Heavy-ion induced desorption yields of amorphous carbon filmsbombarded with 4.2     MeV / u lead ions

During the past decade, intense experimental studies on the heavy-ion induced molecular desorption were performed in several particle accelerator laboratories worldwide in order to understand and overcome large dynamic pressure rises caused by lost beam ions. Different target materials and various c...

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Bibliographic Details
Published in:Physical review special topics. PRST-AB. Accelerators and beams 2011-10, Vol.14 (10), p.101001, Article 101001
Main Authors: Mahner, E., Holzer, D., Küchler, D., Scrivens, R., Costa Pinto, P., Vallgren, C. Yin, Bender, M.
Format: Article
Language:English
Subjects:
Carbon
CERN
Desorption
Dynamic pressure
Electron clouds
Heavy ions
Injectors
Ion accelerators
Large Hadron Collider
Linear accelerators
Particle accelerators
Photoelectric emission
Proton beams
Stainless steels
Surface properties
Synchrotrons
Thin films
Vacuum chambers
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Summary:During the past decade, intense experimental studies on the heavy-ion induced molecular desorption were performed in several particle accelerator laboratories worldwide in order to understand and overcome large dynamic pressure rises caused by lost beam ions. Different target materials and various coatings were studied for desorption and mitigation techniques were applied to heavy-ion accelerators. For the upgrade of the CERN injector complex, a coating of the Super Proton Synchrotron (SPS) vacuum system with a thin film of amorphous carbon is under study to mitigate the electron cloud effect observed during SPS operation with the nominal proton beam for the Large Hadron Collider (LHC). Since the SPS is also part of the heavy-ion injector chain for LHC, dynamic vacuum studies of amorphous carbon films are important to determine their ion induced desorption yields. At the CERN Heavy Ion Accelerator (LINAC 3), carbon-coated accelerator-type stainless steel vacuum chambers were tested for desorption using 4.2MeV/u Pb54+ ions. We describe the experimental setup and method, present the results for unbaked and baked films, and summarize surface characterizations such as secondary electron yield measurements, x-ray photoemission spectroscopy, and scanning electron microscopy studies. Finally, we present a high-energy scaling of lead-ion induced desorption yields from the MeV/u to GeV/u range.
ISSN:1098-4402
1098-4402
2469-9888
DOI:10.1103/PhysRevSTAB.14.101001