Beam orbit control in TESLA superconducting cavities from dipole mode measurements

International Nuclear Information System (INIS)

Paparella, R.

2006-09-01

The knowledge of the electromagnetic interaction between a beam and the surrounding vacuum chamber is necessary in order to optimize the accelerator performance in terms of stored current. Many instability phenomena may occur in the machine because of the fields produced by the beam and acting back on itself. Basically, these fields, wake-fields, produce an extra voltage, affecting the longitudinal dynamics, and a transverse kick which deflects the beam. In this thesis we present the results of theoretical and experimental investigations to demonstrate the possibility of using the dipolar wake fields of the superconducting accelerating to measure the beam transverse position. After an introduction to the ILC project and to the TESLA technology, of superconducting RF cavities, we will approach the problem from an analytical point of view in chapter 2. The expression of the wake fields in a cylindrical cavity will be investigated and the electromagnetic field modes derived from Maxwell equations in an original way. Graphical solutions of a Matlab program simulating the fields due to a particle passing through a pill-box cavity along a generic path will be shown. The interaction of the beam with higher order modes (HOM) in the TESLA cavities has been studied in the past at the TESLA Test Facility (TTF) in order to determine whether the modes with the highest loss factor are sufficiently damped. Starting from the results obtained before 2003, HOM signals has been better observed and examined in order to use dipole modes to find the electric center of each cavity in the first TTF accelerating module. The results presented in chapter 3 will show that by monitoring the HOM signal amplitude for two polarizations of a dipole mode, one can measure electrical center of the modes with a resolution of 50 μm. Moreover, a misalignment of the first TTF module with respect to the gun axis has been predicted using cavity dipole modes. Alternatives to this method are described in

Cavity-Type BPMs For The TESLA Test Facility Free Electron Laser

CERN Document Server

Waldmann, H

2003-01-01

For measurements of the beam position at the undulator section of the TESLA Test Facility (TTF) at DESY cavity-type beam position monitors were developed, installed and brought into operation. Besides of some theoretical aspects results of in-beam measurements at the TTF are presented and pros and cons of this monitor concept are discussed.

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)

Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities

International Nuclear Information System (INIS)

Bane, K

2008-01-01

In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm

Cryogenic Current Comparator for Absolute Measurement of the Dark Current of the Superconducting Cavities for Tesla

CERN Document Server

Knaack, K; Wittenburg, K

2003-01-01

A newly high performance SQUID based measurement system for detecting dark currents, generated by superconducting cavities for TESLA is proposed. It makes use of the Cryogenic Current Comparator principle and senses dark currents in the nA range with a small signal bandwidth of 70 kHz. To reach the maximum possible energy in the TESLA project is a strong motivation to push the gradients of the superconducting cavities closer to the physical limit of 50 MV/m. The field emission of electrons (the so called dark current) of the superconducting 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. This contribution describes a Cryogenic Current Comparator (CCC) as an excellent and useful tool for this purpose. The most important component of the CCC is a high performance DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the extracted ...

Diagnostics Upgrades for Investigations of HOM Effects in TESLA-type SCRF Cavities

Energy Technology Data Exchange (ETDEWEB)

Lumpkin, A. H. [Fermilab; Edstrom Jr., D.; Ruan, J. [Fermilab; Thurman-Keup, R. [Fermilab; Shin, Y. [Fermilab; Prieto, P. [Fermilab; Eddy, N. [Fermilab; Carlsten, B. E. [Los Alamos

2017-08-23

We describe the upgrades to diagnostic capabilities on the Fermilab Accelerator Science and Technology (FAST) electron linear accelerator that will allow investigations of the effects of high-order modes (HOMs) in SCRF cavities on macropulse-average beam quality. We examine the dipole modes in the first pass-band generally observed in the 1.6-1.9 GHz regime for TESLA-type SCRF cavities due to uniform transverse beam offsets of the electron beam. Such cavities are the basis of the accelerators such as the European XFEL and the proposed MaRIE XFEL facility. Preliminary HOM detector data, prototype BPM test data, and first framing camera OTR data with ~20- micron spatial resolution at 250 pC per bunch will be presented.

Electropolishing on single-cell: (TESLA, Reentrant and Low Loss shapes) Comsol modelling

International Nuclear Information System (INIS)

Bruchon, M.

2007-01-01

In the framework of improvement of cavity electropolishing, modelling permits to evaluate some parameters not easily accessible by experiments and can also help us to guide them. Different laboratories (DESY, Fermilab) work on electro or chemical polishing modelling with different approaches and softwares. At CEA Saclay, COMSOL software is used to model horizontal electropolishing of cavity in two dimensions. The goal of this study has been motivated by improvement of our electropolishing setup by modifying the arrival of the acid. The influence of a protuberant cathode has been evaluated and compared for different shapes of single cell cavities: TESLA, ILC Low Loss (LL ILC ), and ILC Reentrant (RE ILC ). (author)

Test measurement of a new TESLA cavity beam position monitor at the ELBE linac

International Nuclear Information System (INIS)

Sargsyan, V.; Schreiber, H.J.; Evtushenko, P.; Schurig, R.

2004-01-01

A new type of a cavity BPM proposed for beam position determination along the TESLA linac was tested at the accelerator ELBE in Rossendorf / Dresden. Measurements using an improved BPM (large and stable cross-talk isolation, significantly less energy dissipation, a novel LO signal generation) were performed in single- and multi-bunch regimes. Agreement with expectations was found. The low bunch charge available allowed for preliminary measurements on sensitivity and position resolution, which extrapolated to TESLA would ful l the demands for precise bunch-to-bunch position determination. Possible improvements, in particular on the signal processing scheme, are also discussed. (orig.)

Linear Colliders TESLA

International Nuclear Information System (INIS)

Anon.

1994-01-01

The aim of the TESLA (TeV Superconducting Linear Accelerator) collaboration (at present 19 institutions from seven countries) is to establish the technology for a high energy electron-positron linear collider using superconducting radiofrequency cavities to accelerate its beams. Another basic goal is to demonstrate that such a collider can meet its performance goals in a cost effective manner. For this the TESLA collaboration is preparing a 500 MeV superconducting linear test accelerator at the DESY Laboratory in Hamburg. This TTF (TESLA Test Facility) consists of four cryomodules, each approximately 12 m long and containing eight 9-cell solid niobium cavities operating at a frequency of 1.3 GHz

The TESLA RF System

International Nuclear Information System (INIS)

Choroba, S.

2003-01-01

The TESLA project proposed by the TESLA collaboration in 2001 is a 500 to 800GeV e+/e- linear collider with integrated free electron laser facility. The accelerator is based on superconducting cavity technology. Approximately 20000 superconducting cavities operated at 1.3GHz with a gradient of 23.4MV/m or 35MV/m will be required to achieve the energy of 500GeV or 800GeV respectively. For 500GeV ∼600 RF stations each generating 10MW of RF power at 1.3GHz at a pulse duration of 1.37ms and a repetition rate of 5 or 10Hz are required. The original TESLA design was modified in 2002 and now includes a dedicated 20GeV electron accelerator in a separate tunnel for free electron laser application. The TESLA XFEL will provide XFEL radiation of unprecedented peak brilliance and full transverse coherence in the wavelength range of 0.1 to 6.4nm at a pulse duration of 100fs. The technology of both accelerators, the TESLA linear collider and the XFEL, will be identical, however the number of superconducting cavities and RF stations for the XFEL will be reduced to 936 and 26 respectively. This paper describes the layout of the entire RF system of the TESLA linear collider and the TESLA XFEL and gives an overview of its various subsystems and components

Measurement and adjustment of dumb-bells for 9-cell TESLA cavity

International Nuclear Information System (INIS)

Xu Wencan; Quan Shengwen; Hao Jiankui; Jiang Tao; Zhang Baocheng; Zhao Kui

2008-01-01

Correct Dumb-bells are very important to make sure the right field flatness, frequency of TM010 mode and length of 9-cell TESLA cavity. The shape of the dumb-bells will be wrong due to deep drawing, machining and EB welding. Then, the dumb-bells should be adjusted after iris and stiffness welding according to the mechanical and microwave measurement. Peking University has set up facilities for measuring and correcting the dumb-bells. This paper discusses the method of measuring and correcting the dumb-bells. (authors)

Cryomodule tests of four Tesla-like cavities in the Superconducting RF Test Facility at KEK

Directory of Open Access Journals (Sweden)

Eiji Kako

2010-04-01

Full Text Available A 6-m cryomodule including four Tesla-like cavities was developed, and was tested in the Superconducting RF Test Facility phase-I at KEK. The performance as a total superconducting cavity system was checked in the cryomodule tests at 2 K with high rf power. One of the four cavities achieved a stable pulsed operation at 32  MV/m, which is higher than the operating accelerating gradient in the ILC. The maximum accelerating gradient (E_{acc,max⁡} obtained in the vertical cw tests was maintained or slightly improved in the cryomodule tests operating in a pulse mode. Compensation of the Lorentz force detuning at 31  MV/m was successfully demonstrated by a piezo tuner and predetuning.

Tesla coil theoretical model and experimental verification

OpenAIRE

Voitkans, Janis; Voitkans, Arnis

2014-01-01

Abstract – In this paper a theoretical model of a Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wired format, where the line voltage is measured against electrically neutral space. It is shown that equivalent two-wired scheme can be found for a single-wired scheme and already known long line theory can be applied to a Tesla coil. Formulas for calculation of voltage in a Tesla coil by coordinate and calculation of resonance fre...

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...

Tesla Coil Theoretical Model and its Experimental Verification

Directory of Open Access Journals (Sweden)

Voitkans Janis

2014-12-01

Full Text Available In this paper a theoretical model of Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wire form, where the line voltage is measured across electrically neutral space. By applying the principle of equivalence of single-wire and two-wire schemes an equivalent two-wire scheme can be found for a single-wire scheme and the already known long line theory can be applied to the Tesla coil. A new method of multiple reflections is developed to characterize a signal in a long line. Formulas for calculation of voltage in Tesla coil by coordinate and calculation of resonance frequencies are proposed. The theoretical calculations are verified experimentally. Resonance frequencies of Tesla coil are measured and voltage standing wave characteristics are obtained for different output capacities in the single-wire mode. Wave resistance and phase coefficient of Tesla coil is obtained. Experimental measurements show good compliance with the proposed theory. The formulas obtained in this paper are also usable for a regular two-wire long line with distributed parameters.

Tesla Coil Theoretical Model and its Experimental Verification

OpenAIRE

Voitkans Janis; Voitkans Arnis

2014-01-01

In this paper a theoretical model of Tesla coil operation is proposed. Tesla coil is described as a long line with distributed parameters in a single-wire form, where the line voltage is measured across electrically neutral space. By applying the principle of equivalence of single-wire and two-wire schemes an equivalent two-wire scheme can be found for a single-wire scheme and the already known long line theory can be applied to the Tesla coil. A new method of multiple re...

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

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)

Superconducting magnet package for the TESLA test facility

International Nuclear Information System (INIS)

Koski, A.; Bandelmann, R.; Wolff, S.

1996-01-01

The magnetic lattice of the TeV electron superconducting linear accelerator (TESLA) will consist of superconducting quadrupoles for beam focusing and superconducting correction dipoles for beam steering, incorporated in the cryostats containing the superconducting cavities. This report describes the design of these magnets, presenting details of the magnetic as well as the mechanical design. The measured characteristics of the TESLA Test Facility (TTF) quadrupoles and dipoles are compared to the results obtained from numerical computations

Superconducting superstructure for the TESLA collider

Energy Technology Data Exchange (ETDEWEB)

Sekutowicz, J.; Tang, C. [DESY, MHF-SL, Hamburg (Germany); Ferrario, M. [INFN, Laboratori Nazionali di Frascati, Rome (Italy)

1998-04-01

The Authors discuss the new layout of a cavity chain (superstructure) allowing, the Authors hope, significant cost reduction of the RF system of both linacs of the TESLA linear collider. The proposed scheme increases the fill factor and thus makes an effective gradient of an accelerator higher. The authors present mainly computations that have performed up to now and which encouraged to order the copper model of the scheme, still keeping in mind that experiments with a beam will be necessary to prove if the proposed solution can be used for the acceleration.

Submacropulse electron-beam dynamics correlated with higher-order modes in Tesla-type superconducting rf cavities

Directory of Open Access Journals (Sweden)

A. H. Lumpkin

2018-06-01

Full Text Available We report the direct observations of submacropulse beam centroid oscillations correlated with higher order modes (HOMs which were generated by off-axis electron beam steering in TESLA-type superconducting rf cavities. The experiments were performed at the Fermilab Accelerator Science and Technology (FAST facility using its unique configuration of a photocathode rf gun injecting beam into two separated nine-cell cavities in series with corrector magnets and beam position monitors (BPMs located before, between, and after them. Oscillations of ∼100  kHz in the vertical plane and ∼380  kHz in the horizontal plane with up to 600-μm amplitudes were observed in a 3-MHz micropulse repetition rate beam with charges of 100, 300, 500, and 1000  pC/b. However, the effects were much reduced at 100  pC/b. The measurements were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch array data, imaging cameras, and a framing camera. Calculations reproduced the oscillation frequencies of the phenomena in the vertical case. In principle, these fundamental results may be scaled to cryomodule configurations of major accelerator facilities.

Photon collider at TESLA

International Nuclear Information System (INIS)

Telnov, Valery

2001-01-01

High energy photon colliders (γγ, γe) based on backward Compton scattering of laser light is a very natural addition to e + e - linear colliders. In this report, we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case, the γγ luminosity in the high energy part of spectrum can reach about (1/3)L e + e - . Typical cross-sections of interesting processes in γγ collisions are higher than those in e + e - collisions by about one order of magnitude, so the number of events in γγ collisions will be more than that in e + e - collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free electron laser is another option. However, a more straightforward solution is ''an optical storage ring (optical trap)'' with a diode pumped solid state laser injector which is today technically feasible. This paper briefly reviews the status of a photon collider based on the linear collider TESLA, its possible parameters and existing problems

TESLA Test Facility. Status

International Nuclear Information System (INIS)

Aune, B.

1996-01-01

The TESLA Test Facility (TTF), under construction at DESY by an international collaboration, is an R and D test bed for the superconducting option for future linear e+/e-colliders. It consists of an infrastructure to process and test the cavities and of a 500 MeV linac. The infrastructure has been installed and is fully operational. It includes a complex of clean rooms, an ultra-clean water plant, a chemical etching installation and an ultra-high vacuum furnace. The linac will consist of four cryo-modules, each containing eight 1 meter long nine-cell cavities operated at 1.3 GHz. The base accelerating field is 15 MV/m. A first injector will deliver a low charge per bunch beam, with the full average current (8 mA in pulses of 800 μs). A more powerful injector based on RF gun technology will ultimately deliver a beam with high charge and low emittance to allow measurements necessary to qualify the TESLA option and to demonstrate the possibility of operating a free electron laser based on the Self-Amplified-Spontaneous-Emission principle. Overview and status of the facility will be given. Plans for the future use of the linac are presented. (R.P.)

TESLA & ILC Cryomodules

Energy Technology Data Exchange (ETDEWEB)

Peterson, T. J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Weisend, II, J. G. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

2016-01-01

The TESLA collaboration developed a unique variant of SRF cryomodule designs, the chief feature being use of the large, low pressure helium vapor return pipe as the structural support backbone of the cryomodule. Additional innovative features include all cryogenic piping within the cryomodule (no parallel external cryogenic transfer line), long strings of RF cavities within a single cryomodule, and cryomodules connected in series. Several projects, including FLASH and XFEL at DESY, LCLS-II at SLAC, and the ILC technical design have adopted this general design concept. Advantages include saving space by eliminating the external transfer line, relatively tight packing of RF cavities along the beamline due to fewer warm-cold transitions, and potentially lower costs. However, a primary disadvantage is the relative lack of independence for warm-up, replacement, and cool-down of individual cryomodules.

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

Efficient model for low-energy transverse beam dynamics in a nine-cell 1.3 GHz cavity

International Nuclear Information System (INIS)

Hellert, Thorsten; Dohlus, Martin; Decking, Winfried

2017-10-01

FLASH and the European XFEL are SASE-FEL user facilities, at which superconducting TESLA cavities are operated in a pulsed mode to accelerate long bunch-trains. Several cavities are powered by one klystron. While the low-level rf system is able to stabilize the vector sum of the accelerating gradient of one rf station sufficiently, the rf parameters of individual cavities vary within the bunch-train. In correlation with misalignments, intrabunch-train trajectory variations are induced. An efficient model is developed to describe the effect at low beam energy, using numerically adjusted transfer matrices and discrete coupler kick coefficients, respectively. Comparison with start-to-end tracking and dedicated experiments at the FLASH injector will be shown. The short computation time of the derived model allows for comprehensive numerical studies on the impact of misalignments and variable rf parameters on the transverse intrabunch-train beam stability at the injector module. Results from both, statistical multibunch performance studies and the deduction of misalignments from multibunch experiments are presented.

Efficient model for low-energy transverse beam dynamics in a nine-cell 1.3 GHz cavity

Energy Technology Data Exchange (ETDEWEB)

Hellert, Thorsten; Dohlus, Martin; Decking, Winfried

2017-10-15

FLASH and the European XFEL are SASE-FEL user facilities, at which superconducting TESLA cavities are operated in a pulsed mode to accelerate long bunch-trains. Several cavities are powered by one klystron. While the low-level rf system is able to stabilize the vector sum of the accelerating gradient of one rf station sufficiently, the rf parameters of individual cavities vary within the bunch-train. In correlation with misalignments, intrabunch-train trajectory variations are induced. An efficient model is developed to describe the effect at low beam energy, using numerically adjusted transfer matrices and discrete coupler kick coefficients, respectively. Comparison with start-to-end tracking and dedicated experiments at the FLASH injector will be shown. The short computation time of the derived model allows for comprehensive numerical studies on the impact of misalignments and variable rf parameters on the transverse intrabunch-train beam stability at the injector module. Results from both, statistical multibunch performance studies and the deduction of misalignments from multibunch experiments are presented.

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

3D multiphysics modeling of superconducting cavities with a massively parallel simulation suite

Directory of Open Access Journals (Sweden)

Oleksiy Kononenko

2017-10-01

Full Text Available Radiofrequency cavities based on superconducting technology are widely used in particle accelerators for various applications. The cavities usually have high quality factors and hence narrow bandwidths, so the field stability is sensitive to detuning from the Lorentz force and external loads, including vibrations and helium pressure variations. If not properly controlled, the detuning can result in a serious performance degradation of a superconducting accelerator, so an understanding of the underlying detuning mechanisms can be very helpful. Recent advances in the simulation suite ace3p have enabled realistic multiphysics characterization of such complex accelerator systems on supercomputers. In this paper, we present the new capabilities in ace3p for large-scale 3D multiphysics modeling of superconducting cavities, in particular, a parallel eigensolver for determining mechanical resonances, a parallel harmonic response solver to calculate the response of a cavity to external vibrations, and a numerical procedure to decompose mechanical loads, such as from the Lorentz force or piezoactuators, into the corresponding mechanical modes. These capabilities have been used to do an extensive rf-mechanical analysis of dressed TESLA-type superconducting cavities. The simulation results and their implications for the operational stability of the Linac Coherent Light Source-II are discussed.

Simulations of the Static Tuning for the TESLA Linear Collider

CERN Document Server

Schulte, Daniel

2003-01-01

At the heart of the TESLA linear collider are the two 10 km long superconducting linacs. A linac is constructed from 858 cryomodules each containing 12 nine-cell 1.3 GHz superconducting cavities. 355 quadrupoles provide the necessary beam focusing. The advantages of low-frequency superconducting RF in terms of wakefield behaviour are well known, and the TESLA alignment tolerances are relatively loose. However, the effects of cavity tilts and their impact of the linac beam-based alignment algorithms have until recently not been fully investigated. In addition, the strong sensitivity to correlated emittance growth due to the high beam-beam disruption parameter makes it desirable to control the linac emittance down to a few percent. In this report we discuss various static tuning algorithms and present new simulation results. Discussions of the relative merits and applicability of the methods is also discussed.

The TESLA physics program

CERN Document Server

Behnke, T

2002-01-01

The TESLA accelerator concept is based on superconducting cavities, which are operated at comparatively low frequencies (L-Band, 1.3 GHz) . Superconducting cavities in connection with the low frequency offer a number of significant advantages. Because the power dissipation in the superconducting cavity walls is very small, the accelerating field can be produced with long, low peak-power RF pulses. Thus the total power consumption of the accelerator can be kept at an acceptable limit, while still maintaining a high current and a long bunch train in the machine. In fact it is possible to use a long RF pulse (of 1 ms length) and large inter-bunch spacing within one pulse (337 ns at E/sub cms/ = 500 GeV). This allows collisions with zero- crossing angle at the experiment, and gives enough time between two bunches to operate a fast feedback system to maintain stable collisions. Even more important, the relatively low RF frequency results in significant smaller wake field effects than at machine operating at larger...

Technical challenges of superconductivity and cryogenics in pursuing TESLA-TTF

International Nuclear Information System (INIS)

Shu, Quan-Sheng

1996-01-01

TESLA (TeV Energy Superconducting Linear Accelerator) Collaboration is an international R ampersand D effort towards the development of an e + e - linear collider with 500 GeV center of mass by means of 20 km active superconducting accelerating structures at a frequency of 1.3 GHz. The ultimate challenges faced by the TESLA project are (1) to raise operational accelerating gradients to 25 MV/m from current world level of 5-10 MV/m, and (2) to reduce construction costs (cryomodules, klystrons, etc.) down to $2,000/MV from now about $40,000/MV. The TESLA Collaboration is building a prototype TESLA test facility (TTF) of a 500 MeV superconducting linear accelerator to establish the technical basis. TTF is presently under construction and will be commissioned at DESY in 1997, through the joint efforts of 24 laboratories from 8 countries. Significant progress has been made in reaching the high accelerating gradient of 25 MV/m in superconducting cavities, developing cryomodules and constructing TTF infrastructure, etc. This paper will briefly discuss the challenges being faced and review the progress achieved in the technical area of superconductivity and cryogenics by the TESLA Collaboration

Superconducting cavity driving with FPGA controller

Energy Technology Data Exchange (ETDEWEB)

Czarski, T.; Koprek, W.; Pozniak, K.T.; Romaniuk, R.S. [Warsaw Univ. of Technology (Poland); Simrock, S.; Brand, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Chase, B.; Carcagno, R.; Cancelo, G. [Fermi National Accelerator Lab., Batavia, IL (United States); Koeth, T.W. [Rutgers - the State Univ. of New Jersey, NJ (United States)

2006-07-01

The digital control of several superconducting cavities for a linear accelerator is presented. The laboratory setup of the CHECHIA cavity and ACC1 module of the VU-FEL TTF in DESY-Hamburg have both been driven by a Field Programmable Gate Array (FPGA) based system. Additionally, a single 9-cell TESLA Superconducting cavity of the FNPL Photo Injector at FERMILAB has been remotely controlled from WUT-ISE laboratory with the support of the DESY team using the same FPGA control system. These experiments focused attention on the general recognition of the cavity features and projected control methods. An electrical model of the resonator was taken as a starting point. Calibration of the signal path is considered key in preparation for the efficient driving of a cavity. Identification of the resonator parameters has been proven to be a successful approach in achieving required performance; i.e. driving on resonance during filling and field stabilization during flattop time while requiring reasonable levels of power consumption. Feed-forward and feedback modes were successfully applied in operating the cavities. Representative results of the experiments are presented for different levels of the cavity field gradient. (orig.)

Superconducting cavity driving with FPGA controller

International Nuclear Information System (INIS)

Czarski, T.; Koprek, W.; Pozniak, K.T.; Romaniuk, R.S.; Simrock, S.; Brand, A.; Chase, B.; Carcagno, R.; Cancelo, G.; Koeth, T.W.

2006-01-01

The digital control of several superconducting cavities for a linear accelerator is presented. The laboratory setup of the CHECHIA cavity and ACC1 module of the VU-FEL TTF in DESY-Hamburg have both been driven by a Field Programmable Gate Array (FPGA) based system. Additionally, a single 9-cell TESLA Superconducting cavity of the FNPL Photo Injector at FERMILAB has been remotely controlled from WUT-ISE laboratory with the support of the DESY team using the same FPGA control system. These experiments focused attention on the general recognition of the cavity features and projected control methods. An electrical model of the resonator was taken as a starting point. Calibration of the signal path is considered key in preparation for the efficient driving of a cavity. Identification of the resonator parameters has been proven to be a successful approach in achieving required performance; i.e. driving on resonance during filling and field stabilization during flattop time while requiring reasonable levels of power consumption. Feed-forward and feedback modes were successfully applied in operating the cavities. Representative results of the experiments are presented for different levels of the cavity field gradient. (orig.)

Design of half-reentrant SRF cavities

International Nuclear Information System (INIS)

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

2006-01-01

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

Adapting TESLA technology for future cw light sources using HoBiCaT

Science.gov (United States)

Kugeler, O.; Neumann, A.; Anders, W.; Knobloch, J.

2010-07-01

The HoBiCaT facility has been set up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities in cw mode of operation and it was successfully demonstrated that TESLA pulsed technology can be used for cw mode of operation with only minor changes. Issues that were addressed comprise of elevated dynamic thermal losses in the cavity walls, necessary modifications in the cryogenics and the cavity processing, the optimum choice of operational parameters such as cavity temperature or bandwidth, the characterization of higher order modes in the cavity, and the usability of existing tuners and couplers for cw.

Simulation Model solves exact the Enigma named Generating high Voltages and high Frequencies by Tesla Coil

OpenAIRE

Simo Janjanin

2016-01-01

Simulation model of Tesla coil has been successfully completed, and has been verified the procedure and functioning. The literature and documentation for the model were taken from the rich sources, especially the copies of Tesla patents. The oscillating system‟s electrical scheme consists of the voltage supply 220/50 Hz, Fe transformer, capacitor and belonging chosen electrical components, the air gap in the primary Tesla coil (air transformer) and spark gap in the exit of the coil. The inves...

Report on the TESLA Engineering Study/Review

Energy Technology Data Exchange (ETDEWEB)

Cornuelle, John C.

2002-08-30

In March, 2001, the TESLA Collaboration published its Technical Design Report (TDR, see references and links in Appendix), the first sentence of which stated ''...TESLA (TeV-Energy Superconducting Linear Collider) (will be) a superconducting electron-positron collider of initially 500 GeV total energy, extendable to 800 GeV, and an integrated X-ray laser laboratory.'' The TDR included cost and manpower estimates for a 500 GeV e{sup +}e{sup -} collider (250 on 250 GeV) based on superconducting RF cavity technology. This was submitted as a proposal to the German government. The government asked the German Science Council to evaluate this proposal. The recommendation from this body is anticipated to be available by November 2002. The government has indicated that it will react on this recommendation by mid-2003. In June 2001, Steve Holmes, Fermilab's Associate Director for Accelerators, commissioned Helen Edwards and Peter Garbincius to organize a study of the TESLA Technical Design Report and the associated cost and manpower estimates. Since the elements and methodology used in producing the TESLA cost estimate were somewhat different from those used in preparing similar estimates for projects within the U.S., it is important to understand the similarities, differences, and equivalences between the TESLA estimate and U.S. cost estimates. In particular, the project cost estimate includes only purchased equipment, materials, and services, but not manpower from DESY or other TESLA collaborating institutions, which is listed separately. It does not include the R&D on the TESLA Test Facility (TTF) nor the costs of preparing the TDR nor the costs of performing the conceptual studies so far. The manpower for the pre-operations commissioning program (up to beam) is included in the estimate, but not the electrical power or liquid Nitrogen (for initial cooldown of the cryogenics plant). There is no inclusion of any contingency or management reserve. If

Report on the TESLA Engineering Study/Review

International Nuclear Information System (INIS)

Cornuelle, John C.

2002-01-01

In March, 2001, the TESLA Collaboration published its Technical Design Report (TDR, see references and links in Appendix), the first sentence of which stated ''...TESLA (TeV-Energy Superconducting Linear Collider) (will be) a superconducting electron-positron collider of initially 500 GeV total energy, extendable to 800 GeV, and an integrated X-ray laser laboratory.'' The TDR included cost and manpower estimates for a 500 GeV e + e - collider (250 on 250 GeV) based on superconducting RF cavity technology. This was submitted as a proposal to the German government. The government asked the German Science Council to evaluate this proposal. The recommendation from this body is anticipated to be available by November 2002. The government has indicated that it will react on this recommendation by mid-2003. In June 2001, Steve Holmes, Fermilab's Associate Director for Accelerators, commissioned Helen Edwards and Peter Garbincius to organize a study of the TESLA Technical Design Report and the associated cost and manpower estimates. Since the elements and methodology used in producing the TESLA cost estimate were somewhat different from those used in preparing similar estimates for projects within the U.S., it is important to understand the similarities, differences, and equivalences between the TESLA estimate and U.S. cost estimates. In particular, the project cost estimate includes only purchased equipment, materials, and services, but not manpower from DESY or other TESLA collaborating institutions, which is listed separately. It does not include the R and D on the TESLA Test Facility (TTF) nor the costs of preparing the TDR nor the costs of performing the conceptual studies so far. The manpower for the pre-operations commissioning program (up to beam) is included in the estimate, but not the electrical power or liquid Nitrogen (for initial cooldown of the cryogenics plant). There is no inclusion of any contingency or management reserve. If the U.S. were to become

Detuning related coupler kick variation of a superconducting nine-cell 1.3 GHz cavity

Science.gov (United States)

Hellert, Thorsten; Dohlus, Martin

2018-04-01

Superconducting TESLA-type cavities are widely used to accelerate electrons in long bunch trains, such as in high repetition rate free electron lasers. The TESLA cavity is equipped with two higher order mode couplers and a fundamental power coupler (FPC), which break the axial symmetry of the cavity. The passing electrons therefore experience axially asymmetrical coupler kicks, which depend on the transverse beam position at the couplers and the rf phase. The resulting emittance dilution has been studied in detail in the literature. However, the kick induced by the FPC depends explicitly on the ratio of the forward to the backward traveling waves at the coupler, which has received little attention. The intention of this paper is to present the concept of discrete coupler kicks with a novel approach of separating the field disturbances related to the standing wave and a reflection dependent part. Particular attention is directed to the role of the penetration depth of the FPC antenna, which determines the loaded quality factor of the cavity. The developed beam transport model is compared to dedicated experiments at FLASH and European XFEL. Both the observed transverse coupling and detuning related coupler kick variations are in good agreement with the model. Finally, the expected trajectory variations due to coupler kick variations at European XFEL are investigated and results of numerical studies are presented.

Construction of 0.15 Tesla Overhauser Enhanced MRI.

Science.gov (United States)

Tokunaga, Yuumi; Nakao, Motonao; Naganuma, Tatsuya; Ichikawa, Kazuhiro

2017-01-01

Overhauser enhanced MRI (OMRI) is one of the free radical imaging technologies and has been used in biomedical research such as for partial oxygen measurements in tumor, and redox status in acute oxidative diseases. The external magnetic field of OMRI is frequently in the range of 5-10 mTesla to ensure microwave penetration into small animals, and the S/N ratio is limited. In this study, a 0.15 Tesla OMRI was constructed and tested to improve the S/N ratio for a small sample, or skin measurement. Specification of the main magnet was as follows: 0.15 Tesla permanent magnet; gap size 160 mm; homogenous spherical volume of 80 mm in diameter. The OMRI resonator was designed based on TE 101 cavity mode and machined from a phosphorus deoxidized copper block for electron spin resonance (ESR) excitation and a solenoid transmission/receive resonator for NMR detection. The resonant frequencies and Q values were 6.38 MHz/150 and 4.31-4.41 GHz/120 for NMR and ESR, respectively. The Q values were comparable to those of conventional low field OMRI resonators at 15 mTesla. As expected, the MRI S/N ratio was improved by a factor of 30. Triplet dynamic nuclear polarization spectra were observed for 14 N carboxy-PROXYL, along the excitation microwave sweep. In the current setup, the enhancement factor was ca. 0.5. In conclusion, the results of this preliminary evaluation indicate that the 0.15 Tesla OMRI could be useful for free radical measurement for small samples.

Control System Design for Automatic Cavity Tuning Machines

Energy Technology Data Exchange (ETDEWEB)

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

2009-05-01

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

Control System Design for Automatic Cavity Tuning Machines

International Nuclear Information System (INIS)

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

2009-01-01

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

New achievements in RF cavity manufacturing

International Nuclear Information System (INIS)

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

1993-01-01

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

Geometric Model of a Coronal Cavity

Science.gov (United States)

Kucera, Therese A.; Gibson, S. E.; Ratawicki, D.; Dove, J.; deToma, G.; Hao, J.; Hudson, H. S.; Marque, C.; McIntosh, P. S.; Reeves, K. K.;

About the origin of matter - the TESLA project

International Nuclear Information System (INIS)

Heuer, R.D.

2004-01-01

An introduction to the TESLA project is given. After a general introduction to the standard model of elementary particles together with some possible extension the scientific potential of TESLA is described with special regards to the production of Higgs bosons and supersymmetric particles. Finally the technology of TESLA is considered. (HSI)

8-channel, FPGA based, DSP integrated cavity simulator and controller for VUV-FEL. SIMCON 3.0 Ver. 3.0. rev. 1, 06.2005 - Hardware manual

International Nuclear Information System (INIS)

Pozniak, K.T.; Czarski, T.; Koprek, W.; Giergusiewicz, W.; Romaniuk, R.S.

2005-01-01

The note describes integrated, eight channel system of hardware controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now tested for the VUV FEL and developed for X-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V4000. The solution uses DSP EMBEDDED BOARD module positioned on a Modular LLRF Control Platform. The algorithm and FPGA circuit configuration was done in the VHDL language. The internal hardware multiplication components, present in Virtex II chips, were used, to improve the floating point calculation efficiency. The implementation was achieved of a device working in the real time, according to the demands of the LLRF control system for the TESLA Test Facility (now associated with the VUV FEL machine). The device under consideration will be referred to as superconducting cavity (SCCav) SIMCON throughout this work. The manual describes hardware features of SIMCON, ver. 3.0 in modular solution. The following components are described here in detail: functional layer, parameter programming, foundations of control of particular blocks and monitoring of the real time processes. This note is accompanied by the one describing the multichannel DOOCS interface for the described hardware system. The interface was prepared in DOOCS for Solaris and in Windows. The hardware and software of 8-channel SIMCON was tested in CHECIA and ACC1 module of VUV FEL linac. The measurements results are presented. While giving all necessary technical details required to understand the work of the integrated hardware controller and simulator and to enable its practical copying, this document is a unity with other TESLA technical notes published by the same team on the subject. Thus, some modeling and other subjects were omitted, as they were addressed in detail in the quoted references. Keywords: Super conducting cavity, cavity simulator, CAVITIES CONTROLLER, SIMCON

Short bunch wake potentials for a chain of TESLA cavities

International Nuclear Information System (INIS)

Novokhatski, Alexander; Mosnier, Alban

2014-01-01

The modification of wake fields from a single cavity to a quasi-periodic structure of cavities is of great concern, especially for applications using very short bunches. We extend our former study (Novokhatski, 1997 [1]). A strong modification of wake fields along a train of cavities was clearly found for bunch lengths lower than 1 mm. In particular, the wakes induced by the bunch, as it proceeds down the successive cavities, decrease in amplitude and become more linear around the bunch center, with a profile very close to the integral of the charge density. The loss factor, decreasing also with the number of cells, becomes independent of bunch length for very short bunches and tends asymptotically to a finite value. This nice behavior of wake fields for short bunches presents good opportunity for application of very short bunches in Linear Colliders and X-ray Free Electron Lasers

Manual of Tesla Experiments; Handbuch Tesla Experimente

Energy Technology Data Exchange (ETDEWEB)

Wahl, Guenter

2009-07-01

The first part, ''Making Lightning and Thunder'', describes a number of Tesla generators that can generate, e.g., coloured light arcs, ball lightning and swords of lightning. The second part, ''New Experiments with EMP, Tesla Waves and Microwaves'', presents a solid state Tesla generator for generating electrodynamic vortices and proposes circuiting alternatives to generate electromagnetic pulses (EMP). Further, mysterious Teslar wave, microwave and scalar wave generators are presented, as well as exotic Star Wars experiments like mass accelerators and plasma guns. The third section describes, among others, a tube-driven Tesla generator with 50 cm streamers. The reader will also find a catalogue of Messrs. Information Unlimited, USA, who are providers of many of the kits, circuiting diagrams and apparatuses presented here. (orig.) [German] Der erste Teil mit dem Titel ''Blitz und Donner selbst erzeugt'' beschreibt eine Reihe von Teslageneratoren, mit denen zum Beispiel bunte Lichtbogen, Kugelblitze und Blitzschwerter erzeugt werden koennen. Im zweiten Teil ''Neue Experimente mit EMPs, Tesla- and Mikrowellen'' findet der Leser einen Solid-State-Teslagenerator zur Erzeugung elektrodynamischer Wirbel sowie Schaltungsvorschlaege zum Thema ''Elektromagnetischer Impuls'' (EMP). Des Weiteren werden geheimnisumwitterte Tesla-, Mikro- und Skalarwellengeneratoren vorgestellt. Exotische Star-Wars-Experimente wie Massenbeschleuniger und Plasmakanonen fehlen ebenfalls nicht. Im dritten Teil wird unter anderem ein roehrenbetriebener Teslagenerator mit Streamern von 50 cm Laenge beschrieben. Ausserdem findet der Leser hier einen Katalog der US-Firma Information Unlimited, bei der viele im Buch besprochenen Bausaetze, Schaltplaene und Fertiggeraete bezogen werden koennen. (orig.)

Business Model Design: Lessons Learned from Tesla Motors

OpenAIRE

Chen , Yurong; Perez , Yannick

2015-01-01

International audience; Electric vehicle (EV) industry is still in the introduction stage in product life cycle, and dominant design remains unclear. EV companies, both incumbent from the car industry and new comers, have long taken numerous endeavors to promote EV in the niche market by providing innovative products and business models. While most carmakers still take 'business as usual' approach for developing their EV production and offers, Tesla Motors, an EV entrepreneurial firm, stands ...

Study and development of an input coupler for the future TESLA collider

International Nuclear Information System (INIS)

Dupery, C.

1996-01-01

The TESLA (TeV Superconducting Linear Accelerator) is operating with a high frequency cavity resonator input coupler. Some technical restraints (such as thermal, mechanical, electrical, vacuum, multipactor discharge phenomena) constrain the development of this coupler. In order to solve these problems, studies have been performed at the French Atomic Energy Commission (CEA) and are presented in this paper

Experimental program with beam in TESLA test facility

International Nuclear Information System (INIS)

Mosnier, A.; Aune, B.

1994-09-01

In order to establish a technical basis for a high energy e + e - collider using the superconducting RF technology, the test of a string of 32 cavities with beam at an accelerating gradient of 15 MV/m is planned in an installation at DESY. Several experiments with beam in the TTF linac will be performed. The dissipated HOM power at helium temperature is a key issue for TESLA, its estimation requires careful calorimetric measurements and the full charge injector. Bunch wake potentials can be estimated with bunch charges of at least 1 to 2 nC. Multibunch measurements require a beam of a few hundreds of these bunches. The beam will be injected either on axis or off axis. RF steering due to couplers will be estimated by measuring the beam displacement for different RF phase settings. The expected resolution is well below the TESLA specification. The acceleration of dark currents will be observed for different settings of the focusing elements. 7 figs., 1 tab., 3 refs

Large-Signal Code TESLA: Improvements in the Implementation and in the Model

National Research Council Canada - National Science Library

Chernyavskiy, Igor A; Vlasov, Alexander N; Anderson, Jr., Thomas M; Cooke, Simon J; Levush, Baruch; Nguyen, Khanh T

2006-01-01

We describe the latest improvements made in the large-signal code TESLA, which include transformation of the code to a Fortran-90/95 version with dynamical memory allocation and extension of the model...

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography—An in vivo and in vitro study

Energy Technology Data Exchange (ETDEWEB)

Schaafsma, Joanna D., E-mail: j.d.schaafsma@umcutrecht.nl [Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Velthuis, Birgitta K., E-mail: b.k.velthuis@umcutrecht.nl [Imaging Division, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Vincken, Koen L., E-mail: koen@isi.uu.nl [Image Sciences Institute, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Kort, Gerard A.P. de, E-mail: g.a.p.dekort@umcutrecht.nl [Imaging Division, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Rinkel, Gabriel J.E., E-mail: g.j.e.rinkel@umcutrecht.nl [Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands); Bartels, Lambertus W., E-mail: w.bartels@umcutrecht.nl [Image Sciences Institute, University Medical Centre, PO Box 85500, 3508 GA Utrecht (Netherlands)

2014-05-15

Objective: To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0 Tesla. Materials and methods: We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0 Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0 Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Results: Coil artefacts disturbed assessments less frequently at 3.0 Tesla than at 1.5 Tesla (RR: 0.3; 95%CI: 0.1–0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7 mm; 95%CI: 0.3–1.1) and larger than on IA-DSA (difference: 1.0 mm; 95%CI: 0.6–1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23–0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19–0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0 Tesla than at 1.5 Tesla. The echo-time influenced artefact size more than the read-out gradient. Conclusions: Artefacts were not larger, but smaller at 3.0 Tesla because a shorter echo-time at 3.0 Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0 Tesla, occlusion levels were similar for both field strengths.

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography—An in vivo and in vitro study

International Nuclear Information System (INIS)

Schaafsma, Joanna D.; Velthuis, Birgitta K.; Vincken, Koen L.; Kort, Gerard A.P. de; Rinkel, Gabriel J.E.; Bartels, Lambertus W.

2014-01-01

Objective: To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0 Tesla. Materials and methods: We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0 Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0 Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Results: Coil artefacts disturbed assessments less frequently at 3.0 Tesla than at 1.5 Tesla (RR: 0.3; 95%CI: 0.1–0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7 mm; 95%CI: 0.3–1.1) and larger than on IA-DSA (difference: 1.0 mm; 95%CI: 0.6–1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23–0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19–0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0 Tesla than at 1.5 Tesla. The echo-time influenced artefact size more than the read-out gradient. Conclusions: Artefacts were not larger, but smaller at 3.0 Tesla because a shorter echo-time at 3.0 Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0 Tesla, occlusion levels were similar for both field strengths

Artefacts induced by coiled intracranial aneurysms on 3.0-Tesla versus 1.5-Tesla MR angiography--An in vivo and in vitro study.

Science.gov (United States)

Schaafsma, Joanna D; Velthuis, Birgitta K; Vincken, Koen L; de Kort, Gerard A P; Rinkel, Gabriel J E; Bartels, Lambertus W

2014-05-01

To compare metal-induced artefacts from coiled intracranial aneurysms on 3.0-Tesla and 1.5-Tesla magnetic resonance angiography (MRA), since concerns persist on artefact enlargement at 3.0Tesla. We scanned 19 patients (mean age 53; 16 women) with 20 saccular aneurysms treated with coils only, at 1.5 and 3.0Tesla according to standard clinical 3D TOF-MRA protocols containing a shorter echo-time but weaker read-out gradient at 3.0Tesla in addition to intra-arterial digital subtraction angiography (IA-DSA). Per modality two neuro-radiologists assessed the occlusion status, measured residual flow, and indicated whether coil artefacts disturbed this assessment on MRA. We assessed relative risks for disturbance by coil artefacts, weighted kappa's for agreement on occlusion levels, and we compared remnant sizes. For artefact measurements, a coil model was created and scanned with the same protocols followed by 2D MR scans with variation of echo-time and read-out gradient strength. Coil artefacts disturbed assessments less frequently at 3.0Tesla than at 1.5Tesla (RR: 0.3; 95%CI: 0.1-0.8). On 3.0-Tesla MRA, remnants were larger than on 1.5-Tesla MRA (difference: 0.7mm; 95%CI: 0.3-1.1) and larger than on IA-DSA (difference: 1.0mm; 95%CI: 0.6-1.5) with similar agreement on occlusion levels with IA-DSA for both field strengths (κ 0.53; 95%CI: 0.23-0.84 for 1.5-Tesla MRA and IA-DSA; κ 0.47; 95%CI: 0.19-0.76 for 3.0-Tesla MRA and IA-DSA). Coil model artefacts were smaller at 3.0Tesla than at 1.5Tesla. The echo-time influenced artefact size more than the read-out gradient. Artefacts were not larger, but smaller at 3.0Tesla because a shorter echo-time at 3.0Tesla negated artefact enlargement. Despite smaller artefacts and larger remnants at 3.0Tesla, occlusion levels were similar for both field strengths. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Forward Modeling of a Coronal Cavity

Science.gov (United States)

Kucera, T. A.; Gibson, S. E.; Schmit, D. J.

2011-01-01

We apply a forward model of emission from a coronal cavity in an effort to determine the temperature and density distribution in the cavity. Coronal cavities are long, low-density structures located over filament neutral lines and are often seen as dark elliptical features at the solar limb in white light, EUV and X-rays. When these structures erupt they form the cavity portions of CMEs The model consists of a coronal streamer model with a tunnel-like cavity with elliptical cross-section and a Gaussian variation of height along the tunnel length. Temperature and density can be varied as a function of altitude both in the cavity and streamer. We apply this model to a cavity observed in Aug. 2007 by a wide array of instruments including Hinode/EIS, STEREO/EUVI and SOHO/EIT. Studies such as these will ultimately help us understand the the original structures which erupt to become CMEs and ICMES, one of the prime Solar Orbiter objectives.

Non-enhanced MR imaging of cerebral aneurysms: 7 Tesla versus 1.5 Tesla.

Science.gov (United States)

Wrede, Karsten H; Dammann, Philipp; Mönninghoff, Christoph; Johst, Sören; Maderwald, Stefan; Sandalcioglu, I Erol; Müller, Oliver; Özkan, Neriman; Ladd, Mark E; Forsting, Michael; Schlamann, Marc U; Sure, Ulrich; Umutlu, Lale

2014-01-01

To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA). Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin's concordance correlation coefficient. A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings. 7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high-quality diagnostic tool for pretherapeutic assessment and

Use of the upper radial order modes in spherical superconducting cavities

International Nuclear Information System (INIS)

Reuss, J.

1975-04-01

Spherical cavities resonating on a high g radial order mode are considered. The ratio of the maximum magnetic field inside the cavity to the maximum field on the wall is proportional to g. The proportion coefficient is given for the TEsub(g10); TEsub(g20), TMsub(g10), and TMsub(g20) modes. That corresponds to an energy concentration at the center. Owing to this property the superconducting cavities might be used to produce strong H.F. magnetic fields (larger than 10 Teslas) [fr

Contamination issues in superconducting cavity technology

International Nuclear Information System (INIS)

Kneisel, Peter

1997-01-01

The application of radio-frequency superconductivity technology in particle accelerator projects has become increasingly evident in recent years. Several large scale projects around the world are either completed or close to completion, such as CEBAF, HERA, TRISTAN and LEP. And superconducting cavity technology is seriously being considered for future applications in linear colliders (TESLA), high current proton accelerators (APT, spallation neutron sources), muon colliders and free electron lasers for industrial application. The reason for this multitude of activities are matured technology based on a better understanding of the phenomena encountered in superconducting cavities and the influence of improved material properties and contamination and quality control measures

Field stabilization in superconducting cavities under pulsed operating

International Nuclear Information System (INIS)

Tessier, J.M.

1996-01-01

Within the framework of Tesla linear accelerator project, superconducting cavity battery is used to accelerate electrons and positrons. These cavities require pulsed running and must reach very high accelerating gradients. Under the action of the Lorentz force, the resonance frequency shifts and leaves the band-pass width, which hinders the field from taking its maximal value inside the cavity. The setting of an auto-oscillating loop allows to bring the generator frequency under the control of the cavity frequency. A feedback system is needed to reduce the energy dispersion inside the particle packets. The effects of the mechanical vibrations that disturb the accelerating voltage phase between two impulses are also compensated by a feedback loop. This thesis describes all these phenomena and computes their effects on the energy dispersion of the beam in both cases of relativistic and non-relativistic particles. (A.C.)

Nell’anno di Nikola Tesla

Directory of Open Access Journals (Sweden)

Persida Lazarević Di Giacomo

2006-12-01

Full Text Available The 150th Anniversary Celebration of Nikola Tesla The paper deals with the 150th anniversary celebration of Nikola Tesla, the greatest ever Yugoslav scientist. Due to his origins, Tesla is contended between Serbia and Croatia, but he is also considered to be an American scientist since he registered most of his patents in the USA. Although there is some dissension between Serbia and Croatia regarding the historical facts about Tesla’s life, it can be asserted that Tesla appears to be an example of collaboration among the former Yugoslav countries. Tesla, however, deserves to be remembered as well as the author of autobiographical prose (My Inventions; Some Personal Recollections; A Strange Experience by Nikola Tesla and as the protagonist of many works published in Serbo-Croatian and in English, such as Miloš Crnjanski’s drama Tesla (1969 or The Hunger and Ecstasy of Vampires (1996 by Brian M. Stableford, for example. This fact should not be neglected and actually should be researched more fully.

[70 years of Nikola Tesla studies].

Science.gov (United States)

Juznic, Stanislav

2013-01-01

Nikola Tesla's studies of chemistry are described including his not very scholarly affair in Maribor. After almost a century and half of hypothesis at least usable scenario of Tesla's life and "work" in Maribor is provided. The chemistry achievements of Tesla's most influential professors Martin Sekulić and Tesla's Graz professors are put into the limelight. The fact that Tesla in Graz studied on the technological chemistry Faculty of Polytechnic is focused.

Tissue expander stimulated lengthening of arteries (TESLA) induces early endothelial cell proliferation in a novel rodent model.

Science.gov (United States)

Potanos, Kristina; Fullington, Nora; Cauley, Ryan; Purcell, Patricia; Zurakowski, David; Fishman, Steven; Vakili, Khashayar; Kim, Heung Bae

2016-04-01

We examine the mechanism of aortic lengthening in a novel rodent model of tissue expander stimulated lengthening of arteries (TESLA). A rat model of TESLA was examined with a single stretch stimulus applied at the time of tissue expander insertion with evaluation of the aorta at 2, 4 and 7day time points. Measurements as well as histology and proliferation assays were performed and compared to sham controls. The aortic length was increased at all time points without histologic signs of tissue injury. Nuclear density remained unchanged despite the increase in length suggesting cellular hyperplasia. Cellular proliferation was confirmed in endothelial cell layer by Ki-67 stain. Aortic lengthening may be achieved using TESLA. The increase in aortic length can be achieved without tissue injury and results at least partially from cellular hyperplasia. Further studies are required to define the mechanisms involved in the growth of arteries under increased longitudinal stress. Copyright © 2015 Elsevier Inc. All rights reserved.

Offline estimation of decay time for an optical cavity with a low pass filter cavity model.

Science.gov (United States)

Kallapur, Abhijit G; Boyson, Toby K; Petersen, Ian R; Harb, Charles C

2012-08-01

This Letter presents offline estimation results for the decay-time constant for an experimental Fabry-Perot optical cavity for cavity ring-down spectroscopy (CRDS). The cavity dynamics are modeled in terms of a low pass filter (LPF) with unity DC gain. This model is used by an extended Kalman filter (EKF) along with the recorded light intensity at the output of the cavity in order to estimate the decay-time constant. The estimation results using the LPF cavity model are compared to those obtained using the quadrature model for the cavity presented in previous work by Kallapur et al. The estimation process derived using the LPF model comprises two states as opposed to three states in the quadrature model. When considering the EKF, this means propagating two states and a (2×2) covariance matrix using the LPF model, as opposed to propagating three states and a (3×3) covariance matrix using the quadrature model. This gives the former model a computational advantage over the latter and leads to faster execution times for the corresponding EKF. It is shown in this Letter that the LPF model for the cavity with two filter states is computationally more efficient, converges faster, and is hence a more suitable method than the three-state quadrature model presented in previous work for real-time estimation of the decay-time constant for the cavity.

Nell’anno di Nikola Tesla

OpenAIRE

Persida Lazarević Di Giacomo

2006-01-01

The 150th Anniversary Celebration of Nikola Tesla The paper deals with the 150th anniversary celebration of Nikola Tesla, the greatest ever Yugoslav scientist. Due to his origins, Tesla is contended between Serbia and Croatia, but he is also considered to be an American scientist since he registered most of his patents in the USA. Although there is some dissension between Serbia and Croatia regarding the historical facts about Tesla’s life, it can be asserted that Tesla appears to be an...

In-house L-band niobium single cell cavities at KEK

International Nuclear Information System (INIS)

Inoue, Hitoshi; Kobayashi, Yoshiharu; Funahashi, Yoshisato; Koizumi, Susumu; Saito, Kenji; Noguchi, Shuichi; Kako, Eiji; Shishido, Toshio

1993-01-01

For the TESLA (TeV Energy Superconducting Linear Accelerator) as an energy frontier accelerator of the next generation improving the performance of the niobium superconducting cavities is the most important issue and much reduction of fabrication cost of cavities is another key. Since manufacturing of niobium material requires hard techniques due to the easily oxidizable metal, fabrication of niobium cavities has been conducted in only companies providing enough equipments in Japan. KEK has accumulated the fabrication technics such as forming method by deep drawing, trimming, centering of beam tubes, electron beam welding and measurement of manufacturing error so on. We made in-house L-band single cell cavities using these technologies. In this paper we present these manufacturing of the niobium cavities and estimate the fabrication cost as exactly as possible. The manufacturing error is also described. (author)

k-t SENSE-accelerated Myocardial Perfusion MR Imaging at 3.0 Tesla - comparison with 1.5 Tesla

Science.gov (United States)

Plein, Sven; Schwitter, Juerg; Suerder, Daniel; Greenwood, John P.; Boesiger, Peter; Kozerke, Sebastian

2008-01-01

Purpose To determine the feasibility and diagnostic accuracy of high spatial resolution myocardial perfusion MR at 3.0 Tesla using k-space and time domain undersampling with sensitivity encoding (k-t SENSE). Materials and Methods The study was reviewed and approved by the local ethic review board. k-t SENSE perfusion MR was performed at 1.5 Tesla and 3.0 Tesla (saturation recovery gradient echo pulse sequence, repetition time/echo time 3.0ms/1.0ms, flip angle 15°, 5x k-t SENSE acceleration, spatial resolution 1.3×1.3×10mm3). Fourteen volunteers were studied at rest and 37 patients during adenosine stress. In volunteers, comparison was also made with standard-resolution (2.5×2.5×10mm3) 2x SENSE perfusion MR at 3.0 Tesla. Image quality, artifact scores, signal-to-noise ratios (SNR) and contrast-enhancement ratios (CER) were derived. In patients, diagnostic accuracy of visual analysis to detect >50% diameter stenosis on quantitative coronary angiography was determined by receiver-operator-characteristics (ROC). Results In volunteers, image quality and artifact scores were similar for 3.0 Tesla and 1.5 Tesla, while SNR was higher (11.6 vs. 5.6) and CER lower (1.1 vs. 1.5, p=0.012) at 3.0 Tesla. Compared with standard-resolution perfusion MR, image quality was higher for k-t SENSE (3.6 vs. 3.1, p=0.04), endocardial dark rim artifacts were reduced (artifact thickness 1.6mm vs. 2.4mm, pTesla and 1.5 Tesla, respectively. Conclusions k-t SENSE accelerated high-resolution perfusion MR at 3.0 Tesla is feasible with similar artifacts and diagnostic accuracy as at 1.5 Tesla. Compared with standard-resolution perfusion MR, image quality is improved and artifacts are reduced. PMID:18936311

Intraindividual comparison of image quality in MR urography at 1.5 and 3 Tesla in an animal model

Energy Technology Data Exchange (ETDEWEB)

Regier, M.; Adam, G.; Kemper, J. [Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Hamburg-Eppendorf (Germany); Nolte-Ernsting, C. [Klinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Hamburg-Eppendorf (Germany)

2008-10-15

Purpose: experimental evaluation of image quality of the upper urinary tract in MR urography (MRU) at 1.5 and 3 Tesla in a porcine model. Materials and methods: in this study four healthy domestic pigs, weighing between 71 and 80 kg (mean 73.6 kg), were examined with a standard T 1w 3D-GRE and a high-resolution (HR) T 1w 3D-GRE sequence at 1.5 and 3 Tesla. Additionally, at 3 Tesla both sequences were performed with parallel imaging (SENSE factor 2). The MR urographic scans were performed after intravenous injection of gadolinium-DTPA (0.1 mmol/kg body weight (bw)) and low-dose furosemide (0.1 mg/kg bw). Image evaluation was performed by two independent radiologists blinded to sequence parameters and field strength. Image analysis included grading of image quality of the segmented collecting system based on a five-point grading scale regarding anatomical depiction and artifacts observed (1: the majority of the segment (> 50%) was not depicted or was obscured by major artifacts; 5: the segment was visualized without artifacts and had sharply defined borders). Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were determined. Statistical analysis included {kappa}-statistics, Wilcoxon and paired student t-test. Results: the mean scores for MR urographies at 1.5 Tesla were 2.83 for the 3D-GRE and 3.48 for the HR 3D-GRE sequence. Significantly higher values were determined using the corresponding sequences at 3 Tesla, averaging 3.19 for the 3D-GRE (p = 0.047) and 3.92 for the HR 3D-GRE (p = 0.023) sequence. Delineation of the pelvicaliceal system was rated significantly higher at 3 Tesla compared to 1.5 Tesla (3D-GRE: p = 0.015; HR 3D-GRE: p = 0.006). At 3 Tesla the mean SNR and CNR were significantly higher (p < 0.05). A {kappa} of 0.67 indicated good interobserver agreement. (orig.)

Intraindividual comparison of image quality in MR urography at 1.5 and 3 Tesla in an animal model

International Nuclear Information System (INIS)

Regier, M.; Adam, G.; Kemper, J.; Nolte-Ernsting, C.

2008-01-01

Purpose: experimental evaluation of image quality of the upper urinary tract in MR urography (MRU) at 1.5 and 3 Tesla in a porcine model. Materials and methods: in this study four healthy domestic pigs, weighing between 71 and 80 kg (mean 73.6 kg), were examined with a standard T 1w 3D-GRE and a high-resolution (HR) T 1w 3D-GRE sequence at 1.5 and 3 Tesla. Additionally, at 3 Tesla both sequences were performed with parallel imaging (SENSE factor 2). The MR urographic scans were performed after intravenous injection of gadolinium-DTPA (0.1 mmol/kg body weight (bw)) and low-dose furosemide (0.1 mg/kg bw). Image evaluation was performed by two independent radiologists blinded to sequence parameters and field strength. Image analysis included grading of image quality of the segmented collecting system based on a five-point grading scale regarding anatomical depiction and artifacts observed (1: the majority of the segment (> 50%) was not depicted or was obscured by major artifacts; 5: the segment was visualized without artifacts and had sharply defined borders). Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were determined. Statistical analysis included κ-statistics, Wilcoxon and paired student t-test. Results: the mean scores for MR urographies at 1.5 Tesla were 2.83 for the 3D-GRE and 3.48 for the HR 3D-GRE sequence. Significantly higher values were determined using the corresponding sequences at 3 Tesla, averaging 3.19 for the 3D-GRE (p 0.047) and 3.92 for the HR 3D-GRE (p = 0.023) sequence. Delineation of the pelvicaliceal system was rated significantly higher at 3 Tesla compared to 1.5 Tesla (3D-GRE: p = 0.015; HR 3D-GRE: p = 0.006). At 3 Tesla the mean SNR and CNR were significantly higher (p < 0.05). A κ of 0.67 indicated good interobserver agreement. (orig.)

The Grenoble station for producing strong transient magnetic fields higher than 100 teslas by an explosive driven flux compression

International Nuclear Information System (INIS)

Guillot, M.

1976-01-01

Reproducible transient magnetic fields up to 400 teslas (4 megaoersted) are achieved by a simple explosive driven flux compression. The results are described simply from the point of view of energy conversion. The problems of field measurements are studied: the precision is +-2% with a field cavity of 5 mm diameter [fr

TESLA project goes public

International Nuclear Information System (INIS)

Flegel', I.

2002-01-01

The TESLA project connected with the creation of superconducting linear accelerator with colliding neutron and positron beams in the DESY Laboratory (Hamburg) is presented. Scientists of 36 countries make a contribution in the Feasibility study of new accelerator construction. Creation of new accelerator will open the way to the investigation into new elementary particles; TESLA is perfectly suitable for the production of Higgs particles. Exact measurements on the unit will allow to research into properties of supersymmetrical particles. The TESLA project involves the creation of X-ray free electron laser [ru

Modeling Coupled Evaporation and Seepage in Ventilated Cavities

International Nuclear Information System (INIS)

Ghezzehei, T.; Trautz, R.; Finsterle, S.; Cook, P.; Ahlers, C.

2004-01-01

Cavities excavated in unsaturated geological formations are important to activities such as nuclear waste disposal and mining. Such cavities provide a unique setting for simultaneous occurrence of seepage and evaporation. Previously, inverse numerical modeling of field liquid-release tests and associated seepage into cavities were used to provide seepage-related large-scale formation properties by ignoring the impact of evaporation. The applicability of such models was limited to the narrow range of ventilation conditions under which the models were calibrated. The objective of this study was to alleviate this limitation by incorporating evaporation into the seepage models. We modeled evaporation as an isothermal vapor diffusion process. The semi-physical model accounts for the relative humidity, temperature, and ventilation conditions of the cavities. The evaporation boundary layer thickness (BLT) over which diffusion occurs was estimated by calibration against free-water evaporation data collected inside the experimental cavities. The estimated values of BLT were 5 to 7 mm for the open underground drifts and 20 mm for niches closed off by bulkheads. Compared to previous models that neglected the effect of evaporation, this new approach showed significant improvement in capturing seepage fluctuations into open cavities of low relative humidity. At high relative-humidity values (greater than 85%), the effect of evaporation on seepage was very small

Thermal Model of a Dish Stirling Cavity-Receiver

Directory of Open Access Journals (Sweden)

Rubén Gil

2015-01-01

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

DOOCS environment for FPGA-based cavity control system and control algorithms development

International Nuclear Information System (INIS)

Pucyk, P.; Koprek, W.; Kaleta, P.; Szewinski, J.; Pozniak, K.T.; Czarski, T.; Romaniuk, R.S.

2005-01-01

The paper describes the concept and realization of the DOOCS control software for FPGAbased TESLA cavity controller and simulator (SIMCON). It bases on universal software components, created for laboratory purposes and used in MATLAB based control environment. These modules have been recently adapted to the DOOCS environment to ensure a unified software to hardware communication model. The presented solution can be also used as a general platform for control algorithms development. The proposed interfaces between MATLAB and DOOCS modules allow to check the developed algorithm in the operation environment before implementation in the FPGA. As the examples two systems have been presented. (orig.)

Nikola Tesla: een biografie

NARCIS (Netherlands)

ir.ing. Ruud Thelosen

2015-01-01

De Technische uitvinder Tesla heeft 700 patenten op zijn naam staan als hij overlijdt. Zijn uitvindingen hebben de wereld in de 20e eeuw volledig veranderd. Zijn wisselstroom generator hebben heel de VS van elektriciteit voorzien. Radioverkeer , remote control werd mogelijk dankzij Tesla. Volgens

Measurement of Microwave Parameters of a Superconducting Niobium Cavity

Science.gov (United States)

Azaryan, N. S.; Baturitskii, M. A.; Budagov, Yu. A.; Demin, D. L.; Dem‧yanov, S. E.; Karpovich, V. A.; Kniga, V. V.; Krivosheev, R. M.; Lyubetskii, N. V.; Maksimov, S. I.; Pobol‧, I. L.; Rodionova, V. N.; Shirkov, G. D.; Shumeiko, N. M.; Yurevich, S. V.

2017-01-01

This paper describes a method for direct measurement of the amplitude-frequency characteristics and the Q factor of empty superconducting niobium radio frequency Tesla-type cavities. An automated measuring complex that permits recording the superconductivity effect and measuring high Q values has been developed. Measurements have been made of the Q factors of the investigated objects (the first domestic 1.3-GHz niobium cavities) at a level no lower than 0.1·109 (with a maximum value of 1.2·1010) and a level of relative losses lower than 130 dB (with a minimum factor of 139.7 dB) at liquid nitrogen temperature.

Hydroforming SRF Three-cell Cavity from Seamless Niobium Tube

Energy Technology Data Exchange (ETDEWEB)

Yamanaka, Masashi [KEK, Tsukuba; Dohmae, Takeshi [KEK, Tsukuba; Hocker, Andy [Fermilab; Inoue, Hitoshi [KEK, Tsukuba; Park, Gunn-Tae [KEK, Tsukuba; Tajima, Tsuyoshi [Los Alamos; Umemori, Kensei [KEK, Tsukuba

2016-06-01

We are developing the manufacturing method for superconducting radio frequency (SRF) cavities by using a hydroforming instead of using conventional electron beam welding. We expect higher reliability and reduced cost with hydroforming. For successful hydroforming, high-purity seamless niobium tubes with good formability as well as advancing the hydroforming technique are necessary. Using a seamless niobium tube from ATI Wah Chang, we were able to successfully hydroform a 1.3 GHz three-cell TESLA-like cavity and obtained an Eacc of 32 MV/m. A barrel polishing process was omitted after the hydroforming. The vertical test was carried out with very rough inside surface. We got amazing and interesting result.

Effects of cavity-cavity interaction on the entanglement dynamics of a generalized double Jaynes-Cummings model

Science.gov (United States)

Pandit, Mahasweta; Das, Sreetama; Singha Roy, Sudipto; Shekhar Dhar, Himadri; Sen, Ujjwal

2018-02-01

We consider a generalized double Jaynes-Cummings model consisting of two isolated two-level atoms, each contained in a lossless cavity that interact with each other through a controlled photon-hopping mechanism. We analytically show that at low values of such a mediated cavity-cavity interaction, the temporal evolution of entanglement between the atoms, under the effects of cavity perturbation, exhibits the well-known phenomenon of entanglement sudden death (ESD). Interestingly, for moderately large interaction values, a complete preclusion of ESD is achieved, irrespective of its value in the initial atomic state. Our results provide a model to sustain entanglement between two atomic qubits, under the adverse effect of cavity induced perturbation, by introducing a non-intrusive inter-cavity photon exchange that can be physically realized through cavity-QED setups in contemporary experiments.

Tuning of External Q And Phase for The Cavities of A Superconducting Linear Accelerator

CERN Document Server

Katalev, V V

2004-01-01

The RF power required for a certain gradient of a superconducting cavity depends on the beam current and coupling between the cavity and waveguide. The coupling with the cavity may be changed by variation of Qext. Different devices can be used to adjust Qext or phase. In this paper three stub and E-H tuners are compared and their usability for the RF power distribution system for the superconducting accelerator of the European Xray laser and the TESLA linear collider is considered. The tuners were analyzed by using the scattering matrix. Advantages and limitations of the devices are presented.

Performance estimation of Tesla turbine applied in small scale Organic Rankine Cycle (ORC) system

International Nuclear Information System (INIS)

Song, Jian; Gu, Chun-wei; Li, Xue-song

2017-01-01

Highlights: • One-dimensional model of the Tesla turbine is improved and applied in ORC system. • Working fluid properties and system operating conditions impact efficiency. • The influence of turbine efficiency on ORC system performance is evaluated. • Potential of using Tesla turbine in ORC systems is estimated. - Abstract: Organic Rankine Cycle (ORC) system has been proven to be an effective method for the low grade energy utilization. In small scale applications, the Tesla turbine offers an attractive option for the organic expander if an efficient design can be achieved. The Tesla turbine is simple in structure and is easy to be manufactured. This paper improves the one-dimensional model for the Tesla turbine, which adopts a non-dimensional formulation that identifies the dimensionless parameters that dictates the performance features of the turbine. The model is used to predict the efficiency of a Tesla turbine that is applied in a small scale ORC system. The influence of the working fluid properties and the operating conditions on the turbine performance is evaluated. Thermodynamic analysis of the ORC system with different organic working fluids and under various operating conditions is conducted. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, the Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

Tesla - A Flash of a Genius

Science.gov (United States)

Teodorani, M.

2005-10-01

This book, which is entirely dedicated to the inventions of scientist Nikola Tesla, is divided into three parts: a) all the most important innovative technological creations from the alternate current to the death ray, Tesla research in fundamental physics with a particular attention to the concept of "ether", ball lightning physics; b) the life and the bright mind of Nikola Tesla and the reasons why some of his most recent findings were not accepted by the establishment; c) a critical discussion of the most important work by Tesla followers.

A Study of Thermocurrent Induced Magnetic Fields in ILC Cavities

Energy Technology Data Exchange (ETDEWEB)

Crawford, Anthony C. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Cooley, Victoria [Univ. of Wisconsin, Madison, WI (United States)

2014-03-31

The case of axisymmetric ILC-type cavities with titanium helium vessels is investigated. A first-order estimate for magnetic field within the SRF current layer is presented. The induced magnetic field is found to be not more than 1.4x10^-8 Tesla = 0.14 milligauss for the case of axial symmetry. Magnetic fields due to symmetry breaking effects are discussed.

Discrete vapour cavity model with improved timing of opening and collapse of cavities

NARCIS (Netherlands)

Bergant, A.; Tijsseling, A.S.; Vítkovský, J.P.; Simpson, A.R.; Lambert, M.F.

2007-01-01

Transient vaporous cavitation occurs in hydraulic piping systems when the liquid pressure falls to the vapour pressure. Cavitation may occur as a localized vapour cavity (large void fraction) or as distributed vaporous cavitation (small void fraction). The discrete vapour cavity model (DVCM) with

Studies of HOMs in chains of SRF cavities using state-space concatenation scheme

Energy Technology Data Exchange (ETDEWEB)

Galek, Tomasz; Heller, Johann; Flisgen, Thomas; Brackebusch, Korinna; Rienen, Ursula van [Institut fuer Allgemeine Elektrotechnik, Universitaet Rostock (Germany)

2016-07-01

The design of modern superconducting radio frequency cavities for acceleration of charged particle bunches requires intensive numerical simulations, as they typically arise as modules of several multi-cell cavities. A wide variety of parameters vital to the proper operation of accelerating cavities must be optimized and studied. One of the most important issues concerning the SRF cavities is the influence of the higher order modes on the beam quality, in this contribution. For TESLA-like structures with 1.3 GHz accelerating mode, higher order modes are calculated up to 4 GHz, the external quality factor and the shunt/geometrical impedance spectra are analyzed. To compute properties of complete RF modules the state-space concatenation scheme is used. The aspects of the concatenation scheme and its application to the bERLinPro's chain of cavities is discussed.

Progress in the study and construction of the TESLA test facility injector

Energy Technology Data Exchange (ETDEWEB)

Chehab, R.; Bernard, M.; Bourdon, J.C.; Garvey, T. [Paris-11 Univ., 91 - Orsay (France). Lab. de l`Accelerateur Lineaire; Aune, B.; Desmons, M.; Fusellier, J.; Gougnaud, F. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Buhler, S.; Junquera, T. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire] [and others

1995-12-31

A 500 MeV, 1.3 GHz superconducting linear accelerator is being studied and built to serve as a test facility for the TESLA linear collider project. The phase 1 injector consists of a 250 keV electron gun, buncher and a superconducting capture cavity at the main linac frequency. The main characteristics (intensity, position, emittance, bunch length, energy spread) are to be measured using different techniques. A particular effort will be made on the use of optical transition radiation (OTR) for the determination of the transverse beam emittance as well as the bunch length. (K.A.). 7 refs.

Progress in the study and construction of the TESLA test facility injector

International Nuclear Information System (INIS)

Chehab, R.; Bernard, M.; Bourdon, J.C.; Garvey, T.; Aune, B.; Desmons, M.; Fusellier, J.; Gougnaud, F.; Buhler, S.; Junquera, T.

1995-01-01

A 500 MeV, 1.3 GHz superconducting linear accelerator is being studied and built to serve as a test facility for the TESLA linear collider project. The phase 1 injector consists of a 250 keV electron gun, buncher and a superconducting capture cavity at the main linac frequency. The main characteristics (intensity, position, emittance, bunch length, energy spread) are to be measured using different techniques. A particular effort will be made on the use of optical transition radiation (OTR) for the determination of the transverse beam emittance as well as the bunch length. (K.A.)

COMPARISON OF RF CAVITY TRANSPORT MODELS FOR BBU SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Ilkyoung Shin,Byung Yunn,Todd Satogata,Shahid Ahmed

2011-03-01

The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.

Comparison Of RF Cavity Transport Models For BBU Simulations

International Nuclear Information System (INIS)

Shin, Ilkyoung; Yunn, Byung; Satogata, Todd; Ahmed, Shahid

2011-01-01

The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.

Superconducting radio frequency cavities: design, development and results

International Nuclear Information System (INIS)

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

2013-01-01

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

Two-channel interaction models in cavity QED

International Nuclear Information System (INIS)

Wang, L.

1993-01-01

The authors introduce four fully quantized models of light-matter interactions in optical or microwave cavities. These are the first exactly soluble models in cavity quantum electrodynamics (cavity QED) that provide two transition channels for the flipping of atomic states. In these models a loss-free cavity is assumed to support three or four quantized field modes, which are coupled to a single atom. The atom exchanges photons with the cavity, in either the Raman configuration including both Stokes and anti-Stokes modes, or through two-photon cascade processes. The authors obtain the effective Hamiltonians for these models by adiabatically eliminating an off-resonant intermediate atomic level, and discuss their novel properties in comparison to the existing one-channel Jaynes-Cummings models. They give a detailed description of a method to find exact analytic solutions for the eigenfunctions and eigenvalues for the Hamiltonians of four models. These are also valid when the AC Stark shifts are included. It is shown that the eigenvalues can be expressed in very simple terms, and formulas for normalized eigenvectors are also given, as well as discussions of some of their simple properties. Heisenberg picture equations of motions are derived for several operators with solutions provided in a couple of cases. The dynamics of the systems with both Fock state and coherent state fields are demonstrated and discussed using the model's two key variables, the atomic inversion and the expectation value of photon number. Clear evidences of high efficiency mode-mixing are seen in both the Raman and cascade configurations, and different kinds of collapses and revivals are encountered in the atomic inversions. Effects of several factors like the AC Stark shift and variations in the complex coupling constants are also illustrated

Optimizing Centrifugal Barrel Polishing For Mirror Finish SRF Cavity And RF Tests At Jefferson Lab

International Nuclear Information System (INIS)

Palczewski, Ari; Geng, Rongli; Tian, Hui

2012-01-01

We performed Centrifugal Barrel Polishing (CBP) on a 1.3 GHz fine grain TESLA single cell cavity and 1.5 GHz fine grain CEBAF high gradient superconducting radio frequency (SRF) single cell cavity following a modified recipe originally developed at Fermi National Accelerator Lab (FNAL). We were able to obtain a mirror like surface similar to that obtained at FNAL, while reducing the number of CBP steps and total processing time. This paper will discuss the change in surface and subsequent cavity performance post CBP, after a 800 C bake (no pre-bake chemistry) and minimal controlled electro-polishing (10 micron). In addition to Q vs. E ACC thermometry mapping with preheating characteristics and optical inspection of the cavity after CBP will also be shown.

The success of the 11-Tesla project and its potential beyond particle physics

CERN Multimedia

CERN Bulletin

2013-01-01

On 7 March, the 1-metre-long single-aperture dipole model magnet under testing at Fermilab reached a current of 12.54 kA corresponding to a bore field of 11.5 Tesla, thus surpassing the goal set for the 11 T dipole project.   Computer generated model of the FNAL 1 metre 11 T dipole model magnet and a pair of CERN coils. Image: courtesy of Don Mitchell, FNAL. The 11-Tesla dipole project originated from a proposal made by High Luminosity LHC project coordinator, Lucio Rossi, in September 2010. To cope with the increasing amount of debris hitting the magnets when increasing the number of collisions produced by the LHC, he suggested replacing a few 8-Tesla dipole magnets in the LHC tunnel with shorter, stronger 11-Tesla magnets in order to create enough space to install additional collimators. The only way to achieve this goal is to use advanced niobium-tin technology. Rossi’s proposal aligned well with the goals of Fermilab’s High-Field Magnet R&D programme, which aims t...

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

Calculation of secondary capacitance of compact Tesla pulse transformer

International Nuclear Information System (INIS)

Yu Binxiong; Liu Jinliang

2013-01-01

An analytic expression of the secondary capacitance of a compact Tesla pulse transformer is derived. Calculated result by the expression shows that two parts contribute to the secondary capacitance, namely the capacitance between inner and outer magnetic cores and the attached capacitance caused by the secondary winding. The attached capacitance equals to the capacitance of a coaxial line which is as long as the secondary coil, and whose outer and inner diameters are as large as the inner diameter of the outer magnetic and the outer diameter of the inner magnetic core respectively. A circuital model for analyzing compact Tesla transformer is built, and numeric calculation shows that the expression of the secondary capacitance is correct. Besides, a small compact Tesla transformer is developed, and related test is carried out. Test result confirms the calculated results by the expression derived. (authors)

Small horizontal emittance in the TESLA damping ring

International Nuclear Information System (INIS)

Decking, W.

2001-01-01

The present TESLA damping ring is designed for a normalized horizontal emittance of 8x10 -6 m. γ-γ collisions at the TESLA linear collider will benefit from a further decrease of the horizontal emittance. This paper reviews the processes which limit the horizontal emittance in the damping ring. Preliminary estimates on the smallest horizontal emittance for the present TESLA damping ring design as well as an ultimate limit of the emittance reachable with the TESLA damping ring concept will be given

In vivo high-resolution 7 Tesla MRI shows early and diffuse cortical alterations in CADASIL.

Science.gov (United States)

De Guio, François; Reyes, Sonia; Vignaud, Alexandre; Duering, Marco; Ropele, Stefan; Duchesnay, Edouard; Chabriat, Hugues; Jouvent, Eric

2014-01-01

Recent data suggest that early symptoms may be related to cortex alterations in CADASIL (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), a monogenic model of cerebral small vessel disease (SVD). The aim of this study was to investigate cortical alterations using both high-resolution T2* acquisitions obtained with 7 Tesla MRI and structural T1 images with 3 Tesla MRI in CADASIL patients with no or only mild symptomatology (modified Rankin's scale ≤1 and Mini Mental State Examination (MMSE) ≥24). Complete reconstructions of the cortex using 7 Tesla T2* acquisitions with 0.7 mm isotropic resolution were obtained in 11 patients (52.1±13.2 years, 36% male) and 24 controls (54.8±11.0 years, 42% male). Seven Tesla T2* within the cortex and cortical thickness and morphology obtained from 3 Tesla images were compared between CADASIL and control subjects using general linear models. MMSE, brain volume, cortical thickness and global sulcal morphology did not differ between groups. By contrast, T2* measured by 7 Tesla MRI was significantly increased in frontal, parietal, occipital and cingulate cortices in patients after correction for multiple testing. These changes were not related to white matter lesions, lacunes or microhemorrhages in patients having no brain atrophy compared to controls. Seven Tesla MRI, by contrast to state of the art post-processing of 3 Tesla acquisitions, shows diffuse T2* alterations within the cortical mantle in CADASIL whose origin remains to be determined.

In vivo high-resolution 7 Tesla MRI shows early and diffuse cortical alterations in CADASIL.

Directory of Open Access Journals (Sweden)

François De Guio

Full Text Available Recent data suggest that early symptoms may be related to cortex alterations in CADASIL (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy, a monogenic model of cerebral small vessel disease (SVD. The aim of this study was to investigate cortical alterations using both high-resolution T2* acquisitions obtained with 7 Tesla MRI and structural T1 images with 3 Tesla MRI in CADASIL patients with no or only mild symptomatology (modified Rankin's scale ≤1 and Mini Mental State Examination (MMSE ≥24.Complete reconstructions of the cortex using 7 Tesla T2* acquisitions with 0.7 mm isotropic resolution were obtained in 11 patients (52.1±13.2 years, 36% male and 24 controls (54.8±11.0 years, 42% male. Seven Tesla T2* within the cortex and cortical thickness and morphology obtained from 3 Tesla images were compared between CADASIL and control subjects using general linear models.MMSE, brain volume, cortical thickness and global sulcal morphology did not differ between groups. By contrast, T2* measured by 7 Tesla MRI was significantly increased in frontal, parietal, occipital and cingulate cortices in patients after correction for multiple testing. These changes were not related to white matter lesions, lacunes or microhemorrhages in patients having no brain atrophy compared to controls.Seven Tesla MRI, by contrast to state of the art post-processing of 3 Tesla acquisitions, shows diffuse T2* alterations within the cortical mantle in CADASIL whose origin remains to be determined.

NIKOLA TESLA AND THE X-RAY

OpenAIRE

Rade R. Babic

2005-01-01

After professor Wilhelm Konrad Röntgen published his study of an x-ray discovery (Academy Bulletin, Berlin, 08. 11. 1895.), Nikola Tesla published his first study of an x-ray on the 11th of March in 1896. (X-ray, Electrical Review). Until the 11th of August in 1897 he had published ten studies on this subject. All Tesla,s x-ray studies were experimental, which is specific to his work. Studying the nature of the x-ray, he established a new medical branch-radiology. He wrote:” There’s no doubt...

Tesla Roadsterin vauriokorjaus

OpenAIRE

Hiltunen, Santeri

2016-01-01

Insinöörityössä perehdyttiin Tesla-sähköauton rakenteeseen sekä korjaamiseen, sähkötyö-turvallisuuteen sekä sähkötekniikkaan. Työn tavoitteena on selvittää, mitä laki vaatii sähköauton korjaamiseen, ja kuinka saada varaosia ja ohjeita ajoneuvoon, jolla ei ole Suomessa maahantuojaa. Lisäksi tavoitteena oli selvittää, minkälainen auto on kyseessä sekä mitä materiaaleja autoon on käytetty. Työssä korjattiin takaosasta mekaanisilta osiltaan vaurioitunut Tesla Roadster -merkkinen sähköaut...

Influence from cavity decay on geometric quantum computation in the large-detuning cavity QED model

International Nuclear Information System (INIS)

Chen Changyong; Zhang Xiaolong; Deng Zhijiao; Gao Kelin; Feng Mang

2006-01-01

We introduce a general displacement operator to investigate the unconventional geometric quantum computation with dissipation under the model of many identical three-level atoms in a cavity, driven by a classical field. Our concrete calculation is made for the case of two atoms, based on a previous scheme [S.-B. Zheng, Phys. Rev. A 70, 052320 (2004)] for the large-detuning interaction of the atoms with the cavity mode. The analytical results we present will be helpful for experimental realization of geometric quantum computation in real cavities

Modelling of diamond deposition microwave cavity generated plasmas

International Nuclear Information System (INIS)

Hassouni, K; Silva, F; Gicquel, A

2010-01-01

Some aspects of the numerical modelling of diamond deposition plasmas generated using microwave cavity systems are discussed. The paper mainly focuses on those models that allow (i) designing microwave cavities in order to optimize the power deposition in the discharge and (ii) estimating the detailed plasma composition in the vicinity of the substrate surface. The development of hydrogen plasma models that may be used for the self-consistent simulation of microwave cavity discharge is first discussed. The use of these models for determining the plasma configuration, composition and temperature is illustrated. Examples showing how to use these models in order to optimize the cavity structure and to obtain stable process operations are also given. A transport model for the highly reactive H 2 /CH 4 moderate pressure discharges is then presented. This model makes possible the determination of the time variation of plasma composition and temperature on a one-dimensional domain located on the plasma axis. The use of this model to analyse the transport phenomena and the chemical process in diamond deposition plasmas is illustrated. The model is also utilized to analyse pulsed mode discharges and the benefit they can bring as far as diamond growth rate and quality enhancement are concerned. We, in particular, show how the model can be employed to optimize the pulse waveform in order to improve the deposition process. Illustrations on how the model can give estimates of the species density at the growing substrate surface over a wide domain of deposition conditions are also given. This brings us to discuss the implication of the model prediction in terms of diamond growth rate and quality. (topical review)

TeSLA e-assessment workshop pilot 2

OpenAIRE

Janssen, José

2017-01-01

Presentatie ten behoeve van de e-assessment workshop voor docenten van de Open Universiteit Nederland betrokken in de tweede TeSLA pilot. Topics: toetsfraude, toetsdesign, technologie voor authenticatie en verificatie van auteurschap, TeSLA instrument.

Demountable damped cavity for HOM-damping in ILC superconducting accelerating cavities

Energy Technology Data Exchange (ETDEWEB)

Konomi, T., E-mail: konomi@ims.ac.jp [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yasuda, F. [University of Tokyo, Bunkyo-ku, Tokyo 113-8654 (Japan); Furuta, F. [Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, NY 14853 (United States); Saito, K. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2014-01-11

We have designed a new higher-order-mode (HOM) damper called a demountable damped cavity (DDC) as part of the R and D efforts for the superconducting cavity of the International Linear Collider (ILC). The DDC has two design concepts. The first is an axially symmetrical layout to obtain high damping efficiency. The DDC has a coaxial structure along the beam axis to realize strong coupling with HOMs. HOMs are damped by an RF absorber at the end of the coaxial waveguide and the accelerating mode is reflected by a choke filter mounted at the entrance of the coaxial waveguide. The second design concept is a demountable structure to facilitate cleaning, in order to suppress the Q-slope problem in a high field. A single-cell cavity with the DDC was fabricated to test four performance parameters. The first was frequency matching between the accelerating cavity and the choke filter. Since the bandwidth of the resonance frequency in a superconducting cavity is very narrow, there is a possibility that the accelerating field will leak to the RF absorber because of thermal shrinkage. The design bandwidth of the choke filter is 25 kHz. It was demonstrated that frequency matching adjusted at room temperature could be successfully maintained at 2 K. The second parameter was the performance of the demountable structure. At the joint, the magnetic field is 1/6 of the maximum field in the accelerating cavity. Ultimately, the accelerating field reached 19 MV/m and Q{sub 0} was 1.5×10{sup 10} with a knife-edge shape. The third parameter was field emission and multipacting. Although the choke structure has numerous parallel surfaces that are susceptible to the multipacting problem, it was found that neither field emission nor multipacting presented problems in both an experiment and simulation. The final parameter was the Q values of the HOM. The RF absorber adopted in the system is a Ni–Zn ferrite type. The RF absorber shape was designed based on the measurement data of permittivity

Demountable damped cavity for HOM-damping in ILC superconducting accelerating cavities

International Nuclear Information System (INIS)

Konomi, T.; Yasuda, F.; Furuta, F.; Saito, K.

2014-01-01

We have designed a new higher-order-mode (HOM) damper called a demountable damped cavity (DDC) as part of the R and D efforts for the superconducting cavity of the International Linear Collider (ILC). The DDC has two design concepts. The first is an axially symmetrical layout to obtain high damping efficiency. The DDC has a coaxial structure along the beam axis to realize strong coupling with HOMs. HOMs are damped by an RF absorber at the end of the coaxial waveguide and the accelerating mode is reflected by a choke filter mounted at the entrance of the coaxial waveguide. The second design concept is a demountable structure to facilitate cleaning, in order to suppress the Q-slope problem in a high field. A single-cell cavity with the DDC was fabricated to test four performance parameters. The first was frequency matching between the accelerating cavity and the choke filter. Since the bandwidth of the resonance frequency in a superconducting cavity is very narrow, there is a possibility that the accelerating field will leak to the RF absorber because of thermal shrinkage. The design bandwidth of the choke filter is 25 kHz. It was demonstrated that frequency matching adjusted at room temperature could be successfully maintained at 2 K. The second parameter was the performance of the demountable structure. At the joint, the magnetic field is 1/6 of the maximum field in the accelerating cavity. Ultimately, the accelerating field reached 19 MV/m and Q 0 was 1.5×10 10 with a knife-edge shape. The third parameter was field emission and multipacting. Although the choke structure has numerous parallel surfaces that are susceptible to the multipacting problem, it was found that neither field emission nor multipacting presented problems in both an experiment and simulation. The final parameter was the Q values of the HOM. The RF absorber adopted in the system is a Ni–Zn ferrite type. The RF absorber shape was designed based on the measurement data of permittivity and

T2 relaxation time in patellar cartilage - global and regional reproducibility at 1.5 Tesla and 3 Tesla

International Nuclear Information System (INIS)

Glaser, C.; Horng, A.; Mendlik, T.; Weckbach, S.; Hoffmann, R.T.; Wagner, S.; Raya, J.G.; Reiser, M.; Horger, W.

2007-01-01

Purpose: Evaluation of the global and regional reproducibility of T2 relaxation time in patellar cartilage at 1.5 T and 3 T. Materials and Methods: 6 left patellae of 6 healthy volunteers (aged 25-30, 3 female, 3 male) were examined using a fat-saturated multiecho sequence and a T1-w 3D-FLASH sequence with water excitation at 1.5 Tesla and 3 Tesla. Three consecutive data sets were acquired within one MRI session with the examined knee being repositioned in the coil and scanner between each data set. The segmented cartilage (FLASH sequence) was overlaid on the multiecho data and T2 values were calculated for the total cartilage, 3 horizontal layers consisting of a superficial, intermedial and deep layer, 3 facets consisting of a medial, median (ridge) and lateral facet (global T2 values) and 27 ROIs/MRI slices (regional T2 value). The reproducibility (precision error) was calculated as the root mean square average of the individual standard deviations [ms] and coefficients of variation (COV) [%]. Results: The mean global reproducibility error for T2 was 3.53% (±0.38%) at 1.5 Tesla and 3.25% (±0.61%) at 3 Tesla. The mean regional reproducibility error for T2 was 8.62% (±2.61%) at 1.5 Tesla and 9.66% (±3.37%) at 3 Tesla. There was no significant difference with respect to absolute reproducibility errors between 1.5 Tesla and 3 Tesla at a constant spatial resolution. However, different reproducibility errors were found between the cartilage layers. One third of the data variability could be attributed to the influence of the different cartilage layers, and another 10% to the influence of the separate MRI slices. Conclusion: Our data provides an estimation of the global and regional reproducibility errors of T2 in healthy cartilage. In the analysis of small subregions, an increase in the regional reproducibility error must be accepted. The data may serve as a basis for sample size calculations of study populations and may contribute to the decision regarding the

TeSLA workshop betrouwbaar toetsen op afstand

NARCIS (Netherlands)

Brouns, Francis; Janssen, José

2017-01-01

Presentatie ten behoeve van workshop betrouwbaar toetsen op afstand voor docenten van de Open Universiteit Nederland betrokken in de derde TeSLA pilot. Topics: toetsfraude, toetsdesign, technologie voor authenticatie en verificatie van auteurschap, TeSLA instrumenten.

A technique for monitoring fast tuner piezoactuator preload forces for superconducting rf cavities

International Nuclear Information System (INIS)

Pischalnikov, Y.; Branlard, J.; Carcagno, R.; Chase, B.; Edwards, H.; Orris, D.; Makulski, A.; McGee, M.; Nehring, R.; Poloubotko, V.; Sylvester, C.; Fermilab

2007-01-01

The technology for mechanically compensating Lorentz Force detuning in superconducting RF cavities has already been developed at DESY. One technique is based on commercial piezoelectric actuators and was successfully demonstrated on TESLA cavities [1]. Piezo actuators for fast tuners can operate in a frequency range up to several kHz; however, it is very important to maintain a constant static force (preload) on the piezo actuator in the range of 10 to 50% of its specified blocking force. Determining the preload force during cool-down, warm-up, or re-tuning of the cavity is difficult without instrumentation, and exceeding the specified range can permanently damage the piezo stack. A technique based on strain gauge technology for superconducting magnets has been applied to fast tuners for monitoring the preload on the piezoelectric assembly. The design and testing of piezo actuator preload sensor technology is discussed. Results from measurements of preload sensors installed on the tuner of the Capture Cavity II (CCII)[2] tested at FNAL are presented. These results include measurements during cool-down, warmup, and cavity tuning along with dynamic Lorentz force compensation

A technique for monitoring fast tuner piezoactuator preload forces for superconducting rf cavities

Energy Technology Data Exchange (ETDEWEB)

Pischalnikov, Y.; Branlard, J.; Carcagno, R.; Chase, B.; Edwards, H.; Orris, D.; Makulski, A.; McGee, M.; Nehring, R.; Poloubotko, V.; Sylvester, C.; /Fermilab

2007-06-01

The technology for mechanically compensating Lorentz Force detuning in superconducting RF cavities has already been developed at DESY. One technique is based on commercial piezoelectric actuators and was successfully demonstrated on TESLA cavities [1]. Piezo actuators for fast tuners can operate in a frequency range up to several kHz; however, it is very important to maintain a constant static force (preload) on the piezo actuator in the range of 10 to 50% of its specified blocking force. Determining the preload force during cool-down, warm-up, or re-tuning of the cavity is difficult without instrumentation, and exceeding the specified range can permanently damage the piezo stack. A technique based on strain gauge technology for superconducting magnets has been applied to fast tuners for monitoring the preload on the piezoelectric assembly. The design and testing of piezo actuator preload sensor technology is discussed. Results from measurements of preload sensors installed on the tuner of the Capture Cavity II (CCII)[2] tested at FNAL are presented. These results include measurements during cool-down, warmup, and cavity tuning along with dynamic Lorentz force compensation.

JACoW N-doped niobium accelerating cavities: Analyzing model applicability

CERN Document Server

Eichhorn, Ralf; Weingarten, Wolfgang

2017-01-01

The goal of this research was to analyse data from multiple cavities in order to test the viability of a model for surface resistance proposed previously. The model intends to describe the behaviour of the quality factor with respect to the RF field strength, while exploring the physical cause of this phenomenon; the model is pretty general, but will be checked here specifically for N-doped niobium cavities. The data were obtained from two single-cell 1.3 GHz cavities manufactured and tested at Jefferson Lab in Newport News, VA, USA.

[Nikola Tesla in medicine, too].

Science.gov (United States)

Hanzek, Branko; Jakobović, Zvonimir

2007-12-01

Using primary and secondary sources we have shown in this paper the influence of Nikola Tesla's work on the field of medicine. The description of his experiments conduced within secondary-school education programs aimed to present the popularization of his work in Croatia. Although Tesla was dedicated primarily to physics and was not directly involved in biomedical research, his work significantly contributed to paving the way of medical physics particularly radiology and high-frequency electrotherapy.

Quantitative techniques for musculoskeletal MRI at 7 Tesla.

Science.gov (United States)

Bangerter, Neal K; Taylor, Meredith D; Tarbox, Grayson J; Palmer, Antony J; Park, Daniel J

2016-12-01

Whole-body 7 Tesla MRI scanners have been approved solely for research since they appeared on the market over 10 years ago, but may soon be approved for selected clinical neurological and musculoskeletal applications in both the EU and the United States. There has been considerable research work on musculoskeletal applications at 7 Tesla over the past decade, including techniques for ultra-high resolution morphological imaging, 3D T2 and T2* mapping, ultra-short TE applications, diffusion tensor imaging of cartilage, and several techniques for assessing proteoglycan content in cartilage. Most of this work has been done in the knee or other extremities, due to technical difficulties associated with scanning areas such as the hip and torso at 7 Tesla. In this manuscript, we first provide some technical context for 7 Tesla imaging, including challenges and potential advantages. We then review the major quantitative MRI techniques being applied to musculoskeletal applications on 7 Tesla whole-body systems.

A statistical model for field emission in superconducting cavities

International Nuclear Information System (INIS)

Padamsee, H.; Green, K.; Jost, W.; Wright, B.

1993-01-01

A statistical model is used to account for several features of performance of an ensemble of superconducting cavities. The input parameters are: the number of emitters/area, a distribution function for emitter β values, a distribution function for emissive areas, and a processing threshold. The power deposited by emitters is calculated from the field emission current and electron impact energy. The model can successfully account for the fraction of tests that reach the maximum field Epk in an ensemble of cavities, for eg, 1-cells at sign 3 GHz or 5-cells at sign 1.5 GHz. The model is used to predict the level of power needed to successfully process cavities of various surface areas with high pulsed power processing (HPP)

New Tesla-Experiment; Neue Tesla-Experimente

Energy Technology Data Exchange (ETDEWEB)

Wahl, Guenter; Harthun, Norbert

2010-07-01

Mysterious Teslar wave, microwave and scalar wave generators are presented, as well as exotic Star Wars experiments like mass accelerators and plasma guns. The third section describes, among others, a tube-driven Tesla generator with 50 cm streamers. The reader will also find a catalogue of Messrs. Information Unlimited, USA, who are providers of many of the kits, circuiting diagrams and apparatuses presented here. Main topic in this issue is wireless energy transfer and telecommunication engineering.(orig./GL)

Modified 3½-Cell SC Cavity Made of Large Grain Niobium for the FZD SRF Photoinjector

CERN Document Server

Murcek, P; Michel, P; Moeller, K; Arnold, A; Teichert, J; Xiang, R; Freitag, M; Kneisel, P

2010-01-01

An SRF photoinjector has been successfully tested in FZD under the collaboration of BESSY, DESY, FZD, and MBI. In order to improve the gun cavity quality and thus reach a higher gradient, a new 3+1/2 superconducting cavity is being fabricated in cooperation with JLab. The modified cavity is made of large grain niobium, composed of one filter choke, one special designed half-cell (gun-cell) and three TESLA cavities. In this paper, the main updates of the new cavity design will be explained in detail. The deformation of the filter choke and the gun-cell, which is caused by pressure fluctuation in the He-line and also by the effect of the Lorentz force, will be minimized by stiffening between the filter choke and the gun-cell. Meanwhile, the cathode hole in the choke and gun-cell is enlarged for better rinsing. To simplify assembly, the NbTi pick-up will be welded directly on the wall of filter choke.

Tesla the life and times of an electric messiah

CERN Document Server

Cawthorne, Nigel

2014-01-01

Despite being incredibly popular during his time, Nikola Tesla today remains largely overlooked among lists of the greatest inventors and scientists of the modern era.  Thomas Edison gets all the glory for discovering the light bulb, but it was his one time assistant and life long arch nemesis, Tesla, who made the breakthrough in alternating current technology.  Edison and Tesla carried on a bitter feud for years, but it was Tesla's AC generators that illuminated the 1893 World's Fair in Chicago; the first time that an event of such magnitude had ever taken place under artificial light.  Today, all homes and electrical appliances run on Tesla's AC current.Born in Croatia in 1856, Tesla spoke eight languages and as well as almost single handedly developing household electricity.  During his life, he patented more than 700 inventions.  He invented electrical generators, FM radio, remote control robots, spark plugs and fluorescent lights.  He had a photographic memory and did advanced calculus and physic...

TeSLA pilot 2 pedagogical & quality aspects

OpenAIRE

Janssen, José

2018-01-01

Presentation given at the TeSLA project meeting at the Open University of the Netherlands, addressing pedagogical aspects of pilot 2 and clarification of the scope and limitations of the TeSLA instruments with respect to pedagogy, assessment activity and type of academic dishonesty.

Non-Enhanced MR Imaging of Cerebral Arteriovenous Malformations at 7 Tesla.

Science.gov (United States)

Wrede, Karsten H; Dammann, Philipp; Johst, Sören; Mönninghoff, Christoph; Schlamann, Marc; Maderwald, Stefan; Sandalcioglu, I Erol; Ladd, Mark E; Forsting, Michael; Sure, Ulrich; Umutlu, Lale

2016-03-01

To evaluate prospectively 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) and 7 Tesla non-contrast-enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of intracerebral arteriovenous malformations (AVMs) in comparison to 1.5 Tesla TOF MRA and digital subtraction angiography (DSA). Twenty patients with single or multifocal AVMs were enrolled in this trial. The study protocol comprised 1.5 and 7 Tesla TOF MRA and 7 Tesla non-contrast-enhanced MPRAGE sequences. All patients underwent an additional four-vessel 3D DSA. Image analysis of the following five AVM features was performed individually by two radiologists on a five-point scale: nidus, feeder(s), draining vein(s), relationship to adjacent vessels, and overall image quality and presence of artefacts. A total of 21 intracerebral AVMs were detected. Both sequences at 7 Tesla were rated superior over 1.5 Tesla TOF MRA in the assessment of all considered AVM features. Image quality at 7 Tesla was comparable with DSA considering both sequences. Inter-observer accordance was good to excellent for the majority of ratings. This study demonstrates excellent image quality for depiction of intracerebral AVMs using non-contrast-enhanced 7 Tesla MRA, comparable with DSA. Assessment of untreated AVMs is a promising clinical application of ultra-high-field MRA. • Non-contrast-enhanced 7 Tesla MRA demonstrates excellent image quality for intracerebral AVM depiction. • Image quality at 7 Tesla was comparable with DSA considering both sequences. • Assessment of intracerebral AVMs is a promising clinical application of ultra-high-field MRA.

Tesla man out of time

CERN Document Server

Cheney, Margaret

1981-01-01

Called a madman by some, a genius by others, and an enigma by nearly everyone, Nikola Tesla created astonishing, world-transforming devises that were virtually without theoretical precedent. Tesla not only discovered the rotating magnetic field, the basis of most alternating current machinery, but also introduced the fundamentals of robotry, computers, and missile science and helped pave the way for such technologies as satellites, microwaves, beam weapons, and nuclear fusion. Almost supernaturally gifted, Tesla was also unusually erratic, flamboyant, and neurotic. He was J. P. Morgan's client, counted Mark Twain as a friend, and considered Thomas Edison an enemy. But above all, he was the hero and mentor to many of the last century's most famous scientists. In a meticulously researched, engagingly written biography, Margaret Cheney presents the many different dimensions of this extraordinary man, capturing his human qualities and quirks as she chronicles a lifetime of discoveries that continue to alter our ...

Emittance damping considerations for TESLA

International Nuclear Information System (INIS)

Floettmann, K.; Rossbach, J.

1993-03-01

Two schemes are considered to avoid very large damping rings for TESLA. The first (by K.F.) makes use of the linac tunnel to accomodate most of the damping 'ring' structure, which is, in fact, not a ring any more but a long linear structure with two small bends at each of its ends ('dog-bone'). The other scheme (by J.R.) is based on a positron (or electron, respectively) recycling scheme. It makes use of the specific TESLA property, that the full bunch train is much longer (240 km) than the linac length. The spent beams are recycled seven times after interaction, thus reducing the number of bunches to be stored in the damping ring by a factor of eight. Ultimately, this scheme can be used to operate TESLA in a storage ring mode ('storage linac'), with no damping ring at all. Finally, a combination of both schemes is considered. (orig.)

Nikola Tesla: the man behind the magnetic field unit.

Science.gov (United States)

Roguin, Ariel

2004-03-01

The magnetic field strength of both the magnet and gradient coils used in MR imaging equipment is measured in Tesla units, which are named for Nikola Tesla. This article presents the life and achievements of this Serbian-American inventor and researcher who discovered the rotating magnetic field, the basis of most alternating-current machinery. Nikola Tesla had 700 patents in the United States and Europe that covered every aspect of science and technology. Tesla's discoveries include the Tesla coil, AC electrical conduction, improved lighting, newer forms of turbine engines, robotics, fluorescent light, wireless transmission of electrical energy, radio, remote control, discovery of cosmic radio waves, and the use of the ionosphere for scientific purposes. He was a genius whose discoveries had a pivotal role in advancing us into the modern era. Copyright 2004 Wiley-Liss, Inc.

Non-enhanced MR imaging of cerebral arteriovenous malformations at 7 Tesla

International Nuclear Information System (INIS)

Wrede, Karsten H.; Dammann, Philipp; Johst, Soeren; Maderwald, Stefan; Moenninghoff, Christoph; Forsting, Michael; Schlamann, Marc; Sandalcioglu, I.E.; Ladd, Mark E.; Sure, Ulrich; Umutlu, Lale

2016-01-01

To evaluate prospectively 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) and 7 Tesla non-contrast-enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of intracerebral arteriovenous malformations (AVMs) in comparison to 1.5 Tesla TOF MRA and digital subtraction angiography (DSA). Twenty patients with single or multifocal AVMs were enrolled in this trial. The study protocol comprised 1.5 and 7 Tesla TOF MRA and 7 Tesla non-contrast-enhanced MPRAGE sequences. All patients underwent an additional four-vessel 3D DSA. Image analysis of the following five AVM features was performed individually by two radiologists on a five-point scale: nidus, feeder(s), draining vein(s), relationship to adjacent vessels, and overall image quality and presence of artefacts. A total of 21 intracerebral AVMs were detected. Both sequences at 7 Tesla were rated superior over 1.5 Tesla TOF MRA in the assessment of all considered AVM features. Image quality at 7 Tesla was comparable with DSA considering both sequences. Inter-observer accordance was good to excellent for the majority of ratings. This study demonstrates excellent image quality for depiction of intracerebral AVMs using non-contrast-enhanced 7 Tesla MRA, comparable with DSA. Assessment of untreated AVMs is a promising clinical application of ultra-high-field MRA. (orig.)

Non-enhanced MR imaging of cerebral arteriovenous malformations at 7 Tesla

Energy Technology Data Exchange (ETDEWEB)

Wrede, Karsten H.; Dammann, Philipp [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, Department of Neurosurgery, Essen (Germany); Johst, Soeren; Maderwald, Stefan [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); Moenninghoff, Christoph; Forsting, Michael [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); Schlamann, Marc [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); University Hospital Giessen, Department of Neuroradiology, Giessen (Germany); Sandalcioglu, I.E. [University Hospital Essen, Department of Neurosurgery, Essen (Germany); Nordstadtkrankenhaus Hannover, Department of Neurosurgery, Hannover (Germany); Ladd, Mark E. [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany); German Cancer Research Center (DKFZ), Division of Medical Physics in Radiology (E020), Heidelberg (Germany); Sure, Ulrich [University Hospital Essen, Department of Neurosurgery, Essen (Germany); Umutlu, Lale [University Duisburg-Essen, Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen (Germany); University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany)

2016-03-15

To evaluate prospectively 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) and 7 Tesla non-contrast-enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of intracerebral arteriovenous malformations (AVMs) in comparison to 1.5 Tesla TOF MRA and digital subtraction angiography (DSA). Twenty patients with single or multifocal AVMs were enrolled in this trial. The study protocol comprised 1.5 and 7 Tesla TOF MRA and 7 Tesla non-contrast-enhanced MPRAGE sequences. All patients underwent an additional four-vessel 3D DSA. Image analysis of the following five AVM features was performed individually by two radiologists on a five-point scale: nidus, feeder(s), draining vein(s), relationship to adjacent vessels, and overall image quality and presence of artefacts. A total of 21 intracerebral AVMs were detected. Both sequences at 7 Tesla were rated superior over 1.5 Tesla TOF MRA in the assessment of all considered AVM features. Image quality at 7 Tesla was comparable with DSA considering both sequences. Inter-observer accordance was good to excellent for the majority of ratings. This study demonstrates excellent image quality for depiction of intracerebral AVMs using non-contrast-enhanced 7 Tesla MRA, comparable with DSA. Assessment of untreated AVMs is a promising clinical application of ultra-high-field MRA. (orig.)

Thermal modeling of a pressurized air cavity receiver for solar dish Stirling system

Science.gov (United States)

Zou, Chongzhe; Zhang, Yanping; Falcoz, Quentin; Neveu, Pierre; Li, Jianlan; Zhang, Cheng

2017-06-01

A solar cavity receiver model for the dish collector system is designed in response to growing demand of renewable energy. In the present research field, no investigations into the geometric parameters of a cavity receiver have been performed. The cylindrical receiver in this study is composed of an enclosed bottom at the back, an aperture at the front, a helical pipe inside the cavity and an insulation layer on the external surface of the cavity. The influence of several critical receiver parameters on the thermal efficiency is analyzed in this paper: cavity inner diameter and cavity length. The thermal model in this paper is solved considering the cavity dimensions as variables. Implementing the model into EES, each parameter influence is separately investigated, and a preliminary optimization method is proposed.

Large-Signal Code TESLA: Current Status and Recent Development

National Research Council Canada - National Science Library

Chernyavskiy, Igor A; Vlasov, Alexander N; Cooke, Simon J; Abe, David K; Levush, Baruch; Antonsen, Jr., Thomas M; Nguyen, Khanh T

2008-01-01

.... One such tool is the large-signal code TESLA, which was successfully applied for the modeling of single-beam and multiple-beam klystron devices at the Naval Research Laboratory and which is now used by number of U.S. companies...

1.5 versus 3 versus 7 Tesla in abdominal MRI: A comparative study.

Science.gov (United States)

Laader, Anja; Beiderwellen, Karsten; Kraff, Oliver; Maderwald, Stefan; Wrede, Karsten; Ladd, Mark E; Lauenstein, Thomas C; Forsting, Michael; Quick, Harald H; Nassenstein, Kai; Umutlu, Lale

2017-01-01

The aim of this study was to investigate and compare the feasibility as well as potential impact of altered magnetic field properties on image quality and potential artifacts of 1.5 Tesla, 3 Tesla and 7 Tesla non-enhanced abdominal MRI. Magnetic Resonance (MR) imaging of the upper abdomen was performed in 10 healthy volunteers on a 1.5 Tesla, a 3 Tesla and a 7 Tesla MR system. The study protocol comprised a (1) T1-weighted fat-saturated spoiled gradient-echo sequence (2D FLASH), (2) T1-weighted fat-saturated volumetric interpolated breath hold examination sequence (3D VIBE), (3) T1-weighted 2D in and opposed phase sequence, (4) True fast imaging with steady-state precession sequence (TrueFISP) and (5) T2-weighted turbo spin-echo (TSE) sequence. For comparison reasons field of view and acquisition times were kept comparable for each correlating sequence at all three field strengths, while trying to achieve the highest possible spatial resolution. Qualitative and quantitative analyses were tested for significant differences. While 1.5 and 3 Tesla MRI revealed comparable results in all assessed features and sequences, 7 Tesla MRI yielded considerable differences in T1 and T2 weighted imaging. Benefits of 7 Tesla MRI encompassed an increased higher spatial resolution and a non-enhanced hyperintense vessel signal at 7 Tesla, potentially offering a more accurate diagnosis of abdominal parenchymatous and vasculature disease. 7 Tesla MRI was also shown to be more impaired by artifacts, including residual B1 inhomogeneities, susceptibility and chemical shift artifacts, resulting in reduced overall image quality and overall image impairment ratings. While 1.5 and 3 Tesla T2w imaging showed equivalently high image quality, 7 Tesla revealed strong impairments in its diagnostic value. Our results demonstrate the feasibility and overall comparable imaging ability of T1-weighted 7 Tesla abdominal MRI towards 3 Tesla and 1.5 Tesla MRI, yielding a promising diagnostic potential for

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)

Paul Drude's prediction of nonreciprocal mutual inductance for Tesla transformers.

Science.gov (United States)

McGuyer, Bart

2014-01-01

Inductors, transmission lines, and Tesla transformers have been modeled with lumped-element equivalent circuits for over a century. In a well-known paper from 1904, Paul Drude predicts that the mutual inductance for an unloaded Tesla transformer should be nonreciprocal. This historical curiosity is mostly forgotten today, perhaps because it appears incorrect. However, Drude's prediction is shown to be correct for the conditions treated, demonstrating the importance of constraints in deriving equivalent circuits for distributed systems. The predicted nonreciprocity is not fundamental, but instead is an artifact of the misrepresentation of energy by an equivalent circuit. The application to modern equivalent circuits is discussed.

[Studies of three-dimensional cardiac late gadolinium enhancement MRI at 3.0 Tesla].

Science.gov (United States)

Ishimoto, Takeshi; Ishihara, Masaru; Ikeda, Takayuki; Kawakami, Momoe

2008-12-20

Cardiac late Gadolinium enhancement MR imaging has been shown to allow assessment of myocardial viability in patients with ischemic heart disease. The current standard approach is a 3D inversion recovery sequence at 1.5 Tesla. The aims of this study were to evaluate the technique feasibility and clinical utility of MR viability imaging at 3.0 Tesla in patients with myocardial infarction and cardiomyopathy. In phantom and volunteer studies, the inversion time required to suppress the signal of interests and tissues was prolonged at 3.0 Tesla. In the clinical study, the average inversion time to suppress the signal of myocardium at 3.0 Tesla with respect to MR viability imaging at 1.5 Tesla was at 15 min after the administration of contrast agent (304.0+/-29.2 at 3.0 Tesla vs. 283.9+/-20.9 at 1.5 Tesla). The contrast between infarction and viable myocardium was equal at both field strengths (4.06+/-1.30 at 3.0 Tesla vs. 4.42+/-1.85 at 1.5 Tesla). Even at this early stage, MR viability imaging at 3.0 Tesla provides high quality images in patients with myocardial infarction. The inversion time is significantly prolonged at 3.0 Tesla. The contrast between infarction and viable myocardium at 3.0 Tesla are equal to 1.5 Tesla. Further investigation is needed for this technical improvement, for clinical evaluation, and for limitations.

Nikola Tesla, the Ether and his Telautomaton

Science.gov (United States)

Milar, Kendall

2014-03-01

In the nineteenth century physicists' understanding of the ether changed dramatically. New developments in thermodynamics, energy physics, and electricity and magnetism dictated new properties of the ether. These have traditionally been examined from the perspective of the scientists re-conceptualizing the ether. However Nikola Tesla, a prolific inventor and writer, presents a different picture of nineteenth century physics. Alongside the displays that showcased his inventions he presented alternative interpretations of physical, physiological and even psychical research. This is particularly evident in his telautomaton, a radio remote controlled boat. This invention and Tesla's descriptions of it showcase some of his novel interpretations of physical theories. He offered a perspective on nineteenth century physics that focused on practical application instead of experiment. Sometimes the understanding of physical theories that Tesla reached was counterproductive to his own inventive work; other times he offered new insights. Tesla's utilitarian interpretation of physical theories suggests a more scientifically curious and invested inventor than previously described and a connection between the scientific and inventive communities.

TESLA-N electron scattering with polarized targets at TESLA

International Nuclear Information System (INIS)

Korotokov, V.

2001-01-01

Measurements of polarized eN scattering can be realized at the TESLA linear collider facility at DESY with luminosities that are about two orders of magnitude higher than those expected for other experiments at comparable energies. A large variety of polarized parton distribution and fragmentation functions can be determined with unprecedented accuracy, many of them for the first time

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

Tesla-transformer-type electron beam accelerator

International Nuclear Information System (INIS)

Liu Jinliang; Zhong Huihuang; Tan Qimei; Li Chuanlu; Zhang Jiande

2002-01-01

An electron-beam Tesla-transformer accelerator is described. It consists of the primary storage energy system. Tesla transformer, oil Blumlein pulse form line, and the vacuum diode. The experiments of initial stage showed that diode voltage rises up to about 500 kV with an input of 20 kV and the maximum electron-beam current is about 9 kA, the pulse width is about 50 ns. This device can operate stably and be set up easily

Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity

Science.gov (United States)

Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia

2016-08-01

The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.

4.5 Tesla magnetic field reduces range of high-energy positrons -- Potential implications for positron emission tomography

International Nuclear Information System (INIS)

Wirrwar, A.; Vosberg, H.; Herzog, H.; Halling, H.; Weber, S.; Mueller-Gaertner, H.W.; Forschungszentrum Juelich GmbH

1997-01-01

The authors have theoretically and experimentally investigated the extent to which homogeneous magnetic fields up to 7 Tesla reduce the spatial distance positrons travel before annihilation (positron range). Computer simulations of a noncoincident detector design using a Monte Carlo algorithm calculated the positron range as a function of positron energy and magnetic field strength. The simulation predicted improvements in resolution, defined as full-width at half-maximum (FWHM) of the line-spread function (LSF) for a magnetic field strength up to 7 Tesla: negligible for F-18, from 3.35 mm to 2.73 mm for Ga-68 and from 3.66 mm to 2.68 mm for Rb-82. Also a substantial noise suppression was observed, described by the full-width at tenth-maximum (FWTM) for higher positron energies. The experimental approach confirmed an improvement in resolution for Ga-68 from 3.54 mm at 0 Tesla to 2.99 mm FWHM at 4.5 Tesla and practically no improvement for F-18 (2.97 mm at 0 Tesla and 2.95 mm at 4.5 Tesla). It is concluded that the simulation model is appropriate and that a homogeneous static magnetic field of 4.5 Tesla reduces the range of high-energy positrons to an extent that may improve spatial resolution in positron emission tomography

Proposed applications with implementation techniques of the upcoming renewable energy resource, The Tesla Turbine

International Nuclear Information System (INIS)

Khan, M Usman Saeed; Maqsood, M Irfan; Ali, Ehsan; Jamal, Shah; Javed, M

2013-01-01

Recent research has shown that tesla turbine can be one of the future efficient sources of renewable energy. Modern techniques used for designing of tesla turbine have given optimum results regarding efficiency and applications. In this paper we have suggested fully coordinated applications of tesla turbine in different fields particularly in power generation at both low level and high level generation. In Energy deficient countries the tesla turbine has wide range of applications and it can play an important role in energy management system. Our proposed applications includes, - the use of tesla turbine as renewable energy resource; - using tesla turbine in distributed generation system; - use of tesla turbine at home for power generation; - use of tesla turbine in irrigation channels; - using tesla turbine in hybrid electric vehicles; All applications are explained with the help of flow charts and block diagrams and their implementation techniques are also explained in details. The results of physical experiments and simulations are also included for some applications.

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.

Model-Based, Closed-Loop Control of PZT Creep for Cavity Ring-Down Spectroscopy.

Science.gov (United States)

McCartt, A D; Ognibene, T J; Bench, G; Turteltaub, K W

2014-09-01

Cavity ring-down spectrometers typically employ a PZT stack to modulate the cavity transmission spectrum. While PZTs ease instrument complexity and aid measurement sensitivity, PZT hysteresis hinders the implementation of cavity-length-stabilized, data-acquisition routines. Once the cavity length is stabilized, the cavity's free spectral range imparts extreme linearity and precision to the measured spectrum's wavelength axis. Methods such as frequency-stabilized cavity ring-down spectroscopy have successfully mitigated PZT hysteresis, but their complexity limits commercial applications. Described herein is a single-laser, model-based, closed-loop method for cavity length control.

A new interlock design for the TESLA RF system

International Nuclear Information System (INIS)

Leich, H.; Kahl, J.; Choroba, S.; Grevsmuehl, T.; Heidbrook, N.

2001-01-01

The RF system for TESLA requires a comprehensive interlock system. Usually interlock systems are organized in a hierarchical way. In order to react to different fault conditions in a fast and flexible manner a nonhierarchical organization seems to be the better solution. At the TESLA Test Facility (TTF) at DESY the authors will install a nonhierarchical interlock system that is based on user designed reprogrammable gate-arrays (FPGA's) which incorporate an embedded microcontroller system. This system could be used later for the TESLA linear collider replacing a strictly hierarchical design

Optimization of materials for the parts that compose a Tesla turbine; Otimizacao de materiais para as partes que compoe uma turbina tipo Tesla

Energy Technology Data Exchange (ETDEWEB)

Rocha, Geovana Vilas Boas da, E-mail: geovana_dmp@yahoo.com.br [Universidade Federal de Sao Paulo (UNIFESP), Sao Jose dos Campos, SP (Brazil); Guimaraes, Lamartine N.F.; Placco, Guilherme M., E-mail: guimarae@ieav.cta.br, E-mail: placco@ieav.cta.br [Instituto de Estudos Avancados (IEAv), Sao Jose dos Campos, SP (Brazil). Divisao de Energia Nuclear

2013-07-01

The TERRA project (Tecnologia de Reatores Rapidos Avancados) of the Aeronautica (Brazil) aims to develop the necessary technologies for the design of nuclear microreactors. These, in turn, aim to address the thermal and electrical needs in space vehicles. One of the activities of this project is to build a closed thermal cycle, the Rankine type in order to test a Tesla turbine type developed by the group. In this thermodynamic cycle the water is transformed into steam, which triggers a turbine which, in turn, provide power to the alternator to be converted into electricity. The work presented a survey of the materials available on the national market for machining a Tesla type turbine. The surveys were made considering the characteristics and operating conditions of a specific thermal cycle, the interest of the group. Results: cost-benefit tables for each party of the turbine, characteristics of each material, the machining process, as well as a comparison between one of 304L stainless steel model turbine with a turbine with the selected materials. The results from this study raised the level of sophistication of the research involved the TERRA project, since the study of ideal materials that make up the parts of a Tesla type turbine in a heat cycle is unprecedented.

Living laboratory for Nikola Tesla. Living laboratories, Tesla, Second Life, sustainable construction technologies and renewable energy sources; Wohnlabor fuer Nikola Tesla. Ueber Wohnlabors, Tesla, Second Life, nachhaltige Bautechnologien und erneuerbare Energie

Energy Technology Data Exchange (ETDEWEB)

Redi, Ivan; Redi, Andrea; Jovanovic, Branimir (and others)

2008-07-01

Adventure is the opposite of conventional teaching. Adventure is the moment when experience alone is not enough. Sometimes, courageous people challenge the nature of things, helping us to get new insights and achieve a new viewpoint. The experience-oriented ''work in progress'' university is an adventure of this kind. The book looks into the Tesla laboratory and the Wardenclyffe Tower, both of which could not be completed for financial reasons, and addresses them from today's state of technology. The conceptional section is based on the ''Tesla doctrine'' which comprises fundamental philosophical statements on civilisatory progress. The book presents the results of the investigation. The 16 architectural projects presented here were developed live on the online platform. Second Life, ORTLOS Sim. (orig.)

Tesla inventor of the electrical age

CERN Document Server

Carlson, W Bernard

2013-01-01

Nikola Tesla was a major contributor to the electrical revolution that transformed daily life at the turn of the twentieth century. His inventions, patents, and theoretical work formed the basis of modern AC electricity, and contributed to the development of radio and television. Like his competitor Thomas Edison, Tesla was one of America's first celebrity scientists, enjoying the company of New York high society and dazzling the likes of Mark Twain with his electrical demonstrations. An astute self-promoter and gifted showman, he cultivated a public image of the eccentric genius. Even at t

CERN: Ten-Tesla twin

International Nuclear Information System (INIS)

Anon.

1991-01-01

An important step in the development of the high field superconducting magnets for CERN's proposed LHC proton collider came on 21 October when a 1 metre-long model of the proposed twin-dipole magnet produced a field of 10 Tesla in its two o beam apertures at the design temperature of 1.8K. The LHC designers have to plan for proton beams approaching 8 TeV to attain the right conditions for the quarks and gluons hidden deep inside protons to produce new physics. To contain these very high energy protons in the tight track of the 27-kilometre LEP tunnel would need the strongest magnetic bending power ever used in a full storage ring

Functionality of veterinary identification microchips following low- (0.5 tesla) and high-field (3 tesla) magnetic resonance imaging.

Science.gov (United States)

Piesnack, Susann; Frame, Mairi E; Oechtering, Gerhard; Ludewig, Eberhard

2013-01-01

The ability to read patient identification microchips relies on the use of radiofrequency pulses. Since radiofrequency pulses also form an integral part of the magnetic resonance imaging (MRI) process, the possibility of loss of microchip function during MRI scanning is of concern. Previous clinical trials have shown microchip function to be unaffected by MR imaging using a field strength of 1 Tesla and 1.5. As veterinary MRI scanners range widely in field strength, this study was devised to determine whether exposure to lower or higher field strengths than 1 Tesla would affect the function of different types of microchip. In a phantom study, a total of 300 International Standards Organisation (ISO)-approved microchips (100 each of three different types: ISO FDX-B 1.4 × 9 mm, ISO FDX-B 2.12 × 12 mm, ISO HDX 3.8 × 23 mm) were tested in a low field (0.5) and a high field scanner (3.0 Tesla). A total of 50 microchips of each type were tested in each scanner. The phantom was composed of a fluid-filled freezer pack onto which a plastic pillow and a cardboard strip with affixed microchips were positioned. Following an MRI scan protocol simulating a head study, all of the microchips were accurately readable. Neither 0.5 nor 3 Tesla imaging affected microchip function in this study. © 2013 Veterinary Radiology & Ultrasound.

Instrumentation of the forward region of the TESLA detector

International Nuclear Information System (INIS)

Buesser, Karsten

2004-01-01

The expected beam-beam interaction at the proposed TESLA electron-positron linear collider has a significant impact on the design of the TESLA detector. Especially the instrumentation of the very forward region down to polar angles below 5 mrad will have to handle an immense background of electrons and positrons adding up to TeVs of energy deposition per bunch crossing. Instrumentation down to small angles is crucial not only for the measurement of the luminosity through Bhabha scattering, but also to maximize the hermeticity of the detector. Additionally these charged particles from beamstrahlung have to be measured as part of the feedback system of the TESLA accelerator and could also be used for beam diagnostics. The present design of the TESLA detector foresees two calorimeters in the forward region whose technologies have to meet the requirements regarding detector resolutions and radiation hardness. (orig.)

Modeling and simulation of a molten salt cavity receiver with Dymola

International Nuclear Information System (INIS)

Zhang, Qiangqiang; Li, Xin; Wang, Zhifeng; Zhang, Jinbai; El-Hefni, Baligh; Xu, Li

2015-01-01

Molten salt receivers play an important role in converting solar energy to thermal energy in concentrating solar power plants. This paper describes a dynamic mathematical model of the molten salt cavity receiver that couples the conduction, convection and radiation heat transfer processes in the receiver. The temperature dependence of the material properties is also considered. The radiosity method is used to calculate the radiation heat transfer inside the cavity. The outlet temperature of the receiver is calculated for 11 sets of transient working conditions. The simulation results compare well with experimental data, thus the model can be further used in system simulations of entire power plants. - Highlights: • A detailed model for molten salt cavity receiver is presented. • The model couples the conduction, convection and thermal radiation. • The simulation results compare well with experimental data. • The model can be further used for many purposes.

Tesla's coherent plasma discharge -and- a plan for megavolts at Megahertz

International Nuclear Information System (INIS)

Nichson, J.D.

1987-01-01

In his lecture on Experiments With Alternate Currents of High Potential and High Frequency before the Institute of Electrical Engineers in London (1892), Tesla reports a discharge through a partially evacuated air tube of 1 meter length and 1 inch diameter. It is characterized by the following properties: (1) The filamentary discharge may be locally displaced by a nearby dielectric body or a magnet. (2) When the filament is released, it demonstrates behaviour similar to that of a string which suspends a weight, including the formation of standing waves with distinct nodes. (3) Its decay time is on the order of 8 minutes. (4) The vibrating filament may be split with a magnet to produce two vibrating filaments. (5) This effect could only be formed with a dynamo-driven coil at low air pressures in the tube. The disruptive discharge coil (coloquially a Tesla Coil) failed to produce the effect with its superior voltage and frequency range. It is here proposed that this phenomenon is related to positive leader formation. A model for this, consistent for AC and DC discharges, is advanced. Also, a novel method for regulation of a nitrogen-filled spark gap will be proposed. It is hoped that this new device will produce smooth, uniform discharges from the Tesla Coil. This, if theory is correct on many points, will reproduce Tesla's coherent plasma at higher pressures in free-standing form, and will allow other novel effects

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...

Mirror-smooth surfaces and repair of defects in superconducting RF cavities by mechanical polishing

Energy Technology Data Exchange (ETDEWEB)

Cooper, C. A. [Fermilab; Cooley, L. D. [Fermilab

2012-11-22

Mechanical techniques for polishing the inside surface of niobium superconducting radio-frequency (SRF) cavities have been systematically explored. By extending known techniques to fine polishing, mirror-like finishes were produced, with <15 nm RMS (root mean square) roughness over 1 mm2 scan area. This is an order of magnitude less than the typical roughness produced by the electropolishing of niobium cavities. The extended mechanical polishing (XMP) process was applied to several SRF cavities which exhibited equator defects that caused quench at <20 MV m-1 and were not improved by further electropolishing. Cavity optical inspection equipment verified the complete removal of these defects, and minor acid processing, which dulled the mirror finish, restored performance of the defective cells to the high gradients and quality factors measured for adjacent cells when tested with other harmonics. This innate repair feature of XMP could be used to increase manufacturing yield. Excellent superconducting properties resulted after initial process optimization, with quality factor Q of 3 × 1010 and accelerating gradient of 43 MV m-1 being attained for a single-cell TESLA cavity, which are both close to practical limits. Several repaired nine-cell cavities also attained Q > 8 × 109 at 35 MV m-1, which is the specification for the International Linear Collider. Future optimization of the process and pathways for eliminating requirements for acid processing are also discussed.

Development of a 1.0 MV 100 Hz compact tesla transformer with PFL

International Nuclear Information System (INIS)

Kang Qiang; Chang Anbi; Li Mingjia; Meng Fanbao; Su Youbin

2006-01-01

The theory and characteristic of a compact Tesla transformer are introduced, and an unitized configuration design is performed for 1.0 MV, 100 Hz Tesla transformer and 40 Ω, 40 ns pulse forming line (PFL). Two coaxial open cores in Tesla transformer serve as the inner and outer conductors of PFL, and a traditional PFL is combined with the Tesla transformer, then the pulse generator can be smaller, more efficient, and more stable. The designed compact Tesla transformer employed in electron beams accelerator CHP01 can charge PFL of 600 pF for 1.3 MV voltage at a single shot, and keep 1.15 MV at 100 Hz repeated rates. Furthermore, a continuance run in 5 seconds is achieved by Tesla transformer under voltage and frequency ratings. (authors)

CavityPlus: a web server for protein cavity detection with pharmacophore modelling, allosteric site identification and covalent ligand binding ability prediction.

Science.gov (United States)

Xu, Youjun; Wang, Shiwei; Hu, Qiwan; Gao, Shuaishi; Ma, Xiaomin; Zhang, Weilin; Shen, Yihang; Chen, Fangjin; Lai, Luhua; Pei, Jianfeng

2018-05-10

CavityPlus is a web server that offers protein cavity detection and various functional analyses. Using protein three-dimensional structural information as the input, CavityPlus applies CAVITY to detect potential binding sites on the surface of a given protein structure and rank them based on ligandability and druggability scores. These potential binding sites can be further analysed using three submodules, CavPharmer, CorrSite, and CovCys. CavPharmer uses a receptor-based pharmacophore modelling program, Pocket, to automatically extract pharmacophore features within cavities. CorrSite identifies potential allosteric ligand-binding sites based on motion correlation analyses between cavities. CovCys automatically detects druggable cysteine residues, which is especially useful to identify novel binding sites for designing covalent allosteric ligands. Overall, CavityPlus provides an integrated platform for analysing comprehensive properties of protein binding cavities. Such analyses are useful for many aspects of drug design and discovery, including target selection and identification, virtual screening, de novo drug design, and allosteric and covalent-binding drug design. The CavityPlus web server is freely available at http://repharma.pku.edu.cn/cavityplus or http://www.pkumdl.cn/cavityplus.

Nikola Tesla and robotics

Directory of Open Access Journals (Sweden)

Vukobratović Miomir

2006-01-01

Full Text Available The paper analyzes some of Tesla's works and his most remarkable views concerning the problem of formulating theoretical bases of automatic control. As a tribute to Tesla's work on remote control of automated systems, as well to his (at the time far-seeing visions, special attention is paid to solving complex problem of control and feedback application. A more detailed discussion of the way and origin of formulating theoretical bases of automatic control are given. Besides, in more detail are presented the related pioneering works of Professor Nicholas Bernstein, great Russian physiologist who formulated the basic rules of the self-regulating movements of the man. Bernstein has achievements of highest scientific significance that has been in a direct function of identifying and proving the priority of his pioneering contributions in the domain of feedback, i.e. control and principles of cybernetics.

Spherical and cylindrical cavity expansion models based prediction of penetration depths of concrete targets.

Directory of Open Access Journals (Sweden)

Xiaochao Jin

Full Text Available The cavity expansion theory is most widely used to predict the depth of penetration of concrete targets. The main purpose of this work is to clarify the differences between the spherical and cylindrical cavity expansion models and their scope of application in predicting the penetration depths of concrete targets. The factors that influence the dynamic cavity expansion process of concrete materials were first examined. Based on numerical results, the relationship between expansion pressure and velocity was established. Then the parameters in the Forrestal's formula were fitted to have a convenient and effective prediction of the penetration depth. Results showed that both the spherical and cylindrical cavity expansion models can accurately predict the depth of penetration when the initial velocity is lower than 800 m/s. However, the prediction accuracy decreases with the increasing of the initial velocity and diameters of the projectiles. Based on our results, it can be concluded that when the initial velocity is higher than the critical velocity, the cylindrical cavity expansion model performs better than the spherical cavity expansion model in predicting the penetration depth, while when the initial velocity is lower than the critical velocity the conclusion is quite the contrary. This work provides a basic principle for selecting the spherical or cylindrical cavity expansion model to predict the penetration depth of concrete targets.

A 4 Tesla/1 meter superferric MRI magnet

International Nuclear Information System (INIS)

Schmidt, W.M.; Huson, F.R.; Mackay, W.W.; Rocha, R.M.

1991-01-01

Superferric technology was first applied to Magnetic Resonance Imaging (MRI) magnets by the Texas Accelerator Center (TAC) in 1986 with the design and construction of a 4 Tesla/30 cm magnet. In an evolutionary step, this technology is now being applied to the development of a whole body 4 Tesla/1 meter superconducting magnet. The design of such a magnetis presented in this paper

76 FR 60124 - Tesla Motors, Inc.; Grant of Petition for Temporary Exemption From the Electronic Stability...

Science.gov (United States)

2011-09-28

...-0110] Tesla Motors, Inc.; Grant of Petition for Temporary Exemption From the Electronic Stability... notice grants the petition of Tesla Motors, Inc. (Tesla) for the temporary exemption of its Roadster... procedures in 49 CFR Part 555, Tesla Motors, Inc. (Tesla) submitted a petition dated June 7, 2011 asking the...

TeSLA e-assessment workshop

NARCIS (Netherlands)

Janssen, José

2016-01-01

Presentatie ten behoeve van de e-assessment workshop voor docenten van de Open Universiteit Nederland betrokken in de eerste TeSLA pilot. Topics: toetsfraude, toetsdesign, technologie voor authenticatie en verificatie van auteurschap.

Temperature dependence of the hydrated electron's excited-state relaxation. I. Simulation predictions of resonance Raman and pump-probe transient absorption spectra of cavity and non-cavity models

Science.gov (United States)

Zho, Chen-Chen; Farr, Erik P.; Glover, William J.; Schwartz, Benjamin J.

2017-08-01

We use one-electron non-adiabatic mixed quantum/classical simulations to explore the temperature dependence of both the ground-state structure and the excited-state relaxation dynamics of the hydrated electron. We compare the results for both the traditional cavity picture and a more recent non-cavity model of the hydrated electron and make definite predictions for distinguishing between the different possible structural models in future experiments. We find that the traditional cavity model shows no temperature-dependent change in structure at constant density, leading to a predicted resonance Raman spectrum that is essentially temperature-independent. In contrast, the non-cavity model predicts a blue-shift in the hydrated electron's resonance Raman O-H stretch with increasing temperature. The lack of a temperature-dependent ground-state structural change of the cavity model also leads to a prediction of little change with temperature of both the excited-state lifetime and hot ground-state cooling time of the hydrated electron following photoexcitation. This is in sharp contrast to the predictions of the non-cavity model, where both the excited-state lifetime and hot ground-state cooling time are expected to decrease significantly with increasing temperature. These simulation-based predictions should be directly testable by the results of future time-resolved photoelectron spectroscopy experiments. Finally, the temperature-dependent differences in predicted excited-state lifetime and hot ground-state cooling time of the two models also lead to different predicted pump-probe transient absorption spectroscopy of the hydrated electron as a function of temperature. We perform such experiments and describe them in Paper II [E. P. Farr et al., J. Chem. Phys. 147, 074504 (2017)], and find changes in the excited-state lifetime and hot ground-state cooling time with temperature that match well with the predictions of the non-cavity model. In particular, the experiments

MODERN ELECTRIC CARS OF TESLA MOTORS COMPANY

OpenAIRE

O. F. Vynakov; E. V. Savolova; A. I. Skrynnyk

2016-01-01

This overview article shows the advantages of a modern electric car as compared with internal combustion cars by the example of the electric vehicles of Tesla Motors Company. It (в смысле- статья) describes the history of this firm, provides technical and tactical characteristics of three modifications of electric vehicles produced by Tesla Motors. Modern electric cars are not less powerful than cars with combustion engines both in speed and acceleration amount. They are reliable, economical ...

A model of gas cavity breakup behind a blockage in fast breeder reactor subassembly geometry

International Nuclear Information System (INIS)

Fukuzawa, Y.

1980-05-01

A semi-empirical model has been developed to describe the transient behaviour of a gas cavity due to breakup behind a blockage in Liquid Metal Fast Breeder Reactor subassembly geometry. The main mechanisms assumed for gas cavity breakup in the present model are as follows: The gas cavity is broken up by the pressure fluctuation at the interface due to turbulence in the liquid. The centrifugal force on the liquid opposes breakup. The model is able to describe experimental results on the transient behaviour of a gas cavity due to breakup after the termination of gas injection. On the basis of the present model the residence time of a gas cavity behind a blockage in sodium is predicted and the dependence of the residence time on blockage size is discussed. (orig.) [de

Nikola Tesla: the Moon's rotation.

Science.gov (United States)

Tomić, A.; Jovanović, B. S.

1993-09-01

The review of three articles by N. Tesla, published in the year 1919 in the journal "Electrical experimenter" is given, with special reference to the astronomical contents and to circumstances in which they appeared.

A transparent model of the human scala tympani cavity.

Science.gov (United States)

Rebscher, S J; Talbot, N; Bruszewski, W; Heilmann, M; Brasell, J; Merzenich, M M

1996-01-01

A dimensionally accurate clear model of the human scala tympani has been produced to evaluate the insertion and position of clinically applied intracochlear electrodes for electrical stimulation. Replicates of the human scala tympani were made from low melting point metal alloy (LMA) and from polymethylmeth-acrylate (PMMA) resin. The LMA metal casts were embedded in blocks of epoxy and in clear silicone rubber. After removal of the metal alloy, a cavity was produced that accurately models the human scala tympani. Investment casting molds were made from the PMMA scala tympani casts to enable production of multiple LMA casts from which identical models were fabricated. Total dimensional distortion of the LMA casting process was less than 1% in length and 2% in diameter. The models have been successfully integrated into the design process for the iterative development of advanced intracochlear electrode arrays at UCSF. These fabrication techniques are applicable to a wide range of biomedical design problems that require modelling of visually obscured cavities.

Cortical microinfarcts detected in vivo on 3 tesla MRI : Clinical and radiological correlates

NARCIS (Netherlands)

Van Dalen, Jan Willem; Scuric, Eva E M; Van Veluw, Susanne J.; Caan, Matthan W A; Nederveen, Aart J.; Biessels, Geert Jan; Van Gool, Willem A.; Richard, Edo

2015-01-01

Background and Purpose-Cortical microinfarcts (CMIs) are a common postmortem finding associated with vascular risk factors, cognitive decline, and dementia. Recently, CMIs identified in vivo on 7 Tesla MRI also proved retraceable on 3 Tesla MRI. Methods-We evaluated CMIs on 3 Tesla MRI in a

Cortical microinfarcts detected in vivo on 3 Tesla MRI: clinical and radiological correlates

NARCIS (Netherlands)

Dalen, J.W. van; Scuric, E.E.; Veluw, S.J. van; Caan, M.W.; Nederveen, A.J.; Biessels, G.J.; Gool, W.A. van; Richard, E.

2015-01-01

BACKGROUND AND PURPOSE: Cortical microinfarcts (CMIs) are a common postmortem finding associated with vascular risk factors, cognitive decline, and dementia. Recently, CMIs identified in vivo on 7 Tesla MRI also proved retraceable on 3 Tesla MRI. METHODS: We evaluated CMIs on 3 Tesla MRI in a

Undulator systems for the TESLA X-FEL

International Nuclear Information System (INIS)

Pflueger, J.; Tischer, M.

2002-01-01

A large X-ray FEL lab is under consideration within the TESLA project and is supposed to be operated in parallel with the TESLA linear collider. There will be five SASE FELs and five conventional spontaneous undulators. A conceptual design study has been made for the undulator systems for these X-FELs. It includes segmentation into 6.1 m long undulator 'cells'. Each consists of a 5 m long undulator 'segment', a separate quadrupole, one horizontal and one vertical corrector, and a phase shifter. These items are presented and discussed

Energy Spread Sources in TESLA and TTF

International Nuclear Information System (INIS)

Mosnier, A.; Tessier, J.M.

1995-03-01

The beam energy spread in the TESLA linac must be small enough to limit the emittance dilution due to the dispersive effects. This report summarizes the major sources of energy spread both for the TESLA linac and the TTF linac, where these estimations will be carefully checked with beam experiments. The first part recalls the intra-bunch energy spread while the second part looks into the bunch-to-bunch energy spread induced by rf field fluctuations within the bunch train and from pulse-to-pulse. (author). 3 refs., 4 figs

Radiation protection systems on the TESLA Accelerator Installation

International Nuclear Information System (INIS)

Pavlovic, R.

1996-01-01

In the Institute of Nuclear sciences VINCA, the Accelerator Installation TESLA which is an medium energy ion accelerator facility consisting of an isochronous cyclotron VINCY, a heavy ion source, a D/H ion source, three low energy and five high energy experimental channels is now under construction. Some problems in defining radiation protection and safety programme, particularly problems in construction appropriate shielding barriers at the Accelerator Installation TESLA are discussed in this paper. (author

Strategic Alliance with Competitors in the Electric Vehicle Market: Tesla Motor’s Case

Directory of Open Access Journals (Sweden)

Taesu Cheong

2016-01-01

Full Text Available We investigate how the choice of coopetition of the simultaneous pursuit of collaboration and competition dynamically impacts both the participating firms and also the other self-developing ones in the same market. A conceptual framework of mathematical models obtained from the arguments and insights in the literature is used to undertake an in-depth study through a multiperiod analysis from 2013 to 2020 of an exemplar case of coopetition, the two concurrently ongoing coopetition partnerships in the US electric vehicle (EV market, the Tesla Motors-Daimler AG alliance and the Tesla Motors-Toyota alliance and the other firms which are not involved in coopetition.

Cavity Formation Modeling of Fiber Fuse in Single-Mode Optical Fibers

Directory of Open Access Journals (Sweden)

Yoshito Shuto

2017-01-01

Full Text Available The evolution of a fiber-fuse phenomenon in a single-mode optical fiber was studied theoretically. To clarify both the silica-glass densification and cavity formation, which have been observed in fiber fuse propagation, we investigated a nonlinear oscillation model using the Van Der Pol equation. This model was able to phenomenologically explain both the densification of the core material and the formation of periodic cavities in the core layer as a result of a relaxation oscillation.

Activities on cryostats and SRF cavities at the I.P.N. Orsay laboratory

International Nuclear Information System (INIS)

Buelher, S.; Caruette, A.; Fouaidy, M.; Junquera, T.

1993-01-01

The main effort of the SRF community at Orsay during the last five years was concentrated on the MACSE project (study, construction, assembly and test of 3 cryostats), participation to the TESLA project and R and D activities in close collaboration with the Saclay SRF group. 3 major topics are outlined and briefly discussed: cryogenics, scanning surface thermometers for diagnostics on SRF cavities and thermal behaviour analysis of HOM couplers. The main results obtained in this frame since the 5th SC workshop at Hamburg in 1991 are presented. (authors) 12 refs., 17 figs., 6 tabs

77 FR 22383 - Petition for Exemption From the Federal Motor Vehicle Motor Theft Prevention Standard; TESLA

Science.gov (United States)

2012-04-13

... From the Federal Motor Vehicle Motor Theft Prevention Standard; TESLA AGENCY: National Highway Traffic... exemption. SUMMARY: This document grants in full the petition of Tesla Motors Inc's. (Tesla) for an... 49 CFR Part 541, Federal Motor Vehicle Theft Prevention Standard. Tesla requested confidential...

Design of an 18 Tesla, tandem mirror, fusion reactor, hybrid choke coil

International Nuclear Information System (INIS)

Parmer, J.F.; Agarwal, K.; Gurol, H.; Mancuso, A.; Michels, P.H.; Peck, S.D.; Burgeson, J.; Dalder, E.N.

1987-01-01

A hybrid, part normal part superconducting 18-Tesla solenoid choke coil is designed for a tandem mirror fusion reactor. The present state of the art is represented by the 12-Tesla, superconducting NbSn coil. Future applications other than tandem mirror fusion devices needing high field solenoids might require hybrid magnets of the type described herein. The hybrid design was generated because of critical field performance limitations on present, practical superconducting wires. A hybrid design might be required (due to structural limits) even if the critical field were higher. Also, hybrids could be a cost-effective way of getting very high fields for certain applications. The 18-Tesla solenoid described is composed of an inner coil made of water-cooled, high-strength zirconium copper which generates 3 Tesla. A superconducting NbSn background coil contributes the remaining 15 Tesla. The focus of the design study was on the inner coil. Demonstration fabrication and testing was performed

Optimization of materials for the parts that compose a Tesla turbine

International Nuclear Information System (INIS)

Rocha, Geovana Vilas Boas da; Guimaraes, Lamartine N.F.; Placco, Guilherme M.

2013-01-01

The TERRA project (Tecnologia de Reatores Rapidos Avancados) of the Aeronautica (Brazil) aims to develop the necessary technologies for the design of nuclear microreactors. These, in turn, aim to address the thermal and electrical needs in space vehicles. One of the activities of this project is to build a closed thermal cycle, the Rankine type in order to test a Tesla turbine type developed by the group. In this thermodynamic cycle the water is transformed into steam, which triggers a turbine which, in turn, provide power to the alternator to be converted into electricity. The work presented a survey of the materials available on the national market for machining a Tesla type turbine. The surveys were made considering the characteristics and operating conditions of a specific thermal cycle, the interest of the group. Results: cost-benefit tables for each party of the turbine, characteristics of each material, the machining process, as well as a comparison between one of 304L stainless steel model turbine with a turbine with the selected materials. The results from this study raised the level of sophistication of the research involved the TERRA project, since the study of ideal materials that make up the parts of a Tesla type turbine in a heat cycle is unprecedented

Imaging of patients with hippocampal sclerosis at 7 Tesla: initial results.

Science.gov (United States)

Breyer, Tobias; Wanke, Isabel; Maderwald, Stefan; Woermann, Friedrich G; Kraff, Oliver; Theysohn, Jens M; Ebner, Alois; Forsting, Michael; Ladd, Mark E; Schlamann, Marc

2010-04-01

Focal epilepsies potentially can be cured by neurosurgery; other treatment options usually remain symptomatic. High-resolution magnetic resonance (MR) imaging is the central imaging strategy in the evaluation of focal epilepsy. The most common substrate of temporal epilepsies is hippocampal sclerosis (HS), which cannot always be sufficiently characterized with current MR field strengths. Therefore, the purpose of our study was to demonstrate the feasibility of high-resolution MR imaging at 7 Tesla in patients with focal epilepsy resulting from a HS and to improve image resolution at 7 Tesla in patients with HS. Six patients with known HS were investigated with T1-, T2-, T2(*)-, and fluid-attenuated inversion recovery-weighted sequences at 7 Tesla with an eight-channel transmit-receive head coil. Total imaging time did not exceed 90 minutes per patient. High-resolution imaging at 7 Tesla is feasible and reveals high resolution of intrahippocampal structures in vivo. HS was confirmed in all patients. The maximum non-interpolated in-plane resolution reached 0.2 x 0.2 mm(2) in T2(*)-weighted images. The increased susceptibility effects at 7 Tesla revealed identification of intrahippocampal structures in more detail than at 1.5 Tesla, but otherwise led to stronger artifacts. Imaging revealed regional differences in hippocampal atrophy between patients. The scan volume was limited because of specific absorption rate restrictions, scanning time was reasonable. High-resolution imaging at 7 Tesla is promising in presurgical epilepsy imaging. "New" contrasts may further improve detection of even very small intrahippocampal structural changes. Therefore, further investigations will be necessary to demonstrate the potential benefit for presurgical selection of patients with various lesion patterns in mesial temporal epilepsies resulting from a unilateral HS. Copyright 2010 AUR. Published by Elsevier Inc. All rights reserved.

Optic Nerve Assessment Using 7-Tesla Magnetic Resonance Imaging.

Science.gov (United States)

Singh, Arun D; Platt, Sean M; Lystad, Lisa; Lowe, Mark; Oh, Sehong; Jones, Stephen E; Alzahrani, Yahya; Plesec, Thomas

2016-04-01

The purpose of this study was to correlate high-resolution magnetic resonance imaging (MRI) and histologic findings in a case of juxtapapillary choroidal melanoma with clinical evidence of optic nerve invasion. With institutional review board approval, an enucleated globe with choroidal melanoma and optic nerve invasion was imaged using a 7-tesla MRI followed by histopathologic evaluation. Optical coherence tomography, B-scan ultrasonography, and 1.5-tesla MRI of the orbit (1-mm sections) could not detect optic disc invasion. Ex vivo, 7-tesla MRI detected optic nerve invasion, which correlated with histopathologic features. Our case demonstrates the potential to document the existence of optic nerve invasion in the presence of an intraocular tumor, a feature that has a major bearing on decision making, particularly for consideration of enucleation.

[Examination of upper abdominal region in high spatial resolution diffusion-weighted imaging using 3-Tesla MRI].

Science.gov (United States)

Terada, Masaki; Matsushita, Hiroki; Oosugi, Masanori; Inoue, Kazuyasu; Yaegashi, Taku; Anma, Takeshi

2009-03-20

The advantage of the higher signal-to-noise ratio (SNR) of 3-Tesla magnetic resonance imaging (3-Tesla) has the possibility of contributing to the improvement of high spatial resolution without causing image deterioration. In this study, we compared SNR and the apparent diffusion coefficient (ADC) value with 3-Tesla as the condition in the diffusion-weighted image (DWI) parameter of the 1.5-Tesla magnetic resonance imaging (1.5-Tesla) and we examined the high spatial resolution images in the imaging method [respiratory-triggering (RT) method and breath free (BF) method] and artifact (motion and zebra) in the upper abdominal region of DWI at 3-Tesla. We have optimized scan parameters based on phantom and in vivo study. As a result, 3-Tesla was able to obtain about 1.5 times SNR in comparison with the 1.5-Tesla, ADC value had few differences. Moreover, the RT method was effective in correcting the influence of respiratory movement in comparison with the BF method, and image improvement by the effective acquisition of SNR and reduction of the artifact were provided. Thus, DWI of upper abdominal region was a useful sequence for the high spatial resolution in 3-Tesla.

Nikola Tesla Educational Opportunity School.

Science.gov (United States)

Design Cost Data, 2001

2001-01-01

Describes the architectural design, costs, general description, and square footage data for the Nikola Tesla Educational Opportunity School in Colorado Springs, Colorado. A floor plan and photos are included along with a list of manufacturers and suppliers used for the project. (GR)

MRI of the carotid artery at 7 Tesla: Quantitative comparison with 3 Tesla

NARCIS (Netherlands)

Koning, Wouter; De Rotte, Alexandra A J; Bluemink, Johanna J.; Van Der Velden, Tijl A.; Luijten, Peter R.; Klomp, DWJ; Zwanenburg, Jaco J M

2015-01-01

Purpose: To evaluate the 7 Tesla (T) MRI of the carotid arteries, as quantitatively compared with 3T. Materials and Methods: The 7T MRI of the carotid arteries was performed in six healthy subjects and in two patients with carotid stenosis. The healthy group was scanned at 3T and at 7T, using

76 FR 47639 - Tesla Motors, Inc.; Receipt of Petition for Temporary Exemption From the Electronic Stability...

Science.gov (United States)

2011-08-05

...-0110] Tesla Motors, Inc.; Receipt of Petition for Temporary Exemption From the Electronic Stability... accordance with the procedures in 49 CFR part 555, Tesla Motors, Inc., has petitioned the agency for a... part 555, Tesla Motors, Inc. (Tesla) submitted a petition dated June 7, 2001 asking the agency for a...

Using 3 Tesla magnetic resonance imaging in the pre-operative evaluation of tongue carcinoma.

Science.gov (United States)

Moreno, K F; Cornelius, R S; Lucas, F V; Meinzen-Derr, J; Patil, Y J

2017-09-01

This study aimed to evaluate the role of 3 Tesla magnetic resonance imaging in predicting tongue tumour thickness via direct and reconstructed measures, and their correlations with corresponding histological measures, nodal metastasis and extracapsular spread. A prospective study was conducted of 25 patients with histologically proven squamous cell carcinoma of the tongue and pre-operative 3 Tesla magnetic resonance imaging from 2009 to 2012. Correlations between 3 Tesla magnetic resonance imaging and histological measures of tongue tumour thickness were assessed using the Pearson correlation coefficient: r values were 0.84 (p Tesla magnetic resonance imaging had 83 per cent sensitivity, 82 per cent specificity, 82 per cent accuracy and a 90 per cent negative predictive value for detecting cervical lymph node metastasis. In this cohort, 3 Tesla magnetic resonance imaging measures of tumour thickness correlated highly with the corresponding histological measures. Further, 3 Tesla magnetic resonance imaging was an effective method of detecting malignant adenopathy with extracapsular spread.

Two-Layer 16 Tesla Cosθ Dipole Design for the FCC

Energy Technology Data Exchange (ETDEWEB)

Holik, Eddie Frank [Fermilab; Ambrosio, Giorgio [Fermilab; Apollinari, G. [Fermilab

2018-02-13

The Future Circular Collider or FCC is a study aimed at exploring the possibility to reach 100 TeV total collision energy which would require 16 tesla dipoles. Upon the conclusion of the High Luminosity Upgrade, the US LHC Accelerator Upgrade Pro-ject in collaboration with CERN will have extensive Nb3Sn magnet fabrication experience. This experience includes robust Nb3Sn conductor and insulation scheming, 2-layer cos2θ coil fabrication, and bladder-and-key structure and assembly. By making im-provements and modification to existing technology the feasibility of a two-layer 16 tesla dipole is investigated. Preliminary designs indicate that fields up to 16.6 tesla are feasible with conductor grading while satisfying the HE-LHC and FCC specifications. Key challenges include accommodating high-aspect ratio conductor, narrow wedge design, Nb3Sn conductor grading, and especially quench protection of a 16 tesla device.

MRI safety of a programmable shunt assistant at 3 and 7 Tesla.

Science.gov (United States)

Mirzayan, M Javad; Klinge, Petra M; Samii, Madjid; Goetz, Friedrich; Krauss, Joachim K

2012-06-01

Several new shunt technologies have been developed to optimize hydrocephalus treatment within the past few years. Overdrainage, however, still remains an unresolved problem. One new technology which may reduce the frequency of this complication is the use of a programmable shunt assistant (proSA). Inactive in a horizontal position, it impedes CSF flow in a vertical position according to a prescribed pressure level ranging from 0 to 40 cm H(2)O. We exposed the proSA valve in an ex vivo protocol to MR systems operating at 3 and 7 Tesla to investigate its MRI safety. Following 3 Tesla exposure, no changes in valve settings were noted. Adjustment to any pressure level was possible thereafter. The mean deflection angle was 23 ± 3°. After exposure to 7 Tesla, however, there were unintended pressure changes, and the mechanism for further adjustment of the valves even disintegrated. According to the results of this study, proSA is safe with heteropolar vertical magnet alignment at 3 Tesla. Following 7 Tesla exposure, the valves lost their functional capability.

Assessing the MR compatibility of dental retainer wires at 7 Tesla.

Science.gov (United States)

Wezel, Joep; Kooij, Bert Jan; Webb, Andrew G

2014-10-01

To determine the MR compatibility of common dental retainer wires at 7 Tesla in terms of potential RF heating and magnetic susceptibility effects. Electromagnetic simulations and experimental results were compared for dental retainer wires placed in tissue-mimicking phantoms. Simulations were then performed for a human model with wire in place. Finally, image quality was assessed for different scanning protocols and wires. Simulations and experimental data in phantoms agreed well, with the length of the wire correlating to maximum heating in phantoms being approximately 47 mm. Even in this case, no substantial heating occurs when scanning within the specific absorption rate (SAR) guidelines for the head. Image distortions from the most ferromagnetic dental wire were not significant for any brain region. Dental retainer wires appear to be MR compatible at 7 Tesla. Copyright © 2013 Wiley Periodicals, Inc.

Modelling of shrinkage cavity defects during the wheel and belt casting process

International Nuclear Information System (INIS)

Dablement, S; Mortensen, D; Fjaer, H; Lee, M; Grandfield, J; Savage, G; Nguyen, V

2012-01-01

Properzi continuous casting is a wheel and belt casting process used for producing aluminium wire rod which is essential to the making of electrical cables and over head lines. One of the main concerns of Properzi process users is to ensure good quality of the final product and to avoid cast defects especially the presence of shrinkage cavity. Numerical models developed with the Alsim software, which allows an automatic calculation of gap dependent heat transfer coefficients at the metal-mould interface due to thermal deformation, are used in order to get a better understanding on the shrinkage cavity formation. Models show the effect of process parameters on the cavity defect development and provide initial guidance for users in order to avoid this kind of casting defect.

Self-consistent Maxwell-Bloch model of quantum-dot photonic-crystal-cavity lasers

Science.gov (United States)

Cartar, William; Mørk, Jesper; Hughes, Stephen

2017-08-01

We present a powerful computational approach to simulate the threshold behavior of photonic-crystal quantum-dot (QD) lasers. Using a finite-difference time-domain (FDTD) technique, Maxwell-Bloch equations representing a system of thousands of statistically independent and randomly positioned two-level emitters are solved numerically. Phenomenological pure dephasing and incoherent pumping is added to the optical Bloch equations to allow for a dynamical lasing regime, but the cavity-mediated radiative dynamics and gain coupling of each QD dipole (artificial atom) is contained self-consistently within the model. These Maxwell-Bloch equations are implemented by using Lumerical's flexible material plug-in tool, which allows a user to define additional equations of motion for the nonlinear polarization. We implement the gain ensemble within triangular-lattice photonic-crystal cavities of various length N (where N refers to the number of missing holes), and investigate the cavity mode characteristics and the threshold regime as a function of cavity length. We develop effective two-dimensional model simulations which are derived after studying the full three-dimensional passive material structures by matching the cavity quality factors and resonance properties. We also demonstrate how to obtain the correct point-dipole radiative decay rate from Fermi's golden rule, which is captured naturally by the FDTD method. Our numerical simulations predict that the pump threshold plateaus around cavity lengths greater than N =9 , which we identify as a consequence of the complex spatial dynamics and gain coupling from the inhomogeneous QD ensemble. This behavior is not expected from simple rate-equation analysis commonly adopted in the literature, but is in qualitative agreement with recent experiments. Single-mode to multimode lasing is also observed, depending on the spectral peak frequency of the QD ensemble. Using a statistical modal analysis of the average decay rates, we also

77 FR 2269 - Foreign-Trade Zone 18-San Jose, CA, Application for Subzone, Tesla Motors, Inc. (Electric...

Science.gov (United States)

2012-01-17

..., CA, Application for Subzone, Tesla Motors, Inc. (Electric Passenger Vehicles), Palo Alto and Fremont... passenger- vehicle manufacturing facilities of Tesla Motors, Inc. (Tesla), located in Palo Alto and Fremont... January 10, 2012. The Tesla facilities (currently employing over 1,000 workers) consist of two sites: Site...

The cavity electromagnetic field within the polarizable continuum model of solvation

Energy Technology Data Exchange (ETDEWEB)

Pipolo, Silvio, E-mail: silvio.pipolo@nano.cnr.it [Center S3, CNR Institute of Nanoscience, Modena (Italy); Department of Physics, University of Modena and Reggio Emilia, Modena (Italy); Corni, Stefano, E-mail: stefano.corni@nano.cnr.it [Center S3, CNR Institute of Nanoscience, Modena (Italy); Cammi, Roberto, E-mail: roberto.cammi@unipr.it [Department of Chemistry, Università degli studi di Parma, Parma (Italy)

2014-04-28

Cavity field effects can be defined as the consequences of the solvent polarization induced by the probing electromagnetic field upon spectroscopies of molecules in solution, and enter in the definitions of solute response properties. The polarizable continuum model of solvation (PCM) has been extended in the past years to address the cavity-field issue through the definition of an effective dipole moment that couples to the external electromagnetic field. We present here a rigorous derivation of such cavity-field treatment within the PCM starting from the general radiation-matter Hamiltonian within inhomogeneous dielectrics and recasting the interaction term to a dipolar form within the long wavelength approximation. To this aim we generalize the Göppert-Mayer and Power-Zienau-Woolley gauge transformations, usually applied in vacuo, to the case of a cavity vector potential. Our derivation also allows extending the cavity-field correction in the long-wavelength limit to the velocity gauge through the definition of an effective linear momentum operator. Furthermore, this work sets the basis for the general PCM treatment of the electromagnetic cavity field, capable to describe the radiation-matter interaction in dielectric media beyond the long-wavelength limit, providing also a tool to investigate spectroscopic properties of more complex systems such as molecules close to large nanoparticles.

Characterizing cavities in model inclusion molecules: a comparative study.

Science.gov (United States)

Torrens, F; Sánchez-Marín, J; Nebot-Gil, I

1998-04-01

We have selected fullerene-60 and -70 cavities as model systems in order to test several methods for characterizing inclusion molecules. The methods are based on different technical foundations such as a square and triangular tessellation of the molecule taken as a unitary sphere, spherical tessellation of the molecular surface, numerical integration of the atomic volumes and surfaces, triangular tessellation of the molecular surface, and a cubic lattice approach to a molecular space. Accurate measures of the molecular volume and surface area have been performed with the pseudo-random Monte Carlo (MCVS) and uniform Monte Carlo (UMCVS) methods. These calculations serve as a reference for the rest of the methods. The SURMO2 and MS methods have not recognized the cavities and may not be convenient for intercalation compounds. The programs that have detected the cavities never exceed 5% deviation relative to the reference values for molecular volume and surface area. The GEPOL algorithm, alone or combined with TOPO, shows results in good agreement with those of the UMCVS reference. The uniform random number generator provides the fastest convergence for UMCVS and a correct estimate of the standard deviations. The effect of the internal cavity on the accessible surfaces has been calculated.

Characterizing Cavities in Model Inclusion Fullerenes: A Comparative Study

Directory of Open Access Journals (Sweden)

Francisco Torrens

2001-06-01

Full Text Available Abstract: The fullerene-82 cavity is selected as a model system in order to test several methods for characterizing inclusion molecules. The methods are based on different technical foundations such as a square and triangular tessellation of the molecular surface, spherical tessellation of the molecular surface, numerical integration of the atomic volumes and surfaces, triangular tessellation of the molecular surface, and cubic lattice approach to the molecular volume. Accurate measures of the molecular volume and surface area have been performed with the pseudorandom Monte Carlo (MCVS and uniform Monte Carlo (UMCVS methods. These calculations serve as a reference for the rest of the methods. The SURMO2 method does not recognize the cavity and may not be convenient for intercalation compounds. The programs that detect the cavities never exceed 1% deviation relative to the reference value for molecular volume and 5% for surface area. The GEPOL algorithm, alone or combined with TOPO, shows results in good agreement with those of the UMCVS reference. The uniform random number generator provides the fastest convergence for UMCVS and a correct estimate of the standard deviations. The effect of the internal cavity on the solvent-accessible surfaces has been calculated. Fullerene-82 is compared with fullerene-60 and -70.

A comparative Thermal Analysis of conventional parabolic receiver tube and Cavity model tube in a Solar Parabolic Concentrator

Science.gov (United States)

Arumugam, S.; Ramakrishna, P.; Sangavi, S.

2018-02-01

Improvements in heating technology with solar energy is gaining focus, especially solar parabolic collectors. Solar heating in conventional parabolic collectors is done with the help of radiation concentration on receiver tubes. Conventional receiver tubes are open to atmosphere and loose heat by ambient air currents. In order to reduce the convection losses and also to improve the aperture area, we designed a tube with cavity. This study is a comparative performance behaviour of conventional tube and cavity model tube. The performance formulae were derived for the cavity model based on conventional model. Reduction in overall heat loss coefficient was observed for cavity model, though collector heat removal factor and collector efficiency were nearly same for both models. Improvement in efficiency was also observed in the cavity model’s performance. The approach towards the design of a cavity model tube as the receiver tube in solar parabolic collectors gave improved results and proved as a good consideration.

Cervical external immobilization devices: evaluation of magnetic resonance imaging issues at 3.0 Tesla.

Science.gov (United States)

Diaz, Francis L; Tweardy, Lisa; Shellock, Frank G

2010-02-15

Laboratory investigation, ex vivo. Currently, no studies have addressed the magnetic resonance imaging (MRI) issues for cervical external immobilization devices at 3-Tesla. Under certain conditions significant heating may occur, resulting in patient burns. Furthermore, artifacts can be substantial and prevent the diagnostic use of MRI. Therefore, the objective of this investigation was to evaluate MRI issues for 4 different cervical external immobilization devices at 3-Tesla. Excessive heating and substantial artifacts are 2 potential complications associated with performing MRI at 3-Tesla in patients with cervical external immobilization devices. Using ex vivo testing techniques, MRI-related heating and artifacts were evaluated for 4 different cervical devices during MRI at 3-Tesla. Four cervical external immobilization devices (Generation 80, Resolve Ring and Superstructure, Resolve Ring and Jerome Vest/Jerome Superstructure, and the V1 Halo System; Ossur Americas, Aliso Viejo, CA) underwent MRI testing at 3-Tesla. All devices were made from nonmetallic or nonmagnetic materials. Heating was determined using a gelled-saline-filled skull phantom with fluoroptic thermometry probes attached to the skull pins. MRI was performed at 3-Tesla, using a high level of RF energy. Artifacts were assessed at 3-Tesla, using standard cervical imaging techniques. The Generation 80 and V1 Halo devices exhibited substantial temperature rises (11.6 degrees C and 8.5 degrees C, respectively), with "sparking" evident for the Generation 80 during the MRI procedure. Artifacts were problematic for these devices, as well. By comparison, the 2 Resolve Ring-based cervical external immobilization devices showed little or no heating (Tesla.

Ability of preoperative 3.0-Tesla magnetic resonance imaging to predict the absence of side-specific extracapsular extension of prostate cancer.

Science.gov (United States)

Hara, Tomohiko; Nakanishi, Hiroyuki; Nakagawa, Tohru; Komiyama, Motokiyo; Kawahara, Takashi; Manabe, Tomoko; Miyake, Mototaka; Arai, Eri; Kanai, Yae; Fujimoto, Hiroyuki

2013-10-01

Recent studies have shown an improvement in prostate cancer diagnosis with the use of 3.0-Tesla magnetic resonance imaging. We retrospectively assessed the ability of this imaging technique to predict side-specific extracapsular extension of prostate cancer. From October 2007 to August 2011, prostatectomy was carried out in 396 patients after preoperative 3.0-Tesla magnetic resonance imaging. Among these, 132 (primary sample) and 134 patients (validation sample) underwent 12-core prostate biopsy at the National Cancer Center Hospital of Tokyo, Japan, and at other institutions, respectively. In the primary dataset, univariate and multivariate analyses were carried out to predict side-specific extracapsular extension using variables determined preoperatively, including 3.0-Tesla magnetic resonance imaging findings (T2-weighted and diffusion-weighted imaging). A prediction model was then constructed and applied to the validation study sample. Multivariate analysis identified four significant independent predictors (P Tesla diffusion-weighted magnetic resonance imaging findings, ≥2 positive biopsy cores on each side and a maximum percentage of positive cores ≥31% on each side. The negative predictive value was 93.9% in the combination model with these four predictors, meanwhile the positive predictive value was 33.8%. Good reproducibility of these four significant predictors and the combination model was observed in the validation study sample. The side-specific extracapsular extension prediction by the biopsy Gleason score and factors associated with tumor location, including a positive 3.0-Tesla diffusion-weighted magnetic resonance imaging finding, have a high negative predictive value, but a low positive predictive value. © 2013 The Japanese Urological Association.

The Legacy of Nikola Tesla

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 4. The Legacy of Nikola Tesla - AC Power System and its Growth in India. D P Sen Gupta. General Article Volume 12 Issue 4 April 2007 pp 69-79. Fulltext. Click here to view fulltext PDF. Permanent link:

Modelling Wireless Power Transfer Using an Array of Tesla Coils

Science.gov (United States)

Pierson, Casey Thomas

Wireless power transmission, or WPT, is a well-demonstrated property in electrical science and physics. Coil-and-wave transmission (CWT) consists of two Tesla coils, one powered by a controlled voltage source v src and one connected across a generic load Z 0 , at a mid- to long range distance apart with spherical capacitors at each of their top loads. The literature on the different methods of WPT varies widely, but research of CWT is sparse, lacking especially in the area of computer simulation. Recently, a physical experiment was conducted by Marzolf et al. in [1], and yielded surprising resonant frequencies in the high frequency range. The goal of this research is to answer the question of whether these reosnant frequencies originate in unexplained field effects or in non-ideal circuit behavior, and establish a formal model to indicate at what frequencies the resonant peaks occur as a first approximation. By carefully constructing a simulation of the most geometrically simple, power efficient design in the work of Marzolf et al. using the scientific software Octave, we investigate these frequencies computationally: first, an ideal scenario that has no flux leakage or exterior losses is modelled mathematically and simulated, and then, a non-ideal scenario that accounts for losses in the coils and surroundings is modelled mathematically and simulated. Both models utilize a simple formula for spherical capacitance for the top loads. After running these simulations through detailed sampling up to 4 MHz, the ideal model could not account for the resonant peaks, while the non-ideal model indicated the resonant peaks near the exact frequency ranges that were observed. An unexpected characteristic of these results was that coupling coefficients between the coils of the transmitter and receiver played a noticeable part in the indication of resonant peaks. This demonstrates that unknown field effects are not the primary driver of resonance in the ideal or non

Computer Aided Modeling of Human Mastoid Cavity Biomechanics Using Finite Element Analysis

Directory of Open Access Journals (Sweden)

Chou Yuan-Fang

2010-01-01

Full Text Available The aim of the present study was to analyze the human mastoid cavity on sound transmission using finite element method. Pressure distributions in the external ear canal and middle ear cavity at different frequencies were demonstrated. Our results showed that, first, blocking the aditus improves middle ear sound transmission in the 1500- to 2500-Hz range and decreases displacement in frequencies below 1000 Hz when compared with the normal ear. Second, at frequencies lower than 1000 Hz, the acoustic pressures were almost uniformly distributed in the external ear canal and middle ear cavity. At high frequencies, higher than 1000 Hz, the pressure distribution varied along the external ear canal and middle ear cavity. Third, opening the aditus, the pressures difference in dB between the middle ear cavity and external ear canal were larger than those of the closed mastoid cavity in low frequency (<1000 Hz. Finally, there was no significant difference in the acoustic pressure between the oval window and round window is noted and increased by 5 dB by blocking the aditus. These results suggest that our complete FE model including the mastoid cavity is potentially useful and can provide more information in the study of middle ear biomechanics.

The Legacy of Nikola Tesla

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 3. The Legacy of Nikola Tesla - The AC System that he Helped to Usher in. D P Sen Gupta. General Article Volume 12 Issue 3 March 2007 pp 54-69. Fulltext. Click here to view fulltext PDF. Permanent link:

Modeling the Rapid Boil-Off of a Cryogenic Liquid When Injected into a Low Pressure Cavity

Science.gov (United States)

Lira, Eric

2016-01-01

Many launch vehicle cryogenic applications require the modeling of injecting a cryogenic liquid into a low pressure cavity. The difficulty of such analyses lies in accurately predicting the heat transfer coefficient between the cold liquid and a warm wall in a low pressure environment. The heat transfer coefficient and the behavior of the liquid is highly dependent on the mass flow rate into the cavity, the cavity wall temperature and the cavity volume. Testing was performed to correlate the modeling performed using Thermal Desktop and Sinda Fluint Thermal and Fluids Analysis Software. This presentation shall describe a methodology to model the cryogenic process using Sinda Fluint, a description of the cryogenic test set up, a description of the test procedure and how the model was correlated to match the test results.

A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing

Directory of Open Access Journals (Sweden)

Mohammed-Baker Habhab

2016-11-01

Full Text Available Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications.

A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing.

Science.gov (United States)

Habhab, Mohammed-Baker; Ismail, Tania; Lo, Joe Fujiou

2016-11-23

Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications.

Temperature Structure of a Coronal Cavity

Science.gov (United States)

Kucera, T. A.; Gibson, S. E.; Schmit, D. J.

2011-01-01

we analyze the temperature structure of a coronal cavity observed in Aug. 2007. coronal cavities are long, low-density structures located over filament neutral lines and are often seen as dark elliptical features at the solar limb in white light, EUV and x-rays. when these structures erupt they form the cavity portions of CMEs. It is important to establish the temperature structure of cavities in order to understand the thermodynamics of cavities in relation to their three-dimensional magnetic structure. To analyze the temperature we compare temperature ratios of a series of iron lines observed by the Hinode/EUv Imaging spectrometer (EIS). We also use those lines to constrain a forward model of the emission from the cavity and streamer. The model assumes a coronal streamer with a tunnel-like cavity with elliptical cross-section and a Gaussian variation of height along the tunnel lenth. Temperature and density can be varied as a function of altitude both in the cavity and streamer. The general cavity morphology and the cavity and streamer density have already been modeled using data from STEREO's SECCHI/EUVI and Hinode/EIS (Gibson et al 2010 and Schmit & Gibson 2011).

Upgrading the power supplies of TEXTOR for three Tesla operation

International Nuclear Information System (INIS)

Giesen, B.; Veiders, E.; Petree, F.; Fink, R.; Wagnitz, R.

1986-01-01

The toroidal magnetic system of TEXTOR can tolerate a magnetic field load of up to 2.6 Tesla routinely at full plasma current, and of up to 3 Tesla under certain boundary conditions and for a restricted number of discharges. The original power supply which can generate a toroidal magnetic field of 2 Tesla has been upgraded to operate at a field strength of 3 Tesla, by adding a new, controlled rectifier, with its own independent control, connected in parallel with the first. Studies were undertaken to determine its behaviour where control is lost, such as when a circuit breaker trips or in ''freewheel'' operation. This paper analyzes this asymmetrical arrangement and discusses the danger of damaging the smaller unit by commutating a large current into it. Moreover, in order to improve the availability of TEXTOR, the new controlled rectifier is redundant to two other units that control the vertical field and the ohmic heating coil currents. For this purpose the two bridges of this 12-pulse system are to be changed from a parallel to a series connexion, the free-wheeling diodes are disconnected and redeployed to block the large voltage pulses that are induced at plasma initiation, and 3-phase ''freewheeling'' thyristors are added that serve to reduce reactive power consumption

TESLA accelerator installation

International Nuclear Information System (INIS)

Neskovic, N.; Ostojic, R.; Susini, A.; Milinkovic, Lj.; Ciric, D.; Dobrosavljevic, A.; Brajuskovic, B.; Cirkovic, S.; Bojovic, B.; Josipovic, M.

1992-01-01

The TESLA accelerator Installation is described. Its main parts are the VINCY Cyclotron, the multiply charged heavy-ion mVINIS Ion Source, and the negative light-ion pVINIS Ion Source. The Installation should be the principal installation of a regional center for basic and applied research in nuclear physics, atomic physics, surface physics and solid state physics, for production of radioisotopes, for research and therapy in nuclear medicine. The first extraction of the ion beam from the Cyclotron is planned for 1995. (R.P.) 3 refs.; 1 fig

Assessment of models for steam release from concrete and implications for modeling corium behavior in reactor cavities

International Nuclear Information System (INIS)

Washington, K.E.; Carroll, D.E.

1988-01-01

Models for concrete outgassing have been developed and incorporated into a developmental version of the CONTAIN code for the assessment of corium behavior in reactor cavities. The resultant code, referred to as CONTAIN/OR in order to distinguish it from the released version of CONTAIN, has the capability to model transient heat conduction and concrete outgassing in core-concrete interaction problems. This study focused on validation and assessment of the outgassing model through comparisons with other concrete response codes. In general, the model is not mechanistic; however, there are certain important processes and feedback effects that are treated rigorously. The CONTAIN outgassing model was compared against two mechanistic concrete response codes (USINT and SLAM). Gas release and temperature profile predictions for several concrete thicknesses and heating rates were performed with acceptable agreement seen in each case. The model was also applied to predict corium behavior in a reactor cavity for a hypothetical severe accident scenario. In this calculation, gases evolving from the concrete during nonablating periods fueled exothermic Zr chemical reactions in the corium. Higher corium temperatures and more concrete ablation were observed when compared with that seen when concrete outgassing was neglected. Even though this result depends somewhat upon the makeup of the corium sources and the concrete type in the cavity, it does show that concrete outgassing can be important in the modeling of corium behavior in reactor cavities. In particular, the need to expand the traditional role of CORCON from steady-state ablation to the consideration of more transient events is clearly evident as a result of this work. 5 refs., 11 figs., 1 tab

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

Electron scattering with polarized targets at TESLA

International Nuclear Information System (INIS)

Anselmino, M.; Aschenauer, E.C.; Belostotski, S.

2000-11-01

Measurements of polarized electron-nucleon scattering can be realized at the TESLA linear collider facility with projected luminosities that are about two orders of magnitude higher than those expected of other experiments at comparable energies. Longitudinally polarized electrons, accelerated as a small fraction of the total current in the e + arm of TESLA, can be directed onto a solid state target that may be either longitudinally or transversely polarized. A large variety of polarized parton distribution and fragmentation functions can be determined with unprecedented accuracy, many of them for the first time. A main goal of the experiment is the precise measurement of the x- and Q 2 -dependence of the experimentally totally unknown quark transversity distributions that will complete the information on the nucleon's quark spin structure as relevant for high energy processes. Comparing their Q 2 -evolution to that of the corresponding helicity distributions constitutes an important precision test of the predictive power of QCD in the spin sector. Measuring transversity distributions and tensor charges allows access to the hitherto unmeasured chirally odd operators in QCD which are of great importance to understand the role of chiral symmetry. The possibilities of using unpolarized targets and of experiments with a real photon beam turn TESLA-N into a versatile next-generation facility at the intersection of particle and nuclear physics. (orig.)

A new cavity model for SAS4A

International Nuclear Information System (INIS)

Moxon, D.; Camous, F.

1994-01-01

The SAS4 code is the fourth generation of the SAS series developed at the ANL to study the initiating phase of hypothetical core disruptive accidents in LMFBRs. It was made available to the CEA in order to obtain more validation studies and model developments. The new cavity model described and incorporated in the code was first developed as a stand-alone code. It was thoroughly tested numerically and found to be quick and stable. Tis paper describes only the physical phenomena taken into account

Gadolinium-based magnetic resonance contrast agents at 7 Tesla: in vitro T1 relaxivities in human blood plasma.

Science.gov (United States)

Noebauer-Huhmann, Iris M; Szomolanyi, Pavol; Juras, Vladimír; Kraff, Oliver; Ladd, Mark E; Trattnig, Siegfried

2010-09-01

PURPOSE/INTRODUCTION: The aim of this study was to determine the T1 relaxivities (r1) of 8 gadolinium (Gd)-based MR contrast agents in human blood plasma at 7 Tesla, compared with 3 Tesla. Eight commercially available Gd-based MR contrast agents were diluted in human blood plasma to concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. In vitro measurements were performed at 37 degrees C, on a 7 Tesla and on a 3 Tesla whole-body magnetic resonance imaging scanner. For the determination of T1 relaxation times, Inversion Recovery Sequences with inversion times from 0 to 3500 ms were used. The relaxivities were calculated. The r1 relaxivities of all agents, diluted in human blood plasma at body temperature, were lower at 7 Tesla than at 3 Tesla. The values at 3 Tesla were comparable to those published earlier. Notably, in some agents, a minor negative correlation of r1 with a concentration of up to 2 mmol/L could be observed. This was most pronounced in the agents with the highest protein-binding capacity. At 7 Tesla, the in vitro r1 relaxivities of Gd-based contrast agents in human blood plasma are lower than those at 3 Tesla. This work may serve as a basis for the application of Gd-based MR contrast agents at 7 Tesla. Further studies are required to optimize the contrast agent dose in vivo.

FDTD modeling of EM field inside microwave cavities

CERN Document Server

Narayan, Shiv; Kanth, V Krushna

2017-01-01

This book deals with the EM analysis of closed microwave cavities based on a three-dimensional FDTD method. The EM analysis is carried out for (i) rectangular microwave ovens and (ii) hybrid-cylindrical microwave autoclaves at 2.45 GHz. The field distribution is first estimated inside domestic rectangular ovens in xy-, yz-, and zx-plane. Further, the RF leakage from the oven door is determined to study the effect of leakage radiation on wireless communication at 2.45 GHz. Furthermore, the EM analysis of the autoclave is carried out based on 3D FDTD using staircase approximation. In order to show the capability of autoclaves (excited with five source) for curing the aerospace components and materials, the field distribution inside autoclave cavity is studied in presence of aerospace samples. The FDTD based modelling of oven and autoclave are explained with the appropriate expressions and illustrations.

Prostate cancer detection by prebiopsy 3.0-tesla magnetic resonance imaging

International Nuclear Information System (INIS)

Nishida, Sachiyo; Kinoshita, Hidefumi; Mishima, Takao; Kurokawa, Hiroaki; Sakaida, Noriko; Matsuda, Tadashi

2011-01-01

The diagnostic value of 3.0-Tesla magnetic resonance imaging (MRI) for prostate cancer remains to be determined. The aim of the present study was to assess the features of prostate cancer detectable by prebiopsy 3.0-Tesla MRI. From January 2007 through to December 2008, 116 patients who were examined by prebiopsy 3.0-Tesla MRI underwent radical prostatectomy for localized prostate cancer. Prostate specimens were examined to see whether the largest cancer area was the same as the area indicated on the MRI. Univariate and multivariate logistic regression analyses were conducted to identify variables predictive of agreement between MRI and histopathological findings. Sixty-six (56.9%) patients were suspected of having prostate cancer on the basis of MRI findings. In 49 of these patients (74.2%), it was considered that there was agreement between the abnormal area on the MRI and the index tumor. Univariate analysis revealed that there were significant differences in abnormal digital rectal examination, capsular penetration, the diameter of the index tumor of the radical prostatectomy specimen, and the Gleason scores of the biopsy and radical prostatectomy specimens. Multivariate analysis revealed that the Gleason score of the radical prostatectomy specimen was associated with the accurate detection of the prostate cancer by MRI (P=0.0177). In conclusion, 3.0-Tesla MRI tends to accurately diagnose prostate cancer with high tumor burden and aggressiveness. Multimodal examination (T2-weighted imaging, dynamic contrast-enhanced imaging, and diffusion-weighted imaging) is recommended for the diagnosis of prostate cancer using 3.0-Tesla MRI. (author)

Tests on model of a prestressed concrete nuclear pressure vessel with multiple cavities

International Nuclear Information System (INIS)

Favre, R.; Koprna, M.; Jaccoud, J.P.

1977-01-01

The prestressed concrete pressure vessel (prototype) is a cylinder having a diameter of 48 m and a height of 39 m. It has 25 vertical cavities (reactor, heat exchangers, heat recuperators) and 3 horizontal cavities (gas turbines of 500 kw). The cavities are closed by plugs, and their tightness is ensured by a steel lining. A model, on a scale of 1/20, made of microconcrete, was loaded in several cycles, by a uniform inner pressure in the cavities, increasing to the point of failure. The three successive stages were examined: stage of globally elastic behavior, cracking stage, ultimate stage. The behavior of the model is globally elastic up to an inner pressure of 120 to 130 kp/cm 2 , corresponding to about twice the maximum pressure of service, equal to 65 kp/cm 2 . The prestressed tendons at this stage show practically no stress increase. The first detectable cracks appear on the lateral side half-way up the model, as soon as the pressure exceeded 120 kp/cm 2 . From 150-165 kp/cm 2 , the cracking stage can be considered as achieved and the main crack pattern entirely formed. A horizontal crack continues in the middle of the barrel, as well as vertical cracks at each outer cavity. Beyond a pressure of 150-165 kp/cm 2 the ultimate stage begins. The strains of the stresses in the tendons grow more rapidly. The steel lining is highly solicited. Above about 210 kp/cm 2 the model behaves like a structure composed of a group of concrete blocks bound by the tendons and the lining. The failure (240 kp/cm 2 ) occurred through a mechanism of ejection and bending of the concrete ring at the periphery of the barrel of the vessel, which was solicited mainly in tension

76 FR 60118 - Tesla Motors, Inc. Grant of Petition for Renewal of a Temporary Exemption From the Advanced Air...

Science.gov (United States)

2011-09-28

...-0070] Tesla Motors, Inc. Grant of Petition for Renewal of a Temporary Exemption From the Advanced Air... Protection. SUMMARY: This notice grants the petition of Tesla Motors, Inc. (Tesla) for the renewal of a... the one for Tesla. Over time, the number of petitions for exemption from the advanced air bag...

Theoretical and Experimental Research Performed on the Tesla Turbine - Part I

Directory of Open Access Journals (Sweden)

Dorian Nedelcu

2015-09-01

Full Text Available The paper presents the theoretical and experimental research performed on a Tesla turbine driven by compressed air and designed to equip a teaching laboratory [1], [2]. It introduces the operating principle of the Tesla turbine, which was invented by engineer Nikola Tesla, a turbine which uses discs instead of blades, mounted on a shaft at a small distance between them. The turbine geometry, results from stress and flow calculations performed on the turbine rotor and assembly, using the Simulation modules and SolidWorks Flow Simulation program are presented. After designing the turbine, it becomes the subject of experimental research to determine the curve of the speed depending on the pressure. Also, the experimental research focuses on the behaviour of the turbine from a dynamic point of view [3].

Nikola Tesla: Why was he so much resisted and forgotten? [Retrospectroscope].

Science.gov (United States)

Valentinuzzi, Max E; Ortiz, Martin Hill; Cervantes, Daniel; Leder, Ron S

2016-01-01

Recently, during the Christmas season, a friend of mine visited me and, sneaking a look at my bookshelves, found two rather old Nikola Tesla biographies, which I had used to prepare a "Retrospectroscope" column for the then-named IEEE Engineering in Medicine and Biology Magazine when our dear friend Alvin Wald was its editor-inchief [2]. Eighteen years have elapsed since then; soon, the idea came up of revamping the article. Cynthia Weber, the magazine's current associate editor, considered it acceptable, and here is the new note divided in two parts: that is, a slightly revised version of the original article followed by new material, including some quite interesting information regarding Tesla's homes and laboratories. On top of this, Tesla is not devoid of a science fiction touch, as mentioned at the end.

Hidden Markov Model of atomic quantum jump dynamics in an optically probed cavity

DEFF Research Database (Denmark)

Gammelmark, S.; Molmer, K.; Alt, W.

2014-01-01

We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian...... manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory...

NIKOLA TESLA AND MEDICINE: 160TH ANNIVERSARY OF THE BIRTH OF THE GENIUS WHO GAVE LIGHT TO THE WORLD - PART II.

Science.gov (United States)

Vucevic, Danijela; Dordevic, Drago; Radosavljevic, Tatjana

2016-11-01

Nikola Tesla (1856- 1943) was a genius inventor and scientist, whose contribution to medicine is remarkable. Part I of this article reviewed special contributions of the world renowned scientist to the establishment of radiology as a new discipline in medicine. This paper deals with the use of Tesla currents in medicine. Tesla Currents in Medicine. Tesla's greatest impact on medicine is his invention of a transformer (Tesla coil) for producing high frequency and high voltage currents (Tesla currents). Tesla currents are used in diathermy, as they, while passing through the body, transform electrical energy into a therapeutic heat. In 1891, Tesla passed currents through his own body and was the first to experience their beneficial effects. He kept correspondence on electrotherapy with J. Dugan and S. H. Monell. In 1896, he used high frequency currents and designed an ozone generator for producing ozone, with powerful antiseptic and antibacterial properties. Tesla is famous for his extensive experiments with mechanical vibrations and resonance, examining their effects on the organ ism and pioneering their use for medical purposes. Tesla also designed an oscillator to relieve fatigue of the leg muscles. It is less known that Tesla's inventions (Tesla coil and wireless remote control) are widely used in modern medical equipment. Apart from this, wireless technology is nowadays widely applied in numerous diagnostic and therapeutic procedures. Nikola Tesla was the last Renais- sance figure of the modern era. Tesla bridged three centuries and two millennia by his inventions, and permanently indebted humankind by his epochal discoveries.

Low frequency AC losses in multi filamentary superconductors up to 15 Tesla

International Nuclear Information System (INIS)

Orlando, T.; Braun, C.; Foner, S.; Schwartz, B.; Zieba, A.

1983-01-01

Low frequency (1 Hz) ac losses were measured in a variety of A15 superconducting wires having different fiber geometries. Field modulations ofless than or equal to 1 tesla were superimposed on a fixed background field up to 15 tesla. Losses were measured for Nb 3 Sn in continuous fiber, modified jelly-roll, In Situ, and powder metallurgy processed materials, and for Nb 3 Al powder metallurgy processed materials. The results are compared with dc magnetization measurements. The losses are purely hysteretic at these low frequencies, scale with J /SUB c/ (above about 3 tesla), and are reduced substantially by twisting for all the materials. The lowest losses are observed for the Nb 3 Al wires

Dicke-model simulation via cavity-assisted Raman transitions

Science.gov (United States)

Zhang, Zhiqiang; Lee, Chern Hui; Kumar, Ravi; Arnold, K. J.; Masson, Stuart J.; Grimsmo, A. L.; Parkins, A. S.; Barrett, M. D.

2018-04-01

The Dicke model is of fundamental importance in quantum mechanics for understanding the collective behavior of atoms coupled to a single electromagnetic mode. Here, we demonstrate a Dicke-model simulation via cavity-assisted Raman transitions in a configuration using counterpropagating laser beams. The observations indicate that motional effects should be included to fully account for the results. These results are contrary to experiments using single-beam and copropagating configurations. We give a theoretical description that accounts for the beam geometries used in the experiments and indicates the potential role of motional effects. In particular, a model is given that highlights the influence of Doppler broadening on the observed phase-transition thresholds.

Cryogenic system for the 45 Tesla hybrid magnet

International Nuclear Information System (INIS)

Van Sciver, S.W.; Miller, J.R.; Welton, S.; Schneider-Muntau, H.J.; McIntosh, G.E.

1994-01-01

The 45 Tesla hybrid magnet system will consist of a 14 Tesla superconducting outsert magnet and a 31 Tesla water cooled insert. The magnet is planned for operation in early 1995 at the National High Magnetic Field Laboratory. Its purpose is to provide the highest DC magnetic fields for the materials research community. The present paper discusses the overall design of the cryogenic system for the superconducting magnet. Unique features of this system include static 1.8 K pressurized He II as a coolant for the magnet and a refrigerated structural support system for load transfer during fault conditions. The system will consist of two connected cryostats. The magnet is contained within one cryostat which has a clear warm bore of 616 mm and is designed to be free of system interfaces and therefore minimize interference with the magnet user. A second supply cryostat provides the connections to the refrigeration system and magnet power supply. The magnet and supply cryostats are connected to each other through a horizontal services duct section. Issues to be discussed in the present paper include design and thermal analysis of the magnet system during cooldown and in steady state operation and overall cryogenic system design

SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

International Nuclear Information System (INIS)

Neyman, G

2016-01-01

Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB

SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

Energy Technology Data Exchange (ETDEWEB)

Neyman, G [The Cleveland Clinic Foundation, Cleveland, OH (United States)

2016-06-15

Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB.

A study of nasal cavity volume by magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Tosa, Yasuyoshi [Showa Univ., Tokyo (Japan). School of Medicine

1992-04-01

The nasal cavity volume in 69 healthy volunteers from 8 to 23 years old (17 males and 52 females) was studied using magnetic resonance imaging (MRI). Merits of MRI such as no radiation exposure, less artifact due to bone and air and measurement of intravascular blood flow; and demerits such as contraindication in users of heart pace-makers or magnetic clips, contraindication in people with claustrophobia and influence of environmental magnetic fields must be considered. A Magunetom M10 (Siemens), a superconduction device with 1.0 Tesla magnetic flux density was used. Enhanced patterns of T[sub 1], and pulse lines were photographed at 600 msec TR (repetition time) and 19 msec TE (echo time) using SE (spin echo) and short SE (spin echo), and 3 or 4 mm slices. Photographs were made of the piriform aperture, choana, superior-middle-inferior concha including the nasal meatus, the frontal sinus, maxillary sinus, cribriform plate, and upper surface of the palate. The line connecting the maximum depression point in the nasal root and the pontomedullary junction was selected by sagittal median section, because this corresponds well with the CM (canthomeatal) line which is useful in CT (computed tomography). The transverse section of the nasal cavity volume was traced by display console with an accessory MRI device and calculated by integration of the slice width. The increase of height and body weight neared a plateau at almost 16 years, whereas increase of nasal cavity volume continued until about 20 years. Pearson's coefficient of correlation and regression line were significant. There were no significant differences in these parameters between male and female groups. Comparatively strong correlation between nasal cavity volume, and age, height and body weight was statistically evident. (author).

Climate Modeling: Ocean Cavities below Ice Shelves

Energy Technology Data Exchange (ETDEWEB)

Petersen, Mark Roger [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division

2016-09-12

The Accelerated Climate Model for Energy (ACME), a new initiative by the U.S. Department of Energy, includes unstructured-mesh ocean, land-ice, and sea-ice components using the Model for Prediction Across Scales (MPAS) framework. The ability to run coupled high-resolution global simulations efficiently on large, high-performance computers is a priority for ACME. Sub-ice shelf ocean cavities are a significant new capability in ACME, and will be used to better understand how changing ocean temperature and currents influence glacial melting and retreat. These simulations take advantage of the horizontal variable-resolution mesh and adaptive vertical coordinate in MPAS-Ocean, in order to place high resolution below ice shelves and near grounding lines.

Clinical evaluation of cardiovascular disease by gated-MRI (magnetic resonance imaging) in the operating field of 0.35 and 1.5 Tesla

International Nuclear Information System (INIS)

Nishimura, Tsunehiko; Naito, Hiroaki; Yamada, Yukinori; Kozuka, Takahiro

1985-01-01

To evaluate the clinical usefulness of magnetic resonance imaging (MRI) in the cardiovascular disease, 21 patients were examined using 0.35 and 1.5 Tesla superconductive type (Magnetom, Siemens). In our study, all patients were performed using ECG-gated MRI. Therefore, the cardiac chambers were discriminated clearly from the myocardial wall compared to non-gated MRI. Gated-MRI was performed in 6 normal persons in the operating field at 0.35 and 1.5 Tesla. The image of the latter showed superior than that of the former because of high S/N ratio. In myocardial infarction, infarct area was demonstrated as the wall thinning in 4 of 5 patients. Hypertrophic cardiomyopathy showed thickened left ventricle associated with its narrowed cavity in 7 patients. In the remaining such as congenital and valvular heart disease, global and regional cardiac morphology were assessed noninvasively by gated MRI. In addition, gated MRI was also applied to the diagnosis of peripheral vascular diseases. In dissecting aneurysm, double channels with an intimal flap in the aorta were clearly visualized. And in the aortitis syndrome, aortic dilatation and stenosis were also assessed noninvasively. In conclusion, gated MRI in diagnosing various abnormalities of cardiovascular disease was confirmed. (author)

Beam induced rf cavity transient voltage

International Nuclear Information System (INIS)

Kramer, S.L.; Wang, J.M.

1998-10-01

The authors calculate the transient voltage induced in a radio frequency cavity by the injection of a relativistic bunched beam into a circular accelerator. A simplified model of the beam induced voltage, using a single tone current signal, is generated and compared with the voltage induced by a more realistic model of a point-like bunched beam. The high Q limit of the bunched beam model is shown to be related simply to the simplified model. Both models are shown to induce voltages at the resonant frequency ω r of the cavity and at an integer multiple of the bunch revolution frequency (i.e. the accelerating frequency for powered cavity operation) hω ο . The presence of two nearby frequencies in the cavity leads to a modulation of the carrier wave exp(hω ο t). A special emphasis is placed in this paper on studying the modulation function. These models prove useful for computing the transient voltage induced in superconducting rf cavities, which was the motivation behind this research. The modulation of the transient cavity voltage discussed in this paper is the physical basis of the recently observed and explained new kinds of longitudinal rigid dipole mode which differs from the conventional Robinson mode

Beamstrahlung Photon Load on the TESLA Extraction Septum Blade(LCC-0104)

Energy Technology Data Exchange (ETDEWEB)

Seryi, A

2003-10-02

This note describes work performed in the framework of the International Linear Collider Technical Review Committee [1] to estimate the power load on the TESLA extraction septum blade due to beamstrahlung photons. It is shown, that under realistic conditions the photon load can be several orders of magnitude higher than what was estimated in the TESLA TDR [2] for the ideal Gaussian beams, potentially representing a serious limitation of the current design.

Beamstrahlung Photon Load on the TESLA Extraction Septum Blade(LCC-0104)

International Nuclear Information System (INIS)

Seryi, A

2003-01-01

This note describes work performed in the framework of the International Linear Collider Technical Review Committee [1] to estimate the power load on the TESLA extraction septum blade due to beamstrahlung photons. It is shown, that under realistic conditions the photon load can be several orders of magnitude higher than what was estimated in the TESLA TDR [2] for the ideal Gaussian beams, potentially representing a serious limitation of the current design

Design and performance of a Tesla transformer type relativistic electron beam generator

International Nuclear Information System (INIS)

Jain, K.K.; Chennareddy, D.; John, P.I.; Saxena, Y.C.

1986-01-01

A relativistic electron beam generator driven by an air core Tesla transformer is described. The Tesla transformer circuit analysis is outlined and computational results are presented for the case when the coaxial water line has finite resistance. The transformer has a coupling coefficient of 0.56 and a step-up ratio of 25. The Tesla transformer can provide 800 kV at the peak of the second half cycle of the secondary output voltage and has been tested up to 600 kV. A 100-200 keV, 15-20 kA electron beam having 150 ns pulse width has been obtained. The beam generator described is being used for the beam injection into a toroidal device BETA. (author). 20 refs. 9 figures

Cavity design programs

International Nuclear Information System (INIS)

Nelson, E.M.

1996-01-01

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

TeSLA presentatie voor medewerkers van AMN

NARCIS (Netherlands)

Janssen, José

2017-01-01

Presentatie over Online toetsen voor medewerkers van AMN (www.amn.nl). Topics: assessment onderzoek Welten-instituut en meer in het bijzonder het TeSLA project waarin instrumenten voor authenticatie en auteurschap verificatie worden gecombineerd om betrouwbaar toetsen op afstand mogelijk te maken.

Hippocampal MRI volumetry at 3 Tesla: reliability and practical guidance.

Science.gov (United States)

Jeukens, Cécile R L P N; Vlooswijk, Mariëlle C G; Majoie, H J Marian; de Krom, Marc C T F M; Aldenkamp, Albert P; Hofman, Paul A M; Jansen, Jacobus F A; Backes, Walter H

2009-09-01

Although volumetry of the hippocampus is considered to be an established technique, protocols reported in literature are not described in great detail. This article provides a complete and detailed protocol for hippocampal volumetry applicable to T1-weighted magnetic resonance (MR) images acquired at 3 Tesla, which has become the standard for structural brain research. The protocol encompasses T1-weighted image acquisition at 3 Tesla, anatomic guidelines for manual hippocampus delineation, requirements of delineation software, reliability measures, and criteria to assess and ensure sufficient reliability. Moreover, the validity of the correction for total intracranial volume size was critically assessed. The protocol was applied by 2 readers to the MR images of 36 patients with cryptogenic localization-related epilepsy, 4 patients with unilateral hippocampal sclerosis, and 20 healthy control subjects. The uncorrected hippocampal volumes were 2923 +/- 500 mm3 (mean +/- SD) (left) and 3120 +/- 416 mm3 (right) for the patient group and 3185 +/- 411 mm3 (left) and 3302 +/- 411 mm3 (right) for the healthy control group. The volume of the 4 pathologic hippocampi of the patients with unilateral hippocampal sclerosis was 2980 +/- 422 mm3. The inter-reader reliability values were determined: intraclass-correlation-coefficient (ICC) = 0.87 (left) and 0.86 (right), percentage volume difference (VD) = 7.0 +/- 4.7% (left) and 6.0 +/- 3.8% (right), and overlap ratio (OR) = 0.82 +/- 0.04 (left) and 0.82 +/- 0.03 (right). The positive Pearson correlation between hippocampal volume and total intracranial volume was found to be low: r = 0.48 (P = 0.03, left) and r = 0.62 (P = 0.004, right) and did not significantly reduce the volumetric variances, showing the limited benefit of the brain size correction. A protocol was described to determine hippocampal volumes based on 3 Tesla MR images with high inter-reader reliability. Although the reliability of hippocampal volumetry at 3 Tesla

Nucleonic instruments from VUPJT Tesla

International Nuclear Information System (INIS)

Smola, J.

1986-01-01

The instruments currently produced by Tesla Premysleni are listed and briefly characterized. They include a low level alpha-beta counter, an automatic low level alpha-beta counter, detection units for environmental sample counting, instruments for measuring specific activity of liquids and radon concentration in water, a radioactive aerosol meter, dose ratemeters, portable alpha-beta indicators for surface contamintion monitoring, neutron monitors, single-, two- and three-channel spectrometric units. (M.D.)

Beam position diagnostics with higher order modes in third harmonic superconducting accelerating cavities

International Nuclear Information System (INIS)

Zhang, Pei

2013-02-01

Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrumentation. At the FLASH facility in DESY, 1.3 GHz (known as TESLA) and 3.9 GHz (third harmonic) cavities are installed. Wakefields in 3.9 GHz cavities are significantly larger than in the 1.3 GHz cavities. It is therefore important to mitigate the adverse effects of HOMs to the beam by aligning the beam on the electric axis of the cavities. This alignment requires an accurate beam position diagnostics inside the 3.9 GHz cavities. It is this aspect that is focused on in this thesis. Although the principle of beam diagnostics with HOM has been demonstrated on 1.3 GHz cavities, the realization in 3.9 GHz cavities is considerably more challenging. This is due to the dense HOM spectrum and the relatively strong coupling of most HOMs amongst the four cavities in the third harmonic cryo-module. A comprehensive series of simulations and HOM spectra measurements have been performed in order to study the modal band structure of the 3.9 GHz cavities. The dependencies of

Beam position diagnostics with higher order modes in third harmonic superconducting accelerating cavities

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pei

2013-02-15

Higher order modes (HOM) are electromagnetic resonant fields. They can be excited by an electron beam entering an accelerating cavity, and constitute a component of the wakefield. This wakefield has the potential to dilute the beam quality and, in the worst case, result in a beam-break-up instability. It is therefore important to ensure that these fields are well suppressed by extracting energy through special couplers. In addition, the effect of the transverse wakefield can be reduced by aligning the beam on the cavity axis. This is due to their strength depending on the transverse offset of the excitation beam. For suitably small offsets the dominant components of the transverse wakefield are dipole modes, with a linear dependence on the transverse offset of the excitation bunch. This fact enables the transverse beam position inside the cavity to be determined by measuring the dipole modes extracted from the couplers, similar to a cavity beam position monitor (BPM), but requires no additional vacuum instrumentation. At the FLASH facility in DESY, 1.3 GHz (known as TESLA) and 3.9 GHz (third harmonic) cavities are installed. Wakefields in 3.9 GHz cavities are significantly larger than in the 1.3 GHz cavities. It is therefore important to mitigate the adverse effects of HOMs to the beam by aligning the beam on the electric axis of the cavities. This alignment requires an accurate beam position diagnostics inside the 3.9 GHz cavities. It is this aspect that is focused on in this thesis. Although the principle of beam diagnostics with HOM has been demonstrated on 1.3 GHz cavities, the realization in 3.9 GHz cavities is considerably more challenging. This is due to the dense HOM spectrum and the relatively strong coupling of most HOMs amongst the four cavities in the third harmonic cryo-module. A comprehensive series of simulations and HOM spectra measurements have been performed in order to study the modal band structure of the 3.9 GHz cavities. The dependencies of

The 4-parameter Compressible Packing Model (CPM) including a critical cavity size ratio

Science.gov (United States)

Roquier, Gerard

2017-06-01

The 4-parameter Compressible Packing Model (CPM) has been developed to predict the packing density of mixtures constituted by bidisperse spherical particles. The four parameters are: the wall effect and the loosening effect coefficients, the compaction index and a critical cavity size ratio. The two geometrical interactions have been studied theoretically on the basis of a spherical cell centered on a secondary class bead. For the loosening effect, a critical cavity size ratio, below which a fine particle can be inserted into a small cavity created by touching coarser particles, is introduced. This is the only parameter which requires adaptation to extend the model to other types of particles. The 4-parameter CPM demonstrates its efficiency on frictionless glass beads (300 values), spherical particles numerically simulated (20 values), round natural particles (125 values) and crushed particles (335 values) with correlation coefficients equal to respectively 99.0%, 98.7%, 97.8%, 96.4% and mean deviations equal to respectively 0.007, 0.006, 0.007, 0.010.

Displacement-noise-free gravitational-wave detection with a single Fabry-Perot cavity: A toy model

International Nuclear Information System (INIS)

Tarabrin, Sergey P.; Vyatchanin, Sergey P.

2008-01-01

We propose a detuned Fabry-Perot cavity, pumped through both the mirrors, as a toy model of the gravitational-wave (GW) detector partially free from displacement noise of the test masses. It is demonstrated that the noise of cavity mirrors can be eliminated, but the one of lasers and detectors cannot. The isolation of the GW signal from displacement noise of the mirrors is achieved in a proper linear combination of the cavity output signals. The construction of such a linear combination is possible due to the difference between the reflected and transmitted output signals of detuned cavity. We demonstrate that in low-frequency region the obtained displacement-noise-free response signal is much stronger than the f gw 3 -limited sensitivity of displacement-noise-free interferometers recently proposed by S. Kawamura and Y. Chen. However, the loss of the resonant gain in the noise cancelation procedure results is the sensitivity limitation of our toy model by displacement noise of lasers and detectors

Evaluation of new injection and cavity preparation model in local anesthesia teaching

NARCIS (Netherlands)

Yekta, S.S.; Lampert, F.; Kazemi, S.; Kazemi, R.; Brand, H.S.; Baart, J.A.; Mazandarani, M.

2013-01-01

The aim of this study was to evaluate a recently developed preclinical injection and cavity preparation model in local anesthesia. Thirty-three dental students administered an inferior alveolar nerve block injection in the model, followed by preparation on a tooth. The injection was evaluated by

Dynamics of interacting Dicke model in a coupled-cavity array

Science.gov (United States)

Badshah, Fazal; Qamar, Shahid; Paternostro, Mauro

2014-09-01

We consider the dynamics of an array of mutually interacting cavities, each containing an ensemble of N two-level atoms. By exploring the possibilities offered by ensembles of various dimensions and a range of atom-light and photon-hopping values, we investigate the generation of multisite entanglement, as well as the performance of excitation transfer across the array, resulting from the competition between on-site nonlinearities of the matter-light interaction and intersite photon hopping. In particular, for a three-cavity interacting system it is observed that the initial excitation in the first cavity completely transfers to the ensemble in the third cavity through the hopping of photons between the adjacent cavities. Probabilities of the transfer of excitation of the cavity modes and ensembles exhibit characteristics of fast and slow oscillations governed by coupling and hopping parameters, respectively. In the large-hopping case, by seeding an initial excitation in the cavity at the center of the array, a tripartite W state, as well as a bipartite maximally entangled state, is obtained, depending on the interaction time. Population of the ensemble in a cavity has a positive impact on the rate of excitation transfer between the ensembles and their local cavity modes. In particular, for ensembles of five to seven atoms, tripartite W states can be produced even when the hopping rate is comparable to the cavity-atom coupling rate. A similar behavior of the transfer of excitation is observed for a four-coupled-cavity system with two initial excitations.

Magnetic resonance examinations at two Tesla

International Nuclear Information System (INIS)

Grabbe, E.; Maas, R.; Heller, M.; Denkhaus, H.; Buecheler, E.

1986-01-01

After having used a 2 Tesla prototype whole body scanner for about one and a half years, it is now possible to comment on the clinical value of high field strengths. The methods and techniques employed are described. The problems arising from high field strengths are discussed and their effect on clinical diagnosis is indicated. (orig.) [de

Note: Tesla based pulse generator for electrical breakdown study of liquid dielectrics

Science.gov (United States)

Veda Prakash, G.; Kumar, R.; Patel, J.; Saurabh, K.; Shyam, A.

2013-12-01

In the process of studying charge holding capability and delay time for breakdown in liquids under nanosecond (ns) time scales, a Tesla based pulse generator has been developed. Pulse generator is a combination of Tesla transformer, pulse forming line, a fast closing switch, and test chamber. Use of Tesla transformer over conventional Marx generators makes the pulse generator very compact, cost effective, and requires less maintenance. The system has been designed and developed to deliver maximum output voltage of 300 kV and rise time of the order of tens of nanoseconds. The paper deals with the system design parameters, breakdown test procedure, and various experimental results. To validate the pulse generator performance, experimental results have been compared with PSPICE simulation software and are in good agreement with simulation results.

Cortical microinfarcts detected in vivo on 3 Tesla MRI: clinical and radiological correlates.

Science.gov (United States)

van Dalen, Jan Willem; Scuric, Eva E M; van Veluw, Susanne J; Caan, Matthan W A; Nederveen, Aart J; Biessels, Geert Jan; van Gool, Willem A; Richard, Edo

2015-01-01

Cortical microinfarcts (CMIs) are a common postmortem finding associated with vascular risk factors, cognitive decline, and dementia. Recently, CMIs identified in vivo on 7 Tesla MRI also proved retraceable on 3 Tesla MRI. We evaluated CMIs on 3 Tesla MRI in a population-based cohort of 194 nondemented older people (72-80 years) with systolic hypertension. Using a case-control design, participants with and without CMIs were compared on age, sex, cardiovascular risk factors, and white matter hyperintensity volume. We identified 23 CMIs in 12 participants (6%). CMIs were associated with older age, higher diastolic blood pressure, and a history of recent stroke. There was a trend for a higher white matter hyperintensity volume in participants with CMIs. We found an association of CMIs with clinical parameters, including age and cardiovascular risk factors. Although the prevalence of CMIs is relatively low, our results suggest that the study of CMIs in larger clinical studies is possible using 3 Tesla MRI. This opens the possibility of large-scale prospective investigation of the clinical relevance of CMIs in older people. © 2014 American Heart Association, Inc.

Prospects for 6 to 10 tesla magnets for a TEVATRON upgrade

International Nuclear Information System (INIS)

Mantsch, Paul M.

1988-01-01

The first SSC physics is at least 10 years away. An upgrade of the Fermilab Tevatron will ensure the continuity of a vigorous high-energy physics program until the SSC turns on. Three basic proposals are under consideration: /bar p/p at 3 /times/ 10 31 --Increase luminosity by improvements to the p source. pp at 1 TeV and 2 /times/ 10 32 --Move the main ring to a new tunnel, build a second Tevatron ring, and /bar p/p > 1.5 TeV and 7 /times/ 10 30 --Replace the tevatron with a higher energy ring. The last two options requires about a hundred 6.6-tesla dipoles in addition to a ring of Tevatron strength (4.4 T) magnets. These higher-field magnets are necessary in both rings to lengthen the straight sections in order to realize the collision optics. The third option requires a ring of magnets of 6.6 T or slightly higher to replace the present Tevatron plus a number of special 8--9 tesla magnets. The viability of the high-energy option then depends on the practicality of sizable numbers of reliable 8--9 tesla dipoles as well as 800 6.6-tesla dipoles. The following develops a specification for an 8.8 T dipole, examines the design considerations and reviews the current state of high-field magnet development. 22 figs., 3 tabs

Conceptual design of a 20 Tesla pulsed solenoid for a laser solenoid fusion reactor

International Nuclear Information System (INIS)

Nolan, J.J.; Averill, R.J.

1977-01-01

Design considerations are described for a strip wound solenoid which is pulsed to 20 tesla while immersed in a 20 tesla bias field so as to achieve within the bore of the pulsed solenoid at net field sequence starting at 20 tesla and going first down to zero, then up to 40 tesla, and finally back to 20 tesla in a period of about 5 x 10 -3 seconds. The important parameters of the solenoid, e.g., aperture, build, turns, stored and dissipated energy, field intensity and powering circuit, are given. A numerical example for a specific design is presented. Mechanical stresses in the solenoid and the subsequent choice of materials for coil construction are discussed. Although several possible design difficulties are not discussed in this preliminary report of a conceptual magnet design, such as uniformity of field, long-term stability of insulation under neutron bombardment and choice of structural materials of appropriate tensile strength and elasticity to withstand magnetic forces developed, these questions are addressed in detail in the complete design report and in part in reference one. Furthermore, the authors feel that the problems encountered in this conceptual design are surmountable and are not a hindrance to the construction of such a magnet system

NIKOLA TESLA AND MEDICINE: 160TH ANNIVERSARY OF THE BIRTH OF THE GENIUS WHO GAVE LIGHT TO THE WORLD - PART I.

Science.gov (United States)

Vucevic, Danijela; Dordevic, Drago; Radosavljevic, Tatjana

2016-09-01

The interest in Nikola Tesla, a scientist, physicist, engineer and inventor, is constantly growing. In the millennialong history of human civilization, it is almost impossible to find another person whose life and work has been under so much scrutiny of such a wide range of researchers, medical professionals included. Although Tesla was not primarily dedicated to biomedical research, his work significantly contributed to the development of radiology, and high frequency electrotherapy. This paper deals with the impact of Tesla's work on the development of a new medical branch - radiology. Nikola Tesla and the Discovery of X-ray radiation. Tesla pioneered the use of X-rays for medical purposes, practically laying the foundations of radiology. Namely, since 1887, Tesla periodically experimented with X-rays, at that time still unknown and unnamed, which he called "shadowgraphs". Moreover, at the end of 1894, lie conducted extensive research focusing on X-rays, but unfortunately it was inlerrupted after the fire burning down his laboratory in 1895. In 1896 and 1897, Tesla published ten papers on the biologic effects of X-ray radiation. All his studies on X-rays were experimental. During 1896 and 1897, Tesla continued improving X-ray devices. Apart from this, Tesla was the first to point out the harmful effects of exposure to X-ray radiation on human body. Nikola Tesla was a visionary genius of the future. Tesla's pioneer steps, made more than a century ago in the domain of radiology, are still being used today.

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.

Diagnosis of rotator cuff tears using 3-Tesla MRI versus 3-Tesla MRA: a systematic review and meta-analysis.

Science.gov (United States)

McGarvey, Ciaran; Harb, Ziad; Smith, Christian; Houghton, Russell; Corbett, Steven; Ajuied, Adil

2016-02-01

To compare the diagnostic accuracy of magnetic resonance imaging (MRI), 2-dimensional magnetic resonance arthrogram (MRA) and 3-dimensional isotropic MRA in the diagnosis of rotator cuff tears when performed exclusively at 3-T. A systematic review was undertaken of the Cochrane, MEDLINE and PubMed databases in accordance with the PRISMA guidelines. Studies comparing 3-T MRI or 3-T MRA (index tests) to arthroscopic surgical findings (reference test) were included. Methodological appraisal was performed using QUADAS 2. Pooled sensitivity and specificity were calculated and summary receiver-operating curves generated. Kappa coefficients quantified inter-observer reliability. Fourteen studies comprising 1332 patients were identified for inclusion. Twelve studies were retrospective and there were concerns regarding index test bias and applicability in nine and six studies respectively. Reference test bias was a concern in all studies. Both 3-T MRI and 3-T MRA showed similar excellent diagnostic accuracy for full-thickness supraspinatus tears. Concerning partial-thickness supraspinatus tears, 3-T 2D MRA was significantly more sensitive (86.6 vs. 80.5 %, p = 0.014) but significantly less specific (95.2 vs. 100 %, p Tesla 3D isotropic MRA showed similar accuracy to 3-T conventional 2D MRA. Three-Tesla MRI appeared equivalent to 3-T MRA in the diagnosis of full- and partial-thickness tears, although there was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA appears equivalent to 3-T 2D MRA for all types of tears.

Numerical model for the solution of two-dimensional natural convection problems in arbitrary cavities

International Nuclear Information System (INIS)

Milioli, F.E.

1985-01-01

In this research work a numerical model for the solution of two-dimensional natural convection problems in arbitrary cavities of a Boussinesq fluid is presented. The conservation equations are written in a general curvilinear coordinate system which matches the irregular boundaries of the domain. The nonorthogonal system is generated by a suitable system of elliptic equations. The momentum and continuity equations are transformed from the Cartesian system to the general curvilinear system keeping the Cartesian velocity components as the dependent variables in the transformed domain. Finite difference equations are obtained for the contravariant velocity components in the transformed domain. The numerical calculations are performed in a fixed rectangular domain and both the Cartesian and the contravariant velocity components take part in the solutiomn procedure. The dependent variables are arranged on the grid in a staggered manner. The numerical model is tested by solving the driven flow in a square cavity with a moving side using a nonorthogoanl grid. The natural convenction in a square cavity, using an orthogonal and a nonorthogonal grid, is also solved for the model test. Also, the solution for the buoyancy flow between a square cylinder placed inside a circular cylinder is presented. The results of the test problems are compared with those available in the specialized literature. Finally, in order to show the generality of the model, the natural convection problem inside a very irregular cavity is presented. (Author) [pt

Plasmonic-cavity model for radiating nano-rod antennas

DEFF Research Database (Denmark)

Peng, Liang; Mortensen, N. Asger

2014-01-01

In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition and the ......In this paper, we propose the analytical solution of nano-rod antennas utilizing a cylindrical harmonics expansion. By treating the metallic nano-rods as plasmonic cavities, we derive closed-form expressions for both the internal and the radiated fields, as well as the resonant condition...... and the radiation efficiency. With our theoretical model, we show that besides the plasmonic resonances, efficient radiation takes advantage of (a) rendering a large value of the rods' radius and (b) a central-fed profile, through which the radiation efficiency can reach up to 70% and even higher in a wide...... frequency band. Our theoretical expressions and conclusions are general and pave the way for engineering and further optimization of optical antenna systems and their radiation patterns....

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

International Nuclear Information System (INIS)

Jana, Arup Ratan; Kumar, V.

2011-01-01

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

Nikola Tesla and medicine: 160th anniversary of the birth of the genius who gave light to the world - Part II

OpenAIRE

Vučević, Danijela; Đorđević, Drago; Radosavljević, Tatjana

2016-01-01

Introduction. Nikola Tesla (1856 - 1943) was a genius inventor and scientist, whose contribution to medicine is remarkable. Part I of this article reviewed special contributions of the world renowned scientist to the establishment of radiology as a new discipline in medicine. This paper deals with the use of Tesla currents in medicine. Tesla Currents in Medicine. Tesla's greatest impact on medicine is his invention of a transformer (Tesla coil) for producing high frequency and high voltage cu...

A New Signal Model for Axion Cavity Searches from N -body Simulations

Energy Technology Data Exchange (ETDEWEB)

Lentz, Erik W.; Rosenberg, Leslie J. [Physics Department, University of Washington, Seattle, WA 98195-1580 (United States); Quinn, Thomas R.; Tremmel, Michael J., E-mail: lentze@phys.washington.edu, E-mail: ljrosenberg@phys.washington.edu, E-mail: trq@astro.washington.edu, E-mail: mjt29@astro.washington.edu [Astronomy Department, University of Washington, Seattle, WA 98195-1580 (United States)

2017-08-20

Signal estimates for direct axion dark matter (DM) searches have used the isothermal sphere halo model for the last several decades. While insightful, the isothermal model does not capture effects from a halo’s infall history nor the influence of baryonic matter, which has been shown to significantly influence a halo’s inner structure. The high resolution of cavity axion detectors can make use of modern cosmological structure-formation simulations, which begin from realistic initial conditions, incorporate a wide range of baryonic physics, and are capable of resolving detailed structure. This work uses a state-of-the-art cosmological N -body+Smoothed-Particle Hydrodynamics simulation to develop an improved signal model for axion cavity searches. Signal shapes from a class of galaxies encompassing the Milky Way are found to depart significantly from the isothermal sphere. A new signal model for axion detectors is proposed and projected sensitivity bounds on the Axion DM eXperiment (ADMX) data are presented.

Computer simulation and cold model testing of CCL cavities

International Nuclear Information System (INIS)

Chang, C.R.; Yao, C.G.; Swenson, D.A.; Funk, L.W.

1993-01-01

The SSC coupled-cavity-linac (CCL) consists of nine modules with eight tanks in each module. Multicavity magnetically coupled bridge couplers are used to couple the eight tanks within a module into one RF resonant chain. The operating frequency is 1282.851 MHz. In this paper the authors discuss both computer calculations and cold model measurements to determine the geometry dimension of the RF structure

Novel techniques for 7 tesla breast MRI

NARCIS (Netherlands)

van der Velden, T.A.

2017-01-01

This thesis introduced several new techniques to the field of 7 tesla breast MRI, enabling high field multi-parametric MR imaging and, potentially, patient specific treatment planning. Chapter 2 described the development of a RF coil setup for bilateral breast MR imaging and 31P spectroscopy. This

Speed Geometric Quantum Logical Gate Based on Double-Hamiltonian Evolution under Large-Detuning Cavity QED Model

International Nuclear Information System (INIS)

Chen Changyong; Liu Zongliang; Kang Shuai; Li Shaohua

2010-01-01

We introduce the double-Hamiltonian evolution technique approach to investigate the unconventional geometric quantum logical gate with dissipation under the model of many identical three-level atoms in a cavity, driven by a classical field. Our concrete calculation is made for the case of two atoms for the large-detuning interaction of the atoms with the cavity mode. The main advantage of our scheme is of eliminating the photon flutuation in the cavity mode during the gating. The corresponding analytical results will be helpful for experimental realization of speed geometric quantum logical gate in real cavities. (general)

MODERN ELECTRIC CARS OF TESLA MOTORS COMPANY

Directory of Open Access Journals (Sweden)

O. F. Vynakov

2016-08-01

Full Text Available This overview article shows the advantages of a modern electric car as compared with internal combustion cars by the example of the electric vehicles of Tesla Motors Company. It (в смысле- статья describes the history of this firm, provides technical and tactical characteristics of three modifications of electric vehicles produced by Tesla Motors. Modern electric cars are not less powerful than cars with combustion engines both in speed and acceleration amount. They are reliable, economical and safe in operation. With every year the maximum range of an electric car is increasing and its battery charging time is decreasing.Solving the problem of environmental safety, the governments of most countries are trying to encourage people to switch to electric cars by creating subsidy programs, lending and abolition of taxation. Therefore, the advent of an electric vehicle in all major cities of the world is inevitable.

Diagnostic usefulness of 3 tesla MRI of the brain for cushing disease in a child.

Science.gov (United States)

Ono, Erina; Ozawa, Ayako; Matoba, Kaori; Motoki, Takanori; Tajima, Asako; Miyata, Ichiro; Ito, Junko; Inoshita, Naoko; Yamada, Syozo; Ida, Hiroyuki

2011-10-01

It is sometimes difficult to confirm the location of a microadenoma in Cushing disease. Recently, we experienced an 11-yr-old female case of Cushing disease with hyperprolactinemia. She was referred to our hospital because of decrease of height velocity with body weight gain. On admission, she had typical symptoms of Cushing syndrome. Although no pituitary microadenomas were detected on 1.5 Tesla MRI of the brain, endocrinological examinations including IPS and CS sampling were consistent with Cushing disease with hyperprolactinemia. Oral administration of methyrapone instead of neurosurgery was started after discharge, but subsequent 3 Tesla MRI of the brain clearly demonstrated a 3-mm less-enhanced lesion in the left side of the pituitary gland. Finally, transsphenoidal surgery was performed, and a 3.5-mm left-sided microadenoma was resected. Compared with 1.5 Tesla MRI, 3 Tesla MRI offers the advantage of a higher signal to noise ratio (SNR), which provides higher resolution and proper image quality. Therefore, 3 Tesla MRI is a very useful tool to localize microadenomas in Cushing disease in children as well as in adults. It will be the first choice of radiological examinations in suspected cases of Cushing disease.

76 FR 33402 - Tesla Motors, Inc.; Receipt of Petition for Renewal of Temporary Exemption from the Advanced Air...

Science.gov (United States)

2011-06-08

...-0070] Tesla Motors, Inc.; Receipt of Petition for Renewal of Temporary Exemption from the Advanced Air... Protection. SUMMARY: In accordance with the procedures in 49 CFR Part 555, Tesla Motors, Inc., has petitioned... Petition In accordance with 49 U.S.C. 30113 and the procedures in 49 CFR Part 555, Tesla Motors, Inc...

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

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

Modeling of Reduced-Beta Half-Reentrant Cavities: Final Report

International Nuclear Information System (INIS)

Popielarksi, J.T.; Hartung, W.; Johnson, M.J.

2011-01-01

The linear accelerator for the Spallation Neutron Source uses multi-cell elliptical superconducting cavities to provide much of the accelerating voltage. Similar technology is being considered for other projects, including a proposed superconducting proton linac at Fermilab and the European Spallation Source. A new type of accelerating structure, a 'half-reentrant' elliptical cavity has been studied at Michigan State University. A half-reentrant cavity can potentially improve upon existing elliptical cavity designs by reducing the cryogenic load by as much as 40% for the same accelerating gradient. Alternatively, with the same peak surface magnetic field as traditional elliptical cavities, it is anticipated that half-reentrant designs could operate at up to 25% higher accelerating gradient. With a half-reentrant shape, liquids can drain easily during chemical etching and high pressure rinsing, which allows standard multi-cell processing techniques to be used. Electromagnetic designs have been developed for three half-reentrant cell shapes suitable for an ion or proton linac (β = 0.47, 0.61 and 0.81). The mechanical designs have been done for prototypes at 805 MHz. The design and optimization of the reduced-β half-reentrant cavities are summarized in this report.

Non-homogeneous model for a side heated square cavity filled with a nanofluid

International Nuclear Information System (INIS)

Celli, Michele

2013-01-01

Highlights: • A side heated two dimensional square cavity filled with a nanofluid is studied. • A non-homogeneous model is taken into account. • The properties of the nanofluid are functions of the fraction of nanoparticles. • Low-Rayleigh numbers yield a non-homogeneous distribution of the nanoparticles. -- Abstract: A side heated two dimensional square cavity filled with a nanofluid is here studied. The side heating condition is obtained by imposing two different uniform temperatures at the vertical boundary walls. The horizontal walls are assumed to be adiabatic and all boundaries are assumed to be impermeable to the base fluid and to the nanoparticles. In order to study the behavior of the nanofluid, a non-homogeneous model is taken into account. The thermophysical properties of the nanofluid are assumed to be functions of the average volume fraction of nanoparticles dispersed inside the cavity. The definitions of the nondimensional governing parameters (Rayleigh number, Prandtl number and Lewis number) are exactly the same as for the clear fluids. The distribution of the nanoparticles shows a particular sensitivity to the low Rayleigh numbers. The average Nusselt number at the vertical walls is sensitive to the average volume fraction of the nanoparticles dispersed inside the cavity and it is also sensitive to the definition of the thermophysical properties of the nanofluid. Highly viscous base fluids lead to a critical behavior of the model when the simulation is performed in pure conduction regime. The solution of the problem is obtained numerically by means of a Galerkin finite element method

Automated 3D Damaged Cavity Model Builder for Lower Surface Acreage Tile on Orbiter

Science.gov (United States)

Belknap, Shannon; Zhang, Michael

2013-01-01

The 3D Automated Thermal Tool for Damaged Acreage Tile Math Model builder was developed to perform quickly and accurately 3D thermal analyses on damaged lower surface acreage tiles and structures beneath the damaged locations on a Space Shuttle Orbiter. The 3D model builder created both TRASYS geometric math models (GMMs) and SINDA thermal math models (TMMs) to simulate an idealized damaged cavity in the damaged tile(s). The GMMs are processed in TRASYS to generate radiation conductors between the surfaces in the cavity. The radiation conductors are inserted into the TMMs, which are processed in SINDA to generate temperature histories for all of the nodes on each layer of the TMM. The invention allows a thermal analyst to create quickly and accurately a 3D model of a damaged lower surface tile on the orbiter. The 3D model builder can generate a GMM and the correspond ing TMM in one or two minutes, with the damaged cavity included in the tile material. A separate program creates a configuration file, which would take a couple of minutes to edit. This configuration file is read by the model builder program to determine the location of the damage, the correct tile type, tile thickness, structure thickness, and SIP thickness of the damage, so that the model builder program can build an accurate model at the specified location. Once the models are built, they are processed by the TRASYS and SINDA.

Three-dimensional FDTD Modeling of Earth-ionosphere Cavity Resonances

Science.gov (United States)

Yang, H.; Pasko, V. P.

2003-12-01

Resonance properties of the earth-ionosphere cavity were first predicted by W. O. Schumann in 1952 [Schumann, Z. Naturforsch. A, 7, 149, 1952]. Since then observations of extremely low frequency (ELF) signals in the frequency range 1-500 Hz have become a powerful tool for monitoring of global lightning activity and planetary scale variability of the lower ionosphere, as well as, in recent years, for location and remote sensing of sprites, jets and elves and associated lightning discharges [e.g., Sato et al., JASTP, 65, 607, 2003; Su et al., Nature, 423, 974, 2003; and references cited therein]. The simplicity and flexibility of finite difference time domain (FDTD) technique for finding first principles solutions of electromagnetic problems in a medium with arbitrary inhomogeneities and ever-increasing computer power make FDTD an excellent candidate to be the technique of the future in development of realistic numerical models of VLF/ELF propagation in Earth-ionosphere waveguide [Cummer, IEEE Trans. Antennas Propagat., 48, 1420, 2000], and several reports about successful application of the FDTD technique for solution of related problems have recently appeared in the literature [e.g., Thevenot et al., Ann. Telecommun., 54, 297, 1999; Cummer, 2000; Berenger, Ann. Telecommun., 57, 1059, 2002, Simpson and Taflove, IEEE Antennas Wireless Propagat. Lett., 1, 53, 2002]. In this talk we will present results from a new three-dimensional spherical FDTD model, which is designed for studies of ELF electromagnetic signals under 100 Hz in the earth-ionosphere cavity. The model accounts for a realistic latitudinal and longitudinal variation of ground conductivity (i.e., for the boundaries between oceans and continents) by employing a broadband surface impedance technique proposed in [Breggs et al., IEEE Trans. Antenna Propagat., 41, 118, 1993]. The realistic distributions of atmospheric/lower ionospheric conductivity are derived from the international reference ionosphere model

Beam dynamic issues in TESLA damping ring

International Nuclear Information System (INIS)

Shiltsev, V.

1996-05-01

In this paper we study general requirements on impedances of the linear collider TESLA damping ring design. Quantitative consideration is performed for 17-km long ''dog-bone'' ring. Beam dynamics in alternative options of 6.3 and 2.3-km long damping rings is briefly discussed. 5 refs., 2 tabs

Diagnosis of rotator cuff tears using 3-Tesla MRI versus 3-Tesla MRA: a systematic review and meta-analysis

Energy Technology Data Exchange (ETDEWEB)

McGarvey, Ciaran; Harb, Ziad; Smith, Christian; Ajuied, Adil [Guy' s and St Thomas' Hospital, King' s Health Partners, Department of Trauma and Orthopaedics, London (United Kingdom); Houghton, Russell [Guy' s and St Thomas' Hospital, King' s Health Partners, Department of Radiology, London (United Kingdom); Corbett, Steven [Guy' s and St Thomas' Hospital, King' s Health Partners, Department of Trauma and Orthopaedics, London (United Kingdom); Fortius Clinic, London (United Kingdom)

2016-02-15

To compare the diagnostic accuracy of magnetic resonance imaging (MRI), 2-dimensional magnetic resonance arthrogram (MRA) and 3-dimensional isotropic MRA in the diagnosis of rotator cuff tears when performed exclusively at 3-T. A systematic review was undertaken of the Cochrane, MEDLINE and PubMed databases in accordance with the PRISMA guidelines. Studies comparing 3-T MRI or 3-T MRA (index tests) to arthroscopic surgical findings (reference test) were included. Methodological appraisal was performed using QUADAS 2. Pooled sensitivity and specificity were calculated and summary receiver-operating curves generated. Kappa coefficients quantified inter-observer reliability. Fourteen studies comprising 1332 patients were identified for inclusion. Twelve studies were retrospective and there were concerns regarding index test bias and applicability in nine and six studies respectively. Reference test bias was a concern in all studies. Both 3-T MRI and 3-T MRA showed similar excellent diagnostic accuracy for full-thickness supraspinatus tears. Concerning partial-thickness supraspinatus tears, 3-T 2D MRA was significantly more sensitive (86.6 vs. 80.5 %, p = 0.014) but significantly less specific (95.2 vs. 100 %, p < 0.001). There was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA showed similar accuracy to 3-T conventional 2D MRA. Three-Tesla MRI appeared equivalent to 3-T MRA in the diagnosis of full- and partial-thickness tears, although there was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA appears equivalent to 3-T 2D MRA for all types of tears. (orig.)

Diagnosis of rotator cuff tears using 3-Tesla MRI versus 3-Tesla MRA: a systematic review and meta-analysis

International Nuclear Information System (INIS)

McGarvey, Ciaran; Harb, Ziad; Smith, Christian; Ajuied, Adil; Houghton, Russell; Corbett, Steven

2016-01-01

To compare the diagnostic accuracy of magnetic resonance imaging (MRI), 2-dimensional magnetic resonance arthrogram (MRA) and 3-dimensional isotropic MRA in the diagnosis of rotator cuff tears when performed exclusively at 3-T. A systematic review was undertaken of the Cochrane, MEDLINE and PubMed databases in accordance with the PRISMA guidelines. Studies comparing 3-T MRI or 3-T MRA (index tests) to arthroscopic surgical findings (reference test) were included. Methodological appraisal was performed using QUADAS 2. Pooled sensitivity and specificity were calculated and summary receiver-operating curves generated. Kappa coefficients quantified inter-observer reliability. Fourteen studies comprising 1332 patients were identified for inclusion. Twelve studies were retrospective and there were concerns regarding index test bias and applicability in nine and six studies respectively. Reference test bias was a concern in all studies. Both 3-T MRI and 3-T MRA showed similar excellent diagnostic accuracy for full-thickness supraspinatus tears. Concerning partial-thickness supraspinatus tears, 3-T 2D MRA was significantly more sensitive (86.6 vs. 80.5 %, p = 0.014) but significantly less specific (95.2 vs. 100 %, p < 0.001). There was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA showed similar accuracy to 3-T conventional 2D MRA. Three-Tesla MRI appeared equivalent to 3-T MRA in the diagnosis of full- and partial-thickness tears, although there was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA appears equivalent to 3-T 2D MRA for all types of tears. (orig.)

Thermal conditions within tree cavities in ponderosa pine (Pinus ponderosa) forests: potential implications for cavity users

Science.gov (United States)

Vierling, Kerri T.; Lorenz, Teresa J.; Cunningham, Patrick; Potterf, Kelsi

2017-11-01

Tree cavities provide critical roosting and breeding sites for multiple species, and thermal environments in these cavities are important to understand. Our objectives were to (1) describe thermal characteristics in cavities between June 3 and August 9, 2014, and (2) investigate the environmental factors that influence cavity temperatures. We placed iButtons in 84 different cavities in ponderosa pine (Pinus ponderosa) forests in central Washington, and took hourly measurements for at least 8 days in each cavity. Temperatures above 40 °C are generally lethal to developing avian embryos, and 18% of the cavities had internal temperatures of ≥ 40 °C for at least 1 h of each day. We modeled daily maximum cavity temperature, the amplitude of daily cavity temperatures, and the difference between the mean internal cavity and mean ambient temperatures as a function of several environmental variables. These variables included canopy cover, tree diameter at cavity height, cavity volume, entrance area, the hardness of the cavity body, the hardness of the cavity sill (which is the wood below the cavity entrance which forms the barrier between the cavity and the external environment), and sill width. Ambient temperature had the largest effect size for maximum cavity temperature and amplitude. Larger trees with harder sills may provide more thermally stable cavity environments, and decayed sills were positively associated with maximum cavity temperatures. Summer temperatures are projected to increase in this region, and additional research is needed to determine how the thermal environments of cavities will influence species occupancy, breeding, and survival.

Diffusion-weighted whole-body MR imaging with background body signal suppression: a feasibility study at 3.0 Tesla

International Nuclear Information System (INIS)

Muertz, Petra; Krautmacher, Carsten; Traeber, Frank; Schild, Hans H.; Willinek, Winfried A.; Gieseke, Juergen

2007-01-01

The purpose was to provide a diffusion-weighted whole-body magnetic resonance (MR) imaging sequence with background body signal suppression (DWIBS) at 3.0 Tesla. A diffusion-weighted spin-echo echo-planar imaging sequence was combined with the following methods of fat suppression: short TI inversion recovery (STIR), spectral attenuated inversion recovery (SPAIR), and spectral presaturation by inversion recovery (SPIR). Optimized sequences were implemented on a 3.0- and a 1.5-Tesla system and evaluated in three healthy volunteers and six patients with various lesions in the neck, chest, and abdomen on the basis of reconstructed maximum intensity projection images. In one patient with metastases of malignant melanoma, DWIBS was compared with 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET). Good fat suppression for all regions and diagnostic image quality in all cases could be obtained at 3.0 Tesla with the STIR method. In comparison with 1.5 Tesla, DWIBS images at 3.0 Tesla were judged to provide a better lesion-to-bone tissue contrast. However, larger susceptibility-induced image distortions and signal intensity losses, stronger blurring artifacts, and more pronounced motion artifacts degraded the image quality at 3.0 Tesla. A good correlation was found between the metastases as depicted by DWIBS and those as visualized by FDG-PET. DWIBS is feasible at 3.0 Tesla with diagnostic image quality. (orig.)

Three-Dimensional Morphology of a Coronal Prominence Cavity

Science.gov (United States)

Gibson, S. E.; Kucera, T. A.; Rastawicki, D.; Dove, J.; deToma, G.; Hao, J.; Hill, S.; Hudson, H. S.; Marque, C.; McIntosh, P. S.;

Breath-hold imaging of the coronary arteries using Quiescent-Interval Slice-Selective (QISS) magnetic resonance angiography: pilot study at 1.5 Tesla and 3 Tesla.

Science.gov (United States)

Edelman, Robert R; Giri, S; Pursnani, A; Botelho, M P F; Li, W; Koktzoglou, I

2015-11-23

Coronary magnetic resonance angiography (MRA) is usually obtained with a free-breathing navigator-gated 3D acquisition. Our aim was to develop an alternative breath-hold approach that would allow the coronary arteries to be evaluated in a much shorter time and without risk of degradation by respiratory motion artifacts. For this purpose, we implemented a breath-hold, non-contrast-enhanced, quiescent-interval slice-selective (QISS) 2D technique. Sequence performance was compared at 1.5 and 3 Tesla using both radial and Cartesian k-space trajectories. The left coronary circulation was imaged in six healthy subjects and two patients with coronary artery disease. Breath-hold QISS was compared with T2-prepared 2D balanced steady-state free-precession (bSSFP) and free-breathing, navigator-gated 3D bSSFP. Approximately 10 2.1-mm thick slices were acquired in a single ~20-s breath-hold using two-shot QISS. QISS contrast-to-noise ratio (CNR) was 1.5-fold higher at 3 Tesla than at 1.5 Tesla. Cartesian QISS provided the best coronary-to-myocardium CNR, whereas radial QISS provided the sharpest coronary images. QISS image quality exceeded that of free-breathing 3D coronary MRA with few artifacts at either field strength. Compared with T2-prepared 2D bSSFP, multi-slice capability was not restricted by the specific absorption rate at 3 Tesla and pericardial fluid signal was better suppressed. In addition to depicting the coronary arteries, QISS could image intra-cardiac structures, pericardium, and the aortic root in arbitrary slice orientations. Breath-hold QISS is a simple, versatile, and time-efficient method for coronary MRA that provides excellent image quality at both 1.5 and 3 Tesla. Image quality exceeded that of free-breathing, navigator-gated 3D MRA in a much shorter scan time. QISS also allowed rapid multi-slice bright-blood, diastolic phase imaging of the heart, which may have complementary value to multi-phase cine imaging. We conclude that, with further clinical

Vantage TitanTM 3T 3-tesla MRI system with enhanced serviceability and comfort

International Nuclear Information System (INIS)

Kanazawa, Hitoshi; Okamoto, Kazuya; Yamamoto, Takao

2011-01-01

Since 3-tesla magnetic resonance imaging (MRI) systems appeared on the market, in addition to their clinical usefulness a variety of issues have been pointed out in the clinical setting. The 3-tesla MRI system has therefore gained a reputation as a difficult system suitable only for hospital facilities including university hospitals that specialize in medical research. To rectify this situation, Toshiba Medical Systems Corporation has developed the Vantage Titan TM 3T, which is expected to not only improve the MRI examination environment, but also to be applicable to patients with claustrophobia and those with large physiques for whom MRI examination has not been appropriate until now, while maintaining the clinical usefulness of the 3-tesla MRI system. The Vantage Titan 3T system also incorporates the Pianissimo TM noise reduction mechanism, which has already been introduced in our 1.5-tesla MRI system and has been highly evaluated by the market. This reduces the stress of patients by providing a quieter and more open examination environment compared with conventional MRI systems. (author)

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

International Nuclear Information System (INIS)

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

2015-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-06-11

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

A Ball Lightning Model as a Possible Explanation of Recently Reported Cavity Lights

International Nuclear Information System (INIS)

Fryberger, D.

2009-01-01

The salient features of cavity lights, in particular, mobile luminous objects (MLO's), as have been experimentally observed in superconducting accelerator cavities, are summarized. A model based upon standard electromagnetic interactions between a small particle and the 1.5 GHz cavity excitation field is described. This model can explain some features of these data, in particular, the existence of particle orbits without wall contact. While this result is an important success for the model, it is detailed why the model as it stands is incomplete. It is argued that no avenues for a suitable extension of the model through established physics appear evident, which motivates an investigation of a model based upon a more exotic object, ball lightning. As discussed, further motivation derives from the fact that there are significant similarities in many of the qualitative features of ball lightning and MLO's, even though they appear in quite different circumstances and differ in scale by orders of magnitude. The ball lightning model, which incorporates electromagnetic charges and currents, is based on a symmetrized set of Maxwell's equations in which the electromagnetic sources and fields are characterized by a process called dyality rotation. It is shown that a consistent mathematical description of dyality rotation as a physical process can be achieved by adding suitable (phenomenological) current terms to supplement the usual current terms in the symmetrized Maxwell's equations. These currents, which enable the conservation of electric and magnetic charge, are called vacuum currents. It is shown that the proposed ball lightning model offers a good qualitative explanation of the perplexing aspects of the MLO data. Avenues for further study are indicated

A Ball Lightning Model as a Possible Explanation of Recently Reported Cavity Lights

Energy Technology Data Exchange (ETDEWEB)

Fryberger, David; /SLAC

2009-08-04

The salient features of cavity lights, in particular, mobile luminous objects (MLO's), as have been experimentally observed in superconducting accelerator cavities, are summarized. A model based upon standard electromagnetic interactions between a small particle and the 1.5 GHz cavity excitation field is described. This model can explain some features of these data, in particular, the existence of particle orbits without wall contact. While this result is an important success for the model, it is detailed why the model as it stands is incomplete. It is argued that no avenues for a suitable extension of the model through established physics appear evident, which motivates an investigation of a model based upon a more exotic object, ball lightning. As discussed, further motivation derives from the fact that there are significant similarities in many of the qualitative features of ball lightning and MLO's, even though they appear in quite different circumstances and differ in scale by orders of magnitude. The ball lightning model, which incorporates electromagnetic charges and currents, is based on a symmetrized set of Maxwell's equations in which the electromagnetic sources and fields are characterized by a process called dyality rotation. It is shown that a consistent mathematical description of dyality rotation as a physical process can be achieved by adding suitable (phenomenological) current terms to supplement the usual current terms in the symmetrized Maxwell's equations. These currents, which enable the conservation of electric and magnetic charge, are called vacuum currents. It is shown that the proposed ball lightning model offers a good qualitative explanation of the perplexing aspects of the MLO data. Avenues for further study are indicated.

Mathematical model governing laser-produced dental cavity

Science.gov (United States)

Yilbas, Bekir S.; Karatoy, M.; Yilbas, Z.; Karakas, Eyup S.; Bilge, A.; Ustunbas, Hasan B.; Ceyhan, O.

1990-06-01

Formation of dental cavity may be improved by using a laser beam. This provides nonmechanical contact, precise location of cavity, rapid processing and increased hygienity. Further examination of interaction mechanism is needed to improve the application of lasers in density. Present study examines the tenperature rise and thermal stress development in the enamel during Nd YAG laser irradiation. It is found that the stresses developed in the enamel is not sufficiently high enough to cause crack developed in the enamel.

An energy upgrade from TESLA to a high-energy μ+μ- collider

International Nuclear Information System (INIS)

Neuffer, D.; Edwards, H.; Finley, D.

1996-10-01

We discuss the possible extension of a TESLA 250X250 GeV SRF e + e - linear collider to a multi-TeV μ + μ - collider, by future addition of a muon source, return arcs for recirculation and a collider ring. The TESLA SRF systems are potentially also suitable for multiturn acceleration of muon bunches, and could be adapted for use in a recirculating μ-linac. Many problems and design issues would need to be resolved, and further study is needed

Rapid parametric mapping of the longitudinal relaxation time T1 using two-dimensional variable flip angle magnetic resonance imaging at 1.5 Tesla, 3 Tesla, and 7 Tesla.

Science.gov (United States)

Dieringer, Matthias A; Deimling, Michael; Santoro, Davide; Wuerfel, Jens; Madai, Vince I; Sobesky, Jan; von Knobelsdorff-Brenkenhoff, Florian; Schulz-Menger, Jeanette; Niendorf, Thoralf

2014-01-01

Visual but subjective reading of longitudinal relaxation time (T1) weighted magnetic resonance images is commonly used for the detection of brain pathologies. For this non-quantitative measure, diagnostic quality depends on hardware configuration, imaging parameters, radio frequency transmission field (B1+) uniformity, as well as observer experience. Parametric quantification of the tissue T1 relaxation parameter offsets the propensity for these effects, but is typically time consuming. For this reason, this study examines the feasibility of rapid 2D T1 quantification using a variable flip angles (VFA) approach at magnetic field strengths of 1.5 Tesla, 3 Tesla, and 7 Tesla. These efforts include validation in phantom experiments and application for brain T1 mapping. T1 quantification included simulations of the Bloch equations to correct for slice profile imperfections, and a correction for B1+. Fast gradient echo acquisitions were conducted using three adjusted flip angles for the proposed T1 quantification approach that was benchmarked against slice profile uncorrected 2D VFA and an inversion-recovery spin-echo based reference method. Brain T1 mapping was performed in six healthy subjects, one multiple sclerosis patient, and one stroke patient. Phantom experiments showed a mean T1 estimation error of (-63±1.5)% for slice profile uncorrected 2D VFA and (0.2±1.4)% for the proposed approach compared to the reference method. Scan time for single slice T1 mapping including B1+ mapping could be reduced to 5 seconds using an in-plane resolution of (2×2) mm2, which equals a scan time reduction of more than 99% compared to the reference method. Our results demonstrate that rapid 2D T1 quantification using a variable flip angle approach is feasible at 1.5T/3T/7T. It represents a valuable alternative for rapid T1 mapping due to the gain in speed versus conventional approaches. This progress may serve to enhance the capabilities of parametric MR based lesion detection and

PSpice modeling of broadband RF cavities for transient and frequency domain simulations

Energy Technology Data Exchange (ETDEWEB)

Harzheim, Jens [Institut fuer Theorie Elektromagnetischer Felder, Fachgebiet Beschleunigertechnik, TU Darmstadt (Germany)

2016-07-01

In the future accelerator facility FAIR, Barrier-Bucket Systems will play an important role for different longitudinal beam manipulations. As the function of this type of system is to provide single sine gap voltages, the components of the system have to operate in a broad frequency range. To investigate the different effects and to design the different system components, the whole Barrier-Bucket System is to be modeled in PSpice. While for low power signals, the system shows linear behavior, nonlinear effects arise at higher amplitudes. Therefore, simulations in both, frequency and time domain are needed. The highly frequency dependent magnetic alloy ring cores of the future Barrier-Bucket cavity have been mod eled in a first step and based on these models, the whole cavity was analyzed in PSpice. The simulation results show good agreement with former measurements.

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.

Modeling of cavity swelling-induced embrittlement in irradiated austenitic stainless steels

International Nuclear Information System (INIS)

Han, X.

2012-01-01

During long-time neutron irradiation occurred in Pressurized Water Reactors (PWRs), significant changes of the mechanical behavior of materials used in reactor core internals (made of 300 series austenitic stainless steels) are observed, including irradiation induced hardening and softening, loss of ductility and toughness. So far, much effect has been made to identify radiation effects on material microstructure evolution (dislocations, Frank loops, cavities, segregation, etc.). The irradiation-induced cavity swelling, considered as a potential factor limiting the reactor lifetime, could change the mechanical properties of materials (plasticity, toughness, etc.), even lead to a structure distortion because of the dimensional modifications between different components. The principal aim of the present PhD work is to study qualitatively the influence of cavity swelling on the mechanical behaviors of irradiated materials. A micromechanical constitutive model based on dislocation and irradiation defect (Frank loops) density evolution has been developed and implemented into ZeBuLoN and Cast3M finite element codes to adapt the large deformation framework. 3D FE analysis is performed to compute the mechanical properties of a polycrystalline aggregate. Furthermore, homogenization technique is applied to develop a Gurson-type model. Unit cell simulations are used to study the mechanical behavior of porous single crystals, by accounting for various effects of stress triaxiality, of void volume fraction and of crystallographic orientation, in order to study void effect on the irradiated material plasticity and roughness at polycrystalline scale. (author) [fr

Prominence mass supply and the cavity

Energy Technology Data Exchange (ETDEWEB)

Schmit, Donald J.; Innes, D. [Max Planck Institute for Solar System Research, D-37191 Katlenburg-Lindau (Germany); Gibson, S. [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Luna, M. [Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Karpen, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-12-20

A prevalent but untested paradigm is often used to describe the prominence-cavity system: the cavity is under-dense because it is evacuated by supplying mass to the condensed prominence. The thermal non-equilibrium (TNE) model of prominence formation offers a theoretical framework to predict the thermodynamic evolution of the prominence and the surrounding corona. We examine the evidence for a prominence-cavity connection by comparing the TNE model with diagnostics of dynamic extreme ultraviolet (EUV) emission surrounding the prominence, specifically prominence horns. Horns are correlated extensions of prominence plasma and coronal plasma which appear to connect the prominence and cavity. The TNE model predicts that large-scale brightenings will occur in the Solar Dynamics Observatory Atmospheric Imaging Assembly 171 Å bandpass near the prominence that are associated with the cooling phase of condensation formation. In our simulations, variations in the magnitude of footpoint heating lead to variations in the duration, spatial scale, and temporal offset between emission enhancements in the other EUV bandpasses. While these predictions match well a subset of the horn observations, the range of variations in the observed structures is not captured by the model. We discuss the implications of our one-dimensional loop simulations for the three-dimensional time-averaged equilibrium in the prominence and the cavity. Evidence suggests that horns are likely caused by condensing prominence plasma, but the larger question of whether this process produces a density-depleted cavity requires a more tightly constrained model of heating and better knowledge of the associated magnetic structure.

Prominence Mass Supply and the Cavity

Science.gov (United States)

Schmit, Donald J.; Gibson, S.; Luna, M.; Karpen, J.; Innes, D.

2013-01-01

A prevalent but untested paradigm is often used to describe the prominence-cavity system; the cavity is under-dense because it it evacuated by supplying mass to the condensed prominence. The thermal non-equilibrium (TNE) model of prominence formation offers a theoretical framework to predict the thermodynamic evolutin of the prominence and the surrounding corona. We examine the evidence for a prominence-cavity connection by comparing the TNE model and diagnostics of dynamic extreme ultraviolet (EUV) emission surrounding the prominence, specifically prominence horns. Horns are correlated extensions of prminence plasma and coronal plasma which appear to connect the prominence and cavity. The TNE model predicts that large-scale brightenings will occur in the Solar Dynamics Observatory Atmospheric Imaging Assembly 171 A badpass near he prominence that are associated with the cooling phase of condensation formation. In our simulations, variations in the magnitude of footpoint heating lead to variations in the duration, spatial scale, and temporal offset between emission enhancements in the other EUV bandpasses. While these predictions match well a subset of the horn observations, the range of variations in the observed structures is not captured by the model. We discuss the implications of one-dimensional loop simulations for the three-dimensional time-averaged equilibrium in the prominence and the cavity. Evidence suggests that horns are likely caused by condensing prominence plasma, but the larger question of whether this process produces a density-depleted cavity requires a more tightly constrained model of heating and better knowledge of the associated magnetic structure.

Modelling investigations of DBRs and cavities with photonic crystal holes for application in VCSELs

International Nuclear Information System (INIS)

Ivanov, P; Ho, Y-L D; Cryan, M J; Rorison, J

2012-01-01

We investigate the reflection spectra of distributed Bragg reflectors (DBRs) and DBR cavities with and without photonic crystal holes fabricated within them. A finite-difference time domain (FDTD) electromagnetic model which is considered to provide the exact solution of Maxwell equations is used as a reference model. Two simplified modelling approaches are compared to the FDTD results: an effective index model where the individual DBR constituent layers penetrated by holes possess an effective index and a spatial loss model where optical losses are introduced spatially where the holes are fabricated. Results of the FDTD and the spatial loss model show that optical loss determines the properties of an etched DBR and DBR cavity when the lattice constant of the holes of exceeds 1 μm and the hole depth is small. The spatial loss model compares well to the FDTD results for holes with a lattice period exceeding 1 μm. We also consider the realistic effect of angling the sides of the etched holes. (paper)

A compact multi-wire-layered secondary winding for Tesla transformer.

Science.gov (United States)

Zhao, Liang; Su, Jian-Cang; Li, Rui; Wu, Xiao-Long; Xu, Xiu-Dong; Qiu, Xu-Dong; Zeng, Bo; Cheng, Jie; Zhang, Yu; Gao, Peng-Cheng

2017-05-01

A compact multi-wire-layered (MWL) secondary winding for a Tesla transformer is put forward. The basic principle of this winding is to wind the metal wire on a polymeric base tube in a multi-layer manner. The tube is tapered and has high electrical strength and high mechanical strength. Concentric-circle grooves perpendicular to the axis of the tube are carved on the surface of the tube to wind the wire. The width of the groove is basically equal to the diameter of the wire so that the metal wire can be fixed in the groove without glue. The depth of the groove is n times of the diameter of the wire to realize the n-layer winding manner. All the concentric-circle grooves are connected via a spiral groove on the surface of the tube to let the wire go through. Compared with the traditional one-wire-layered (OWL) secondary winding for the Tesla transformer, the most conspicuous advantage of the MWL secondary winding is that the latter is compact with only a length of 2/n of the OWL. In addition, the MWL winding has the following advantages: high electrical strength since voids are precluded from the surface of the winding, high mechanical strength because polymer is used as the material of the base tube, and reliable fixation in the Tesla transformer as special mechanical connections are designed. A 2000-turn MWL secondary winding is fabricated with a winding layer of 3 and a total length of 1.0 m. Experiments to test the performance of this winding on a Tesla-type pulse generator are conducted. The results show that this winding can boost the voltage to 1 MV at a repetition rate of 50 Hz reliably for a lifetime longer than 10 4 pulses, which proves the feasibility of the MWL secondary winding.

Homogeneous nonequilibrium critical flashing flow with a cavity flooding model

International Nuclear Information System (INIS)

Lee, S.Y.; Schrock, V.E.

1989-01-01

The primary purpose of the work presented here is to describe the model for pressure undershoot at incipient flashing in the critical flow of straight channels (Fanno-type flow) for subcooled or saturated stagnation conditions on a more physical basis. In previous models, a modification of the pressure undershoot prediction of Alamgir and Lienhard was used. Their method assumed nucleation occurs on the bounding walls as a result of molecular fluctuations. Without modification it overpredicts the pressure undershoot. In the present work the authors develop a mechanistic model for nucleation from wall cavities. This physical concept is more consistent with experimental data

Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments

CERN Document Server

Przygoda, K

2011-01-01

This dissertation covers the recent research and development (R&D) activities of control systems for the fast frequency tuners of TESLA cavities and predicts the implications foreseen for large scale machines such as the FLASH and the planned XFEL. In particular, the framework of the presented activities is the effort toward the: 1. R&D of the driving circuit, 2. R&D of the control algorithm, 3. R&D of the control system. The main result of these activities is the permanent installation of the target piezo control system and its commissioning for 40 cavities divided into 5 accelerating modules at the DESY FLASH facility. The author’s contribution was the study of possible designs of high-voltage, high-current power amplifiers, used for driving the fast frequency tuners, shows that several parameters of such a device needs to be considered. The most important parameter is the input and output power estimation. This arises from the fact that the estimation is the most crucial issue for both po...

Development of superconducting cavities at JAERI

International Nuclear Information System (INIS)

Ouchi, N.

2001-01-01

Development of superconducting (SC) cavities is continued for the high intensity proton accelerator in JAERI. In FY-1999, we carried out R and D work; (1) 2nd vertical test of β=0.886 single-cell cavity, (2) vertical test for observation of Q-disease without heat treatment after electropolishing, (3) vertical test of β=0.5 5-cell cavity, (4) pretuning, surface treatment and vertical test of β=0.886 5-cell cavity, (5) pulsed operation of β=0.886 single-cell cavity in the vertical test to confirm the validity of a new model calculation. This paper describes the present status of the R and D work for the SC cavities in JAERI. (author)

Design study of 15-Tesla RHQT Nb3Al block type dipole magnet

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Ambrosio, G.; Barzi, E.; Kashikin, V.; Kikuchi, A.; Novitski, I.; Takeuchi, T.; Wake, M.; Zlobin, A.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

2005-09-01

The design study of the block type 15-Tesla RHQT Nb{sub 3}Al dipole magnet, and its merits over Nb{sub 3}Sn magnets are presented. The copper stabilized RHQT Nb{sub 3}Al strand is now becoming commercially available for the application to the accelerator magnets. A 1 mm diameter RHQT Nb{sub 3}Al strand with filament size about 50 {mu}, non-copper Jc about 1000 A/mm{sup 2} at 15 Tesla at 4.2K, copper ratio of 50%, can now be produced over several hundred meters. The stress and strain characteristics of the Nb{sub 3}Al strand are superior to the Nb{sub 3}Sn strand. Another advantage is that it can tolerate a longitudinal strain up to 0.55%. The RHQT Nb{sub 3}Al Rutherford cable will have less chance of contamination of the stabilizer, compared to Nb{sub 3}Sn cable. These characteristics of the RHQT Nb{sub 3}Al will be beneficial for designing and producing 15-Tesla dipole magnets. An example 15-Tesla magnet cross section, utilizing the RHQT Nb{sub 3}Sn strand is presented. A systematic investigation on RHQT Nb{sub 3}Al strands, its Rutherford cables, and building a small racetrack magnet for cable testing are proposed.

Note: A high-energy-density Tesla-type pulse generator with novel insulating oil

Science.gov (United States)

Liu, Sheng; Su, Jiancang; Fan, Xuliang

2017-09-01

A 10-GW high-energy-density Tesla-type pulse generator is developed with an improved insulating liquid based on a modified Tesla pulser—TPG700, of which the pulse forming line (PFL) is filled with novel insulating oil instead of transformer oil. Properties of insulating oil determining the stored energy density of the PFL are analyzed, and a criterion for appropriate oil is proposed. Midel 7131 is chosen as an application example. The results of insulating property experiment under tens-of-microsecond pulse charging demonstrate that the insulation capability of Midel 7131 is better than that of KI45X transformer oil. The application test in Tesla pulser TPG700 shows that the output power is increased to 10.5 GW with Midel 7131. The output energy density of TPG700 increases for about 60% with Midel 7131.

Cavity magnon polaritons with lithium ferrite and three-dimensional microwave resonators at millikelvin temperatures

Science.gov (United States)

Goryachev, Maxim; Watt, Stuart; Bourhill, Jeremy; Kostylev, Mikhail; Tobar, Michael E.

2018-04-01

Single crystal lithium ferrite (LiFe) spheres of sub-mm dimension are examined at mK temperatures, microwave frequencies, and variable dc magnetic field, for use in hybrid quantum systems and condensed matter and fundamental physics experiments. Strong coupling regimes of the photon-magnon interaction (cavity magnon polariton quasiparticles) were observed with coupling strength of up to 250 MHz at 9.5 GHz (2.6%) with magnon linewidths of order 4 MHz (with potential improvement to sub-MHz values). We show that the photon-magnon coupling can be significantly improved and exceed that of the widely used yttrium iron garnet crystal, due to the small unit cell of LiFe, allowing twice the spins per unit volume. Magnon mode softening was observed at low dc fields and, combined with the normal Zeeman effect, creates magnon spin-wave modes that are insensitive to first-order magnetic-field fluctuations. This effect is observed in the Kittel mode at 5.5 GHz (and another higher order mode at 6.5 GHz) with a dc magnetic field close to 0.19 tesla. We show that if the cavity is tuned close to this frequency, the magnon polariton particles exhibit an enhanced range of strong coupling and insensitivity to magnetic field fluctuations with both first-order and second-order insensitivity to magnetic field as a function of frequency (double magic point clock transition), which could potentially be exploited in cavity QED experiments.

Computer codes for RF cavity design

International Nuclear Information System (INIS)

Ko, K.

1992-08-01

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

Occipital cortical proton MRS at 4 Tesla in human moderate MDMA polydrug users

OpenAIRE

Cowan, Ronald L.; Bolo, Nicolas R.; Dietrich, Mary; Haga, Erica; Lukas, Scott E.; Renshaw, Perry F.

2007-01-01

The recreational drug MDMA (3,4, methylenedioxymethamphetamine; sold under the street name of Ecstasy) is toxic to serotonergic axons in some animal models of MDMA administration. In humans, MDMA use is associated with alterations in markers of brain function that are pronounced in occipital cortex. Among neuroimaging methods, magnetic resonance spectroscopy (MRS) studies of brain metabolites N-acetylaspartate (NAA) and myoinositol (MI) at a field strength of 1.5 Tesla (T) reveal inconsistent...

Heat or mass transfer from an open cavity

NARCIS (Netherlands)

Kuiken, H.K.

1978-01-01

This paper presents a mathematical model for heat or mass transfer from an open cavity. It is assumed that the Péclet number, based on conditions at the cavity, and the Prandtl number are both large. The model assumes heat- or mass-transfer boundary layers at the rim of the cavity vortex flow. Heat

Diffusion-weighted MR imaging of the normal pancreas: reproducibility and variations of apparent diffusion coefficient measurement at 1.5- and 3.0-Tesla.

Science.gov (United States)

Barral, M; Soyer, P; Ben Hassen, W; Gayat, E; Aout, M; Chiaradia, M; Rahmouni, A; Luciani, A

2013-04-01

To evaluate reproducibility and variations in apparent diffusion coefficient (ADC) measurement in normal pancreatic parenchyma at 1.5- and 3.0-Tesla and determine if differences may exist between the four pancreatic segments. Diffusion-weighted MR imaging of the pancreas was performed at 1.5-Tesla in 20 patients and at 3.0-Tesla in other 20 patients strictly matched for gender and age using the same b values (0, 400 and 800s/mm(2)). Two independent observers placed regions of interest within the four pancreatic segments to measure ADC at both fields. Intra- and inter-observer agreement in ADC measurement was assessed using Bland-Altman analysis and comparison between ADC values obtained at both fields using non-parametrical tests. There were no significant differences in ADC between repeated measurements and between ADC obtained at 1.5-Tesla and those at 3.0-Tesla. The 95% limits of intra-observer agreement between ADC were 2.3%-22.7% at 1.5-Tesla and 1%-24.2% at 3.0-Tesla and those for inter-observer agreement between 1.9%-14% at 1.5-Tesla and 8%-25% at 3.0-Tesla. ADC values were similar in all pancreatic segments at 3.0-T whereas the tail had lower ADC at 1.5-Tesla. ADC measurement conveys high degrees of intra- and inter-observer reproducibility. ADC have homogeneous distribution among the four pancreatic segments at 3.0-Tesla. Copyright © 2012 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

Investigating the probability of detection of typical cavity shapes through modelling and comparison of geophysical techniques

Science.gov (United States)

James, P.

2011-12-01

With a growing need for housing in the U.K., the government has proposed increased development of brownfield sites. However, old mine workings and natural cavities represent a potential hazard before, during and after construction on such sites, and add further complication to subsurface parameters. Cavities are hence a limitation to certain redevelopment and their detection is an ever important consideration. The current standard technique for cavity detection is a borehole grid, which is intrusive, non-continuous, slow and expensive. A new robust investigation standard in the detection of cavities is sought and geophysical techniques offer an attractive alternative. Geophysical techniques have previously been utilised successfully in the detection of cavities in various geologies, but still has an uncertain reputation in the engineering industry. Engineers are unsure of the techniques and are inclined to rely on well known techniques than utilise new technologies. Bad experiences with geophysics are commonly due to the indiscriminate choice of particular techniques. It is imperative that a geophysical survey is designed with the specific site and target in mind at all times, and the ability and judgement to rule out some, or all, techniques. To this author's knowledge no comparative software exists to aid technique choice. Also, previous modelling software limit the shapes of bodies and hence typical cavity shapes are not represented. Here, we introduce 3D modelling software (Matlab) which computes and compares the response to various cavity targets from a range of techniques (gravity, gravity gradient, magnetic, magnetic gradient and GPR). Typical near surface cavity shapes are modelled including shafts, bellpits, various lining and capping materials, and migrating voids. The probability of cavity detection is assessed in typical subsurface and noise conditions across a range of survey parameters. Techniques can be compared and the limits of detection distance

Estimating cavity tree and snag abundance using negative binomial regression models and nearest neighbor imputation methods

Science.gov (United States)

Bianca N.I. Eskelson; Hailemariam Temesgen; Tara M. Barrett

2009-01-01

Cavity tree and snag abundance data are highly variable and contain many zero observations. We predict cavity tree and snag abundance from variables that are readily available from forest cover maps or remotely sensed data using negative binomial (NB), zero-inflated NB, and zero-altered NB (ZANB) regression models as well as nearest neighbor (NN) imputation methods....

Computer codes for RF cavity design

International Nuclear Information System (INIS)

Ko, K.

1992-01-01

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

HF power couplers for pulsed superconducting cavity resonators; Coupleurs de puissance HF pour cavites supraconductrices en mode pulse

Energy Technology Data Exchange (ETDEWEB)

Jenhani, Hassen [Laboratoire de l' Accelerateur Lineaire, IN2P3-CNRS et Universite de Paris-Sud, BP 34, F-91898 Orsay Cedex (France)

2006-11-15

Recent years have seen an impressive improvement in the accelerating gradients obtained in superconducting cavities. Consequently, such cavities have become attractive candidates for large superconducting linear accelerator projects such as the European XFEL and the International Linear Collider (ILC). As a result, there is a strong interest in reducing RF conditioning time and improving the performance of the input power couplers for these cavities. The so-called TTF-III input power coupler, adopted for the XFEL superconducting RF cavities are complex components. In order to better understand the behavior of this component we have performed a series of experiments on a number of such couplers. Initially, we developed a fully automated RF high power test stand for coupler conditioning procedure. Following this, we performed a series of coupler conditioning tests. This has allowed the study of the coupler behavior during processing. A number of experiments were carried out to evaluate the in-situ baking effect on the conditioning time. Some of the conditioned couplers were sent to DESY in order to be tested on 9-cells TESLA cavities under cryogenic conditions. These tests have shown that the couplers in no way limit the cavity performance, even up to gradients of 35 MV/m. The main objective of our coupler studies was the reduction of their conditioning time, which represents one of the most important criteria in the choice of coupler for high energy linacs. Excellent progress in reducing the conditioning time has been demonstrated by making appropriate modifications to the conditioning procedure. Furthermore, special attention was paid to electron generation processes in the couplers, via multipacting. Simulations of this process were made on both the TTF-III coupler and on a new coupler prototype, TTF-V. Experiments aimed at suppressing multipacting were also successfully achieved by using a DC bias on the inner conductor of the co-axial coupler. (author)

Jakob Narkiewicz-Jodko-Tesla ``Predecessor''

Science.gov (United States)

Samuilov, Vladimir; Kiselev, Vladimir

2014-03-01

Prof. Jakob Narkiewicz-Jodko (1947-1905) is a bright figure in the history of science of the XIXth century. His major discoveries are: Electrography - the method of the visualization of electric discharge from the bodies due to the application of high strength and high frequency electric fields, and one of the first observations of the propagation of the electromagnetic waives and information transfer over the distances. We review Prof. Jakob Narkiewicz-Jodko's research results and explain our point why we consider him as the predecessor of Nikola Tesla.

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.

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

RHQT Nb3Al 15-Tesla magnet design study

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Ambrosio, G.; Barzi, E.; Kashikin, V.; Kikuchi, A.; Novitski, I.; Takeuchi, T.; Wake, M.; Zlobin, A.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

2005-09-01

Feasibility study of 15-Tesla dipole magnets wound with a new copper stabilized RHQT Nb{sub 3}Al Rutherford cable is presented. A new practical long copper stabilized RHQT Nb{sub 3}Al strand is presented, which is being developed and manufactured at the National Institute of Material Science (NIMS) in Japan. It has achieved a non-copper J{sub c} of 1000A/mm{sup 2} at 15 Tesla at 4.2K, with a copper over non-copper ratio of 1.04, and a filament size less than 50 microns. For this design study a short Rutherford cable with 28 Nb{sub 3}Al strands of 1 mm diameter will be fabricated late this year. The cosine theta magnet cross section is designed using ROXIE, and the stress and strain in the coil is estimated and studied with the characteristics of the Nb{sub 3}Al strand. The advantages and disadvantages of the Nb{sub 3}Al cable are compared with the prevailing Nb{sub 3}Sn cable from the point of view of stress-strain, J{sub c}, and possible degradation of stabilizer due to cabling. The Nb{sub 3}Al coil of the magnet, which will be made by wind and react method, has to be heat treated at 800 degree C for 10 hours. As preparation for the 15 Tesla magnet, a series of tests on strand and Rutherford cables are considered.

Off Like a Rocket: A Media Discourse Analysis of Tesla Motor Corporation

OpenAIRE

McKay, Jordan

2016-01-01

Energy and transportation are topics of great importance to global sustainable development.  Tesla Motor Corporation is an electric vehicle company with the objective to “accelerate the world’s transition to sustainable energy” (Musk, 2016).  This thesis, a media discourse analysis, examines media texts concerning Tesla Motors to provide a better understanding of the company’s hitherto success in penetrating the automotive market.  Qualitative analyses of text were utilized to first define th...

Habitat suitability models for cavity-nesting birds in a postfire landscape

Science.gov (United States)

Robin E. Russell; Victoria A. Saab; Jonathan G. Dudley

2007-01-01

Models of habitat suitability in postfire landscapes are needed by land managers to make timely decisions regarding postfire timber harvest and other management activities. Many species of cavity-nesting birds are dependent on postfire landscapes for breeding and other aspects of their life history and are responsive to postfire management activities (e.g., timber...

Modeling and experimental verification of laser self-mixing interference phenomenon with the structure of two-external-cavity feedback

Science.gov (United States)

Chen, Peng; Liu, Yuwei; Gao, Bingkun; Jiang, Chunlei

2018-03-01

A semiconductor laser employed with two-external-cavity feedback structure for laser self-mixing interference (SMI) phenomenon is investigated and analyzed. The SMI model with two directions based on F-P cavity is deduced, and numerical simulation and experimental verification were conducted. Experimental results show that the SMI with the structure of two-external-cavity feedback under weak light feedback is similar to the sum of two SMIs.

Design and Fabrication Study on the TESLA500 Superconducting Magnet Package

Energy Technology Data Exchange (ETDEWEB)

Garcia-Tabares, L.; Toral, F.; Calero, J.; Abramian, P.; Iturbe, R.; Etxeandia, J.; Lucia, C.; Landete, R.; Gomez, J.

2001-07-01

An international collaboration at DESY is currently studying the possibilities of a new type of particle accelerator: the superconducting linear collider (1). Developed under the project name TESLA, which stands for TeV Energy Superconducting Linear Accelerator, the facility would be placed in a 33 km long tunnel and would work at the energy range of 0.5 to 0.8 TeV. TESLA opens up new horizons not only as a particle accelerator because it can be also used to generate laser-type X-ray beams: the accelerated electrons would be guided through a refined system of magnetic fields to form a Free Electron Laser (FEL). This study is about one of the components of the accelerator: the magnet package. A technical design of this device and a cost estimate of the series production have been performed. The present report should be understood as a Spanish contribution to the TESLA project. The study has been lead by CIEMAT (Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas) [2], and several Spanish companies have also been involved: ANTEC, JEMA and INGOVI. Special thanks are given to the Oficina de Ciencia y Tecnologia, which has granted this work. (Author) 16 refs.

Prospects for 6- to 10-Tesla magnets for a Tevatron upgrade

International Nuclear Information System (INIS)

Mantsch, P.M.

1989-01-01

This paper reports on prospects for 6- to 10-tesla magnets for a Teratron upgrade. The first SSC physics is at least 10 years away. An upgrade of the Fermilab Tevatron will ensure the continuity of a vigorous high-energy physics program until the SSC turns on. Three basic proposals are under consideration: (1) bar pp at 3 x 10 31 --Increase luminosity by improvements to the bar p source. (2) p bar p at 1 TeV and 2 x 10 32 --Move the main ring to a new tunnel, build a second Tevatron ring. (3) bar pp > 1.5 TeV and 7 x 10 30 --Replace the Tevatron with a higher energy ring. The last two options require new higher-field magnets. The second option requires about a hundred 6.6-tesla dipoles in addition to a ring of Tevatron-strength (4.4-T) magnets. These higher-field magnets are necessary in both rings to lengthen the straight sections in order to realize the collision optics. The third option requires a ring of magnets of 6.6 T or slightly higher to replace the present Tevatron plus a number of special 8- to 9-tesla magnets

Design and Fabrication Study on the TESLA500 Superconducting Magnet Package

International Nuclear Information System (INIS)

Garcia-Tabares, L.; Toral, F.; Calero, J.; Abramian, P.; Iturbe, R.; Etxeandia, J.; Lucia, C.; Landete, R.; Gomez, J.

2001-01-01

An international collaboration at DESY is currently studying the possibilities of a new type of particle accelerator: the superconducting linear collider (1). Developed under the project name TESLA, which stands for TeV Energy Superconducting Linear Accelerator, the facility would be placed in a 33 km long tunnel and would work at the energy range of 0.5 to 0.8 TeV. TESLA opens up new horizons not only as a particle accelerator because it can be also used to generate laser-type X-ray beams: the accelerated electrons would be guided through a refined system of magnetic fields to form a Free Electron Laser (FEL). This study is about one of the components of the accelerator: the magnet package. A technical design of this device and a cost estimate of the series production have been performed. The present report should be understood as a Spanish contribution to the TESLA project. The study has been lead by CIEMAT (Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas) [2], and several Spanish companies have also been involved: ANTEC, JEMA and INGOVI. Special thanks are given to the Oficina de Ciencia y Tecnologia, which has granted this work. (Author) 16 refs

Structural analysis of TFTR TF coils and support structure for 6 Tesla operation

International Nuclear Information System (INIS)

Zatz, I.J.; Cargulia, G.; Lontai, L.

1995-01-01

The Tokamak Fusion Test Reactor (TFTR), which has been on line since December 1982, has successfully operated at its design Toroidal Field (TF) of 5.2 Tesla. Analysis of test data has indicated that the measured peak D-D neutron power in supershots may be scaled to the fourth power of TF field. Increasing the TF field to 6 Tesla provides the opportunity to explore the possibility of improving the D-T fusion yield, with the use of tritium. This increase in TF field from 5.2 to 6.0 Tesla increases the centering force by 33% and the out-of-plane force by 15% over previous peak operating levels. To examine the impact of the increase in loads on the TF coil, case and supporting structure, finite element analyses (FEA) were performed with and without the presence of loose bolts in the TF case. Note that the loose bolts comprise a fraction of the total number of bolts fastening the TF case sidewalls to the inner and outer rings of the case. Extensive analysis was performed using the FEA results in conjunction with supplementary calculations. Results are presented for the TF case, bolts, copper conductors, insulation, and supporting structure which indicate that the TF coils can successfully operate at 6 Tesla for a reasonable number of pulses

Multipartite quantum correlations among atoms in QED cavities

Science.gov (United States)

Batle, J.; Farouk, A.; Tarawneh, O.; Abdalla, S.

2018-02-01

We study the nonlocality dynamics for two models of atoms in cavity quantum electrodynamics (QED); the first model contains atoms in a single cavity undergoing nearest-neighbor interactions with no initial correlation, and the second contains atoms confined in n different and noninteracting cavities, all of which were initially prepared in a maximally correlated state of n qubits corresponding to the atomic degrees of freedom. The nonlocality evolution of the states in the second model shows that the corresponding maximal violation of a multipartite Bell inequality exhibits revivals at precise times, defining, nonlocality sudden deaths and nonlocality sudden rebirths, in analogy with entanglement. These quantum correlations are provided analytically for the second model to make the study more thorough. Differences in the first model regarding whether the array of atoms inside the cavity is arranged in a periodic or open fashion are crucial to the generation or redistribution of quantum correlations. This contribution paves the way to using the nonlocality multipartite correlation measure for describing the collective complex behavior displayed by slightly interacting cavity QED arrays.

A 4-Tesla superconducting whole-body magnet for MR imaging and spectroscopy

International Nuclear Information System (INIS)

Vetter, J.; Ries, G.; Reichert, T.

1988-01-01

Since January 87 a 4 tesla MR magnet with a 1.25 m diameter warm bore is in operation at the Siemens Research Laboratories. The magnet weighing 10 tons is part of a whole-body MR device devoted to in-vivo research studies at magnetic fields significantly higher than 2 tesla; the highest field strength presently used in standard MR whole-body systems. The stored energy of the adiabatically stable six-coil system is 39 MJ at 4 tesla. The rated current is 376 A. Superconducting and resistive shim-coils together with iron shims reduce the bare magnet inhomogeneity of 100 ppm down to less than 5 ppm in a 50 cm diameter spherical volume. The magnet operates in persistent mode with the current leads retracted. The field drift is less than 3 x 10/sup -8//h. A small helium refrigerator is used to cool both the two radiation shields of the cryostat and the current leads and to reliquify the evaporating helium gas. Results of coil design, analysis of forces and stresses, quench protection, cryostat design and magnet operation are reported

Nikola Tesla - genije koji je premostio vekove

Directory of Open Access Journals (Sweden)

Vladimir T. Ristić

2006-07-01

Full Text Available Ispisujući prve stranice svoje obimne knjige o životnom putu Nikole Tesle, američki pisac Džon Oí Nil kaže: Tesla je bio mislilac i pronalazač najvišeg reda, onaj što mišljenjem, a ne slučajem, dolazi do otkrića, dok mu eksperiment služi samo za potvrdu njegove teze. On je bio i matematičar, znao je bezbroj formula napamet, tako da se najčešće nije morao služiti priručnicima; osim toga, imao je najsolidnije tehničko obrazovanje, što je, na primer, Edisonu nedostajalo. Nikola Tesla je osnovno školovanje započeo u rodnom Smiljanu, a nastavio i dovršio u Gospiću gde se sa roditeljima, posle smrti starijeg brata, preselio. Gimnaziju je upisao u Karlovcu. Bila je to ugledna škola, a u profesoru fizike Nikola je imao izuzetnog pedagoga, koji je svojim đacima umeo vrlo vešto da dočara čak i ono što je u fizici teško razumljivo.

Micro-Cavity Fluidic Dye Laser

DEFF Research Database (Denmark)

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

2003-01-01

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

Superstructures: First Cold Test and Future Applications

International Nuclear Information System (INIS)

J. Sekutowicz; C Albrecht; V Ayvazyan; R Bandelmann; T Buttner; P Castro; S Choroba; J Eschke; B Faatz; A Gossel; K Honkavaara; B Horst; J Iverson; K Jensch; H Kaiser; R Kammering; G Kreps; D Kostin; J Lorkiewicz; R Lange; A Matheisen; W -D Moller; H -B Peters; D Proch; K Rehlich; H Schlarb; S Schrieber; D Reschke; S Simrock; W Singer; X Singer; K Twarowski; T Weichert; M Wojtkiewicz; G Wendt; K Zapfe; M Liepe; M Huening; M Ferrario; E Plawski; C Pagani; P Kneisel; G Wu; N Baboi; C Thomas; H Chen; W Huang; C Tang; S Zheng

2003-01-01

Superstructures, chains of superconducting multi-cell cavities (subunits) connected by e/2 long tube(s) have been proposed as an alternative layout for the TESLA main accelerator [1]. After three years of preparation, two superstructures, each made of two weakly coupled superconducting 7-cell subunits driven by a single Fundamental Power Coupler (FPC), have been installed in the Tesla Test Facility linac for beam tests. Energy stability, HOM damping, frequency and field adjustment methods were tested. The measured results confirme Superstructures, chains of superconducting multi-cell cavities (subunits) connected by e/2 long tube(s) have been proposed as an alternative layout for the TESLA main accelerator [1]. After three years of preparation, two superstructures, each made of two weakly coupled superconducting 7-cell subunits driven by a single Fundamental Power Coupler (FPC), have been installed in the Tesla Test Facility linac for beam tests. Energy stability, HOM damping, frequency and field adjustment methods were tested. The measured results confirmed expectation on the superstructure performance and proved that an alternative layout for the 800 GeV upgrade of the TESLA collider is feasible. We report on the test and give here an overview of its results. The tests confirmed very good damping of HOMs in superstructures and thus has opened a possible new application of this concept to high current energy recovery machines. We have built two 1.5 GHz copper models of two superstructures: 2x5-cells and 2x2-cells to prove further improvement of HOM damping. This contribution presents also measured results on these models. d expectations on the superstructure performance and proved that an alternative layout for the 800 GeV upgrade of the TESLA collider is feasible. We report on the test and give here an overview of its results

Voltage distribution in tapered winding of tesla-transformer during discharge process of PFL

International Nuclear Information System (INIS)

Xin Jiaqi; Chang Anbi; Li Mingjia; Kang Qiang

2007-01-01

The operation principle of integral construction of Tesla transformer and PFL was investigated in Tesla-transformer-type accelerator. Experiment was carried out on Tesla transformer's secondary winding to study the impulse voltage distribution while PFL was discharging. The regularities of turn-ground voltage distribution and interturn voltage distribution were summarized. Voltage distribution within PFL was calculated and it was compared with the experimental result. Structural winding of parallel coils in the head, parallel coils in the end and shading ring were used to improve voltage distribution and that was testified by experiment. The results indicate that taper winding doesn't effect electric field within PFL, the turn-ground voltage appears linearly, the interturn voltage fluctuates seriously and it is the biggest in head of winding. The three optimized methods help to depress oscillation, the structural winding of parallel coils in the head decreases the interturn voltage in head of winding remark-ably and the parallel coils in the end decrease the interturn voltage in the end. (authors)

Soil moisture determination with Tesla NZK 203 neutron gage

International Nuclear Information System (INIS)

Hally, J.

1977-01-01

Soil moisture was measured using the NZK 203 neutron probe manufactured by Tesla Premysleni. The individual measuring sites were spaced at a distance of 100 m. The NZK 203 set consists of a NPK 202 moisture gage and a NSK 301 scintillation detector and features the following specifications: moisture density measuring range 20 to 500 kg/m 3 , 241 Am-Be fast neutron source having a neutron flux of 7.5x10 4 n.sec -1 +-10%, operating temperature -10 to +45 degC. The measured counting rate was primarily affected by the statistical fluctuation of ionizing radiation and by instrument instability. In order that these effects should be limited each measurement was repeated 10 times with the optimum measurement time at an interval of 20 to 100 sec. The NZK 203 Tesla set was proven to be suitable for rapid and reproducible determination of moisture profiles. (J.P.)

MR imaging of the prostate at 3 Tesla: comparison of an external phased-array coil to imaging with an endorectal coil at 1.5 Tesla.

Science.gov (United States)

Sosna, Jacob; Pedrosa, Ivan; Dewolf, William C; Mahallati, Houman; Lenkinski, Robert E; Rofsky, Neil M

2004-08-01

To qualitatively compare the image quality of torso phased-array 3-Tesla (3T) imaging of the prostate with that of endorectal 1.5-Tesla imaging. Twenty cases of torso phased-array prostate imaging performed at 3-Tesla with FSE T2 weighted images were evaluated by two readers independently for visualization of the posterior border (PB), seminal vesicles (SV), neurovascular bundles (NVB), and image quality rating (IQR). Studies were performed at large fields of view(FOV) (25 cm) (14 cases) (3TL) and smaller FOV (14 cm) (19 cases) (3TS). A comparison was made to 20 consecutive cases of 1.5-T endorectal evaluation performed during the same time period.Results. 3TL produced a significantly better image quality compared with the small FOV for PB (P = .0001), SV (P =.0001), and IQR (P = .0001). There was a marginally significant difference within the NVB category (P = .0535). 3TL produced an image of similar quality to image quality at 1.5 T for PB (P = .3893), SV (P = .8680), NB (P = .2684), and IQR (P = .8599). Prostate image quality at 3T with a torso phased-array coil can be comparable with that of endorectal 1.5-T imaging. These findings suggest that additional options are now available for magnetic resonance imaging of the prostate gland.

Development and manufacturing of a Nb$_{3}$Sn quadrupole magnet Model at CEA/Saclay for TESLA Interaction Region

CERN Document Server

Durante, Maria; Fratini, M; Leboeuf, D; Segreti, M; Védrine, Pierre; 10.1109/TASC.2004.829129

2004-01-01

One possible application of Nb/sub 3/Sn, whose superconducting properties far exceed those of NbTi, is the fabrication of short and powerful quadrupole magnets for the interaction regions of large particle accelerators. In some projects, as in the future linear collider TESLA, the quadrupole magnets are inside the detector solenoid and must operate in its background field. This situation gives singular Lorentz force distribution in the ends of the magnet. To learn about Nb/sub 3/Sn technology, evaluate fabrication techniques and test the interaction with a solenoidal field, DAPNIA /SACM at CEA/Saclay has started the manufacturing of a 1-m-long, 56- mm-single-aperture quadrupole magnet model. The model relies on the same coil geometry as the LHC arc quadrupole magnets, but has no iron yoke. It will produce a nominal field gradient of 211 T/m at 11,870 A. The coils are wound from Rutherford-type cables insulated with glass fiber tape, before being heat-treated and vacuum-impregnated with epoxy resin. Laminated,...

Modeling of Coupled Nano-Cavity Lasers

DEFF Research Database (Denmark)

Skovgård, Troels Suhr

-of-states and it is argued that Purcell enhancement should also be included in stimulated recombination term, contrary to the common practice in the literature. It is shown that for quantum well devices, the Purcell enhancement is effectively independent of the cavity quality factor due to the broad electronic density......-of-states relative to the optical density-of-states. The low effective Purcell eect for quantum well devices limits the highest possible modulation bandwidth to a few tens of gigahertz, which is comparable to the performance of conventional diode lasers. Compared to quantum well devices, quantum dot devices have...... is useful for design of coupled systems. A tight-binding description for coupled nanocavity lasers is developed and employed to investigate the phase-locking behavior for the system of two coupled cavities. Phase-locking is found to be critically dependent on exact parameter values and to be dicult...

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.

In vitro assessment of MRI issues at 3-Tesla for a breast tissue expander with a remote port.

Science.gov (United States)

Linnemeyer, Hannah; Shellock, Frank G; Ahn, Christina Y

2014-04-01

A patient with a breast tissue expander may require a diagnostic assessment using magnetic resonance imaging (MRI). To ensure patient safety, this type of implant must undergo in vitro MRI testing using proper techniques. Therefore, this investigation evaluated MRI issues (i.e., magnetic field interactions, heating, and artifacts) at 3-Tesla for a breast tissue expander with a remote port. A breast tissue expander with a remote port (Integra Breast Tissue Expander, Model 3612-06 with Standard Remote Port, PMT Corporation, Chanhassen, MN) underwent evaluation for magnetic field interactions (translational attraction and torque), MRI-related heating, and artifacts using standardized techniques. Heating was evaluated by placing the implant in a gelled-saline-filled phantom and MRI was performed using a transmit/receive RF body coil at an MR system reported, whole body averaged specific absorption rate of 2.9-W/kg. Artifacts were characterized using T1-weighted and GRE pulse sequences. Magnetic field interactions were not substantial and, thus, will not pose a hazard to a patient in a 3-Tesla or less MRI environment. The highest temperature rise was 1.7°C, which is physiologically inconsequential. Artifacts were large in relation to the remote port and metal connector of the implant but will only present problems if the MR imaging area of interest is where these components are located. A patient with this breast tissue expander with a remote port may safely undergo MRI at 3-Tesla or less under the conditions used for this investigation. These findings are the first reported at 3-Tesla for a tissue expander. Copyright © 2014 Elsevier Inc. All rights reserved.

Investigation of superconducting niobium 1170 MHz cavities

International Nuclear Information System (INIS)

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

1988-01-01

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

Synchronic, optical transmission data link integrated with FPGA circuits (for TESLA LLRF control system)

Energy Technology Data Exchange (ETDEWEB)

Zielinski, J.S.

2006-07-15

The X-ray free-electron laser X-FEL that is being planned at the DESY research center in cooperation with European partners will produce high-intensity ultra-short X-ray flashes with the properties of laser light. This new light source, which can only be described in terms of superlatives, will open up a whole range of new possibilities for the natural sciences. It could also offer very promising opportunities for industrial users. SIMCON (SIMulator and CONtroller) is the project of the fast, low latency digital controller dedicated to the LLRF1 system in VUV FEL experiment It is being developed by the ELHEP2 group in the Institute of Electronic Systems at Warsaw University of Technology. The main purpose of the project is to create a controller to stabilize the vector sum of fields in cavities of one cryo-module in the experiment. The device can be also used as the simulator of the cavity and test bench for other devices. The synchronic, optical link project was made for the accelerator X-FEL laser TESLA, the LLRF control system experiment at DESY, Hamburg. The control and diagnostic data is transmitted up to 2.5Gbit/s through a plastic fiber in a distance up to a few hundred meters. The link is synchronized once after power up, and never resynchronized when data is transmitted with maximum speed. The one way link bit error rate is less then 10{sup -15}. The transceiver component written in VHDL that works in the dedicated Altera registered Stratix registered GX FPGA circuit. During the work in the PERG laboratory a 2,5Gbit/s serial link with the long vector parallel interface transceiver was created. Long-Data-Vector transceiver transmits 16bit vector each 8ns with 120ns latency. (orig.)

Synchronic, optical transmission data link integrated with FPGA circuits (for TESLA LLRF control system)

International Nuclear Information System (INIS)

Zielinski, J.S.

2006-05-01

The X-ray free-electron laser X-FEL that is being planned at the DESY research center in cooperation with European partners will produce high-intensity ultra-short X-ray flashes with the properties of laser light. This new light source, which can only be described in terms of superlatives, will open up a whole range of new possibilities for the natural sciences. It could also offer very promising opportunities for industrial users. SIMCON (SIMulator and CONtroller) is the project of the fast, low latency digital controller dedicated to the LLRF1 system in VUV FEL experiment It is being developed by the ELHEP2 group in the Institute of Electronic Systems at Warsaw University of Technology. The main purpose of the project is to create a controller to stabilize the vector sum of fields in cavities of one cryo-module in the experiment. The device can be also used as the simulator of the cavity and test bench for other devices. The synchronic, optical link project was made for the accelerator X-FEL laser TESLA, the LLRF control system experiment at DESY, Hamburg. The control and diagnostic data is transmitted up to 2.5Gbit/s through a plastic fiber in a distance up to a few hundred meters. The link is synchronized once after power up, and never resynchronized when data is transmitted with maximum speed. The one way link bit error rate is less then 10 -15 . The transceiver component written in VHDL that works in the dedicated Altera registered Stratix registered GX FPGA circuit. During the work in the PERG laboratory a 2,5Gbit/s serial link with the long vector parallel interface transceiver was created. Long-Data-Vector transceiver transmits 16bit vector each 8ns with 120ns latency. (orig.)

Dispersion of coupled mode-gap cavities

NARCIS (Netherlands)

Lian, Jin; Sokolov, Sergei; Yuce, E.; Combrie, S.; de Rossi, A.; Mosk, Allard

2015-01-01

The dispersion of a coupled resonator optical waveguide made of photonic crystal mode-gap cavities is pronouncedly asymmetric. This asymmetry cannot be explained by the standard tight binding model. We show that the fundamental cause of the asymmetric dispersion is the inherent dispersive cavity

Superconducting cavity driving with FPGA controller

International Nuclear Information System (INIS)

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

2006-01-01

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

Comparisons of hybrid radiosity-diffusion model and diffusion equation for bioluminescence tomography in cavity cancer detection

Science.gov (United States)

Chen, Xueli; Yang, Defu; Qu, Xiaochao; Hu, Hao; Liang, Jimin; Gao, Xinbo; Tian, Jie

2012-06-01

Bioluminescence tomography (BLT) has been successfully applied to the detection and therapeutic evaluation of solid cancers. However, the existing BLT reconstruction algorithms are not accurate enough for cavity cancer detection because of neglecting the void problem. Motivated by the ability of the hybrid radiosity-diffusion model (HRDM) in describing the light propagation in cavity organs, an HRDM-based BLT reconstruction algorithm was provided for the specific problem of cavity cancer detection. HRDM has been applied to optical tomography but is limited to simple and regular geometries because of the complexity in coupling the boundary between the scattering and void region. In the provided algorithm, HRDM was first applied to three-dimensional complicated and irregular geometries and then employed as the forward light transport model to describe the bioluminescent light propagation in tissues. Combining HRDM with the sparse reconstruction strategy, the cavity cancer cells labeled with bioluminescent probes can be more accurately reconstructed. Compared with the diffusion equation based reconstruction algorithm, the essentiality and superiority of the HRDM-based algorithm were demonstrated with simulation, phantom and animal studies. An in vivo gastric cancer-bearing nude mouse experiment was conducted, whose results revealed the ability and feasibility of the HRDM-based algorithm in the biomedical application of gastric cancer detection.

GCFR 1/20-scale PCRV central core cavity closure model test

International Nuclear Information System (INIS)

Robinson, G.C.; Dougan, J.R.

1981-06-01

Oak Ridge National Laboratory has been conducting structural response tests of the prestressed concrete reactor vessel (PCRV) closures for the 300-MW(e) gas-cooled fast reactor demonstration power plant. This report describes the third in a series of tests of small-scale closure plug models. The model represents a redesign of the central core cavity closure plug. The primary objective was to demonstrate structural performance and ultimate load capacity of the closure plug. Secondary objectives included obtaining data on crack development and propagation and on mode of failure of the composite structure

12 tesla test coil. Annual progress report

International Nuclear Information System (INIS)

1979-01-01

The Plasma Fusion Center at MIT has been charged with responsibility for the design, development, fabrication and test operation of a Niobium-3-Tin Superconducting Test Coil. Research is described on DOE's 12 tesla coil demonstration program in which several one-meter diameter superconducting test coils will be inserted and tested in DOE's High Field Test Facility at the Lawrence Livermore Laboratories. The work was initiated at the start of FY 79. FY 79 saw the completion of our Preliminary Design and the initiation of three (3) subcontracts: (1) Westinghouse review of the Preliminary Design, (II) Supercon, Inc. development of a tubular copper matrix, Nb 3 Sn Superconductor and (III) Airco optimization of the LCP-W Nb 3 Sn superconductor for 12T service. In addition, Airco was charged with the production of a 1000 foot length of model 15,000A conductor. Coil winding exercises were initiated at the Everson Electric Company

Using dynamic N-mixture models to test cavity limitation on northern flying squirrel demographic parameters using experimental nest box supplementation.

Science.gov (United States)

Priol, Pauline; Mazerolle, Marc J; Imbeau, Louis; Drapeau, Pierre; Trudeau, Caroline; Ramière, Jessica

2014-06-01

Dynamic N-mixture models have been recently developed to estimate demographic parameters of unmarked individuals while accounting for imperfect detection. We propose an application of the Dail and Madsen (2011: Biometrics, 67, 577-587) dynamic N-mixture model in a manipulative experiment using a before-after control-impact design (BACI). Specifically, we tested the hypothesis of cavity limitation of a cavity specialist species, the northern flying squirrel, using nest box supplementation on half of 56 trapping sites. Our main purpose was to evaluate the impact of an increase in cavity availability on flying squirrel population dynamics in deciduous stands in northwestern Québec with the dynamic N-mixture model. We compared abundance estimates from this recent approach with those from classic capture-mark-recapture models and generalized linear models. We compared apparent survival estimates with those from Cormack-Jolly-Seber (CJS) models. Average recruitment rate was 6 individuals per site after 4 years. Nevertheless, we found no effect of cavity supplementation on apparent survival and recruitment rates of flying squirrels. Contrary to our expectations, initial abundance was not affected by conifer basal area (food availability) and was negatively affected by snag basal area (cavity availability). Northern flying squirrel population dynamics are not influenced by cavity availability at our deciduous sites. Consequently, we suggest that this species should not be considered an indicator of old forest attributes in our study area, especially in view of apparent wide population fluctuations across years. Abundance estimates from N-mixture models were similar to those from capture-mark-recapture models, although the latter had greater precision. Generalized linear mixed models produced lower abundance estimates, but revealed the same relationship between abundance and snag basal area. Apparent survival estimates from N-mixture models were higher and less precise

Multipacting studies in elliptic SRF cavities

Science.gov (United States)

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

2017-09-01

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

Impact of Lorentz forces on a Spoke cavity with β 0.15 and on a Spiral-2 cavity with β 0.12

International Nuclear Information System (INIS)

Gassot, H.

2007-01-01

Mono-spoke superconducting cavities have been proposed for the acceleration of radioactive ion beams. The interaction of the electromagnetic field with the surface electrical current generates Lorentz forces that operate on the intern wall of the cavity, the distribution of these forces is highly non-linear and varying. The stability of a superconducting cavity is directly linked to the frequency variation due to Lorentz forces and as a consequence the optimized design of a cavity must take into account these forces. In order to optimize the design of a cavity, 3 complementary software have been developed: Catia, a computer-aided-design software, Soprano for electromagnetic modeling and Cast3m for mechanical modeling. Preliminary results show a good agreement between predicted values and experimental data. (A.C.)

High power test of RF window and coaxial line in vacuum

International Nuclear Information System (INIS)

Sun, D.; Champion, M.; Gormley, M.; Kerns, Q.; Koepke, K.; Moretti, A.

1993-01-01

Primary rf input couplers for the superconducting accelerating cavities of the TESLA electron linear accelerator test to be performed at DESY, Hamburg, Germany are under development at both DESY and Fermilab. The input couplers consist of a WR650 waveguide to coaxial line transition with an integral ceramic window, a coaxial connection to the superconducting accelerating cavity with a second ceramic window located at the liquid nitrogen heat intercept location, and bellows on both sides of the cold window to allow for cavity motion during cooldown, coupling adjustments and easier assembly. To permit in situ high peak power processing of the TESLA superconducting accelerating cavities, the input couplers are designed to transmit nominally 1 ms long, 2 MW peak, 1.3 GHz rf pulses from the WR650 waveguide at room temperature to the cavities at 1.8 K. The coaxial part of the Fermilab TESLA input coupler design has been tested up to 1.7 MW using the prototype 805 MHz rf source located at the A0 service building of the Tevatron. The rf source, the testing system and the test results are described

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.

Tesla-VUPJT instruments suitable for application in water management

International Nuclear Information System (INIS)

Novakova, O.; Broj, K.; Fronka, O.; Kula, J.; Slezak, V.

1987-01-01

A comparison is made of new instruments by Tesla, Czechoslovakia, viz. the NA 6201 for low alpha and beta counting and the NRR 610 alpha-beta automatic gauge, with similar foreign made instruments. The factors are discussed which affect the overall detection efficiency and the background level. (B.S.). 4 tabs

Shunt impedance of spiral loaded resonant rf cavities

International Nuclear Information System (INIS)

Peebles, P.Z. Jr.; Parvarandeh, M.

1975-01-01

Based upon a treatment of the spiral loaded resonant radio frequency cavity as a shorted quarter-wave transmission line, a model for shunt impedance is developed. The model is applicable to loosely wound spirals in large diameter containers. Theoretical shunt impedance is given for spirals wound from tubing of circular or rectangular cross section. The former produces higher shunt impedance. Measurements made at Oak Ridge National Laboratory on 17 copper cavities are described which support the theoretical results. Theoretical results are also compared to data from twenty-three additional cavities measured at Los Alamos Scientific Laboratory. It is shown that the theoretical function forms a useful means of interpreting the quality of constructed cavities. (author)

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...

Design of 118 MHz twelfth harmonic cavity of APS PAR

International Nuclear Information System (INIS)

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

1992-01-01

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

Four-Phase Dendritic Model for the Prediction of Macrosegregation, Shrinkage Cavity, and Porosity in a 55-Ton Ingot

Science.gov (United States)

Ge, Honghao; Ren, Fengli; Li, Jun; Han, Xiujun; Xia, Mingxu; Li, Jianguo

2017-03-01

A four-phase dendritic model was developed to predict the macrosegregation, shrinkage cavity, and porosity during solidification. In this four-phase dendritic model, some important factors, including dendritic structure for equiaxed crystals, melt convection, crystals sedimentation, nucleation, growth, and shrinkage of solidified phases, were taken into consideration. Furthermore, in this four-phase dendritic model, a modified shrinkage criterion was established to predict shrinkage porosity (microporosity) of a 55-ton industrial Fe-3.3 wt pct C ingot. The predicted macrosegregation pattern and shrinkage cavity shape are in a good agreement with experimental results. The shrinkage cavity has a significant effect on the formation of positive segregation in hot top region, which generally forms during the last stage of ingot casting. The dendritic equiaxed grains also play an important role on the formation of A-segregation. A three-dimensional laminar structure of A-segregation in industrial ingot was, for the first time, predicted by using a 3D case simulation.

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%.

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%.

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%.

Comparison of Pelvic Phased-Array versus Endorectal Coil Magnetic Resonance Imaging at 3 Tesla for Local Staging of Prostate Cancer

OpenAIRE

Kim, Bum Soo; Kim, Tae-Hwan; Kwon, Tae Gyun; Yoo, Eun Sang

2012-01-01

Purpose Several studies have demonstrated the superiority of endorectal coil magnetic resonance imaging (MRI) over pelvic phased-array coil MRI at 1.5 Tesla for local staging of prostate cancer. However, few have studied which evaluation is more accurate at 3 Tesla MRI. In this study, we compared the accuracy of local staging of prostate cancer using pelvic phased-array coil or endorectal coil MRI at 3 Tesla. Materials and Methods Between January 2005 and May 2010, 151 patients underwent radi...

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)

Temperature and EUV Intensity in a Coronal Prominence Cavity and Streamer

Science.gov (United States)

Kucera, T. A.; Gibson, S.E.; Schmit, D. J.; Landi, E.; Tripathi, D.

2012-01-01

We analyze the temperature and EUV line emission of a coronal cavity and surrounding streamer in terms of a morphological forward model. We use a series of iron line ratios observed with the Hinode Extreme-ultraviolet Imaging Spectrograph (EIS) on 2007 Aug. 9 to constrain temperature as a function of altitude in a morphological forward model of the streamer and cavity. We also compare model prediction of the EIS EUV line intensities and polarized brightness (pB) data from the Mauna Loa Solar Observatory (MLSO) MK4. This work builds on earlier analysis using the same model to determine geometry of and density in the same cavity and streamer. The fit to the data with altitude dependent temperature profiles indicates that both the streamer and cavity have temperatures in the range 1.4-1.7 MK. However, the cavity exhibits substantial substructure such that the altitude dependent temperature profile is not sufficient to completely model conditions in the cavity. Coronal prominence cavities are structured by magnetism so clues to this structure are to be found in their plasma properties. These temperature substructures are likely related to structures in the cavity magnetic field. Furthermore, we find that the model overestimates the line intensities by a factor of 4-10, while overestimating pB data by no more than a factor of 1.4. One possible explanation for this is that there may be a significant amount of material at temperatures outside of the range log T(K) approximately equals 5.8 - 6.7 in both the cavity and the streamer.

Contribution to study and realization of 20-Tesla superconducting magnet

International Nuclear Information System (INIS)

Marty, J.

1981-11-01

This work is mainly concerned with 20 Tesla induction production study. This magnetic induction should be produced by associating a series of coils using high critical field commercial: superconductors to the 10 Tesla magnet (diameter: 300; let's call it 10-300 magnet). The operation temperature lowering from 4,2 0 K to 1,8 0 K should effectively lead to much higher inductions (with equal effective diameter) than the greatest performances nowadays realized at 4,2 0 K temperature. To this performance augmentation is associated a more important energy density augmentation. This leads to the necessity of the knowledge of the superconducting material physical properties. They are studied in this report. Following, different methodes of magnet calculations are described: problems related to mechanical constraints, protection and stability must be known. Finally, some coils of the 10-300 magnet are presented together with their realization [fr

Trimming algorithm of frequency modulation for CIAE-230 MeV proton superconducting synchrocyclotron model cavity

Energy Technology Data Exchange (ETDEWEB)

Li, Pengzhan, E-mail: lipengzhan@ciae.ac.cn; Zhang, Tianjue; Ji, Bin; Hou, Shigang; Guo, Juanjuan; Yin, Meng; Xing, Jiansheng; Lv, Yinlong; Guan, Fengping; Lin, Jun

2017-01-21

A new project, the 230 MeV proton superconducting synchrocyclotron for cancer therapy, was proposed at CIAE in 2013. A model cavity is designed to verify the frequency modulation trimming algorithm featuring a half-wave structure and eight sets of rotating blades for 1 kHz frequency modulation. Based on the electromagnetic (EM) field distribution analysis of the model cavity, the variable capacitor works as a function of time and the frequency can be written in Maclaurin series. Curve fitting is applied for theoretical frequency and original simulation frequency. The second-order fitting excels at the approximation given its minimum variance. Constant equivalent inductance is considered as an important condition in the calculation. The equivalent parameters of theoretical frequency can be achieved through this conversion. Then the trimming formula for rotor blade outer radius is found by discretization in time domain. Simulation verification has been performed and the results show that the calculation radius with minus 0.012 m yields an acceptable result. The trimming amendment in the time range of 0.328–0.4 ms helps to reduce the frequency error to 0.69% in Simulation C with an increment of 0.075 mm/0.001 ms, which is half of the error in Simulation A (constant radius in 0.328–0.4 ms). The verification confirms the feasibility of the trimming algorithm for synchrocyclotron frequency modulation. - Highlights: • A model cavity is designed to verify the trimming algorithm of frequency modulation. • The RF frequency is expressed by fitting approximation and Maclaurin series. • The variable capacitor of the cavity works as a function of time. • The trimming formula for blade radius is found by discretization in time domain. • The amendment solution helps to reduce the frequency error.

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.

Modeling the interaction of a heavily beam loaded SRF cavity with its low-level RF feedback loops

Science.gov (United States)

Liu, Zong-Kai; Wang, Chaoen; Chang, Lung-Hai; Yeh, Meng-Shu; Chang, Fu-Yu; Chang, Mei-Hsia; Chang, Shian-Wen; Chen, Ling-Jhen; Chung, Fu-Tsai; Lin, Ming-Chyuan; Lo, Chih-Hung; Yu, Tsung-Chi

2018-06-01

A superconducting radio frequency (SRF) cavity provides superior stability to power high intensity light sources and can suppress coupled-bunch instabilities due to its smaller impedance for higher order modes. Because of these features, SRF cavities are commonly used for modern light sources, such as the TLS, CLS, DLS, SSRF, PLS-II, TPS, and NSLS-II, with an aggressive approach to operate the light sources at high beam currents. However, operating a SRF cavity at high beam currents may result with unacceptable stability problems of the low level RF (LLRF) system, due to drifts of the cavity resonant frequency caused by unexpected perturbations from the environment. As the feedback loop gets out of control, the cavity voltage may start to oscillate with a current-dependent characteristic frequency. Such situations can cause beam abort due to the activation of the interlock protection system, i.e. false alarm of quench detection. This malfunction of the light source reduces the reliability of SRF operation. Understanding this unstable mechanism to prevent its appearance becomes a primary task in the pursuit of highly reliable SRF operation. In this paper, a Pedersen model, including the response of the LLRF system, was used to simulate the beam-cavity interaction of a SRF cavity under heavy beam loading. Causes for the onset of instability at high beam current will be discussed as well as remedies to assure the design of a stable LLRF system.

Conventional 20-TeV, 10-Tesla, p/sup +-/ colliders

International Nuclear Information System (INIS)

Diebold, R.; Ankenbrandt, C.; Collins, T.

1982-01-01

The performance of various 20-TeV colliders is discussed assuming 10-Tesla bending magnets. For bunched beams, the luminosity for anti pp collisions will be approximately x 10 31 cm - 2 sec - 1 where is the average number of interactions per bunch collision desired by the experimenters; for pp collisions this becomes x 10 32 cm - 2 sec - 1 . Values of up to 25 can be accommodated in a straightforward manner. Continuous beam pp collisions may yield a luminosity of 10 33 to 10 34 cm - 2 sec - 1 if the large amount of energy in the intense beams can be handled. Assuming that adequate and reliable 10-Tesla magnets can be built without unforeseen difficulties, the construction cost of such a collider, together with its new laboratory in the desert, would cost 2 to 3 billion dollars (FY-82 dollars) using present-day, conventional techniques. Although such a machine appears straightforward to build, considerable R and D will be required in order to optimize the design and bring down costs

Evaluation of bond strength of silorane and methacrylate based restorative systems to dentin using different cavity models

Directory of Open Access Journals (Sweden)

Stephano Zerlottini Isaac

2013-09-01

Full Text Available OBJECTIVE: The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS to dentin of two different restorative systems: silorane-based (P90, and methacrylate-based (P60, using two cavity models. MATERIAL AND METHODS: Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5 were prepared in 20 teeth, which were divided into two groups (n=10 restored with P60 and P90, bulk-filled after dentin treatment according to manufacturer's instructions. Flat buccal dentin surfaces were prepared in the 20 remaining teeth (C-factor=0.2 and restored with resin blocks measuring 4x3x3 mm using the two restorative systems (n=10. The teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to µTBS testing, using a universal testing machine (EMIC at speed of 0.5 mm/min. Fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. Data were analyzed using ANOVA and Tukey Kramer tests. RESULTS: For flat surfaces, P60 obtained higher bond strength values compared with P90. However, for Class I cavities, P60 showed significant reduction in bond strength (p0.05, or between Class I Cavity and Flat Surface group, considering P90 restorative system (p>0.05. Regarding fracture pattern, there was no statistical difference among groups (p=0.0713 and 56.3% of the fractures were adhesive. CONCLUSION: It was concluded that methacrylate-based composite µTBS was influenced by cavity models, and the use of silorane-based composite led to similar bond strength values compared to the methacrylate-based composite in cavities with high C-factor.

Complex envelope control of pulsed accelerating fields in superconducting cavities

CERN Document Server

Czarski, T

2010-01-01

A digital control system for superconducting cavities of a linear accelerator is presented in this work. FPGA (Field Programmable Gate Arrays) based controller, managed by MATLAB, was developed to investigate a novel firmware implementation. The LLRF - Low Level Radio Frequency system for FLASH project in DESY is introduced. Essential modeling of a cavity resonator with signal and power analysis is considered as a key approach to the control methods. An electrical model is represented by the non-stationary state space equation for the complex envelope of the cavity voltage driven by the current generator and the beam loading. The electromechanical model of the superconducting cavity resonator including the Lorentz force detuning has been developed for a simulation purpose. The digital signal processing is proposed for the field vector detection. The field vector sum control is considered for multiple cavities driven by one klystron. An algebraic, complex domain model is proposed for the system analysis. The c...

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

An 8-GW long-pulse generator based on Tesla transformer and pulse forming network.

Science.gov (United States)

Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin

2014-06-01

A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

An 8-GW long-pulse generator based on Tesla transformer and pulse forming network

Energy Technology Data Exchange (ETDEWEB)

Su, Jiancang; Zhang, Xibo; Li, Rui; Zhao, Liang, E-mail: zhaoliang0526@163.com; Sun, Xu; Wang, Limin; Zeng, Bo; Cheng, Jie; Wang, Ying; Peng, Jianchang; Song, Xiaoxin [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an, Shaanxi 710024 (China)

2014-06-15

A long-pulse generator TPG700L based on a Tesla transformer and a series pulse forming network (PFN) is constructed to generate intense electron beams for the purpose of high power microwave (HPM) generation. The TPG700L mainly consists of a 12-stage PFN, a built-in Tesla transformer in a pulse forming line, a three-electrode gas switch, a transmission line with a trigger, and a load. The Tesla transformer and the compact PFN are the key technologies for the development of the TPG700L. This generator can output electrical pulses with a width as long as 200 ns at a level of 8 GW and a repetition rate of 50 Hz. When used to drive a relative backward wave oscillator for HPM generation, the electrical pulse width is about 100 ns on a voltage level of 520 kV. Factors affecting the pulse waveform of the TPG700L are also discussed. At present, the TPG700L performs well for long-pulse HPM generation in our laboratory.

Toroidal 12 cavity klystron : a novel approach

International Nuclear Information System (INIS)

Hazarika, A.B.R.

2013-01-01

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

Excerpts from Prodigal Genius: The Life of Nikola Tesla

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 3. Excerpts from Prodigal Genius: The Life of Nikola Tesla. John J O Neill. Classics Volume 12 Issue 3 March 2007 pp 91-96. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/012/03/0091-0096 ...

Minimum wakefield achievable by waveguide damped cavity

International Nuclear Information System (INIS)

Lin, X.E.; Kroll, N.M.

1995-01-01

The authors use an equivalent circuit to model a waveguide damped cavity. Both exponentially damped and persistent (decay t -3/2 ) components of the wakefield are derived from this model. The result shows that for a cavity with resonant frequency a fixed interval above waveguide cutoff, the persistent wakefield amplitude is inversely proportional to the external Q value of the damped mode. The competition of the two terms results in an optimal Q value, which gives a minimum wakefield as a function of the distance behind the source particle. The minimum wakefield increases when the resonant frequency approaches the waveguide cutoff. The results agree very well with computer simulation on a real cavity-waveguide system

Application of the three-component bidirectional reflectance distribution function model to Monte Carlo calculation of spectral effective emissivities of nonisothermal blackbody cavities.

Science.gov (United States)

Prokhorov, Alexander; Prokhorova, Nina I

2012-11-20

We applied the bidirectional reflectance distribution function (BRDF) model consisting of diffuse, quasi-specular, and glossy components to the Monte Carlo modeling of spectral effective emissivities for nonisothermal cavities. A method for extension of a monochromatic three-component (3C) BRDF model to a continuous spectral range is proposed. The initial data for this method are the BRDFs measured in the plane of incidence at a single wavelength and several incidence angles and directional-hemispherical reflectance measured at one incidence angle within a finite spectral range. We proposed the Monte Carlo algorithm for calculation of spectral effective emissivities for nonisothermal cavities whose internal surface is described by the wavelength-dependent 3C BRDF model. The results obtained for a cylindroconical nonisothermal cavity are discussed and compared with results obtained using the conventional specular-diffuse model.

Natural radioactivity of coal and fly ash at the Nikola Tesla B TPP

Directory of Open Access Journals (Sweden)

Kisić Dragica M.

2013-01-01

Full Text Available Serbian thermal power plants (TPPs produce siliceous fly ash from lignite in the quantity of approximately 6 million tons per year. The potential market for the use of fly ash is operational, but for the time being, only used by cement producers. Fly ash radioactivity could be one of the major points of concern when larger use of fly ash is planned, particularly in the Serbian construction industry. Radioactivity measurements have been conducted regularly for decades. This paper presents the results of a ten-year fly ash radioactivity measurements at the Nikola Tesla B TPP located in Obrenovac. In addition, the paper compares the natural radionuclides coal content data combusted by the Nikola Tesla B TPP boilers coming from the Kolubara Basin and ash created during coal combustion. Fly ash created in the Nikola Tesla TPPs boilers is characterised by the increased concentration of the natural radionuclides content compared to coal. This is the so-called technologically enhanced natural radioactivity (Technologically Enhanced Occurring Radioactive Material - TENORM of industrial waste, whereas the average specific activities: 232Th in coal amount to 25.2 Bq/kg, and in fly ash and coal 84.2 Bq/kg and 238U 38.3 Bq/kg, respectively. Following the obtained natural radionuclides content results it may be concluded that the Nikola Tesla B TPP ash may be disposed into the environment. Ash may be used also in the construction industry (civil engineering. In building construction applications, ash share as the additive to other building materials depends from its physical and chemical characteristics, as well as from the radionuclides activity: 266Ra, 232Th and 40K. Unlike the thermal power plants regularly (once a year testing the specific natural radionuclides activity in the combusted coal and boiler fly ash, Electric Power Industry of Serbia has not performed large-scale investigations of the natural radionuclides content in coal within the Kolubara

4 Tesla Whole Body MRI MRSI System for Investigation of Neurodegenerative Diseases

National Research Council Canada - National Science Library

Weiner, Michael W

2004-01-01

The overall long-term goal of imaging research to be performed with this 4 Tesla Siemens/Bruker MRI system is the development of improved diagnostic methods for accurate detection of neurodegenerative...

Cantilever piezoelectric energy harvester with multiple cavities

International Nuclear Information System (INIS)

S Srinivasulu Raju; M Umapathy; G Uma

2015-01-01

Energy harvesting employing piezoelectric materials in mechanical structures such as cantilever beams, plates, diaphragms, etc, has been an emerging area of research in recent years. The research in this area is also focused on structural tailoring to improve the harvested power from the energy harvesters. Towards this aim, this paper presents a method for improving the harvested power from a cantilever piezoelectric energy harvester by introducing multiple rectangular cavities. A generalized model for a piezoelectric energy harvester with multiple rectangular cavities at a single section and two sections is developed. A method is suggested to optimize the thickness of the cavities and the number of cavities required to generate a higher output voltage for a given cantilever beam structure. The performance of the optimized energy harvesters is evaluated analytically and through experimentation. The simulation and experimental results show that the performance of the energy harvester can be increased with multiple cavities compared to the harvester with a single cavity. (paper)

Diffusion tensor imaging of the normal prostate at 3 Tesla

International Nuclear Information System (INIS)

Guerses, Bengi; Kabakci, Neslihan; Kovanlikaya, Arzu; Firat, Zeynep; Bayram, Ali; Kovanlikaya, Ilhami; Ulud, Aziz M.

2008-01-01

The aim of this study was to assess the feasibility of diffusion tensor imaging (DTI) of the prostate and to determine normative fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of healthy prostate with a 3-Tesla magnetic resonance imaging (MRI) system. Thirty volunteers with a mean age of 28 (25-35) years were scanned with a 3-Tesla MRI (Intera Achieva; Philips, The Netherlands) system using a six-channel phased array coil. Initially, T2-weighted turbo spin-echo (TSE) axial images of the prostate were obtained. In two subjects, a millimetric hypointense signal change was detected in the peripheral zones on T2-weighted TSE images. These two subjects were excluded from the study. DTI with single-shot echo-planar imaging (ssEPI) was performed in the remaining 28 subjects. ADC and FA values were measured using the manufacturer supplied software by positioning 9-pixel ROIs on each zone. Differences between parameters of the central and peripheral zones were assessed. Mean ADC value of the central (1.220 ± 0.271 x 10 -3 mm 2 /s) was found to be significantly lower when compared with the peripheral gland (1.610 ± 0.347 x 10 -3 mm 2 /s) (P < 0.01). Mean FA of the central gland was significantly higher (0.26), compared with the peripheral gland (0.16) (P < 0.01). This study shows the feasibility of prostate DTI with a 3-Tesla MR system and the normative FA and ADC values of peripheral and central zones of the normal prostate. The results are compatible with the microstructural organization of the gland. (orig.)

Cooling tests of the cryomodules at superconducting RF test facility (STF)

International Nuclear Information System (INIS)

Ohuchi, Norihito; Nakai, Hirotaka; Kojima, Yuuji

2009-01-01

KEK has been constructing the Superconducting RF Test Facility (STF) with aiming at a center of the ILC-R and D in Asia from 2005. In this project, KEK targets manufacturing and operational experiences of the RF cavity and cryomodule toward the ILC, and two cryomodules have been developed. These cryomodules are 6 meter long and have 4 nine-cell cavities in each cryostat. The designs of the cryomodules are based on the TESLA Type-3 (TTF-3) at DESY, however, each cryostat has the different type of cavities, TESLA-like type and Low-Loss type. The tests of the cryomodules were performed in two steps. In the first test, measurements of the cryogenic performances of these cryomodules were the main objective. One nine-cell cavity was assembled in each cryomodule and cool-down of the two cryomodules was performed, individually. In the second test, the four TESLA-like cavities were assembled in the cryomodule as complete integration. Cool-down of the cryomodule to 2 K was successfully completed, and thermal performances of the cryomodule and cooling capacity of the cryogenics system were studied in detail. In this paper, we will report the design of the cryomodules and the thermal performances at these cold tests. (author)

Simulation of beam instabilities in a superconducting linear collider

International Nuclear Information System (INIS)

Aune, B.; Mosnier, A.; Napoly, O.

1992-01-01

Some results on the short range and long range wakefields effects due to the SC cavities on a beam emerging from a TESLA linac are presented. First, the intrabunch energy spread is estimated after the usual linac phase optimisation. Next, multibunch transverse instability is studied with several schemes of constant beta FODO focusing. In both cases, the parameters of a realistic 1.3 Ghz TESLA cavity and the parameters of the two machines 'Top-Factory' and '1/2 TESLA' are considered. It is concluded that the longitudinal wake effect is not a problem in both machines and that a rather weak focusing scheme is sufficient to keep the emittance at the 10 -6 m rad design value. (author) 6 refs.; 9 figs.; 3 tabs

Inhibited emission of electromagnetic modes confined in subwavelength cavities

International Nuclear Information System (INIS)

Le Thomas, N.; Houdre, R.

2011-01-01

We experimentally demonstrate the active inhibition of subwavelength confined cavity modes emission and quality factor enhancement by controlling the cavity optical surrounding. The intrinsic radiation angular spectrum of modes confined in planar photonics crystal cavities as well as its modifications depending on the environment are inferred via a transfer matrix modeling and k-space imaging.

CFD analysis of a scramjet combustor with cavity based flame holders

Science.gov (United States)

Kummitha, Obula Reddy; Pandey, Krishna Murari; Gupta, Rajat

2018-03-01

Numerical analysis of a scramjet combustor with different cavity flame holders has been carried out using ANSYS 16 - FLUENT tool. In this research article the internal fluid flow behaviour of the scramjet combustor with different cavity based flame holders have been discussed in detail. Two dimensional Reynolds-Averaged Navier-Stokes governing(RANS) equations and shear stress turbulence (SST) k - ω model along with finite rate/eddy dissipation chemistry turbulence have been considered for modelling chemical reacting flows. Due to the advantage of less computational time, global one step reaction mechanism has been used for combustion modelling of hydrogen and air. The performance of the scramjet combustor with two different cavities namely spherical and step cavity has been compared with the standard DLR scramjet. From the comparison of numerical results, it is found that the development of recirculation regions and additional shock waves from the edge of cavity flame holder is increased. And also it is observed that with the cavity flame holder the residence time of air in the scramjet combustor is also increased and achieved stabilized combustion. From this research analysis, it has been found that the mixing and combustion efficiency of scramjet combustor with step cavity design is optimum as compared to other models.

Multicontrast-weighted magnetic resonance imaging of atherosclerotic plaques at 3.0 and 1.5 Tesla: ex-vivo comparison with histopathologic correlation

International Nuclear Information System (INIS)

Koops, Andreas; Ittrich, Harald; Priest, Andrew; Stork, Alexander; Adam, Gerhard; Weber, Christoph; Petri, Susan; Lockemann, Ute

2007-01-01

The purpose was to analyze magnetic resonance (MR) plaque imaging at 3.0 Tesla and 1.5 Tesla in correlation with histopathology. MR imaging (MRI) of the abdominal aorta and femoral artery was performed on seven corpses using T1-weighted, T2-weighted, and PD-weighted sequences at 3.0 and 1.5 Tesla. Cross-sectional images at the branching of the inferior mesenteric artery and the profunda femoris were rated with respect to image quality. Corresponding cross sections of the imaged vessels were obtained at autopsy. The atherosclerotic plaques in the histological slides and MR images were classified according to the American Heart Association (AHA) and analyzed for differences. MRI at 3.0 Tesla offered superior depiction of arterial wall composition in all contrast weightings, rated best for T2-weighted images. Comparing for field strength, the highest differences were observed in T1-weighted and T2-weighted techniques (both P≤0.001), with still significant differences in PD-weighted sequence (P≤0.005). The majority of plaques were histologically classified as calcified plaques. In up to 21% of the cases, MRI at both field strengths detected signal loss characteristic of calcification although calcified plaque was absent in histology. MRI at 3.0 Tesla offers superior plaque imaging quality compared with 1.5 Tesla, but further work is necessary to determine whether this translates in superior diagnostic accuracy. (orig.)

Dynamic contrast-enhanced breast MRI at 7 Tesla utilizing a single-loop coil: a feasibility trial.

Science.gov (United States)

Umutlu, Lale; Maderwald, Stefan; Kraff, Oliver; Theysohn, Jens M; Kuemmel, Sherko; Hauth, Elke A; Forsting, Michael; Antoch, Gerald; Ladd, Mark E; Quick, Harald H; Lauenstein, Thomas C

2010-08-01

The aim of this study was to assess the feasibility of dynamic contrast-enhanced ultra-high-field breast imaging at 7 Tesla. A total of 15 subjects, including 5 patients with histologically proven breast cancer, were examined on a 7 Tesla whole-body magnetic resonance imaging system using a unilateral linearly polarized single-loop coil. Subjects were placed in prone position on a biopsy support system, with the coil placed directly below the region of interest. The examination protocol included the following sequences: 1) T2-weighted turbo spin echo sequence; 2) six dynamic T1-weighted spoiled gradient-echo sequences; and 3) subtraction imaging. Contrast-enhanced T1-weighted imaging at 7 Tesla could be obtained at high spatial resolution with short acquisition times, providing good image accuracy and a conclusively good delineation of small anatomical and pathological structures. T2-weighted imaging could be obtained with high spatial resolution at adequate acquisition times. Because of coil limitations, four high-field magnetic resonance examinations showed decreased diagnostic value. This first scientific approach of dynamic contrast-enhanced breast magnetic resonance imaging at 7 Tesla demonstrates the complexity of ultra-high-field breast magnetic resonance imaging and countenances the implementation of further advanced bilateral coil concepts to circumvent current limitations from the coil and ultra-high-field magnetic strength. 2010 AUR. Published by Elsevier Inc. All rights reserved.

TEMPERATURE AND EXTREME-ULTRAVIOLET INTENSITY IN A CORONAL PROMINENCE CAVITY AND STREAMER

Energy Technology Data Exchange (ETDEWEB)

Kucera, T. A. [NASA/GSFC, Code 671, Greenbelt, MD 20771 (United States); Gibson, S. E.; Schmit, D. J. [HAO/NCAR, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Landi, E. [Department of Atmospheric, Oceanic and Space Science, Space Research Building, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143 (United States); Tripathi, D. [Inter-University Centre for Astronomy and Astrophysics, Post Bag-4, Ganeshkhind, Pune University Campus, Pune 411 007 (India)

2012-09-20

We analyze the temperature and EUV line emission of a coronal cavity and surrounding streamer in terms of a morphological forward model. We use a series of iron line ratios observed with the Hinode Extreme-ultraviolet Imaging Spectrograph (EIS) on 2007 August 9 to constrain temperature as a function of altitude in a morphological forward model of the streamer and cavity. We also compare model predictions to the EIS EUV line intensities and polarized brightness (pB) data from the Mauna Loa Solar Observatory (MLSO) Mark 4 K-coronameter. This work builds on earlier analysis using the same model to determine geometry of and density in the same cavity and streamer. The fit to the data with altitude-dependent temperature profiles indicates that both the streamer and cavity have temperatures in the range 1.4-1.7 MK. However, the cavity exhibits substantial substructure such that the altitude-dependent temperature profile is not sufficient to completely model conditions in the cavity. Coronal prominence cavities are structured by magnetism so clues to this structure are to be found in their plasma properties. These temperature substructures are likely related to structures in the cavity magnetic field. Furthermore, we find that the model overestimates the EUV line intensities by a factor of 4-10, without overestimating pB. We discuss this difference in terms of filling factors and uncertainties in density diagnostics and elemental abundances.

Hippocampal disconnection in early Alzheimer's disease: a 7 tesla MRI study

NARCIS (Netherlands)

Wisse, L.E.; Reijmer, Y.D.; Telgte, A. ter; Kuijf, H.J.; Leemans, A.; Luijten, P.R.; Koek, H.L.; Geerlings, M.I.; Biessels, G.J.

2015-01-01

BACKGROUND: In patients with Alzheimer's disease (AD), atrophy of the entorhinal cortex (ERC) and hippocampal formation may induce degeneration of connecting white matter tracts. OBJECTIVE: We examined the association of hippocampal subfield and ERC atrophy at 7 tesla MRI with fornix and

Cortical Cerebral Microinfarcts on 3 Tesla MRI in Patients with Vascular Cognitive Impairment.

Science.gov (United States)

Ferro, Doeschka A; van Veluw, Susanne J; Koek, Huiberdina L; Exalto, Lieza G; Biessels, Geert Jan

2017-01-01

Cerebral microinfarcts (CMIs) are small ischemic lesions that are a common neuropathological finding in patients with stroke or dementia. CMIs in the cortex can now be detected in vivo on 3 Tesla MRI. To determine the occurrence of CMIs and associated clinical features in patients with possible vascular cognitive impairment (VCI). 182 memory-clinic patients (mean age 71.4±10.6, 55% male) with vascular injury on brain MRI (i.e., possible VCI) underwent a standardized work-up including 3 Tesla MRI and cognitive assessment. A control group consisted of 70 cognitively normal subjects (mean age 70.6±4.7, 60% male). Cortical CMIs and other neuroimaging markers of vascular brain injury were rated according to established criteria. Occurrence of CMIs was higher (20%) in patients compared to controls (10%). Among patients, the presence of CMIs was associated with male sex, history of stroke, infarcts, and white matter hyperintensities. CMI presence was also associated with a diagnosis of vascular dementia and reduced performance in multiple cognitive domains. CMIs on 3 Tesla MRI are common in patients with possible VCI and co-occur with imaging markers of small and large vessel disease, likely reflecting a heterogeneous etiology. CMIs are associated with worse cognitive performance, independent of other markers of vascular brain injury.

A semi-automated algorithm for hypothalamus volumetry in 3 Tesla magnetic resonance images.

Science.gov (United States)

Wolff, Julia; Schindler, Stephanie; Lucas, Christian; Binninger, Anne-Sophie; Weinrich, Luise; Schreiber, Jan; Hegerl, Ulrich; Möller, Harald E; Leitzke, Marco; Geyer, Stefan; Schönknecht, Peter

2018-07-30

The hypothalamus, a small diencephalic gray matter structure, is part of the limbic system. Volumetric changes of this structure occur in psychiatric diseases, therefore there is increasing interest in precise volumetry. Based on our detailed volumetry algorithm for 7 Tesla magnetic resonance imaging (MRI), we developed a method for 3 Tesla MRI, adopting anatomical landmarks and work in triplanar view. We overlaid T1-weighted MR images with gray matter-tissue probability maps to combine anatomical information with tissue class segmentation. Then, we outlined regions of interest (ROIs) that covered potential hypothalamus voxels. Within these ROIs, seed growing technique helped define the hypothalamic volume using gray matter probabilities from the tissue probability maps. This yielded a semi-automated method with short processing times of 20-40 min per hypothalamus. In the MRIs of ten subjects, reliabilities were determined as intraclass correlations (ICC) and volume overlaps in percent. Three raters achieved very good intra-rater reliabilities (ICC 0.82-0.97) and good inter-rater reliabilities (ICC 0.78 and 0.82). Overlaps of intra- and inter-rater runs were very good (≥ 89.7%). We present a fast, semi-automated method for in vivo hypothalamus volumetry in 3 Tesla MRI. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of MRI Issues at 3 Tesla for a New Metallic Tissue Marker

Science.gov (United States)

Cronenweth, Charlotte M.; Shellock, Frank G.

2015-01-01

Purpose. To assess the MRI issues at 3 Tesla for a metallic tissue marker used to localize removal areas of tissue abnormalities. Materials and Methods. A newly designed, metallic tissue marker (Achieve Marker, CareFusion, Vernon Hills, IL) used to mark biopsy sites, particularly in breasts, was assessed for MRI issues which included standardized tests to determine magnetic field interactions (i.e., translational attraction and torque), MRI-related heating, and artifacts at 3 Tesla. Temperature changes were determined for the marker using a gelled-saline-filled phantom. MRI was performed at a relatively high specific absorption rate (whole body averaged SAR, 2.9-W/kg). MRI artifacts were evaluated using T1-weighted, spin echo and gradient echo pulse sequences. Results. The marker displayed minimal magnetic field interactions (2-degree deflection angle and no torque). MRI-related heating was only 0.1°C above background heating (i.e., the heating without the tissue marker present). Artifacts seen as localized signal loss were relatively small in relation to the size and shape of the marker. Conclusions. Based on the findings, the new metallic tissue marker is acceptable or “MR Conditional” (using current labeling terminology) for a patient undergoing an MRI procedure at 3 Tesla or less. PMID:26266051

RF Phase Reference Distribution System for the TESLA Technology Based Projects

CERN Document Server

Czuba, K; Romaniuk, R S

2013-01-01

Since many decades physicists have been building particle accelerators and usually new projects became more advanced, more complicated and larger than predecessors. The importance and complexity of the phase reference distribution systems used in these accelerators have grown significantly during recent years. Amongst the most advanced of currently developed accelerators are projects based on the TESLA technology. These projects require synchronization of many RF devices with accuracy reaching femtosecond levels over kilometre distances. Design of a phase reference distribution system fulfilling such requirements is a challenging scientific task. There are many interdisciplinary problems which must be solved during the system design. Many, usually negligible issues, may became very important in such system. Furthermore, the design of a distribution system on a scale required for the TESLA technology based projects is a new challenge and there is almost no literature sufficiently covering this subject. This th...

Coupled Photonic Crystal Cavity Array Laser

DEFF Research Database (Denmark)

Schubert, Martin

in the quadratic lattice. Processing techniques are developed and optimized in order fabricate photonic crystals membranes in gallium arsenide with quantum dots as gain medium and in indium gallium arsenide phosphide with quantum wells as gain medium. Several key issues in process to ensure good quality....... The results are in good agreement with standard coupled mode theory. Also a novel type of photonic crystal structure is proposed called lambda shifted cavity which is a twodimensional photonic crystal laser analog of a VCSEL laser. Detailed measurements of the coupled modes in the photonic crystals...... with quantum dots are carried out. In agreement with a simple gain model the structures do not show stimulated emission. The spectral splitting due to the coupling between single cavities as well as arrays of cavities is studied theoretically and experimentally. Lasing is observed for photonic crystal cavity...

A two-cavity reactor for solar chemical processes: heat transfer model and application to carbothermic reduction of ZnO

International Nuclear Information System (INIS)

Wieckert, Christian; Palumbo, Robert; Frommherz, Ulrich

2004-01-01

A 5 kW two-cavity beam down reactor for the solar thermal decomposition of ZnO with solid carbon has been developed and tested in a solar furnace. Initial exploratory experiments show that it operates with a solar to chemical energy conversion efficiency of about 15% when the solar flux entering the reactor is 1300 kW/m 2 , resulting in a reaction chamber temperature of about 1500 K. The solid products have a purity of nearly 100% Zn. Furthermore, the reactor has been described by a numerical model that combines radiant and conduction heat transfer with the decomposition kinetics of the ZnO-carbon reaction. The model is based on the radiosity exchange method. For a given solar input, the model estimates cavity temperatures, Zn production rates, and the solar to chemical energy conversion efficiency. The model currently makes use of two parameters which are determined from the experimental results: conduction heat transfer through the reactor walls enters the model as a lumped term that reflects the conduction loss during the experiments, and the rate of the chemical reaction includes an experimentally determined term that reflects the effective amount of ZnO and CO participating in the reactor. The model output matches well the experimentally determined cavity temperatures. It suggests that reactors built with this two-cavity concept already on this small scale can reach efficiencies exceeding 25%, if operated with a higher solar flux or if one can reduce conduction heat losses through better insulation and if one can maintain or improve the effective amount of ZnO and CO that participates in the reaction

Modelling of the nonlinear soliton dynamics in the ring fibre cavity

Science.gov (United States)

Razukov, Vadim A.; Melnikov, Leonid A.

2018-04-01

Using the cabaret method numerical realization, long-time spatio-temporal dynamics of the electromagnetic field in a nonlinear ring fibre cavity with dispersion is investigated during the hundreds of round trips. Formation of both the temporal cavity solitons and irregular pulse trains is demonstrated and discussed.

Diffusion tensor imaging of the spinal cord at 1.5 and 3.0 Tesla

Energy Technology Data Exchange (ETDEWEB)

Rossi, C. [Radiologische Universitaetsklinik, Tuebingen (Germany). Sektion fuer Experimentelle Radiologie; CNR-INFM CRS-Soft, La Sapienza-Univ. Roma (Italy); Enrico Fern Center, Roma (Italy); Boss, A.; Martirosian, P.; Steidle, G.; Schick, F. [Radiologische Universitaetsklinik, Tuebingen (Germany). Sektion fuer Experimentelle Radiologie; Lindig, T.M. [Enrico Fern Center, Roma (Italy); Radiologische Universitaetsklinik, Tuebingen (Germany). Sektion fuer Experimentelle Kernspinresonanz des ZNS; Universitaetsklinikum Tuebingen (Germany). Zentrum fuer Neurologie und Hertie-Inst. fuer klinische Hirnforschung; Maetzler, W. [Universitaetsklinikum Tuebingen (Germany). Zentrum fuer Neurologie und Hertie-Inst. fuer klinische Hirnforschung; Claussen, C.D. [Radiologische Universitaetsklinik, Tuebingen (Germany). Abt. fuer Radiologische Diagnostik; Klose, U. [Radiologische Universitaetsklinik, Tuebingen (Germany). Sektion fuer Experimentelle Kernspinresonanz des ZNS

2007-03-15

Purpose: The feasibility of highly resolved diffusion tensor imaging (DTI) of the human cervical spinal cord was tested on a clinical MR unit operating at 3.0 Tesla. DTI parametrical maps and signal-to-noise ratios (SNRs) were compared to results recorded at 1.5 Tesla. Materials and Methods: Eight healthy volunteers and one patient participated in the study. A transverse oriented single-shot ECG-triggered echo-planar imaging (EPI) sequence with double spin-echo diffusion preparation was applied for highly resolved DTI of the spinal cord. The signal yield, fractional anisotropy (FA), and mean diffusivity (MD) were compared for both field strengths. The clinical applicability of the protocol was also tested in one patient with amyotrophic lateral sclerosis (ALS) at 3.0 T. Results: A mean increase in SNR of 95.7 {+-} 4.6% was found at 3.0 Tesla compared to 1.5 Tesla. Improved quality of the DTI parametrical maps was observed at higher field strength (p < 0.02). Comparable FA and MD (reported in units of 10 - 3 mm2/s) values were computed in the dorsal white matter at both field strengths (1.5 T: FA = 0.75 {+-} 0.08, MD = 0.84 {+-} 0.12, 3.0 T: FA = 0.74 {+-} 0.04, MD = 0.93 {+-} 0.14). The DTI images exhibited diagnostic image quality in the patient. At the site of the diseased corticospinal tract, a decrease of 46.0 {+-} 3.8% in FA (0.40 {+-} 0.03) and an increase of 50.3 {+-} 5.6% in MD (1.40 {+-} 0.05) were found in the ALS patient. (orig.)

Diffusion tensor imaging of the spinal cord at 1.5 and 3.0 Tesla

International Nuclear Information System (INIS)

Rossi, C.; Boss, A.; Martirosian, P.; Steidle, G.; Schick, F.; Lindig, T.M.; Radiologische Universitaetsklinik, Tuebingen; Universitaetsklinikum Tuebingen; Maetzler, W.; Claussen, C.D.; Klose, U.

2007-01-01

Purpose: The feasibility of highly resolved diffusion tensor imaging (DTI) of the human cervical spinal cord was tested on a clinical MR unit operating at 3.0 Tesla. DTI parametrical maps and signal-to-noise ratios (SNRs) were compared to results recorded at 1.5 Tesla. Materials and Methods: Eight healthy volunteers and one patient participated in the study. A transverse oriented single-shot ECG-triggered echo-planar imaging (EPI) sequence with double spin-echo diffusion preparation was applied for highly resolved DTI of the spinal cord. The signal yield, fractional anisotropy (FA), and mean diffusivity (MD) were compared for both field strengths. The clinical applicability of the protocol was also tested in one patient with amyotrophic lateral sclerosis (ALS) at 3.0 T. Results: A mean increase in SNR of 95.7 ± 4.6% was found at 3.0 Tesla compared to 1.5 Tesla. Improved quality of the DTI parametrical maps was observed at higher field strength (p < 0.02). Comparable FA and MD (reported in units of 10 - 3 mm2/s) values were computed in the dorsal white matter at both field strengths (1.5 T: FA = 0.75 ± 0.08, MD = 0.84 ± 0.12, 3.0 T: FA 0.74 ± 0.04, MD = 0.93 ± 0.14). The DTI images exhibited diagnostic image quality in the patient. At the site of the diseased corticospinal tract, a decrease of 46.0 ± 3.8% in FA (0.40 ± 0.03) and an increase of 50.3 ± 5.6% in MD (1.40 ± 0.05) were found in the ALS patient. (orig.)

Axonal diameter and density estimated with 7-Tesla hybrid diffusion imaging in transgenic Alzheimer rats

OpenAIRE

Daianu, Madelaine; Jacobs, Russell E.; Town, Terrence; Thompson, Paul M.

2016-01-01

Diffusion-weighted MR imaging (DWI) is a powerful tool to study brain tissue microstructure. DWI is sensitive to subtle changes in the white matter (WM), and can provide insight into abnormal brain changes in diseases such as Alzheimer’s disease (AD). In this study, we used 7-Tesla hybrid diffusion imaging (HYDI) to scan 3 transgenic rats (line TgF344-AD; that model the full clinico-pathological spectrum of the human disease) ex vivo at 10, 15 and 24 months. We acquired 300 DWI volumes across...

Orion EFT-1 Cavity Heating Tile Experiments and Environment Reconstruction

Science.gov (United States)

Salazar, Giovanni; Amar, Adam; Oliver, Brandon; Hyatt, Andrew; Rezin, Marc

2016-01-01

Developing aerothermodynamic environments for deep cavities, such as those produced by micrometeoroids and orbital debris impacts, poses a great challenge for engineers. In order to assess existing cavity heating models, two one-inch diameter cavities were flown on the Orion Multi-Purpose Crew Vehicle during Exploration Flight Test 1 (EFT1). These cavities were manufactured with depths of 1.0 in and 1.4 in, and they were both instrumented. Instrumentation included surface thermocouples upstream, downstream and within the cavities, and additional thermocouples at the TPS-structure interface. This paper will present the data obtained, and comparisons with computational predictions will be shown. Additionally, the development of a 3D material thermal model will be described, which will be used to account for the three-dimensionality of the problem when interpreting the data. Furthermore, using a multi-dimensional inverse heat conduction approach, a reconstruction of a time- and space-dependent flight heating distribution during EFT1 will be presented. Additional discussions will focus on instrumentation challenges and calibration techniques specific to these experiments. The analysis shown will highlight the accuracies and/or deficiencies of current computational techniques to model cavity flows during hypersonic re-entry.

Main features of nucleation in model solutions of oral cavity

Science.gov (United States)

Golovanova, O. A.; Chikanova, E. S.; Punin, Yu. O.

2015-05-01

The regularities of nucleation in model solutions of oral cavity have been investigated, and the induction order and constants have been determined for two systems: saliva and dental plaque fluid (DPF). It is shown that an increase in the initial supersaturation leads to a transition from the heterogeneous nucleation of crystallites to a homogeneous one. Some additives are found to enhance nucleation: HCO{3/-} > C6H12O6 > F-, while others hinder this process: protein (casein) > Mg2+. It is established that crystallization in DPF occurs more rapidly and the DPF composition is favorable for the growth of small (52.6-26.1 μm) crystallites. On the contrary, the conditions implemented in the model saliva solution facilitate the formation of larger (198.4-41.8 μm) crystals.

Measurements on the SPS 200 MHz Travelling Wave Cavity towards an Impedance Model

CERN Document Server

Roggen, Toon; Caspers, Fritz; Vollinger, Christine; CERN. Geneva. ATS Department

2016-01-01

This note discusses the contribution of the SPS 200 MHz TWC (Travelling Wave Cavity) to the SPS longitudinal impedance model. The measurement method and setup is briefly explained and a comparison with simulations is discussed for both the fundamental pass band (FPB) as well as the Higher Order Modes (HOMs). In addition a number of improvements to the measurement setup are discussed.

Focused tight dressing does not prevent cochlear implant magnet migration under 1.5 Tesla MRI.

Science.gov (United States)

Cuda, D; Murri, A; Succo, G

2013-04-01

We report a retrospective case of inner magnet migration, which occurred after 1.5 Tesla MRI scanning in an adult recipient of a bilateral cochlear implant (CI) despite a focused head dressing. The patient, bilaterally implanted with Nucleus 5 CIs (Cochlear LTD, Sydney, Australia), underwent a 1.5 Tesla cholangio-MRI scan for biliary duct pathology. In subsequent days, a focal skin alteration appeared over the left inner coil. Plain skull radiographs showed partial magnet migration on the left side. Surgical exploration confirmed magnet twisting; the magnet was effectively repositioned. Left CI performance was restored to pre-migration level. The wound healed without complications. Thus, focused dressing does not prevent magnet migration in CI recipients undergoing 1.5 Tesla MRI. All patients should be counselled on this potential complication. A minor surgical procedure is required to reposition the magnet. Nevertheless, timely diagnosis is necessary to prevent skin breakdown and subsequent device contamination. Plain skull radiograph is very effective in identifying magnet twisting; it should be performed systematically after MRI or minimally on all suspected cases.

Tuned cavity magnetometer sensitivity.

Energy Technology Data Exchange (ETDEWEB)

Okandan, Murat; Schwindt, Peter

2009-09-01

We have developed a high sensitivity (Tesla/{radical}Hz), non-cryogenic magnetometer that utilizes a novel optical (interferometric) detection technique. Further miniaturization and low-power operation are key advantages of this magnetometer, when compared to systems using SQUIDs which require liquid Helium temperatures and associated overhead to achieve similar sensitivity levels.

Ultimate Gradient Limitation in Niobium Superconducting Accelerating Cavities

Energy Technology Data Exchange (ETDEWEB)

Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Grassellino, Anna [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Martinello, Martina [Illinois Inst. of Technology, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Posen, Sam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Romanenko, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zasadzinski, John [Illinois Inst. of Technology, Chicago, IL (United States)

2016-06-01

The present study is addressed to the theoretical description of the ultimate gradient limitation in SRF cavities. Our intent is to exploit experimental data to confirm models which provide feed-backs on how to improve the current state-of-art. New theoretical insight on the cavities limiting factor can be suitable to improve the quench field of N-doped cavities, and therefore to take advantage of high Q₀ at high gradients.

RF cavity evaluation with the code SUPERFISH

International Nuclear Information System (INIS)

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

1982-01-01

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

SU-F-T-43: Prediction of Dose Increments by Brain Metastases Resection Cavity Shrinkage Model with I-125 and Cs-131 LDR Seed Implantations

Energy Technology Data Exchange (ETDEWEB)

Han, D; Braunstein, S; Sneed, P; McDermott, M; Ma, L [University of California San Francisco, San Francisco, CA (United States)

2016-06-15

Purpose: This work aims to determine dose variability via a brain metastases resection cavity shrinkage model (RC-SM) with I-125 or Cs-131 LDR seed implantations. Methods: The RC-SM was developed to represent sequential volume changes of 95 consecutive brain metastases patients. All patients underwent serial surveillance MR and change in cavity volume was recorded for each patient. For the initial resection cavity, a prolate-ellipsoid cavity model was suggested and applied volume shrinkage rates to correspond to 1.7, 3.6, 5.9, 11.7, and 20.5 months after craniotomy. Extra-ring structure (6mm) was added on a surface of the resection volume and the same shrinkage rates were applied. Total 31 LDR seeds were evenly distributed on the surface of the resection cavity. The Amersham 6711 I-125 seed model (Oncura, Arlington Heights, IL) and the Model Cs-1 Rev2 Cs-131 seed model (IsoRay, Richland, WA) were used for TG-43U1 dose calculation and in-house-programed 3D-volumetric dose calculation system was used for resection cavity rigid model (RC-RM) and the RC-SM dose calculation. Results: The initial resection cavity volume shrunk to 25±6%, 35±6.8%, 42±7.7%, 47±9.5%, and 60±11.6%, with respect to sequential MR images post craniotomy, and the shrinkage rate (SR) was calculated as SR=56.41Xexp(−0.2024Xt)+33.99 and R-square value was 0.98. The normal brain dose as assessed via the dose to the ring structure with the RC-SM showed 29.34% and 27.95% higher than the RC-RM, I-125 and Cs-131, respectively. The dose differences between I-125 and Cs-131 seeds within the same models, I-125 cases were 9.17% and 10.35% higher than Cs-131 cases, the RC-RM and the RC-SM, respectively. Conclusion: A realistic RC-SM should be considered during LDR brain seed implementation and post-implement planning to prevent potential overdose. The RC-SM calculation shows that Cs-131 is more advantageous in sparing normal brain as the resection cavity volume changes with the LDR seeds implementation.

Simulations of the TESLA Linear Collider with a Fast Feedback System

CERN Document Server

Schulte, Daniel; White, G

2003-01-01

The tolerances on the beams as they collide at the interaction point of the TESLA linear collider are very tight due to the nano-metre scale final vertical bunch spot sizes. Ground motion causes the beams to increase in emittance and drift out of collision leading to dramatic degradation of luminosity performance. To combat this, both slow orbit and fast intra-train feedback systems will be used. The design of these feedback systems depends critically on how component misalignment effects the beam throughout the whole accelerator. A simulation has been set up to study in detail the accelerator performance under such conditions by merging the codes of PLACET, MERLIN and GUINEA-PIG together with Simulink code to model feedback systems, all under a Matlab environment.

Testing of plain and fibrous concrete single cavity prestressed concrete reactor vessel models

International Nuclear Information System (INIS)

Oland, C.B.

1985-01-01

Two single-cavity prestressed concrete reactor vessel (PCRV) models were fabricated and tested to failure to demonstrate the structural response and ultimate pressure capacity of models cast from high-strength concretes. Concretes with design compressive strengths in excess of 70 MPa (10,000 psi) were developed for this investigation. One model was cast from plain concrete and failed in shear at the head region. The second model was cast from fiber reinforced concrete and failed by rupturing the circumferential prestressing at the sidewall of the structure. The tests also demonstrated the capabilities of the liner system to maintain a leak-tight pressure boundary. 3 refs., 4 figs

Modeling nest survival of cavity-nesting birds in relation to postfire salvage logging

Science.gov (United States)

Vicki Saab; Robin E. Russell; Jay Rotella; Jonathan G. Dudley

2011-01-01

Salvage logging practices in recently burned forests often have direct effects on species associated with dead trees, particularly cavity-nesting birds. As such, evaluation of postfire management practices on nest survival rates of cavity nesters is necessary for determining conservation strategies. We monitored 1,797 nests of 6 cavity-nesting bird species: Lewis'...

Comparison of Deep Brain Stimulation Lead Targeting Accuracy and Procedure Duration between 1.5- and 3-Tesla Interventional Magnetic Resonance Imaging Systems: An Initial 12-Month Experience.

Science.gov (United States)

Southwell, Derek G; Narvid, Jared A; Martin, Alastair J; Qasim, Salman E; Starr, Philip A; Larson, Paul S

2016-01-01

Interventional magnetic resonance imaging (iMRI) allows deep brain stimulator lead placement under general anesthesia. While the accuracy of lead targeting has been described for iMRI systems utilizing 1.5-tesla magnets, a similar assessment of 3-tesla iMRI procedures has not been performed. To compare targeting accuracy, the number of lead targeting attempts, and surgical duration between procedures performed on 1.5- and 3-tesla iMRI systems. Radial targeting error, the number of targeting attempts, and procedure duration were compared between surgeries performed on 1.5- and 3-tesla iMRI systems (SmartFrame and ClearPoint systems). During the first year of operation of each system, 26 consecutive leads were implanted using the 1.5-tesla system, and 23 consecutive leads were implanted using the 3-tesla system. There was no significant difference in radial error (Mann-Whitney test, p = 0.26), number of lead placements that required multiple targeting attempts (Fisher's exact test, p = 0.59), or bilateral procedure durations between surgeries performed with the two systems (p = 0.15). Accurate DBS lead targeting can be achieved with iMRI systems utilizing either 1.5- or 3-tesla magnets. The use of a 3-tesla magnet, however, offers improved visualization of the target structures and allows comparable accuracy and efficiency of placement at the selected targets. © 2016 S. Karger AG, Basel.

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.

A case study testing the cavity mode model of the magnetosphere

Directory of Open Access Journals (Sweden)

D. V. Sarafopoulos

2005-07-01

Full Text Available Based on a case study we test the cavity mode model of the magnetosphere, looking for eigenfrequencies via multi-satellite and multi-instrument measurements. Geotail and ACE provide information on the interplanetary medium that dictates the input parameters of the system; the four Cluster satellites monitor the magnetopause surface waves; the POLAR (L=9.4 and LANL 97A (L=6.6 satellites reveal two in-situ monochromatic field line resonances (FLRs with T=6 and 2.5 min, respectively; and the IMAGE ground magnetometers demonstrate latitude dependent delays in signature arrival times, as inferred by Sarafopoulos (2004b. Similar dispersive structures showing systematic delays are also extensively scrutinized by Sarafopoulos (2005 and interpreted as tightly associated with the so-called pseudo-FLRs, which show almost the same observational characteristics with an authentic FLR. In particular for this episode, successive solar wind pressure pulses produce recurring ionosphere twin vortex Hall currents which are identified on the ground as pseudo-FLRs. The BJN ground magnetometer records the pseudo-FLR (alike with the other IMAGE station responses associated with an intense power spectral density ranging from 8 to 12 min and, in addition, two discrete resonant lines with T=3.5 and 7 min. In this case study, even though the magnetosphere is evidently affected by a broad-band compressional wave originated upstream of the bow shock, nevertheless, we do not identify any cavity mode oscillation within the magnetosphere. We fail, also, to identify any of the cavity mode frequencies proposed by Samson (1992.

Keywords. Magnetospheric physics (Magnetosphereionosphere interactions; Solar wind-magnetosphere interactions; MHD waves and instabilities

Segmented trapped vortex cavity

Science.gov (United States)

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

2010-01-01

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

A numerically efficient damping model for acoustic resonances in microfluidic cavities

Energy Technology Data Exchange (ETDEWEB)

Hahn, P., E-mail: hahnp@ethz.ch; Dual, J. [Institute of Mechanical Systems (IMES), Department of Mechanical and Process Engineering, ETH Zurich, Tannenstrasse 3, CH-8092 Zurich (Switzerland)

2015-06-15

Bulk acoustic wave devices are typically operated in a resonant state to achieve enhanced acoustic amplitudes and high acoustofluidic forces for the manipulation of microparticles. Among other loss mechanisms related to the structural parts of acoustofluidic devices, damping in the fluidic cavity is a crucial factor that limits the attainable acoustic amplitudes. In the analytical part of this study, we quantify all relevant loss mechanisms related to the fluid inside acoustofluidic micro-devices. Subsequently, a numerical analysis of the time-harmonic visco-acoustic and thermo-visco-acoustic equations is carried out to verify the analytical results for 2D and 3D examples. The damping results are fitted into the framework of classical linear acoustics to set up a numerically efficient device model. For this purpose, all damping effects are combined into an acoustofluidic loss factor. Since some components of the acoustofluidic loss factor depend on the acoustic mode shape in the fluid cavity, we propose a two-step simulation procedure. In the first step, the loss factors are deduced from the simulated mode shape. Subsequently, a second simulation is invoked, taking all losses into account. Owing to its computational efficiency, the presented numerical device model is of great relevance for the simulation of acoustofluidic particle manipulation by means of acoustic radiation forces or acoustic streaming. For the first time, accurate 3D simulations of realistic micro-devices for the quantitative prediction of pressure amplitudes and the related acoustofluidic forces become feasible.

[Nikola Tesla: flashes of inspiration].

Science.gov (United States)

Villarejo-Galende, Albero; Herrero-San Martín, Alejandro

2013-01-16

Nikola Tesla (1856-1943) was one of the greatest inventors in history and a key player in the revolution that led to the large-scale use of electricity. He also made important contributions to such diverse fields as x-rays, remote control, radio, the theory of consciousness or electromagnetism. In his honour, the international unit of magnetic induction was named after him. Yet, his fame is scarce in comparison with that of other inventors of the time, such as Edison, with whom he had several heated arguments. He was a rather odd, reserved person who lived for his inventions, the ideas for which came to him in moments of inspiration. In his autobiography he relates these flashes with a number of neuropsychiatric manifestations, which can be seen to include migraine auras, synaesthesiae, obsessions and compulsions.

Status of the GA/MCA 12 Tesla Coil Development Program

International Nuclear Information System (INIS)

Alcorn, J.S.; Purcell, J.R.; Chen, W.Y.; Hsu, Y.H.

1980-09-01

The current status of the Team One effort of the DOE/OFE/D and T 12 Tesla Coil Development Program is presented. Subatmospheric, helium bath cooled, NbTiTa alloy is employed for the test coil, and ETF TF-coil concept. General Atomic is the Team One leader, with Magnetic Corporation of American as industrial subcontractor

Tesla coil discharges guided by femtosecond laser filaments in air

Science.gov (United States)

Brelet, Yohann; Houard, Aurélien; Arantchouk, Leonid; Forestier, Benjamin; Liu, Yi; Prade, Bernard; Carbonnel, Jérôme; André, Yves-Bernard; Mysyrowicz, André

2012-04-01

A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 kHz synchronisable with a nanosecond temporal jitter. Using this compact high voltage generator, we demonstrate reproducible meter long discharges in air at a repetition rate of 1 Hz. Triggering and guiding of the discharges are performed in air by femtosecond laser filaments.

Wall compliance and violin cavity modes.

Science.gov (United States)

Bissinger, George

2003-03-01

Violin corpus wall compliance, which has a substantial effect on cavity mode frequencies, was added to Shaw's two-degree-of-freedom (2DOF) network model for A0 ("main air") and A1 (lowest length mode included in "main wood") cavity modes. The 2DOF model predicts a V(-0.25) volume dependence for A0 for rigid violin-shaped cavities, to which a semiempirical compliance correction term, V(-x(c)) (optimization parameter x(c)) consistent with cavity acoustical compliance and violin-based scaling was added. Optimizing x(c) over A0 and A1 frequencies measured for a Hutchins-Schelleng violin octet yielded x(c) approximately 0.08. This markedly improved A0 and A1 frequency predictions to within approximately +/- 10% of experiment over a range of about 4.5:1 in length, 10:1 in f-hole area, 3:1 in top plate thickness, and 128:1 in volume. Compliance is a plausible explanation for A1 falling close to the "main wood" resonance, not increasingly higher for the larger instruments, which were scaled successively shorter compared to the violin for ergonomic and practical reasons. Similarly incorporating compliance for A2 and A4 (lowest lower-/upper-bout modes, respectively) improves frequency predictions within +/-20% over the octet.

Implosion of the small cavity and large cavity cannonball targets

International Nuclear Information System (INIS)

Nishihara, Katsunobu; Yamanaka, Chiyoe.

1984-01-01

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

Hydrodynamic Drag on Streamlined Projectiles and Cavities

KAUST Repository

Jetly, Aditya

2016-04-19

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

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

Science.gov (United States)

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

2014-05-13

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

Nonlinear Analysis of Cavities in Rock Salt

DEFF Research Database (Denmark)

Ottosen, N. S.; Krenk, Steen

1979-01-01

The paper covers some material and computational aspects of the rock mechanics of leached cavities in salt. A material model is presented in which the instantaneous stiffness of the salt is obtained by interpolation between the unloaded state and a relevant failure state. The model enables predic...... prediction of short term triaxial behaviour from uniaxial stress-strain curves. Key results from a nonlinear finite element calculation of a gas-filled cavity are given, and the general features are related to a simple nonlinear method of stress evaluation....

Single-cell LEP-type cavity on measurement stand

CERN Multimedia

CERN PhotoLab

1982-01-01

A single-cell cavity, made of copper, with tapered connectors for impedance measurements. It was used as a model of LEP-type superconducting cavities, to investigate impedance and higher-order modes and operated at around 600 MHz (the LEP acceleration frequency was 352.2 MHz). See 8202500.

An open data repository and a data processing software toolset of an equivalent Nordic grid model matched to historical electricity market data

Directory of Open Access Journals (Sweden)

Luigi Vanfretti

2017-04-01

This Nordic 44 equivalent model was also used in iTesla project (iTesla [3] to carry out simulations within a dynamic security assessment toolset (iTesla, 2016 [4], and has been further enhanced during the ITEA3 OpenCPS project (iTEA3 [5]. The raw, processed data and output models utilized within the iTesla platform (iTesla, 2016 [4] are also available in the repository. The CIM and Modelica snapshots of the “Nordic 44” model for the year 2015 are available in a Zenodo repository.

Use of Tesla NZK 203 neutron probe in studying water as geochemical factor in weathering zone

International Nuclear Information System (INIS)

Hally, J.

1980-01-01

The Tesla NZK 203 neutron moisture gage was used for determining soil moisture in depths of 1 and 2 meters in the Luha-Kacerov profile in the Zelivka water reservoir basin. The borehole spacing was 100 m. Measurements were made once a month between May and October 1978. The results were compared with the granulometric composition and the values of the specific surface areas of earths in the area. The Tesla NZK 203 moisture gage was fully proven for speedy measurement of volume moisture at constant measuring points. (Ha)

Elon Musk – riskanter Milliardenpoker um Tesla & Co.

OpenAIRE

Lipp, Reto

2017-01-01

Interview von Reto Lipp mit Peter Leibfried (SRF ECO): Von seinen Fans wird er wie ein Rockstar gefeiert. Ob Tesla, Solar City oder SpaceX, Elon Musk will die Welt revolutionieren. Doch seine Visionen verschlingen Unsummen. Bisher ist es ihm stets gelungen, neue Gelder zu mobilisieren und bei Bedarf Millionenbeträge zwischen seinen Unternehmen hin und her zu schieben. Doch das Firmenimperium lebt von riesigen Erwartungen der Investoren. Kann Elon Musk sie nicht einlösen, droht der Kollaps.

Cavity-ligand binding in a simple two-dimensional water model

Directory of Open Access Journals (Sweden)

G. Mazovec

2016-02-01

Full Text Available By means of Monte Carlo computer simulations in the isothermal-isobaric ensemble, we investigated the interaction of a hydrophobic ligand with the hydrophobic surfaces of various curvatures (planar, convex and concave. A simple two-dimensional model of water, hydrophobic ligand and surface was used. Hydration/dehidration phenomena concerning water molecules confined close to the molecular surface were investigated. A notable dewetting of the hydrophobic surfaces was observed together with the reorientation of the water molecules close to the surface. The hydrogen bonding network was formed to accommodate cavities next to the surfaces as well as beyond the first hydration shell. The effects were most strongly pronounced in the case of concave surfaces having large curvature. This simplified model can be further used to evaluate the thermodynamic fingerprint of the docking of hydrophobic ligands.

A parametric study on the PD pulses activity within micro-cavities

Science.gov (United States)

Ganjovi, Alireza A.

2016-03-01

A two-dimensional kinetic model has been used to parametric investigation of the spark-type partial discharge pulses inside the micro-cavities. The model is based on particle-in-cell methods with Monte Carlo Collision techniques for modeling of collisions. Secondary processes like photo-emission and cathode-emission are considered. The micro-cavity may be sandwiched between two metallic conductors or two dielectrics. The discharge within the micro-cavity is studied in conjunction with the external circuit. The model is used to successfully simulate the evolution of the discharge and yield useful information about the build-up of space charge within the micro-cavity and the consequent modification of the applied electric field. The phase-space scatter plots for electrons, positive, and negative ions are obtained in order to understand the manner in which discharge progresses over time. The rise-time and the magnitude of the discharge current pulse are obtained and are seen to be affected by micro-cavity dimensions, gas pressure within the micro-cavity, and the permittivity of surrounding dielectrics. The results have been compared with existing experimental, theoretical, and computational results, wherever possible. An attempt has been made to understand the nature of the variations in terms of the physical processes involved.

Implementation of fast macromolecular proton fraction mapping on 1.5 and 3 Tesla clinical MRI scanners: preliminary experience

Science.gov (United States)

Yarnykh, V.; Korostyshevskaya, A.

2017-08-01

Macromolecular proton fraction (MPF) is a biophysical parameter describing the amount of macromolecular protons involved into magnetization exchange with water protons in tissues. MPF represents a significant interest as a magnetic resonance imaging (MRI) biomarker of myelin for clinical applications. A recent fast MPF mapping method enabled clinical translation of MPF measurements due to time-efficient acquisition based on the single-point constrained fit algorithm. However, previous MPF mapping applications utilized only 3 Tesla MRI scanners and modified pulse sequences, which are not commonly available. This study aimed to test the feasibility of MPF mapping implementation on a 1.5 Tesla clinical scanner using standard manufacturer’s sequences and compare the performance of this method between 1.5 and 3 Tesla scanners. MPF mapping was implemented on 1.5 and 3 Tesla MRI units of one manufacturer with either optimized custom-written or standard product pulse sequences. Whole-brain three-dimensional MPF maps obtained from a single volunteer were compared between field strengths and implementation options. MPF maps demonstrated similar quality at both field strengths. MPF values in segmented brain tissues and specific anatomic regions appeared in close agreement. This experiment demonstrates the feasibility of fast MPF mapping using standard sequences on 1.5 T and 3 T clinical scanners.

Modulation of cavity-polaritons by surface acoustic waves

DEFF Research Database (Denmark)

de Lima, M. M.; Poel, Mike van der; Hey, R.

2006-01-01

We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations.......We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations....

Analysis of short-term reactor cavity transient

International Nuclear Information System (INIS)

Cheng, T.C.; Fischer, S.R.

1981-01-01

Following the transient of a hypothetical loss-of-coolant accident (LOCA) in a nuclear reactor, peak pressures are reached within the first 0.03 s at different locations inside the reactor cavity. Due to the complicated multidimensional nature of the reactor cavity, the short-term analysis of the LOCA transient cannot be performed by using traditional containment codes, such as CONTEMPT. The advanced containment code, BEACON/MOD3, developed at the Idaho National Engineering Laboratory (INEL), can be adapted for such analysis. This code provides Eulerian, one and two-dimensional, nonhomogeneous, nonequilibrium flow modeling as well as lumped parameter, homogeneous, equilibrium flow modeling for the solution of two-component, two-phase flow problems. The purpose of this paper is to demonstrate the capability of the BEACON code to analyze complex containment geometry such as a reactor cavity

The influence of spherical cavity surface charge distribution on the sequence of partial discharge events

International Nuclear Information System (INIS)

Illias, Hazlee A; Chen, George; Lewin, Paul L

2011-01-01

In this work, a model representing partial discharge (PD) behaviour of a spherical cavity within a homogeneous dielectric material has been developed to study the influence of cavity surface charge distribution on the electric field distribution in both the cavity and the material itself. The charge accumulation on the cavity surface after a PD event and charge movement along the cavity wall under the influence of electric field magnitude and direction has been found to affect the electric field distribution in the whole cavity and in the material. This in turn affects the likelihood of any subsequent PD activity in the cavity and the whole sequence of PD events. The model parameters influencing cavity surface charge distribution can be readily identified; they are the cavity surface conductivity, the inception field and the extinction field. Comparison of measurement and simulation results has been undertaken to validate the model.

The influence of spherical cavity surface charge distribution on the sequence of partial discharge events

Energy Technology Data Exchange (ETDEWEB)

Illias, Hazlee A [Department of Electrical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Chen, George; Lewin, Paul L, E-mail: h.illias@um.edu.my [Tony Davies High Voltage Laboratory, School of Electronics and Computer Science, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

2011-06-22

In this work, a model representing partial discharge (PD) behaviour of a spherical cavity within a homogeneous dielectric material has been developed to study the influence of cavity surface charge distribution on the electric field distribution in both the cavity and the material itself. The charge accumulation on the cavity surface after a PD event and charge movement along the cavity wall under the influence of electric field magnitude and direction has been found to affect the electric field distribution in the whole cavity and in the material. This in turn affects the likelihood of any subsequent PD activity in the cavity and the whole sequence of PD events. The model parameters influencing cavity surface charge distribution can be readily identified; they are the cavity surface conductivity, the inception field and the extinction field. Comparison of measurement and simulation results has been undertaken to validate the model.

FPGA and optical-network-based LLRF distributed control system for TESLA-XFEL linear accelerator

Science.gov (United States)

Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Czarski, Tomasz; Giergusiewicz, Wojciech; Jalmuzna, Wojciech; Olowski, Krysztof; Perkuszewski, Karol; Zielinski, Jerzy; Simrock, Stefan

2005-02-01

The work presents a structural and functional model of a distributed low level radio frequency (LLRF) control system for the TESLA-XFEL accelerator. The design of a system basing on the FPGA chips and multi-gigabit optical network was debated. The system design approach was fully parametric. The major emphasis is put on the methods of the functional and hardware concentration to use fully both: a very big transmission capacity of the optical fiber telemetric channels and very big processing power of the latest series of the, DSP enhanced and optical I/O equipped, FPGA chips. The subject of the work is the design of a universal, laboratory module of the LLRF sub-system. Initial parameters of the system model under the design are presented.

MR cholangiopancreatography. Comparison of images obtained with 1.0 and 1.5 tesla units

International Nuclear Information System (INIS)

Yasui, Masayasu; Ito, Katsuyoshi; Koike, Shinji; Matsunaga, Naofumi

2002-01-01

The purpose of this study was to compare the image quality and visualization obtained in MR cholangiopancreatography (MRCP) using different high-field strength (1.0 vs. 1.5 Tesla) MR units and to assess the effect of field strength on MRCP. This study population included 10 healthy volunteers and 37 patients suspected of having pancreatobiliary diseases. MRCP images were obtained using two MR units with different high-field strengths (1.0 and 1.5 Tesla), with half-Fourier acquisition single-shot turbo spin-echo (HASTE) and rapid acquisition by relaxation enhancement (RARE) sequences. The image quality and visualization of each portion of the pancreatobiliary system were graded and recorded using a four-point scale. Additionally, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured. The SNR and CNR in HASTE sequences acquired with the 1.5 Tesla (T) unit were significantly higher than those acquired with the 1.0 T unit (p=0.001). In qualitative analysis, there were no statistically significant differences in image quality or visualization of the ducts in either HASTE or RARE sequences between 1.0 T and 1.5 T. Our study showed that visual image quality provided by MRCP was equivalent at 1.0 and 1.5 T. (author)

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.

Quantum and classical nonlinear dynamics in a microwave cavity

Energy Technology Data Exchange (ETDEWEB)

Meaney, Charles H.; Milburn, Gerard J. [The University of Queensland, Department of Physics, St Lucia, QLD (Australia); Nha, Hyunchul [Texas A and M University at Qatar, Department of Physics, PO Box 23874, Doha (Qatar); Duty, Timothy [The University of New South Wales, Department of Physics, Kensington, NSW (Australia)

2014-12-01

We consider a quarter wave coplanar microwave cavity terminated to ground via a superconducting quantum interference device. By modulating the flux through the loop, the cavity frequency is modulated. The flux is varied at twice the cavity frequency implementing a parametric driving of the cavity field. The cavity field also exhibits a large effective nonlinear susceptibility modelled as an effective Kerr nonlinearity, and is also driven by a detuned linear drive. We show that the semi-classical model corresponding to this system exhibits a fixed point bifurcation at a particular threshold of parametric pumping power. We show the quantum signature of this bifurcation in the dissipative quantum system. We further linearise about the below threshold classical steady state and consider it to act as a bifurcation amplifier, calculating gain and noise spectra for the corresponding small signal regime. Furthermore, we use a phase space technique to analytically solve for the exact quantum steady state. We use this solution to calculate the exact small signal gain of the amplifier. (orig.)

Red-cockaded woodpecker nest-cavity selection: relationships with cavity age and resin production

Science.gov (United States)

Richard N. Conner; Daniel Saenz; D. Craig Rudolph; William G. Ross; David L. Kulhavy

1998-01-01

The authors evaluated selection of nest sites by male red-cockaded woodpeckers (Picoides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpeckers were available and when both naturally excavated cavities and artificial cavities were available. They also evaluated nest-cavity selection relative to the ability of naturally...