MEASUREMENTS ON SLAC LINAC RF SYSTEM FOR LCLS OPERATION. PDF Download
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Languages : en
Pages : 3
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The Linac Coherent Light Source (LCLS) project [1] at SLAC uses a dense 15 GeV electron beam passing through a long undulator to generate extremely bright x-rays at 1.5 angstroms. The project requires electron bunches with a nominal peak current of 3.5kA and bunch lengths of 0.020mm (70fs). The RF stability required by the bunch compressors is tighter than what is currently required to run experiments. Measurements to determine how well the existing linac will meet the new requirements are ongoing. Presented is an update on the measurements and how they pertain to LCLS.
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Languages : en
Pages : 3
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Book Description
The Linac Coherent Light Source (LCLS) project [1] at SLAC uses a dense 15 GeV electron beam passing through a long undulator to generate extremely bright x-rays at 1.5 angstroms. The project requires electron bunches with a nominal peak current of 3.5kA and bunch lengths of 0.020mm (70fs). The RF stability required by the bunch compressors is tighter than what is currently required to run experiments. Measurements to determine how well the existing linac will meet the new requirements are ongoing. Presented is an update on the measurements and how they pertain to LCLS.
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Languages : en
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The authors describe the possible use of the SLAC linac to drive a unique, powerful, short wavelength Linac Coherent Light Source (LCLS). Using the FEL principle, lasing is achieved in a single pass of a high peak current electron beam through a long undulator by self-amplified-spontaneous-emission (SASE). The main components are a high-brightness electron RF gun with a photocathode, two electron bunch length compressors, the existing SLAC linac, beam diagnostics, and a long undulator combined with a FODO quadrupole focusing system. The RF gun, to be installed about 1 km from the end of the SLAC linac, would produce a single bunch of 6 x 10[sup 9] electrons with an invariant emittance of about 3 mm-mrad and a bunch length of about 500 [mu]m. That bunch is then accelerated to 100 MeV and compressed to a length of about 200 [mu]m. The main SLAC linac accelerates the bunch to 2 GeV were a second bunch compressor reduces the length to 30--40 [mu]m and produces a peak current of 2--3 kA. The bunch is then accelerated to 7--8 GeV and transported to a 50--70 m long undulator. Using electrons below 8 GeV, the undulator could operate at wavelengths down to 2 nm, producing about 10 GW peak power in sub-ps light pulses. At a linac repetition rate of 120 Hz, the average power is about 1 W. Linac operation at lower beam energies provides longer wavelength radiation. After the undulator, the beam is deposited in a dump. The LCLS light pulses are then distributed to multiple user stations using grazing incident mirrors. Length compression, emittance control, phase stability, FEL design criteria, and parameter tolerances are discussed. A demonstration experiment is also described which uses the SLAC linac and (possibly) the PALADIN undulator to study SASE to power saturation at wavelengths of 40--360 nm.
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Languages : en
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Author:
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Languages : en
Pages : 4
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The Linac Coherent Light Source (LCLS) at SLAC will be the brightest X-ray laser in the world when it comes on line. In order to achieve the brightness a 200fS length electron bunch is passed through an undulator. To create the 200fS, 3kA bunch, a 10pS electron bunch, created from a photo cathode in an RF gun, is run off crest on the RF to set up a position to energy correlation. The bunch is then compressed by chicanes. The stability of the RF system is critical in setting up the position to energy correlation. Specifications derived from simulations require the RF system to be stable to below 200fS in several critical injector stations and the last kilometer of linac. The SLAC linac RF system is being upgraded to meet these requirements.
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Languages : en
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Book Description
The Linac Coherent Light Source (LCLS) project at SLAC uses a dense 15 GeV electron beam passing through a long undulator to generate extremely bright x-rays at 1.5 angstroms. The project requires electron bunches with a nominal peak current of 3.5kA and bunch lengths of 0.020mm (70fs). The bunch compression techniques used to achieve the high brightness impose challenging tolerances on the accelerator RF phase and amplitude. The results of measurements on the existing SLAC linac RF phase and amplitude stability are summarized and improvements needed to meet the LCLS tolerances are discussed.
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Languages : en
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The Linac Coherent Light Source (LCLS) at SLAC is in full user operation and has met the stability goals for stable lasing. The 250pC bunch can be compressed to below 100fS before passing through an undulator. In a new mode of operation a 20pC bunch is compressed to about 10fS. Experimenters are regularly using this shorter X-ray pulse and getting pristine data. The 10fS bunch has timing jitter on the order of 100fS. Physicists are requesting that the RF system achieve better stability to reduce timing jitter. Drifts in the RF system require longitudinal feedbacks to work over large ranges and errors result in reduced performance of the LCLS. A new RF system is being designed to help diagnose and reduce jitter and drift in the SLAC linac.
Author: Eisuke J. Minehara
Publisher: Newnes
ISBN: 0080930859
Category : Science
Languages : en
Pages : 800
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Book Description
This book contains the Proceedings of the 25th International Free Electron Laser Conference and the 10th Free Electron Laser Users Workshop, which were held on September 8-12, 2003 in Tsukuba, Ibaraki in Japan.
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Languages : en
Pages : 3
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The beam quality and operational requirements for the Linac Coherent Light Source (LCLS) currently being constructed at SLAC are exceptional, requiring the design of a new RF photocathode gun for the electron source. Based on operational experience at SLAC's GTF and SDL and ATF at BNL as well as other laboratories, the 1.6cell s-band (2856MHz) gun was chosen to be the best electron source for the LCLS, however a significant redesign was necessary to achieve the challenging parameters. Detailed 3-D analysis and design was used to produce near-perfect rotationally symmetric rf fields to achieve the emittance requirement. In addition, the thermo-mechanical design allows the gun to operate at 120Hz and a 140MV/m cathode field, or to an average power dissipation of 4kW. Both average and pulsed heating issues are addressed in the LCLS gun design. The first LCLS gun is now fabricated and has been operated with high-power RF. The results of these high-power tests are presented and discussed.
Author: K.-J. Kim
Publisher: Newnes
ISBN: 0080930425
Category : Science
Languages : en
Pages : 727
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Book Description
This book contains the Proceedings of the 24th International Free Electron Laser Conference and the 9th Free Electron Laser Users Workshop, which were held on September 9-13, 2002 at Argonne National Laboratory. Part I has been reprinted from Nucl. Instr. and Meth. A 507 (2003), Nos. 1-2.
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Languages : en
Pages : 5
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The Linac Coherent Light Source that is under development at SLAC will become the world's first x-ray free electron laser. This laser will enable revolutionary studies in many different areas of science. Before the laser goes into operation at SLAC, phase noise measurements need to be taken to determine whether the existing linac structure will be able to run the LCLS. The phase noise of a system is translated into timing jitter, and the LCLS can only tolerate a certain amount of jitter. The measurements taken on the linac were higher than expected and we hypothesized that our measuring devices might have been the source of high noise readings. After designing new low noise amplifiers to amplify the signal, the phase noise and timing jitter levels went down. We were able to target the PEP phase shifter as the component of the linac system that was adding a lot of noise. More work needs to be done to further reduce the phase noise and timing jitter levels.
