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| MOP24 | Using a Solid State Switch for a 60kV Bouncer to Control Energy Spread during the Beam Pulse* | linac, coupling, impedance, power-supply | 87 | ||||
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The beam injected into the IPNS Linac is from a column utilizing a Cockcroft-Walton voltage source. The accelerating column consists of a single high gradient gap. To lessen the likelihood of gap voltage breakdown, we pulse (“bounce”) the column voltage up during the beam pulse allowing the column DC voltage to be lower. The accelerating voltage is supplied through a 5 MΩ resistor and has only small capacitance to hold the voltage constant during the beam pulse. A capacitor is connected between the high voltage end of the column and the bouncer pulse generator. The bouncer pulse increases the column voltage to the proper level just microseconds before the beam pulse. A slope on the top of the bouncer pulse allows for correction to be added, compensating for the voltage droop that results from beam loading. The bouncer that has served this purpose in the past utilized a tube amplifier. In searching for a suitable replacement system it was decided that the system should be able to deliver a 60 kV pulse and the slope on the top of the pulse could be controlled by an RC rise. A solid state switch was purchased for this application. Switch protection and other design decisions will be discussed.
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| MOP63 | Numerical Calculation of Coupling Impedances in Kicker Modules for Non-Relativistic Particle Beams | simulation, coupling, impedance, kicker | 162 | ||||
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In the context of heavy-ion synchrotrons, coupling impedances in ferrite-loaded structures (e.g. fast kicker modules) are known to have a significant influence on beam stability. While bench measurements are feasible today, it is desirable to have the coupling impedances in hands already during the design process of the respective components. To achieve this goal, as a first step, we have carried out numerical analyses of simple ferrite-containing test systems within the framework of the Finite Integration Technique[1]. This amounts to solving the full set of Maxwell's equations in frequency domain, the particle beam being represented by an appropriate excitation current. With the resulting electromagnetic fields, one may then readily compute the corresponding coupling impedances. Despite the complicated material properties of ferrites, our results show that their numerical treatment is possible, thus opening up a way to determine a crucial parameter of kicker devices before construction.
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[1] Weiland, T., Electronics and Communication (AEÜ), Vol. 31 (1977), p. 116. |
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| TUP61 | Beam Analysis Using the IPNS Linac ESEM | linac, diagnostics, quadrupole, target | 405 | ||||
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The Energy Spread and Energy Monitor (ESEM) is an on-line, non-intrusive diagnostic used to characterize the output beam from the 200 MHz, 50 MeV linac. The energy spread is determined from a 3-size, longitudinal emittance measurement and energy is derived from TOF analysis. Presently, a single particle distribution is used to yield energy and energy-spread results. Effort is on-going to allow for more realistic distributions to be included. Signals are detected on terminated 50 Ω, stripline BPMs. Each BPM is constructed with four striplines: top, bottom, left and right. Until recently, the ESEM signals were taken solely from bottom striplines in four separate BPM locations in the transport line between the linac and synchrotron. We have begun to use the top stripline data to examine, in more detail, beam position and attempt to measure beam size. The electrostatic coupling between the stripline and the beam depends on the capacitance, which in turn is inversely related to the beam-stripline separation. The electrostatic portion of fluctuations in beam motion will be nonlinear, possibly allowing one to infer beam size.
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| TUP69 | Precision Alignments of Stripline BPMs with Quadrupole Magnets for TTF2 | quadrupole, alignment, linac, pick-up | 426 | ||||
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We report on our alignment setup to calibrate beam position monitors (BPM) with respect to the magnetic axis of the quadrupole magnets used in the warm sections of the TESLA Test Facility (TTF2). The Stripline BPM's are fixed inside the quadrupole magnets. A streched wire measurement was used to calibrate the electrical axis of the BPM wrt. to the magnetic axis of the quadrupole.
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| TUP73 | Beam Instrumentation Using BPM System of the SPring-8 Linac | feedback, linac, storage-ring, booster | 438 | ||||
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A beam position monitor (BPM) system of the SPring-8 linac has been operated since 2002. The following upgrade programs have been carried out during this period: The BPMs were installed in the linac's dispersive sections. A synchronized accumulation of beam position data into the database system started. A feedback control of steering magnets for beam position stabilization has been under development. In this conference the authors report a performance of the BPM system, and discuss its usefulness for beam diagnostics, machine diagnostics and beam stabilization.
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| TUP75 | The High Accuracy RF Phase Detector Research for 200 MeV LINAC | linac, radiation, electron, synchrotron-radiation | 444 | ||||
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The basic configuration of one experimental RF Phase detector and its research significance is introduced by characteristic of Hefei 200 MeV RF Linear accelerator and developments of RF Phase detector technology. The beam energy could be stabilized by implementing RF Phase detector into phase locked system for 5 cascaded accelerator tubes, which composed 200 MeV linac as the injector of Hefei Light Source (HLS). The tabletop experiments are given and the RF Phase detector is tuned in the off-line status. The microwave in 2856 MHz under CW mode is differentiated accurately by the developed RF phase detector. The measured results are better than prediction. The accuracy of the basic configuration of the RF Phase detector is verified, which establishes foundations for further in-line experiments.
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| WE104 | State of the Art Electron Bunch Compression | electron, radiation, emittance, bunching | 528 | ||||
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Many accelerator applications such as advanced accelerator R&D, free-electron laser drivers and linear colliders, require high peak current electron bunches. The bunch is generally shortened via magnetic compression. In the present paper we review various bunch compression schemes and discuss their limitations. We present experimental results, achieved at various facilities, along with on-going theoretical work on promising novel compression techniques.
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Transparencies
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| WE203 | Challenges of Linac Driven Light Sources | linac, radiation, brilliance, synchrotron-radiation | 543 | ||||
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The use of linacs allows novel light sources to be conceived by not being limited by equilibrium dynamics or IBS effects. These new sources can be single pass or recirculated (with or without energy recovery) or linac augmented storage rings. They allow tuneable polarised radiation of unprecedented brilliance, short pulse lengths that may reach the atto-second scale and full coherence. Both SC and NC machines are being proposed, designed and constructed. Photon output characteristics range from incoherent synchrotron radiation to SASE to seeded HGHG. The proposed beams can be low to high average current and pulse time structures range from CW to highly variable with mutual exclusion amongst different forms of operation. The multiple challenges of these machines reside not only in the requirement of beams of extremely high quality (energy, emittance, energy-spread and temporal stability) for the brightest, shortest wavelength sources but also in the demanding technologies and control of beam-machine interactions for the high current energy recovery ones. The paper gives an overview of these broad challenges and of the directions taken to reach the objectives of a user facility.
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Transparencies
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| THP89 | Measured RF Properties of the DTL for the J-PARC | insertion, linac, target, quadrupole | 809 | ||||
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RF properties of the second DTL tank for J-PARC have been measured in KEK. The required flatness and stability of the accelerating field of the tank have been achieved by the tunung of the post-couplers, whose shape were modified to adjust the resonant frequency ?324 MHz). Because the third DTL tank has assembled, the rf measurement and the post-coupler tuning will be started soon. Thus the measured results for both tanks will be described in the paper.
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| THP95 | Electro Polishing of Niobium Cavities at DESY | acceleration, cathode, electron | 824 | ||||
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At DESY a facility for electro polishing (EP) of the super conducting (s.c.) TESLA/TTF cavities have been built and is operational since summer 2003. The EP infrastructure is capable to handle single-cell structures and the standard TESLA/ TTF nine-cell cavities. Several electro polishing processes have been made since and acceleration voltage up to 40 MV/m have been reached in nine cell structures. We report on measurements and experiences gained since 2003 as well as on handling procedures developed for the preparation of electro polished resonators. Specific data like heat production, variation of current density and bath aging will be presented. Another important point for reproducible results is the quality control of the electro polishing process. First quality control steps to be implanted in the EP procedure for large-scale production will be described.
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| FR204 | The Physics Perspectives at the Future Accelerator Facility FAIR | antiproton, ion, target, hadron | 858 | ||||
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The physics perspective of the approved future international accelerator Facility for Anti-proton and Ion Research (FAIR) near Darmstadt, Germany will be outlined. The physics programme will comprise many body aspects of matter ranging from macroscopic system like highly correlated plasmas down to the properties of baryons and nuclear matter at high baryon densities. Through fragmentation of intense ion beams investigations with beams of short-lived radioactive nuclei far from stability will be possible. The addressed physics questions concern nuclear structure at the drip-lines, areas of astrophysics and nucleo-synthesis in supernovae and other stellar processes, as well as tests of fundamental symmetry. The structure of baryons and their limits of their existence is the interest of the two large experimental set-ups PANDA and CBM. Finally QED will be studied in extremely strong field effects and also the interaction of ions with matter. The future facility will feature a double-ring synchrotron SIS100/300 and a system of associated storage rings for beam collection, cooling, phase space optimisation and experimentation.
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Transparencies
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