1. Interlocking of CNGS (and other high intensity beams) at the SPS
J. Wenninger AB-OP
SPS Machine Operation
(Future) SPS beams
HW interlock systems for the LHC area
Extraction interlocking
CNGS Review June 04 / J. Wenninger

2. CNGS Review June 04 / J. Wenninger
A bit of terminology
Hardware interlocks :
are triggered via hardware connections.
have a direct connection to dump / extraction kickers.
must be fail-safe.
are required for fast decisions.
fast local processing.
Software interlocks :
managed by a central “program”.
not fail-safe, but more flexible.
involve more complex analysis.
provide redundancy & diagnostics.
 both types of interlocks exist presently at the SPS and will be required in the future.
Fast abort
“slow” beam stop
(injectors…)
CNGS Review June 04 / J. Wenninger

3. CNGS Review June 04 / J. Wenninger
Future SPS beams
All future SPS beams are high intensity beams :
LHC × 1013 p
CNGS > 4 × 1013 p
Fixed Target > 2 × 1013 p
SPS operation must be very flexible.
“fast” cycle / beam configuration changes.
As a part of the consolidation of the SPS for LHC & CNGS, the interlock system(s) are also renovated.
The existing hardware and software interlock systems cannot be extended / cannot cope with the new constraints.
The new HW interl. concept is a COMMON development for SPS & LHC – same components :
Need tight coupling LHC – SPS.
Allows benchmarking of the LHC components at the SPS.
Saves resources…
Machine must be
protected from beam
induced damage !
CNGS Review June 04 / J. Wenninger

4. (Future) SPS extractions
North Area
(Slow Extr.)
LHC Ring 2 + CNGS (Fast Extr.)
LHC Ring 1 (Fast Extr.)
CNGS Review June 04 / J. Wenninger

5. HW Interlock Architecture
The HW is composed of Beam Interlock Modules (BIC) that collect (logical) interlock signals from the clients :
Standard interface to all clients – clients deliver logic signals OK / not OK.
Safe signal transmission & handling with positive AND negative logic.
Distributed system : different BICs are connected together via interlock loops.
Diagnostics : each signal change is logged with ~msec accuracy (GPS timing). …
Architecture of the future HW Interlock system for SPS
Extraction intlk.
for LHC ring2 / CNGS
 extraction kicker
Interlock loop
for SPS ring
 beam dump
CNGS Review June 04 / J. Wenninger

6. Interlocks for fast extractions
Fast extractions of high intensity beams are very delicate since one must be sure in advance that the line is in perfect shape :
All critical elements must be surveyed before the moment of extraction.
The survey should be performed ‘as late as possible’ to minimize the time interval over which things can go wrong (PC trips…) :
For the CNGS & LHC extraction surveying will be performed 4-20 ms before EACH extraction.
Problems on the first CNGS extraction will inhibit the second extraction.
CNGS Review June 04 / J. Wenninger

7. Power converter surveillance principle
time window
Window
magnet current
n sec
time
current
Start cycle
Extraction
Extraction enable
CNGS Review June 04 / J. Wenninger

8. Interlock list… SPS ring & extraction : Lines : HW interlocks
Bumped beam position (extraction bump + SPS CO).
Bumper magnet current (extraction bump).
Extraction kicker.
Magnetic septum.
Lines :
Vacuum valves.
Power converter currents.
Beam losses ( inhibit second CNGS extraction).
… (whatever will come up)
no extraction !
Last moment for decision < 1 ms before kicker fires.
SW interlocks
Beam loss.
Beam trajectory.
Beam profile.
Horn state, target temperatures… …
Stop beam in injectors, prevent injection. Wait for operator action…
CNGS Review June 04 / J. Wenninger

9. LSS4 IS special The only SPS extraction with 2 different beams…
CNGS +
LHC
The only SPS extraction with 2 different beams…
CNGS
Interlocks are grouped into geographical and logical areas.
Each area is controlled by one (or more) BIC module(s).
A master module is used to select the appropriate inputs depending on the beam type (LHC or CNGS) and on the status of the DUMPs – based on machine slow timing.
LHC
CNGS Review June 04 / J. Wenninger

10. CNGS Review June 04 / J. Wenninger
Summary & status
The CNGS & LHC extraction channels & lines will be interlocked to prevent any beam induced damage :
Due to limitations of the equipment used to generate interlocks, we have a few ms time interval before extraction where we are ‘blind’. Studies to reduce this gap for the most critical (fast time constants) magnet/PC circuit (magnetic septum) are under way…
The interlock system HW provides sufficient inputs in case additional interlocks have to be added in the future.
The interlock system was tested succesfully in 2003 during an extraction test with LHC beam (LSS4 and TT40 line). An improved system will be operational for the CNGS & LHC extraction tests in the fall.
The complete extraction interlock system will be in place in 2006.
The software interlock system is not yet well defined : depends on progress with the new SPS control system.
CNGS Review June 04 / J. Wenninger