International Journal of Applied Electromagnetics and Mechanics - Volume 14, issue 1-4

Authors: Marquardt, Niels

Article Type: Research Article

Abstract: Electron storage rings have become very powerful sources of electromagnetic radiation covering a wide spectral range. In particular, the high-flux, long-wavelength infrared (IR) radiation from synchrotron light sources is increasingly used for spectroscopy in basic and applied research. Besides ordinary IR synchrotron radiation emitted from homogeneous magnetic dipole fields (i.e. dipole radiation DR), another high-brilliant source of IR radiation has been discovered recently, which is emitted by relativistic electrons traversing the inhomogeneous …edge fields of bending magnets (i.e. edge radiation ER). In this paper a comparison is made between the very different radiation characteristics of DR and ER. Plans for the construction of a high-brilliant IR beamline at the storage ring DELTA, dedicated to an investigation of ER and to its use as a sensitive tool for electron-beam diagnostics, are presented. Moreover, various experiments for ellipsometry, FT-IR micro-spectroscopy and photothermal IR radiometry, exploiting the well-focussed, broadband IR-photon flux of high intensities are discussed. Show more

DOI: 10.3233/JAE-2002-371

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 185-190, 2002

Authors: Watanabe, T. | Sugahara, J. | Yoshii, K. | Ueda, T. | Uesaka, M. | Yoshimatsu, T. | Kondo, Y. | Sugiyama, Y. | Sasaki, S. | Ishi, K. | Shibata, Y.

Article Type: Research Article

Abstract: Measurements of longitudinal bunch length of picosecond electron bunches have been performed by the femtosecond streak camera, the interferometer and the polychromator and their results were compared with one another. As regards the radiation, transition radiation and diffraction radiation were investigated through the diagnostics. As a result, the fine agreements between them within 200 fs were obtained and the reliability of the interferometer and the polychromator for the diagnostics of less than …picosecond electron bunch were verified. Furthermore, nondestructive diagnostics for subpicosecond bunches was performed utilizing coherent diffraction radiation (CDR) interferometry. Show more

DOI: 10.3233/JAE-2002-386

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 191-196, 2002

Authors: Bane, K.L.F. | Naito, T. | Okugi, T. | Qin, Q. | Urakawa, J.

Article Type: Research Article

Abstract: We present energy spread and bunch length measurements at the Accelerator Test Facility (ATF) at KEK, as functions of current, for different ring rf voltages, and with the beam both on and off the coupling resonance. We fit the on-coupling bunch shapes to those of an impedance model consisting of a resistor and an inductor connected in series. We find that the fits are reasonably good, but that the resulting impedance is unexpectedly large.

DOI: 10.3233/JAE-2002-389

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 197-202, 2002

Authors: Nakamura, Kei | Watanabe, Takahiro | Ueda, Toru | Yoshii, Koji | Uesaka, Mitsuru

Article Type: Research Article

Abstract: Numerical analysis and measurement of longitudinal bunch length of subpico- and picosecond electron beams by the fluctuation method has been carried out at the S-band twin linear accelerators at Nuclear Engineering Research Laboratory (NERL), University of Tokyo. The diagnostics method utilizes a statistical analysis of shot-noise-driven fluctuations in incoherent radiation. Measurements were performed on Cherenkov radiation emitted by ∼ 1.0 ps (FWHM), 20 MeV electron bunch. As a result, the fluctuation method …indicated 5 times longer than that by the streak camera. The discrepancy was caused by neglecting the influence of the transverse emittance. Then, the influence of the transverse profile upon the measurement was analyzed and discussed. Show more

DOI: 10.3233/JAE-2002-387

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 203-208, 2002

Authors: Drabik, A. | Drabik, W. | Rabinski, M.

Article Type: Research Article

Abstract: The thermal loading of thin metal foils used as extraction windows in high current electron accelerators is one of the most important processes which should be analysed during the design of such devices. Heat loads at metal surface are also of special interest in many other plasma applications. The distribution of heat loads at the surface of thin metal foil is evaluated from the energy absorption in the foil and forced cooling with air flow. Time dependence of temperature …distribution at the foil surface is calculated from the two-dimensional heat conduction equation. The simplified heat transient analysis is also given to determine the influence of scanning frequencies, electron beam size and shape ,shape of current impulses in scanning coils, energy loss in foil, the beam current and air cooling coefficient on time evolution of temperature for an arbitrary fixed point at the foil in first period of electron beam scanning. Show more

DOI: 10.3233/JAE-2002-372

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 209-213, 2002

Authors: Tomioka, Satoshi | Nisiyama, Shusuke | Enoto, Takeaki

Article Type: Research Article

Abstract: For the purpose of non-destructive measurement of the cross-sectional shape of an electron beam, we have studied a detection system that is composed of both a number of antennas and a current monitor. The antenna detects an electric field, and the current monitor detects an integral of beam currents. The signals acquired from these detectors are applied as the input of an inverse problem. We adopt the genetic algorithm to simulate the profile measurement as …an inverse problem analysis. The results showed that this detection system is partially effective, even though this system is an "ill-posed problem" (i.e. the number of input data parameters is less than the number of parameters to be estimated). We also found that the current monitor, which cannot acquire position-dependent information, is nevertheless useful to accelerate the convergence of sub-optimal beam profiles. Show more

DOI: 10.3233/JAE-2002-369

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 215-219, 2002

Authors: Fukasawa, Atsushi | Kobayashi, Tetsuya | Uesaka, Mitsuru | Urakawa, Junji | Higo, Toshiyasu | Akemoto, Mitsuo | Hayano, Hitoshi

Article Type: Research Article

Abstract: Compact inverse Compton scattering hard X-ray source based on the X-band linac is numerically designed. The theoretical scaling law for emittance vs. charge / RF frequency was confirmed by the numerical analysis. The 3.5 cell RF gun with the field strength at the cathode surface 140 MV/m can produce the 2.1 MeV, 240 pC electron bunch, although the energy spread, 8% only 10^{5} photons/shot in this system, we have proposed several schemes to …achieve 10^{11} photons/10ms based on state-of-the-art technologies. Show more

DOI: 10.3233/JAE-2002-496

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 221-226, 2002

Authors: Dobashi, K. | Fukuda, M. | Hirose, T. | Kamiya, Y. | Sakai, I. | Aoki, T. | Higurashi, A. | Oshima, T. | Washio, M. | Kurihara, Y. | Okugi, T. | Omori, T. | Urakawa, J.

Article Type: Research Article

Abstract: We performed an experiment of high brightness gamma(γ)-rays production through laser-electron(e^{-} ) collisions using an insertion device with a short focal length of laser optics. Number of generated γ-rays with the bunch length of 26 psec (r.m.s) was 0.92 × 10^5 /bunch, thus leading to brightness 2.5 × 10^{17} /(mm^2 · mrad^2 · 0.1% band-width · sec). Quantitative considerations on the basis of …numerical model permitted to elucidate how characteristics of ^{-} and laser beam influence collision mechanisms. Show more

DOI: 10.3233/JAE-2002-497

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 227-231, 2002

Authors: Kinoshita, Kenichi | Ohkubo, Takeru | Yoshii, Koji | Harano, Hideki | Uesaka, Mitsuru

Article Type: Research Article

Abstract: For ultrafast material analyses, we constructed the time-resolved X-ray diffraction system utilizing ultrashort X-rays from laser produced plasma generated by the 12TW-50fs laser at Nuclear Engineering Research Laboratory. Ultrafast transient changes in laser-irradiated GaAs crystals were observed as X-ray diffraction patterns. A subpeak appears in X-ray diffraction profiles and shifts its position gradually as time goes in the case of 1.3 mJ/mm^2 laser fluence. Experimental results were compared with numerical …analyses to infer the atomic arrangement during the transition. Show more

DOI: 10.3233/JAE-2002-385

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 233-236, 2002

Authors: van Rienen, Ursula | Glock, Hans-Walter | Hecht, Dirk | Rothemund, Karsten

Article Type: Research Article

Abstract: This paper presents results on the computation of Higher Order Modes (shortly HOMs) in the designs for the accelerating structures which have already been built in into the TESLA [1] Test Facility (TTF) or are presently being studied as final design for the TESLA collider. Depending on the complexity of the studied arrangement different computational strategies are followed: 1. the use of commercial software packages like MAFIA [2] or CST Microwave Studio (MWS) [2] on workstations, …and 2. a recently implemented tool for Coupled S-Parameter Calculation (CSC) which easily allows to calculate the scattering properties of rf-sections connected to each other with arbitrary topology or to determine eigenmodes of resonating structures. Show more

DOI: 10.3233/JAE-2002-374

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 14, no. 1-4, pp. 237-242, 2002