synchrotron

Paper	Title	Other Keywords	Page
MOBAU01	Self-Force-Derived Mass of an Electron Bunch	electron, acceleration, electromagnetic-fields, synchrotron-radiation	1
	E. Saldin DESY, Hamburg
	The properties of Lorentz transformations for energy and momentum in electromagnetic systems are illustrated in a simple example involving a short electron bunch moving in a bending magnet. The famous 4/3 problem in electromagnetic mass is discussed.
	Slides
MOPPH026	Three-Dimensional Theory of the Smith-Purcell Free-Electron Laser	electron, laser, free-electron-laser, radiation	77
	H. L. Andrews, C. A. Brau, J. D. Jarvis Vanderbilt University, Nashville, Tennessee
	We present an analytic theory for the operation of a Smith-Purcell free-electron laser (SPFEL) that includes transverse diffraction of the optical beam. For the case of an infinitely wide electron beam, this theory agrees with previous two-dimensional analyses. When the electron beam is narrow compared to the mode, the gain (amplifier regime) is substantially reduced by diffraction, while its dependence on the beam current is increased due to gain guiding. A 5/2-power dispersion relation replaces the conventional cubic dispersion relation. Additionally, the constituent waves of the laser mode are found to have different transverse decay rates. An estimate of the start current (oscillator regime) of the device is obtained by satisfying the appropriate boundary conditions on the beam axis.
MOPPH032	Development of Metal Mesh Based Quasi-optical Selective Components and Their Application in High-power Experiments at Novosibirsk Terahertz FEL	radiation, laser, controls, synchrotron-radiation	89
	B. G. Goldenberg, P. V. Kalinin, V. V. Kubarev, N. Vinokurov, S. A. Kuznetsov BINP SB RAS, Novosibirsk
	Successful realization of terahertz research programs at the Novosibirsk FEL-facility requires detailed development, designing and optimization of passive quasi-optical selective components, intended for polarization and frequency gating of powerful THz-beams of NovoFEL radiation. Along with desired selective characteristics such components should be capable of operating over a long period of time under high-power load conditions (a few hundred Watts of average incident radiation power) without noticeable degradation of their properties. It admits to employ in selective components only low absorbing and thermostable materials, such as high conductivity metals and special types of polymers. This report is devoted to development of metal mesh based selective structures, such as polarizing beamsplitters (attenuators) and different frequency filters, and their application in high-power THz-experiments. Possibilities and prospects of two main production technologies are discussed: 1) conventional photolithography destined for manufacturing thin metal structures deposited on low-absorbing thermostable polymer films; 2) LIGA-technique intended for producing thick substrate-free metal structures.
TUPPH008	Beam Dynamics Studies on the UVSOR-II Free Electron Laser	laser, electron, injection, simulation	236
	M.-E. Couprie SOLEIL, Gif-sur-Yvette M. Hosaka Nagoya University, Nagoya M. Katoh, A. Mochihashi, M. Shimada UVSOR, Okazaki G. Lambert RIKEN Spring-8, Hyogo M. Labat CEA, Gif-sur-Yvette
	In the Coherent Harmonic Generation Free Electron Laser configuration, an external laser source is seeded inside a first undulator. The interaction between the electron beam and this seed induces energy modulation of the bunch, further converted into a density modulation, producing coherent radiation in a second undulator. The energy modulation enhances the energy spread of the electron bunch, converted by the machine optics into a modification of its longitudinal distribution. In the case of a storage ring FEL, the electrons are re-circulating: the same bunch keeps interacting with the seeded laser, and relaxation of the distribution is only allowed in between two laser injections. Such specific dynamics has been studied on the CHG FEL of UVSOR-II storage ring (Japan). The electron beam stored at 600 MeV is seeded using a 2.5 mJ, 1 kHz, 1.2 ps Ti:Sa laser at 800 nm wavelength, allowing radiation at 266 nm (third harmonic). A Streak Camera is used to record the evolution of the longitudinal profiles as a function of the repetition rate and average power of the seeding laser, leading to bunch lengthening and distortion dynamical analysis. It appeared that because the heating induced by the interaction remains local, the refreshment process of the electronic distribution is modified. The experimental results are compared to simulations using SYNC.
WEPPH004	Numerical Calculations of the Radiation Emitted from the FLASH Infrared Undulator	undulator, radiation, photon, synchrotron-radiation	322
	V. Kocharyan, J. Rossbach, O. Grimm DESY, Hamburg
	The results from the magnetic measurements with the FLASH infrared electromagnetic undulator reported in a companion paper where used as input for calculations of the expected radiation spectrum. Especially the behaviour of the device at small first harmonic wavelengths, i.e. small excitation currents, is important for beam diagnostics, as here the high intensity in a narrow band is a distinct advantage over broad-band sources to detect small bunch structures. The field quality is reduced at small currents due to imperfections in the yoke construction and limited compensation by correction windings. A determination of the lower limit for useful operation of the device follows from these calculations.