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| TUPCH173 |
Understanding of Ion Induced Desorption Using the ERDA Technique
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1423 |
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- M. Bender, H. Kollmus
GSI, Darmstadt
- W.A. Assmann
LMU, München
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In heavy ion synchrotrons like SIS18 at GSI high energetic ions can impact on the beam pipe and release gas molecules. This so called "ion induced desorption" deteriorates the accelerator vacuum and as a consequence the beam life time and luminosity. To minimize the pressure increase it is necessary to understand the physics of ion induced desorption. The elastic recoil ion detection analysis (ERDA) can give a time resolved element specific depth profile of a probe under ion bombardment. A UHV-ERDA setup has been installed at GSI to investigate correlations between desorption and material properties as well as its dose dependant evolution. Recent experiments have shown the influence of the surface state of a sample such as the oxide layer on steel as well as the importance of a high-purity bulk such as in silicon and OFHC copper. We will present the results of gold coated copper in comparison to stainless steel as applicable materials for accelerators.
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| TUPCH174 |
Vacuum Issues and Challenges of SIS18 Upgrade at GSI
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1426 |
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- H. Kollmus, M.C. Bellachioma, M. Bender, A. Kraemer, J. Kurdal, H.R. Sprenger
GSI, Darmstadt
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For the present experiment programm and for the planned FAIR facility the heavy ion synchroton SIS18 at GSI has to reach the space charge limit for highly and intermediate charged heavy ions. For the booster mode of SIS18 the number of 1x1012 ions per second in 4 Hz operation mode is specified. To achive this requirement a dynamic vacuum in the 10-12 mbar region has to be garanteed. The poster will present the status of recent R & D work concerning the SIS18 vacuum upgrade, with a focus on the new GSI NEG coating facility and on ion-induced desorption measurements using advanced ion beam analysis.
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