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| MOBAU01 |
Status of the Linac Coherent Light Source
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22 |
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- D. Dowell
SLAC, Menlo Park, California
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The world's first x-ray free electron laser, the Linac Coherent Light Source (LCLS), is currently under construction at the Stanford Linear Accelerator Center (SLAC). This facility uses the last kilometer of the SLAC 3 km Linac to produce 1.5 to 15 angstrom photons in a 100 meter long undulator with up to15 GeV electrons. The production of the high-brightness electron beam requires the construction of a new RF photocathode gun and a 135 MeV injector at the 2/3 point of the SLAC Linac. In addition, two stages of chicane compressors will be installed for compressing the electrons to a 22 micron bunch length, boosting the peak current to 3.5 kiloamperes. The bright, dense electron bunches then radiation via the SASE process in the long undulator. The coherent x-ray beam propagates through a gas attenuator and various diagnostics, before delivery to the experimental stations in the Far Hall. The design features and status of this novel facility will be presented.
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Slides
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Talk
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| THPPH063 |
In-Situ Cleaning of Metal Photo-Cathodes in RF Guns
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732 |
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- J. F. Schmerge, J. Castro, J. E. Clendenin, E. R. Colby, D. Dowell, S. M. Gierman, H. Loos, M. Nalls, W. E. White
SLAC, Menlo Park, California
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Cu cathodes installed in rf guns typically exhibit much lower quantum efficiency than the theoretical limit. Experimenters often use some sort of in situ technique to "clean" the cathode to improve the QE. The most common technique is laser cleaning where the laser is focused to a small spot and the laser is scanned across the cathode. However, this can also damage the cathode since the laser is operated near the damage threshold and the QE degrades over days and must be cleaned regularly. Alternatively Hydrogen ion beams can be used to clean the cathode and improve the QE but this cleans only the area exposed to the ion beam. In this paper we measure the QE and the dark current emitted from a cathode before and after exposing the gun to a hydrogen plasma created with an rf discharge. With this technique the entire surface of the gun is cleaned simultaneously with no apparent detrimental effects.
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