GATT: Gas Attenuator

More details on the gas attenuator system can be found at Standard Operation of SASE3 Gas Attenuator.

Operation

With the new EPS Interlock based on the pre-absorber, the 2mbar policy is obsolete. Pausing the gas injection can be done differently depending how long the injection will be paused:

  1. Pause Injection. Useful when fast cycling among “full transmission” and any other Tr<100% (daily routine on both instruments). In this situation P_GATT minimum pressure would be only in the 10-4 mbar range (at best).
  2. Stop Injection. If the next injection is not expected to happen in the next 1 hour or more. P_GATT would reach UHV conditions (P in the 10-8 mbar range), but the booster pumps remain active (only isolated from the beamline).
  3. Return to UHV. If the next injection is not expected to happen in 12hrs or more (i.e. before Shutdowns, Fac. Development weeks, Monday mornings, etc..) This would “transform” GATT in a standard Beamline vacuum sector and can be consider the SAFEST status for the device and the beamline (Gas Injection is Interlocked, Booster Pumps will be isolated and stopped).

More details can be found in the Technical Note SASE3 Gas Attenuator Device PLC Interlock System.