the joint. The findings were that a two-stage joint gives the best performance as well regarding air tightness as rain tightness. Further the experiments have shown that a window frame should have a depth of at least 90 mm in order to design a joint between window and wall, which is satisfactory as well regarding thermal insulation as resistance to rain and wind.

  17. Superconducting Radio-Frequency Cavities for Low-Beta Particle Accelerators

    Science.gov (United States)

    Kelly, Michael

    2012-01-01

    High-power proton and ion linac projects based on superconducting accelerating cavities are driving a worldwide effort to develop and build superconducting cavities for beta < 1. Laboratories and institutions building quarter-wave, halfwave and single- or multi-spoke cavities continue to advance the state of the art for this class of cavities, and the common notion that low-beta SRF cavities fill a need in niche applications and have low performance is clearly no longer valid. This article reviews recent developments and results for SC cavity performance for cavities with beta up to approximately 0.5. The considerable ongoing effort on reduced beta elliptical cell cavities is not discussed. An overview of associated subsystems required to operate low-beta cavities, including rf power couplers and fast and slow tuners, is presented.

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

    International Nuclear Information System (INIS)

    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. Resonant excitation of high order modes in the 3.9 GHz cavity of the Linac Coherent Light Source

    Directory of Open Access Journals (Sweden)

    A. Lunin

    2018-02-01

    Full Text Available Construction of the Linac Coherent Light Source II (LCLS-II is underway for the world’s first hard x-ray free-electron laser. A central part of the LCLS-II project is a 4 GeV superconducting radio frequency electron linac that will operate in the continuous wave (cw mode. The linac is segmented into four sections named as L0, L1, L2, and L3. Two 3.9 GHz cryomodules, each housing of eight third-harmonic cavities similar to the cavities developed for the European X-ray Free Electron Laser (XFEL, will be used in section L1 of the linac for linearizing the longitudinal beam profile. In this paper, we present a study of trapped high order modes (HOMs excited by a cw electron beam in the third-harmonic cavities of the LCLS-II linac. A detailed comparison of the original XFEL design and the LCLS-II design with a modified end group is performed in order to estimate the effect of a reduced beam pipe aperture on the efficiency of HOM damping. Furthermore, we apply a statistical analysis of the eigenmode spectrum for the estimation of the probability of resonant HOM losses and influence of HOMs on beam dynamics.

  20. The LHC superconducting cavities

    CERN Document Server

    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.

  1. Cavity ring-down technique for measurement of reflectivity of high ...

    Indian Academy of Sciences (India)

    Laser & Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400 085,. India. *Corresponding author. E-mail: gsridhar@barc.gov.in. Abstract. A simple, accurate and reliable method for measuring the reflectivity of laser- ... Keywords. Cavity ring-down method; reflectivity measurement; optical resonator.

  2. Dynamical dispersion engineering in coupled vertical cavities employing a high-contrast grating

    DEFF Research Database (Denmark)

    Taghizadeh, Alireza; Chung, Il-Sug

    2017-01-01

    , including a case capable of dynamically controlling the photon’s effective mass to a large extent while keeping the resonance frequency same. We believe that full-control and dynamical-tuning of the photon’s effective mass may enable new possibilities for cavity quantum electrodynamics studies...

  3. Cavity ring-down technique for measurement of reflectivity of high

    Indian Academy of Sciences (India)

    grade mirrors ( > 99.5 %) based on cavity ring-down (CRD) technique has been success-fully demonstrated in our laboratory using a pulsed Nd:YAG laser. A fast photomultiplier tube with an oscilloscope was used to detect and analyse the CRD ...

  4. The Dimensions of the Orbital Cavity Based on High-Resolution Computed Tomography of Human Cadavers

    DEFF Research Database (Denmark)

    Felding, Ulrik Ascanius; Bloch, Sune Land; Buchwald, Christian von

    2016-01-01

    for surface area. To authors' knowledge, this study is the first to have measured the entire surface area of the orbital cavity.The volume and surface area of the orbital cavity were estimated in computed tomography scans of 11 human cadavers using unbiased stereological sampling techniques. The mean (± SD......) total volume and total surface area of the orbital cavities was 24.27 ± 3.88 cm and 32.47 ± 2.96 cm, respectively. There was no significant difference in volume (P = 0.315) or surface area (P = 0.566) between the 2 orbital cavities.The stereological technique proved to be a robust and unbiased method...... that may be used as a gold standard for comparison with automated computer software. Future imaging studies in blow-out fracture patients may be based on individual and relative calculation involving both herniated volume and fractured surface area in relation to the total volume and surface area...

  5. RF properties of 700 MHz, β= 0.42 elliptical cavity for high current ...

    Indian Academy of Sciences (India)

    ADSS) that will be mainly utilized for the transmutation of nuclear waste and enrichment of U233. Design and development of superconducting medium velocity cavity has been taken up as a part of the accelerator-driven subcritical system ...

  6. Identifying High Performance ERP Projects

    OpenAIRE

    Stensrud, Erik; Myrtveit, Ingunn

    2002-01-01

    Learning from high performance projects is crucial for software process improvement. Therefore, we need to identify outstanding projects that may serve as role models. It is common to measure productivity as an indicator of performance. It is vital that productivity measurements deal correctly with variable returns to scale and multivariate data. Software projects generally exhibit variable returns to scale, and the output from ERP projects is multivariate. We propose to use Data Envelopment ...

  7. Image-guided intensity modulated radiotherapy with helical tomotherapy for postoperative treatment of high-risk oral cavity cancer

    Directory of Open Access Journals (Sweden)

    Chen Yu-Jen

    2011-01-01

    Full Text Available Abstract Background The aim of this study was to assess the treatment results and toxicity profiles of helical tomotherapy (HT for postoperative high-risk oral cavity cancer. Methods From December 6, 2006 through October 9, 2009, 19 postoperative high-risk oral cavity cancer patients were enrolled. All of the patients received HT with (84% or without (16% chemotherapy. Results The median follow-up time was 17 months. The 2-year overall survival, disease-free survival, locoregional control, and distant metastasis-free rates were 94%, 84%, 92%, and 94%, respectively. The package of overall treatment time > 13 wk, the interval between surgery and radiation ≤ 6 wk, and the overall treatment time of radiation ≤ 7 wk was 21%, 84%, and 79%, respectively. The percentage of grade 3 mucositis, dermatitis, and leucopenia was 42%, 5% and 5%, respectively. Conclusions HT achieved encouraging clinical outcomes for postoperative high-risk oral cavity cancer patients with high compliance. A long-term follow-up study is needed to confirm these preliminary findings.

  8. Image-guided intensity modulated radiotherapy with helical tomotherapy for postoperative treatment of high-risk oral cavity cancer

    International Nuclear Information System (INIS)

    Hsieh, Chen-Hsi; Hsieh, Yen-Ping; Lin, Shoei Long; Chen, Chun-Yi; Chen, Chien-An; Shueng, Pei-Wei; Kuo, Ying-Shiung; Liao, Li-Jen; Hu, Kawang-Yu; Lin, Shih-Chiang; Wu, Le-Jung; Lin, Yu-Chin; Chen, Yu-Jen; Wang, Li-Ying

    2011-01-01

    The aim of this study was to assess the treatment results and toxicity profiles of helical tomotherapy (HT) for postoperative high-risk oral cavity cancer. From December 6, 2006 through October 9, 2009, 19 postoperative high-risk oral cavity cancer patients were enrolled. All of the patients received HT with (84%) or without (16%) chemotherapy. The median follow-up time was 17 months. The 2-year overall survival, disease-free survival, locoregional control, and distant metastasis-free rates were 94%, 84%, 92%, and 94%, respectively. The package of overall treatment time > 13 wk, the interval between surgery and radiation ≤ 6 wk, and the overall treatment time of radiation ≤ 7 wk was 21%, 84%, and 79%, respectively. The percentage of grade 3 mucositis, dermatitis, and leucopenia was 42%, 5% and 5%, respectively. HT achieved encouraging clinical outcomes for postoperative high-risk oral cavity cancer patients with high compliance. A long-term follow-up study is needed to confirm these preliminary findings

  9. INL High Performance Building Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Jennifer D. Morton

    2010-02-01

    High performance buildings, also known as sustainable buildings and green buildings, are resource efficient structures that minimize the impact on the environment by using less energy and water, reduce solid waste and pollutants, and limit the depletion of natural resources while also providing a thermally and visually comfortable working environment that increases productivity for building occupants. As Idaho National Laboratory (INL) becomes the nation’s premier nuclear energy research laboratory, the physical infrastructure will be established to help accomplish this mission. This infrastructure, particularly the buildings, should incorporate high performance sustainable design features in order to be environmentally responsible and reflect an image of progressiveness and innovation to the public and prospective employees. Additionally, INL is a large consumer of energy that contributes to both carbon emissions and resource inefficiency. In the current climate of rising energy prices and political pressure for carbon reduction, this guide will help new construction project teams to design facilities that are sustainable and reduce energy costs, thereby reducing carbon emissions. With these concerns in mind, the recommendations described in the INL High Performance Building Strategy (previously called the INL Green Building Strategy) are intended to form the INL foundation for high performance building standards. This revised strategy incorporates the latest federal and DOE orders (Executive Order [EO] 13514, “Federal Leadership in Environmental, Energy, and Economic Performance” [2009], EO 13423, “Strengthening Federal Environmental, Energy, and Transportation Management” [2007], and DOE Order 430.2B, “Departmental Energy, Renewable Energy, and Transportation Management” [2008]), the latest guidelines, trends, and observations in high performance building construction, and the latest changes to the Leadership in Energy and Environmental Design

  10. High performance fuel technology development

    Energy Technology Data Exchange (ETDEWEB)

    Koon, Yang Hyun; Kim, Keon Sik; Park, Jeong Yong; Yang, Yong Sik; In, Wang Kee; Kim, Hyung Kyu [KAERI, Daejeon (Korea, Republic of)

    2012-01-15

    {omicron} Development of High Plasticity and Annular Pellet - Development of strong candidates of ultra high burn-up fuel pellets for a PCI remedy - Development of fabrication technology of annular fuel pellet {omicron} Development of High Performance Cladding Materials - Irradiation test of HANA claddings in Halden research reactor and the evaluation of the in-pile performance - Development of the final candidates for the next generation cladding materials. - Development of the manufacturing technology for the dual-cooled fuel cladding tubes. {omicron} Irradiated Fuel Performance Evaluation Technology Development - Development of performance analysis code system for the dual-cooled fuel - Development of fuel performance-proving technology {omicron} Feasibility Studies on Dual-Cooled Annular Fuel Core - Analysis on the property of a reactor core with dual-cooled fuel - Feasibility evaluation on the dual-cooled fuel core {omicron} Development of Design Technology for Dual-Cooled Fuel Structure - Definition of technical issues and invention of concept for dual-cooled fuel structure - Basic design and development of main structure components for dual- cooled fuel - Basic design of a dual-cooled fuel rod.

  11. High Performance Bulk Thermoelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhifeng [Boston College, Chestnut Hill, MA (United States)

    2013-03-31

    Over 13 plus years, we have carried out research on electron pairing symmetry of superconductors, growth and their field emission property studies on carbon nanotubes and semiconducting nanowires, high performance thermoelectric materials and other interesting materials. As a result of the research, we have published 104 papers, have educated six undergraduate students, twenty graduate students, nine postdocs, nine visitors, and one technician.

  12. High performance in software development

    CERN Multimedia

    CERN. Geneva; Haapio, Petri; Liukkonen, Juha-Matti

    2015-01-01

    What are the ingredients of high-performing software? Software development, especially for large high-performance systems, is one the most complex tasks mankind has ever tried. Technological change leads to huge opportunities but challenges our old ways of working. Processing large data sets, possibly in real time or with other tight computational constraints, requires an efficient solution architecture. Efficiency requirements span from the distributed storage and large-scale organization of computation and data onto the lowest level of processor and data bus behavior. Integrating performance behavior over these levels is especially important when the computation is resource-bounded, as it is in numerics: physical simulation, machine learning, estimation of statistical models, etc. For example, memory locality and utilization of vector processing are essential for harnessing the computing power of modern processor architectures due to the deep memory hierarchies of modern general-purpose computers. As a r...

  13. High-order integral equation methods for problems of scattering by bumps and cavities on half-planes.

    Science.gov (United States)

    Pérez-Arancibia, Carlos; Bruno, Oscar P

    2014-08-01

    This paper presents high-order integral equation methods for the evaluation of electromagnetic wave scattering by dielectric bumps and dielectric cavities on perfectly conducting or dielectric half-planes. In detail, the algorithms introduced in this paper apply to eight classical scattering problems, namely, scattering by a dielectric bump on a perfectly conducting or a dielectric half-plane, and scattering by a filled, overfilled, or void dielectric cavity on a perfectly conducting or a dielectric half-plane. In all cases field representations based on single-layer potentials for appropriately chosen Green functions are used. The numerical far fields and near fields exhibit excellent convergence as discretizations are refined-even at and around points where singular fields and infinite currents exist.

  14. Efficient continuous-wave nonlinear frequency conversion in high-Q gallium nitride photonic crystal cavities on silicon

    Directory of Open Access Journals (Sweden)

    Mohamed Sabry Mohamed

    2017-03-01

    Full Text Available We report on nonlinear frequency conversion from the telecom range via second harmonic generation (SHG and third harmonic generation (THG in suspended gallium nitride slab photonic crystal (PhC cavities on silicon, under continuous-wave resonant excitation. Optimized two-dimensional PhC cavities with augmented far-field coupling have been characterized with quality factors as high as 4.4 × 104, approaching the computed theoretical values. The strong enhancement in light confinement has enabled efficient SHG, achieving a normalized conversion efficiency of 2.4 × 10−3 W−1, as well as simultaneous THG. SHG emission power of up to 0.74 nW has been detected without saturation. The results herein validate the suitability of gallium nitride for integrated nonlinear optical processing.

  15. Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

    Science.gov (United States)

    Lee, Jin-Hyuk; Kim, Dae-Hyun

    2014-10-01

    A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions.

  16. Resistivity changes in superconducting-cavity-grade Nb following high-energy proton irradiation

    International Nuclear Information System (INIS)

    Snead, C.L. Jr.; Hanson, A.; Greene, G.A.

    1997-01-01

    Niobium superconducting rf cavities are proposed for use in the proton LINAC accelerators for spallation-neutron applications. Because of accidental beam loss and continual halo losses along the accelerator path, concern for the degradation of the superconducting properties of the cavities with accumulating damage arises. Residual-resistivity-ratio (RRR) specimens of Nb, with a range of initial RRR's were irradiated at room temperature with protons at energies from 200 to 2000 MeV. Four-probe resistance measurements were made at room temperature and at 4.2 K both prior to and after irradiation. Nonlinear increases in resistivity simulate expected behavior in cavity material after extended irradiation, followed by periodic anneals to room temperature: For RRR = 316 material, irradiations to (2 - 3) x 10 15 p/cm 2 produce degradations up to the 10% level, a change that is deemed operationally acceptable. Without. periodic warming to room temperature, the accumulated damage energy would be up to a factor of ten greater, resulting in unacceptable degradations. Likewise, should higher-RRR material be used, for the same damage energy imparted, relatively larger percentage changes in the RRR will result

  17. Neo4j high performance

    CERN Document Server

    Raj, Sonal

    2015-01-01

    If you are a professional or enthusiast who has a basic understanding of graphs or has basic knowledge of Neo4j operations, this is the book for you. Although it is targeted at an advanced user base, this book can be used by beginners as it touches upon the basics. So, if you are passionate about taming complex data with the help of graphs and building high performance applications, you will be able to get valuable insights from this book.

  18. Conditioning of high voltage radio frequency cavities by using fuzzy logic in connection with rule based programming

    CERN Document Server

    Perréard, S

    1993-01-01

    Many processes are controlled by experts using some kind of mental model to decide actions and make conclusions. This model, based on heuristic knowledge, can often be conveniently represented in rules and has not to be particularly accurate. This is the case for the problem of conditioning high voltage radio-frequency cavities: the expert has to decide, by observing some criteria, if he can increase or if he has to decrease the voltage and by how much. A program has been implemented which can be applied to a class of similar problems. The kernel of the program is a small rule base, which is independent of the kind of cavity. To model a specific cavity, we use fuzzy logic which is implemented as a separate routine called by the rule base. We use fuzzy logic to translate from numeric to symbolic information. The example we chose for applying this kind of technique can be implemented by sequential programming. The two versions exist for comparison. However, we believe that this kind of programming can be powerf...

  19. Influence of thermal deformation in cavity mirrors on beam propagation characteristics of high-power slab lasers

    Science.gov (United States)

    Wang, Zhen; Xiao, Longsheng; Wang, Wei; Wu, Chao; Tang, Xiahui

    2018-01-01

    Owing to their good diffusion cooling and low sensitivity to misalignment, slab-shape negative-branch unstable-waveguide resonators are widely used for high-power lasers in industry. As the output beam of the resonator is astigmatic, an external beam shaping system is required. However, the transverse dimension of the cavity mirrors in the resonator is large. For a long-time operation, the heating of cavity mirrors can be non-uniform. This results in micro-deformation and a change in the radius of curvature of the cavity mirrors, and leads to an output beam of an offset optical axis of the resonator. It was found that a change in the radius of curvature of 0.1% (1 mm) caused by thermal deformation generates a transverse displacement of 1.65 mm at the spatial filter of the external beam shaping system, and an output power loss of more than 80%. This can potentially burn out the spatial filter. In order to analyze the effect of the offset optical axis of the beam on the external optical path, we analyzed the transverse displacement and rotational misalignments of the spatial filter. For instance, if the transverse displacement was 0.3 mm, the loss in the output power was 9.6% and a sidelobe appeared in the unstable direction. If the angle of rotation was 5°, the loss in the output power was 2%, and the poles were in the direction of the waveguide. Based on these results, by adjusting the bending mirror, the deviation angle of the output beam of the resonator cavity was corrected, in order to obtain maximum output power and optimal beam quality. Finally, the propagation characteristics of the corrected output beam were analyzed.

  20. Test Results of the 3.9 GHz Cavity at Fermilab

    CERN Document Server

    Solyak, N

    2004-01-01

    Fermilab is developing two types of 3.9 GHz superconducting cavities to improve performances of A0 and TTF photoinjectors. In frame of this project we have built and tested two nine-cell copper models and one 3-cell niobium accelertating cavity and series of deflecting cavities. Properties of the high order modes were carefully studied in a chain of two copper cavities at room temperature. High gradient performance were tested at helium temperature. Achieved gradients and surface resistances are exceed goal parameters. In paper we discuss results of cold tests of the 3-cell accelerating and deflecting cavities.

  1. Present status of superconducting cavity developments

    Energy Technology Data Exchange (ETDEWEB)

    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. 201 MHz Cavity R and D for MUCOOL and MICE

    International Nuclear Information System (INIS)

    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

  3. High performance MEAs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-15

    The aim of the present project is through modeling, material and process development to obtain significantly better MEA performance and to attain the technology necessary to fabricate stable catalyst materials thereby providing a viable alternative to current industry standard. This project primarily focused on the development and characterization of novel catalyst materials for the use in high temperature (HT) and low temperature (LT) proton-exchange membrane fuel cells (PEMFC). New catalysts are needed in order to improve fuel cell performance and reduce the cost of fuel cell systems. Additional tasks were the development of new, durable sealing materials to be used in PEMFC as well as the computational modeling of heat and mass transfer processes, predominantly in LT PEMFC, in order to improve fundamental understanding of the multi-phase flow issues and liquid water management in fuel cells. An improved fundamental understanding of these processes will lead to improved fuel cell performance and hence will also result in a reduced catalyst loading to achieve the same performance. The consortium have obtained significant research results and progress for new catalyst materials and substrates with promising enhanced performance and fabrication of the materials using novel methods. However, the new materials and synthesis methods explored are still in the early research and development phase. The project has contributed to improved MEA performance using less precious metal and has been demonstrated for both LT-PEM, DMFC and HT-PEM applications. New novel approach and progress of the modelling activities has been extremely satisfactory with numerous conference and journal publications along with two potential inventions concerning the catalyst layer. (LN)

  4. Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy.

    Science.gov (United States)

    Hippler, Michael; Mohr, Christian; Keen, Katherine A; McNaghten, Edward D

    2010-07-28

    Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to at least 2.5 W occurs. Absorbing gas phase species inside the cavity are detected with high sensitivity by the photoacoustic effect using a microphone embedded in the cavity. To increase sensitivity further, coupling into the cavity is modulated at a frequency corresponding to a longitudinal resonance of an organ pipe acoustic resonator (f=1.35 kHz and Q approximately 10). The technique has been characterized by measuring very weak water overtone transitions near 635 nm. Normalized noise-equivalent absorption coefficients are determined as alpha approximately 4.4x10(-9) cm(-1) s(1/2) (1 s integration time) and 2.6x10(-11) cm(-1) s(1/2) W (1 s integration time and 1 W laser power). These sensitivities compare favorably with existing state-of-the-art techniques. As an advantage, OF-CERPAS is a "zero-background" method which increases selectivity and sensitivity, and its sensitivity scales with laser power.

  5. Long term performance of the superconducting cavities of the Saclay heavy ion linac

    International Nuclear Information System (INIS)

    Cauvin, B.; Desmons, M.; Girard, J.; Letonturier, P.

    1993-12-01

    The Saclay heavy ion superconducting linac has been in operation at full energy since mid 1989. The 50 independent superconducting helix resonators have now accelerated beams for more than 20000 hours. The long term performances of the linac, and more specifically of the superconducting R.F. technology, are discussed: vibrations of the resonators, cryostat design and operation, beam time, vacuum accidents, multipactor during operation due to small leaks, stability of the electric fields, cryogenics operation. 4 figs., 6 refs

  6. Manufacturing of the L band 9-cell niobium cavity

    International Nuclear Information System (INIS)

    Matsuoka, Masanori; Ohkubo, Kohichi; Yamanaka, Toshiyuki; Kako, Eiji; Saito, Kenji; Shishido, Toshio; Ono, Masaaki; Noguchi, Shuichi.

    1993-01-01

    Since 1990, L-band niobium superconducting cavities have been developed with collaboration between our company and National Laboratory for High Energy Physics (KEK). The manufacturing procedure and the performance of 9-cell superconducting cavity are presented. The maximum accelerating gradient of 12 MV/m was attained in a cold test. (author)

  7. Formation of coronal cavities

    International Nuclear Information System (INIS)

    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

  8. Experimental Performance of the NRL 8-Beam, 4-Cavity Multiple-Beam Klystron

    Science.gov (United States)

    Abe, D. K.; Pershing, D. E.; Nguyen, K. T.; Wood, F. N.; Myers, R. E.; Eisen, E. L.; Cusick, M.; Levush, B.

    2006-01-01

    Multiple-beam amplifiers (MBAs) represent a device technology with the potential to produce high-power, efficient amplifiers with relatively wide bandwidths that are compact, low-weight, low-noise, and operate at reduced voltages relative to comparable single-beam devices. To better understand the device physics and technical issues involved in the design, fabrication, and operation of these devices, the U.S. Naval Research Laboratory (NRL) has an on-going program to develop high peak power (> 600 kW) multiple-beam klystrons (MBKs) operating in S-band (˜3.3 GHz).

  9. High Performance Proactive Digital Forensics

    International Nuclear Information System (INIS)

    Alharbi, Soltan; Traore, Issa; Moa, Belaid; Weber-Jahnke, Jens

    2012-01-01

    With the increase in the number of digital crimes and in their sophistication, High Performance Computing (HPC) is becoming a must in Digital Forensics (DF). According to the FBI annual report, the size of data processed during the 2010 fiscal year reached 3,086 TB (compared to 2,334 TB in 2009) and the number of agencies that requested Regional Computer Forensics Laboratory assistance increasing from 689 in 2009 to 722 in 2010. Since most investigation tools are both I/O and CPU bound, the next-generation DF tools are required to be distributed and offer HPC capabilities. The need for HPC is even more evident in investigating crimes on clouds or when proactive DF analysis and on-site investigation, requiring semi-real time processing, are performed. Although overcoming the performance challenge is a major goal in DF, as far as we know, there is almost no research on HPC-DF except for few papers. As such, in this work, we extend our work on the need of a proactive system and present a high performance automated proactive digital forensic system. The most expensive phase of the system, namely proactive analysis and detection, uses a parallel extension of the iterative z algorithm. It also implements new parallel information-based outlier detection algorithms to proactively and forensically handle suspicious activities. To analyse a large number of targets and events and continuously do so (to capture the dynamics of the system), we rely on a multi-resolution approach to explore the digital forensic space. Data set from the Honeynet Forensic Challenge in 2001 is used to evaluate the system from DF and HPC perspectives.

  10. Thermal performance prediction and sensitivity analysis for future deployment of molten salt cavity receiver solar power plants in Algeria

    International Nuclear Information System (INIS)

    Boudaoud, S.; Khellaf, A.; Mohammedi, K.; Behar, O.

    2015-01-01

    Highlights: • Performance of power plant with molten salt cavity receiver is assessed. • A method has been used to optimize the plant solar multiple, capacity factor and LEC. • Comparison of the simulated results to those of PS20 has shown good agreement. • Higher fossil fuel fraction reduces the LEC and increases the capacity factor. • Highland and Sahara regions are suitable for CRS plants deployment. - Abstract: Of all Concentrating Solar Power (CSP) technologies available today, the molten salt solar power plant appears to be the most important option for providing a major share of the clean and renewable electricity needed in the future. In the present paper, a technical and economic analysis for the implementation of a probable molten salt cavity receiver thermal power plant in Algeria has been carried out. In order to do so, we have investigated the effect of solar field size, storage capacity factor, solar radiation intensity, hybridization and power plant capacity on the thermal efficiency and electricity cost of the selected plant. The system advisor model has been used to perform the technical performance and the economic assessment for different locations (coastal, highland and Sahara regions) in Algeria. Taking into account various factors, a method has been applied to optimize the solar multiple and the capacity factor of the plant, to get a trade-off between the incremental investment costs of the heliostat field and the thermal energy storage. The analysis has shown that the use of higher fossil fuel fraction significantly reduces the levelized electricity cost (LEC) and sensibly increases the capacity factor (CF). The present study indicates that hybrid molten salt solar tower power technology is very promising. The CF and the LEC have been found to be respectively of the order of 71% and 0.35 $/kW e . For solar-only power plants, these parameters are respectively about 27% and 0.63 $/kW e . Therefore, hybrid central receiver systems are

  11. Cavity quantum electrodynamics

    International Nuclear Information System (INIS)

    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

  12. Hollow waveguide cavity ringdown spectroscopy

    Science.gov (United States)

    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.

  13. High gradient RF test results of S-band and C-band cavities for medical linear accelerators

    Science.gov (United States)

    Degiovanni, A.; Bonomi, R.; Garlasché, M.; Verdú-Andrés, S.; Wegner, R.; Amaldi, U.

    2018-05-01

    TERA Foundation has proposed and designed hadrontherapy facilities based on novel linacs, i.e. high gradient linacs which accelerate either protons or light ions. The overall length of the linac, and therefore its cost, is almost inversely proportional to the average accelerating gradient. With the scope of studying the limiting factors for high gradient operation and to optimize the linac design, TERA, in collaboration with the CLIC Structure Development Group, has conducted a series of high gradient experiments. The main goals were to study the high gradient behavior and to evaluate the maximum gradient reached in 3 and 5.7 GHz structures to direct the design of medical accelerators based on high gradient linacs. This paper summarizes the results of the high power tests of 3.0 and 5.7 GHz single-cell cavities.

  14. High-dose superselective intra-arterial cisplatin and concomitant radiation therapy for carcinoma of the oral cavity

    International Nuclear Information System (INIS)

    Suzuki, Gen; Tanaka, Norimitsu; Ogo, Etuyo

    2007-01-01

    The purpose of this study was to evaluate the effect of high-dose superselective intra-arterial cisplatin and concomitant radiation therapy for carcinoma of the oral cavities. The subjects consisted of 18 patients with carcinoma of the oral, and cavity treated with superselective intra-arterial infusion of high dose cisplatin (100 mg/body) concomitant with delivery of external beam radiotherapy (median total dose, 60.8 Gy) between 2001 and 2004. Sodium thiosulfate was administered intravenously to provide effective cisplatin neutlization. They were International Union Against Cancer (UICC)1997 stage II-IV (stage II: 4 patients, stage III: 4 patients, stage IV: 10 patients). Patients ranged from 43-81 years of age, with a median of 60 years, and included 14 men and 4 women. A follow-up period was 6 months minimum from the atart of the radiation therapy, the median follow up period at 28 months. The three-year overall survival rate was 71%. The three-year disease free rate and local control rate were 60% and 65%, respectively. Three-year local control rate of the T2-3 was achieved at 83%, and that for T4 at 50%. There was borderline significant difference in local control rate between T2-3 and T4 (p=0.05). We conclude that the high-dose superselective intra-arterial cisplatin and concomitant radiation therapy provides effective results in organ preservation for cancer of oral cavities. Further studies are also required to determine the validity of this method. (author)

  15. Automated Surface Classification of SRF Cavities for the Investigation of the Influence of Surface Properties onto the Operational Performance

    International Nuclear Information System (INIS)

    Wenskat, Marc

    2015-07-01

    Superconducting niobium radio-frequency cavities are fundamental for the European XFEL and the International Linear Collider. To use the operational advantages of superconducting cavities, the inner surface has to fulfill quite demanding requirements. The surface roughness and cleanliness improved over the last decades and with them, the achieved maximal accelerating field. Still, limitations of the maximal achieved accelerating field are observed, which are not explained by localized geometrical defects or impurities. The scope of this thesis is a better understanding of these limitations in defect free cavities based on global, rather than local, surface properties. For this goal, more than 30 cavities underwent subsequent surface treatments, cold RF tests and optical inspections within the ILC-HiGrade research program and the XFEL cavity production. An algorithm was developed which allows an automated surface characterization based on an optical inspection robot. This algorithm delivers a set of optical surface properties, which describes the inner cavity surface. These optical surface properties deliver a framework for a quality assurance of the fabrication procedures. Furthermore, they shows promising results for a better understanding of the observed limitations in defect free cavities.

  16. Automated Surface Classification of SRF Cavities for the Investigation of the Influence of Surface Properties onto the Operational Performance

    Energy Technology Data Exchange (ETDEWEB)

    Wenskat, Marc

    2015-07-15

    Superconducting niobium radio-frequency cavities are fundamental for the European XFEL and the International Linear Collider. To use the operational advantages of superconducting cavities, the inner surface has to fulfill quite demanding requirements. The surface roughness and cleanliness improved over the last decades and with them, the achieved maximal accelerating field. Still, limitations of the maximal achieved accelerating field are observed, which are not explained by localized geometrical defects or impurities. The scope of this thesis is a better understanding of these limitations in defect free cavities based on global, rather than local, surface properties. For this goal, more than 30 cavities underwent subsequent surface treatments, cold RF tests and optical inspections within the ILC-HiGrade research program and the XFEL cavity production. An algorithm was developed which allows an automated surface characterization based on an optical inspection robot. This algorithm delivers a set of optical surface properties, which describes the inner cavity surface. These optical surface properties deliver a framework for a quality assurance of the fabrication procedures. Furthermore, they shows promising results for a better understanding of the observed limitations in defect free cavities.

  17. High power tests of an electroforming cavity operating at 11.424 GHz

    Science.gov (United States)

    Dolgashev, V. A.; Gatti, G.; Higashi, Y.; Leonardi, O.; Lewandowski, J. R.; Marcelli, A.; Rosenzweig, J.; Spataro, B.; Tantawi, S. G.; Yeremian, D. A.

    2016-03-01

    The achievement of ultra high accelerating gradients is mandatory in order to fabricate compact accelerators at 11.424 GHz for scientific and industrial applications. An extensive experimental and theoretical program to determine a reliable ultra high gradient operation of the future linear accelerators is under way in many laboratories. In particular, systematic studies on the 11.424 GHz frequency accelerator structures, R&D on new materials and the associated microwave technology are in progress to achieve accelerating gradients well above 120 MeV/m. Among the many, the electroforming procedure is a promising approach to manufacture high performance RF devices in order to avoid the high temperature brazing and to produce precise RF structures. We report here the characterization of a hard high gradient RF accelerating structure at 11.424 GHz fabricated using the electroforming technique. Low-level RF measurements and high power RF tests carried out at the SLAC National Accelerator Laboratory on this prototype are presented and discussed. In addition, we present also a possible layout where the water-cooling of irises based on the electroforming process has been considered for the first time.

  18. Feasibility and safety of cavity-directed stereotactic radiosurgery for brain metastases at a high-volume medical center

    Directory of Open Access Journals (Sweden)

    Paul Rava, MD PhD

    2016-07-01

    Conclusions: Excellent local control is achievable with cavity-directed SRS in well-selected patients, particularly for lesions with diameter <3 cm and resection cavity volumes <14 mL. Long-term survival is possible for select patients.

  19. High performance light water reactor

    International Nuclear Information System (INIS)

    Squarer, D.; Schulenberg, T.; Struwe, D.; Oka, Y.; Bittermann, D.; Aksan, N.; Maraczy, C.; Kyrki-Rajamaeki, R.; Souyri, A.; Dumaz, P.

    2003-01-01

    The objective of the high performance light water reactor (HPLWR) project is to assess the merit and economic feasibility of a high efficiency LWR operating at thermodynamically supercritical regime. An efficiency of approximately 44% is expected. To accomplish this objective, a highly qualified team of European research institutes and industrial partners together with the University of Tokyo is assessing the major issues pertaining to a new reactor concept, under the co-sponsorship of the European Commission. The assessment has emphasized the recent advancement achieved in this area by Japan. Additionally, it accounts for advanced European reactor design requirements, recent improvements, practical design aspects, availability of plant components and the availability of high temperature materials. The final objective of this project is to reach a conclusion on the potential of the HPLWR to help sustain the nuclear option, by supplying competitively priced electricity, as well as to continue the nuclear competence in LWR technology. The following is a brief summary of the main project achievements:-A state-of-the-art review of supercritical water-cooled reactors has been performed for the HPLWR project.-Extensive studies have been performed in the last 10 years by the University of Tokyo. Therefore, a 'reference design', developed by the University of Tokyo, was selected in order to assess the available technological tools (i.e. computer codes, analyses, advanced materials, water chemistry, etc.). Design data and results of the analysis were supplied by the University of Tokyo. A benchmark problem, based on the 'reference design' was defined for neutronics calculations and several partners of the HPLWR project carried out independent analyses. The results of these analyses, which in addition help to 'calibrate' the codes, have guided the assessment of the core and the design of an improved HPLWR fuel assembly. Preliminary selection was made for the HPLWR scale

  20. A high-gain and high-efficiency X-band triaxial klystron amplifier with two-stage cascaded bunching cavities

    Science.gov (United States)

    Zhang, Wei; Ju, Jinchuan; Zhang, Jun; Zhong, Huihuang

    2017-12-01

    To achieve GW-level amplification output radiation at the X-band, a relativistic triaxial klystron amplifier with two-stage cascaded double-gap bunching cavities is investigated. The input cavity is optimized to obtain a high absorption rate of the external injection microwave. The cascaded bunching cavities are optimized to achieve a high depth of the fundamental harmonic current. A double-gap standing wave extractor is designed to improve the beam wave conversion efficiency. Two reflectors with high reflection coefficients both to the asymmetric mode and the TEM mode are employed to suppress the asymmetric mode competition and TEM mode microwave leakage. Particle-in-cell simulation results show that a high power microwave with a power of 2.53 GW and a frequency of 8.4 GHz is generated with a 690 kV, 9.3 kA electron beam excitation and a 25 kW seed microwave injection. Particularly, the achieved power conversion efficiency is about 40%, and the gain is as high as 50 dB. Meanwhile, there is insignificant self-excitation of the parasitic mode in the proposed structure by adopting the reflectors. The relative phase difference between the injected signals and the output microwaves keeps locked after the amplifier becomes saturated.

  1. Ultrasensitive, real-time trace gas detection using a high-power, multimode diode laser and cavity ringdown spectroscopy.

    Science.gov (United States)

    Karpf, Andreas; Qiao, Yuhao; Rao, Gottipaty N

    2016-06-01

    We present a simplified cavity ringdown (CRD) trace gas detection technique that is insensitive to vibration, and capable of extremely sensitive, real-time absorption measurements. A high-power, multimode Fabry-Perot (FP) diode laser with a broad wavelength range (Δλlaser∼0.6  nm) is used to excite a large number of cavity modes, thereby reducing the detector's susceptibility to vibration and making it well suited for field deployment. When detecting molecular species with broad absorption features (Δλabsorption≫Δλlaser), the laser's broad linewidth removes the need for precision wavelength stabilization. The laser's power and broad linewidth allow the use of on-axis cavity alignment, improving the signal-to-noise ratio while maintaining its vibration insensitivity. The use of an FP diode laser has the added advantages of being inexpensive, compact, and insensitive to vibration. The technique was demonstrated using a 1.1 W (λ=400  nm) diode laser to measure low concentrations of nitrogen dioxide (NO2) in zero air. A sensitivity of 38 parts in 1012 (ppt) was achieved using an integration time of 128 ms; for single-shot detection, 530 ppt sensitivity was demonstrated with a measurement time of 60 μs, which opens the door to sensitive measurements with extremely high temporal resolution; to the best of our knowledge, these are the highest speed measurements of NO2 concentration using CRD spectroscopy. The reduced susceptibility to vibration was demonstrated by introducing small vibrations into the apparatus and observing that there was no measurable effect on the sensitivity of detection.

  2. A high gradient test of a single-cell superconducting radio frequency cavity with a feedback waveguide

    Science.gov (United States)

    Kostin, Roman; Avrakhov, Pavel; Kanareykin, Alexei; Solyak, Nikolay; Yakovlev, Vyacheslav; Kazakov, Sergey; Wu, Genfa; Khabiboulline, Timergali; Rowe, Allan; Rathke, John

    2015-09-01

    The most severe problem of the international linear collider (ILC-type) is its high cost, resulting in part from the enormous length of the collider. This length is determined mainly by the achievable accelerating gradient in the RF system of the collider. In current technology, the maximum acceleration gradient in superconducting (SC) structures is determined mainly by the value of the surface RF magnetic field. In order to increase the gradient, a superconducting traveling wave accelerating (STWA) structure is suggested. Utilization of STWA structure with small phase advance per cell for future high energy linear colliders such as ILCs may provide an accelerating gradient 1.2-1.4 times larger [1] than a standing wave structure. However, STWA structure requires a feedback waveguide for power redirecting from the end of the structure back to the front end of accelerating structure. Recent tests of a 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient of a single-cell ILC-type cavity from the same manufacturer [2]. In the present paper, high gradient test results are presented.

  3. High precision slotted cavity measurement of a novel ceramic state polymer electrolyte

    Science.gov (United States)

    Quan, Wei; NurulAfsar, Mohammed

    2018-01-01

    Thin film materials are already used in a variety of microwave and higher frequency applications such as electrically tunable microwave devices, integrated circuits like MMICs, radomes, and radar absorbing coating. The determination of the dielectric properties of these films is thus of significant importance. The measurement of complex dielectric permittivity of thin films is very difficult at microwave, millimeter, and THz frequencies because both the amplitude change and phase shift are not large enough to evaluate the real part of the dielectric permittivity. A specially designed transverse slotted cavity for X-band microwave measurement has been designed and constructed to employ with a vector network analyzer to evaluate the real part of dielectric permittivity of thin films accurately and conveniently. Commercially available polymer thin films are measured to validate the methods.

  4. Green high-power tunable external-cavity GaN diode laser at 515 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam...... incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode...... laser system....

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

    Science.gov (United States)

    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.

  6. Observation of the fundamental Nyquist noise limit in an ultra-high Q-factor cryogenic bulk acoustic wave cavity

    Energy Technology Data Exchange (ETDEWEB)

    Goryachev, Maxim, E-mail: maxim.goryachev@uwa.edu.au; Ivanov, Eugene N.; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Kann, Frank van [School of Physics, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia); Galliou, Serge [Department of Time and Frequency, FEMTO-ST Institute, ENSMM, 26 Chemin de l' Épitaphe, 25000 Besançon (France)

    2014-10-13

    Thermal Nyquist noise fluctuations of high-Q bulk acoustic wave cavities have been observed at cryogenic temperatures with a DC superconducting quantum interference device amplifier. High Q modes with bandwidths of few tens of milliHz produce thermal fluctuations with a signal-to-noise ratio of up to 23 dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that the quality factor remains extremely high (Q > 10{sup 8} at low order overtones) for very weak (thermal) system motion at low temperatures, when compared to values measured with relatively strong external excitation. This result represents an enabling step towards operating such a high-Q acoustic device at the standard quantum limit.

  7. section of an accelerating cavity from LEP

    CERN Multimedia

    This is a section of an accelerating cavity from LEP, cut in half 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 are now used in LEP to double the energy of the particle beams.

  8. Pulse compression by Raman induced cavity dumping

    International Nuclear Information System (INIS)

    De Rougemont, F.; Xian, D.K.; Frey, R.; Pradere, F.

    1985-01-01

    High efficiency pulse compression using Raman induced cavity dumping has been studied theoretically and experimentally. Through stimulated Raman scattering the electromagnetic energy at a primary frequency is down-converted and extracted from a storage cavity containing the Raman medium. Energy storage may be achieved either at the laser frequency by using a laser medium inside the storage cavity, or performed at a new frequency obtained through an intracavity nonlinear process. The storage cavity may be dumped passively through stimulated Raman scattering either in an oscillator or in an amplifier. All these cases have been studied by using a ruby laser as the pump source and compressed hydrogen as the Raman scatter. Results differ slightly accordingly to the technique used, but pulse shortenings higher than 10 and quantum efficiencies higher than 80% were obtained. This method could also be used with large power lasers of any wavelength from the ultraviolet to the farinfrared spectral region

  9. radiofrequency cavity

    CERN Multimedia

    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.

  10. Development of high performance cladding

    International Nuclear Information System (INIS)

    Kiuchi, Kiyoshi

    2003-01-01

    The developments of superior next-generation light water reactor are requested on the basis of general view points, such as improvement of safety, economics, reduction of radiation waste and effective utilization of plutonium, until 2030 year in which conventional reactor plants should be renovate. Improvements of stainless steel cladding for conventional high burn-up reactor to more than 100 GWd/t, developments of manufacturing technology for reduced moderation-light water reactor (RMWR) of breeding ratio beyond 1.0 and researches of water-materials interaction on super critical pressure-water cooled reactor are carried out in Japan Atomic Energy Research Institute. Stable austenite stainless steel has been selected for fuel element cladding of advanced boiling water reactor (ABWR). The austenite stain less has the superiority for anti-irradiation properties, corrosion resistance and mechanical strength. A hard spectrum of neutron energy up above 0.1 MeV takes place in core of the reduced moderation-light water reactor, as liquid metal-fast breeding reactor (LMFBR). High performance cladding for the RMWR fuel elements is required to get anti-irradiation properties, corrosion resistance and mechanical strength also. Slow strain rate test (SSRT) of SUS 304 and SUS 316 are carried out for studying stress corrosion cracking (SCC). Irradiation tests in LMFBR are intended to obtain irradiation data for damaged quantity of the cladding materials. (M. Suetake)

  11. CEBAF: Accelerating cavities look good

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. CEBAF: Accelerating cavities look good

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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%.

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

    Energy Technology Data Exchange (ETDEWEB)

    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%.

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

    International Nuclear Information System (INIS)

    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%.

  16. Hydroforming of elliptical cavities

    Science.gov (United States)

    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

  17. Hydroforming of elliptical cavities

    Directory of Open Access Journals (Sweden)

    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

  18. Study of the mechanical stability of superconducting cavities and stiffening of these cavities by copper coating performed with thermal spray techniques; Etudes de la stabilite mecanique des cavites supraconductrices et de la methode de rigidification par projection thermique de cuivre

    Energy Technology Data Exchange (ETDEWEB)

    Gassot, H

    2001-12-01

    Today's research in nuclear physics and in particle physics needs high energy or high intensity accelerators; the use of superconducting cavities constitutes a very important technological advance for the design of such facilities, allowing high accelerating gradient with few dissipation. One of the major problems is the frequency shift under Lorentz forces: since the quality factor of the superconducting cavities is much higher than the external factor depending on the beam charge, their bandwidths are very narrow (several Hertz). Even very small mechanical deformations under Lorentz forces could induce a frequency shift which exceeds the bandwidth when the accelerating gradient becomes very high. The contribution of this thesis consists at first in a numerical analysis of this problem, then in a mechanical study of a new method for stiffening superconducting cavities: a copper coating over their external surface by thermal spray techniques. As it was a new experiment, the choice of the process and the optimization of the parameters have been carried out. An important part of this thesis has been dedicated to the systematic mechanical characterizations of the copper coatings since they are indispensable for the evaluation of the stiffening efficiency, some links between copper coating properties and thermal projection parameters have been established. The mechanical calculations are a prerequisite to obtain an effective reduction of mechanical deformations under Lorentz forces: they permit to localize the maximum deformations, to find the ideal position and the optimised shape of the stiffener. The methods implemented in this thesis allow to compare the different kinds of coating design and then to propose an interesting solution. Finally, an original approach concerning the frequency shift in pulsed mode has been developed recently, allowing to interpret some experimental observations. (author)

  19. Widely tunable single-/dual-wavelength fiber lasers with ultra-narrow linewidth and high OSNR using high quality passive subring cavity and novel tuning method.

    Science.gov (United States)

    Feng, Ting; Ding, Dongliang; Yan, Fengping; Zhao, Ziwei; Su, Hongxin; Yao, X Steve

    2016-08-22

    High stability single- and dual-wavelength compound cavity erbium-doped fiber lasers (EDFLs) with ultra-narrow linewidth, high optical signal to noise ratio (OSNR) and widely tunable range are demonstrated. Different from using traditional cascaded Type-1/Type-2 fiber rings as secondary cavities, we nest a Type-1 ring inside a Type-2 ring to form a passive subring cavity to achieve single-longitudinal-mode (SLM) lasing with ultra-narrow linewidth for the first time. We also show that the SLM lasing stability can be further improved by inserting a length of polarization maintaining fiber in the Type-2 ring. Using a uniform fiber Bragg grating (FBG) and two superimposed FBGs as mode restricting elements, respectively, we obtain a single-wavelength EDFL with a linewidth as narrow as 715 Hz and an OSNR as high as 73 dB, and a dual-wavelength EDFL with linewidths less than 1 kHz and OSNRs higher than 68 dB for both lasing wavelengths. Finally, by employing a novel self-designed strain adjustment device capable of applying both the compression and tension forces to the FBGs for wavelength tuning, we achieve the tuning range larger than 10 nm for both of the EDFLs.

  20. Researches on bake effect on RF superconducting cavities

    International Nuclear Information System (INIS)

    Hao Jiankui; Zhao Kui; Zhu Feng

    2005-01-01

    The Q-slope at high gradient affects the performance of superconducting cavity greatly. Recent researches show that low temperature (100-150) degree C heat treatment (bake) has positive effects on the performance of superconducting cavities. A lot of cavity tests are analyzed based on bake treatment. The average gradient E acc,max and E acc at Q=1 x 10 10 are increased by more than 3.5 MV/m. Q at E acc,max is increased and the Q-slope is improved. Analysis on bake temperature shows that higher bake temperature leads to higher Q value. Comparison of BCP and EP cavities shows that at least 60-80 μm EP is needed for BCP surface. More than 10-15 μm removal of the surface by BCP will degrade the performance of an EP cavity. Oxygen diffusion model is used to illustrate bake effect. (authors)

  1. Superconducting TESLA cavities

    Directory of Open Access Journals (Sweden)

    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.

  2. The dental cavities of equine cheek teeth: three-dimensional reconstructions based on high resolution micro-computed tomography

    Directory of Open Access Journals (Sweden)

    Kopke Susan

    2012-09-01

    Full Text Available Abstract Background Recent studies reported on the very complex morphology of the pulp system in equine cheek teeth. The continuous production of secondary dentine leads to distinct age-related changes of the endodontic cavity. Detailed anatomical knowledge of the dental cavities in all ages is required to explain the aetiopathology of typical equine endodontic diseases. Furthermore, data on mandibular and maxillary pulp systems is in high demand to provide a basis for the development of endodontic therapies. However, until now examination of the pulp cavity has been based on either sectioned teeth or clinical computed tomography. More precise results were expected by using micro-computed tomography with a resolution of about 0.1 mm and three-dimensional reconstructions based on previous greyscale analyses and histological verification. The aim of the present study was to describe the physiological configurations of the pulp system within a wide spectrum of tooth ages. Results Maxillary teeth: All morphological constituents of the endodontic cavity were present in teeth between 4 and 16 years: Triadan 06s displayed six pulp horns and five root canals, Triadan 07-10s five pulp horns and four root canals and Triadan 11s seven pulp horns and four to six root canals. A common pulp chamber was most frequent in teeth ≤5 years, but was found even in a tooth of 9 years. A large variety of pulp configurations was observed within 2.5 and 16 years post eruption, but most commonly a separation into mesial and distal pulp compartments was seen. Maxillary cheek teeth showed up to four separate pulp compartments but the frequency of two, three and four pulp compartments was not related to tooth age (P > 0.05. In Triadan 06s, pulp horn 6 was always connected to pulp horns 1 and 3 and root canal I. In Triadan 11s, pulp horns 7 and 8 were present in variable constitutions. Mandibular teeth: A common pulp chamber was present in teeth up to 15 years, but most

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

    Science.gov (United States)

    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.

  4. Suppression of multipacting in high power RF couplers operating with superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ostroumov, P.N., E-mail: ostroumov@frib.msu.edu [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States); Kazakov, S. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Morris, D.; Larter, T.; Plastun, A.S.; Popielarski, J.; Wei, J.; Xu, T. [Facility for Rare Isotope Beams (FRIB), Michigan State University, East Lansing, MI 48824 (United States)

    2017-06-01

    Capacitive input couplers based on a 50 Ω coaxial transmission line are frequently used to transmit RF power to superconducting (SC) resonators operating in CW mode. It is well known that coaxial transmission lines are prone to multipacting phenomenon in a wide range of RF power level and operating frequency. The Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University includes two types of quarter wave SC resonators (QWR) operating at 80.5 MHz and two types of half wave SC resonators (HWR) operating at 322 MHz. As was reported in ref. [1] a capacitive input coupler used with HWRs was experiencing strong multipacting that resulted in a long conditioning time prior the cavity testing at design levels of accelerating fields. We have developed an insert into 50 Ω coaxial transmission line that provides opportunity to bias the RF coupler antenna and protect the amplifier from the bias potential in the case of breakdown in DC isolation. Two of such devices have been built and are currently used for the off-line testing of 8 HWRs installed in the cryomodule.

  5. High precision measurements of 16O12C17O using a new type of cavity ring down spectrometer

    Science.gov (United States)

    Daëron, M.; Stoltmann, T.; Kassi, S.; Burkhart, J.; Kerstel, E.

    2016-12-01

    Laser absorption techniques for the measurement of isotopologue abundances in gases have been dripping into the geoscientific community over the past decade. In the field of carbon dioxide such instruments have mostly been restricted to measurements of the most abundant stable isotopologues. Distinct advantages of CRDS techniques are non-destructiveness and the ability to resolve isobaric isotopologues. The determination of low-abundance isotopologues is predominantly limited by the linewidth of the probing laser, laser jitter, laser drift and system stability. Here we present first measurements of 16O12C17O abundances using a new type of ultra-precise cavity ring down spectrometer. By the use of Optical Feedback Frequency Stabilization, we achieved a laser line width in the sub-kHz regime with a frequency drift of less than 20 Hz/s. A tight coupling with an ultra-stable ring down cavity combined with a frequency tuning mechanism which enables us to arbitrarily position spectral points (Burkart et al., 2013) allowed us to demonstrate a single-scan (2 minutes) precision of 40 ppm on the determination of the 16O12C17O abundance. These promising results imply that routine, direct, high-precision measurements of 17O-anomalies in CO2 using this non-destructive method are in reach. References:Burkart J, Romanini D, Kassi S; Optical feedback stabilized laser tuned by single-sideband modulation; Optical Letters 12:2062-2063 (2013)

  6. Interaction between beam control and rf feedback loops for high Q cavities an heavy beam loading. Revision A

    International Nuclear Information System (INIS)

    Mestha, L.K.; Kwan, C.M.; Yeung, K.S.

    1994-04-01

    An open-loop state space model of all the major low-level rf feedback control loops is derived. The model has control and state variables for fast-cycling machines to apply modern multivariable feedback techniques. A condition is derived to know when exactly we can cross the boundaries between time-varying and time-invariant approaches for a fast-cycling machine like the Low Energy Booster (LEB). The conditions are dependent on the Q of the cavity and the rate at which the frequency changes with time. Apart from capturing the time-variant characteristics, the errors in the magnetic field are accounted in the model to study the effects on synchronization with the Medium Energy Booster (MEB). The control model is useful to study the effects on beam control due to heavy beam loading at high intensities, voltage transients just after injection especially due to time-varying voltages, instability thresholds created by the cavity tuning feedback system, cross coupling between feedback loops with and without direct rf feedback etc. As a special case we have shown that the model agrees with the well known Pedersen model derived for the CERN PS booster. As an application of the model we undertook a detailed study of the cross coupling between the loops by considering all of them at once for varying time, Q and beam intensities. A discussion of the method to identify the coupling is shown. At the end a summary of the identified loop interactions is presented

  7. Strong Coupling Cavity QED with Gate-Defined Double Quantum Dots Enabled by a High Impedance Resonator

    Directory of Open Access Journals (Sweden)

    A. Stockklauser

    2017-03-01

    Full Text Available The strong coupling limit of cavity quantum electrodynamics (QED implies the capability of a matterlike quantum system to coherently transform an individual excitation into a single photon within a resonant structure. This not only enables essential processes required for quantum information processing but also allows for fundamental studies of matter-light interaction. In this work, we demonstrate strong coupling between the charge degree of freedom in a gate-defined GaAs double quantum dot (DQD and a frequency-tunable high impedance resonator realized using an array of superconducting quantum interference devices. In the resonant regime, we resolve the vacuum Rabi mode splitting of size 2g/2π=238  MHz at a resonator linewidth κ/2π=12  MHz and a DQD charge qubit decoherence rate of γ_{2}/2π=40  MHz extracted independently from microwave spectroscopy in the dispersive regime. Our measurements indicate a viable path towards using circuit-based cavity QED for quantum information processing in semiconductor nanostructures.

  8. High-Spatial-Resolution OH PLIF Visualization in a Cavity-Stabilized Ethylene-Air Turbulent Flame

    Science.gov (United States)

    Geipel, Clayton M.; Rockwell, Robert D.; Chelliah, Harsha K.; Cutler, Andrew D.; Spelker, Christopher A.; Hashem, Zeid; Danehy, Paul M.

    2017-01-01

    High-spatial-resolution OH planar laser-induced fluorescence was measured for a premixed ethylene-air turbulent flame in an electrically-heated Mach 2 continuous-flow facility (University of Virginia Supersonic Combustion Facility, Configuration E.) The facility comprised a Mach 2 nozzle, an isolator with flush-wall fuel injectors, a combustor with optical access, and an extender. The flame was anchored at a cavity flameholder with a backward-facing step of height 9 mm. The temperature-insensitive Q1(8) transition of OH was excited using laser light of wavelength 283.55 nm. A spatial filter was used to create a laser sheet approximately 25 microns thick based on full-width at half maximum (FWHM). Extension tubes increased the magnification of an intensified camera system, achieving in-plane resolution of 40 microns based on a 50% modulation transfer function (MTF). The facility was tested with total temperature 1200 K, total pressure 300 kPa, local fuel/air equivalence ratios of approximately 0.4, and local Mach number of approximately 0.73 in the combustor. A test case with reduced total temperature and another with reduced equivalence ratio were also tested. PLIF images were acquired along a streamwise plane bisecting the cavity flameholder, from the backward facing step to 120 mm downstream of the step. The smallest observed features in the flow had width of approximately 110 microns. Flame surface density was calculated for OH PLIF images.

  9. High-Speed Semiconductor Vertical-Cavity Surface-Emitting Lasers for Optical Data-Transmission Systems (Review)

    Science.gov (United States)

    Blokhin, S. A.; Maleev, N. A.; Bobrov, M. A.; Kuzmenkov, A. G.; Sakharov, A. V.; Ustinov, V. M.

    2018-01-01

    The main problems of providing a high-speed operation semiconductor lasers with a vertical microcavity (so-called "vertical-cavity surface-emitting lasers") under amplitude modulation and ways to solve them have been considered. The influence of the internal properties of the radiating active region and the electrical parasitic elements of the equivalent circuit of lasers are discussed. An overview of approaches that lead to an increase of the cutoff parasitic frequency, an increase of the differential gain of the active region, the possibility of the management of mode emission composition and the lifetime of photons in the optical microcavities, and reduction of the influence of thermal effects have been presented. The achieved level of modulation bandwidth of ˜30 GHz is close to the maximum achievable for the classical scheme of the direct-current modulation, which makes it necessary to use a multilevel modulation format to further increase the information capacity of optical channels constructed on the basis of vertical-cavity surface-emitting lasers.

  10. High-contrast controllable switching based on polystyrene nonlinear cavities in 2D hole-type photonic crystals

    Science.gov (United States)

    Paghousi, Roohollah; Fasihi, Kiazand

    2018-05-01

    We present a new high-contrast controllable switch, which is based on a polystyrene nonlinear cavity, and is implemented in a two dimensional (2D) hole-type photonic crystal (PC). We show that by applying a control signal, the input power can be transmitted to the output waveguide with a high contrast ratio. The operation of the proposed device is investigated through the use of coupled-mode theory (CMT) and finite-difference time-domain (FDTD) method. The contrast ratio of the proposed device varies between 18 and 23, which is higher than the corresponding value in the previous investigations. Based on the simulation results, with increasing the control power the range of operating power will be increased, while the contrast ratio will be decreased. It has been shown that in a modified structure, at the expense of the range of operating power and the contrast ratio, the control power can be decreased, considerably.

  11. Development of an S-band cavity-type beam position monitor for a high power THz free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Seon Yeong; Kim, Eun-San, E-mail: eskim1@knu.ac.kr; Hwang, Ji-Gwang; Heo, A.; Won, Jang Si [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Vinokurov, Nikolay A.; Jeong, Young UK, E-mail: yujung@kaeri.re.kr; Hee Park, Seong; Jang, Kyu-Ha [WCI Center for Quantum-Beam-based Radiation Research, Korea Atomic Energy Research Institute, 989-111 Daedeok-Daero, Yuseong-gu, Daejeon (Korea, Republic of)

    2015-01-15

    A cavity-type beam position monitor (BPM) has been developed for a compact terahertz (THz) free-electron laser (FEL) system and ultra-short pulsed electron Linac system at the Korea Atomic Energy Research Institute (KAERI). Compared with other types of BPMs, the cavity-type BPM has higher sensitivity and faster response time even at low charge levels. When electron beam passes through the cavity-type BPM, it excites the dipole mode of the cavity of which amplitude depends linearly on the beam offset from the center of the cavity. Signals from the BPM were measured as a function of the beam offset by using an oscilloscope. The microtron accelerator for the KAERI THz FEL produces the electron beam with an energy of 6.5 MeV and pulse length of 5 μs with a micropulse of 10-20 ps at the frequency of 2.801 GHz. The macropulse beam current is 40 mA. Because the microtron provides multi-bunch system, output signal would be the superposition of each single bunch. So high output signal can be obtained from superposition of each single bunch. The designed position resolution of the cavity-type BPM in multi-bunch is submicron. Our cavity-type BPM is made of aluminum and vacuum can be maintained by indium sealing without brazing process, resulting in easy modification and cost saving. The resonance frequency of the cavity-type BPM is 2.803 GHz and the cavity-type BPM dimensions are 200 × 220 mm (length × height) with a pipe diameter of 38 mm. The measured position sensitivity was 6.19 (mV/mm)/mA and the measured isolation between the X and Y axis was −39 dB. By measuring the thermal noise of system, position resolution of the cavity-type BPM was estimated to be less than 1 μm. In this article, we present the test results of the S-band cavity-type BPM and prove the feasibility of the beam position measurement with high resolution using this device.

  12. Development of an S-band cavity-type beam position monitor for a high power THz free-electron laser

    Science.gov (United States)

    Noh, Seon Yeong; Kim, Eun-San; Hwang, Ji-Gwang; Heo, A.; won Jang, Si; Vinokurov, Nikolay A.; Jeong, Young UK; Hee Park, Seong; Jang, Kyu-Ha

    2015-01-01

    A cavity-type beam position monitor (BPM) has been developed for a compact terahertz (THz) free-electron laser (FEL) system and ultra-short pulsed electron Linac system at the Korea Atomic Energy Research Institute (KAERI). Compared with other types of BPMs, the cavity-type BPM has higher sensitivity and faster response time even at low charge levels. When electron beam passes through the cavity-type BPM, it excites the dipole mode of the cavity of which amplitude depends linearly on the beam offset from the center of the cavity. Signals from the BPM were measured as a function of the beam offset by using an oscilloscope. The microtron accelerator for the KAERI THz FEL produces the electron beam with an energy of 6.5 MeV and pulse length of 5 μs with a micropulse of 10-20 ps at the frequency of 2.801 GHz. The macropulse beam current is 40 mA. Because the microtron provides multi-bunch system, output signal would be the superposition of each single bunch. So high output signal can be obtained from superposition of each single bunch. The designed position resolution of the cavity-type BPM in multi-bunch is submicron. Our cavity-type BPM is made of aluminum and vacuum can be maintained by indium sealing without brazing process, resulting in easy modification and cost saving. The resonance frequency of the cavity-type BPM is 2.803 GHz and the cavity-type BPM dimensions are 200 × 220 mm (length × height) with a pipe diameter of 38 mm. The measured position sensitivity was 6.19 (mV/mm)/mA and the measured isolation between the X and Y axis was -39 dB. By measuring the thermal noise of system, position resolution of the cavity-type BPM was estimated to be less than 1 μm. In this article, we present the test results of the S-band cavity-type BPM and prove the feasibility of the beam position measurement with high resolution using this device.

  13. Benchmarking state-of-the-art numerical simulation techniques for analyzing large photonic crystal membrane line defect cavities

    DEFF Research Database (Denmark)

    Gregersen, Niels; de Lasson, Jakob Rosenkrantz; Frandsen, Lars Hagedorn

    2018-01-01

    In this work, we perform numerical studies of two photonic crystal membrane microcavities, a short line-defect L5 cavity with relatively low quality (Q) factor and a longer L9 cavity with high Q. We compute the cavity Q factor and the resonance wavelength λ of the fundamental M1 mode in the two...

  14. Performance of a cavity-method-based algorithm for the prize-collecting Steiner tree problem on graphs

    Science.gov (United States)

    Biazzo, Indaco; Braunstein, Alfredo; Zecchina, Riccardo

    2012-08-01

    We study the behavior of an algorithm derived from the cavity method for the prize-collecting steiner tree (PCST) problem on graphs. The algorithm is based on the zero temperature limit of the cavity equations and as such is formally simple (a fixed point equation resolved by iteration) and distributed (parallelizable). We provide a detailed comparison with state-of-the-art algorithms on a wide range of existing benchmarks, networks, and random graphs. Specifically, we consider an enhanced derivative of the Goemans-Williamson heuristics and the dhea solver, a branch and cut integer linear programming based approach. The comparison shows that the cavity algorithm outperforms the two algorithms in most large instances both in running time and quality of the solution. Finally we prove a few optimality properties of the solutions provided by our algorithm, including optimality under the two postprocessing procedures defined in the Goemans-Williamson derivative and global optimality in some limit cases.

  15. SRF Cavity Fabrication and Materials

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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.

  17. A water-filled radio frequency accelerating cavity

    International Nuclear Information System (INIS)

    Faehl, R.J.; Keinigs, R.K.; Pogue, E.W.

    1998-01-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objective of this project was to study water-filled resonant cavities as a high-energy density source to drive high-current accelerator configurations. Basic considerations lead to the expectation that a dielectric-filled cavity should be able to store up to e/e o as much energy as a vacuum one with the same dimensions and thus be capable of accelerating a proportionately larger amount of charge before cavity depletion occurs. During this project, we confirmed that water-filled cavities with e/e o = 60-80 did indeed behave with the expected characteristics, in terms of resonant TM modes and cavity Q. We accomplished this result with numerical cavity eigenvalue codes; fully electromagnetic, two-dimensional, particle-in-cell codes; and, most significantly, with scaled experiments performed in water-filled aluminum cavities. The low-power experiments showed excellent agreement with the numerical results. Simulations of the high-field, high-current mode of operation indicated that charged-particle loss on the dielectric windows, which separate the cavity from the beamline, must be carefully controlled to avoid significant distortion of the axial fields

  18. High sensitivity and high Q-factor nanoslotted parallel quadrabeam photonic crystal cavity for real-time and label-free sensing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Daquan [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States); State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Kita, Shota; Wang, Cheng; Lončar, Marko [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Liang, Feng; Quan, Qimin [Rowland Institute at Harvard University, Cambridge, Massachusetts 02142 (United States); Tian, Huiping; Ji, Yuefeng [State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-08-11

    We experimentally demonstrate a label-free sensor based on nanoslotted parallel quadrabeam photonic crystal cavity (NPQC). The NPQC possesses both high sensitivity and high Q-factor. We achieved sensitivity (S) of 451 nm/refractive index unit and Q-factor >7000 in water at telecom wavelength range, featuring a sensor figure of merit >2000, an order of magnitude improvement over the previous photonic crystal sensors. In addition, we measured the streptavidin-biotin binding affinity and detected 10 ag/mL concentrated streptavidin in the phosphate buffered saline solution.

  19. TEM observations of crack tip: cavity interactions

    International Nuclear Information System (INIS)

    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

  20. Dynamics and performance of the free electron laser at Super-Aco with a harmonic RF cavity set on 500 MHz

    International Nuclear Information System (INIS)

    Nutarelli, D.

    2000-01-01

    This work is dedicated to the development of the potentialities of the free electron laser that has been installed on the storage ring Super-Aco at Orsay university. We have studied the dynamics of the electron beam inside a harmonic RF cavity set on 500 MHz. The impact of the geometric characteristics of the optical cavity on the transverse overlapping between laser radiation and the electron beam has been studied in details. An important part of the work has been the assessment of the optical characterization of the dielectric multi-layer mirrors of the cavity. For that purpose a complete system has been designed to assess the changes in optical properties of mirrors during laser operation. Another important part of this work was the study of the interaction process between laser radiation and the electron bunch leading to saturation. This interaction process has been simulated through a new model and some predictions given by this model have been successfully confronted to experimental data. The installation of the harmonic RF cavity has led to a significant increase of the laser radiation gain and the value of the mean power of the laser radiation has reached 300 mW. An interesting application of this technique is the generation of high energy gamma photons through Compton backscattering. A collimated 35 MeV-energy photon beam has been produced at Super-Aco with a rate of 5.10 6 photons per second. (A.C.)

  1. The three-dimensional particle-in-cell simulation analysis of cavity of high power subterahertz pulsed gyrotron

    International Nuclear Information System (INIS)

    Ito, Koyu; Jiang, Weihua

    2013-01-01

    High power sub-terahertz pulsed gyrotrons for Collective Thomson Scattering (CTS) diagnostics of fusion plasmas are being developed. The typical target parameters are: output power of 100-200 kW, operation frequency of 300 GHz, and pulsed length > 10 us. In order to support experimental development, numerical simulations were carried out by using Particle-In-Cell (PIC) code MAGIC. The oscillation mode of the electromagnetic radiation was selected as TE_1_5_,_2, for which the beam parameters and cavity dimensions were determined accordingly. The simulation results have showed maximum power of 144 kW at oscillation frequency of 292.80 GHz, with oscillation efficiency of 22.15%. (author)

  2. Refined hyperentanglement purification of two-photon systems for high-capacity quantum communication with cavity-assisted interaction

    Energy Technology Data Exchange (ETDEWEB)

    Du, Fang-Fang; Li, Tao; Long, Gui-Lu, E-mail: gllong@tsinghua.edu.cn

    2016-12-15

    Hyperentanglement, defined as the entanglement in multiple degrees of freedom (DOFs) of a photonic quantum system, has attracted much attention recently as it can improve the channel capacity of quantum communication largely. Here we present a refined hyperentanglement purification protocol (hyper-EPP) for two-photon systems in mixed hyperentangled states in both the spatial-mode and polarization DOFs, assisted by cavity quantum electrodynamics. By means of the spatial (polarization) quantum state transfer process, the quantum states that are discarded in the previous hyper-EPPs can be preserved. That is, the spatial (polarization) state of a four-photon system with high fidelity can be transformed into another four-photon system with low fidelity, not disturbing its polarization (spatial) state, which makes this hyper-EPP take the advantage of possessing a higher efficiency.

  3. High Performance Walls in Hot-Dry Climates

    Energy Technology Data Exchange (ETDEWEB)

    Hoeschele, Marc [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Springer, David [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Dakin, Bill [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); German, Alea [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

    2015-01-01

    High performance walls represent a high priority measure for moving the next generation of new homes to the Zero Net Energy performance level. The primary goal in improving wall thermal performance revolves around increasing the wall framing from 2x4 to 2x6, adding more cavity and exterior rigid insulation, achieving insulation installation criteria meeting ENERGY STAR's thermal bypass checklist. To support this activity, in 2013 the Pacific Gas & Electric Company initiated a project with Davis Energy Group (lead for the Building America team, Alliance for Residential Building Innovation) to solicit builder involvement in California to participate in field demonstrations of high performance wall systems. Builders were given incentives and design support in exchange for providing site access for construction observation, cost information, and builder survey feedback. Information from the project was designed to feed into the 2016 Title 24 process, but also to serve as an initial mechanism to engage builders in more high performance construction strategies. This Building America project utilized information collected in the California project.

  4. Effects of container cavity size and copper coating on field performance of container-grown longleaf pine seedlings

    Science.gov (United States)

    Shi-Jean Susana Sung; James D. Haywood; Mary A. Sword-Sayer; Kristina F. Connor; D. Andrew Scott

    2010-01-01

    Longleaf pine (Pinus palustris Mill.) seedlings were grown for 27 weeks in 3 container cavity sizes [small (S), medium (M), and large (L)], and half the containers were coated with copper (Cu). In November 2004, we planted 144 seedlings from each of 6 container treatments in each of 4 replications in central LA. All plots were burned in February 2006...

  5. High efficiency all-optical plasmonic diode based on a nonlinear side-coupled waveguide-cavity structure with broken symmetry

    Science.gov (United States)

    Liang, Hong-Qin; Liu, Bin; Hu, Jin-Feng; He, Xing-Dao

    2018-05-01

    An all-optical plasmonic diode, comprising a metal-insulator-metal waveguide coupled with a stub cavity, is proposed based on a nonlinear Fano structure. The key technique used is to break structural spatial symmetry by a simple reflector layer in the waveguide. The spatial asymmetry of the structure gives rise to the nonreciprocity of coupling efficiencies between the Fano cavity and waveguides on both sides of the reflector layer, leading to a nonreciprocal nonlinear response. Transmission properties and dynamic responses are numerically simulated and investigated by the nonlinear finite-difference time-domain method. In the proposed structure, high-efficiency nonreciprocal transmission can be achieved with a low power threshold and an ultrafast response time (subpicosecond level). A high maximum transmittance of 89.3% and an ultra-high transmission contrast ratio of 99.6% can also be obtained. The device can be flexibly adjusted for working wavebands by altering the stub cavity length.

  6. Cavity Processing and Preparation of 650 MHz Elliptical Cell Cavities for PIP-II

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, Allan [Fermilab; Chandrasekaran, Saravan Kumar [Fermilab; Grassellino, Anna [Fermilab; Melnychuk, Oleksandr [Fermilab; Merio, Margherita [Fermilab; Reid, Thomas [Argonne (main); Sergatskov, Dmitri [Fermilab

    2017-05-01

    The PIP-II project at Fermilab requires fifteen 650 MHz SRF cryomodules as part of the 800 MeV LINAC that will provide a high intensity proton beam to the Fermilab neutrino program. A total of fifty-seven high-performance SRF cavities will populate the cryomodules and will operate in both pulsed and continuous wave modes. These cavities will be processed and prepared for performance testing utilizing adapted cavity processing infrastructure already in place at Fermilab and Argonne. The processing recipes implemented for these structures will incorporate state-of-the art processing and cleaning techniques developed for 1.3 GHz SRF cavities for the ILC, XFEL, and LCLS-II projects. This paper describes the details of the processing recipes and associated chemistry, heat treatment, and cleanroom processes at the Fermilab and Argonne cavity processing facilities. This paper also presents single and multi-cell cavity test results with quality factors above 5·10¹⁰ and accelerating gradients above 30 MV/m.

  7. Learning Apache Solr high performance

    CERN Document Server

    Mohan, Surendra

    2014-01-01

    This book is an easy-to-follow guide, full of hands-on, real-world examples. Each topic is explained and demonstrated in a specific and user-friendly flow, from search optimization using Solr to Deployment of Zookeeper applications. This book is ideal for Apache Solr developers and want to learn different techniques to optimize Solr performance with utmost efficiency, along with effectively troubleshooting the problems that usually occur while trying to boost performance. Familiarity with search servers and database querying is expected.

  8. High-performance composite chocolate

    Science.gov (United States)

    Dean, Julian; Thomson, Katrin; Hollands, Lisa; Bates, Joanna; Carter, Melvyn; Freeman, Colin; Kapranos, Plato; Goodall, Russell

    2013-07-01

    The performance of any engineering component depends on and is limited by the properties of the material from which it is fabricated. It is crucial for engineering students to understand these material properties, interpret them and select the right material for the right application. In this paper we present a new method to engage students with the material selection process. In a competition-based practical, first-year undergraduate students design, cost and cast composite chocolate samples to maximize a particular performance criterion. The same activity could be adapted for any level of education to introduce the subject of materials properties and their effects on the material chosen for specific applications.

  9. High-Performance Composite Chocolate

    Science.gov (United States)

    Dean, Julian; Thomson, Katrin; Hollands, Lisa; Bates, Joanna; Carter, Melvyn; Freeman, Colin; Kapranos, Plato; Goodall, Russell

    2013-01-01

    The performance of any engineering component depends on and is limited by the properties of the material from which it is fabricated. It is crucial for engineering students to understand these material properties, interpret them and select the right material for the right application. In this paper we present a new method to engage students with…

  10. Toward High-Performance Organizations.

    Science.gov (United States)

    Lawler, Edward E., III

    2002-01-01

    Reviews management changes that companies have made over time in adopting or adapting four approaches to organizational performance: employee involvement, total quality management, re-engineering, and knowledge management. Considers future possibilities and defines a new view of what constitutes effective organizational design in management.…

  11. Performance of a high efficiency high power UHF klystron

    International Nuclear Information System (INIS)

    Konrad, G.T.

    1977-03-01

    A 500 kW c-w klystron was designed for the PEP storage ring at SLAC. The tube operates at 353.2 MHz, 62 kV, a microperveance of 0.75, and a gain of approximately 50 dB. Stable operation is required for a VSWR as high as 2 : 1 at any phase angle. The design efficiency is 70%. To obtain this value of efficiency, a second harmonic cavity is used in order to produce a very tightly bunched beam in the output gap. At the present time it is planned to install 12 such klystrons in PEP. A tube with a reduced size collector was operated at 4% duty at 500 kW. An efficiency of 63% was observed. The same tube was operated up to 200 kW c-w for PEP accelerator cavity tests. A full-scale c-w tube reached 500 kW at 65 kV with an efficiency of 55%. In addition to power and phase measurements into a matched load, some data at various load mismatches are presented

  12. Functional High Performance Financial IT

    DEFF Research Database (Denmark)

    Berthold, Jost; Filinski, Andrzej; Henglein, Fritz

    2011-01-01

    at the University of Copenhagen that attacks this triple challenge of increased performance, transparency and productivity in the financial sector by a novel integration of financial mathematics, domain-specific language technology, parallel functional programming, and emerging massively parallel hardware. HIPERFIT......The world of finance faces the computational performance challenge of massively expanding data volumes, extreme response time requirements, and compute-intensive complex (risk) analyses. Simultaneously, new international regulatory rules require considerably more transparency and external...... auditability of financial institutions, including their software systems. To top it off, increased product variety and customisation necessitates shorter software development cycles and higher development productivity. In this paper, we report about HIPERFIT, a recently etablished strategic research center...

  13. High performance Mo adsorbent PZC

    Energy Technology Data Exchange (ETDEWEB)

    Anon,

    1998-10-01

    We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

  14. Indoor Air Quality in High Performance Schools

    Science.gov (United States)

    High performance schools are facilities that improve the learning environment while saving energy, resources, and money. The key is understanding the lifetime value of high performance schools and effectively managing priorities, time, and budget.

  15. High performance inertial fusion targets

    International Nuclear Information System (INIS)

    Nuckolls, J.H.; Bangerter, R.O.; Lindl, J.D.; Mead, W.C.; Pan, Y.L.

    1977-01-01

    Inertial confinement fusion (ICF) designs are considered which may have very high gains (approximately 1000) and low power requirements (<100 TW) for input energies of approximately one megajoule. These include targets having very low density shells, ultra thin shells, central ignitors, magnetic insulation, and non-ablative acceleration

  16. High performance inertial fusion targets

    International Nuclear Information System (INIS)

    Nuckolls, J.H.; Bangerter, R.O.; Lindl, J.D.; Mead, W.C.; Pan, Y.L.

    1978-01-01

    Inertial confinement fusion (ICF) target designs are considered which may have very high gains (approximately 1000) and low power requirements (< 100 TW) for input energies of approximately one megajoule. These include targets having very low density shells, ultra thin shells, central ignitors, magnetic insulation, and non-ablative acceleration

  17. High performance nuclear fuel element

    International Nuclear Information System (INIS)

    Mordarski, W.J.; Zegler, S.T.

    1980-01-01

    A fuel-pellet composition is disclosed for use in fast breeder reactors. Uranium carbide particles are mixed with a powder of uraniumplutonium carbides having a stable microstructure. The resulting mixture is formed into fuel pellets. The pellets thus produced exhibit a relatively low propensity to swell while maintaining a high density

  18. PEP-II RF cavity revisited

    International Nuclear Information System (INIS)

    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

  19. High Performance JavaScript

    CERN Document Server

    Zakas, Nicholas

    2010-01-01

    If you're like most developers, you rely heavily on JavaScript to build interactive and quick-responding web applications. The problem is that all of those lines of JavaScript code can slow down your apps. This book reveals techniques and strategies to help you eliminate performance bottlenecks during development. You'll learn how to improve execution time, downloading, interaction with the DOM, page life cycle, and more. Yahoo! frontend engineer Nicholas C. Zakas and five other JavaScript experts -- Ross Harmes, Julien Lecomte, Steven Levithan, Stoyan Stefanov, and Matt Sweeney -- demonstra

  20. Baking effect on Niobium superconducting RF cavities and its physical interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Saito, K. [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan); Kneisel, P. [Thomas Jefferson Accelerator Facility, VA, (United States)

    2000-07-01

    Recently a very surprising phenomenon has been discovered at JLab and Saclay with chemically polished niobium cavities, which the baking during vacuum evacuation has benefits to improve the cavity performance: high Q and high gradient. We have confirmed the same effect on the electropolished niobium cavities. We have analyzed the temperature dependence of the surface resistance in order to understand this effect in the frame or BCS theory. In this paper these results will be presented. (author)

  1. Results of Cavity Series Fabrication at Jefferson Laboratory for the Cryomodule 'R100'

    International Nuclear Information System (INIS)

    Marhauser, F.; Clemens, W.A.; Drury, M.A.; Forehand, D.; Henry, J.; Manning, S.; Overton, R.B.; Williams, R.S.

    2011-01-01

    A series production of eight superconducting RF cavities for the cryomodule R100 was conducted at JLab in 2010. The cavities underwent chemical post-processing prior to vertical high power testing and routinely exceeded the envisaged performance specifications. After cryomodule assembly, cavities were successfully high power acceptance tested. In this paper, we present the achievements paving the way for the first demonstration of 100 MV (and beyond) in a single cryomodule to be operated at CEBAF.

  2. Carpet Aids Learning in High Performance Schools

    Science.gov (United States)

    Hurd, Frank

    2009-01-01

    The Healthy and High Performance Schools Act of 2002 has set specific federal guidelines for school design, and developed a federal/state partnership program to assist local districts in their school planning. According to the Collaborative for High Performance Schools (CHPS), high-performance schools are, among other things, healthy, comfortable,…

  3. RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. X-ray imaging of superconducting radio frequency cavities

    Science.gov (United States)

    Musser, Susan Elizabeth

    The goal of this research was to develop an improved diagnostic technique to identify the location of defects that limit superconducting radio frequency (SRF) cavity performance during cavity testing or in existing accelerators. SRF cavities are primarily constructed of niobium. Electrons within the metal of a cavity under high electric field gradient have a probability of tunneling through the potential barrier. i e. leave the surface or are field emitted in regions where defects are encountered. Field emitted electrons are accelerated in the electric fields within the cavity. The electrons can have complicated trajectories and strike the cavity walls thus producing x-rays via Coulomb interactions and/or bremsstrahlung radiation. The endpoint energy of an x-ray spectrum predicts the electron maximum final kinetic energy within the cavity. Field emission simulations can then predict the source of the field-emitted electrons and the defect(s). In a multicell cavity the cells are coupled together and act as a set of coupled oscillators. There are multiple passbands of excitation for a multicell structure operating in a particular mode. For different passbands of operation the direction and amplitude of the fields within a cavity change from that of the normal accelerating mode. Field emitted electrons have different trajectories depending on the mode and thus produce x-rays in different locations. Using a collimated sodium iodide detector and subjecting a cavity to multiple passband modes at high electric field gradient the source of a cavity's x-rays can be determined. Knowing the location of the x-rays and the maximum electron kinetic energy; field emission simulations for different passband modes can be used to determine and verify the source of the field emitted electrons from mode to mode. Once identified, the defect(s) can be repaired or modifications made to the manufacturing process.

  5. Comparative thermal performance of static sunshade and brick cavity wall for energy efficient building envelope in composite climate

    Directory of Open Access Journals (Sweden)

    Charde Meghana

    2014-01-01

    Full Text Available Energy efficient building technologies can reduce energy consumption in buildings. In present paper effect of designed static sunshade, brick cavity wall with brick projections and their combined effect on indoor air temperature has been analyzed by constructing three test rooms each of habitable dimensions (3.0 m × 4.0 m × 3.0 m and studying hourly temperatures on typical days for one month in summer and winter each. The three rooms have also been simulated using a software and the results have been compared with the experimental results. Designed static sunshade increased indoor air temperature in winter while proposed brick cavity wall with brick projections lowered it in summer. Combined effect of building elements lowered indoor air temperature in summer and increased it in winter as compared to outdoor air temperature. It is thus useful for energy conservation in buildings in composite climate.

  6. High-power comparison among brazed, clamped and electroformed X-band cavities

    Energy Technology Data Exchange (ETDEWEB)

    Spataro, B., E-mail: bruno.spataro@lnf.infn.it [INFN-LNF, Via E. Fermi 40, 00044 Frascati, Rome (Italy); Alesini, D.; Chimenti, V. [INFN-LNF, Via E. Fermi 40, 00044 Frascati, Rome (Italy); Dolgashev, V. [SLAC, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Higashi, Y. [KEK 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Migliorati, M.; Mostacci, A. [University of Rome Sapienza, Department of Fundamental and Applied Science for Engineering, Via A. Scarpa 14, 00185 Rome (Italy); Parodi, R. [INFN-Genova, Via Dodecaneso 33, 16146 Genova (Italy); Tantawi, S.G.; Yeremian, A.D. [SLAC, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2011-11-21

    We report the building procedure of X-band copper structures using the electroforming and electroplating techniques. These techniques allow the deposition of copper layers on a suitable die and they can be used to build RF structures avoiding the high temperature brazing step in the standard technique. We show the constructed prototypes and low power RF measurements and discuss the results of the high power tests at SLAC National Accelerator Laboratory.

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

    International Nuclear Information System (INIS)

    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.

  8. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    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)

  9. High performance electromagnetic simulation tools

    Science.gov (United States)

    Gedney, Stephen D.; Whites, Keith W.

    1994-10-01

    Army Research Office Grant #DAAH04-93-G-0453 has supported the purchase of 24 additional compute nodes that were installed in the Intel iPsC/860 hypercube at the Univesity Of Kentucky (UK), rendering a 32-node multiprocessor. This facility has allowed the investigators to explore and extend the boundaries of electromagnetic simulation for important areas of defense concerns including microwave monolithic integrated circuit (MMIC) design/analysis and electromagnetic materials research and development. The iPSC/860 has also provided an ideal platform for MMIC circuit simulations. A number of parallel methods based on direct time-domain solutions of Maxwell's equations have been developed on the iPSC/860, including a parallel finite-difference time-domain (FDTD) algorithm, and a parallel planar generalized Yee-algorithm (PGY). The iPSC/860 has also provided an ideal platform on which to develop a 'virtual laboratory' to numerically analyze, scientifically study and develop new types of materials with beneficial electromagnetic properties. These materials simulations are capable of assembling hundreds of microscopic inclusions from which an electromagnetic full-wave solution will be obtained in toto. This powerful simulation tool has enabled research of the full-wave analysis of complex multicomponent MMIC devices and the electromagnetic properties of many types of materials to be performed numerically rather than strictly in the laboratory.

  10. High-Performance Data Converters

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    -resolution internal D/A converters are required. Unit-element mismatch-shaping D/A converters are analyzed, and the concept of mismatch-shaping is generalized to include scaled-element D/A converters. Several types of scaled-element mismatch-shaping D/A converters are proposed. Simulations show that, when implemented...... in a standard CMOS technology, they can be designed to yield 100 dB performance at 10 times oversampling. The proposed scaled-element mismatch-shaping D/A converters are well suited for use as the feedback stage in oversampled delta-sigma quantizers. It is, however, not easy to make full use of their potential......-order difference of the output signal from the loop filter's first integrator stage. This technique avoids the need for accurate matching of analog and digital filters that characterizes the MASH topology, and it preserves the signal-band suppression of quantization errors. Simulations show that quantizers...

  11. High Precision Continuous and Real-Time Measurement of Atmospheric Oxygen Using Cavity Ring-Down Spectroscopy.

    Science.gov (United States)

    Kim-Hak, D.; Hoffnagle, J.; Rella, C.; Sun, M.

    2016-12-01

    Oxygen is a major and vital component of the Earth atmosphere representing about 21% of its composition. It is consumed or produced through biochemical processes such as combustion, respiration, and photosynthesis. Although atmospheric oxygen is not a greenhouse gas, it can be used as a top-down constraint on the carbon cycle. The variation observations of oxygen in the atmosphere are very small, in the order of the few ppm's. This presents the main technical challenge for measurement as a very high level of precision is required and only few methods including mass spectrometry, fuel cell, and paramagnetic are capable of overcoming it. Here we present new developments of a high-precision gas analyzer that utilizes the technique of Cavity Ring-Down Spectroscopy to measure oxygen concentration and oxygen isotope. Its compact and ruggedness design combined with high precision and long-term stability allows the user to deploy the instrument in the field for continuous monitoring of atmospheric oxygen level. Measurements have a 1-σ 5-minute averaging precision of 1-2 ppm for O2 over a dynamic range of 0-20%. We will present supplemental data acquired from our 10m tower measurements in Santa Clara, CA.

  12. High performance soft magnetic materials

    CERN Document Server

    2017-01-01

    This book provides comprehensive coverage of the current state-of-the-art in soft magnetic materials and related applications, with particular focus on amorphous and nanocrystalline magnetic wires and ribbons and sensor applications. Expert chapters cover preparation, processing, tuning of magnetic properties, modeling, and applications. Cost-effective soft magnetic materials are required in a range of industrial sectors, such as magnetic sensors and actuators, microelectronics, cell phones, security, automobiles, medicine, health monitoring, aerospace, informatics, and electrical engineering. This book presents both fundamentals and applications to enable academic and industry researchers to pursue further developments of these key materials. This highly interdisciplinary volume represents essential reading for researchers in materials science, magnetism, electrodynamics, and modeling who are interested in working with soft magnets. Covers magnetic microwires, sensor applications, amorphous and nanocrystalli...

  13. High performance polyethylene nanocomposite fibers

    Directory of Open Access Journals (Sweden)

    A. Dorigato

    2012-12-01

    Full Text Available A high density polyethylene (HDPE matrix was melt compounded with 2 vol% of dimethyldichlorosilane treated fumed silica nanoparticles. Nanocomposite fibers were prepared by melt spinning through a co-rotating twin screw extruder and drawing at 125°C in air. Thermo-mechanical and morphological properties of the resulting fibers were then investigated. The introduction of nanosilica improved the drawability of the fibers, allowing the achievement of higher draw ratios with respect to the neat matrix. The elastic modulus and creep stability of the fibers were remarkably improved upon nanofiller addition, with a retention of the pristine tensile properties at break. Transmission electronic microscope (TEM images evidenced that the original morphology of the silica aggregates was disrupted by the applied drawing.

  14. Multimode fiber tip Fabry-Perot cavity for highly sensitive pressure measurement.

    Science.gov (United States)

    Chen, W P; Wang, D N; Xu, Ben; Zhao, C L; Chen, H F

    2017-03-23

    We demonstrate an optical Fabry-Perot interferometer fiber tip sensor based on an etched end of multimode fiber filled with ultraviolet adhesive. The fiber device is miniature (with diameter of less than 60 μm), robust and low cost, in a convenient reflection mode of operation, and has a very high gas pressure sensitivity of -40.94 nm/MPa, a large temperature sensitivity of 213 pm/°C within the range from 55 to 85 °C, and a relatively low temperature cross-sensitivity of 5.2 kPa/°C. This device has a high potential in monitoring environment of high pressure.

  15. Nitrogen and argon doping of niobium for superconducting radio frequency cavities: a pathway to highly efficient accelerating structures

    Science.gov (United States)

    Grassellino, A.; Romanenko, A.; Sergatskov, D.; Melnychuk, O.; Trenikhina, Y.; Crawford, A.; Rowe, A.; Wong, M.; Khabiboulline, T.; Barkov, F.

    2013-10-01

    We report a surface treatment that systematically improves the quality factor of niobium radio frequency cavities beyond the expected limit for niobium. A combination of annealing in a partial pressure of nitrogen or argon gas and subsequent electropolishing of the niobium cavity surface leads to unprecedented low values of the microwave surface resistance, and an improvement in the efficiency of the accelerating structures up to a factor of 3, reducing the cryogenic load of superconducting cavities for both pulsed and continuous duty cycles. The field dependence of the surface resistance is reversed compared to standardly treated niobium.

  16. Instrumentation for localized superconducting cavity diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Conway, Z. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Physics Division; Ge, M. [Cornell Lab. for Accelerator-Based Sciences and Education, Ithaca, NY (United States); Iwashita, Y. [Kyoto Univ. (Japan)

    2017-01-12

    Superconducting accelerator cavities are now routinely operated at levels approaching the theoretical limit of niobium. To achieve these operating levels more information than is available from the RF excitation signal is required to characterize and determine fixes for the sources of performance limitations. This information is obtained using diagnostic techniques which complement the analysis of the RF signal. In this paper we describe the operation and select results from three of these diagnostic techniques: the use of large scale thermometer arrays, second sound wave defect location and high precision cavity imaging with the Kyoto camera.

  17. HIGH-PERFORMANCE COATING MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.

    2007-01-01

    Corrosion, erosion, oxidation, and fouling by scale deposits impose critical issues in selecting the metal components used at geothermal power plants operating at brine temperatures up to 300 C. Replacing these components is very costly and time consuming. Currently, components made of titanium alloy and stainless steel commonly are employed for dealing with these problems. However, another major consideration in using these metals is not only that they are considerably more expensive than carbon steel, but also the susceptibility of corrosion-preventing passive oxide layers that develop on their outermost surface sites to reactions with brine-induced scales, such as silicate, silica, and calcite. Such reactions lead to the formation of strong interfacial bonds between the scales and oxide layers, causing the accumulation of multiple layers of scales, and the impairment of the plant component's function and efficacy; furthermore, a substantial amount of time is entailed in removing them. This cleaning operation essential for reusing the components is one of the factors causing the increase in the plant's maintenance costs. If inexpensive carbon steel components could be coated and lined with cost-effective high-hydrothermal temperature stable, anti-corrosion, -oxidation, and -fouling materials, this would improve the power plant's economic factors by engendering a considerable reduction in capital investment, and a decrease in the costs of operations and maintenance through optimized maintenance schedules.

  18. 980 nm high brightness external cavity broad area diode laser bar

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

    2009-01-01

    We demonstrate of-axis spectral beam combining applied to a 980 nm high power broad area diode laser bar. The experiments yielded 9 W of optical power at 30 A of operating current and the measured M2 values of the combined beam from 12 emitters were 1.9 and 6.4 for the fast and the slow axis......, respectively. The slow axis beam quality was 5-6 times better than the value obtained from a single emitter in free running mode. A high brightness of 79 MW/cm2-str was achieved using this configuration. To our knowledge, this is the highest brightness level ever achieved from a broad area diode laser bar....

  19. A Many-Atom Cavity QED System with Homogeneous Atom-Cavity Coupling

    OpenAIRE

    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.

  20. A high stability wavelength-tunable narrow-linewidth and single-polarization erbium-doped fiber laser using a compound-cavity structure

    International Nuclear Information System (INIS)

    Feng, Ting; Yan, Fengping; Peng, Wanjing; Liu, Shuo; Tan, Siyu; Liang, Xiao; Wen, Xiaodong

    2014-01-01

    A high stability wavelength-tunable narrow-linewidth and single-polarization erbium-doped fiber laser using a compound-cavity structure is proposed and demonstrated experimentally. The compound-cavity is composed of a main-linear-cavity and a subring-cavity. Using a pump power of 150 mW, the optical signal to noise ratio of the laser output is as high as ∼67 dB; the wavelength and output power fluctuation are 0.7 pm and 0.07 dBm respectively in an experimental period of 1 h; the linewidth of the laser output is as narrow as 650 Hz; the degree of polarization of the laser output is stable at a value of 100.8% in 15 min and the polarization extinction ratio is as high as 30.57 dB; the wavelength-tunable range is as wide as ∼8.1 nm. The proposed fiber laser can be used in areas where high stability, narrow-linewidth, single-polarization and wide wavelength-tunable range are needed. (letter)

  1. High-accuracy continuous airborne measurements of greenhouse gases (CO2 and CH4) using the cavity ring-down spectroscopy (CRDS) technique

    NARCIS (Netherlands)

    Chen, H.; Winderlich, J.; Gerbig, C.; Hoefer, A.; Rella, C. W.; Crosson, E. R.; Van Pelt, A. D.; Steinbach, J.; Kolle, O.; Beck, V.; Daube, B. C.; Gottlieb, E. W.; Chow, V. Y.; Santoni, G. W.; Wofsy, S. C.

    2010-01-01

    High-accuracy continuous measurements of greenhouse gases (CO2 and CH4) during the BARCA (Balancao Atmosferico Regional de Carbono na Amazonia) phase B campaign in Brazil in May 2009 were accomplished using a newly available analyzer based on the cavity ring-down spectroscopy (CRDS) technique. This

  2. Delivering high performance BWR fuel reliably

    International Nuclear Information System (INIS)

    Schardt, J.F.

    1998-01-01

    Utilities are under intense pressure to reduce their production costs in order to compete in the increasingly deregulated marketplace. They need fuel, which can deliver high performance to meet demanding operating strategies. GE's latest BWR fuel design, GE14, provides that high performance capability. GE's product introduction process assures that this performance will be delivered reliably, with little risk to the utility. (author)

  3. High-Gradient Test of a 3 GHz Single-Cell Cavity

    CERN Document Server

    Verdú-Andrés, S; Bonomi, R; Degiovanni, A; Garlasché, M; Garonna, A; Mellace, C; Pearce, P; S. Verdú-Andrés; Wegner, R

    2010-01-01

    Pro­ton and car­bon ion beams pre­sent ad­van­ta­geous depth-dose dis­tri­bu­tions with re­spect to X-rays. Car­bon ions allow a bet­ter con­trol of "ra­diore­sis­tant" tu­mours due to their high­er bi­o­log­i­cal re­sponse. For deep-seat­ed tu­mours pro­ton and car­bon ion beams of some nA and en­er­gies of about 200 MeV and 400 MeV/u re­spec­tive­ly are need­ed. For these ap­pli­ca­tions TERA pro­posed the "cy­clinac": a high-fre­quen­cy linac which boosts the hadrons ac­cel­er­at­ed by a cy­clotron. The di­men­sions of the com­plex can be re­duced if high­er ac­cel­er­at­ing gra­di­ents are achieved in the linac. To test the max­i­mum achiev­able fields, a 3 GHz cav­i­ty has been built by TERA. The 19 mm-long cell is fore­seen to be ex­cit­ed at 200 Hz by 3 us RF puls­es and should reach a 40 MV/m ac­cel­er­at­ing gra­di­ent, which cor­re­sponds to a peak sur­face elec­tric field Es of 260 MV/m. In a first high-pow­er test per­for...

  4. Dynamics of a green high-power tunable external-cavity broad-area GaN diode laser

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Hansen, Anders Kragh

    2018-01-01

    system based on a GaN BAL and Littrow external-cavity is investigated experimentally. The regular pulse package oscillation (PPO) is observed just above the threshold. The oscillating period of the pulse package decreases with the increasing injected current. As the current increases further, the pulse...... package oscillates irregularly, and finally changes to a chaotic state. The PPO is observed, for the first time to our knowledge, in a BAL with an external-cavity grating feedback....

  5. High-resolution Measurements of Gas-Phase Hydrogen Chloride (HCl) in the Atmosphere by Cavity Ring Down Spectroscopy

    Science.gov (United States)

    Hoffnagle, John; Chen, Hongbing; Lee, Jim; Rella, Chris; Kim-Hak, David; Winkler, Renato; Markovic, Milos; Veres, Patrick

    2017-04-01

    Halogen radical species, such as chlorine and bromine atoms and their oxides, can greatly affect the chemical composition of the troposphere. Hydrogen chloride is the dominant (gas-phase) contributor to the tropospheric chlorine inventory. Real time in situ observations of HCl can provide an important window into the complex photochemical reaction pathways for chlorine in the atmosphere, including heterogeneous reactions on aerosol surfaces. In this work, we report a novel, commercially-available HCl gas-phase analyzer (G2108, Picarro Inc. Santa Clara, CA, USA) based upon Cavity Ring Down Spectroscopy (CRDS) in the near-infrared, and discuss its performance. With a measurement interval of approximately 2 seconds, a precision of better than 40 parts-per-trillion (1 sigma, 30 seconds), and a response time of approximately 1-2 minutes (10 - 90% rise time or 90 - 10% fall time), this analyzer is well-suited for measurements of atmospherically-relevant concentrations of HCl, in both laboratory and field. CRDS provides very stable measurements and low drift, requiring infrequent calibration of the instrument, and can therefore be operated remotely for extended periods of time. In this work we also present results from a laboratory intercomparison of the Picarro G2108 analyzer and an iodide ion time-of-flight Chemical Ionization Mass Spectrometer (CIMS), and the results of the analyzer time response tests.

  6. Temporal features of the outflow of heavy ionospheric ions in response to a high altitude plasma cavity

    International Nuclear Information System (INIS)

    Singh, Nagendra; Hwang, K.S.; Torr, D.G.; Richards, P.

    1989-01-01

    Using a hydrodynamic model for the plasma, it is demonstrated that the auroral plasma cavity is capable of drawing an appreciably large flux of oxygen ions, which are normally gravitationally bound. This escape mechanism of O + does not involve any additional heating or acceleration of the plasma in the ionosphere. The temporal evolution of the outflow shows that it starts near the cavity and penetrates into the ionosphere with a flux front moving down with the ion-acoustic speed. A steady outflow is reached in a few hours for a cavity at a height of one R e if the cavity is maintained. This time reduces to + (Γ o + ) increases; for the lower edge of the cavity in the altitude range 3-10 x 10 3 km, the steady flux is found to be in the range 10 9 > Γ o + (cm -3 s -1 ) > 10 7 . An analysis for the steady state shows that outflow is controlled by the density scale height in the cavity

  7. GaN-based vertical-cavity laser performance improvements using tunnel-junction-cascaded active regions

    International Nuclear Information System (INIS)

    Piprek, Joachim

    2014-01-01

    This Letter investigates the output power enhancement achieved by tunnel junction insertion into the InGaN multi-quantum well (MQW) active region of a 410 nm vertical-cavity surface-emitting laser which enables the repeated use of carriers for light generation (carrier recycling). While the number of quantum wells remains unchanged, the tunnel junction eliminates absorption caused by the non-uniform MQW carrier distribution. The thermal resistance drops and the excess bias lead to a surprisingly small rise in self-heating.

  8. Video Toroid Cavity Imager

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Influences of thermal deformation of cavity mirrors induced by high energy DF laser to beam quality under the simulated real physical circumstances

    Science.gov (United States)

    Deng, Shaoyong; Zhang, Shiqiang; He, Minbo; Zhang, Zheng; Guan, Xiaowei

    2017-05-01

    The positive-branch confocal unstable resonator with inhomogeneous gain medium was studied for the normal used high energy DF laser system. The fast changing process of the resonator's eigenmodes was coupled with the slow changing process of the thermal deformation of cavity mirrors. Influences of the thermal deformation of cavity mirrors to the outcoupled beam quality and transmission loss of high frequency components of high energy laser were computed. The simulations are done through programs compiled by MATLAB and GLAD software and the method of combination of finite elements and Fox-li iteration algorithm was used. Effects of thermal distortion, misaligned of cavity mirrors and inhomogeneous distribution of gain medium were introduced to simulate the real physical circumstances of laser cavity. The wavefront distribution and beam quality (including RMS of wavefront, power in the bucket, Strehl ratio, diffraction limit β, position of the beam spot center, spot size and intensity distribution in far-field ) of the distorted outcoupled beam were studied. The conclusions of the simulation agree with the experimental results. This work would supply references of wavefront correction range to the adaptive optics system of interior alleyway.

  10. Circuit QED with 3D cavities

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Edwar; Eder, Peter; Fischer, Michael; Goetz, Jan; Deppe, Frank; Gross, Rudolf [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, TU Muenchen, 85748 Garching (Germany); Nanosystems Initiative Munich (NIM), 80799 Muenchen (Germany); Haeberlein, Max; Wulschner, Karl Friedrich [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany); Physik-Department, TU Muenchen, 85748 Garching (Germany); Fedorov, Kirill; Marx, Achim [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching (Germany)

    2016-07-01

    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 studies on transmon qubits capacitively coupled to 3D cavities. The internal quality factors of our 3D cavities, machined out of high purity aluminum, are above 1.4 .10{sup 6} at the single photon level and a temperature of 50 mK. For characterization of the sample, we perform dispersive shift measurements up to the third energy level of the qubit. We show simulations and data describing the effect of the transmon geometry on it's capacitive properties. In addition, we present progress towards an integrated quantum memory application.

  11. Practice of superselective intraarterial high-dose cisplatin chemoradiotherapy in the oral cavity

    International Nuclear Information System (INIS)

    Yoshida, Tomoyuki; Nakamura, Kazuhiro; Tsukahara, Kiyoaki; Inagaki, Taro; Ito, Hiroyuki; Shimizu, Akira; Takata, Daisuke; Okamoto, Isaku; Kondo, Takahito

    2011-01-01

    Superselective intraarterial infusion enables high-dose chemotherapeutic agents to be administered via tumor feeding vessels to neutralize and limit the adverse cisplatin effects acceptable. Between 1998 and 2008, we evaluated the efficacy of first-line therapy and adverse events in 30 subjects with oral squamous cell cancer undergoing simultaneous superselective intra arterial high-dose chemotherapy and radiotherapy. The 30 subjects- 23 men and 7 women aged 40 to 72- consisted of 3 T2, 12 T3, and 15 T4. Four patients had N0, 8 N1, 7 N2b, 8 N2c, and 3 N3 disease. Two were in CS II, 6 III, 17 IVa, and 5 IVb (III>93%, IV: 73%). Superselective intra arterial chemotherapy delivered through the femoral artery used the Seldinger technique. A single cisplatin dose of 100-550 mg/m 2 (mean 440 mg/m 2 ). Five minutes after intra arterial infusion, sodium thiosulphate (9 g/m 2 ) was administered via a peripheral cutaneous vein in the contralateral forearm. Concurrent radiotherapy started on Day 2 at 2 Gy per session for a total of 60 Gy. Two to 3 weeks later, 15 under went the second course of superselective intra arterial chemotherapy after tumor feeding vessels were visualized angiographically. Four (13.3%) subjects with Grade 3 or greater myelosuppression required granulocyte-colony stimulating factor (G-CSF). Grade 3 or greater mucositis was observed in 57% and Grade 4 mucositis occurred in 5 (16.7%). All adverse effects were reversible and no serious adverse events were prolonged. Among those responding to first-line therapy, 24 of the 30 (80%) achieved complete response (CR) and 6 (20%) partial response (PR), but no stable disease (SD) or no change (NC). Overall response was 100%. Histopathologically, 2 of 9 undergoing postchemoradiotherapy had no tumors. Clinical and pathological CR was 86.7%. Adverse events associated with this therapy associated events were considered relatively mild and within allowable limits. (author)

  12. Development of an optical inspection bench for the inspection of internal surfaces of 650 MHz SCRF cavities

    International Nuclear Information System (INIS)

    Kokil, S.V.; Kane, G.V.; Raghavendra, S.; Chauhan, S.K.; Rajpoot, D.S.; Oraon, B.; Om Prakash; Joshi, S.C.

    2015-01-01

    An optical inspection system has been developed for inspection of internal surfaces of 650 MHz superconducting RF cavities. The cavity parts are welded either using Electron Beam or Laser Beam Welding for making a good quality of weld joints. Surface defects like pits, scratches, welding spatters etc. on the internal surface of the cavity deteriorates cavity performance. Surface quality of the cavity equator joint plays an important role in the cavity performance. To study the quality of equator surface, the inspection bench offers high resolution images with a linear resolution of 45 m/pixel at a distance of ∼200 mm. The bench comprises of two major sub-systems, optical imaging system and cavity positioning system. A digital camera and multi coloured illumination system is used to obtain high resolution images. The camera is mounted inside a long cylindrical tube. The cylindrical tube can be inserted into a SCRF cavity. The length of the cylinder is long enough to inspect five-cell 650 MHz SCRF cavity. The cavity is placed on a set of PTFE rollers, which are mounted on a trolley. The cavity can be moved linearly with the help of ball screw-servomotor mechanism. The camera along with cylindrical tube can be rotated around its axis with a stepper motor to scan the cavity's internal surface. The paper presents the details about the optical inspection bench and optical inspection results. (author)

  13. Numerical simulations of radiation hydrodynamics and modeling of high temperature hohlraum cavities

    International Nuclear Information System (INIS)

    Gupta, N.K.; Godwal, B.K.

    2003-10-01

    A summary of our efforts towards the validation of radiation hydrodynamics and opacity models are presented. Effects of various parameters on the radiation temperature inside an inertial confinement fusion (ICF) hohlraum, the effects of non-local thermodynamic equilibrium conditions on emission and absorption, and the hydrodynamics of aluminium and gold foils driven by radiation are studied. LTE and non-LTE predictions for emitted radiation are compared with the experimental results and it is seen that non-LTE simulations show a marked improvement over LTE results. It is shown that the mixing of two high Z materials can lead to an enhancement in the Rosseland mean. An experimental study of soft x-ray emission from laser-irradiated Au-Cu mix-Z targets confirmed these predictions. It is seen that only multi group non-LTE radiation transport is able to explain experimentally observed features in the conversion efficiency of laser light to x-rays. One group radiation transport under predicts the radiation temperature. It is shown that erroneous results can be obtained if the space mesh in the hohlraum wall is not fine enough. Hydrodynamics of a wedge shaped aluminium foil driven by the hohlraum radiation is also presented and results are compared with NOVA laser experiments. Laser driven shock wave EOS and gold hohlraum experiments carried out at CAT are analyzed and they confirmed our theoretical estimates. (author)

  14. Superconducting cavity material for the European XFEL

    Science.gov (United States)

    Singer, W.; Singer, X.; Brinkmann, A.; Iversen, J.; Matheisen, A.; Navitski, A.; Tamashevich, Y.; Michelato, P.; Monaco, L.

    2015-08-01

    Analysis of the strategy for superconducting cavity material procurement and quality management is done on the basis of the experience with the cavity production for the European x-ray free electron laser (EXFEL) facility. An adjustment of the material specification to EXFEL requirements, procurement of material, quality control (QC), documentation, and shipment to cavity producers have been worked out and carried out by DESY. A multistep process of qualification of the material suppliers included detailed material testing, single- and nine-cell cavity fabrication, and cryogenic radiofrequency tests. Production of about 25 000 semi-finished parts of high purity niobium and niobium-titanium alloy in a period of three years has been divided finally between companies Heraeus, Tokyo Denkai, Ningxia OTIC, and PLANSEE. Consideration of large-grain (LG) material as a possible option for the EXFEL has resulted in the production of one cryogenic module consisting of seven (out of eight) LG cavities. LG materials fulfilled the EXFEL requirements and showed even 25% to 30% higher unloaded quality factor. A possible shortage of the required quantity of LG material on the market led, however, to the choice of conventional fine-grain (FG) material. Eddy-current scanning (ECS) has been applied as an additional QC tool for the niobium sheets and contributed significantly to the material qualification and sorting. Two percent of the sheets have been rejected, which potentially could affect up to one-third of the cavities. The main imperfections and defects in the rejected sheets have been analyzed. Samples containing foreign material inclusions have been extracted from the sheets and electrochemically polished. Some inclusions remained even after 150 μm surface layer removal. Indications of foreign material inclusions have been found in the industrially fabricated and treated cavities and a deeper analysis of the defects has been performed.

  15. Technical tasks in superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    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)

  16. Study of a power coupler for superconducting RF cavities used in high intensity proton accelerator; Etude et developpement d'un coupleur de puissance pour les cavites supraconductrices destinees aux accelerateurs de protons de haute intensite

    Energy Technology Data Exchange (ETDEWEB)

    Souli, M

    2007-07-15

    The coaxial power coupler needed for superconducting RF cavities used in the high energy section of the EUROTRANS driver should transmit 150 kW (CW operation) RF power to the protons beam. The calculated RF and dielectric losses in the power coupler (inner and outer conductor, RF window) are relatively high. Consequently, it is necessary to design very carefully the cooling circuits in order to remove the generated heat and to ensure stable and reliable operating conditions for the coupler cavity system. After calculating all type of losses in the power coupler, we have designed and validated the inner conductor cooling circuit using numerical simulations results. We have also designed and optimized the outer conductor cooling circuit by establishing its hydraulic and thermal characteristics. Next, an experiment dedicated to study the thermal interaction between the power coupler and the cavity was successfully performed at CRYOHLAB test facility. The critical heat load Qc for which a strong degradation of the cavity RF performance was measured leading to Q{sub c} in the range 3 W-5 W. The measured heat load will be considered as an upper limit of the residual heat flux at the outer conductor cold extremity. A dedicated test facility was developed and successfully operated for measuring the performance of the outer conductor heat exchanger using supercritical helium as coolant. The test cell used reproduces the realistic thermal boundary conditions of the power coupler mounted on the cavity in the cryo-module. The first experimental results have confirmed the excellent performance of the tested heat exchanger. The maximum residual heat flux measured was 60 mW for a 127 W thermal load. As the RF losses in the coupler are proportional to the incident RF power, we can deduce that the outer conductor heat exchanger performance is continued up to 800 kW RF power. Heat exchanger thermal conductance has been identified using a 2D axisymmetric thermal model by comparing

  17. High performance carbon nanocomposites for ultracapacitors

    Science.gov (United States)

    Lu, Wen

    2012-10-02

    The present invention relates to composite electrodes for electrochemical devices, particularly to carbon nanotube composite electrodes for high performance electrochemical devices, such as ultracapacitors.

  18. Physics and chemistry of niobium materials in the context of superconducting RF cavity applications

    International Nuclear Information System (INIS)

    Roy, S.B.

    2016-01-01

    Superconducting radio frequency (SCRF) cavities excel over the normal conducting RF cavities in the long pulse or continuous wave high energy particle accelerations, and niobium (Nb) is currently the material of choice for fabrication of such SCRF cavities. However the accelerating gradients attained in the Nb SCRF cavities deployed in various high energy particle accelerators are significantly below the theoretical limit predicted by the superconducting properties of Nb. Thus it is very important to understand the physics and chemistry of Nb materials in some details so as to maximize the SCRF cavity performance. This abstract will discuss some issues which help in the development of high gradient and energy efficient Nb SCRF cavities in a cost effective manner. (author)

  19. Strategies and Experiences Using High Performance Fortran

    National Research Council Canada - National Science Library

    Shires, Dale

    2001-01-01

    .... High performance Fortran (HPF) is a relative new addition to the Fortran dialect It is an attempt to provide an efficient high-level Fortran parallel programming language for the latest generation of been debatable...

  20. Review of ingot niobium as a material for superconducting radiofrequency accelerating cavities

    Energy Technology Data Exchange (ETDEWEB)

    Kneisel, P., E-mail: kneisel@jlab.org [Jefferson Lab, Newport News, VA 23606 (United States); Ciovati, G.; Dhakal, P. [Jefferson Lab, Newport News, VA 23606 (United States); Saito, K. [Michigan State University, East Lansing, MI 48824 (United States); Singer, W.; Singer, X. [DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Myneni, G.R., E-mail: rao@jlab.org [Jefferson Lab, Newport News, VA 23606 (United States)

    2015-02-21

    As a result of collaboration between Jefferson Lab and niobium manufacturer Companhia Brasileira de Metalurgia e Mineração (CBMM), ingot niobium was explored as a possible material for superconducting radiofrequency (SRF) cavity fabrication. The first single cell cavity from large-grain high purity niobium was fabricated and successfully tested at Jefferson Lab in 2004. This work triggered research activities in other SRF laboratories around the world. Large-grain (LG) niobium became not only an interesting alternative material for cavity builders, but also material scientists and surface scientists were eager to participate in the development of this technology. Many single cell cavities made from material of different suppliers have been tested successfully and several multi-cell cavities have shown performances comparable to the best cavities made from standard fine-grain niobium. Several 9-cell cavities fabricated by Research Instruments and tested at DESY exceeded the best performing fine grain cavities with a record accelerating gradient of E{sub acc}=45.6 MV/m. The quality factor of those cavities was also higher than that of fine-grain (FG) cavities processed with the same methods. Such performance levels push the state-of-the art of SRF technology and are of great interest for future accelerators. This contribution reviews the development of ingot niobium technology and highlights some of the differences compared to standard FG material and opportunities for further developments.

  1. An improved oxygen diffusion model to explain the effect of low-temperature baking on high field losses in niobium superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi

    2006-07-01

    Radio-frequency (RF) superconducting cavities made of high purity niobium are widely used to accelerate charged particle beams in particle accelerators. The major limitation to achieve RF field values approaching the theoretical limit for niobium is represented by ''anomalous'' losses which degrade the quality factor of the cavities starting at peak surface magnetic fields of about 100 mT, in absence of field emission. These high field losses are often referred to as ''Q-drop''. It has been observed that the Q-drop is drastically reduced by baking the cavities at 120 C for about 48 h under ultrahigh vacuum. An improved oxygen diffusion model for the niobium-oxide system is proposed to explain the benefit of the low-temperature baking on the Q-drop in niobium superconducting rf cavities. The model shows that baking at 120 C for 48 h allows oxygen to diffuse away from the surface, and therefore increasing the lower critical field towards the value for pure niobium.

  2. A SURVEY OF CORONAL CAVITY DENSITY PROFILES

    International Nuclear Information System (INIS)

    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.

  3. High Performance Grinding and Advanced Cutting Tools

    CERN Document Server

    Jackson, Mark J

    2013-01-01

    High Performance Grinding and Advanced Cutting Tools discusses the fundamentals and advances in high performance grinding processes, and provides a complete overview of newly-developing areas in the field. Topics covered are grinding tool formulation and structure, grinding wheel design and conditioning and applications using high performance grinding wheels. Also included are heat treatment strategies for grinding tools, using grinding tools for high speed applications, laser-based and diamond dressing techniques, high-efficiency deep grinding, VIPER grinding, and new grinding wheels.

  4. Strategy Guideline: High Performance Residential Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Holton, J.

    2012-02-01

    The Strategy Guideline: High Performance Residential Lighting has been developed to provide a tool for the understanding and application of high performance lighting in the home. The high performance lighting strategies featured in this guide are drawn from recent advances in commercial lighting for application to typical spaces found in residential buildings. This guide offers strategies to greatly reduce lighting energy use through the application of high quality fluorescent and light emitting diode (LED) technologies. It is important to note that these strategies not only save energy in the home but also serve to satisfy the homeowner's expectations for high quality lighting.

  5. Carbon nanomaterials for high-performance supercapacitors

    OpenAIRE

    Tao Chen; Liming Dai

    2013-01-01

    Owing to their high energy density and power density, supercapacitors exhibit great potential as high-performance energy sources for advanced technologies. Recently, carbon nanomaterials (especially, carbon nanotubes and graphene) have been widely investigated as effective electrodes in supercapacitors due to their high specific surface area, excellent electrical and mechanical properties. This article summarizes the recent progresses on the development of high-performance supercapacitors bas...

  6. Reducing the asymmetry in coupled cavity of linear accelerator

    International Nuclear Information System (INIS)

    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)

  7. Simultaneous frequency stabilization and high-power dense wavelength division multiplexing (HP-DWDM) using an external cavity based on volume Bragg gratings (VBGs)

    Science.gov (United States)

    Hengesbach, Stefan; Klein, Sarah; Holly, Carlo; Witte, Ulrich; Traub, Martin; Hoffmann, Dieter

    2016-03-01

    Multiplexing technologies enable the development of high-brightness diode lasers for direct industrial applications. We present a High-Power Dense Wavelength Division Multiplexer (HP-DWDM) with an average channel spacing of 1.7 (1.5) nm and a subsequent external cavity mirror to provide feedback for frequency stabilization and multiplexing in one step. The "self-optimizing" multiplexing unit consists of four reflective Volume Bragg Gratings (VBGs) with 99% diffraction efficiency and seven dielectric mirrors to overlay the radiation of five input channels with an adjustable channel spacing of 1-2 nm. In detail, we focus on the analysis of the overall optical efficiency, the change of the beam parameter product and the spectral width. The performance is demonstrated using five 90 μm multimode 9xx single emitters with M2angular intensity distribution changes strongly and the beam parameter product decreases by a factor of 1.2 to 1.9. Thereby the angular intensity distribution is more affected than the width of the beam waist. The spectral width per emitter decreases to 3-200 pm (FWHM) depending on the injection current and the reflectance of the feedback mirror (0.75%, 1.5%, 4%, 6% or 8%). The overall optical multiplexing efficiency ranges between 77% and 86%. With some modifications (e.g. enhanced AR-coatings) we expect 90-95%.

  8. Conduction cooling systems for linear accelerator cavities

    Science.gov (United States)

    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.

  9. Team Development for High Performance Management.

    Science.gov (United States)

    Schermerhorn, John R., Jr.

    1986-01-01

    The author examines a team development approach to management that creates shared commitments to performance improvement by focusing the attention of managers on individual workers and their task accomplishments. It uses the "high-performance equation" to help managers confront shared beliefs and concerns about performance and develop realistic…

  10. Heat transfer in window frames with internal cavities

    Energy Technology Data Exchange (ETDEWEB)

    Gustavsen, Arild

    2001-07-01

    rates. From the results it appears that the thermal transmittance of a four-sided section can be found by calculating the average of the thermal transmittance of the respective single horizontal and vertical sections. In addition, it was found that two-dimensional conduction heat transfer simulation software agrees well with three-dimensional CFD simulations if the natural convection correlations used for the internal cavities are correct. Numerical simulations were done with natural convection in three-dimensional cavities with a high vertical aspect ratio and a low horizontal aspect ratio. The cavities studied had vertical aspect ratios of 20, 40, and 80 and horizontal aspect ratios ranging from 0.2 to 5. It was shown that three-dimensional cavities with a horizontal aspect ratio larger than five can be considered to be a two-dimensional cavity to within 4 % when considering heat transfer rates. Nusselt number correlations for the different horizontal aspect ratios are presented for cavities with vertical aspect ratios of 20 and 40. Complex multicellular flow was studied for the case where the vertical and horizontal aspect ratios were 40 and 2, respectively. Experimental studies included the normal spectral and total emissivity of specimens from six meter long untreated and anodized aluminum profiles. Specimens facing the internal cavities (thermal break cavity and all aluminum cavity) were measured. Some masking tapes often used in hot box experiments were also measured. The normal total emissivity was found to be is fairly constant (between 0.834 and 0.856) for exterior parts of the anodized profile and for surfaces facing the thermal break cavity. The normal total emissivity of the all-aluminum internal cavities was found to vary between 0.055 and 0.82. The experiments were performed with a Fourier transform infrared spectrometer in the wavelength interval from 4.5 to 40 mm. (author)

  11. State of the art of multicell SC cavities and perspectives

    International Nuclear Information System (INIS)

    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

  12. Nonlocal Intracranial Cavity Extraction

    Science.gov (United States)

    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

  13. Nonlocal Intracranial Cavity Extraction

    Directory of Open Access Journals (Sweden)

    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.

  14. Delivering high performance BWR fuel reliably

    Energy Technology Data Exchange (ETDEWEB)

    Schardt, J.F. [GE Nuclear Energy, Wilmington, NC (United States)

    1998-07-01

    Utilities are under intense pressure to reduce their production costs in order to compete in the increasingly deregulated marketplace. They need fuel, which can deliver high performance to meet demanding operating strategies. GE's latest BWR fuel design, GE14, provides that high performance capability. GE's product introduction process assures that this performance will be delivered reliably, with little risk to the utility. (author)

  15. HPTA: High-Performance Text Analytics

    OpenAIRE

    Vandierendonck, Hans; Murphy, Karen; Arif, Mahwish; Nikolopoulos, Dimitrios S.

    2017-01-01

    One of the main targets of data analytics is unstructured data, which primarily involves textual data. High-performance processing of textual data is non-trivial. We present the HPTA library for high-performance text analytics. The library helps programmers to map textual data to a dense numeric representation, which can be handled more efficiently. HPTA encapsulates three performance optimizations: (i) efficient memory management for textual data, (ii) parallel computation on associative dat...

  16. Foundations for quantitative microstructural models to track evolution of the metallurgical state during high purity Nb cavity fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Bieler, Thomas R [Michigan State University; Wright, Neil T [Michigan State University; Compton, Chris C [Facility for Rare Isotope Beams

    2014-03-15

    The goal of the Materials Science SRF Cavity Group of Michigan State University and the National Superconducting Cyclotron has been (and continues to be) to understand quantitatively the effects of process history on functional properties. These relationships were assessed via studies on Nb samples and cavity parts, which had various combinations of forming processes, welding, heat treatments, and surface preparation. A primary focus was on large-grain cavity building strategies. Effects of processing operations and exposure to hydrogen on the thermal conductivity has been identified in single and bi-crystal samples, showing that the thermal conductivity can be altered by a factor of 5 depending on process history. Characterization of single crystal tensile samples show a strong effect of crystal orientation on deformation resistance and shape changes. Large grain half cells were examined to characterize defect content and surface damage effects, which provided quantitative information about the depth damage layers from forming.

  17. Self-Assembly of Chip-Size Components with Cavity Structures: High-Precision Alignment and Direct Bonding without Thermal Compression for Hetero Integration

    Directory of Open Access Journals (Sweden)

    Mitsumasa Koyanagi

    2011-02-01

    Full Text Available New surface mounting and packaging technologies, using self-assembly with chips having cavity structures, were investigated for three-dimensional (3D and hetero integration of complementary metal-oxide semiconductors (CMOS and microelectromechanical systems (MEMS. By the surface tension of small droplets of 0.5 wt% hydrogen fluoride (HF aqueous solution, the cavity chips, with a side length of 3 mm, were precisely aligned to hydrophilic bonding regions on the surface of plateaus formed on Si substrates. The plateaus have micro-channels to readily evaporate and fully remove the liquid from the cavities. The average alignment accuracy of the chips with a 1 mm square cavity was found to be 0.4 mm. The alignment accuracy depends, not only on the area of the bonding regions on the substrates and the length of chip periphery without the widths of channels in the plateaus, but also the area wetted by the liquid on the bonding regions. The precisely aligned chips were then directly bonded to the substrates at room temperature without thermal compression, resulting in a high shear bonding strength of more than 10 MPa.

  18. Electron beam weld parameter set development and cavity cost

    International Nuclear Information System (INIS)

    John Brawley; John Mammossor; Larry Philips

    1997-01-01

    Various methods have recently been considered for use in the cost-effective manufacturing of large numbers of niobium cavities. A method commonly assumed to be too expensive is the joining of half cells by electron beam welding (EBW), as has been done with multipurpose EBW equipment for producing small numbers of cavities at accelerator laboratories. The authors have begun to investigate the advantages that would be available if a single-purpose, task-specific EBW processing tool were used to produce cavities in a high-volume commercial-industrial context. For such a tool and context they have sought to define an EBW parameter set that is cost-effective not only in terms of per-cavity production cost, but also in terms of the minimization of quench-producing weld defects. That is, they define cavity cost-effectiveness to include both production and performance costs. For such an EBW parameter set, they have developed a set of ideal characteristics, produced and tested samples and a complete cavity, studied the weld-defect question, and obtained industrial estimates of cavity high-volume production costs. The investigation in ongoing. This paper reports preliminary findings

  19. Probing the fundamental limit of niobium in high radiofrequency fields by dual mode excitation in superconducting radiofrequency cavities

    International Nuclear Information System (INIS)

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari

    2011-01-01

    We have studied thermal breakdown in several multicell superconducting radiofrequency cavity by simultaneous excitation of two TM 010 passband modes. Unlike measurements done in the past, which indicated a clear thermal nature of the breakdown, our measurements present a more complex picture with interplay of both thermal and magnetic effects. JLab LG-1 that we studied was limited at 40.5 MV/m, corresponding to B peak = 173 mT, in 89 mode. Dual mode measurements on this quench indicate that this quench is not purely magnetic, and so we conclude that this field is not the fundamental limit in SRF cavities

  20. Filling a Conical Cavity

    Science.gov (United States)

    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.

  1. A study of performance parameters on drag and heat flux reduction efficiency of combinational novel cavity and opposing jet concept in hypersonic flows

    Science.gov (United States)

    Sun, Xi-wan; Guo, Zhen-yun; Huang, Wei; Li, Shi-bin; Yan, Li

    2017-02-01

    The drag reduction and thermal protection system applied to hypersonic re-entry vehicles have attracted an increasing attention, and several novel concepts have been proposed by researchers. In the current study, the influences of performance parameters on drag and heat reduction efficiency of combinational novel cavity and opposing jet concept has been investigated numerically. The Reynolds-average Navier-Stokes (RANS) equations coupled with the SST k-ω turbulence model have been employed to calculate its surrounding flowfields, and the first-order spatially accurate upwind scheme appears to be more suitable for three-dimensional flowfields after grid independent analysis. Different cases of performance parameters, namely jet operating conditions, freestream angle of attack and physical dimensions, are simulated based on the verification of numerical method, and the effects on shock stand-off distance, drag force coefficient, surface pressure and heat flux distributions have been analyzed. This is the basic study for drag reduction and thermal protection by multi-objective optimization of the combinational novel cavity and opposing jet concept in hypersonic flows in the future.

  2. Strategy Guideline. Partnering for High Performance Homes

    Energy Technology Data Exchange (ETDEWEB)

    Prahl, Duncan [IBACOS, Inc., Pittsburgh, PA (United States)

    2013-01-01

    High performance houses require a high degree of coordination and have significant interdependencies between various systems in order to perform properly, meet customer expectations, and minimize risks for the builder. Responsibility for the key performance attributes is shared across the project team and can be well coordinated through advanced partnering strategies. For high performance homes, traditional partnerships need to be matured to the next level and be expanded to all members of the project team including trades, suppliers, manufacturers, HERS raters, designers, architects, and building officials as appropriate. This guide is intended for use by all parties associated in the design and construction of high performance homes. It serves as a starting point and features initial tools and resources for teams to collaborate to continually improve the energy efficiency and durability of new houses.

  3. Diagram of a LEP superconducting cavity

    CERN Multimedia

    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.

  4. High-performance ceramics. Fabrication, structure, properties

    International Nuclear Information System (INIS)

    Petzow, G.; Tobolski, J.; Telle, R.

    1996-01-01

    The program ''Ceramic High-performance Materials'' pursued the objective to understand the chaining of cause and effect in the development of high-performance ceramics. This chain of problems begins with the chemical reactions for the production of powders, comprises the characterization, processing, shaping and compacting of powders, structural optimization, heat treatment, production and finishing, and leads to issues of materials testing and of a design appropriate to the material. The program ''Ceramic High-performance Materials'' has resulted in contributions to the understanding of fundamental interrelationships in terms of materials science, which are summarized in the present volume - broken down into eight special aspects. (orig./RHM)

  5. High Burnup Fuel Performance and Safety Research

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Je Keun; Lee, Chan Bok; Kim, Dae Ho (and others)

    2007-03-15

    The worldwide trend of nuclear fuel development is to develop a high burnup and high performance nuclear fuel with high economies and safety. Because the fuel performance evaluation code, INFRA, has a patent, and the superiority for prediction of fuel performance was proven through the IAEA CRP FUMEX-II program, the INFRA code can be utilized with commercial purpose in the industry. The INFRA code was provided and utilized usefully in the universities and relevant institutes domesticallly and it has been used as a reference code in the industry for the development of the intrinsic fuel rod design code.

  6. An economical wireless cavity-nest viewer

    Science.gov (United States)

    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...

  7. ADVANCED HIGH PERFORMANCE SOLID WALL BLANKET CONCEPTS

    International Nuclear Information System (INIS)

    WONG, CPC; MALANG, S; NISHIO, S; RAFFRAY, R; SAGARA, S

    2002-01-01

    OAK A271 ADVANCED HIGH PERFORMANCE SOLID WALL BLANKET CONCEPTS. First wall and blanket (FW/blanket) design is a crucial element in the performance and acceptance of a fusion power plant. High temperature structural and breeding materials are needed for high thermal performance. A suitable combination of structural design with the selected materials is necessary for D-T fuel sufficiency. Whenever possible, low afterheat, low chemical reactivity and low activation materials are desired to achieve passive safety and minimize the amount of high-level waste. Of course the selected fusion FW/blanket design will have to match the operational scenarios of high performance plasma. The key characteristics of eight advanced high performance FW/blanket concepts are presented in this paper. Design configurations, performance characteristics, unique advantages and issues are summarized. All reviewed designs can satisfy most of the necessary design goals. For further development, in concert with the advancement in plasma control and scrape off layer physics, additional emphasis will be needed in the areas of first wall coating material selection, design of plasma stabilization coils, consideration of reactor startup and transient events. To validate the projected performance of the advanced FW/blanket concepts the critical element is the need for 14 MeV neutron irradiation facilities for the generation of necessary engineering design data and the prediction of FW/blanket components lifetime and availability

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Heat performance resulting from combined effects of radiation and mixed convection in a rectangular cavity ventilated by injection or suction

    Science.gov (United States)

    Ezzaraa, K.; Bahlaoui, A.; Arroub, I.; Raji, A.; Hasnaoui, M.; Naïmi, M.

    2018-05-01

    In this work, we investigated numerically heat transfer by mixed convection coupled to thermal radiation in a vented rectangular enclosure uniformly heated from below with a constant heat flux. The fresh fluid is admitted into the cavity by injection or suction, by means of two openings located on the lower part of both right and left vertical sides. Another opening is placed on the middle of the top wall to ensure the ventilation. Air, a radiatively transparent medium, is considered to be the cooling fluid. The inner surfaces, in contact with the fluid, are assumed to be gray, diffuse emitters and reflectors of radiation with identical emissivities. The effects of some pertinent parameters such as the Reynolds number, 300 ≤ Re ≤ 5000, and the emissivity of the walls, 0 ≤ ɛ ≤ 0.85, on flow and temperature patterns as well as on the heat transfer rate within the enclosure are presented for the two ventilation modes (injection and suction). The results indicate that the flow and thermal structures are affected by the thermal radiation for the two modes of imposed flow. However, the suction mode is found to be more favorable to the heat transfer in comparison with the injection one.

  10. High performance liquid chromatographic determination of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-02-08

    ) high performance liquid chromatography (HPLC) grade .... applications. These are important requirements if the reagent is to be applicable to on-line pre or post column derivatisation in a possible automation of the analytical.

  11. Analog circuit design designing high performance amplifiers

    CERN Document Server

    Feucht, Dennis

    2010-01-01

    The third volume Designing High Performance Amplifiers applies the concepts from the first two volumes. It is an advanced treatment of amplifier design/analysis emphasizing both wideband and precision amplification.

  12. High-performance computing using FPGAs

    CERN Document Server

    Benkrid, Khaled

    2013-01-01

    This book is concerned with the emerging field of High Performance Reconfigurable Computing (HPRC), which aims to harness the high performance and relative low power of reconfigurable hardware–in the form Field Programmable Gate Arrays (FPGAs)–in High Performance Computing (HPC) applications. It presents the latest developments in this field from applications, architecture, and tools and methodologies points of view. We hope that this work will form a reference for existing researchers in the field, and entice new researchers and developers to join the HPRC community.  The book includes:  Thirteen application chapters which present the most important application areas tackled by high performance reconfigurable computers, namely: financial computing, bioinformatics and computational biology, data search and processing, stencil computation e.g. computational fluid dynamics and seismic modeling, cryptanalysis, astronomical N-body simulation, and circuit simulation.     Seven architecture chapters which...

  13. Embedded High Performance Scalable Computing Systems

    National Research Council Canada - National Science Library

    Ngo, David

    2003-01-01

    The Embedded High Performance Scalable Computing Systems (EHPSCS) program is a cooperative agreement between Sanders, A Lockheed Martin Company and DARPA that ran for three years, from Apr 1995 - Apr 1998...

  14. Gradient High Performance Liquid Chromatography Method ...

    African Journals Online (AJOL)

    Purpose: To develop a gradient high performance liquid chromatography (HPLC) method for the simultaneous determination of phenylephrine (PHE) and ibuprofen (IBU) in solid ..... nimesulide, phenylephrine. Hydrochloride, chlorpheniramine maleate and caffeine anhydrous in pharmaceutical dosage form. Acta Pol.

  15. Highlighting High Performance: Whitman Hanson Regional High School; Whitman, Massachusetts

    Energy Technology Data Exchange (ETDEWEB)

    2006-06-01

    This brochure describes the key high-performance building features of the Whitman-Hanson Regional High School. The brochure was paid for by the Massachusetts Technology Collaborative as part of their Green Schools Initiative. High-performance features described are daylighting and energy-efficient lighting, indoor air quality, solar and wind energy, building envelope, heating and cooling systems, water conservation, and acoustics. Energy cost savings are also discussed.

  16. Predictions of laminar natural convection in heated cavities

    International Nuclear Information System (INIS)

    Winters, K.H.

    1982-06-01

    Several examples of laminar, natural convection in heated cavities are discussed with illustrative calculations. These include convection in a square cavity at high Rayleigh number; in a narrow cavity at moderate aspect ratio; in a rectangular cavity heated from below; in a trapezoidal cavity, and in a rectangular cavity containing a conducting obstruction. The steady equations for the velocity, pressure and temperature are solved in the Boussinesq approximation, using a standard Galerkin formulation of the finite-element method. (author)

  17. High performance computing in Windows Azure cloud

    OpenAIRE

    Ambruš, Dejan

    2013-01-01

    High performance, security, availability, scalability, flexibility and lower costs of maintenance have essentially contributed to the growing popularity of cloud computing in all spheres of life, especially in business. In fact cloud computing offers even more than this. With usage of virtual computing clusters a runtime environment for high performance computing can be efficiently implemented also in a cloud. There are many advantages but also some disadvantages of cloud computing, some ...

  18. High-performance computing — an overview

    Science.gov (United States)

    Marksteiner, Peter

    1996-08-01

    An overview of high-performance computing (HPC) is given. Different types of computer architectures used in HPC are discussed: vector supercomputers, high-performance RISC processors, various parallel computers like symmetric multiprocessors, workstation clusters, massively parallel processors. Software tools and programming techniques used in HPC are reviewed: vectorizing compilers, optimization and vector tuning, optimization for RISC processors; parallel programming techniques like shared-memory parallelism, message passing and data parallelism; and numerical libraries.

  19. An inter-comparison of HO2 measured by Fluorescence Assay by Gas Expansion and Cavity Ringdown Spectroscopy in the Highly Instrumented Reactor for Atmospheric Chemistry.

    Science.gov (United States)

    Brennan, A.; Onel, L. C.; Gianella, M.; Ronnie, G.; Aguila, A. L.; Hancock, G.; Whalley, L.; Seakins, P. W.; Ritchie, G.; Heard, D. E.

    2017-12-01

    HO2 is an important species in the atmosphere, as it is involved in the HOx radical reaction cycle that is critical to the oxidation of atmospheric pollutants and the ultimate cleaning of the troposphere. One of the most widely utilised methods to measure HO2 is Fluorescence Assay by Gas Expansion (FAGE), which indirectly measures HO2 by sampling into a low pressure cell and titrating HO2 with NO to produce OH that is then detected by Laser Induced Fluorescence. This is an indirect and non-absolute detection technique that requires careful calibration to convert the measured signal into [HO2], which involves the photolysis of H2O at 185 nm to produce OH and HO2, and is subject to 30 % errors at 2σ level. The work presented here shows the validation of the FAGE technique and its calibration procedure through inter-comparison experiments between the non-absolute FAGE technique and Cavity Ringdown Spectroscopy (CRDS), an absolute absorption based method. The CRDS system was used to excite the first O-H overtone of the HO2 absorption band at 1506.43 nm, and features a cavity length of 1.2 m and a total path of 60 km. The experiments were performed inside the 2.25 m3 stainless steel Highly Instrumented Reactor for Atmospheric Chemistry (HIRAC), using a synthetic air mixture at 150 and 1000 mbar of pressure and 298 K. HO2 was generated by photolysis of Cl2 at 365 nm in the presence of CH3OH and O2, and the [HO2] was monitored using both instruments. Additionally, monitoring the temporal decay of HO2 during its self-reaction provided an alternative calibration method for the FAGE instrument, and allowed the absorption cross section of HO2 at 1506.43 nm, σHO2, to be measured. FAGE calibration factors determined through the second order decays of HO2 at 1000 mbar agreed within 8 % of the H2O photolysis method, and determinations of σHO2 at 150 and 1000 mbar agree with previously reported data within 20 % and 12 % respectively. [HO2] correlation plots between the two

  20. Governance among Malaysian high performing companies

    Directory of Open Access Journals (Sweden)

    Asri Marsidi

    2016-07-01

    Full Text Available Well performed companies have always been linked with effective governance which is generally reflected through effective board of directors. However many issues concerning the attributes for effective board of directors remained unresolved. Nowadays diversity has been perceived as able to influence the corporate performance due to the likelihood of meeting variety of needs and demands from diverse customers and clients. The study therefore aims to provide a fundamental understanding on governance among high performing companies in Malaysia.