Transverse beam coupling impedance of the CERN Proton Synchrotron
Persichelli, S.; Migliorati, M.; Biancacci, N.; Gilardoni, S.; Metral, E.; Salvant, B.
2016-04-01
Beam coupling impedance is a fundamental parameter to characterize the electromagnetic interaction of a particle beam with the surrounding environment. Synchrotron machine performances are critically affected by instabilities and collective effects triggered by beam coupling impedance. In particular, transverse beam coupling impedance is expected to impact beam dynamics of the CERN Proton Synchrotron (PS), since a significant increase in beam intensity is foreseen within the framework of the LHC Injectors Upgrade (LIU) project. In this paper we describe the study of the transverse beam coupling impedance of the PS, taking into account the main sources of geometrical impedance and the contribution of indirect space charge at different energies. The total machine impedance budget, determined from beam-based dedicated machine measurement sessions, is also discussed and compared with the theoretical model.
The beam coupling impedance model of CERN Proton Synchrotron
Persichelli, Serena; Migliorati, Mauro; Salvant, Benoit
The research activity described in this thesis work is dedicated to developing a longitudinal and a transverse beam coupling impedance model for the CERN Proton Synchrotron (PS), in the framework of the Large Hadron Collider (LHC) Injector Upgrade (LIU) project. The study allows a better understanding of the instability threshold of the machine, helping predicting the effects of the current increase planned for the upgrade program. Furthermore, the knowledge of the machine beam coupling impedance model allows improving the stability of beams injected into the LHC chain, in prevision for the particle collision energy increase in program for LHC physics experiments.
THE COUPLING IMPEDANCE OF A TOROIDAL BEAM TUBE WITH CIRCULAR CROSS SECTION
International Nuclear Information System (INIS)
IN THIS PAPER, THE LONGITUDINAL COUPLING IMPEDANCE OF A TOROIDAL BEAM TUBE WITH CIRCULAR CROSS SECION IS DERIVED IN THE FREQUENCY DOMAIN USING THE TOROIDAL COORDINATE SYSTEM. EXACT, ALTHOUGH COUPLED, DIFFERENTIAL EQUATIONS FOR THE AZIMUTHAL FIELD COMPONENTS ARE OBTAINED. AN APPROXIAMTE SOLUTION, VALID IN THE LIMIT OF SMALL CURVATURE, IS THEN DERIVED. ASSUMING EXTREME RELATIVISTIC ENERGIES AND A BEAM TUBE WITH PERFECTLY CONDUCTING WALLS, ONE FINDS A CLOSED-FORM EXPRESSION FOR THE PURELY REACTIVE COUPLING IMPEDANCE WHICH AT LOW MODE NUMBERS IS DEPENDENT ON THE TUBE GEOMETRY BUT WHICH AT VERY LARGE MODE NUMBERS APPROACHES THE FREE SPACE IMPEDANCE
Longitudinal coupling impedance of a hole in the accelerator beam pipe
International Nuclear Information System (INIS)
In the design of modern accelerators, an accurate estimate of coupling impedance is very important. The sources which give rise to coupling impedance are the geometric discontinuities in the accelerator beam pipe. In various discontinuities such as RF cavities, bellows, and collimators, the coupling impedance of the holes has not been well understood. Although coupling impedance can be obtained in general from the Fourier transform of the corresponding wake potential which may be obtained numerically, this is time consuming and requires a large amount of computer storage when applied to a small dimension of a discontinuity in a typical beam pipe, often imposing a fundamental limitation of the numerical approach. More fundamentally, however, numerical calculation does not have the predictive power because of limited understanding of how the coupling impedance of a hole should behave over a wide frequency range. This question was studied by developing a theoretical analysis based on a variational method. An analytical formula for the coupling impedance of a hole is developed in this work using a variational method. The result gives good qualitative agreements with the coupling impedances evaluated numerically from the Fourier transform of the wake potential which is obtained from the computer code MAFIA-T3. The author shows that the coupling impedance of a hole behaves quite similar to the impedance of an RLC-resonator circuit. Important parameters used to describe such a resonator circuit are the resonant frequency and bandwidth. The author provides a theoretical insight on how to parameterize properly the numerical impedance of a hole when data exhibit complicated dependence on frequency. This is possible because one can show that the parameters are a function of the dimensionless quantity kd alone, with k the free-space wave number and d the radius of hole
Beam Coupling Impedance of the New Beam Screen of the LHC Injection Kicker Magnets
Day, H; Caspers, F; Métral, E; Salvant, B; Uythoven, J
2014-01-01
The LHC injection kicker magnets experienced significant beam induced heating of the ferrite yoke, with high beam currents circulating for many hours, during operation of the LHC in 2011 and 2012. The causes of this beam induced heating were studied in depth and an improved beam screen implemented to reduce the impedance. Results of measurements and simulations of the new beam screen design are presented in this paper: these are used to predict power loss for operation after long shutdown 1 and for proposed HL-LHC operational parameters.
Single beam collective effects in FCC-ee due to beam coupling impedance
Belli, Eleonora; Persichelli, Serena; Zobov, Mikhail
2016-01-01
The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, is focused on proton-proton high-energy and electron-positron high-luminosity frontier machines. This new accelerator complex represents a great challenge under several aspects, which involve R&D on beam dynamics and new technologies. One very critical point in this context is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelera- tor are identified and evaluated, and their impact on the beam dynamics, which in some cases could l...
Single beam collective effects in FCC-ee due to beam coupling impedance
Belli, Eleonora; Persichelli, Serena; Zobov, Mikhail
2016-01-01
The Future Circular Collider study, hosted by CERN to design post-LHC particle accelerator options in a worldwide context, is focused on proton-proton high-energy and electron-positron high-luminosity frontier machines. This new accelerator complex represents a great challenge under several aspects, which involve R&D on beam dynamics and new technologies. One very critical point in this context is represented by collective effects, generated by the interaction of the beam with self-induced electromagnetic fields, called wake fields, which could produce beam instabilities, thus reducing the machines performance and limiting the maximum stored current. It is therefore very important to be able to predict these effects and to study in detail potential solutions to counteract them. In this paper the resistive wall and some other important geometrical sources of impedance for the FCC electron-positron accelerator are identified and evaluated, and their impact on the beam dynamics, which in some cases could lea...
Persichelli, S
2014-01-01
We present a study of the beam coupling impedance due to trapped modes of a new protection septum that will be installed in the CERN Proton Synchrotron (PS) during the Long Shutdown 1 (LS1). The interaction between the particle field and the discontinuities inside the septum generates electromagnetic fields localized in a particular region inside the device. These resonances, producing narrow peaks in the coupling impedance, can be potential source of beam instabilities for high intensity particle accelerators like PS. The final outcome of these studies is the basis for the acceptance of the septum installation in section 15 of the PS ring.
Beam-chamber interaction in accelerators. Methods for calculating coupling impedances
International Nuclear Information System (INIS)
A review of methods for calculating the coupling impedances of the vacuum chamber of accelerators is given. The definitions of the coupling impedances, their properties and relations to the wake potentials are discussed in detail. The main attention is paid to the techniques applied at low frequencies and in the resonant region. An attempt to classify these methods is made. The paper presents a collection of formulae and can be used as a reference guide. 126 refs.; 1 fig.; 1 tab
International Nuclear Information System (INIS)
Within the Bethe diffraction theory, the impedance of a small circular hole has been calculated for particle beams of arbitrary β and finite size via two approaches. In the first approach we define the impedance in terms of the total work done by the fields excited in the beam pipe, where it finally reduces to a surface integral over the hole region. In the second approach, the hole has been treated as a radiating electric and magnetic dipole with effective electric and magnetic moments resulting from fictitiously introduced surface charge and current densities. The above two approaches lead to exactly the same result for the hole impedance which is consistent with the predictions made by the Bethe theory for wavelengths that are much larger than the hole size. (author)
Impedance of a beam tube with antechamber
International Nuclear Information System (INIS)
A beam vacuum chamber was proposed to allow synchrotron light to radiate from a circulating electron beam into an antechamber containing photon targets, pumps, etc. To determine the impedance, electromagnetic measurements were carried out on a section of chamber using for low frequencies a current-carrying wire and for up to 16 GHz, a resonance perturbation method. Because the response of such a chamber would depend on upstream and downstream restrictions of aperture yet to be determined, the resonance studies were analyzed in some generality. The favorable conclusion of these studies is that the antechamber makes practically no contribution to either the longitudinal or the transverse impedances. The small beam tube with slot-isolated antechamber responds as a small cylinder up to the frequency (∼ 15 GHz) where energy can propagate transversely in the narrow slot. The important function of the slot is to prevent the beam from coupling to the many lower-frequency modes of the antechamber. If cut off frequency were higher than the slot-coupling at 15 GHz, only an increased density of modes is expected, with little change in average beam impedances
Analytic methods for calculating coupling impedances
International Nuclear Information System (INIS)
These lecture notes describe a variety of analytic techniques to calculate the longitudinal and transverse impedances of obstacles in a beam pipe. They also treat the effort to shield these impedances from the beam by appropriate use of thin conducting layers. (orig.)
Analysis of formulas used in coupling impedance coaxial-wire measurements for distributed impedances
International Nuclear Information System (INIS)
In this paper the authors study the validity of coupling impedance bench measurements for distributed impedances, comparing the commonly used log formula to the result obtained applying a modified version of Bethe's theory of diffraction to a long slot in a coaxial beam pipe. The equations found provide a quantitative expression for the influence of the wire thickness used in the measurement of the real and imaginary part of the longitudinal impedance. The precision achievable in an actual measurement is therefore discussed. The method presented has also been applied in the presence of lumped impedances
CSR Impedance for Non-Ultrarelativistic Beams
Energy Technology Data Exchange (ETDEWEB)
Li, Rui [Jefferson Lab., Newport News, VA (United States); Tsai, Cheng Y. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Jefferson Lab., Newport News, VA (United States)
2015-09-01
For the analysis of the coherent synchrotron radiation (CSR)-induced microbunching gain in the low energy regime, such as when a high-brightness electron beam is transported through a low-energy merger in an energy-recovery linac (ERL) design, it is necessary to extend the CSR impedance expression in the ultrarelativistic limit to the non-ultrarelativistic regime. This paper presents our analysis of CSR impedance for general beam energies.
Coupling slots without shunt impedance drop
International Nuclear Information System (INIS)
It is well known that coupling slots between adjacent cells in a π-mode structure reduce shunt impedance per unit length with respect to single cell cavities. To design optimized coupling slots, one has to answer the following question: for a given coupling factor, what shape, dimension, position and number of slots lead to the lowest shunt impedance drop? A numerical study using the 3D code MAFIA has been carried out. The aim was to design the 352 MHz cavities for the high intensity proton accelerator of the TRISPAL project. The result is an unexpected set of four 'petal' slots. Such slots should lead to a quasi-negligible drop in shunt impedance: about -1% on average, for particle velocity from 0.4 c to 0.8 c. (author)
Beam impedance measurements on the ALS sector tank
International Nuclear Information System (INIS)
The 10 m long ALS curved sector tank is formed from two shells out of which the beam chamber is machined. Vacuum pumping and photon stops are located in an antechamber connected to the beam tube through a 1cm slot. In order to determine whether the beam is significantly coupled to the antechamber, measurements of longitudinal beam impedance were performed up to 26 GHz, well above the cutoff frequency of the beam pipe. Two different schemes were used: In the first, the wire method was adapted for use above cutoff; in the second, the impedance was detected from the response to TM-waves propagated in the aperture without a wire. Temperature at various locations in the setup was recorded for later phase corrections. Antennas were placed in the antechamber to detect radiated power or possible resonances. A reference measurement was made with the slot sealed by a flexible gasket of knitted wire. The seal was then removed and the response with antechamber recorded. The response was checked by inserting obstacles of known impedance. Both measurement methods provided low numbers with Z/n<0.001 Ohm over the whole frequency range. No resonances attributable to the antechamber were observed. 3 refs., 6 figs
The coupling impedance of the RHIC injection kicker system
International Nuclear Information System (INIS)
In this paper, results from impedance measurements on the RHIC injection kickers are reported. The kicker is configured as a ''C'' cross section magnet with interleaved ferrite and high-permittivity dielectric sections to achieve a travelling wave structure. The impedance was measured using the wire method in which a resistive match provides a smooth transition from the network analyzer to the reference line in the set-up. Accurate results are obtained by interpreting the forward scattering coefficient via the log-formula. The four kickers with their ceramic beam tubes contribute a Z/n=0.22 Ω/ring in the interesting frequency range from 0.1 to 1 GHz, and less above. At frequencies above ∼ 100 MHz, the impedance is ferrite dominated and not affected by the kicker terminations. Below 100 MHz, the Blumlein pulser with the ∼75 m feeding cables is visible in the impedance but makes no significant contribution to the results. The measurements show that the kicker coupling impedance is tolerable without the need for impedance reducing measures
The coupling impedance of the RHIC injection kicker system
International Nuclear Information System (INIS)
In this paper, results from impedance measurements on the RHIC injection kickers are reported. The kicker is configured as a open-quotes Cclose quotes cross section magnet with interleaved ferrite and high-permittivity dielectric sections to achieve a travelling wave structure. The impedance was measured using the wire method in which a resistive match provides a smooth transition from the network analyzer to the reference line in the set-up. Accurate results are obtained by interpreting the forward scattering coefficient via the log-formula. The four kickers with their ceramic beam tubes contribute a Z/n = 0.22 Ω/ring in the interesting frequency range from 0.1 to 1 GHz, and less above. At frequencies above ∼100 MHZ, the impedance is ferrite dominated and not affected by the kicker terminations. Below 100 MHz, the Blumlein pulser with the ∼75 m feeding cables is visible in the impedance but makes no significant contribution to the results. The measurements show that the kicker coupling impedance is tolerable without the need for impedance reducing measures
Coupled Transmission Lines as Impedance Transformer
DEFF Research Database (Denmark)
Jensen, Thomas; Zhurbenko, Vitaliy; Krozer, Viktor;
2007-01-01
A theoretical investigation of the use of a coupled line section as an impedance transformer is presented. We show how to properly select the terminations of the coupled line structures for effective matching of real and complex loads in both narrow and wide frequency ranges. The corresponding...... circuit configurations and the design procedures are proposed. Synthesis relations are derived and provided for efficient matching circuit construction. Design examples are given to demonstrate the flexibility and limitations of the design methods and to show their validity for practical applications....... Wideband matching performance with relative bandwidth beyond 100% and return loss > 20 dB is demonstrated both theoretically and experimentally. Good agreement is achieved between the measured and predicted performance of the coupled line transformer section....
Estimate of the coupling impedance for the storage rings of the NSLS
International Nuclear Information System (INIS)
The most important ingredient to evaluate the stability of a particle beam in a storage ring is the longitudinal coupling impedance Z/n and the transverse impedance Z/sub perpendicular to/ which is usually associated to the former. These impedances are calculated for the two storage rings which are part of the NSLS, namely the Ultra Violet Ring (UVR) and the x-Ray Ring
Coupling impedance of a periodic array of diaphragms
International Nuclear Information System (INIS)
A method is presented for calculating the high-frequency longitudinal and transverse coupling impedances in a periodic array of diaphragms in a circular perfectly conducting pipe. The method is based on Weinstein's theory of diffraction of a plane electromagnetic wave on a stack of halfplanes. Using Weinstein's solution, it is shown that the problem of finding the beam field in the pipe reduces to an effective boundary condition at the radius of the diaphragms that couples the longitudinal electric field with the azimuthal magnetic one. Solving Maxwell's equations with this boundary condition leads to simple formulae for Zlong and Ztr. A good agreement with a numerical solution of the problem found by other authors is demonstrated
A new method for calculation of low-frequency coupling impedance
International Nuclear Information System (INIS)
In high-energy proton accelerators and storage rings the bunch length is typically at least a few times larger than the radius of the vacuum chamber. For example, the SSC will have an rms bunch length above 6 cm and a beam-pipe radius below 2 cm. The main concern for beam stability in such a machine is the low-frequency impedance, i.e., the coupling impedance at frequencies wen below the cut-off frequency of the vacuum chamber. In the present paper we develop a new analytical approach for calculation of the low-frequency impedance of axisymmetric structures that allows us to give quick and reliable estimates of contributions to the impedance from various chamber discontinuities. Simple formulae for the longitudinal impedance of some typical discontinuities are obtained
A new method for calculation of low-frequency coupling impedance
Energy Technology Data Exchange (ETDEWEB)
Kurennoy, S.S.; Stupakov, G.V.
1993-05-01
In high-energy proton accelerators and storage rings the bunch length is typically at least a few times larger than the radius of the vacuum chamber. For example, the SSC will have an rms bunch length above 6 cm and a beam-pipe radius below 2 cm. The main concern for beam stability in such a machine is the low-frequency impedance, i.e., the coupling impedance at frequencies wen below the cut-off frequency of the vacuum chamber. In the present paper we develop a new analytical approach for calculation of the low-frequency impedance of axisymmetric structures that allows us to give quick and reliable estimates of contributions to the impedance from various chamber discontinuities. Simple formulae for the longitudinal impedance of some typical discontinuities are obtained.
Acoustic impedances of audiometric earphones coupled to different loads
DEFF Research Database (Denmark)
Ciric, Dejan; Hammershøi, Dorte
The acoustic impedance of an audiometric earphone is one of the factors that can affect sound transmission through the ear during tests of hearing sensitivity. Similar situation exists during calibration of the earphone where its impedance can affect sound transmission through a coupler. The...... importance of this impedance is related to the contribution of other elements involved in transmission such as ear canal impedance or impedance of the coupler seen from outside. In order to determine the acoustic impedances of five audiometric earphones, the standardized method for measurement of complex......, audiometric earphones are coupled to different loads. Thus, they are placed on different terminations of the tube including metal plate, artificial rubber pinna and upper part of the standardized coupler. The results show that the impedances of earphones are different, but they also differ from radiation...
Coupling impedance of vacuum pumping holes for the APS storage ring
International Nuclear Information System (INIS)
The coupling impedance of a single slot in a thick wall beam pipe was measured. The slot dimension is small compared to the wavelength of interest. The measurements were done by the wire method with the synthetic pulse technique. Gating technique was also applied to obtain the reflection response for a structure that does not have appropriate calibration standards. The measured results are in good agreement with calculated impedance using analytical formulae given by other authors
MEASURED TRANSVERSE COUPLING IMPEDANCE OF RHIC INJECTION AND ABORT KICKERS
International Nuclear Information System (INIS)
Concerns regarding possible transverse instabilities in RHIC and the SNS pointed to the need for measurements of the transverse coupling impedance of ring components. The impedance of the RHIC injection and abort kicker was measured using the conventional method based on the S21 forward transmission coefficient. A commercial 450 Ω twin-wire Lecher line were used and the data was interpreted via the log-formula. All measurements, were performed in test stands fully representing operational conditions including pulsed power supplies and connecting cables. The measured values for the transverse coupling impedance in kick direction and perpendicular to it are comparable in magnitude, but differ from Handbook predictions
The concept of coupling impedance in the self-consistent plasma wake field excitation
Fedele, R.; Akhter, T.; De Nicola, S.; Migliorati, M.; Marocchino, A.; Massimo, F.; Palumbo, L.
2016-09-01
Within the framework of the Vlasov-Maxwell system of equations, we describe the self-consistent interaction of a relativistic charged-particle beam with the surroundings while propagating through a plasma-based acceleration device. This is done in terms of the concept of coupling (longitudinal) impedance in full analogy with the conventional accelerators. It is shown that also here the coupling impedance is a very useful tool for the Nyquist-type stability analysis. Examples of specific physical situations are finally illustrated.
Magnetically coupled impedance-source inverters
DEFF Research Database (Denmark)
Loh, Poh Chiang; Blaabjerg, Frede
2012-01-01
magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters. Most of which are linked to their requirement for low modulation ratio at high....... The same methodology is then applied to develop more magnetically coupled Z-source inverters with advantages that have not been identified in the literature. These findings have already been proven in experiments....
Magnetically Coupled Impedance-Source Inverters
DEFF Research Database (Denmark)
Loh, Poh Chiang; Blaabjerg, Frede
2013-01-01
magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters, most of which are linked to their requirement for low modulation ratio at high....... The same methodology is then applied to develop more magnetically coupled Z-source inverters with advantages that have not been identified in the literature. These findings have already been proven in experiments....
THE COUPLING IMPEDANCE OF THE RHIC INJECTION KICKER SYSTEM
International Nuclear Information System (INIS)
IN THIS PAPER, RESULTS FROM IMPEDANCE MEASUREMENTS ON THE RHIC INJECTION KICKERS ARE REPORTED. THE KICKER IS CONFIGURED AS A ''C'' CROSS SECTION MAGNET WITH INTERLEAVED FERRITE AND HIGH-PERMITTIVITY DIELECTRIC SECTIONS TO ACHIEVE A TRAVELLING WAVE STRUCTURE. THE IMPEDANCE WAS MEASURED USING THE WIRE METHOD, AND ACCURATE RESULTS ARE OBTAINED BY INTERPRETING THE FORWARD SCATTERING COEFFICIENT VIA THE LONG-FORMULA. THE FOUR KICKERS WITH THEIR CERAMIC BEAM TUBES CONTRIBUE AT Z/N-0.22 OMEGA/RING IN THE INTERESTING FREQUENCY RANGE FROM 0.1 TO 1 BHZ, AND LESS ABOVE
Calculation of the coupling impedances of holes and slots on the liner using MAFIA and scaling
Energy Technology Data Exchange (ETDEWEB)
Thiagarajan, V.; Barts, T.; Kurennoy, S.; Chou, W.
1993-11-01
The location of a liner inside the beam tube is one of the options considered for the Super Colliders. The liner could serve as a synchrotron radiation intercept and also help enhance the vacuum. A definite distribution of holes or slots is required to be located on the liner for pumping out the desorbing gases. There will be wake fields propagating within the liner due to diffraction at discontinuities following the incident beam fields. The effect of these wake fields can be minimized by adopting the least number of pumping holes/slots required and through an optimal choice of hole/slot shape and size. The effect of the wake fields on the beam may be expressed through coupling impedances defined proportional to the corresponding forces integrated through distance per unit charge. It is necessary to compute the impedance of holes and slots and determine the scaling of the impedance with the dimensions of the hole/slot and the liner, in order to optimize the choice of pumping holes/slots. The coupling impedances of slots and holes have been calculated here using the code MAFIA and the scaling assessed. The results compare favorably with existing analytical results.
Matrix solution of coupling impedance in multi-layer circular cylindrical structures
International Nuclear Information System (INIS)
Continuing interest in computing the coupling impedance of cylindrical multi-layer beam tubes led to several recent publications. A novel matrix method is here presented in which radial wave propagation is treated in analogy to longitudinal transmission lines. Starting from the Maxwell equations the solutions for monopole electromagnetic fields are in each layer described by a 2 x 2 matrix. Assuming isotropic material properties within one layer, the radially transverse field components at the inner boundary of a layer are uniquely determined by matrix transfer of the field components at its outer boundary. By imposing power flow constraints on the matrix, field matching between layers is enforced and replaced by matrix multiplication. The coupling impedance of a stainless steel beam tube defined by a matrix is given as a representative demonstration
Matrix solution of coupling impedance in multi-layer circular cyclindrical structures
Energy Technology Data Exchange (ETDEWEB)
Hahn,H.; Choi, E.
2009-05-04
Continuing interest in computing the coupling impedance of cylindrical multi-layer beam tubes led to several recent publications. A novel matrix method is here presented in which radial wave propagation is treated in analogy to longitudinal transmission lines. Starting from the Maxwell equations the solutions for monopole electromagnetic fields are in each layer described by a 2 x 2 matrix. Assuming isotropic material properties within one layer, the radially transverse field components at the inner boundary of a layer are uniquely determined by matrix transfer of the field components at its outer boundary. By imposing power flow constraints on the matrix, field matching between layers is enforced and replaced by matrix multiplication. The coupling impedance of a stainless steel beam tube defined by a matrix is given as a representative demonstration.
Design study of a movable mask with low beam impedance
International Nuclear Information System (INIS)
A novel design of a movable-mask (collimator) for high current accelerators is proposed. The mask head is supported by a ceramics rod to reduce the interference with beam. One side of the rod is coated by a thin conductive material to avoid charge up of the head. The head is made of graphite or ceramics coated with copper to avoid the direct damage by an intense beam. The impedances of trapped modes, the loss factors and so on were evaluated by simulation codes. The frequencies and the Q factors of the trapped modes were also measured using a cold model, and compared with calculated ones. (author)
Bench measurements of coupling impedance of AGS Booster components
International Nuclear Information System (INIS)
Quantifying instability thresholds for modern synchrotrons and storage rings requires some knowledge of the accelerator's coupling impedance. To this end, the wire technique has been implemented to measure the longitudinal coupling impedance of AGS Booster devices. The techniques are being refined to allow measurement of RHIC devices at higher frequencies. All the measurements are performed using an HP 8753 Network Analyzer controlled via GPIB by a Macintosh computer. The computer provides an environment for automated data acquisition, data analysis, and report generation. Resistive matches between the 50ω analyzer cables and the 300ω pipe-and-wire structure allow the use of a simple response calibration in the measurement of S21 to 400MHz. Results from ferrite loaded rf cavities, position monitors and kickers are presented. 4 refs., 4 figs
International Nuclear Information System (INIS)
Good electron beam qualities and stability are the crucial features of Storage Rings dedicated to synchrotron radiation sources or to Free Electron Laser. Most of these characteristics depends on the coupling of the e-beam with the machine environment, which can be in turn modelled in terms of a characteristic impedance, whose absolute value and structure can be used to specify both the stability (longitudinal and transverse) of the beam and its qualities (energy spread, bunch length, peak current ...). In this paper are considered two specific examples of Storage Rings used for FEL operation and analyze their performances by means of semi analytical and numerical methods. The analysis is aimed at clarifying the dependence of beam energy spread and bunch length on beam current and at providing a set of parameters useful for the optimization of Free Electron Laser or synchrotron radiation sources
Beam steering and impedance matching of plasmonic horn nanoantennas
Afridi, Adeel
2016-01-01
In this paper, we study a plasmonic horn nanoantenna on a metal-backed substrate. The horn nanoantenna structure consists of a two-wire transmission line (TWTL) flared at the end. We analyze the effect of the substrate thickness on the nanoantenna's radiation pattern, and demonstrate beam steering in a broad range of elevation angles. Furthermore, we analyze the effect of the ground plane on the impedance matching between the antenna and the TWTL, and observe that the ground plane increases the back reflection into the waveguide. To reduce the reflection, we develop a transmission line model to design an impedance matching section which leads to 99.75% power transmission to the nanoantenna.
Measurement of the longitudinal coupling impedance in the Brookhaven AGS
International Nuclear Information System (INIS)
The imaginary part of the longitudinal coupling impedance has been measured as a function of energy from 5 to approx. 28 GeV. This impedance is proportional to Δf = (f/sub q/--2f/sub d/) where f/sub d/ is the coherent dipole frequency and f/sub q/ the coherent quadrupole frequency. These frequencies are obtained by stimulating coupled bunch oscillations. If the dominant impedance is due to inductive wall plus space charge effects, then one has (Z/n) = j[Ω0L--g0Z0/2BETAγ.2]1 where L is the inductance per turn and Ω0 = 2πf0 the particle rotation frequency. The expression (Z/n) = 4jΔfπ2hV0cos phi/sub s/B3/3I0f/sub d/ can be used to find the impedance if the synchrotron phase space distribution is proportional to (1--r2)/sub 1/2/. I0 is the current per bunch, B = f0 x tau0 the bunch length and V0 is the external voltage. For a distribution given by (1--r2) the right hand side should be multiplied by 27/4π2. If the latter is assumed, an inductive impedance of 20.4 Ω is obtained with a null at approx. = 6 Gev (γ/sub tr/ = 8.5) for a transverse emittance of 22 πμ rad-m. At 5 GeV the reactance is negative but larger than the simple relation assumed for (Z/n) would predict. If the bunches are parabolic, then the inductive impedance would be 29.7 Ω with a null again at 6.6 GeV but only for an emittance of 2.5 μrad-m. Again the 5 GeV reactance is much too large. The significance of these results is discussed
Coupled Lines Filters for Broadband Impedance Matching of Microwave Amplifiers
Directory of Open Access Journals (Sweden)
Mohammed Lahsaini
2014-08-01
Full Text Available In this paper we present a broadband matching technique for the design of low noise amplifiers. This technique is based on the use of coupled lines filters and quarter wave transformers for the adaptation and stabilization of these amplifiers, presenting the theory and the design process of these circuits. The type of transistors used for modeling this amplifier is the HEMT of Alpha Industries®. The results we found show that this amplifier is unconditionally stable with a satisfactory gain of about 20 dB and good impedance matching across the band of interest [10-12] GHz. The amplifier modeled in this work can be integrated in satellite receiving systems and radar systems.
Directory of Open Access Journals (Sweden)
Hon Tat Hui
2010-01-01
Full Text Available A short review of the receiving-mutual-impedance method (RMIM for mutual coupling compensation in direction finding applications using linear array is conducted. The differences between the conventional-mutual-impedance method (CMIM and RMIM, as well as the three different determination methods for receiving mutual impedance (RMI, will be discussed in details. As an example, direction finding with better accuracies is used for demonstrating the superiority of mutual coupling compensation using RMIM.
Hon Tat Hui; Hoi Shun Lui
2010-01-01
A short review of the receiving-mutual-impedance method (RMIM) for mutual coupling compensation in direction finding applications using linear array is conducted. The differences between the conventional-mutual-impedance method (CMIM) and RMIM, as well as the three different determination methods for receiving mutual impedance (RMI), will be discussed in details. As an example, direction finding with better accuracies is used for demonstrating the superiority of mutual coupling compensation u...
Small Signal Modeling and Comprehensive Analysis of Magnetically Coupled Impedance Source Converters
DEFF Research Database (Denmark)
Forouzesh, Mojtaba; Siwakoti, Yam Prasad; Blaabjerg, Frede;
2016-01-01
Magnetically coupled impedance-source (MCIS) networks are recently introduced impedance networks intended for various high-boost applications. It employs coupled magnetic in the circuit to achieve higher voltage gain. Various MCIS networks have been proposed in the literature for myriad applicati...
Effects of leakage inductances on magnetically-coupled impedance-source networks
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Loh, Poh Chiang; Blaabjerg, Frede;
2014-01-01
Coupled inductors have lately been used with impedance-source networks for keeping their shoot-through times short, while providing higher voltage boosts. The parameter that is critical to the operation of such impedance network based converter with coupled inductors is the leakage inductances. H...
Energy Technology Data Exchange (ETDEWEB)
Petracca, S. [Salerno Univ. (Italy)
1996-08-01
Debye potentials, the Lorentz reciprocity theorem, and (extended) Leontovich boundary conditions can be used to obtain simple and accurate analytic estimates of the longitudinal and transverse coupling impedances of (piecewise longitudinally uniform) multi-layered pipes with non simple transverse geometry and/or (spatially inhomogeneous) boundary conditions. (author)
Ultrafast Beam Switching Using Coupled VCSELs
Ning, Cun-Zheng; Goorjian, Peter
2001-01-01
We propose a new approach to performing ultrafast beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The strategy is demonstrated by numerical simulation, showing a beam switching of 10 deg at 42 GHz.
Coupled-Beam and Coupled-Bunch Instabilities
Burov, Alexey
2016-01-01
A problem of coupled-beam instability is solved for two multibunch beams with slightly different revolution frequencies, as in the Fermilab Recycler Ring (RR). Sharing of the inter-bunch growth rates between the intra-bunch modes is described. The general analysis is applied to the RR; possibilities to stabilize the beams by means of chromaticity, feedback and Landau damping are considered.
Impedance-based analysis and study of phase sensitivity in slow-wave two-beam accelerators
International Nuclear Information System (INIS)
This paper presents a new formalism which makes the analysis and understanding of both the relativistic klystron (RK) and the standing-wave free-electron laser (SWFEL) two-beam accelerator (TBA) available to a wide audience of accelerator physicists. A ''coupling impedance'' for both the RK and SWFEWL is introduced, which can include realistic cavity features, such as beam and vacuum ports, in a simple manner. The RK and SWFEL macroparticle equations, which govern the energy and phase evolution of successive bunches in the beam, are of identical form, differing only by multiplicative factors. Expressions are derived for the phase and amplitude sensitivities of the TBA schemes to errors (shot-to-shot jitter) in current and energy. The analysis allows, for the first time, relative comparisons of the RK and the SWFEL TBAs
Energy Technology Data Exchange (ETDEWEB)
Dattoli, G.; Mezi, L.; Renieri, A. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Frascati, RM (Italy); Migliorati, M. [Rome Univ. La Sapienza, Rome (Italy). Dipt. di Energetica; Couprie, M.E.; Garzella, D.; Nutarelli, D.; Thomas, C.; De Ninno, G. [Service de Photons, Atomes et Molecules DSM/DRECAM, Gif Sur Yvette (France); Walker, R. [Sincrotrone, Basorizza, TS (Italy)
2000-07-01
Good electron beam qualities and stability are the crucial features of Storage Rings dedicated to synchrotron radiation sources or to Free Electron Laser. Most of these characteristics depends on the coupling of the e-beam with the machine environment, which can be in turn modelled in terms of a characteristic impedance, whose absolute value and structure can be used to specify both the stability (longitudinal and transverse) of the beam and its qualities (energy spread, bunch length, peak current ...). In this paper are considered two specific examples of Storage Rings used for FEL operation and analyze their performances by means of semi analytical and numerical methods. The analysis is aimed at clarifying the dependence of beam energy spread and bunch length on beam current and at providing a set of parameters useful for the optimization of Free Electron Laser or synchrotron radiation sources. [Italian] La qualita' di fascio di un anello di accumulazione e la sua stabilita' sono le caratteristiche cruciali di un anello di accumulazione dedicato a sorgenti di Luce di Sincrotrone o al Laser ad Elettroni Liberi. La gran parte di tali caratteristiche dipende dall'accoppiamento del fascio di elettroni con la macchina stessa, tale accoppiamento puo' essere descritto in termini di una impedenza caratteristica, il cui valore assoluto e struttura possono essere utilizzati per specificarne sia la stabilita' del fascio (longitudinale e trasversale) e le sue qualita' (dispersione di energia, lunghezza del pacchetto, corrente di picco ...). In questo articolo si considerano due esempi specifici di anelli di accumulazione utilizzati per l'operazione Laser ed Elettroni Liberi e si analizzano le loro caratteristiche per mezzo di metodi semianalitici e numerici. L'analisi e' essenzialmente dedicata a chiarire la dipendenza della dispersione di energia e della lunghezza del pacchetto dalla corrente media e a fornire un insieme di
Coupling of impedance functions to nuclear reactor building for soil-structure interaction analysis
International Nuclear Information System (INIS)
Finite element model of a nuclear reactor building is coupled to complex soil impedance functions and soil-structure-interaction analysis is carried out in frequency domain. In the second type of analysis applied in this paper, soil impedance functions are used to evaluate equivalent soil springs and dashpots of soil. These are coupled to the structure model in order to carry out the time marching analysis. Three types of soil profiles are considered: hard, medium and soft. Results of two analyzes are compared on the same structural model. Equivalent soil springs and dashpots are determined using new method based on the least square approximation. (author)
Effect of the Various Impedances on Longitudinal Beam Stability in the CERN SPS
Lasheen, Alexandre; Repond, Joël; Shaposhnikova, Elena
2016-01-01
The High Luminosity (HL)-LHC project at CERN aims at a luminosity increase by a factor ten and one of the necessary ingredients is doubling the bunch intensity to 2.4x10¹¹ ppb for beams with 25 ns bunch spacing. Many improvements are already foreseen in the frame of the LHC Injector Upgrade (LIU) project, but probably this intensity would still not be reachable in the SPS due to longitudinal instabilities. Recently a lot of effort went into finding the impedance sources of the instabilities. Particle simulations based on the latest SPS impedance model are now able to reproduce the measured instability thresholds and were used to determine the most critical impedance sources by removing them one by one from the model. It was found that impedance of vacuum flanges and of the already damped 630 MHz HOM of the main RF system gave for 72 bunches the comparable intensity thresholds. Possible intensity gains are defined for realistic impedance modifications and for various beam configurations (number of bunches, l...
Mounet, N
2010-01-01
Using B. Zotter’s formalism, we present here a novel, efficient and exact matrix method for the field matching determination of the electromagnetic field components created by an offset point charge travelling at any speed in an infinitely long circular multilayer beam pipe. This method improves by a factor of more than one hundred the computational time with three layers and allows the computation for more layers than three. We also generalize our analysis to any azimuthal mode and finally perform the summation on all such modes in the impedance formulae. In particular the exact multimode direct space-charge impedances (both longitudinal and transverse) are given, as well as the wall impedance to any order of precision.
Ultrafast Directional Beam Switching in Coupled VCSELs
Ning, Cun-Zheng; Goorjian, Peter
2001-01-01
We propose a new approach to performing ultrafast directional beam switching using two coupled Vertical-Cavity Surface-Emitting Lasers (VCSELs). The proposed strategy is demonstrated for two VCSELs of 5.6 microns in diameter placed about 1 micron apart from the edges, showing a switching speed of 42 GHz with a maximum far-field angle span of about 10 degrees.
International Nuclear Information System (INIS)
In future B-factories, many bunches will be circulated in their rings, and thus making the bunch spacing to become very short compared with that of the present collider machines. The impedance of the rings may cause many coupled bunch beam oscillations. One possibility to damp these multi-bunch oscillations is to install an active oscillation feedback damper system. This paper discusses the transverse feedback system. (author)
A method of phase control and impedance matching of mutually coupled ICRF antennas in LHD
International Nuclear Information System (INIS)
In the Large Helical Device (LHD), the installation of a pair of ion cyclotron range of frequencies (ICRF) antennas from upper and lower ports is planned. These antennas are geometrically symmetrical and located side by side. By changing the current phase on the straps, the wave number parallel to the magnetic field line can be controlled. However, antenna impedances will also be changed and reflected power will increase due to mutual coupling. For efficient power injection and the protection of tetrode tubes, the parameters of impedance matching devices must be controlled together with the current phase. A method was formulated and trials of phase control and impedance matching were successfully conducted with a simplified two-port dummy antenna. (author)
Low-impedance plasma systems for generation of high-current low-energy electron beams
Agafonov, A. V.
2006-12-01
The results of experimental investigation and numerical modeling of the generation of low-energy (tens of keV) high-current (up to tens of kA) electron beams in a low-impedance system consisting of a plasma-filled diode with a long plasma anode, an auxiliary hot cathode, and an explosive emission cathode. The low-current low-voltage beam from the auxiliary cathode in an external longitudinal magnetic field is used to produce a long plasma anode, which is simultaneously the channel of beam transportation by residual gas ionization. The high-current electron beam is formed from the explosive emission cathode placed in the preliminarily formed plasma. Numerical modeling is performed using the KARAT PIC code.
A wide band slot-coupled beam sensing electrode for the Advanced Light Source (ALS)
International Nuclear Information System (INIS)
Stripline electrodes (traveling wave electrodes, directional couplers) are commonly used in particle accelerators as beam pickups and kickers. The longitudinally symmetric stripline has a constant beam coupling impedance as a function of length and has a characteristic magnitude sin(x) amplitude response in the frequency domain. An exponentially tapered stripline provides nearly constant coupling impedance vs. frequency and yields superior frequency-domain performance. In practice it is difficult to construct either of these devices for broad-band performance because of the transition from coaxial to stripline geometry. The authors report on the construction of an exponentially-tapered, slot-coupled 'stripline' which was relatively easy to construct and has the desired frequency response
DEFF Research Database (Denmark)
Zhurbenko, Vitaliy; Krozer, Viktor; Meincke, Peter
2007-01-01
A new broadband quarter-wavelength impedance transformer based on an asymmetric coupled line section is presented. The bandwidth of the coupled line transformer is extended with the help of an interconnecting transmission line. An analytical model for the transformer is developed. The analysis of...... the structure reveals that a fractional bandwidth of more than 100% at –20 dB reflection level can be achieved with such a structure. An experimental transformer circuit has been designed, fabricated and tested. Theoretical and experimental results are fair agreement and confirm the established theory....... The achieved bandwidth is almost 3 times larger as compared with standard matching circuits....
Mechanical and electrical impedance matching in a piezoelectric beam for Energy Harvesting
Koszewnik, A.; Grześ, P.; Walendziuk, W.
2015-11-01
A piezoelectric beam is one of transducers for energy harvesting. It provides easy implementation and good performance in changing mechanical stress into electric voltage. In order to maximize output power, it is important to provide mechanical and electrical impedance matching. In the paper the authors proposed a methodology which allows to find values of lumped elements in an electromechanical model after completing appropriate measurements. Due to linear equations, it is possible to model a beam in both mechanical and electrical ways, and match the best load depending of frequency. The proposed model of a piezoelectric cantilever shows a potential use of these devices in micro scale as a cantilever which is a part of a silicon structure. Moreover, in the paper, the authors discuss mechanical aspects of using a weight as the way to tune the piezoelectric beam to a specific frequency. The electrical aspect of matching the source impedance with load, which is based on an electrical model of a piezoelectric transducer, is also presented. In the paper a mathematical model was verified by an experiment in which a laboratory stand equipped with a vibration generator, a piezoelectric energy harvester and acceleration sensors was used.
Development of a low impedance electron-beam system for high power excimer laser excitation
International Nuclear Information System (INIS)
Two modules of a low impedance electron-beam machine have been developed to pump a 200 J, 70 ns KrF laser. The laser is designed as the final amplifier of a tera-watt level picosecond excimer laser system. The operating characteristics of this device have been studied. The energy deposited in the 42 litter laser gain region is measured by several different diagnostics to be 3 kJ with good spatial uniformity. The triggered operation of the 500 kV main rail switch, which is essential for system synchronization, has been demonstrated by the UV laser irradiation along the rail gap axis
DEFF Research Database (Denmark)
Lei, Anders; Xu, R.; Borregaard, L. M.;
2014-01-01
The single degree of freedom mass-spring-damper system is the most common approach for deriving a full electromechanical model for the piezoelectric vibration energy harvester. In this paper, we revisit this standard electromechanical model by focusing on the impedance of the piezoelectric device...... remaining parameter is determined from shaker measurements, and a highly accurate agreement is found between model and measurements on a unimorph MEMS-based screen printed PZT harvester. With a high coupling term K-2 Q similar or equal to 7, the harvester exhibits two optimum load points. The peak power...
Thermal Impedance Model of High Power IGBT Modules Considering Heat Coupling Effects
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
2014-01-01
Thermal loading of Insulated Gate Bipolar Transistor (IGBT) modules is important for the reliability performance of power electronic systems, thus the thermal information of critical points inside module like junction temperature must be accurately modeled and predicted. Usually in the existing...... thermal models, only the self-heating effects of the chips are taken into account, while the thermal coupling effects among chips are less considered. This could result in inaccurate temperature estimation, especially in the high power IGBT modules where the chips are allocated closely to each other with...... large amount of heat generated. In this paper, both the self-heating and heat-coupling effects in the of IGBT module are investigated based on Finite Element Method (FEM) simulation, a new thermal impedance model is thereby proposed to better describe the temperature distribution inside IGBT modules. It...
Electromagnetic scattering of a vector Bessel beam in the presence of an impedance cone
Salem, Mohamed
2013-07-01
The electromagnetic field scattering of a vector Bessel beam in the presence of an infinite circular cone with an impedance boundary on its surface is considered. The impinging field is normal to the tip of the cone and is expanded in terms of vector spherical wave functions; a Kontorovich-Lebedev (KL) transform is employed to expand the scattered fields. The problem is reduced to a singular integral equation with a variable coefficient of the non-convolution type. The singularities of the spectral function are deduced and representations for the field at the tip of the cone as well as other regions are given together with the conditions of validity of these representations. © 2013 IEEE.
Surface Impedance Formalism for a Metallic Beam Pipe with Small Corrugations
Energy Technology Data Exchange (ETDEWEB)
Stupakov, G.; Bane, K.L.F.; /SLAC
2012-08-30
A metallic pipe with wall corrugations is of special interest in light of recent proposals to use such a pipe for the generation of terahertz radiation and for energy dechirping of electron bunches in free electron lasers. In this paper we calculate the surface impedance of a corrugated metal wall and show that it can be reduced to that of a thin layer with dielectric constant {epsilon} and magnetic permeability {mu}. We develop a technique for the calculation of these constants, given the geometrical parameters of the corrugations. We then calculate, for the specific case of a round metallic pipe with small corrugations, the frequency and strength of the resonant mode excited by a relativistic beam. Our analytical results are compared with numerical simulations, and are shown to agree well.
Hynynen, Kullervo; Yin, Jianhua
2009-01-01
A method that uses lateral coupling to reduce the electrical impedance of small transducer elements in generating ultrasound waves was tested. Cylindrical, radially-polled transducer elements were driven at their length resonance frequency. Computer simulation and experimental studies showed that the electrical impedance of the transducer element could be controlled by the cylinder wall thickness, while the operation frequency was determined by the cylinder length. Acoustic intensity (average...
Pumping slots: impedances and power losses
Energy Technology Data Exchange (ETDEWEB)
Kurennoy, S. [Maryland Univ., College Park, MD (United States). Dept. of Physics
1996-08-01
Contributions of pumping slots to the beam coupling impedances and power losses in a B-factory ring are considered. While their leading contribution is to the inductive impedance, for high-intensity machines with short bunches like e{sup +}e{sup -} B-factories the real part of the impedance and related loss factors are also important. Using an analytical approach we calculate the coupling impedances and loss factors due to slots in a ring with an arbitrary cross section of the vacuum chamber. Effects of the slot tilt on the beam impedance are also considered, and restrictions on the tilt angle are derived from limitations on the impedance increase. The power leakage through the slots is discussed briefly. The results are applied to the KEK B-factory. (author)
Energy Technology Data Exchange (ETDEWEB)
Bettini, Luca Giacomo; Bardizza, Giorgio; Podesta, Alessandro; Milani, Paolo; Piseri, Paolo, E-mail: piseri@mi.infn.it [Universita degli Studi di Milano, Dipartimento di Fisica and CIMaINa (Italy)
2013-02-15
Nanostructured porous films of carbon with density of about 0.5 g/cm{sup 3} and 200 nm thickness were deposited at room temperature by supersonic cluster beam deposition (SCBD) from carbon clusters formed in the gas phase. Carbon film surface topography, determined by atomic force microscopy, reveals a surface roughness of 16 nm and a granular morphology arising from the low kinetic energy ballistic deposition regime. The material is characterized by a highly disordered carbon structure with predominant sp2 hybridization as evidenced by Raman spectroscopy. The interface properties of nanostructured carbon electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy employing KOH 1 M solution as aqueous electrolyte. An increase of the double layer capacitance is observed when the electrodes are heat treated in air or when a nanostructured nickel layer deposited by SCBD on top of a sputter deposited film of the same metal is employed as a current collector instead of a plain metallic film. This enhancement is consistent with an improved charge injection in the active material and is ascribed to the modification of the electrical contact at the interface between the carbon and the metal current collector. Specific capacitance values up to 120 F/g have been measured for the electrodes with nanostructured metal/carbon interface.
A motion-compensated cone-beam CT using electrical impedance tomography imaging
International Nuclear Information System (INIS)
Cone-beam CT (CBCT) is an imaging technique used in conjunction with radiation therapy. For example CBCT is used to verify the position of lung cancer tumours just prior to radiation treatment. The accuracy of the radiation treatment of thoracic and upper abdominal structures is heavily affected by respiratory movement. Such movement typically blurs the CBCT reconstruction and ideally should be removed. Hence motion-compensated CBCT has recently been researched for correcting image artefacts due to breathing motion. This paper presents a new dual-modality approach where CBCT is aided by using electrical impedance tomography (EIT) for motion compensation. EIT can generate images of contrasts in electrical properties. The main advantage of using EIT is its high temporal resolution. In this paper motion information is extracted from EIT images and incorporated directly in the CBCT reconstruction. In this study synthetic moving data are generated using simulated and experimental phantoms. The paper demonstrates that image blur, created as a result of motion, can be reduced through motion compensation with EIT
Beam envelope calculations in general linear coupled lattices
Energy Technology Data Exchange (ETDEWEB)
Chung, Moses, E-mail: mchung@unist.ac.kr [Department of Physics, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Qin, Hong [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Groening, Lars; Xiao, Chen [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt (Germany); Davidson, Ronald C. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)
2015-01-15
The envelope equations and Twiss parameters (β and α) provide important bases for uncoupled linear beam dynamics. For sophisticated beam manipulations, however, coupling elements between two transverse planes are intentionally introduced. The recently developed generalized Courant-Snyder theory offers an effective way of describing the linear beam dynamics in such coupled systems with a remarkably similar mathematical structure to the original Courant-Snyder theory. In this work, we present numerical solutions to the symmetrized matrix envelope equation for β which removes the gauge freedom in the matrix envelope equation for w. Furthermore, we construct the transfer and beam matrices in terms of the generalized Twiss parameters, which enables calculation of the beam envelopes in arbitrary linear coupled systems.
Stopping Power for Strong Beam-Plasma Coupling
Gericke, Dirk O.
2001-10-01
The slowing down process of charged particles in plasma targets is investigated for the case of strong beam-plasma coupling. Strong beam-plasma correlations can be considered using the collision operator of the quantum Boltzmann equation. As a first step, dynamic screening is included in the first Born approximation. This approach gives good results for moderate beam-plasma coupling (Zb Γ^3/2 Bethe-formula, the standard model of the stopping power (Bethe plus Bloch corrections and Barkas terms), the Li & Petrasso formula and simulation data (MD and PIC), is given. This comparison clearly shows the advantage of the proposed model: it smoothly interpolates between the classical low velocity regime, where strong coupling effects occur, and the high velocity quantum regime, where collective modes are important. In the latter case, the experimentally proven Bethe-formula is obtained. Furthermore, it matches the simulation data for moderate as well as strong beam-plasma coupling.
Proceedings of the impedance and bunch instability workshop
Energy Technology Data Exchange (ETDEWEB)
1990-04-01
This report discusses the following topics: impedance and bunch lengthening; single bunch stability in the ESRF; a longitudinal mode-coupling instability model for bunch lengthening; high-frequency behavior of longitudinal coupling impedance; beam-induced energy spreads at beam-pipe transitions; on the calculation of wake functions using MAFIA-T3 code; preliminary measurements of the bunch length and the impedance of LEP; measurements and simulations of collective effects in the CERN SPS; bunch lengthening in the SLC damping rings; and status of impedance measurements for the spring-8 storage ring.
Proceedings of the impedance and bunch instability workshop
International Nuclear Information System (INIS)
This report discusses the following topics: impedance and bunch lengthening; single bunch stability in the ESRF; a longitudinal mode-coupling instability model for bunch lengthening; high-frequency behavior of longitudinal coupling impedance; beam-induced energy spreads at beam-pipe transitions; on the calculation of wake functions using MAFIA-T3 code; preliminary measurements of the bunch length and the impedance of LEP; measurements and simulations of collective effects in the CERN SPS; bunch lengthening in the SLC damping rings; and status of impedance measurements for the spring-8 storage ring
A Physical Description of the Response of Coupled Beams
DEFF Research Database (Denmark)
Hugin, Claus Thomas
1997-01-01
An analytical method is presented for computing the vibrational response and the net transmitted power of bending wave fields in system consisting of coupled finite beams. The method is based on a wave approach that utilises the reflection and transmission coefficients of the different beam joints...
Directory of Open Access Journals (Sweden)
Milan Svanda
2014-01-01
Full Text Available The recently introduced coupled shorted-patches technique for the design of extremely low-profile UHF RFID tag antennas is used to illustrate the flexibility of selected feeding methods for tuning the antenna input impedance for the complex values required for matching with typical RFID chips. We present parametric studies of the impedance behaviour of dipole-excited and directly excited antennas designed for radiofrequency identification of people in the European UHF frequency band. Our study can significantly facilitate the design of this class of on-body tag antennas.
Transverse impedance measurements in RHIC and the AGS
Biancacci, N; Blaskiewicz, M; Liu, C; Mernick, K; Minty, M; White, S
2014-01-01
The RHIC luminosity upgrade program aims for an increase of the polarized proton luminosity by a factor 2. To achieve this goal a significant increase in the beam intensity is foreseen. The beam coupling impedance represents a source of detrimental effects for beam quality and stability at high bunch intensities. In this paper, we evaluate the global transverse impedance in both the AGS and RHIC with measurements of tune shift as a function of bunch intensity. The results are compared to past measurements and the present impedance model. First attempts at transverse impedance localization are as well presented for the RHIC Blue ring.
International Nuclear Information System (INIS)
The proton Storage Ring (PSR), now in operation at Los Alamos, is a fast-cycling high-current accumulator designed to produce intense 800 MeV proton pulses for driving a spallation neutron source. This paper presents graphs of calculated longitudinal and transverse coupling impedances vs frequency for various components in the PSR beamline. The impedances are estimated using simplified formulas for the effects of steps, cavities, monitor plates, and other discontinuities in the beam pipe for the ring. An examination of stability limits indicates that the longitudinal impedance per harmonic should be less than something in the hundreds of ohms range and the transverse impedance should be less than something of the order of a megohm/meter at low frequencies. For the PSR, the impedances due to the harmonic buncher and due to possible high-Q resonances in the bump magnet chambers might be significant. Simplified growth rate estimates using the real part of the transverse impedance indicate that the bumper magnet coils for the fast kicker plates might be contributing to an observed instability with onset at about 1013 protons per bunch
The modified couple stress functionally graded Timoshenko beam formulation
International Nuclear Information System (INIS)
In this paper, a size-dependent formulation is presented for Timoshenko beams made of a functionally graded material (FGM). The formulation is developed on the basis of the modified couple stress theory. The modified couple stress theory is a non-classic continuum theory capable to capture the small-scale size effects in the mechanical behavior of structures. The beam properties are assumed to vary through the thickness of the beam. The governing differential equations of motion are derived for the proposed modified couple-stress FG Timoshenko beam. The generally valid closed-form analytic expressions are obtained for the static response parameters. As case studies, the static and free vibration of the new model are respectively investigated for FG cantilever and FG simply supported beams in which properties are varying according to a power law. The results indicate that modeling beams on the basis of the couple stress theory causes more stiffness than modeling based on the classical continuum theory, such that for beams with small thickness, a significant difference between the results of these two theories is observed.
Masato Yamakawa; Kohei Shimamura; Kimiya Komurasaki; Hiroyuki Koizumi
2014-01-01
Wireless power transfer (WPT) from a transmitter resonator on the ground to an electrically powered miniature heli-copter was attempted to demonstrate WPT using magnetic resonance coupling to an object moving in 3D space. The transmission efficiency was optimized by automatic impedance matching for different flight attitudes: a maximum flight altitude of 590 mm was achieved. Furthermore, an estimation method of transmission efficiency using only the properties on the tr...
Pulsed beam dosimetry using fiber-coupled radioluminescence detectors
DEFF Research Database (Denmark)
Andersen, Claus Erik
2012-01-01
The objective of this work was to review and discuss the potential application of fiber-coupled radioluminescence detectors for dosimetry in pulsed MV photon beams. Two types of materials were used: carbon-doped aluminium oxide (Al2O3:C) and organic plastic scintillators. Special consideration was...
Linear coupling, loss and gain of counterpropagating beams
Czech Academy of Sciences Publication Activity Database
Peřinová, V.; Lukš, A.; Křepelka, Jaromír
2006-01-01
Roč. 39, č. 9 (2006), s. 2267-2284. ISSN 0953-4075 R&D Projects: GA MŠk(CZ) OC P11.003 Institutional research plan: CEZ:AV0Z10100522; CEZ:AV0Z10100520 Keywords : linear coupling * counterpropagating beams Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.024, year: 2006
Transverse impedance measurement in RHIC and the AGS
Energy Technology Data Exchange (ETDEWEB)
Biancacci, Nicolo [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Dutheil, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mernick, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; White, S. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.
2014-05-12
The RHIC luminosity upgrade program aims for an increase of the polarized proton luminosity by a factor 2. To achieve this goal a significant increase in the beam intensity is foreseen. The beam coupling impedance could therefore represent a source of detrimental effects for beam quality and stability at high bunch intensities. For this reason it is essential to quantify the accelerator impedance budget and the major impedance sources, and possibly cure them. In this MD note we summarize the results of the 2013 transverse impedance measurements in the AGS and RHIC. The studies have been performed measuring the tune shift as a function of bunch intensity and deriving the total accelerator machine transverse impedance. For RHIC, we could obtain first promising results of impedance localization measurements as well.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
An alternative technique for crack detection in a Timoshenko beam based on the first anti-resonant frequency is presented in this paper. Unlike the natural frequency, the anti-resonant frequency is a local parameter rather than a global parameter of structures, thus the proposed technique can be used to locate the structural defects. An impedance analysis of a cracked beam stimulated by a harmonic force based on the Timoshenko beam formulation is investigated. In order to characterize the local discontinuity due to cracks, a rotational spring model based on fracture mechanics is proposed to model the crack. Subsequently, the proposed method is verified by a numerical example of a simply-supported beam with a crack. The effect of the crack size on the anti-resonant frequency is investigated. The position of the crack of the simply-supported beam is also determined by the anti-resonance technique. The proposed technique is further applied to the "contaminated" anti-resonant frequency to detect crack damage, which is obtained by adding 1-3% noise to the calculated data. It is found that the proposed technique is effective and free from the environment noise. Finally, an experimental study is performed, which further verifies the validity of the proposed crack identification technique.
International Nuclear Information System (INIS)
Detailed calculations concerning the field structure and excitation of the fast magnetosonic wave are presented keeping in mind RF heating of a Tokamak near the ion cyclotron harmonic. The new contributions are - a discussion of the cylindrical problem in an inhomogeneous plasma including surface waves and the splitting of the eigenmodes by the poloidal field - a calculation of the field structure in the toroidal cavity resonator and the application to mode tracking - a formulation of the loading impedance of various coupling structures: array of coils in the low frequency limit or transmission lines in the high frequency case
Laser beam-plasma coupling in laser solenoid plasmas
International Nuclear Information System (INIS)
A model has been constructed to analyze the gross beam-plasma interaction in a laser solenoid plasma. The model includes a simple solution for a slab plasma response to a given laser beam, and a solution for axial beam size variations in response to arbitrary axial plasma structure. The two solutions are combined to determine the coupled behavior. Trapping of the focused laser beam where it enters the plasma is a significant problem, but can be achieved by a minimum level of imbedded field in the plasma. If the beam is trapped, it first focuses and then defocuses near the front of the bleaching wave (front of the laser heated plasma). In order to avoid divergence of the beam near the front, it is essential to have a pre-formed favorable density profile in the plasma. Such a condition is probably achieved automatically in the early stages of plasma heating. Several techniques are discussed which can be used to avert unfavorable refractive behavior (catastrophic self-focusing and defocusing)
Beam engineering for selective and enhanced coupling to multipolar resonances
Das, Tanya; Schuller, Jon A
2015-01-01
Multipolar electromagnetic phenomena in sub-wavelength resonators are at the heart of metamaterial science and technology. In this letter, we demonstrate selective and enhanced coupling to specific multipole resonances via beam engineering. We first derive an analytical method for determining the scattering and absorption of spherical nanoparticles (NPs) that depends only on the local electromagnetic field quantities within an inhomogeneous beam. Using this analytical technique, we demonstrate the ability to drastically manipulate the scattering properties of a spherical NP by varying illumination properties and demonstrate the excitation of a longitudinal quadrupole mode that cannot be accessed with conventional illumination. This work enhances the understanding of fundamental light-matter interactions in metamaterials, and lays the foundation for researchers to identify, quantify, and manipulate multipolar light-matter interactions through optical beam engineering.
Beam engineering for selective and enhanced coupling to multipolar resonances
Das, Tanya; Iyer, Prasad P.; DeCrescent, Ryan A.; Schuller, Jon A.
2015-12-01
Multipolar electromagnetic phenomena in subwavelength resonators are at the heart of metamaterial science and technology. In this Rapid Communication, we demonstrate selective and enhanced coupling to specific multipole resonances via beam engineering. We first derive an analytical method for determining the scattering and absorption of spherical nanoparticles (NPs) that depends only on the local electromagnetic field quantities within an inhomogeneous beam. Using this analytical technique, we demonstrate the ability to drastically manipulate the scattering properties of a spherical NP by varying illumination properties and demonstrate the excitation of a longitudinal quadrupole mode that cannot be accessed with conventional illumination. This work enhances the understanding of fundamental light-matter interactions in metamaterials and lays the foundation for researchers to identify, quantify, and manipulate multipolar light-matter interactions through optical beam engineering.
Coupled beam motion in a storage ring with crab cavities
Energy Technology Data Exchange (ETDEWEB)
Huang, Xiaobiao [SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-11-16
We studied the coupled beam motion in a storage ring between the transverse and longitudinal directions introduced by crab cavities. Analytic form of the linear decoupling transformation is derived. Also, the equilibrium bunch distribution in an electron storage ring with a crab cavity is given, including contribution to the eigen-emittance induced by the crab cavity. Application to the short pulse generation scheme using crab cavities [1] is considered.
Collective coupling states in a quasineutral ion beam
International Nuclear Information System (INIS)
This paper discusses the possibility of the existence of spherically symmetric neutrals (electrostatic potential drops faster than 1/R) of collective coupling states formed by a large number of electrons and ions. It is shown that such states may exist in a quasineutral ion beam and in the frame of ions may be attached to the neutral plasma forming or chaotic moving electrons and ions at rest
Coupled beam motion in a storage ring with crab cavities
Huang, Xiaobiao
2015-01-01
We studied the coupled beam motion in a storage ring between the transverse and longitudinal directions introduced by crab cavities. Analytic form of the linear decoupling transformation is derived. The equilibrium bunch distribution in an electron storage ring with a crab cavity is given, including contribution to the eigen-emittance induced by the crab cavity. Application to the short pulse generation scheme using crab cavities is considered.
Coupled beam motion in a storage ring with crab cavities
Huang, Xiaobiao
2016-02-01
We studied the coupled beam motion in a storage ring between the transverse and longitudinal directions introduced by crab cavities. The analytic form of the linear decoupling transformation is derived. The equilibrium bunch distribution in an electron storage ring with a crab cavity is given, including contribution to the eigenemittance induced by the crab cavity. Application to the short pulse generation scheme using crab cavities is considered.
Directory of Open Access Journals (Sweden)
Young-Ho Park
2006-01-01
Full Text Available This paper presents the methodology for the energy flow analysis of coupled Timoshenko beam structures and various numerical applications to verify the developed methodology. To extend the application of the energy flow model for corrected flexural waves in the Timoshenko beam, which is developed in the other companion paper, to coupled structures, the wave transmission analyses of general coupled Timoshenko beam systems are performed. First, power transmission and reflection coefficients for all kinds of propagating waves in the general, coupled Timoshenko beam structures are derived by the wave transmission approach. In numerical applications, the energy flow solutions using the derived coefficients agree well with the classical solutions for various exciting frequencies, damping loss factors, and coupled Timoshenko beam structures. Additionally, the numerical results for the Timoshenko beam are compared with those for the Euler-Bernoulli beam.
Radial Moment Calculations of Coupled Electron-Photon Beams
International Nuclear Information System (INIS)
The authors consider the steady-state transport of normally incident pencil beams of radiation in slabs of material. A method has been developed for determining the exact radial moments of 3-D beams of radiation as a function of depth into the slab, by solving systems of 1-D transport equations. They implement these radial moment equations in the ONEBFP discrete ordinates code and simulate energy-dependent, coupled electron-photon beams using CEPXS-generated cross sections. Modified PN synthetic acceleration is employed to speed up the iterative convergence of the 1-D charged particle calculations. For high-energy photon beams, a hybrid Monte Carlo/discrete ordinates method is examined. They demonstrate the efficiency of the calculations and make comparisons with 3-D Monte Carlo calculations. Thus, by solving 1-D transport equations, they obtain realistic multidimensional information concerning the broadening of electron-photon beams. This information is relevant to fields such as industrial radiography, medical imaging, radiation oncology, particle accelerators, and lasers
Radial Moment Calculations of Coupled Electron-Photon Beams
Energy Technology Data Exchange (ETDEWEB)
FRANKE,BRIAN C.; LARSEN,EDWARD W.
2000-07-19
The authors consider the steady-state transport of normally incident pencil beams of radiation in slabs of material. A method has been developed for determining the exact radial moments of 3-D beams of radiation as a function of depth into the slab, by solving systems of 1-D transport equations. They implement these radial moment equations in the ONEBFP discrete ordinates code and simulate energy-dependent, coupled electron-photon beams using CEPXS-generated cross sections. Modified P{sub N} synthetic acceleration is employed to speed up the iterative convergence of the 1-D charged particle calculations. For high-energy photon beams, a hybrid Monte Carlo/discrete ordinates method is examined. They demonstrate the efficiency of the calculations and make comparisons with 3-D Monte Carlo calculations. Thus, by solving 1-D transport equations, they obtain realistic multidimensional information concerning the broadening of electron-photon beams. This information is relevant to fields such as industrial radiography, medical imaging, radiation oncology, particle accelerators, and lasers.
Dynamic impedance of piles in visco-elastic material considering axial loads
Institute of Scientific and Technical Information of China (English)
JIANG Jian-guo; ZHOU Xu-hong; ZHANG Jia-sheng
2005-01-01
The dynamic impedance function of pile in visco-elastie material considering axial loads under lateral dynamic force was analyzed, and the beam dynamic differential equation was used to induce the dynamic impedance function. After analyzing the edge conditions, the dynamic impedance functions were deduced. Contrasted with the result that does not consider axial loads, the axial loads have obvious influence on the dynamic impedance function.And the results show that the dimensionless prarmeter of the dynamic impedance will change from 6 % to 9 % when considering axial loads, and dimensionless prarmeter of the dynamic impedance of the coupling horizontal-sway will increase by 31 %.
Transverse modes and instabilities of a bunched beam with space charge and resistive wall impedance
Energy Technology Data Exchange (ETDEWEB)
Balbekov, V.; /Fermilab
2011-11-01
Transverse instability of a bunch in a ring accelerator is considered with space charge and wakefield taken into account. It is assumed that space charge tune shift significantly exceeds the synchrotron tune. Bunch spectrum, instability growth rate, and effects of chromaticity are studied with different bunch and wake forms. Fast instability caused by coupling of transverse modes is studied in detail. It is shown that, for monotonic wakes, the transverse mode coupling instability is possible only with a certain sign of the wake. Its threshold and growth rate are calculated precisely over a wide range of parameters.
International Nuclear Information System (INIS)
In 2009, prostate cancer ranked as the most common cancer and the second most fatal cancer in men in the United States. Unfortunately, the current clinical diagnostic methods (e.g. prostate-specific antigen (PSA), digital rectal examination, endorectal MRI, transrectal ultrasound, biopsy) used for detecting and staging prostate cancer are limited. It has been shown that cancerous prostate tissue has significantly different electrical properties when compared to benign tissues. Based on these electrical property findings, a transrectal electrical impedance tomography (TREIT) system is proposed as a novel prostate imaging modality. The TREIT system comprises an array of electrodes interfaced with a clinical transrectal ultrasound (TRUS) probe. We evaluate this imaging system through a series of phantom imaging experiments to assess the system's ability to image high and low contrast objects at various positions. We found that the TREIT system can easily discern high contrast inclusions of 1 cm in diameter at distances centered at two times the radius of the TREIT probe away from the probe surface. Furthermore, this technology's ability to detect low contrast inclusions suggests that it has the potential to successfully detect prostate cancer
Pulsed beam dosimetry using fiber-coupled radioluminescence detectors
DEFF Research Database (Denmark)
Andersen, Claus Erik
2012-01-01
The objective of this work was to review and discuss the potential application of fiber-coupled radioluminescence detectors for dosimetry in pulsed MV photon beams. Two types of materials were used: carbon-doped aluminium oxide (Al2O3:C) and organic plastic scintillators. Special consideration was...... given to the discrimination between radioluminescence signals from the phosphors and unwanted light induced in the optical fiber cables during irradiation (Cerenkov and fluorescence). New instrumentation for dose-per-pulse measurements with organic plastic scintillators was developed....
International Nuclear Information System (INIS)
Experiments have proven that both the surface contaminants and microstructure topography on the cathode of an electron beam diode influence impedance collapse and electron emission current. Experiments have characterized effective RF plasma processing protocols for high voltage A-K gaps using argon and argon/oxygen gas mixtures. RF processing time, feed gas pressure, and RF power were adjusted. Time resolved optical emission spectroscopy measured contaminant (hydrogen) and bulk cathode (aluminum) plasma emission versus transported axial electron beam current. Experiments utilize the Michigan Electron Long Beam Accelerator (MELBA) at parameters: V = -0.7 to minus1.0 MV, I(diode) + 3--30 kA, and pulse length = 0.4 to 1.0 microseconds. Microscopic and macroscopic E-fields on the cathode were varied to characterize the scaling of breakdown conditions for contaminants versus the bulk material of the cathode after plasma processing. Electron emission was suppressed for an aluminum cathode in a high voltage A-K gap after RF plasma processing. Experiments using a two-state low power (100W) argon/oxygen RF discharge followed by a higher power (200W) pure argon RF discharge yielded an increase in turn-on voltage required for axial current emission from 662 ± 174 kV to 981 ± 97 kV. After two-stage RF plasma processing axial current emission turn-on time was increased from 100 ± 22 nanoseconds to 175 ± 42 nanoseconds. Aluminum optical emission was delayed > 150 nanoseconds after the overshoot in voltage after two-stage RF plasma processing. Removal of hydrogen contamination on the cathode surface was observed by optical spectroscopy during the MELBA pulse. Axial and diode current were reduced 40--100% after RF plasma processing. SEM analysis suggests the aluminum cathode surface is being modified by the RF plasma discharge
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
accurate temperature estimation either vertically or horizontally inside the power devices is still hard to identify. This paper investigates the thermal behavior of high power module in various operating conditions by means of Finite Element Method (FEM). A novel 3D thermal impedance network considering...... the multi-layer thermal coupling among chips is proposed. The impacts to the thermal impedance by various cooling and heating conditions are also studied. It is concluded that the heating and cooling conditions will have influence on the junction to case thermal impedances and need to be carefully...... considered in the thermal modelling. The proposed 3D thermal impedance network and the extraction procedure are verified in a circuit simulator and shows to be much faster with the same accuracy compared to FEM simulation. This network can be used for life-time estimation of IGBT module considering the whole...
Semenova, N.; Zakharova, A.; Schöll, E.; Anishchenko, V.
2015-11-01
We analyze nonlocally coupled networks of identical chaotic oscillators with either time-discrete or time-continuous dynamics (Henon map, Lozi map, Lorenz system). We hypothesize that chimera states, in which spatial domains of coherent (synchronous) and incoherent (desynchronized) dynamics coexist, can be obtained only in networks of oscillators with nonhyperbolic chaotic attractors and cannot be found in networks of systems with hyperbolic chaotic attractors. This hypothesis is supported by analytical results and numerical simulations for hyperbolic and nonhyperbolic cases.
Thermal Impedance Model of High Power IGBT Modules Considering Heat Coupling Effects
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
2014-01-01
Thermal loading of Insulated Gate Bipolar Transistor (IGBT) modules is important for the reliability performance of power electronic systems, thus the thermal information of critical points inside module like junction temperature must be accurately modeled and predicted. Usually in the existing thermal models, only the self-heating effects of the chips are taken into account, while the thermal coupling effects among chips are less considered. This could result in inaccurate temperature estima...
Mattei, P.-O.; Ponçot, R.; Pachebat, M.; Côte, R.
2016-07-01
In order to control the sound radiation by a structure, one aims to control vibration of radiating modes of vibration using "Energy Pumping" also named "Targeted Energy Transfer". This principle is here applied to a simplified model of a double leaf panel. This model is made of two beams coupled by a spring. One of the beams is connected to a nonlinear absorber. This nonlinear absorber is made of a 3D-printed support on which is clamped a buckled thin small beam with a small mass fixed at its centre having two equilibrium positions. The experiments showed that, once attached onto a vibrating system to be controlled, under forced excitation of the primary system, the light bistable oscillator allows a reduction of structural vibration up to 10 dB for significant amplitude and frequency range around the first two vibration modes of the system.
Gamp, Alexander
2013-01-01
We begin by giving a description of the radio-frequency generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, radio-frequency feedback and feedforward are described. Examples of digital radio-frequency phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
Impedance and Collective Effects
Metral, E; Rumolo, R; Herr, W
2013-01-01
This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling
2016-01-01
Proposal to negotiate three collaboration agreements in the context of the Future Circular Collider Study (FCC) concerning the development of HTS coated tapes integrated into the beam screen for impedance mitigation
Rotaru, M.; Tan, Yen Kheng; Sykulski, J.K.
2014-01-01
The input impedance of a wireless power transfer system is heavily influenced by variation of the load impedance, distance between coils and presence of any massive conducting or shielding structures that may exist around the system. To achieve the maximum efficiency for the wireless link transfer one has to ensure good matching between the power source and the wireless power transfer (WPT) system for different working conditions. In this paper an equivalent circuit of the WPT which accoun...
Varshney, Madhukar; Li, Yanbin
2007-05-15
An impedance biosensor based on interdigitated array microelectrode (IDAM) coupled with magnetic nanoparticle-antibody conjugates (MNAC) was developed and evaluated for rapid and specific detection of E. coli O157:H7 in ground beef samples. MNAC were prepared by immobilizing biotin-labeled polyclonal goat anti-E. coli antibodies onto streptavidin-coated magnetic nanoparticles, which were used to separate and concentrate E. coli O157:H7 from ground beef samples. Magnitude of impedance and phase angle were measured in a frequency range of 10 Hz to 1 MHz in the presence of 0.1M mannitol solution. The lowest detection limits of this biosensor for detection of E. coli O157:H7 in pure culture and ground beef samples were 7.4 x 10(4) and 8.0 x 10(5)CFU ml(-1), respectively. The regression equation for the normalized impedance change (NIC) versus E. coli O157:H7 concentration (N) in ground beef samples was NIC=15.55 N-71.04 with R(2)=0.95. Sensitivity of the impedance biosensor was improved by 35% by concentrating bacterial cells attached to MNAC in the active layer of IDAM above the surface of electrodes with the help of a magnetic field. Based on equivalent circuit analysis, it was observed that bulk resistance and double layer capacitance were responsible for the impedance change caused by the presence of E. coli O157:H7 on the surface of IDAM. Surface immobilization techniques, redox probes, or sample incubation were not used in this impedance biosensor. The total detection time from sampling to measurement was 35 min. PMID:17045791
Evaluation of the broadband longitudinal impedance of the CERN PS
Damerau, H; Hancock, S; Migliorati, M; Palumbo, L; Persichelli, S; CERN. Geneva. ATS Department
2012-01-01
The CERN Proton Synchrotron (PS) produces beams well beyond its original parameters and especially the high-brightness beams delivered to the Large Hadron Collider are close to present stability limitations. Within the framework of the LHC Injectors Upgrade project, a signicant increase in beam intensity is planned. With this background, collective effects triggered by the self-induced electromagnetic elds, which are generated by the interaction of the beam with the surrounding environment, may play an important role in beam stability and machine performance. In this paper we study the short range wakeelds and the corresponding longitudinal broadband coupling impedance of the PS by measuring the incoherent quadrupole synchrotron frequency as a function of beam intensity and comparing the results with the evaluation of the contribution of several machine installations to the total impedance budget.
Simulation study of LEBT for transversely coupled beam from an ECR ion source
International Nuclear Information System (INIS)
A Low-Energy intense-highly charged ion Accelerator Facility (LEAF) program has been launched at Institute of Modern Physics. This accelerator facility consists of a superconducting Electron Cyclotron Resonance (ECR) ion source, a Low Energy Beam Transport (LEBT) system, and a Radio Frequency Quadrupole (RFQ). It is especially of interest for the extracted ion beam from the ECR ion source, which is transversely coupled, and this property will significantly affect the beam transmission in the LEBT line and the matching with the downstream RFQ. In the beam transport design of LEAF, beam decoupling in the LEBT is considered to lower down the projection emittances and the feasibility of the design has been verified by beam simulation with a transversely coupled beam from the ECR ion source
Simulation study of LEBT for transversely coupled beam from an ECR ion source
Energy Technology Data Exchange (ETDEWEB)
Yang, Y., E-mail: yangyao@impcas.ac.cn [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Dou, W. P.; Sun, L. T.; Yao, Q. G.; Zhang, Z. M.; Yuan, Y. J.; He, Y.; Zh, X. Z.; Zhao, H. W. [Institute of Modern Physics, CAS, Lanzhou 730000 (China)
2016-02-15
A Low-Energy intense-highly charged ion Accelerator Facility (LEAF) program has been launched at Institute of Modern Physics. This accelerator facility consists of a superconducting Electron Cyclotron Resonance (ECR) ion source, a Low Energy Beam Transport (LEBT) system, and a Radio Frequency Quadrupole (RFQ). It is especially of interest for the extracted ion beam from the ECR ion source, which is transversely coupled, and this property will significantly affect the beam transmission in the LEBT line and the matching with the downstream RFQ. In the beam transport design of LEAF, beam decoupling in the LEBT is considered to lower down the projection emittances and the feasibility of the design has been verified by beam simulation with a transversely coupled beam from the ECR ion source.
Simulation study of LEBT for transversely coupled beam from an ECR ion source
Yang, Y.; Dou, W. P.; Sun, L. T.; Yao, Q. G.; Zhang, Z. M.; Yuan, Y. J.; He, Y.; Zh, X. Z.; Zhao, H. W.
2016-02-01
A Low-Energy intense-highly charged ion Accelerator Facility (LEAF) program has been launched at Institute of Modern Physics. This accelerator facility consists of a superconducting Electron Cyclotron Resonance (ECR) ion source, a Low Energy Beam Transport (LEBT) system, and a Radio Frequency Quadrupole (RFQ). It is especially of interest for the extracted ion beam from the ECR ion source, which is transversely coupled, and this property will significantly affect the beam transmission in the LEBT line and the matching with the downstream RFQ. In the beam transport design of LEAF, beam decoupling in the LEBT is considered to lower down the projection emittances and the feasibility of the design has been verified by beam simulation with a transversely coupled beam from the ECR ion source.
Institute of Scientific and Technical Information of China (English)
Zhang Bing-Zhi; Cui Hu; She Wei-Long
2009-01-01
The modulational instability of two incoherently coupled beams in azobenzene-containing polymer with photoisomerization nonlinearity is investigated analytically and numerically. Our results show that as a precursor to spatial optical soliton formation, modulational instability can be adjusted and controlled by the wavelength combinations of the signal and background beams. We also discuss the dependences of strength of modulational instability on intensities of two signal beams and background beam. These findings make it possible to predict the formation of incoherently coupled soliton pairs in azobenzene-containing polymer.
International Nuclear Information System (INIS)
The modulational instability of two incoherently coupled beams in azobenzene-containing polymer with photoisomerization nonlinearity is investigated analytically and numerically. Our results show that as a precursor to spatial optical soliton formation, modulational instability can be adjusted and controlled by the wavelength combinations of the signal and background beams. We also discuss the dependences of strength of modulational instability on intensities of two signal beams and background beam. These findings make it possible to predict the formation of incoherently coupled soliton pairs in azobenzene-containing polymer. (classical areas of phenomenology)
Impedance and component heating
Métral, E; Mounet, N; Pieloni, T; Salvant, B
2015-01-01
The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.
Impedance and instability threshold estimates in the main injector I
Energy Technology Data Exchange (ETDEWEB)
Martens, M.A.; Ng, K.Y.
1994-03-01
One of the important considerations in the design of the Main Injector is the beam coupling impedances in the vacuum chamber and the stability of the beam. Along with the higher intensities comes the possibility of instabilities which lead to growth in beam emittances and/or the loss of beam. This paper makes estimations of the various impedances and instability thresholds based on impedance estimations and measurements. Notably missing from this paper is any analysis of transition crossing and its potential limitations on beam intensity and beam emittance. Future work should consider this issue. The body of the work contains detailed analysis of the various impedance estimations and instability threshold calculations. The calculations are based on the Main Injector beam intensity of 6 x 10{sup 10} protons per bunch, 95% normalized transverse emittances of 20{pi} mm-mrad, and 95% normalized longitudinal emittance of 0.1 eV-s at 8.9 GeV injection energy and 0.25 eV-s at 150 GeV flattop energy. The conclusions section summarizes the results in the paper and is meant to be readable by itself without referring to the rest of the paper. Also in the conclusion section are recommendations for future investigations.
Impedance and instability threshold estimates in the main injector I
International Nuclear Information System (INIS)
One of the important considerations in the design of the Main Injector is the beam coupling impedances in the vacuum chamber and the stability of the beam. Along with the higher intensities comes the possibility of instabilities which lead to growth in beam emittances and/or the loss of beam. This paper makes estimations of the various impedances and instability thresholds based on impedance estimations and measurements. Notably missing from this paper is any analysis of transition crossing and its potential limitations on beam intensity and beam emittance. Future work should consider this issue. The body of the work contains detailed analysis of the various impedance estimations and instability threshold calculations. The calculations are based on the Main Injector beam intensity of 6 x 1010 protons per bunch, 95% normalized transverse emittances of 20π mm-mrad, and 95% normalized longitudinal emittance of 0.1 eV-s at 8.9 GeV injection energy and 0.25 eV-s at 150 GeV flattop energy. The conclusions section summarizes the results in the paper and is meant to be readable by itself without referring to the rest of the paper. Also in the conclusion section are recommendations for future investigations
Lee, Hohyoung; Lee, Jeongbeom; Park, Gijung; Han, Yunseok; Lee, Youngwook; Cho, Gunhee; Kim, Hanam; Chang, Hongyoung; Min, Kyoungwook
2015-08-01
A high-speed impedance measurement system was developed, which enables the measurement of various characteristics of CW and pulsed plasmas with time resolution of less than a microsecond. For this system, a voltage and current sensor is implemented in a printed circuit board to sense the radio frequency signals. A digital board, which has a high-speed analog to digital converter and a field-programmable gate-array, is used to calculate the impedance of the signal. The final output of impedance is measured and stored with a maximum speed of 3 Msps. This sensor system was tested in a pulsed-plasma by applying it to the point between the matching box and the plasma chamber. The experimental equipment was constructed connecting the matching box, a 13.56 MHz generator, a 2 MHz generator that produced pulsed power, and a pulse-signal generator. From the temporal behavior of the measured impedance, we were able to determine the time intervals of transient states, especially of the initial active state. This information can be used to set the pulse frequency and duty for plasma processing. PMID:26329190
On sixfold coupled vibrations of thin-walled composite box beams
Vo, Thuc; Lee, Jaehong; Ahn, Namshik
2009-01-01
This paper presents a general analytical model for free vibration of thin-walled composite beams with arbitrary laminate stacking sequences and studies the effects of shear deformation over the natural frequencies. This model is based on the first-order shear-deformable beam theory and accounts for all the structural coupling coming from the material anisotropy. The seven governing differential equations for coupled flexural–torsional–shearing vibration are derived from the Hamilton’s princip...
Impedance model of the CERN SPS and aspects of LHC single-bunch stability
Salvant, Benoit; Metral, Elias
2010-01-01
Upgrades of the CERN particle accelerators complex are planned to increase the potential of physics discovery in the LHC. In this respect, the beam coupling impedances of the SPS and LHC are expected to be among the limitations to the intensity upgrade scheme. In this thesis work, we present a general framework to better understand the impedance of a particle accelerator. In a first step, the impedance of single components are gathered into an impedance model accounting for the whole machine. In order to assess the relevance of this impedance model, its impact on beam dynamics is simulated and can be compared to impedance observables measured with beam. This general framework was applied to compute a more accurate transverse impedance model of the SPS from theoretical models for the 20 kickers and the 6.9 km long beam pipe, as well as time domain electromagnetic simulations of the 106 horizontal and 96 vertical SPS beam position monitors. Comparing HEADTAIL macroparticle simulations to beam-based measurements...
PEP-X IMPEDANCE AND INSTABILITY CALCULATIONS
Energy Technology Data Exchange (ETDEWEB)
Bane, K.L.F.; Lee, L.-Q.; Ng, C.; Stupakov, G.; au Wang, L.; Xiao, L.; /SLAC
2010-08-25
PEP-X, a next generation, ring-based light source is designed to run with beams of high current and low emittance. Important parameters are: energy 4.5 GeV, circumference 2.2 km, beam current 1.5 A, and horizontal and vertical emittances, 185 pm by 8 pm. In such a machine it is important that impedance driven instabilities not degrade the beam quality. In this report they study the strength of the impedance and its effects in PEP-X. For the present, lacking a detailed knowledge of the vacuum chamber shape, they create a straw man design comprising important vacuum chamber objects to be found in the ring, for which they then compute the wake functions. From the wake functions they generate an impedance budget and a pseudo-Green function wake representing the entire ring, which they, in turn, use for performing microwave instability calculations. In this report they, in addition, consider in PEP-X the transverse mode-coupling, multi-bunch transverse, and beam-ion instabilities.
Beam steering via resonance detuning in coherently coupled vertical cavity laser arrays
International Nuclear Information System (INIS)
Coherently coupled vertical-cavity surface-emitting laser arrays offer unique advantages for nonmechanical beam steering applications. We have applied dynamic coupled mode theory to show that the observed temporal phase shift between vertical-cavity surface-emitting array elements is caused by the detuning of their resonant wavelengths. Hence, a complete theoretical connection between the differential current injection into array elements and the beam steering direction has been established. It is found to be a fundamentally unique beam-steering mechanism with distinct advantages in efficiency, compactness, speed, and phase-sensitivity to current
Richardson, John G.
2009-11-17
An impedance estimation method includes measuring three or more impedances of an object having a periphery using three or more probes coupled to the periphery. The three or more impedance measurements are made at a first frequency. Three or more additional impedance measurements of the object are made using the three or more probes. The three or more additional impedance measurements are made at a second frequency different from the first frequency. An impedance of the object at a point within the periphery is estimated based on the impedance measurements and the additional impedance measurements.
Improved techniques of impedance calculation and localization in particle accelerators
Biancacci, Nicolò; Migliorati, Mauro; Métral, Elias; Salvant, Benoit
In this thesis we mainly focus on particle accelerators applied to high energy physics research where a fundamental parameter, the luminosity, is maximized in order to increase the rate of particle collisions useful to particle physicists. One way to increase this parameter is to increase the intensity of the circulating beams which is limited by the onset of collective effects that may drive the beam unstable and eventually provoke beam losses or reduce the beam quality required by the particle physics experiments. One major cause of collective effects is the beam coupling impedance, a quantity that quantifies the effect of the fields scattered by a beam passing through any accelerator device. The development of an impedance budget is required in those machines that are planning substantial upgrades as shown in this thesis for the CERN PS case. The main source of impedance in the CERN LHC are the collimators. Within an impedance reduction perspective, in order to reach the goals of the planned upgrades, it ...
Probing anomalous Higgs couplings at an collider using unpolarised beams
Indian Academy of Sciences (India)
Debajyoti Choudhury; Mamta
2007-11-01
We examine the sensitivity of colliders (based on + - linear colliders of c.m. energy 500 GeV) to the anomalous couplings of the Higgs to -boson via the process - → . This has the advantage over + - collider in being able to dissociate vertex from . We are able to construct several dynamical variables which may be used to constrain the various couplings in the vertex.
Efficient coupling of propagating broadband terahertz radial beams to metal wires.
Zheng, Zhu; Kanda, Natsuki; Konishi, Kuniaki; Kuwata-Gonokami, Makoto
2013-05-01
Bare metal wires have recently been demonstrated as waveguides for transporting terahertz (THz) radiation, where the guiding mode is radially polarized surface Sommerfeld waves. In this study, we demonstrate high-efficiency coupling of a broadband radially polarized THz pulsed beam, which is generated with a polarization-controlled beam by a segmented half-wave-plate mode converter, to bare copper wires. A total coupling efficiency up to 16.8% is observed, and at 0.3 THz, the maximum coupling efficiency is 66.3%. The results of mode-overlap calculation and numerical simulation support the experimental data well. PMID:23669920
Caspers, Friedhelm; Iriso-Ariz, U
2003-01-01
The classical 2 wire method is not suitable for high precision transverse impedance measurements on a homogeneous copper beampipe with non-circular cross-section due to measurement noise limitations in case of narrow wire spacing. Thus we tackled the problem by simulating the 2D electrostatic field and image charge distribution of that setup and subsequently calculating the corresponding surface current for a TEM wave excitation. In this computer simulation the 2 wires can be assumed lossless, which is not possible in a practical bench setup. The theoretical justification for the method and certain limitations are discussed. The results obtained compare very well to several independent numerical and analytical results.
Observations involving broadband impedance modelling
Energy Technology Data Exchange (ETDEWEB)
Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)
1996-08-01
Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)
Dynamics of beam pair coupled by visco-elastic interlayer
Czech Academy of Sciences Publication Activity Database
Náprstek, Jiří; Hračov, Stanislav
2015-01-01
Roč. 9, č. 2 (2015), s. 127-140. ISSN 1802-680X R&D Projects: GA ČR(CZ) GP13-41574P; GA ČR(CZ) GA15-01035S Institutional support: RVO:68378297 Keywords : double-beam dynamics * visco-elastic interlayer * kinematic damping Subject RIV: JM - Building Engineering http://www.kme.zcu.cz/acm/acm/article/view/292
Couroussé, Damien
2007-01-01
Mechanical impedance is a transposition to mechanics of the term impedance that is used and defined in circuit theory. The theory of circuit (theory of Kirchhoff networks) is basically applicable to electric networks but can be considered more generally as a unifying simplified theory of physics available in several domains like mechanics, electromagnetism, aero-acoustics and fluids mechanics.
Matrix solution to longitudinal impedance of multi-layer circular structures
Energy Technology Data Exchange (ETDEWEB)
Hahn,H.
2008-10-01
A matrix method in which radial wave propagation is treated in analogy to longitudinal transmission lines is presented and applied to finding the longitudinal coupling impedance of axially symmetric multi-layer beam tubes. The method is demonstrated in the case of a Higher Order Mode ferrite absorber with an inserted coated ceramic beam tube. The screening of the ferrite damping properties by the dielectric beam tube is discussed.
Beam optimization of helium injector for coupled RFQ–SFRFQ linac
International Nuclear Information System (INIS)
The coupled RFQ–SFRFQ (CRS) cavity designed in Peking University is a new type linac that coupled radio frequency quadrupole (RFQ) and separated function radio frequency quadrupole (SFRFQ) structure into a single cavity. An upgraded helium injector for the CRS cavity consisting of a 2.45 GHz permanent magnet electron cyclotron resonance (ECR) ion source and a 1.16 m low energy beam transport (LEBT) has been constructed and tested. The beam conditions of the injector were carefully optimized to satisfy the requirements of the CRS linac, the corresponding control system and a two-dimension scanner code CRSv1.0 were developed for optimizing the beam transmission from LEBT section to the entrance of the CRS cavity. The beam transmission efficiency has reached to approximately 87.5% as well as the optimized operating parameters were obtained by means of the scanner code
Impedances for electron linacs and storage rings
International Nuclear Information System (INIS)
Some basic concepts and results are presented concerning the impedances of electron linacs and storage rings. The impedances of an accelerator or ring completely characterizes the interaction of the beam with its environment. Not only does the impedance (or its Fourier transform, the wake potential) determine the energy loss by a bunched beam to its environment, but it is also the chief ingredient required for any calculation of beam stability
Pump Intensity Dependence of Two-Beam Coupling in Doped Lithium Niobate Crystals
Institute of Scientific and Technical Information of China (English)
Nouel Y.Kamber; XU Jing-Jun; Sonia M. Mikha; SONG Feng; ZHANG Guo-Quan; ZHANG Xin-Zheng; LIU Si-Min; ZHANG Guang-Yin
2000-01-01
We demonstrated experimentally the dependence of two-beam coupling on the incident pump intensity in our samples of doped LiNbO3 crystals. Our results show that there is an optimum pump intensity for the signal beam amplification, which can be easily controlled by doping the LiNbO3 crystal with suitable concentrations of Fe and damage-resistant dopants such as Mg, In, and Zn.
Two-line-coupling beam-quality effects in stimulated Raman scattering
International Nuclear Information System (INIS)
The authors present the results of calculations of the beam quality obtainable in a collimated, single-beam Raman beam cleanup system, in which the pump laser contains two lines whose frequency separation is enough to cause significant dispersive ''slip'' between them in the Raman amplifier. A specific example is the 351-353 nm line pair of an XeF laser. They start from equations coupling the various modes of the lines and their corresponding Stokes modes. Refractivity effects caused by nonuniform Raman-induced population transfer are specifically accounted for. The impact on beam quality is assessed as a function of the pressure in a H/sub 2/ Raman amplifier, and it is shown that the minimum effect occurs at a pressure of 2.4 Atm, for which the motionally narrowed Raman linewidth takes its minimum value. The two-line coupling causes the population transfer due to the stronger of the two lines to adversely affect the beam quality of the weaker line. For an rms percent fluence modulation of 15 percent, the two-line coupling lowers the Strehl ratio (a measure of beam quality) by --15 percent for a 1-μs XeF laser pulse length
200-mm-diameter neutral beam source based on inductively coupled plasma etcher and silicon etching
International Nuclear Information System (INIS)
The authors developed a neutral beam source consisting of a 200-mm-diameter inductively coupled plasma etcher and a graphite neutralization aperture plate based on the design of a neutral beam source that Samukawa et al. [Jpn. J. Appl. Phys., Part 2 40, L779 (2001)] developed. They measured flux and energy of neutral particles, ions, and photons using a silicon wafer with a thermocouple and a Faraday cup and calculated the neutralization efficiency. An Ar neutral beam flux of more than 1 mA/cm2 in equivalent current density and a neutralization efficiency of more than 99% were obtained. The spatial uniformity of the neutral beam flux was within ±6% within a 100 mm diameter. Silicon etching using a F2-based neutral beam was done at an etch rate of about 47 nm/min, while Cl2-based neutral beam realized completely no undercut. The uniformity of etch rate was less than ±5% within the area. The etch rate increased by applying bias power to the neutralization aperture plate, which shows that accelerated neutral beam was successfully obtained. These results indicate that the neutral beam source is scalable, making it possible to obtain a large-diameter and uniform neutral beam, which is inevitable for application to mass production.
Picosecond enhancement of photorefractive beam coupling in CdTe:V at 960 nm
Andreas Schroeder, W.; Stark, Thomas S.; Smirl, Arthur L.; Valley, George C.
1991-08-01
Photorefractive beam coupling in CdTe:V is observed with single 1 ps pulses at a wavelength of 960 nm. Coupling coefficients are substantially larger than observed with 30 ps pulses at 1.06 μm and nearly a factor of 100 larger than calculations based on conventional transport properties of CdTe. We consider anomalously large carrier diffusion (hot carriers) as a possible mechanism for the production of this nonlocal photorefractive grating.
International Nuclear Information System (INIS)
Light amplification due to two-beam coupling is realized in doped polymethyl methacrylate (PMMA) glasses. A coupling gain as large as 14 cm-1 is obtained. The dynamic behaviour of absorption and light-induced scattering due to the process of photopolymerization are also studied. The results show that the amplification and its dynamic process enable possible applications of PMMA in optical devices. (fundamental areas of phenomenology (including applications))
Terahertz Quantum Cascade Laser With Efficient Coupling and Beam Profile
Chattopadhyay, Goutam; Kawamura, Jonathan H.; Lin, Robert H.; Williams, Benjamin
2012-01-01
Quantum cascade lasers (QCLs) are unipolar semiconductor lasers, where the wavelength of emitted radiation is determined by the engineering of quantum states within the conduction band in coupled multiple-quantum-well heterostructures to have the desired energy separation. The recent development of terahertz QCLs has provided a new generation of solid-state sources for radiation in the terahertz frequency range. Terahertz QCLs have been demonstrated from 0.84 to 5.0 THz both in pulsed mode and continuous wave mode (CW mode). The approach employs a resonant-phonon depopulation concept. The metal-metal (MM) waveguide fabrication is performed using Cu-Cu thermo-compression bonding to bond the GaAs/AlGaAs epitaxial layer to a GaAs receptor wafer.
Anderson, Karl F. (Inventor)
1994-01-01
A constant current loop measuring system is provided for measuring a characteristic of an environment. The system comprises a first impedance positionable in the environment, a second impedance coupled in series with said first impedance and a parasitic impedance electrically coupled to the first and second impedances. A current generating device, electrically coupled in series with the first and second impedances, provides a constant current through the first and second impedances to produce first and second voltages across the first and second impedances, respectively, and a parasitic voltage across the parasitic impedance. A high impedance voltage measuring device measures a voltage difference between the first and second voltages independent of the parasitic voltage to produce a characteristic voltage representative of the characteristic of the environment.
Impedance studies of 2D azimuthally symmetric devices of finite length
Biancacci, N; Métral, E; Salvant, B; Migliorati, M; Palumbo, L
2014-01-01
In particle accelerators, the beam quality can be strongly affected by the interaction with self-induced electromagnetic fields excited by the beam in the passage through the elements of the accelerator. The beam coupling impedance quantifies this interaction and allows predicting the stability of the dynamics of high intensity, high brilliance beams. The coupling impedance can be evaluated with finite element methods or using analytical approaches, such as field matching or mode matching. In this paper we present an application of the mode matching technique for an azimuthally uniform structure of finite length: a cylindrical cavity loaded with a toroidal slab of lossy dielectric, connected with cylindrical beam pipes. In order to take into account the finite length of the structure, with respect to the infinite length approximation, we decompose the fields in the cavity into a set of orthonormal modes. We obtain a complete set of equations using the magnetic field matching and the nonuniform convergence of ...
Gamp, A
2011-01-01
We begin by giving a description of the rf generator-cavity-beam coupled system in terms of basic quantities. Taking beam loading and cavity detuning into account, expressions for the cavity impedance as seen by the generator and as seen by the beam are derived. Subsequently methods of beam-loading compensation by cavity detuning, rf feedback, and feed-forward are described. Examples of digital rf phase and amplitude control for the special case of superconducting cavities are also given. Finally, a dedicated phase loop for damping synchrotron oscillations is discussed.
International Nuclear Information System (INIS)
Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation ±0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibility of the system was ±0.55% for dose fractions of ∼100 cGy. Energy dependence was within ±1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R2=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within ±0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.
Nonlinear dynamics of magnetically coupled beams for multi-modal vibration energy harvesting
Abed, I.; Kacem, N.; Bouhaddi, N.; Bouazizi, M. L.
2016-04-01
We investigate the nonlinear dynamics of magnetically coupled beams for multi-modal vibration energy harvesting. A multi-physics model for the proposed device is developed taking into account geometric and magnetic nonlinearities. The coupled nonlinear equations of motion are solved using the Galerkin discretization coupled with the harmonic balance method and the asymptotic numerical method. Several numerical simulations have been performed showing that the expected performances of the proposed vibration energy harvester are significantly promising with up to 130 % in term of bandwidth and up to 60 μWcm-3g-2 in term of normalized harvested power.
High flux cold Rubidium atomic beam for strongly coupled Cavity QED
Roy, Basudev
2012-01-01
This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity QED experiments in the regime of strong coupling. A 2 $D^+$ MOT, loaded by rubidium getters in a dry film coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate of 1.5 x $10^{10}$ atoms/sec. The MM-MOT provided a continuous beam with tunable velocity. This beam was then directed through the waist of a 280 $\\mu$m cavity resulting in a Rabi splitting of more than +/- 10 MHz. The presence of sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling regime, with parameters (g, $\\kappa$, $\\gamma$)/2$\\pi$ equal to (7, 3, 6)/ 2$\\pi$ MHz.
Computer simulation model of reflex e-beam systems coupled to an external circuit
International Nuclear Information System (INIS)
Dynamics of ions and relativistic electrons in various high-voltage reflexing systems (reflex diodes and triodes) was investigated numerically by means of 1 1/2-dimensional PIC simulation model OREBIA. Its perfected version OREBIA-REX also accounts for system coupling to an external power source circuit, thus yielding the currents and applied voltage self-consistently. Various modes of operation of reflex diode and triode were studied using both models. It is shown that neglecting the influence of the external circuit can lead to seve--re overestimation of both ion currents and electron accumulation rates. In coupled systems with ions repeated collapses of impedance due to electron-ion relaxation processes are observed. The current and voltage pulses calculated for several reflex diodes and triodes with and without ions are presented. (J.U.)
Coupling between eddy current and deflection in cantilevered beams in magnetic fields
International Nuclear Information System (INIS)
Experiments were performed to investigate the coupling between eddy currents and deflection in cantilevered beams in longitudinal and transverse magnetic fields. This coupling effect reduces the current, deflection, and material stress to levels far less severe than would be predicted if coupling is disregarded. The experiments were conducted using the FELIX (Fusion ELectromagnetic Induction experiment) facility at the Argonne National Laboratory. The beams, which provide a simple model for the limiter blades in a tokamak fusion reactor, are subjected to crossed time-varying and constant magnetic fields. The time-varying field simulates the decaying field during a plasma disruption and the constant field models the toroidal field. Several test pieces are employed to allow variations in thicknesses and mechanical and electrical properties. Various magnetic field levels and decay time constants of time-varying are used to study the extent of the coupling from weak to strong coupling. The ratios of constant field to time-varying field are kept in the range from 10:1 to 20:1 as would be appropriate to tokamak limiters. Major parameters measured as functions of time are beam deflection, measured with an electro-optical device; total circulating current, measured with a Rogowski coil; strain recorded by strain gauges; and magnetic fields measured with Hall probes
Anomalous WWγ couplings with beam polarization at the Compact Linear Collider
Arı, V.; Billur, A. A.; İnan, S. C.; Köksal, M.
2016-05-01
We study the anomalous WWγ couplings at the Compact Linear Collider through the processes e+e- →W+W-, e-e+ →e-γ*e+ →e+νeW- and e-e+ →e-γ*γ*e+ →e-W+W-e+ (γ* is the Weizsacker-Williams photon). We give the 95% confidence level limits for unpolarized and polarized electron (positron) beam on the anomalous couplings for various values of the integrated luminosities and center-of-mass energies. We show that the obtained limits on the anomalous couplings through these processes can highly improve the current experimental limits. In addition, our limits with beam polarization are approximately two times better than the unpolarized case.
ANALYSIS OF COMPOSITE LAMINATE BEAMS USING COUPLING CROSS-SECTION FINITE ELEMENT METHOD
Institute of Scientific and Technical Information of China (English)
JIANG Wen-guang; John L. Henshall
2006-01-01
Beams and plates manufactured from laminates of composite materials have distinct advantages in a significant number of applications. However, the anisotropy arising from these materials adds a significant degree of complexity, and thus time, to the stress and deformation analyses of such components, even using numerical approaches such as finite elements. The analysis of composite laminate beams subjected to uniform extension, bending, and/or twisting loads was performed by a novel implementation of the usual finite element method. Due to the symmetric features of the deformations,only a thin slice of the beam to be analysed needs to be modelled. Conventional threedimensional ,solid finite elements were used for the structural discretization. The accurate deformation relationships were formulated and implemented through the coupling of nodal translational degrees of freedom in the numerical analysis. A sample solution for a rectangular composite laminate beam is presented to show the validity and accuracy of the proposed method.
Andreazza, W; Bravin, E; Caspers, F; Garlasch`e, M; Gras, J; Goldblatt, A; Lefevre, T; Jones, R; Metral, E; Nosych, A; Roncarolo_, F; Salvant, B; Trad, G; Veness, R; Vollinger, C; Wendt, M
2013-01-01
The CERN LHC is equipped with two Synchrotron Radiation Monitor (BSRT) systems used to characterise transverse and longitudinal beam distributions. Since the end of the 2011 LHC run the light extraction system, based on a retractable mirror, has suffered deformation and mechanical failure that is correlated to the increase in beam intensity. Temperature probes have associated these observations to a strong heating of the mirror support with a dependence on the longitudinal bunch length and shape, indicating the origin as electromagnetic coupling between the beam and the structure. This paper combines all this information with the aim of characterising and improving the system in view of its upgrade during the current LHC shutdown. Beam-based observations are presented along with electromagnetic and thermomechanical simulations and complemented by laboratory measurements, including the study of the RF properties of different mirror bulk and coating materials.
Fiber coupling and field mixing of coherent free-space optical beams in satellite communications
Poliak, J.; Giggenbach, D.; Mata Calvo, R.; Bok, D.
2016-03-01
Effective coupling of the optical field from free-space to optical fiber is an essential prerequisite for modern free-space optical communications systems. It allows for easier system integration with active and passive optical fiber-coupled components as well as for efficient optical field mixing for coherent communications. While coupling into single-mode fiber provides the advantage of using low-noise erbium-doped fiber preamplifiers, its relatively small mode field diameter limits achievable fiber coupling efficiency. Coupling into multimode fiber (MMF) increases the fiber coupling efficiency while introducing other spurious effects the authors have set out to analyze. The study of free-space optical beam coupling in the context of satellite communications will be presented. Here, we assume satellite link scenarios with different elevations, which correspond to different index-of-refraction turbulence (IRT) conditions. IRT gives rise to both intensity and phase aberration of the received optical field, which then causes extended speckle patterns in the focus of the receiver telescope. The speckle field at the fiber input is calculated by means of Fourier transform of the received field. Using dedicated modelling software, study of the fiber coupling efficiency, polarization preservation and high-order mode coupling in different multi-mode fibers is carried out.
Probing WWγ and WWγγ couplings with high energy photon beams
International Nuclear Information System (INIS)
We examine the potential of a future 500 GeV linear e+e- collider for probing anomalous WWγ and WWγγ couplings in the so-called γ(γ)model, corresponding to colliding γe and γγ beams from Compton backscattering of laser light. We consider in detail the 'minimal' set (kγ, λγ) of CP conserving anomalous couplings and present first results for the CP violating 'partner' couplings (anti Kγ, anti lγ) as well. The reactions under consideration are γe → Wν, γγ → W+W- and, as a reference, also e+e- → W+W-. We discuss the impact of both circular polarization of laser photons and polarized e(anti e) beams. Photon 'beams' due to classical Bremsstrahlung are also studied for comparison. We analyze in detail, how changes of the assumed machine parameters, cuts and systematic errors affect the sensitivity to the anomalous couplings. (orig.)
Simulation of Heavy-Ion Beam Losses with the SixTrack-FLUKA Active Coupling
Hermes, Pascal; Cerutti, Francesco; Ferrari, Alfredo; Jowett, John; Lechner, Anton; Mereghetti, Alessio; Mirarchi, Daniele; Ortega, Pablo; Redaelli, Stefano; Salvachua, Belen; Skordis, Eleftherios; Valentino, Gianluca; Vlachoudis, Vasilis
2016-01-01
The LHC heavy-ion program aims to further increase the stored ion beam energy, putting high demands on the LHC collimation system. Accurate simulations of the ion collimation efficiency are crucial to validate the feasibility of new proposed configurations and beam parameters. In this paper we present a generalized framework of the SixTrack-FLUKA coupling to simulate the fragmentation of heavy-ions in the collimators and their motion in the LHC lattice. We compare heavy-ion loss maps simulated on the basis of this framework with the loss distributions measured during heavy-ion operation in 2011 and 2015.
Laser coupling of the numerous flattened Gaussian beams in the fiber-based ICF laser driver
International Nuclear Information System (INIS)
Highlights: ► The laser coupling issue in the novel fiber-based ICF laser driver is analyzed. ► The requirements for the output capabilities of the fiber laser are given which provides some hint for future research of high energy fiber laser system. -- Abstract: Fiber-based inertial confinement fusion (ICF) laser driver provides a new pathway to realize the inertial fusion energy (IFE). The feasibility of this proposal is checked from the perspective of laser coupling process in this paper. Flattened Gaussian beam (FGB) is assumed for theoretical analysis. The focusing properties of the FGB are used to obtain the requirements for a single laser beam. Based on the typical parameters of the chamber and target in ICF research, the output energy from a single fiber amplification chain is estimated to be over several hundred milli-joule. New fiber structures needs to be designed to meet the requirements
Design of an Angle Detector for Laser Beams Based on Grating Coupling
Directory of Open Access Journals (Sweden)
Weidong Zhou
2012-02-01
Full Text Available A novel angle detector for laser beams is designed in this paper. It takes advantage of grating coupling to couple the incident light into a slab waveguide; and, the incident light’s angle can be determined by reading the outputs of light detectors within the waveguide. This device offers fast-responding on-chip detection of laser beam’s angle. Compared to techniques based on quadrant photodiodes or lateral effect photodiodes, the device in this paper has far greater detectable range (up to a few degrees, to be specific. Performance of the laser angle detector in this paper is demonstrated by finite-difference-time-domain simulations. Numerical results show that, the detectable angle range can be adjusted by several design parameters and can reach [−4°, 4°]. The laser beam angle detector in this paper is expected to find various applications such as ultra-fast optical interconnects.
Numerical Verification of the Power Transfer and Wakefield Coupling in the Clic Two-Beam Accelerator
Energy Technology Data Exchange (ETDEWEB)
Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; /SLAC; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN
2011-08-19
The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its two-beam accelerator (TBA) concept envisions complex 3D structures, which must be modeled to high accuracy so that simulation results can be directly used to prepare CAD drawings for machining. The required simulations include not only the fundamental mode properties of the accelerating structures but also the Power Extraction and Transfer Structure (PETS), as well as the coupling between the two systems. Time-domain simulations will be performed to understand pulse formation, wakefield damping, fundamental power transfer and wakefield coupling in these structures. Applying SLAC's parallel finite element code suite, these large-scale problems will be solved on some of the largest supercomputers available. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel two-beam accelerator scheme.
Coupled flexural-longitudinal vibration of delaminated composite beams with local stability analysis
Szekrényes, András
2014-09-01
A novel analytical model is developed to solve the problem of free vibration of delaminated composite beams. The beam with a single delamination was modelled by six equivalent single layers by establishing the kinematic continuity in the undelaminated portion of the system. In the delaminated region the layers were captured by the traditional theories. First, Timoshenko beam theory is applied to solve the problem, then by reducing the model, the corresponding Euler-Bernoulli solution is presented. Both the free and constrained models were considered. The most important aspect of the present analysis is that the beams of the delaminated region are subjected to normal forces, as well. That is the essential reason for leading to a coupled flexural-longitudinal vibration problem. It is also concluded that delamination buckling can take place if the normal force is compressive in one of the half-periods of the vibration and reaches a critical value. The problem was also investigated experimentally by modal hammer and sweep excitation tests on beams made of E-glass/polyester in order to measure the natural frequencies and mode shapes. The comparison of the analytical and experimental results indicates the importance of the independent rotations provided by Timoshenko beams over the simple beam theory. The delamination buckling of the beams was captured based on the static stability analysis in the first step. Further results show that the problem is more complex than it was thought before, e.g., some nonlinearity, time-dependent stiffness as well as parametric excitation aspects were discovered during the present analysis.
Coupled flexural-torsional vibration band gap in periodic beam including warping effect
Institute of Scientific and Technical Information of China (English)
Fang Jian-Yu; Yu Dian-Long; Han Xiao-Yun; Cai Li
2009-01-01
The propagation of coupled flexural-torsional vibration in the periodic beam including warping effect is investigated with the transfer matrix theory.The band structures of the periodic beam,both including warping effect and ignoring warping effect,are obtained.The frequency response function of the finite periodic beams is simulated with finite element method,which shows large vibration attenuation in the frequency range of the gap as expected.The effect of warping stiffness on the band structure is studied and it is concluded that substantial error can be produced in high frequency range if the effect is ignored.The result including warping effect agrees quite well with the simulated result.
Institute of Scientific and Technical Information of China (English)
张波; Geon Joon Lee; 刘慧; 龚旗煌; Jiwon Sohn; Jaehoon Hwang; Soo Young Park; Jin-Kyung Lee; Jai-Hyung Lee; Joon-Sung Chang
2002-01-01
We have investigated the photorefractive properties of a fully functional polymer, 9-(2-Ethyl-hexyl)-3-[2-(4-methanesulfonyl-phenyl)vinyl]-9H-carbazole, using a multiline He-Ne laser. We measured the wavelength-dependent two-beam coupling coefficient, which exhibited a maximal value of 105 cm- 1 at 609 nm under an applied electric field of 84 V/μm at room temperature.
High-flux cold rubidium atomic beam for strongly-coupled cavity QED
International Nuclear Information System (INIS)
This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D+ magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 1010 atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.
High-flux cold rubidium atomic beam for strongly-coupled cavity QED
Energy Technology Data Exchange (ETDEWEB)
Roy, Basudev [Indian Institute of Science Education and Research, Kolkata (India); University of Maryland, MD (United States); Scholten, Michael [University of Maryland, MD (United States)
2012-08-15
This paper presents a setup capable of producing a high-flux continuous beam of cold rubidium atoms for cavity quantum electrodynamics experiments in the region of strong coupling. A 2D{sup +} magneto-optical trap (MOT), loaded with rubidium getters in a dry-film-coated vapor cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate greater than 2 x 10{sup 10} atoms/s. The MM-MOT provided a continuous beam with a tunable velocity. This beam was then directed through the waist of a cavity with a length of 280 μm, resulting in a vacuum Rabi splitting of more than ±10 MHz. The presence of a sufficient number of atoms in the cavity mode also enabled splitting in the polarization perpendicular to the input. The cavity was in the strong coupling region, with an atom-photon dipole coupling coefficient g of 7 MHz, a cavity mode decay rate κ of 3 MHz, and a spontaneous emission decay rate γ of 6 MHz.
Energy Technology Data Exchange (ETDEWEB)
Nakahama, M.; Gu, X.; Sakaguchi, T. [Photonics Integration System Research Center, Tokyo Institute of Technology, 4259-R2-22, Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Matsutani, A. [Semiconductor and MEMS Processing Center, Tokyo Institute of Technology, 4259-R2-22, Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ahmed, M.; Bakry, A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Koyama, F. [Photonics Integration System Research Center, Tokyo Institute of Technology, 4259-R2-22, Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)
2015-08-17
We report a high-speed electrical beam switching of vertical cavity surface emitting laser with a transverse coupled cavity. A high speed (sub-gigahertz) and large deflection angle (>30°) beam switching is demonstrated by employing the transverse mode switching. The angular switching speed of 900 MHz is achieved with narrow beam divergence of below 4° and extinction ratio of 8 dB. We also measured the near- and far-field patterns to clarify the origin of the beam switching. We present a simple one-dimensional Bragg reflector waveguide model, which well predicts the beam switching characteristic.
International Nuclear Information System (INIS)
Highlights: • A Neutronics and Thermal-hydraulics Coupled code is developed for transient analysis. • The spatial kinetics model was employed in the benchmark. • The simulation correctness of NTC accuracy demonstrated by benchmark. - Abstract: The Neutronics and Thermal-hydraulics Coupled Simulation program (NTC) is developed by FDS Team, which is a code used for transient analysis of advanced reactors. To investigate the capacity and calculation correctness of NTC for transient simulation, a benchmark on beam interruptions in an 80 MWth LBE-cooled and MOX-fuelled experimental accelerator-driven sub-critical system XADS was carried out by NTC. The benchmark on beam interruptions used in this paper was developed by the OECD/NEA Working Party on Scientific Issues in Partitioning and Transmutation (WPPT). The calculation model had the minimum phenomenological and computational complexity which concerned a simple model (single fuel channel thermal-hydraulics) of the average fuel pin corresponding to the BOL fuel condition. This benchmark was designed to investigate the temperature and power responses caused by beam interruption of different durations, which aimed at comparative assessment of NTC and other computation methods. A comparison of NTC and other ten sets of temperature and power was provided, which showed that the results had good agreement
ACE3P Computations of Wakefield Coupling in the CLIC Two-Beam Accelerator
Energy Technology Data Exchange (ETDEWEB)
Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; /SLAC; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN
2010-10-27
The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its novel two-beam accelerator concept envisions rf power transfer to the accelerating structures from a separate high-current decelerator beam line consisting of power extraction and transfer structures (PETS). It is critical to numerically verify the fundamental and higher-order mode properties in and between the two beam lines with high accuracy and confidence. To solve these large-scale problems, SLAC's parallel finite element electromagnetic code suite ACE3P is employed. Using curvilinear conformal meshes and higher-order finite element vector basis functions, unprecedented accuracy and computational efficiency are achieved, enabling high-fidelity modeling of complex detuned structures such as the CLIC TD24 accelerating structure. In this paper, time-domain simulations of wakefield coupling effects in the combined system of PETS and the TD24 structures are presented. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel CLIC two-beam accelerator scheme.
Stability of higher-order longitudinal modes in a bunched beam without mode coupling
International Nuclear Information System (INIS)
The theory of longitudinal instabilities of bunched beams was proposed by F. Sacherer. Starting from the Vlasov equation, he derived the integral equation for the perturbed distribution function. While the general method to solve the integral equation was given by Sacherer, a number of other papers discussing longitudinal bunched beam instability have also been published. Here we want to propose another formalism with which we can treat the integral equation without mode coupling for the case of a Gaussian bunch. We then generalize the formalism for the other bunch distributions, and derive a practical method to analyze the instability for the case of a parabolic bunch. While the solution of the Sacherer equation that we find is not new, we present another approach to solve it. Since the integral equation for the transverse instability is similar to that for the longitudinal instability, this formalism is also useful for the transverse case. 12 figs., 4 figs
International Nuclear Information System (INIS)
The coupling between eddy current and motion in a cantilevered beam is examined. The beam, which provides a simple model for the limiter blades of a tokamak fusion reactor, was subjected to simultaneous orthogonal time-varying and constant magnetic fields. The dynamic deformation of the beam includes two different modes: a bending mode and a torsional mode. Interaction of current with each mode and with the combined modes of vibration in described. Experimental verification of the case without torsional motion was performed with the FELIX facility at ANL. The peak deflection and stresses are much less than those predicted without consideration given to the coupling
Investigation of the thermo-optic effect in doubly coupled photonic crystal split-beam nanocavities
Lin, Tong; Tao, Jifang; Chau, Fook Siong; Deng, Jie; Zhou, Guangya; Gu, Yuandong
2016-07-01
We design and experimentally demonstrate doubly coupled photonic crystal split-beam nanocavities. The thermal response of the coupled nanocavities is characterized by controlling the device temperature: the resonant wavelengths of the odd mode (1557.28 nm) and even mode (1567.18 nm) are both redshifted linearly from 17.4 °C to 46.5 °C. The tuning ratio of the two modes is measured to be 97.4%, implying that they respond almost the same to temperature changes. Therefore, changes of the wavelength difference between this pair of modes can be applied to effectively decouple the thermo-optic effect from the optomechanical effect without on-chip temperature self-referencing. Additionally, the topmost quality-factor approaches 28 300 throughout the thermal tuning. The proposed structure paves the way for studying purely optomechanical actuations.
High frequency impedances in European XFEL
Energy Technology Data Exchange (ETDEWEB)
Dohlus, Martin; Zagorodnov, Igor; Zagorodnova, Olga
2010-06-15
The method of the optical approximation is used to estimate the high frequency impedances of different vacuum chamber transitions of the European XFEL beam line. The approximations of the longitudinal impedances are obtained in terms of simple one-dimensional integrals. The transverse impedances are written in analytical closed form. The analytical results are compared with the results obtained by numerical solution of Maxwell's equations. (orig.)
Hodges, Robert V.; Nixon, Mark W.; Rehfield, Lawrence W.
1987-01-01
A methodology was developed for the structural analysis of composite rotor blades. This coupled-beam analysis is relatively simple to use compared with alternative analysis techniques. The beam analysis was developed for thin-wall single-cell rotor structures and includes the effects of elastic coupling. This paper demonstrates the effectiveness of the new composite-beam analysis method through comparison of its results with those of an established baseline analysis technique. The baseline analysis is an MSC/NASTRAN finite-element model built up from anisotropic shell elements. Deformations are compared for three linear static load cases of centrifugal force at design rotor speed, applied torque, and lift for an ideal rotor in hover. A D-spar designed to twist under axial loading is the subject of the analysis. Results indicate the coupled-beam analysis is well within engineering accuracy.
Impedance and collective effects in the KEKB
Energy Technology Data Exchange (ETDEWEB)
Chin, Yongho [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Oide, Katsunobu
1996-08-01
This paper focuses on beam instabilities due to single-beam collective effects, impedances from various beamline elements, ion trapping, photo-electrons, and other issues in the KEKB. We will also discuss the power deposition generated by a beam in the form of the Higher-Order-Mode (HOM) losses by interacting with its surroundings. (author)
Institute of Scientific and Technical Information of China (English)
ZHANG Ping; BIAN Bao-Min; LI Zhen-Hua
2005-01-01
@@ A novel fibre-coupling zig-zag beam deflection technology is developed to investigate the attenuation process of laser-induced shock waves in air. Utilizing ordinal reflections of probe beams by a pair of parallel mirrors,a zig-zag beam field is formed, which has eleven probe beams in the horizontal plane. When a laser-induced shock wave propagates through the testing field, it causes eleven deflection signals one after another. The whole attenuation process of the shock wave in air can be detected and illuminated clearly on one experimental curve.
Impact of the number of coupling points on values of composite beams deformations
Directory of Open Access Journals (Sweden)
Tarić Mirsad
2011-01-01
Full Text Available Technological development, thanks to which high-performance materials were produced, allowed engineers to design elegant structures, which in the total load have smaller share of dead weight. All this gave an opportunity to bridge the large spans. Technological development is accompanied by the development of powerful computer software that is able to, in the phase of construction modelling, include many parameters. Thanks to that, designers have a better insight into how elements behave under load, and they are able to choose how to use material and exploit their good characteristics. Composite structures, formed by coupling of steel and concrete, rank among the modern structures. Their advantage lies in the fact that the steel part of the cross-section takes part in tensile stresses transfer, while the concrete part, because of its massiveness, takes part in compressive stress transfer. Redistribution of stresses in one composite cross-section depends on many factors. In this paper, using finite element method, the influence of number coupling points on the deformation of simply supported beam, with a composite cross-section was analyzed. The span of the beam is 5m.
Noll, Scott; Dreyer, Jason; Singh, Rajendra
2014-02-01
Structure borne vibration and noise in an automobile are often explained by representing the full vehicle as a system of elastically coupled beam structures representing the body, engine cradle and body subframe where the engine is often connected to the chassis via inclined viscoelastic supports. To understand more clearly the interactions between a beam structure and isolators, this article examines the flexural and longitudinal motions in an elastic beam with intentionally inclined mounts (viscoelastic end supports). A new analytical solution is derived for the boundary coupled Euler beam and wave equations resulting in complex eigensolutions. This system is demonstrated to be self-adjoint when the support stiffness matrices are symmetric; thus, the modal analysis is used to decouple the equations of motion and solve for the steady state, damped harmonic response. Experimental validation and computational verifications confirm the validity of the proposed formulation. New and interesting phenomena are presented including coupled rigid motions, modal properties for ideal angled roller boundaries, and relationships between coupling and system modal loss factors. The ideal roller boundary conditions when inclined are seen as a limiting case of coupled longitudinal and flexural motions. In particular, the coupled rigid body motions illustrate the influence of support stiffness coupling on the eigenvalues and eigenfunctions. The relative modal strain energy concept is used to distinguish the contribution of longitudinal and flexural deformation modes. Since the beam is assumed to be undamped, the system damping is derived from the viscoelastic supports. The support damping (for a given loss factor) is shown to be redistributed between the system modes due to the inclined coupling mechanisms. Finally, this article provides valuable insight by highlighting some technical issues a real-life designer faces when balancing modeling assumptions such as rigid or elastic
RF impedance measurement calibration
International Nuclear Information System (INIS)
The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references
Directory of Open Access Journals (Sweden)
Xiang Xu
2013-09-01
Full Text Available This paper presents a novel method to nonlinearly investigate the dynamics of the coupled axial and torsional vibrations in the circular cross section beam of the steam turbine generator using the FFT analysis. Firstly, the coupled axial and torsional vibrations of a beam are proved by equivalent law of shearing stress and different boundary conditions. Then, a nonlinear mathematical model of the coupled axial and torsional vibrations is established by the Galerkin method. Lastly, the fast Fourier transform (FFT is employed to investigate the coupled effect of the beam vibration. A practical calculation example is calculated numerically and the coupled mechanism of the beam’s axial and torsional vibrations is analyzed in detail. The analysis results show that the frequencies of the coupled response would be existed in some special orders and the coupled response frequencies are smaller than the single vibration. Since for the first time the coupled mechanism of the beam’s axial and torsional vibrations is theoretically analyzed, the findings in this work may provide directive reference for practical engineering problems in design of steam turbine generators.
Reducing the SPS Machine Impedance
Collier, Paul; Guinand, R; Jiménez, J M; Rizzo, A; Spinks, Alan; Weiss, K
2002-01-01
The SPS as LHC Injector project has been working for some time to prepare the SPS for its role as final injector for the LHC. This included major work related to injection, acceleration, extraction and beam instrumentation for the LHC beams [1]. Measurements carried out with the high brightness LHC beam showed that a major improvement of the machine impedance would also be necessary [2]. In addition to removing all lepton related components (once LEP operation ended in 2000), the decision was made to shield the vacuum system pumping port cavities. These accidental cavities had been identified as having characteristic frequencies in the 1-1.5GHz range. Since the SPS vacuum system contains roughly 1000 of these cavities, they constitute a major fraction of the machine impedance. As removal of the ports and associated bellows is not possible, transition shields (PPS) had to be designed to insert within the pumping port cavities.
Srivastava, S.K.; Ramaneti, R.; Roelse, M.; Duy Tong, H.; Vrouwe, E.X.; Brinkman, A.G.M.; Smet, de L.C.P.M.; Rijn, van C.J.M.; Jongsma, M.A.
2015-01-01
Impedance spectroscopy of cell lines on interdigitated electrodes (IDEs) is an established method of monitoring receptor-specific cell shape changes in response to certain analytes. Normally, assays are done in multiwells making it a bulky, static and single use procedure. Here, we present a biosens
An X-band high-impedance relativistic klystron amplifier with an annular explosive cathode
International Nuclear Information System (INIS)
The feasibility of employing an annular beam instead of a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated in theory and simulation. Small-signal theory analysis indicates that the optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, and beam-loaded quality factor of annular beams are all larger than the corresponding parameters of solid beams at the same beam voltage and current. An annular beam RKA and a solid beam RKA with almost the same geometric parameters are compared in particle-in-cell simulation. Output microwave power of 100 MW, gain of 50 dB, and power conversion efficiency of 42% are obtained in an annular beam RKA. The annular beam needs a 15% lower uniform guiding magnetic field than the solid beam. Our investigations demonstrate that we are able to use a simple annular explosive cathode immersed in a lower uniform magnetic field instead of a solid thermionic cathode in a complicated partially shielding magnetic field for designing high-impedance RKA, which avoids high temperature requirement, complicated electron-optical system, large area convergence, high current density, and emission uniformity for the solid beam. An equivalent method for the annular beam and the solid beam on bunching features is proposed and agrees with the simulation. The annular beam has the primary advantages over the solid beam that it can employ the immersing uniform magnetic field avoiding the complicated shielding magnetic field system and needs a lower optimum guiding field due to the smaller space charge effect
An X-band high-impedance relativistic klystron amplifier with an annular explosive cathode
Zhu, Danni; Zhang, Jun; Zhong, Huihuang; Qi, Zumin
2015-11-01
The feasibility of employing an annular beam instead of a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated in theory and simulation. Small-signal theory analysis indicates that the optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, and beam-loaded quality factor of annular beams are all larger than the corresponding parameters of solid beams at the same beam voltage and current. An annular beam RKA and a solid beam RKA with almost the same geometric parameters are compared in particle-in-cell simulation. Output microwave power of 100 MW, gain of 50 dB, and power conversion efficiency of 42% are obtained in an annular beam RKA. The annular beam needs a 15% lower uniform guiding magnetic field than the solid beam. Our investigations demonstrate that we are able to use a simple annular explosive cathode immersed in a lower uniform magnetic field instead of a solid thermionic cathode in a complicated partially shielding magnetic field for designing high-impedance RKA, which avoids high temperature requirement, complicated electron-optical system, large area convergence, high current density, and emission uniformity for the solid beam. An equivalent method for the annular beam and the solid beam on bunching features is proposed and agrees with the simulation. The annular beam has the primary advantages over the solid beam that it can employ the immersing uniform magnetic field avoiding the complicated shielding magnetic field system and needs a lower optimum guiding field due to the smaller space charge effect.
Optimized coupling of cold atoms into a fiber using a blue-detuned hollow-beam funnel
International Nuclear Information System (INIS)
We theoretically investigate the process of coupling cold atoms into the core of a hollow-core photonic-crystal optical fiber using a blue-detuned Laguerre-Gaussian beam. In contrast to the use of a red-detuned Gaussian beam to couple the atoms, the blue-detuned hollow beam can confine cold atoms to the darkest regions of the beam, thereby minimizing shifts in the internal states and making the guide highly robust to heating effects. This single optical beam is used as both a funnel and a guide to maximize the number of atoms into the fiber. In the proposed experiment, Rb atoms are loaded into a magneto-optical trap (MOT) above a vertically oriented optical fiber. We observe a gravito-optical trapping effect for atoms with high orbital momentum around the trap axis, which prevents atoms from coupling to the fiber: these atoms lack the kinetic energy to escape the potential and are thus trapped in the laser funnel indefinitely. We find that by reducing the dipolar force to the point at which the trapping effect just vanishes, it is possible to optimize the coupling of atoms into the fiber. Our simulations predict that by using a low-power (2.5 mW) and far-detuned (300 GHz) Laguerre-Gaussian beam with a 20-μm-radius core hollow fiber, it is possible to couple 11% of the atoms from a MOT 9 mm away from the fiber. When the MOT is positioned farther away, coupling efficiencies over 50% can be achieved with larger core fibers.
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede;
2014-01-01
This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not match...
Exact solutions for coupled free vibrations of tapered shear-flexible thin-walled composite beams
Piovan, Marcelo T.; Filipich, Carlos P.; Cortínez, Víctor H.
2008-09-01
In this paper, analytical solutions for the free vibration analysis of tapered thin-walled laminated-composite beams with both closed and open cross-sections are developed. The present study is based on a recently developed model that incorporates in a full form the shear flexibility. The model considers shear flexibility due to bending as well as warping related to non-uniform torsion. The theory is briefly reviewed with the aim to present the equilibrium equations, the related boundary conditions and the constitutive equations. The stacking sequences in the panels of the cross-sections are selected in order to behave according to certain elastic coupling features. Typical laminations for a box-beam such as circumferentially uniform stiffness (CUS) or circumferentially asymmetric stiffness (CAS) configurations are adopted. For open cross-sections, special laminations behaving elastically like the CAS and CUS configurations of closed sections are also taken into account. The exact values (i.e. with arbitrary precision) of frequencies are obtained by means of a generalized power series methodology. A recurrence scheme is introduced with the aim to simplify the algebraic manipulation by shrinking the number of unknown variables. A parametric analysis for different taper ratios, slenderness ratios and stacking sequences is performed. Numerical examples are also carried out focusing attention in the validation of the present theory with respect to 2D FEM computational approaches, as well as to serve as quality test and convergence test of former finite elements schemes.
Deflecting modes of the side-coupled cavity structure
International Nuclear Information System (INIS)
The deflecting modes of the 805 MHz side-coupled cavity structure with the relativistic factor 0.566 are studied. Our main concern is the dispersion properties among different configurations of side-coupling cells and their interpretations. It is shown that the ninety degree side-coupling cell configuration, so to speak, the Mickey Mouse configuration has a merit in reducing the HEM1 passband. Another concern is the magnitude of the transverse coupling impedance around the synchronization condition. It is shown that the existence of the coupling cell introduces the nonuniformity of the deflecting mode and gives different impedance relative to the beam axis and that the coupling impedance at π/10 exceeds 50 MΩ/m if the quality value of the mode is around 12000
Energy Technology Data Exchange (ETDEWEB)
Lee, Edward P.
2002-02-01
The coupled Kapchinskij-Vladimirskij (K-V) envelope equations for a charged particle beam transported by a periodic system of quadrupoles with self-consistent space charge force have previously been solved by various approximate methods, with accuracy ranging from 1% to 10%. A new method of solution is introduced here, which is based on a double expansion of the beam envelope functions in powers of the focal strength and either the beam's emittance or its dimensionless perveance. This method results in accuracy better than 0.1% for typical lattice and beam parameters when carried through one consistent level of approximation higher than employed in previous work. Several useful quantities, such as the values of the undepressed tune and the beam's perveance in the limit of vanishing emittance, are represented by very rapidly converging power series in the focal strength, with accuracy of .01% or better.
Sun, Weihua; Chen, Jun; Chen, Lujun; Wang, Jianlong; Zhang, Yongming
2016-07-01
Advanced oxidation processes (AOP) can be combined with biological treatments for recalcitrant organic pollutant decomposition. However, there has been no thorough investigation on the coupling of AOPs and membrane bioreactors (MBR) to treat polymer organic pollutants. This study proposes a new AOP that couples electron beam (EB) radiation and MBR treatment. This method was applied to treat real textile effluents containing polyvinyl alcohol (PVA). During the stable operation stage, 31 ± 7% (n = 28) COD was removed by the EB-MBR process. COD removal was enhanced to 45% at the end of the research period without process optimization. In addition, both the membrane flux and activated sludge system exhibited good stability. Only a 2% membrane flux decreased was observed after a 46 d operation period. PVA radiolysis and biofacies analysis mechanisms are also discussed. By contrast, PVA degradation using only the MBR treatment was ineffective in this study. This ineffectiveness was caused by membrane interception and floccule formation by PVA and activated sludge. PMID:27107385
Impedances of Laminated Vacuum Chambers
Energy Technology Data Exchange (ETDEWEB)
Burov, A.; Lebedev, V.; /Fermilab
2011-06-22
First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].
International Nuclear Information System (INIS)
An efficient piezoelectric smart beam finite element based on Reddy’s third-order displacement field and layerwise linear potential is presented here. The present formulation is based on the coupled polynomial field interpolation of variables, unlike conventional piezoelectric beam formulations that use independent polynomials. Governing equations derived using a variational formulation are used to establish the relationship between field variables. The resulting expressions are used to formulate coupled shape functions. Starting with an assumed cubic polynomial for transverse displacement (w) and a linear polynomial for electric potential (φ), coupled polynomials for axial displacement (u) and section rotation (θ) are found. This leads to a coupled quadratic polynomial representation for axial displacement (u) and section rotation (θ). The formulation allows accommodation of extension–bending, shear–bending and electromechanical couplings at the interpolation level itself, in a variationally consistent manner. The proposed interpolation scheme is shown to eliminate the locking effects exhibited by conventional independent polynomial field interpolations and improve the convergence characteristics of HSDT based piezoelectric beam elements. Also, the present coupled formulation uses only three mechanical degrees of freedom per node, one less than the conventional formulations. Results from numerical test problems prove the accuracy and efficiency of the present formulation. (paper)
Passive cavity laser and tilted wave laser for Bessel-like beam coherently coupled bars and stacks
Ledentsov, N. N.; Shchukin, V. A.; Maximov, M. V.; Gordeev, N. Y.; Kaluzhniy, N. A.; Mintairov, S. A.; Payusov, A. S.; Shernyakov, Yu. M.; Vashanova, K. A.; Kulagina, M. M.; Schmidt, N. Y.
2015-03-01
Ultralarge output apertures of semiconductor gain chips facilitate novel applications that require efficient feedback of the reflected laser light. Thick (10-30 μm) and ultrabroad (>1000 μm) waveguides are suitable for coherent coupling through both near-field of the neighboring stripes in a laser bar and by applying external cavities. As a result direct laser diodes may become suitable as high-power high-brightness coherent light sources. Passive cavity laser is based on the idea of placing the active media outside of the main waveguide, for example in the cladding layers attached to the waveguide, or, as in the case of the Tilted Wave Laser (TWL) in a thin waveguide coupled to the neighboring thick waveguide wherein most of the field intensity is localized in the broad waveguide. Multimode or a single vertical mode lasing is possible depending on the coupling efficiency. We demonstrate that 1060 nm GaAs/GaAlAs-based Tilted Wave Lasers (TWL) show wall-plug efficiency up to ~55% with the power concentrated in the two symmetric vertical beams having a full width at half maximum (FWHM) of 2 degrees each. Bars with pitch sizes in the range of 25-400 μm are studied and coherent operation of the bars is manifested with the lateral far field lobes as narrow as 0.1° FWHM. As the near field of such lasers in the vertical direction represents a strongly modulated highly periodic pattern of intensity maxima such lasers or laser arrays generate Bessel-type beams. These beams are focusable similar to the case of Gaussian beams. However, opposite to the Gaussian beams, such beams are self-healing and quasi non-divergent. Previously Bessel beams were generated using Gaussian beams in combination with an axicon lens or a Fresnel biprism. A new approach does not involve such complexity and a novel generation of laser diodes evolves.
Impedance and collective effects in the LHC
Energy Technology Data Exchange (ETDEWEB)
Gareyte, J. [European Organization for Nuclear Research, Geneva (Switzerland)
1996-08-01
After a review of the main LHC parameters, and a brief description of the RF and vacuum systems, the coupling impedances of the main machine elements are given, as well as the resulting thresholds for instabilities. (author)
International Nuclear Information System (INIS)
The primary objective of this study was to measure the coupling between a specific I-beam support structure, cantilevered from the infield side of the storage ring tunnel, and the storage ring tunnel/basemat. The support structure is mechanically connected to the side of the tunnel. It has the potential for a large resonant response and coupling to the storage ring basemat through its mechanical mounting or through the many pipes and ducts fastened to it. Impact excitation force was used to determine the lowest resonant frequency of the structure. Ambient vibration was used as the excitation source for studying the coupling
Beam equipment electromagnetic interaction in accelerators: simulation and experimental benchmarking
Passarelli, Andrea; Vaccaro, Vittorio Giorgio; Massa, Rita; Masullo, Maria Rosaria
One of the most significant technological problems to achieve the nominal performances in the Large Hadron Collider (LHC) concerns the system of collimation of particle beams. The use of collimators crystals, exploiting the channeling effect on extracted beam, has been experimentally demonstrated. The first part of this thesis is about the optimization of UA9 goniometer at CERN, this device used for beam collimation will replace a part of the vacuum chamber. The optimization process, however, requires the calculation of the coupling impedance between the circulating beam and this structure in order to define the threshold of admissible intensity to do not trigger instability processes. Simulations have been performed with electromagnetic codes to evaluate the coupling impedance and to assess the beam-structure interaction. The results clearly showed that the most concerned resonance frequencies are due solely to the open cavity to the compartment of the motors and position sensors considering the crystal in o...
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash;
2016-01-01
A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance...... Source (MCIS) networks to attain a high voltage gain. In addition, the proposed converter draws a continuous current from the source, and hence it is suitable for many types of renewable energy sources. The derived network expressions and theoretical analysis are finally validated experimentally...... with an example single-switch 400 W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief....
DEFF Research Database (Denmark)
Saracho, C. M.; Santos, Ilmar
2003-01-01
The analysis of dynamical response of a system built by a non-rotating structure coupled to flexible rotating beams is the purpose of this work. The effect of rotational speed upon the beam natural frequencies is well-known, so that an increase in the angular speeds leads to an increase in beam...
Yang Bing Xin; Guo, Weiming; Harkay, Katherine C; Sajaev, Vadim
2005-01-01
We present experimental studies of synchro-betatron-coupled electron beam motion in the Advanced Photon Source storage ring. We used a vertical kicker to start the beam motion. When the vertical chromaticity is nonzero, electrons with different initial synchrotron phases have slightly different betatron frequencies from the synchronous particle, resulting in a dramatic progression of bunch-shape distortion. Depending on the chromaticity and the time following the kick, images ranging from a simple vertical tilt in the bunch to more complicated twists and bends are seen with a visible light streak camera. Turn-by-turn beam position monitor data were taken as well. We found that the experimental observations are well described by the synchro-betatron-coupled equations of motion. We are investigating the potential of using the tilted bunch to generate picosecond x-ray pulses. Also note that the fast increase in vertical beam size after the kick is dominated by the internal synchro-betatron-coupled motion of the ...
Gray, Carl E., Jr.
1988-01-01
Using the Newtonian method, the equations of motion are developed for the coupled bending-torsion steady-state response of beams rotating at constant angular velocity in a fixed plane. The resulting equations are valid to first order strain-displacement relationships for a long beam with all other nonlinear terms retained. In addition, the equations are valid for beams with the mass centroidal axis offset (eccentric) from the elastic axis, nonuniform mass and section properties, and variable twist. The solution of these coupled, nonlinear, nonhomogeneous, differential equations is obtained by modifying a Hunter linear second-order transfer-matrix solution procedure to solve the nonlinear differential equations and programming the solution for a desk-top personal computer. The modified transfer-matrix method was verified by comparing the solution for a rotating beam with a geometric, nonlinear, finite-element computer code solution; and for a simple rotating beam problem, the modified method demonstrated a significant advantage over the finite-element solution in accuracy, ease of solution, and actual computer processing time required to effect a solution.
Numerical Calculations of Wake Fields and Impedances of LHC Collimators' Real Structures
Frasciello, Oscar
2015-01-01
The LHC collimators have very complicated mechanical designs including movable jaws made of higly resistive materials, ferrite materials, tiny RF contacts. Since the jaws are moved very close to the circulating beams their contribution in the overall LHC coupling impedance is dominant, with respect to other machine components. For these reasons accurate simulation of collimators' impedance becomes very important and challenging. Besides, several dedicated tests have been performed to verify correct simulations of lossy dispersive material properties, such as resistive wall and ferrites, benchmarking code results with analytical, semi-analytical and other numerical codes outcomes. Here we describe all the performed numerical tests and discuss the results of LHC collimators' impedances and wake fields calculations.
Energy Technology Data Exchange (ETDEWEB)
Hong QIn, Ronald Davidson
2011-07-18
The Courant-Snyder (CS) theory and the Kapchinskij-Vladimirskij (KV) distribution for high-intensity beams in a uncoupled focusing lattice are generalized to the case of coupled transverse dynamics. The envelope function is generalized to an envelope matrix, and the envelope equation becomes a matrix envelope equation with matrix operations that are non-commutative. In an uncoupled lattice, the KV distribution function, first analyzed in 1959, is the only known exact solution of the nonlinear Vlasov-Maxwell equations for high-intensity beams including self-fields in a self-consistent manner. The KV solution is generalized to high-intensity beams in a coupled transverse lattice using the generalized CS invariant. This solution projects to a rotating, pulsating elliptical beam in transverse configuration space. The fully self-consistent solution reduces the nonlinear Vlasov-Maxwell equations to a nonlinear matrix ordinary differential equation for the envelope matrix, which determines the geometry of the pulsating and rotating beam ellipse. These results provide us with a new theoretical tool to investigate the dynamics of high-intensity beams in a coupled transverse lattice. A strongly coupled lattice, a so-called N-rolling lattice, is studied as an example. It is found that strong coupling does not deteriorate the beam quality. Instead, the coupling induces beam rotation, and reduces beam pulsation.
International Nuclear Information System (INIS)
The Courant-Snyder (CS) theory and the Kapchinskij-Vladimirskij (KV) distribution for high-intensity beams in a uncoupled focusing lattice are generalized to the case of coupled transverse dynamics. The envelope function is generalized to an envelope matrix, and the envelope equation becomes a matrix envelope equation with matrix operations that are non-commutative. In an uncoupled lattice, the KV distribution function, first analyzed in 1959, is the only known exact solution of the nonlinear Vlasov-Maxwell equations for high-intensity beams including self-fields in a self-consistent manner. The KV solution is generalized to high-intensity beams in a coupled transverse lattice using the generalized CS invariant. This solution projects to a rotating, pulsating elliptical beam in transverse configuration space. The fully self-consistent solution reduces the nonlinear Vlasov-Maxwell equations to a nonlinear matrix ordinary differential equation for the envelope matrix, which determines the geometry of the pulsating and rotating beam ellipse. These results provide us with a new theoretical tool to investigate the dynamics of high-intensity beams in a coupled transverse lattice. A strongly coupled lattice, a so-called N-rolling lattice, is studied as an example. It is found that strong coupling does not deteriorate the beam quality. Instead, the coupling induces beam rotation, and reduces beam pulsation.
Development of a current monitor using a negative impedance circuit
International Nuclear Information System (INIS)
We developed a beam current transformer which appropriates for monitoring beam of an accelerator having operating period of a few seconds. The beam monitor is a new type CT which can measure DC component of beam using a negative impedance circuit. In this report, we describe stability of a time constant, temperature and frequency characteristic of the CT. (author)
Summary of the impedance working group
International Nuclear Information System (INIS)
The impedance working group concentrated on the LHC design during the workshop. They look at the impedance contributions of liner, beam position monitors, shielded bellows, experimental chambers, superconducting cavities, recombination chambers, space charge, kickers, and the resistive wall. The group concluded that the impedance budgeting and the conceptual designs of the vacuum chamber components looked basically sound. It also noted, not surprisingly, that a large amount of studies are to be carried out further, and it ventured to give a partial list of these studies
International Nuclear Information System (INIS)
We derive nonlinear governing equations without assuming that the beam is inextensible. The derivation couples the equations that govern a weak electric motor, which is used to rotate the base of the beam, to those that govern the motion of the beam. The system is considered non-ideal in the sense that the response of the motor to an applied voltage and the motion of the beam must be obtained interactively. The moment that the motor exerts on the base of the beam cannot be determined without solving for the motion of the beam
Energy Technology Data Exchange (ETDEWEB)
Fenili, André; Lopes Rebello da Fonseca Brasil, Reyolando Manoel [Universidade Federal do ABC (UFABC), Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS) / Aerospace Engineering Santo André, São Paulo (Brazil); Balthazar, José M., E-mail: jmbaltha@gmail.com [Universidade Federal do ABC (UFABC), Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS) / Aerospace Engineering Santo André, São Paulo, Brazil and Universidade Estadual Paulista, Faculdade de Engenharia Mec and #x00E (Brazil); Francisco, Cayo Prado Fernandes [Universidade Federal do ABC (UFABC), Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS) / Aerospace Engineering Santo André, São Paulo, Brazil and Instituto de Aeronáutica e Espaço, Departamento de (Brazil)
2014-12-10
We derive nonlinear governing equations without assuming that the beam is inextensible. The derivation couples the equations that govern a weak electric motor, which is used to rotate the base of the beam, to those that govern the motion of the beam. The system is considered non-ideal in the sense that the response of the motor to an applied voltage and the motion of the beam must be obtained interactively. The moment that the motor exerts on the base of the beam cannot be determined without solving for the motion of the beam.
The Aberdeen Impedance Imaging System.
Kulkarni, V; Hutchison, J M; Mallard, J R
1989-01-01
The Aberdeen Impedance Imaging System is designed to reconstruct 2 dimensional images of the average distribution of the amplitude and phase of the complex impedance within a 3 dimensional region. The system uses the four electrode technique in a 16 electrode split-array. The system hardware consists of task-orientated electronic modules for: driving a constant current, multiplexing the current drive, demultiplexing peripheral voltages, differential amplification, phase sensitive detection and low-pass filtration, digitisation with a 14 bit analog to digital converter (ADC), and -control logic for the ADC and multiplexors. A BBC microprocessor (Master series), initiates a controlled sequence for the collection of a number of data sets which are averaged and stored on disk. Image reconstruction is by a process of convolution-backprojection similar to the fan-beam reconstruction of computerised tomography and is also known as Equipotential Backprojection. In imaging impedance changes associated with fracture healing the changes may be large enough to allow retrieval of both the amplitude and phase of the complex impedance. Sequential imaging of these changes would necessitate monitoring electronic and electrode drift by imaging an equivalent region of the contralateral limb. Differential images could be retrieved when the image of the normal limb is the image template. Better characterisation of tissues would necessitate a cleaner retrieval of the quadrature signal. PMID:2742979
International Nuclear Information System (INIS)
Fluctuating coupling conditions cause a changing flaw detection sensitivity during automatic ultrasonic inspections. The coupling gap has a strong influence. In this presentation the influence of the coupling gap on the sound transmission for inclined incidence is discussed. The fluctuations of transmission are depending on the used material (probe wedge, coupling liquid, test object), the thickness of the gap and the pulse form. A theoretical modell and experimental results concerning the influence of the coupling gap are described. (orig.)
Xiang, Jin; Li, Jinxiang; Li, Hui; Zhang, Chengyun; Dai, Qiaofeng; Tie, Shaolong; Lan, Sheng
2016-05-30
A metasurface composed of regularly arranged silicon (Si) nanospheres (NSs) with coupling was investigated both theoretically and numerically based on the Mie theory, the simple Lorentz line shape model and the finite-difference time-domain technique. By deliberately controlling the coupling strength between Si NSs through the design of the lattice constants of a rectangular lattice, polarization beam splitters, converters and analyzers with good performance can be successfully constructed. A square lattice as well as a large incidence angle was employed to build the polarization beam splitters and converters. At an incidence angle of 80°, the polarization beam splitters can completely reflect the s-polarized light and transmit the p-polarized light in a wavelength region of 510-620 nm. For a circularly polarized light incident on the polarization converters, one can get s-polarized light in the reflection direction and p-polarized light in the transmission direction. For the polarization beam analyzers, a rectangular lattice with deliberately chosen lattice constants was employed and the transmissivity of a linearly polarized light can be continuously adjusted from 0 to ~0.90 by simply rotating the metasurface. We revealed that the broadening of either the electric dipole resonance or the magnetic dipole resonance or both of them, which is induced by the asymmetric coupling of Si NSs, is responsible for the modification in the transmissivity spectrum of the metasurface. Our findings provide a guideline for designing photonic devices based on the metasurfaces composed of Si NSs with controllable coupling strength. PMID:27410070
Directory of Open Access Journals (Sweden)
Alakhib Ibrahim Abdelbary
2016-07-01
Full Text Available In this work a simple double beam spectrophotometer detector for the nucleic acid detection has been designed. The developed system contains photodiodes as a sensor, logarithamatic transimpedance amplifier circuit and filter circuit.The developed prototype design accuracy is validated by running a RNA sample and the result shows that our simplified developed setup detects the present of RNA in the sample.
Lauer, Christian; König, Harald; Grönninger, Günther; Hein, Sebastian; Gomez-Iglesias, Alvaro; Furitsch, Michael; Maric, Josip; Kissel, Heiko; Wolf, Paul; Biesenbach, Jens; Strauss, Uwe
2012-03-01
The impact of new direct-diode and fiber laser systems on industrial manufacturing drives the demand for highbrightness diode laser pump sources suitable for simple fiber coupling with high efficiency. Within the German funded project HEMILAS laser mini-bars with different bar geometries and small fill factors were investigated. We present results on 9xx nm bars with tailored beam parameter products for simplified coupling to fibers with core diameters of 200μm and 300μm with a numerical aperture of 0.22 and compare beam quality parameters, brightness, conversion efficiency, and thermal performance of different bar designs. Optimized epitaxy structures yield conversion efficiency maxima above 66%. The slow axis divergence angle of mini-bars with a fill factor of 10% featuring five 100μm wide and 4mm long emitters based on this epitaxy structure stays below 7°, which corresponds to a beam parameter product of 15mm mrad, up to very high output power of over 45W. This result was achieved for mounting on actively cooled submounts using hard solder. A similar bar with 5mm cavity length and using soft soldering reached an output power of 60W at the same beam parameter product. At 4mm cavity length, no COMD failures were observed up to currents exceeding the thermal rollover and the maximum output cw power was 95W.
Impedance Localization Measurements using AC Dipoles in the LHC
Biancacci, Nicolo; Papotti, Giulia; Persson, Tobias; Salvant, Benoit; Tomás, Rogelio
2016-01-01
The knowledge of the LHC impedance is of primary importance to predict the machine performance and allow for the HL-LHC upgrade. The developed impedance model can be benchmarked with beam measurements in order to assess its validity and limit. This is routinely done, for example, moving the LHC collimator jaws and measuring the induced tune shift. In order to localize possible unknown impedance sources, the variation of phase advance with intensity between beam position monitors can be measured. In this work we will present the impedance localization measurements performed at injection in the LHC using AC dipoles as exciter as well as the underlying theory.
Wakefield and impedance studies of a liner using MAFIA
Energy Technology Data Exchange (ETDEWEB)
Chou, W.; Barts, T.
1993-03-01
The liner is a perforated beam tube that is coaxial with an outer bore tube. The 3D code MAFIA (version 3.1) is used to study the wakefields, impedances, and resonances of this structure. The short-range wakes and low-frequency (below the cutoff) impedances are in agreement with the theoretical model. The long-range wakes and high-frequency resonances are associated with the distribution of the holes (or slots). The dependence of the impedance on the size, shape, and pattern of the holes (or slots) is studied. The impact of the liner impedance on the Superconducting Super Collider impedance budget is discussed.
Wakefield and impedance studies of a liner using MAFIA
Energy Technology Data Exchange (ETDEWEB)
Chou, W.; Barts, T. (SSC Laboratory, Dallas, Texas 75237 (United States))
1993-12-25
The liner is a perforated beam tube which is coaxial with an outer bore tube. The 3D code MAFIA version 3.1 is used to study the wakefields, impedances, and resonances of this structure. The short range wakes and low frequency (below the cutoff) impedances are in agreement with the theoretical model. The long range wakes and high frequency resonances are associated with the distribution of the holes (or slots). The dependence of the impedance on the size, shape, and pattern of the holes (or slots) is studied. The impact of the liner impedance on the SSC impedance budget is discussed.
Wakefield and impedance studies of a liner using MAFIA
Chou, W.; Barts, T.
1993-12-01
The liner is a perforated beam tube which is coaxial with an outer bore tube. The 3D code MAFIA version 3.1 is used to study the wakefields, impedances, and resonances of this structure. The short range wakes and low frequency (below the cutoff) impedances are in agreement with the theoretical model. The long range wakes and high frequency resonances are associated with the distribution of the holes (or slots). The dependence of the impedance on the size, shape, and pattern of the holes (or slots) is studied. The impact of the liner impedance on the SSC impedance budget is discussed.
Line Impedance Estimation Using Active and Reactive Power Variations
DEFF Research Database (Denmark)
Timbus, Adrian Vasile; Rodriguez, Pedro; Teodorescu, Remus;
2007-01-01
This paper proposes an estimation method of power system impedance based on power variations caused by a distributed power generation system (DPGS) at the point of common coupling (PCC). The proposed algorithm is computationally simple and uses the voltage variations at the point of common coupling...... (PCC) caused by the variations of the power delivered to utility network to derive the value of grid impedance. Accurate estimation of both resistive and inductive part of the impedance is obtained, as the results presented show....
Study of coupled-bunch collective effects in the ALS
International Nuclear Information System (INIS)
We present an overview of the calculated longitudinal and transverse coupled-bunch (CB) growth rates using the measured RF cavity higher order mode (HOM) impedance for the Advanced Light Source (ALS), a 1.5 GeV electron storage ring for producing synchrotron radiation. We also describe a visual method of representing the effective beam impedance and corresponding growth rates which is especially useful for understanding the dependence of growth rate on HOM frequency and Q, for determining the requirements of the CB feedback system, and for interpreting measured beam spectra
Indian Academy of Sciences (India)
V Mantha; A K Mohanty; P Satyamurthy
2007-02-01
BARC has recently proposed a one-way coupled ADS reactor. This reactor requires typically ∼ 1 GeV proton beam with 2 mA of current. Approximately 8 kW of heat is deposited in the window of the target. Circulating liquid metal target (lead/lead-bismuth-eutectic) has to extract this heat and this is a critical R&D problem to be solved. At present there are very few accelerators, which can give few mA and high-energy proton beam. However, accelerators with low energy and hundreds of micro-ampere current are commercially available. In view of this, it is proposed in this paper to simulate beam window heating of ∼ 8 kW in the target with low-energy proton beam. Detailed thermal analysis in the spallation and window region has been carried out to study the capability of heat extraction by circulating LBE for a typical target loop with a proton beam of 30 MeV energy and current of 0.267 mA. The heat deposition study is carried out using FLUKA code and flow analysis by CFD code. The detailed analysis of this work is presented in this paper.
Rotor damage detection by using piezoelectric impedance
Qin, Y.; Tao, Y.; Mao, Y. F.
2016-04-01
Rotor is a core component of rotary machinery. Once the rotor has the damage, it may lead to a major accident. Thus the quantitative rotor damage detection method based on piezoelectric impedance is studied in this paper. With the governing equation of piezoelectric transducer (PZT) in a cylindrical coordinate, the displacement along the radius direction is derived. The charge of PZT is calculated by the electric displacement. Then, by the use of the obtained displacement and charge, an analytic piezoelectric impedance model of the rotor is built. Given the circular boundary condition of a rotor, annular elements are used as the analyzed objects and spectral element method is used to set up the damage detection model. The Electro-Mechanical (E/M) coupled impedance expression of an undamaged rotor is deduced with the application of a low-cost impedance test circuit. A Taylor expansion method is used to obtain the approximate E/M coupled impedance expression for the damaged rotor. After obtaining the difference between the undamaged and damaged rotor impedance, a rotor damage detection method is proposed. This method can directly calculate the change of bending stiffness of the structural elements, it follows that the rotor damage can be effectively detected. Finally, a preset damage configuration is used for the numerical simulation. The result shows that the quantitative damage detection algorithm based on spectral element method and piezoelectric impedance proposed in this paper can identify the location and the severity of the damaged rotor accurately.
Laser cooled ion beams and strongly coupled plasmas for precision experiments
International Nuclear Information System (INIS)
This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C3+ ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged 24Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)
Belova, E V; Gorelenkov, N N; Fredrickson, E D; Tritz, K; Crocker, N A
2015-07-01
An energy-channeling mechanism is proposed to explain flattening of the electron temperature profiles at a high beam power in the beam-heated National Spherical Torus Experiment (NSTX). Results of self-consistent simulations of neutral-beam-driven compressional Alfvén eigenmodes (CAEs) in NSTX are presented that demonstrate strong coupling of CAEs to kinetic Alfvén waves at the Alfvén resonance location. It is suggested that CAEs can channel energy from the beam ions to the location of the resonant mode conversion at the edge of the beam density profile, modifying the energy deposition profile. PMID:26182100
Single shot laser flash photolysis with a fibre-coupled reference beam monitor.
Li, Heng; van 't Hag, Leonie; Yousef, Yaser A; Melø, T B; Razi Naqvi, K
2013-02-01
In the standard nanosecond laser photolysis method for kinetic studies, a Q-switched laser generates transient species, and absorption spectrophotometry provides a measure of their concentrations. The sample is placed between the monitoring source (a pulsed xenon arc or a flash lamp) and a monochromator, and a photomultiplier tube (PMT) is used for measuring the intensity of the light leaving the exit slit of the monochromator. With this (single-beam) arrangement, the laser-induced change in the absorbance of the sample, ΔA, can be calculated only if the intensity of the monitoring beam remains constant during the time interval of interest. When this condition is not fulfilled, a second measurement of the PMT output is made after blocking the path of the laser beam, but shot-to-shot variations in the output of the monitoring source vitiate the analysis when ΔA is small. To overcome this problem, double-beam versions were developed in the last century, but the single-beam version still enjoys greater popularity. With a view to making the double-beam method easily implementable, some simple modifications are introduced, which permit the conversion of an existing laser kinetic spectrometer into a double-beam variant (with one or two monochromators). PMID:22990442
Directory of Open Access Journals (Sweden)
Mohammad Johari Ibahim
Full Text Available BACKGROUND: High-dose synchrotron microbeam radiation therapy (MRT has shown the potential to deliver improved outcomes over conventional broadbeam (BB radiation therapy. To implement synchrotron MRT clinically for cancer treatment, it is necessary to undertake dose equivalence studies to identify MRT doses that give similar outcomes to BB treatments. AIM: To develop an in vitro approach to determine biological dose equivalence between MRT and BB using two different cell-based assays. METHODS: The acute response of tumour and normal cell lines (EMT6.5, 4T1.2, NMuMG, EMT6.5ch, 4T1ch5, SaOS-2 to MRT (50-560 Gy and BB (1.5-10 Gy irradiation was investigated using clonogenic and real time cell impedance sensing (RT-CIS/xCELLigence assays. MRT was performed using a lattice of 25 or 50 µm-wide planar, polychromatic kilovoltage X-ray microbeams with 200 µm peak separation. BB irradiations were performed using a Co60 teletherapy unit or a synchrotron radiation source. BB doses that would generate biological responses similar to MRT were calculated by data interpolation and verified by clonogenic and RT-CIS assays. RESULTS: For a given cell line, MRT equivalent BB doses identified by RT-CIS/xCELLigence were similar to those identified by clonogenic assays. Dose equivalence between MRT and BB were verified in vitro in two cell lines; EMT6.5ch and SaOS-2 by clonogenic assays and RT-CIS/xCELLigence. We found for example, that BB doses of 3.4±0.1 Gy and 4.40±0.04 Gy were radiobiologically equivalent to a peak, microbeam dose of 112 Gy using clonogenic and RT-CIS assays respectively on EMT6.5ch cells. CONCLUSION: Our data provides the first determination of biological dose equivalence between BB and MRT modalities for different cell lines and identifies RT-CIS/xCELLigence assays as a suitable substitute for clonogenic assays. These results will be useful for the safe selection of MRT doses for future veterinary and clinical trials.
Study of high impedance magnetic alloy core
International Nuclear Information System (INIS)
J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) and Main Ring (MR) employ RF cavities loaded with Magnetic Alloy (MA) cores to generate a high field gradient. The MA core shunt impedance Rp is a key parameter to increase the beam power. To achieve the high shunt impedance Rp, we increased the filling factor by a strong winding tension. As a result, the shunt impedance Rp was reduced in despite of the filling factor increase because the strong winding tension deteriorates the MA core magnetic properties significantly. On the other hand, the MA core with thin ribbons and the MA core that is magnetized by the rotation process show the high permeability in the accelerating frequency region, and those MA cores show the high shunt impedance Rp consequently. (author)
Estimate of the longitudinal and transverse impedances of the main ring in the TeV I project
International Nuclear Information System (INIS)
To guarantee the successful performance of the Main Ring in Tevatron I, its stability limits and impedances have to be estimated and controlled. The impedances of the Main Ring are estimated, considering contributions from the bellows, beam position monitors, wall resistivity, kickers and Lambertsons. The estimations of the contributions to the longitudinal and transverse impedances are tabulated and plotted. The stability limits for the worst situation are also tabulated for comparison. The slow-growing single bunch instability caused by longitudinal mode coupling is found to be safe. The corresponding instability caused by transverse mode coupling is not. The fast-growing longitudinal microwave instability is found to be driven by the sharp resonances of the bellows and beam monitors and may be the broad resonances of the Lambertsons also. The fast-growing transverse microwave instability is found to be safe. It is found that, to have stability, the bellows have to be shielded and the beam monitors terminated at the ends instead of the center. The slow-growing transverse mode coupling is found to be curable by feedback. 6 tabs., 7 figs
Demonstration of beam steering via dipole-coupled plasmonic spiral antenna
Guanghao Rui; Abeysinghe, Don C.; Nelson, Robert L.; Qiwen Zhan
2013-01-01
Optical antennas have been utilized to tailor the emission properties of nanoscale emitters in terms of the intensity, directivity and polarization. In this letter, we further explore the capability of beam steering via the use a spiral plasmonic structure as a transmitting antenna. According to both numerical simulation and experimental observations, the beaming direction can be steered through introducing a displacement of the feeding point to the spiral antenna from the geometrical center....
Impedance model for nanostructures
Directory of Open Access Journals (Sweden)
R. S. Akhmedov
2007-06-01
Full Text Available The application of the impedance model for nanoelectronic quantum-mechanical structures modelling is described. Characteristics illustrating the efficiency of the model are presented.
Impedance simulation for LEReC booster cavity transformed from ERL gun cavity
Energy Technology Data Exchange (ETDEWEB)
Liu, Chuyu [Brookhaven National Lab. (BNL), Upton, NY (United States)
2015-11-24
Wake impedance induced energy spread is a concern for the low energy cooling electron beam. The impedance simulation of the booster cavity for the LEReC projection is presented in this report. The simulation is done for both non-relativistic and ultra-relativistic cases. The space charge impedance in the first case is discussed. For impedance budget consideration of the electron machine, only simulation of the geometrical impedance in the latter case is necessary since space charge is considered separately.
International Nuclear Information System (INIS)
The fundamental and practical aspects are described for extracting ions from atmospheric pressure plasma sources into an analytical mass spectrometer. Methodologies and basic concepts of inductively coupled plasma mass spectrometry (ICP-MS) are emphasized in the discussion, including ion source, sampling interface, supersonic expansion, slumming process, ion optics and beam focusing, and vacuum considerations. Some new developments and innovative designs are introduced. The plasma extraction process in ICP-MS was investigated by Langmuir measurements in the region between the skimmer and first ion lens. Electron temperature (Te) is in the range 2000--11000 K and changes with probe position inside an aerosol gas flow. Electron density (ne) is in the range 108--1010-cm at the skimmer tip and drops abruptly to 106--108 cm-3 near the skimmer tip and drops abruptly to 106--108 cm-3 downstream further behind the skimmer. Electron density in the beam leaving the skimmer also depends on water loading and on the presence and mass of matrix elements. Axially resolved distributions of electron number-density and electron temperature were obtained to characterize the ion beam at a variety of plasma operating conditions. The electron density dropped by a factor of 101 along the centerline between the sampler and skimmer cones in the first stage and continued to drop by factors of 104--105 downstream of skimmer to the entrance of ion lens. The electron density in the beam expansion behind sampler cone exhibited a 1/z2 intensity fall-off (z is the axial position). An second beam expansion originated from the skimmer entrance, and the beam flow underwent with another 1/z2 fall-off behind the skimmer. Skimmer interactions play an important role in plasma extraction in the ICP-MS instrument
Directory of Open Access Journals (Sweden)
M. Sanbi
2014-01-01
Full Text Available Smart structures with integrated sensors, actuators, and control electronics are of importance to the next generation high-performance structural systems. In this study, thermopiezoelastic characteristics of piezoelectric beam continua are studied and applications of the theory to active structures in sensing and optimal control are discussed. Using linear thermopiezoelastic theory and Timoshenko assumptions, a generic thermopiezoelastic theory for piezolaminated composite beam is derived. Finite element equations for the thermopiezoelastic media are obtained by using the linear constitutive equations in Hamilton's principle together with the finite element approximations. The structure consists of a modeling of cantilevered piezolaminated Timoshenko beam with integrated thermopiezoelectric elements between two aluminium layers. The structure is modelled analytically and then numerically and the results of simulations are presented in order to visualize the states of their dynamics and the state of control. The optimal control LQG accompanied by the Kalman filter is applied. The effects of thermoelastic and pyroelectric couplings on the dynamics of the structure and on the control procedure are studied and discussed. We show that the control procedure cannot be perturbed by applying a thermal gradient and the control can be applied at any time during the period of vibration of the beam.
Explicit Expressions of Impedances and Wake Functions
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.; /Fermilab; Bane, K,; /SLAC
2012-06-11
Sections 3.2.4 and 3.2.5 of the Handbook of Accelerator Physics and Engineering on Landau damping are combined and updated. The new addition includes impedances and wakes for multi-layer beam pipe, optical model, diffraction model, and cross-sectional transition.
Explicit expressions of impedances and wake functions
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.; /Fermilab; Bane, K,; /SLAC
2010-10-01
Sections 3.2.4 and 3.2.5 of the Handbook of Accelerator Physics and Engineering on Landau damping are combined and updated. The new addition includes impedances and wakes for multi-layer beam pipe, optical model, diffraction model, and cross-sectional transition.
Laser cooled ion beams and strongly coupled plasmas for precision experiments
Energy Technology Data Exchange (ETDEWEB)
Bussmann, Michael
2008-03-17
This cumulative thesis summarizes experimental and theoretical results on cooling of ion beams using single-frequency, single-mode tabletop laser systems. It consists of two parts. One deals with experiments on laser-cooling of ion beams at relativistic energies, the other with simulations of stopping and sympathetic cooling of ions for precision in-trap experiments. In the first part, experimental results are presented on laser-cooling of relativistic C{sup 3+} ion beams at a beam energy of 122 MeV/u, performed at the Experimental Storage Ring (ESR) at GSI. The main results presented in this thesis include the first attainment of longitudinally space-charge dominated relativistic ion beams using pure laser-cooling. The second part lists theoretical results on stopping and sympathetic cooling of ions in a laser-cooled one-component plasma of singly charged {sup 24}Mg ions, which are confined in a three-dimensional harmonic trap potential. (orig.)
Yang, Xi
2015-01-01
We propose a method to simultaneously correct linear optics errors and linear coupling for storage rings using turn-by-turn (TbT) beam position monitor (BPM) data. The independent component analysis (ICA) method is used to isolate the betatron normal modes from the measured TbT BPM data. The betatron amplitudes and phase advances of the projections of the normal modes on the horizontal and vertical planes are then extracted, which, combined with dispersion measurement, are used to fit the lattice model. The fitting results are used for lattice correction. The method has been successfully demonstrated on the NSLS-II storage ring.
Diffractive beam shaping, tracking and coupling for wave-guided optical waveguides (WOWs)
DEFF Research Database (Denmark)
Villangca, Mark Jayson; Bañas, Andrew Rafael; Aabo, Thomas; Palima, Darwin; Glückstad, Jesper
2014-01-01
We have previously proposed and demonstrated the targeted-light delivery capability of wave-guided optical waveguides (WOWs). The full strength of this structure-mediated paradigm can be harnessed by addressing multiple WOWs and manipulating them to work in tandem. We propose the use of diffractive...... techniques to create multiple focal spots that can be coupled into light manipulated WOWs. This is done by using a spatial light modulator to project the necessary phase to generate the multiple coupling light spots. We incorporate a diffractive setup in our Biophotonics Workstation (BWS) and demonstrate...... holographic shaping, tracking of light in 3D with the purpose of coupling light in the WOWs....
Potential energy savings with personalized ventilation coupled with passive chilled beams
DEFF Research Database (Denmark)
Lyubenova, Velina S.; Holsøe, Jan W.; Melikov, Arsen Krikor
2011-01-01
distribution used today. The potential of PV for energy saving has been studied little. In this study, the energy saving potential of desk mounted PV in conjunction with either mixing ventilation or a passive chilled beam system is compared to mixing ventilation alone by means of computer simulations. An open...... 20% (and up to 40% when extending the temperature in the room by 2 °C above the upper limit recommended in the standards) compared to mixing ventilation only. When PV was combined with passive chilled beams, the reduction of the supplied air was up to 80%. This ventiltion strategy may lead to energy...
Saleh, M. A.; Evans, D. R.; Allen, A. S.; Bunning, T. J.; Guha, S.
2002-03-01
By fitting the experimental results to a theoretical analysis of two-beam coupling including diffraction effects [1], the photorefractive gain as well the dark current irradiance has been evaluated. Crystals with a transparent conductive coating were used to reduce grating writing instabilities; instabilities as well as multiple reflection effects were also eliminated by AR (anti-reflection) coating the crystal surfaces [2]. [1] G. Cook, D. C. Jones, C. J. Finnan, L. L. Taylor, T. W. Vere, and J. P. Duignan, Materials Research Society Symposium Proceedings 597 (2000) 263-274. [2] D. R. Evans, S. A. Basun, M. A. Saleh, T. P. Pottenger, G. Cook, T. J. Bunning, and S. Guha, "Elimination of Photorefractive Grating Writing Instabilities in Iron-doped Lithium Niobate," Submitted to IEEE J. Quantum Electronics. Dec. 2001.
Nonlinear beam-beam resonances
International Nuclear Information System (INIS)
Head-on collisions of bunched beams are considered, assuming the two colliding beams have opposite charges. A few experimental observations are described. The single resonance analysis is developed that is applicable to the strong-weak case of the beam-beam interaction. In this case, the strong beam is unperturbed by the beam-beam interaction; motions of the weak beam particles are then analyzed in the presence of the nonlinear electromagnetic force produced by the strong beam at the collision points. The coherent motions of the two coupled strong beams are shown to exhibit distinct nonlinear resonance behavior. 16 refs., 22 figs
Energy Technology Data Exchange (ETDEWEB)
Groote, S. [Tartu Uelikool, Loodus- ja Tehnoloogiateaduskond, Fueuesika Instituut, Tartu (Estonia); Institut fuer Physik der Johannes-Gutenberg-Universitaet, Mainz (Germany); Liivat, H.; Ots, I.; Sepp, T. [Tartu Uelikool, Loodus- ja Tehnoloogiateaduskond, Fueuesika Instituut, Tartu (Estonia)
2010-03-15
In searching for indications of new-physics scalar particle and unparticle couplings in e{sup +}e{sup -}{yields}t anti t, we consider the role of transversely polarized initial beams at e{sup +}e{sup -} colliders. By using a general relativistic spin density matrix formalism for describing the particles spin states, we find analytical expressions for the differential cross section of the process with t or anti t polarization measured, including the anomalous coupling contributions. Thanks to the transversely polarized initial beams these contributions are first order anomalous coupling corrections to the Standard Model (SM) contributions. We present and analyze the main features of the SM and anomalous coupling contributions. We show how differences between SM and anomalous coupling contributions provide means to search for anomalous coupling manifestations at future e{sup +}e{sup -} linear colliders. (orig.)
Turk Cakir, I; Tasci, A T; Cakir, O
2016-01-01
We study the anomalous WWγ and WWZ couplings by calculating total cross sections of two processes at the LHeC with electron beam energy Ee=140 GeV and the proton beam energy Ep=7 TeV, and at the FCC-ep collider with the polarized electron beam energy Ee=80 GeV and the proton beam energy Ep=50 TeV. At the LHeC with electron beam polarization, we obtain the results for the difference of upper and lower bounds as (0.975, 0.118) and (0.285, 0.009) for the anomalous (∆κγ, λγ) and (∆κz, λz) couplings, respectively. As for FCC-ep collider, these bounds are obtained as (1.101, 0.065) and (0.320, 0.002) at an integrated luminosity of Lint=100 fb-1.
International Nuclear Information System (INIS)
The new approach of an e-beam initiating of chemical reactions in polymers in molten state results in some innovative results. High temperature, intensive macromolecular mobility and the absence of any crystallinity are some reasons for achieving unexpected structures, processing behaviour and properties changes in such treated thermoplastics and rubbers. Examples are a much more effective crosslinking of polyethylene and special rubbers, long chain branching of polypropylene or a partial crosslinking of polysulfone. Additionally, most of these modification effects are also achievable by a direct coupling of electron beam irradiation and conventional polymer extrusion processing for a continuous polymer modification in molten state. For realizing this unique processing technique a special MOBILE RADIATION FACILITY (MOBRAD1/T) was designed, constructed and manufactured in the IPF Dresden at which a lab-scale single screw extruder was adapted direct to an electron beam accelerator to realize a prompt irradiation of extruded polymer melt profiles before there solidification. Surprisingly, as a result of these short-time-melt reactions some effective and new polymer modification effects were found and will be presented
Low impedance kicker for high intensity accelerator
International Nuclear Information System (INIS)
A kicker magnet is one of the most important components in a synchrotron. To kick the beam from injection line to synchrotron orbit or opposite direction, a ferrite material is used to achieve a fast rise time. In case of a high intensity accelerator, the material is heated by beam current. Sometimes, it is reported that characteristic of material is changed when the material reaches Curie temperature. In this paper, we propose a low impedance kicker which consists of thin magnetic alloy ribbon. The structure of the new kicker is suitable to avoid to receive the beam effects. (author)
Rui, Guanghao; Nelson, Robert L; Zhan, Qiwen
2012-08-13
We analytically and numerically study the emission properties of an electric dipole coupled to a plasmonic spiral structure with different pitch. As a transmitting antenna, the spiral structure couples the radiation from the electric dipole into circularly polarized emitted photons in the far field. The spin carried by the emitted photons is determined by the handedness of the spiral antenna. By increasing the spiral pitch in the unit of surface plasmon wavelength, these circularly polarized photons also gain orbital angular momentum with different topological charges. This phenomenon is attributed to the presence of a geometric phase arising from the interaction of light from point source with the anisotropic spiral structure. The circularly polarized vortex emission from such optically coupled spiral antenna also has high directivity, which may find important applications in quantum optical information, single molecule sensing, and integrated photonic circuits. PMID:23038521
DEFF Research Database (Denmark)
Friis, Lars; Ohlrich, Mogens
2005-01-01
distribution of motion displacements in each wave type. This is used for calculating the spatial variation of the forced harmonic responses of a semi-infinite periodic structure to point excitations by a longitudinal force and by a moment. Numerical simulations reveal the complicated wave coupling phenomena......In this paper we investigate the coupling of flexural and longitudinal wave motions in a waveguide with structural side branches attached at regular intervals. The analysis is based on periodic structure theory, and considers wave transmission in a fully tricoupled and semidefinite periodic...
A coupled bunch instability due to beam-photoelectron interactions in KEKB-LER
Energy Technology Data Exchange (ETDEWEB)
Ohmi, Kazuhito [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)
1996-08-01
LER of KEKB is designed to storage the positron beam of 2.6 A with multibunch operation. Nb = 3.3 x 10{sup 10} positrons are filled in a bunch and the bunch passes every 2ns through a beam chamber. The photoelectron instability may be serious for KEKB-LER. We consider a motion of photoelectrons produced by a bunch with a computer simulation technic. A cylindrical chamber with a diameter of 10 cm was used as a model chamber. About 15 times of the photoelectrons were produced by a bunch. The wake force was calculated for the loading bunches with displacements of 0.5 mm and 1 mm. The wake characteristics seems to be caused by the trapped electrons kicked by the loading bunch. The wake was saturated with the loading displacement of 0.5 mm. We obtained a growth rate by the wake force. It is very high rate, 2500s{sup -1} which exceeds damping rates of various mechanism, radiation, head-tail and feedback. Perhaps it is essential to remove the photoelectrons around the positron beam explicitly. If we apply magnetic field fo about 20 G, the growth rate will be reduced. (S.Y.)
Report on single beam stability - coherent effects
International Nuclear Information System (INIS)
Group 1A was concerned with single beam stability, coherent effects. Theory is available. Most of the material for this work was drawn from F.J. Sacherer theory which has been left in reasonably good shape in the sense that given any coupling impedance, its effect on the beam can be estimated. The EBI computer program was extensively used in this respect. We still lack thorough knowledge of the SPS coupling impedance. Accordingly our results rest on a model. This model should be too unrealistic since it originates from various data of the SPS and other machines. Nevertheless any complementary information about the SPS impedance would be welcome. Broad-band impedance and parasitic effects on transverse and longitudinal motions will be reviewed. We shall mainly focus on the 270 GeV case with six equidistant bunches and 1011 particles per bunch. For other schemes results can be obtained in a similar fashion. Some relevant figures will be given for the situation at injection. (orig.)
Slot-coupled beam-signal-pickup development at Argonne National Laboratory
International Nuclear Information System (INIS)
The overall performance of slot couplers, at least for frequenciees below 2 GHz, can probably not match that of stripline based pickups. A measured, typical coupling at 2 GHz correesponds to about 6 to 7 ohms/slot-pair and produces about 80 phase shift/slot on the TEM line. Suppose a 12 to 14 slot array were constructed with these parameters. It would have a total 900 phase shift at about 1.7 GHz, and the coupling would be about 80 ohms at 2.0 GHz. Such an array would be 30 cm long. In a 10 m long straight section, one could place perhaps 25 such modules. After power adding, the net coupling would be about 80 x √25 = 400 ohms. This is 75% of the value which can be obtained by stripline structures (e.g. the FNAL Tevatron-I design). On the other hand, stripline structures may be difficult to construct for, let's say, a 4 to 8 GHz band. Slot coupled devices may then prove to be the more attractive choice. Slot couplers for these higher frequencies will be the subject of our R and D program at this time in the future
Energy Technology Data Exchange (ETDEWEB)
Niu, Hongsen
1995-02-10
The fundamental and practical aspects are described for extracting ions from atmospheric pressure plasma sources into an analytical mass spectrometer. Methodologies and basic concepts of inductively coupled plasma mass spectrometry (ICP-MS) are emphasized in the discussion, including ion source, sampling interface, supersonic expansion, slumming process, ion optics and beam focusing, and vacuum considerations. Some new developments and innovative designs are introduced. The plasma extraction process in ICP-MS was investigated by Langmuir measurements in the region between the skimmer and first ion lens. Electron temperature (T{sub e}) is in the range 2000--11000 K and changes with probe position inside an aerosol gas flow. Electron density (n{sub e}) is in the range 10{sup 8}--10{sup 10} {sup {minus}cm }at the skimmer tip and drops abruptly to 10{sup 6}--10{sup 8} cm{sup {minus}3} near the skimmer tip and drops abruptly to 10{sup 6}--10{sup 8} cm{sup {minus}3} downstream further behind the skimmer. Electron density in the beam leaving the skimmer also depends on water loading and on the presence and mass of matrix elements. Axially resolved distributions of electron number-density and electron temperature were obtained to characterize the ion beam at a variety of plasma operating conditions. The electron density dropped by a factor of 101 along the centerline between the sampler and skimmer cones in the first stage and continued to drop by factors of 10{sup 4}--10{sup 5} downstream of skimmer to the entrance of ion lens. The electron density in the beam expansion behind sampler cone exhibited a 1/z{sup 2} intensity fall-off (z is the axial position). An second beam expansion originated from the skimmer entrance, and the beam flow underwent with another 1/z{sup 2} fall-off behind the skimmer. Skimmer interactions play an important role in plasma extraction in the ICP-MS instrument.
Microwave transmission-line impedance data
Gunston, M A R
1996-01-01
A compendium of data for computing the characteristic impedance of transmission lines based on physical dimensions. Covers both conventional structures and unusual geometries, including coaxial, eccentric and elliptic coaxial, twin-wire, wire-above-ground, microstrip and derivatives, stripline, slabline and trough line. Also details numerous configurations of coupled lines.
Energy Technology Data Exchange (ETDEWEB)
Zotter, B. [European Organization for Nuclear Research, Geneva (Switzerland)
1996-08-01
This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)
Superconducting fault current-limiter with variable shunt impedance
Llambes, Juan Carlos H; Xiong, Xuming
2013-11-19
A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.
Scaling of induction-cell transverse impedance: effect on accelerator design
Energy Technology Data Exchange (ETDEWEB)
Ekdahl, Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-08-09
The strength of the dangerous beam breakup (BBU) instability in linear induction accelerators (LIAs) is characterized by the transverse coupling impedance Z_{⊥} . This note addresses the dimensional scaling of Z_{⊥} , which is important when comparing new LIA designs to existing accelerators with known i BBU growth. Moreover, it is shown that the scaling of Z_{⊥} with the accelerating gap size relates BBU growth directly to highvoltage engineering considerations. It is proposed to firmly establish this scaling though a series of AMOS calculations.
Dynamic behaviour of a beam coupled with a prestressed string - influence of damping
Czech Academy of Sciences Publication Activity Database
Fischer, Cyril; Frýba, Ladislav
Praha : Institute of Thermomechanics AS CR, v.v.i, 2007 - (Zolotarev, I.), s. 59-60 ISBN 978-80-87012-06-2. [ENGINEERING MECHANICS 2007. Žďár nad Sázavou (CZ), 14.05.2007-17.05.2007] R&D Projects: GA ČR(CZ) GA103/05/2066; GA AV ČR(CZ) IAA200710505 Institutional research plan: CEZ:AV0Z20710524 Keywords : dynamic load * beam * string Subject RIV: JM - Building Engineering
International Nuclear Information System (INIS)
The University of Maryland Dynamical Systems and Accelerator Theory Group carries out research in two broad areas: the computation of charged particle beam transport using Lie algebraic methods and advanced methods for the computation of electromagnetic fields and beam-cavity interactions. Important improvements in the state of the art are believed to be possible in both of these areas. In addition, applications of these methods are made to problems of current interest in accelerator physics including the theoretical performance of present and proposed high energy machines. The Lie algebraic method of computing and analyzing beam transport handles both linear and nonlinear beam elements. Tests show this method to be superior to the earlier matrix or numerical integration methods. It has wide application to many areas including accelerator physics, intense particle beams, ion microprobes, high resolution electron microscopy, and light optics. With regard to the area of electromagnetic fields and beam cavity interactions, work is carried out on the theory of beam breakup in single pulses. Work is also done on the analysis of the high frequency behavior of longitudinal and transverse coupling impedances, including the examination of methods which may be used to measure these impedances. Finally, work is performed on the electromagnetic analysis of coupled cavities and on the coupling of cavities to waveguides
Absolute calibration of a charge-coupled device camera with twin beams
International Nuclear Information System (INIS)
We report on the absolute calibration of a Charge-Coupled Device (CCD) camera by exploiting quantum correlation. This method exploits a certain number of spatial pairwise quantum correlated modes produced by spontaneous parametric-down-conversion. We develop a measurement model accounting for all the uncertainty contributions, and we reach the relative uncertainty of 0.3% in low photon flux regime. This represents a significant step forward for the characterization of (scientific) CCDs used in mesoscopic light regime.
Eslambolchi, Hossein
1984-01-01
It is well known that normal mode coupling in large diameter piezoelectric plates causes serious difficulties when attempting to operate over wide frequency bands. As a consequence transducers are commonly constructed as a mosaic of elemental resonators, each of which has a predominant single mode of mechanical oscillation at the frequency of interest. Such transducer arrays may be electrically steered to angles other than normal by applying different phases of driving voltages to different e...