1. Achieving Nominal Ion Beam PS Ion Progress
C. Carli and D. Manglunki on behalf of the I-LHC team
Status:
LEIR PS
SPS
In view of the Early LHC Ion Beam:
Actions
In view of the Nominal LHC Ion Beam:
Present Planning
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

2. Status (LEIR) Comments on the autumn 2006 run:
Vacuum leaks during preparations for the run:
(leak of high voltage feed through, exchange of electron cooler gun, bake-out incident, leak on cooler collector, … finally fixed with UHV varnish),
Thanks for all the efforts (workshop, AT/VAC teams, e-cooler team)
Magnetic cycle generation: temp. difficulties to make new lattice data available
Solved thanks to efforts from the LSA team.
Low level RF
re-commissioning (during “normal” start-up, had been considered an issue),
continuous development during run.
Very limited support from OP
AD run extended throughout PS commissioning
Strong perturbations of the start-up (and the run).
Early beam available without particular difficulties:
Apart injection efficiency fluctuations due to PS stray field (-> LEIR performance depending on PS cycle)
Some diagnostics missing/difficult:
ionisation profile monitors, profiles in ejection line, “old” system for Schottky diagnostics….
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

3. Status (LEIR)
In view of the nominal beam (schedule: “first exploratory studies”):
Nominal intensity accumulated,
Losses (not understood) at beginning of ramp, emittances NOT measured !!
Further studies (availability of measurements) required !!
Best we could obtain with the available resources.
80% of nom. intensity
accelerated on Oct. 13th
Nom. intensity at end of accumulation on Oct. 13th
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

4. Status (LEIR) LEIR operational status
reasonably reproducible (say like the PSB),
apart technical problems (vacuum ..), reasonably smooth start-up,
“early” beam for the PS provided without particular problems,
vacuum upgrades successful: studies on nominal beam not limited by life-time (small margin? – intensity saturated at less than twice the nominal one),
electron cooler works well (gun/collector spare situation is a concern).
Needs for consolidation/completion (emittance and other measurements, hardware, RF low level …)
Still some way to have the nominal LEIR beam available:
we did the best we could with the resources and time available,
(probably) not exhaustive list of issues:
improve accumulation rate (injection, Linac 3 current …),
better understanding of transverse damper,
understand losses at beginning of ramp (acceptances/emittances in all three planes, tune spreads ? …)
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

5. PS status
Planned (Aim at Early Beam, but hope to produce “quasi-nominal” beam):
21 days of parallel MD time (daytime only)
5 (out of 6 requested) periods of 8 dedicated hours
Achieved:
15 days of parallel MD time
In spite of difficult startup, LEIR beam only delayed by 2 days
4 days lost by subsequent breakdowns/faults from LINAC 3, LEIR, MPS
5 periods of 6 dedicated hours
Interventions inside PS (+30’ cooldown) needed for PI.SMH26 cooling and outside PS for F16.QFO205 control at beginning and end of each MD (see below)
Issues and Problems encountered:
SEMgrids in PS and TT2 (OK now)
Doubt on stripper movement (see shutdown work)
Recheck quadrupole polarities in TT2 (done during MD)
Insufficient current from one power supply (F16.QFO205) for low-b scheme 440A needed, 330A available, 400A available for dedicated MDs (see shutdown work)
New extraction optics from 2007 onwards (no PE.QKE58)
Java console Manager problems with PPMcopy, polluted CCVs
No Automatic Beam Steering (ABS) in TT2
Only 2 users (LHCION and MDION), 3 needed (Early, Nominal , Flat)
Resources mobilised by LHC proton beamS
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

6. PS status: Early beam [1]
Injection (in parallel)
First time right with computed currents
Lifetime measurements (in parallel)
Excellent vacuum + ion species => t>>700ms
LEIR-PS matching (2 dedicated MDs)
Still some V mismatch
Acceleration/Transition/Synchro
Only losses (25-50%) at field rise
All done in parallel whilst providing MD&OP beams
Ejection with old then new optics
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

7. PS status: Early beam [2]
(Limited) Low-b validation and Matching to TT2 (3 dedicated MDs)
Bonus: Transport through TT10 at the end of last dedicated MD
Thanks to LSA, no instrumentation
Design parameters practically achieved for Early Beam, but more stability needed
H=10.2 m V=6.9m
Parameter
Design
Achieved
Unit I
9.80
9.00
E9 charges N
1.20
1.1
E8 ions eH
0.55
0.47
p.mm.mrad eV
0.40
e*H
1.00
0.85 mm
e*V
0.73
e//
0.025
0.012
eVs/u tB
4.00
3.80 ns
Dp/p
0.65
0.30
E-3
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

8. PS status: Nominal beam (RF)
Reminder: same intensity/bunch as Early, but lots of gymnastics:
Batch expansion H16 -> H14 -> H12
Splitting H12 -> H24
Batch expansion 24 -> H21
Transition crossing, synchro to SPS and rebucketing at H169 as for Early Beam
Insufficient pick-up sensitivity to permit the radial loop to be closed until ~100ms after injection.
One 80MHz cavity is required for rebucketing, tuned to a different frequency from that for LHC protons. (i.e. no spare cavity for p+)
Sampled measurement of harmonic number did not work at the very lowest energies (realtime task?).
Splitting difficult at chosen energy (short bunches due to proximity to transition ). Good measured lifetime indicates we can lower it for the next attempts in 2007
Control of the relative phasing between the different harmonic components of the 10MHz system is an issue that must be addressed
Several more MDs will be required to complete the work on the nominal beam.
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

9. SPS Status
Early beam was sent to the entrance of the machine in November
Commissioning of the LHC ion beam planned for autumn 2007
Early LHC ion beam seen just upstream from SPS injection
Issues:
Complete the low level RF system on time for next autumn
Resources: time and manpower for ions while preparing LHC proton startup
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

10. In view of the Early LHC Ion Beam (List of Actions)
The Early beam has been produced in LEIR
Improve intensity reliability/reproducibility
Upgrades in the PS (planned for shutdown 06-07):
RF: radial loop pick-up sensitivity boost by 12dB (most probable cause of the ~30% losses seen at the start of acceleration)
Controls: ABS, PPM copy
Power supply for F16.QFO205 in TT2
Cooling water for PI.SMH26
Modification of stripper movement acquisition (outside vacuum)
SPS: beam knocked at the door but everything remains to be done; extensive dedicated MD period scheduled for autumn 2007
Inject on flat bottom, measure lifetimes
Accelerate through transition, synchronize on external frequency
Extraction
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

11. In view of the Nominal LHC Ion Beam (List of Actions)
Produce the Nominal beam in LEIR:
Improved diagnostics:
Renovate emittance measurement in the ring (ionization profile monitors),
Renovate emittane measurements of the LEIR to PS transfer line,
Verification of transverse dampers (and maybe other systems),
Increased Linac 3 current will help
Thorough (needs sufficient resources) optimizations (electron cooling, injection ……) and investigations to:
Produce the nominal LEIR beam and/or,
Understand and cure limitations.
Nominal scheme in the PS:
Complete the setting-up of the RF gymnastics (many harmonic number changes, “re-bucketing”, bunch splitting):
Can mostly be done with lower intensity,
Verification that it works with the nominal parameters (measure ejected beam).
SPS:
Investigate limitations (tune spreads, IBS) as soon as possible (autumn 2007) with “early beam” (nominal bunch population, just a longer plateau needed),
Leaves time to implement cures, in case limitations are encountered,
Setting up of accumulation of up to 52 LHC ion bunches of the nominal beam.
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki

12. In view of the Nominal LHC ion Beam (Present Planning …)
Autumn 2007:
In draft 2007 Accelerator Schedule:
Commissioning of the early beam in the SPS
MDs to investigate limitations of the SPS (IBS, DQSC) with the nominal beam scheduled
MDs to investigate limitations of the LHC (collimators) with the nominal beam proposed/scheduled.
In addition:
Studies in view of the nominal LHC Ion beam in LEIR,
Work on nominal scheme in the PS (resources ?)
MDs to be planned for 2008
First LHC ion run with early scheme in 2009
LHC Machine Advisory Committee, Dec 8th, ‘06
C. Carli & D. Manglunki