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The 'SetupBeamFlag' indicates beams (typically with but not limited to low-intensities) that are used specifically during the initial setup of the BeamProductionChain. The definition derives from the experience and existing usage at LHC: too strict interlocks and rules that are required to ensure a safe and reliable high-intensity operation may at the same unnecessarily impact machine availability during beam setup with intensities that are considered safe.

The SetupBeamFlag facilitates the flexibility of masking some of these interlocks during setup operation with safe intensities, while ensuring that these interlocks are taken automatically into account when operating with unsafe (typically high-intensity) beams.

The SetupBeamFlag is a continuous signal and defined per circular accelerator with the source being typically the preceding accelerator. The flag needs to be derived automatically from the beam current transformer (simple threshold). Most of the SetupBeamFlag -maskable interlock candidates are related to more complex or beam-instrumentation-derived interlocks such as beam transmission, beam loss monitoring, beam screens and multi-wire grids.

Some use-cases and proposed rule examples to illustrate the SetupBeamFlag are:
  • While 20% beam transmissions may be temporarily acceptable during setup or low-intensity operation (ie. transmission interlock being masked), the associated interlock should not be kept permanently disabled or forgotten once moving to high-intensity operation.
  • In order to self-protect sensitive beam screens, wire-grids and other similar devices, these devices would by-default create an extraction (or injection) interlock (↔fail-safe logic) whenever they are inserted into the beamline or ring. However, these interlock could be masked if the 'SBF==true' and possibly other additional beam mode requirements are fulfilled (e.g. not in 'STABLE BEAMS' or 'INTENSITY RAMP-UP', etc.).
Provisionally, it is foreseen to derive the SetupBeamFlag from a simple (coarse) threshold using one of the DC beam current transformer in each of the ring accelerators. The SBF is propagated and defined for all devices within the ring where it is measured, its subsequent transfer-lines, up to the next ring accelerator or beam target.


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