Scrubbing Run: TDI, MKI and MKE interlocks

Chiara Bracco, Jan Uythoven

ABT/BTPAcknowledgments: T. Baer, M. Barnes, E. Carlier

Scrubbing Run with 25 ns beam 4/10-8/10 Scrubbing run:

Injection and accumulation of trains of 144-288 bunches Long periods without injections The TDI has to be retracted to parking position if vacuum worse than given threshold

Proposal to be confirmed:1E-7 in IP2 and 1E-8 in IP8 Announcer advising when limit exceeded?

Make special scrubbing sequence for topping up. Put MKI in STANDBY before moving out the TDI

Risk of MKI erratics with TDI retracted ?

TDI interlocks: injection inhibit if TDI jaws open to parking (injection BIS) no beam permit inhibit to charge the MKI PFN and no pre-pulse trigger no erratics

In case the MKI PFN gets charged and then the TDI moved out before pulsing:MKI interlocks : “NO-TRIGGER PULSE” the PFN gets discharged through the dump switch ~2.5 ms after the injection pre-pulse

Risk of extraction from SPS with TDI retracted ?

TDI interlocks: SPS extraction inhibit if TDI jaws open to parking (injection BIS) no beam permit inhibit to charge the MKE PFN and no pre-pulse trigger no erratics

In case the MKE PFN gets charged and then the TDI moved out before pulsing (15 ms window!):

MKE interlocks: “NO-TRIGGER PULSE”. MKE4 will be discharged by clipper switch. No clipper switch in point 6 resulting in minutes to discharge, however:

MKE6 running at half nominal voltage, unlikely to perform erratic TDI will only have moved by few microns in those 15 ms

Additional Slide

UFO Proposal during scrubbing (Tobias) If vacuum pressure at TDI below following limits: Move in TDI.

Limit for TDI B1: 1e-7 mbar at VGPB.231.4L2.X (tbc) Limit for TDI B2: 1e-8 mbar at VGPB.231.4R8.C (tbc)

If MKI vacuum pressure below SIS injection interlock: Disable SPS MKE in order to avoid beam extraction. Load timing table: INJECTION_BI_MD, Switch to BLM Study Buffer Enable MKI. Request via the LHC injection sequencer the next nominal injection.

Beam will be accelerated but not extracted from the SPS (dump on SPS internal dump at end of cycle)

MKIs will pulse at gap for next nominal injection. Repeat above about 10 times.

Load timing table: INJECTION_BI, switch to IQC Buffer Enable SPS MKE for nominal injection. Do nominal injection. If MKI vacuum pressure below SIS injection interlock:

Disable SPS MKE in order to avoid beam extraction. Load timing table: INJECTION_BI_MD, Switch to BLM Study Buffer. Request via the LHC injection sequencer the next nominal injection. Repeat above about 10 times.

Put MKI to standby. Retract TDI.