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| TUPCH023 | Direct Observation of Beam-beam Induced Dynamical Beta Beating at HERA | electron, luminosity, proton, synchrotron | 1046 | ||
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The Hadron Electron Ring Anlage (HERA) at DESY provides collisions between a 920 GeV proton beam and a 27.5 GeV electron beam in two interaction regions. The strong beam-beam force, which mainly affects the electrons, induces a tune shift together with a dynamical beta beat. The latter leads to a modification of the transverse beam profile, which can be observed in different profile monitors in HERA. The time-like evolution of the electron beam shape during luminosity tuning and before and after dump of the proton beam, averaged over all bunches, could be studied by means of a synchrotron radiation profile monitor. Measurements with a wire scanner allowed to see the beam-beam force's influence on each individual bunch at the expense of resolution. The observations could be explained qualitatively in the frame of linear incoherent beam-beam interaction.
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| TUPCH033 | Automated Beam Optimisation and Diagnostics at MAMI | diagnostics, microtron, linac, synchrotron | 1076 | ||
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At the Institut fur Kernphysik (IKPH) of Mainz University the fourth stage of the Mainz Microtron (MAMI), a 855MeV to 1500MeV Harmonic Double Sided Microtron (HDSM), is now on the verge of first operation*. To provide an automated beam optimisation, low-Q-TM010 and TM110 resonators at each linac of the three cascaded RTMs and the two linacs of the new HDSM are used. These monitors deliver position, phase and intensity signals of each recirculation turn when modulating the beam intensity with 12ns-pulses (diagnostic pulses, max. rep. rate 10kHz). For operating the HDSM an extended system for displaying and digitising these signals was developed. High-bandwidth ADCs allow very comfortable to analyse, calibrate and automatically optimise the beam positions and phases during operation. The system is also used to adjust the transversal and longitudinal focussing according to the design parameters. Synchrotron radiation monitors, providing beam sizes and positions out of the bending magnets for each turn and on the entrance and exit of the linac axis, were a very helpful tool for beam-matching between the RTMs. Therefore a similar system was planned and constructed for the HDSM.
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*A. Jankowiak et al. “Status Report on the Harmonics Double Sided Microtron of MAMI C”, this conference. |
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| TUPCH062 | Synchrotron Radiation Diagnostics for the NSLS Booster | booster, synchrotron, diagnostics, radiation | 1154 | ||
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We developed an optical diagnostics system for the NSLS booster-synchrotron utilizing the synchrotron radiation from the dipole magnet. MATLAB based software allows to study the electron beam properties along the energy ramp. The trajectory, beam sizes and coupling at the different instants of time are retrieved from the analysis of the electron beam image. In the paper we present the system layout, as well as experimental results and upgrade plans.
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| TUPCH079 | Characterisation of the MAX-II Electron Beam: Beam Size Measurements | optics, synchrotron, electron, radiation | 1193 | ||
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Over the last year investigations of the MAX-II electron beam characteristics have been made. Examples of investigated parameters include the beam size, bunch length, vacuum and Touschek lifetimes, and the machine functions. Several upgrades of the MAX II ring have been performed since the commissioning 1995 like a new 100 MHz RF system with a 500 MHz Landau cavity, exchanged injector, and a variety of insertion devices. There is hence a need to systematically characterize the present machine. This systematic characterisation is now underway and this article describes details of the beam size measurements.
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| TUPCH090 | Electron Beam Profile Measurements with Visible and X-ray Synchrotron Radiation at the Swiss Light Source | synchrotron, emittance, SLS, radiation | 1223 | ||
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Two different methods of beam profile measurements using a) visible-to-UV range synchrotron radiation b) X-ray synchrotron radiation have been realized in a single diagnostics beam line at the Swiss Light Source. While the visible-to-UV part uses a focusing lens to create an image of the electron beam cross section, the X-ray part makes use of the pinhole camera principle. In the visible-to-UV case the vertically polarized synchrotron radiation renders an image heavily influenced by inherent emission and diffraction effects of synchrotron radiation. This turns out to be an advantageous influence in order to determine ultra small beam profiles. For each of the two methods practical point-spread function measurements, including all beam line components, and high-precision wave-optics based calculations (SRW code) of the synchrotron light characteristics were performed to ensure correct interpretation of the measured profiles. Results from both monitors will be presented to allow comparison.
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| TUPCH095 | Status of Synchrotron Radiation Monitor at TLS | synchrotron, radiation, controls, booster | 1232 | ||
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Synchrotron radiation monitor of the Taiwan Light Source have been upgraded recently. Improvement of optics and modelling was performed to improve accuracy of measurement for small beam size. Synchrotron light interferometer is implemented for complementary measurement. IEEE-1394 digital CCD camera is used to improve image transmission quality, camera remote control and to extend dynamic range. Intensify gated camera are included in this upgrade for dynamic property observation of the stored beam. Functionality enhancement of image analysis is also supported. Efforts and achievements will be summarized in this report.
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| TUPCH100 | Fiberoptics-based Instrumentation for Storage Ring Longitudinal Diagnostics | synchrotron, radiation, coupling, diagnostics | 1247 | ||
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Many beam diagnostic devices in today's synchrotron rings make use of the radiation emitted by the circulating particles. Such instruments are placed in close proximity of the accelerator, where in many instances they cannot be easily accessed for safety consideration, or at the end of a beamline, which because of its cost, can only move the light port a few meters away from the ring. We present a study on the coupling of synchrotron light into an optical fiber for all those application where the longitudinal properties of the beam are measured (i.e., bunch length, phase, intensity, etc.). By choosing an appropriate fiber it is possible to keep attenuation and dispersion at negligible values over a large bandwidth, so that this method would allow to have the diagnostic instruments directly in the control room, or wherever convenient, up to several hundred of meters away from the tunnel. This would make maintaining and replacing instruments, or switching between them, possible without any access to restricted areas. Additionally, the few components required to be near the ring (lenses and couplers) in order to couple the light into the fiber are intrinsically radiation-hard.
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| TUPLS137 | Design of the Utility System for the 3 GeV TPS Electron Storage Ring | storage-ring, controls, synchrotron, booster | 1828 | ||
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After 13-year operation of the Taiwan Light Source (TLS), National Synchrotron Radiation Research Center (NSRRC), had proposed to construct a new light sourc, Taiwan Photon Source (TPS) in the near future. TPS is preliminarily designed with 3.0 GeV in energy, 518.4m in circumference and 24 Double-Bend Achromat (DBA). This study designed the utility system, including the electrical power system, grounding system, de-ionized cooling water (DIW) system and air conditioning (AC) system for the TPS. Special considerations are focused on the stability of the electrical power and grounding system and temperature control of the DIW and AC systems. The power and cooling loads had been estimated according to each subsystem of the accelerator. Layouts of main utility equipment and piping system had also been preliminarily designed.
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| WEPLS022 | ILC Beam Energy Measurement based on Synchrotron Radiation from a Magnetic Spectrometer | photon, radiation, electron, synchrotron | 2442 | ||
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The magnetic spectrometer with a relative energy resolution of 5·10-5 was proposed for ILC beam energy measurements. The beam energy measurement is based on precise definition of the beam position at a resolution of 100 nm and B-field integral at an accuracy of 2E-5. A complementary method of the beam energy measurement is proposed at registration of synchrotron radiation (SR) from the energy spectrometer dipole magnets. The measurements of both edge horizontal positions for SR fan on a distance of 50-70 m downstream of the spectrometer magnets permit to determine the beam energy with required resolution. The main principles of the beam energy measurements based on SR, the numerical simulations of SR performed by the GEANT code and proposal of SR monitors with submicron resolution are discussed.
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| WEPLS135 | Piezoelectric Transformer Based Continuous-conduction-mode Voltage Source Charge-pump Power Factor Correction Electronic Ballast | APR, synchrotron, radiation | 2694 | ||
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This paper presents the piezoelectric transformer (PT) based continuous-conduction-mode (CCM) voltage source (VS) charge-pump (CP) power factor correction (PFC) electronic ballast. By replacing L-C resonant tank and transformer in the conventional CCM VS CP PFC electronic ballast with PT, the cost and volume can be reduced. The main drawback of conventional electronic ballast is that the input current has a narrow conduction angle, which causes rich harmonic that pollute the power system. However, the conventional CCM VS CP PFC electronic ballast is able to solve this problem but still require larger volume. Since the equivalent circuit of PT is identical to the conventional L-C resonant tank used in CCM VS CP PFC electronic ballast, the L-C resonant tank can be replaced by the PT to reduce the cost and volume. In addition, the inherent input capacitance of the PT works as a turn-off snubber for the power switches to decrease the turn-off voltage spikes and thus reduces the turn-off losses of the switches. The results show that the electronic ballast using PT achieved high power factor and the switches can be operated under ZVS condition.
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| THPCH024 | An Efficient Formalism for Simulating the Longitudinal Kick from Coherent Synchrotron Radiation | CSR, space-charge, synchrotron, simulation | 2829 | ||
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Coherent Synchrotron Radiation (CSR) can severely limit the performance of planned light sources and storage rings which push the envelope to ever higher bunch densities. In order to better simulate CSR, the formalism of Saldin is extended to work at lower energies and shorter length scales. The formalism is also generalized to cover the case of an arbitrary configuration of multiple bends.
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*E. L. Saldin et al. Nucl. Instrum. Methods Phys. Res., Sect. A 398, 373 (1997). |
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| THPCH039 | Beam Studies with Coherent Synchrotron Radiation from Short Bunches in the ANKA Storage Ring | synchrotron, radiation, storage-ring, FIR | 2868 | ||
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In the ANKA storage ring it is possible to store bunches with RMS lengths of the order of 1 ps using a dedicated optics with reduced momentum compaction factor. For short bunch operation a beam energy of 1.3 GeV is chosen as a trade-off between low energy longitudinal instabilities and the increase in natural bunch length with energy. At this medium energy (the energy range of the ANKA storage ring is 0.5 to 2.5 GeV) steady state emission of coherent synchrotron radiation is observed by the ANKA-IR beamline below the threshold current defined by the micro-bunching instability. At lower beam energies where the natural bunch length is significantly shorter, bursts of coherent synchrotron radiation are detected in spite of the longitudinal oscillation. The far infrared spectrum is sensitive to the dynamics of the charge distribution generating the radiation. Measurements of the frequency spectrum of the infrared detector signal add information on bunch dynamics. This paper gives an overview of the studies performed at the ANKA storage ring.
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| THPCH064 | Comparison of Three CSR Radiation Powers for Particle Bunches and Line Charges | CSR, radiation, synchrotron, simulation | 2931 | ||
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We are studying coherent synchrotron radiation (CSR) from arbitrary planar orbits as discussed in another abstract we submitted to EPAC06. It is important to have one-dimensional approximations. Here we report on work constructing and validating such approximations. As part of our work two well known papers by Saldin, Schneidmiller and Yurkov (SSY* are considered which deal with the CSR via a one-dimensional approximation whereby the electron bunch is modelled by a line density. Their one-dimensional approach is important because it is used in various CSR codes and since it serves to some extent as a role model for higher-dimensional models. The present report deals with some general aspects of the work of SSY. In particular, care is taken of the renormalization procedure and of the statistical description in terms of the line density. SSY use a renormalized retarded field whereas the present work uses the radiation field which is defined as half the difference of the retarded and advanced fields. The radiation field came into prominence when Dirac** introduced the Lorentz-Dirac equation.
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*E. L. Saldin, et al. Nucl. Instr. Meth. Phys. Res. A 398, 373 (1997) and 417, 158 (1998).**P.A.M. Dirac, Proc. Roy. Soc. (London) A167, 148 (1938). |
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| THPCH067 | Coherent Synchrotron Radiation Studies at the Accelerator Test Facility | injection, synchrotron, radiation, CSR | 2940 | ||
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Coherent Synchrotron Radiation (CSR) has been the object of recent experiments and is a topic of great importance for several accelerator currently in their design phase (LCLS, ILC, CIRCE). We present the results of several experimental sessions performed at the Advanced Test Facility - KEK (ATF). An infrared bolometer was used to detect the emitted infrared radiation in the 1-0.05 mm wavelength range as a function of several beam parameters (beam current, RF power, extraction timing, photoinjector laser phase). The beam energy spread was also recorded. We found that the mismatch between injected and equilibrium beam is the source of the coherent signal detected concurrently with the bunch injection.
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| THPCH186 | Magnetic Field Measurement and Fine-tuning of Kickers | kicker, injection, storage-ring, synchrotron | 3236 | ||
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We have demonstrated an algorithm which promisingly can tune the pulse shape of current and magnetic field of kicker systems in-situ. This algorithm includes gap shimming of the ferrite magnets to adjust the pulse width of the excitation current and changing the resistance of the secondary coils to modify the pulse curvatures of each kicker. With the empirical formula derived from the systematic measurement on the magnetic field and the pulse current in laboratory, we can reduce the pulse-shape difference among the kicker magnets in the injection section of the storage ring, with no need to do anything on the pulsers and high voltage power suppliers. This approach can efficiently increase the injection efficiency which is demanding in the top-up injection mode adopted by many new facilities of synchrotron radiation.
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| THPLS001 | The Strict Solution of a Radiation Problem in Toroidal Cavity | radiation, synchrotron, plasma, electromagnetic-fields | 3260 | ||
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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.
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| THPLS042 | Observation of THz Synchrotron Radiation Burst in UVSOR-II Electron Storage Ring | radiation, synchrotron, electron, CSR | 3380 | ||
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Very intense THz synchrotron radiation bursts have been observed in single-bunch operation in the UVSOR-II electron storage ring*. The observation was performed in an infrared beam line in UVSOR-II by using a liquid-He-cooled In-Sb hot-electron bolometer that has a good response time of several microseconds. Thanks both to the beam line and the detector, it is clearly observed that the intense bursts have typical macroscopic and microscopic temporal structure. Macroscopically, it is clearly observed that the bursts tend to be generated with quasi-periodic structure in which the period tends to depend on the beam intensity. From a microscopic point of view, each burst has also quasi-periodic structure in itself, and the period almost corresponds to the half value of the inverse of the synchrotron oscillation frequency. The peak intensity of the bursts was about 10000 times larger than that of ordinary synchrotron radiation in the same wavelength region. The extremely high intensity strongly suggests that the bursts are coherent synchrotron radiation, although the radiation wavelength was much shorter than the electron bunch length.
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*Y. Takashima et al., Jpn. J. Appl. Phys. 44, No.35 (2005) L1131. |
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| THPLS056 | Synchrotron Radiation Monitors at ALBA | synchrotron, radiation, booster, vacuum | 3410 | ||
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ALBA is a 3 GeV, low emittance third generation synchrotron light source that is in the construction phase in Cerdanyola, Spain. Synchrotron Radiation Monitors (SRM) are one of the most useful, non-destructive tools to easily obtain information of three important parameters for a synchrotron user: beam position, beam dimensions and beam stability. These monitors diagnose beam performance using the radiation produced when the beam traverses a bending magnet. An extensive usage of SRM, based on the visible part of the spectrum, is planned in the ALBA synchrotron: Linac, Booster, Transfer Lines and the Storage Ring. The latter will be equipped as well with an SRM based on the x-ray part of the spectrum, using the PinHole technique in order to accurately measure the low beam size and emittance. This paper describes the different SRM designs for the ALBA light source.
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| THPLS065 | Optimization for Taiwan Photon Source Electron Beam Position Monitors through Numerical Simulation | simulation, electron, photon, synchrotron | 3436 | ||
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One of the key steps toward successfully building the newly proposed 3rd generation synchrotron radiation research facility, Taiwan Photon Source (TPS), is to optimize the design of the high resolution electron beam position monitors through numerical simulation. With more advanced electromagnetic simulation tool like MAFIA tailored specifically for particle accelerator, the design for the high resolution electron beam position monitors can be tested in such environment before actually fabricated and physically tested. The design goal of our high resolution electron beam position monitors is to achieve 0.1 micron resolution if allowed by engineering limitations. The design consideration to achieve this 0.1 micron resolution goal will also be discussed. The first design has been carried out and the correlated simulations were also carried out with MAFIA. The results are presented and discussed here. Sensitivity as high as 200 has been achieved at 500 MHz. Further study will also be described.
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| THPLS122 | Investigations of the Thermal Beam Load of a Superconducting In-vacuum Undulator | undulator, vacuum, radiation, synchrotron | 3568 | ||
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Both the resistive wall effect and the synchrotron radiation~\cite{wallen, casalbuoni, chou} can warm up the cold bore of a superconductive in-vacuum undulator. For the in ANKA installed superconducting undulator measurements showed that the dominant heat load contribution comes from the synchrotron radiation generated in the upstream bending magnet: 1 W per 100 mA stored current at a beam energy of 2.5 GeV and an undulator gap of 8 mm.
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| THPLS123 | A Year's Experience with a Superconducting Undulator in the Storage Ring ANKA | undulator, emittance, optics, synchrotron | 3571 | ||
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In ANKA the worldwide first superconducting undulator demonstrator designed for a storage ring was operated during the last year. The undulator has 100 periods and a period length of 14 mm. During the first year the heat transfer from the beam to the cold bore was investigated and the spectra and the electrical tunability together with a monochromator was measured. The results are so encouraging that plans exist to equip ANKA with two more undulators, one with the opportunity to double electrically the period length and one with electrically variable polarization direction.
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