A new Wall Current Monitor (WCM) to replace the existing one
in SS03.
It is intended for use by the PS Beam Shape Monitor and longitudinal tomography instruments.
The WCM is designed to have a flat frequency response from 100kHz to 3GHz.
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The design of the new monitor resembles more that of the a similar device in PS SS95. It consists of a cylindrical cavity enclosing a gap in the standard PS elliptical vacuum chamber (Fig.1). The cavity contains five T240/160/20-8C11 ferrite rings and the inside metal surfaces are lined with PLT100/100/6-4S60 ferrite tiles. The rings serve to obtain a lower cut-off frequency of about 100kHz, while the tiles absorb cavity resonances and reflections. At eight points around the gap in the inner chamber (Fig.2), the signal is picked off and taken out through impedance-matched vacuum feedthroughs. The pick-off points are spaced at equal angles of 45°.
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| Fig.1: Cross section of an EM simulation model of the WCM |
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| Fig.2: Placement of pick-off points along elliptical vacuum chamber edge |