Integration of Absolute Cathode Position Encoding and Digital Indexing Control for use with MCSNICS Ion Sources

Mr Sean McNamer2, Dr Thomas Donoclift1, Stewart Freeman1, Richard Kitchen1

1SUERC, Glasgow, United Kingdom, 2NEC, ,

The SUERC AMS Laboratory has incorporated the use of new cathode wheel indexer controllers that are capable of interfacing with an optical, absolute positional encoding ring. The optical encoder and digital indexer controller work together to minimise indexing failures on our 134-multi-cathode SNICS ion sources, that would otherwise result in human intervention and delays to sample batch running. The absolute encoding ring utilises a diffraction grating that rotates with the cathode sample wheel. This encoded ring is then paired with a fixed sensor head that contains an analysing grating, a detector array, and a light source. The detector array can infer rotation direction, speed, and angular position of the encoded ring and thus determine the cathode wheel position. This information is used to recover from indexing failures without having to “home” the cathode wheel. The digital indexer controller functions more efficiently than the traditional indexer controller units and significantly speeds up indexing operations. The digital indexer controller unit also features a programmable micro controller with updatable farmwear via a USB connection. This allows useful movement operations and new features to be included in firmware updates as and when they are needed.


AMS Technician at the Scottish Universities Environmental Research Centre

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