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Introduction
Given the high stability requirements of KPF, the main spectrometer sits within a vacuum chamber in order to isolate the spectrometer from its environment. This provides isolation against changes in atmospheric pressure and also convective thermal disturbances.
The vacuum pump system for the KPF vacuum chamber consists of a turbo pump backed by a roots pump. The Leybold TurboVac pump is controlled via a Leybold Turbo.Control controller, which contains a webserver to allow control of the pump via a webpage in a browser. The Leybold EcoDry roots pump is not under remote control; within KPF we turn it simply turned on and off via a PDU outlet on the Vac Cart.
Within KPF the turbo and roots pump run continuously.
The Turbo.Control controller also allows connection of two vacuum gauges; we use both of these ports to connect a low and a high vacuum gauge. These two gauges monitor the vacuum pressure within the pipe going to the main KPF vacuum chamber. They are mounted on the Vac Cart and sit on the Vac Cart side of the main chamber gate valve.
Direct computer control of the TurboVac pump is possible via serial commands, however creating a full KTL dispatcher for the pump was deemed too difficult given the dozens of commands required, as well as the failsafes fail-safes required to not damage the pump. As such we decided to use the vendor-supplied web-based software to control the pump, which has all the features we need built-in. This Since this webpage also provides pump telemetry, and we wrote a KPF KTL dispatcher monitors to monitor this webpage and recorders write telemetry values to KTL keywords.
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