Ion desorption cross section of carbon containing molecules on aluminum and stainless steel
It was proposed that the ''pressure bump'' phenomenon observed in the CERN ISR proton machine is caused by ion induced desorption of gas molecules from the vacuum chamber wall.Residual gas molecules ionized by the proton beam are accelerated by the beam to wall potential (order of kV), and bombard the chamber wall with near normal incidence sputtering off molecules. Mass spectrometric analysis of the residual gas content showed that gas molecules desorbed during the pressure bump are mostly carbon containing molecules, e.g., carbon monoxide and hydrocarbons. Such evidence seems to indicate that carbon containing contamination adsorbed on the vacuum chamber wall may be one of the major contributors to the pressure bump. Both stainless steel and aluminum were proposed or used as the vacuum wall material for the recent generation of accelerators. ISR at CERN uses stainless steel and aluminum is being proposed for ISABELLE at Brookhaven. The ion induced desorption rates of carbon containing molecules from the surfaces of these materials were determined and are compared. (auth)
- Research Organization:
- Brookhaven National Lab., Upton, N.Y. (USA)
- NSA Number:
- NSA-33-001447
- OSTI ID:
- 4160745
- Report Number(s):
- BNL-20356; CONF-750737-3
- Resource Relation:
- Conference: Proceedings of the ISABELLE summer study, Upton, New York, USA, 14 Jul 1975; Other Information: Orig. Receipt Date: 30-JUN-76
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
N50230 -Metals
Ceramics
& Other Materials-Metals & Alloys-Properties
Structure & Phase Studies
430300* -Particle Accelerators-Auxiliaries & Components
*ALUMINIUM- SURFACE PROPERTIES
*STAINLESS STEELS- SURFACE PROPERTIES
*STORAGE RINGS- VACUUM SYSTEMS
*VACUUM SYSTEMS- MATERIALS
CARBON MONOXIDE
CERN ISR
COMPARATIVE EVALUATIONS
HYDROCARBONS
ISABELLE STORAGE RINGS