| Paper |
Title |
Page |
| MOPCH161 |
Development of a Prototype Superconducting CW Cavity and Cryomodule for Energy Recovery
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436 |
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- P.A. McIntosh, C.D. Beard, D.M. Dykes, B. Todd
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- S.A. Belomestnykh
Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
- A. Buechner, P. Michel, J. Teichert
FZR, Dresden
- J.M. Byrd, J.N. Corlett, D. Li
LBNL, Berkeley, California
- T. Kimura, T.I. Smith
Stanford University, Stanford, Califormia
- M. Liepe, V. Medjidzade, H. Padamsee, J. Sears, V.D. Shemelin
Cornell University, Ithaca, New York
- D. Proch
DESY, Hamburg
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Energy Recovery LINAC (ERL) and LINAC-driven FEL proposals and developments are now widespread around the world. Superconducting RF (SRF) cavity advances made over the last 10 years for TESLA/TTF at 1.3 GHz, in reliably achieving accelerating gradients >20 MV/m, suggest their suitability for these ERL and FEL accelerators. Typically however, photon fluxes are maximised from the associated insertion devices when the electron bunch repetition rate is as high as possible, making CW-mode operation at high average current a fundamental requirement for these light sources. Challenges arise in controlling the substantial HOM power and in minimizing the power dissipated at cryogenic temperatures during acceleration and energy recovery, requiring novel techniques to be employed. This paper details a collaborative development for an advanced high-Qo cavity and cryomodule system, based on a modified TESLA cavity, housed in a Stanford/Rossendorf cryomodule. The cavity incorporates a Cornell developed resistive-wall HOM damping scheme, capable of providing the improved level of HOM damping and reduced thermal load required.
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| MOPLS020 |
Rad-hard Luminosity Monitoring for the LHC
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580 |
| |
- A. Ratti, J.-F. Beche, J.M. Byrd, K. Chow, S. De Santis, P. Denes, B. Ghiorso, H.S. Matis, M. T. Monroy, W.C. Turner
LBNL, Berkeley, California
- E. Bravin
CERN, Geneva
- P.F. Manfredi
Pavia University, Engineering faculty, Pavia
- W. Vandelli
Pavia University, Pavia
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Luminosity measurements at the high luminosity points of the LHC are very challenging due to the extremely high radiation levels in excess of 1 GGy/yr. We have designed an ionization chamber that uses a flowing gas mixture and a combination of metals and ceramics. With such a choice, an additonal challenge is achieving the necessary speed to be able to resolve bunch-by-bunch luminosity data. We present the design, analysis and experimental results of the early demonstration tests of this device.
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| TUPCH100 |
Fiberoptics-based Instrumentation for Storage Ring Longitudinal Diagnostics
|
1247 |
| |
- S. De Santis, J.M. Byrd, A. Ratti, M.S. Zolotorev
LBNL, Berkeley, California
- Y. Yin
Y.Y. Labs, Inc., Fremont, California
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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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| TUPCH101 |
Modeling of Ultrafast Streak Cameras
|
1250 |
| |
- G. Huang, J.M. Byrd, J. Feng, H.A. Padmore, J. Qiang, W. Wan
LBNL, Berkeley, California
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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.
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| THPCH066 |
Transient Beam Loading in the DIAMOND Storage Ring
|
2937 |
| |
- S. De Santis, J.M. Byrd
LBNL, Berkeley, California
- R. Bartolini
Diamond, Oxfordshire
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Harmonic cavity systems have been installed on several 3rd generation light sources to lengthen the bunches and increase the Touschek lifetime. Apart from this beneficial effect, harmonic cavities are known to increase the transient beam loading in high-current machines, due to the presence of gaps in the fill pattern. The amplitude of this effect, which is substantially larger than that caused by the main RF system, can in turn produce considerable variations in bunch length and phase along the train, which result in a significant reduction of the lifetime increase. We have developed a tracking simulation, which we have applied to the analysis of the beam loading transients in Diamond, for the case of passive superconducting harmonic cavities. The influence of beam current, gap amplitude and harmonic cavity tuning on the final lifetime have been studied, as well as the effects of higher-order modes.
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| THPCH067 |
Coherent Synchrotron Radiation Studies at the Accelerator Test Facility
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2940 |
| |
- S. De Santis, J.M. Byrd
LBNL, Berkeley, California
- A. Aryshev, T. Naito, J. Urakawa
KEK, Ibaraki
- M.C. Ross
SLAC, Menlo Park, California
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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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| THPCH130 |
Design and Implementation of Analog Feedback Damper System for an Electron-proton Instability at the Los Alamos Proton Storage Ring
|
3104 |
| |
- C. Deibele, S. Assadi, V.V. Danilov, S. Henderson, M.A. Plum, C. Sibley III
ORNL, Oak Ridge, Tennessee
- S. Breitzmann, S.-Y. Lee
IUCF, Bloomington, Indiana
- J.M. Byrd
LBNL, Berkeley, California
- J.D. Gilpatrick, R.J. Macek, R.C. McCrady, J.F. Power, J. Zaugg
LANL, Los Alamos, New Mexico
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The PSR (Proton Storage Ring) at LANSCE has observed an E-P (electron-proton) instability. A wideband analog feedback damper system was designed and implemented that has shown it is possible to correct this instability. The damper system consists of two 180 degree hybrids, low level amplifiers, a delay line, comb filter, power amplifiers, and adjustable delay lines. The system bandwidth is about between 10-300 MHz, and was developed and implemented in stages showing improvement in the e-p threshold of the buncher voltage. The system takes advantage of fiber optic technology for delays as well as for the comb filter. A system description and some measurement results are presented.
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