DESIGN OF ULTRA HIGH VACUUM (UHV) SYSTEM TO EVALUATE OUTGASSING RATE OF THE MATERIALS TO ASSES THEIR UHV COMPATIBILITY

Stainless steel and copper are very suitable structural metals for fabrication of UHV vessels. Indus - 1 (450MeV) and Indus - 2(2.5GeV) are electron storage rings dedicated for their application as a synchrotron radiation sources. In accelerators the residual gas particles limit the e - beam performance and its life time. The main factor deciding the UHV compatibility of any vacuum component is the specific outgassing rate, at room temperature and specifically at the operating temperature. To evaluate the outgassing rate of the various materia ls to be used in UHV, an experimental set - up made up of stainless steel has been designed, developed and tested. A thin cylindrical shell under external pressure, like a column, may collapse either by yield or by buckling. Collapse by yield is caused by st resses in the shell reaching the yield point of the material. Collapse by buckling is caused by buckling of the shell at stresses which may be considerably below the yield point. The shell strength i.e. the thickness of the considered experimental set ? up chambers was designed on the basis of ASME code section VIII/Div - 1, II/part - D. Orifice was designed as per AVS standard. The buckling analysis, deflection analysis and stress analysis were also performed on the experimental set - up chambers using ANSYS soft ware and results were found up to the mark. This paper elaborates design calculations for chamber and orifice, outgassing - rate measurements and the ANSYS results