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electromagnetic-fields

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MOPCH072 Adjustable Input Coupler Development for Superconducting Accelerating Cavity simulation, cryogenics, ERL, linac 193
 
  • M.V. Lalayan, M.A. Gusarova, V.I. Kaminsky, A.A. Krasnov, V.A. Makarov, N.P. Sobenin
    MEPhI, Moscow
  • A.A. Zavadtsev, D.A. Zavadtsev
    Introscan, Moscow
  The waveguide and coaxial-type input couplers for Energy Recovery Linac type injector cavity electrodynamical and thermal simulation results are presented. The devices are designed to feed the superconducting cavity with up to 500 kW RF power in continuous wave regime at 1.3 GHz operating frequency. The cavity external quality factor adjustment is provided. The heat load to the cryogenic system was lowered to a tolerable level by coupler design optimization.  
 
MOPLS076 The Stimulated Breit-Wheeler Process as a Source of Background e+e- Pairs at the ILC photon, electron, background, resonance 727
 
  • A.F. Hartin, A.F. Hartin
    OXFORDphysics, Oxford, Oxon
  Passage of beamstrahlung photons through the bunch fields at the interaction point of the ILC determines background pair production. The number of background pairs per bunch crossing due to the Breit-Wheeler, Bethe-Heitler and Landau-Lifshitz processes is well known. However the Breit-Wheeler process also takes place in and is modified by the bunch fields. A full QED calculation of this Stimulated Breit-Wheeler process reveals cross section resonances due to the virtual particle reaching the mass shell. The one loop Electron Self energy in the bunch field is also calculated and included as a radiative correction. The bunch field is considered to be a contant crossed electromagnetic field with associated bunch field photons. Resonance is found to occur whenever the energy of contributed bunch field photons is equal to the beamstrahlung photon energy. The Stimulated Breit-Wheeler cross section exceeds the ordinary Breit-Wheeler cross section by several orders of magnitude and a significantly different pair background may result.  
 
TUPCH101 Modeling of Ultrafast Streak Cameras electron, simulation, cathode, acceleration 1250
 
  • G. Huang, J.M. Byrd, J. Feng, H.A. Padmore, J. Qiang, W. Wan
    LBNL, Berkeley, California
  We present progress on modeling of streak camera with application to measurement of ultrafast phenomena. Our approach is based on treating the streak camera as a photocathode gun and applying modeling tools for beam optics, space charge, and electromagnetic fields. We use these models to compare with experimental results from a streak camera developed at the Advanced Light Source. Furthermore, we explore several ideas for achieving sub-100 fsec resolution.  
 
TUPCH127 Fine Grooving of Conductor Surfaces of RF Input Coupler to Suppress Multipactoring simulation, KEKB, KEK, coupling 1310
 
  • T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi
    KEK, Ibaraki
  An RF input coupler to feed high power into an accelerating cavity with heavy beam loading undergoes many multipactoring zones due to the wide range of the input RF power. Furthermore, a regular coaxial line is more subject to multipactoring than a rectangular waveguide because of the uniformity of the electromagnetic field. Grooving the conductor surfaces of the coaxial line is a promising method to suppress multipactoring under any conditions expected in the above cases. This paper reports results of our multipactoring simulation study and the high power test of the input coupler with a grooved coaxial line.  
 
TUPCH142 Development of a Novel RF Waveguide Vacuum Valve vacuum, CTF3, CLIC, coupling 1349
 
  • A. Grudiev
    CERN, Geneva
  The development of a novel rf waveguide vacuum valve is presented. The rf design is based on the use of TE0n modes of circular waveguides. In the device, the T·1001 mode at the input is converted into a mixture of several TE0n modes which provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the T·1001 mode at the output. There are a number of advantages associated with the absence of surface fields in the region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·1001 mode and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3 (CTF3) are presented showing in particular that the rf power transmission losses are below 1%.  
 
WEPCH073 Asymptotic Analysis of Ultra-relativistic Charge radiation, vacuum, electron, controls 2086
 
  • D.A. Burton, J. Gratus, R. Tucker
    Lancaster University, Lancaster
  A new approach is developed for analysing the dynamic behaviour of distributions of charged particles in an electromagnetic field. Noting the limitations inherent in the Lorentz-Dirac equation for a single point particle, a simple model is proposed for a charged continuum interacting self-consistently with the Maxwell field in vacuo. The model is developed using intrinsic tensor field theory and exploits to the full the symmetry and light-cone structure of Minkowski spacetime. This permits the construction of a regular stress-energy tensor whose vanishing divergence determines a system of non-linear partial differential equations for the velocity and self-fields of accelerated charge. Within this covariant framework a particular perturbation scheme is motivated by an exact class of solutions to this system describing the evolution of a charged fluid under the combined effects of both self and external electromagnetic fields. The scheme yields an asymptotic approximation in terms of inhomogeneous linear equations for the self-consistent Maxwell field, charge current and time-like velocity field of the charged fluid and is defined as an ultra-relativistic configuration.  
 
WEPCH131 Development of Numerical Code for Self-consistent Wake Field Analysis with Curved Trajectory Electron Bunches simulation, electron, radiation, coupling 2230
 
  • H. Kawaguchi
    Muroran Institute of Technology, Department of Electrical and Electronic Engineering, Muroran
  • K. Fujita
    Hokkaido University, Sapporo
  Strongly interacting phenomena of electromagnetic radiation fields and ultra-relativistic electron is one of great interests in accelerator science such as in electron beam dynamics at the bunch compressor. The phenomena are described by time domain boundary value problem for the Lienard-Wiechert solutions. Authors develop a time domain boundary element method for self-consistent wake fields analysis of electromagnetic fields and charged particles. To use boundary integral equation for describing the electromagnetic fields, the time domain boundary value problems for the Lienard-Wiechert solution can be naturally formulated and we can simulate the wake fields phenomena with electron beam dynamics. In this paper, beam dynamics of curved trajectory electron bunches inside uniform beam tube are numerically simulated by using 2.5 dimension time domain boundary element technique. Various effects of closed beam tube for ultra-relativistic electron dynamics are considered comparing with the Lienard-Wiechert solutions in free space.  
 
THPCH016 Transfer Matrix of Linear Focusing System in the Presence of Self-field of Intense Charged Particle Beam focusing, quadrupole, dipole, ion 2817
 
  • Yu. Kazarinov
    JINR, Dubna, Moscow Region
  Within the framework of moments method, the computation algorithm of the transfer matrix in the presence of self-field of the intense charged particle beam is given. The transfer matrix depends on both the linear external electromagnetic field parameters and the initial value of the second order moments of the beam distribution function. In the case of coupled degrees of freedom, the independent 2D subspaces of the whole phase space are found by means of the linear transformation of the phase space variables. The matrix of this transformation connects with second order moments of the beam distribution function. The momentum spread of the beam is taken into account also.  
 
THPLS001 The Strict Solution of a Radiation Problem in Toroidal Cavity radiation, synchrotron, synchrotron-radiation, plasma 3260
 
  • T.H. Harutunyan
    YSU, Yerevan
  • E.D. Gazazyan, M.K. Khojoyan
    YerPhI, Yerevan
  The radiation of charged particles bunch which is moving along the axes of toroidal cavity cross section is considered. The toroidal cavity has a finite value of the quality factor and is filled with special symmetry inhomogeneous dielectric medium. The problem's solution is based on the complete set of the toroidal cavity's own modes being defined strictly for the mentioned dielectric medium the cavity is filled with. The charged particles bunch exists in the cavity during a finite time period and the charged bunch's arising and vanishing effects are examined and are taken into account as well. The toroidal cavity is considered as a convenient model to investigate the electromagnetic properties of the tokamak system, using the defined modes.  
 
THPLS023 Wake Computations for the Beam Positioning Monitors of PETRA III PETRA, simulation, vacuum, insertion 3326
 
  • A.K. Bandyopadhyay, A. Joestingmeier, A.S. Omar
    Otto-Von-Guericke University, Magdeburg
  • K. Balewski, R. Wanzenberg
    DESY, Hamburg
  At DESY it is planned to convert the PETRA ring into a synchrotron radiation facility, called PETRA III, in 2007. For proper design of PETRA III it is very important to estimate the wakes due to various discontinuities along the beam pipe. This article is on the wake computations for the beam positioning monitors (BPMs) in the PETRA III beam pipe. Two computer codes, namely MAFIA and Microwave Studio, were used for the electromagnetic field computations. Convergence tests and the agreement between the results of both softwares were taken as criteria in order to validate the results.