Post on 28-Dec-2015
1R.G. – 17/03/2003 MORIOND Workshop 2003
The SPL* at CERNThe SPL* at CERN
OUTLINEOUTLINE
Why ? Why ? How ?How ? RoadmapRoadmap SummarySummary
* SPL = Superconducting Proton LinacA concept for improving the performance of the proton beams at CERN, A concept for improving the performance of the proton beams at CERN, ultimately based on a high-energy Superconducting Linear Acceleratorultimately based on a high-energy Superconducting Linear Accelerator
2R.G. – 17/03/2003 MORIOND Workshop 2003
The SPL Working GroupThe SPL Working Group
- Conceptual Design of the SPL, a High Power Superconducting Proton Linac at CERN, ed. M. Vretenar, CERN 2000-012
- SPL web site: http://cern.web.cern.ch/CERN/Divisions/PS/SPL_SG/
REFERENCES
3R.G. – 17/03/2003 MORIOND Workshop 2003
(from CERN/SPC/811)
Period of interest…
LHC
SPSFixedtarget
PSB&
PS
14 CERN/SPC/811CERN/FC/4567
= Approved = UnderConsideration
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
LHCATLAS
CMS
ALICE
LHCb
Other LHC experiments
(e.g. TOTEM)
SPSHeavy ions
COMPASS
NA48
Test Beams
North Areas
West Areas
Neutrino / CNGS
Other FacilitiesTOF Neutron
AD
ISOLDE
CAST
DIRAC
HARP
Test beams
East Hall
R&D(Detector & Accelerator)
Long–term Scientific Long–term Scientific Programme at CERNProgramme at CERN
4R.G. – 17/03/2003 MORIOND Workshop 2003
To consolidate the injectors’complex and be ready to provide enough To consolidate the injectors’complex and be ready to provide enough protons to all usersprotons to all users
Why ?Why ?
For the approved physics programmes:For the approved physics programmes:
PS supercyclefor LHC
PS supercyclefor CNGS Remaining PSB & PS
pulses to be shared between nTOF, AD, ISOLDE, East Hall,Machine studies…
5R.G. – 17/03/2003 MORIOND Workshop 2003
Because higher beam performance (brightness*) will be first, Because higher beam performance (brightness*) will be first, welcome, and later, necessary to:welcome, and later, necessary to:
Reliably deliver the ultimate beam actually foreseen for LHC, Reduce the LHC filling time, Increase the proton flux onto the CNGS target, Increase the proton flux to ISOLDE, Prepare for further upgrades of the LHC performance beyond the present ultimate.
Why ?Why ?
* For protons, brightness can only degrade along a cascade of accelerators Any improvement has to begin at the low energy (linac) end
For the approved physics programmes:For the approved physics programmes:
6R.G. – 17/03/2003 MORIOND Workshop 2003
Neutrino Physics with a successive set of instruments of increasing Neutrino Physics with a successive set of instruments of increasing complexity:complexity:
Super-Beam (= conventional but very intense
proton beam) generating an intense neutrino flux
towards a remote (~ 150 km) underground experiment “beta” beams generating electron neutrinos and
anti-neutrinos towards the same underground experiment Neutrino Factory sending neutrinos to very remote
(up to 3000 km) underground experiment(s)
Nuclear Physics with a Radio-Active Ion Beam Facility of the second Nuclear Physics with a Radio-Active Ion Beam Facility of the second generation ?generation ?
Why ?Why ?
For possible new physics programmes:For possible new physics programmes:
7R.G. – 17/03/2003 MORIOND Workshop 2003
For improvements of the present accelerator complex, the For improvements of the present accelerator complex, the energy of the linac injecting into the first synchrotron has to be energy of the linac injecting into the first synchrotron has to be increased (50 MeV today)increased (50 MeV today)
Comparing a Linac + fixed energy rings set-up with a 2-3 GeV Comparing a Linac + fixed energy rings set-up with a 2-3 GeV Rapid Cycling Synchrotron (RCS) :Rapid Cycling Synchrotron (RCS) : The linac set-up can accommodate more users since its beam power can be
increased, Some users prefer the long beam pulse delivered by a linac, The RCS construction cost could be smaller, but this is moderated by the
availability of the LEP RF equipment which a linac will re-use Linac maintenance is likely to require less manpower
Why a high energy linac ?Why a high energy linac ?
8R.G. – 17/03/2003 MORIOND Workshop 2003
A large inventory of LEP RF equipment is available (SC cavities, cryostats, klystrons, waveguides, circulators, etc.)which can drastically reduce the cost of construction
LEP cavity modules in storage
Stored LEP klystrons
11R.G. – 17/03/2003 MORIOND Workshop 2003
SPL design parametersSPL design parameters
H-
RFQ RFQ1 chop. RFQ2 RFQ1 chop. RFQ2 0.52 0.7 0.8 dump
Source Low Energy section DTL Superconducting section
45 keV 3 MeV 120 MeV 2.2 GeV
40MeV 237MeV
6 m 64 m 584 m
PS / Isolde
Stretching andcollimation line
Accumulator Ring
Debunching
383MeV
668 m
DTL CCDTLchopping
For neutrino physics, it has to be compressed with an
Accumulator and aCompressor ring into
140 bunches, 3 ns long,forming a burst of 3.3 s
Ion species H-Kinetic energy 2.2 GeVMean current during the pulse 13 mADuty cycle 14.0 %Mean beam power 4 MWPulse frequency 50 HzPulse duration 2.80 msDuty cycle during the beam pulse 61.6 %Maximum bunch current 22.7 mABunch length (total) 0.5 nsEnergy spread (total) 0.5 MeVNormalised rms horizontal emittance 0.4 mm mradNormalised rms vertical emittance 0.4 mm mradLongitudinal rms emittance (352 MHz) 0.3 deg MeV
12R.G. – 17/03/2003 MORIOND Workshop 2003
Accumulator and Compressor Accumulator and Compressor Rings (“PDAC”)Rings (“PDAC”)
T= 2.2 GeVIDC = 13 mA (during the pulse)IBunch= 22 mA3.85 108 protons/bunchlb(total) = 44 ps*H,V=0.6 m r.m.s
(140 + 6 empty)per turn
845 turns( 5 140 845 bunches per pulse)
no beam
2.8 ms
20 ms
140 bunches
20 ms
3.2 s
Charge exchangeinjection
845 turns
PROTON ACCUMULATORTREV = 3.316 s
(1168 periods @ 352.2 MHz)
1 ns rms(on target)
22.7 ns
TARGET
H+140 bunches1.62 1012 protons/bunchlb(rms) = 1 ns (on target)
Fast ejection
KICKER20 ms
3.3 slb(total) = 0.5 ns
DRIFT SPACE+
DEBUNCHER
H-
11.4 ns
22.7 ns
5bunches
Fast injection(1 turn)
BUNCH COMPRESSORTREV = 3.316 s
(1168 periods @ 352.2 MHz)
BUNCHROTATIONRF (h=146)
Fast ejection
RF (h=146)
3 emptybuckets
17.2 ms
2 synchrotron ringsin the ex-ISR tunnel
13R.G. – 17/03/2003 MORIOND Workshop 2003
H-
RFQ RFQ1 chop. RFQ2 RFQ1 chop. RFQ2 0.52 0.7 0.8 dump
Source Low Energy section DTL Superconducting section
45 keV 3 MeV 120 MeV 2.2 GeV
40MeV 237MeV
6 m 64 m 584 m
PS / Isolde
Stretching andcollimation line
Accumulator Ring
Debunching
383MeV
668 m
DTL CCDTLchopping
SPL designSPL design
Input Output No. of Peak RF No. of No. of No. of Lengthenergy energy cavities power klystrons tetrodes Quads(MeV) (MeV) (MW) (m)
Source, LEBT - 0.045 - - - - - 1
RFQ 0.045 3 1 0.5 1 - - 2.4Chopper line 3 3 3 0.06 - 3 6 3.6
DTL 7 120 13 11.8 15 - 160 64 120 236 42 1.5 - 42 28 101 236 383 32 1.9 - 32 16 80 383 1111 52 9.5 13 - 26 166 1111 2235 76 14.6 19 - 19 237Debunching 2235 2235 4 - 1 - 2 13
Total 223 39.9 49 77 257 668
Section
55 cryostats, 33 from LEP, 22 using components(68 total available)
49 klystrons (44 used in LEP)
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Superconducting cavities in the Superconducting cavities in the LEP tunnelLEP tunnel
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Roadmap (1)Roadmap (1)
1) 3 MeV pre-injector1) 3 MeV pre-injector 2006 at CERN2006 at CERNOn-going collaboration with CEA (Saclay-F) and CNRS (Orsay-F) to build, test and
install at CERN a 3 MeV pre-injector based on the “IPHI” RFQ (Injecteur de Protons de Haute Intensité)
E C R S IL H I sou rcean d L E B T
R F Q H E B T w ithB e a m D ia g n o stic s
sp ectrom eter
B e a mStopper
B ea m P o w er : 3 0 0 k W
9 5 K e V
2 R F S y s te m s3 5 2 M H z - 1 .3 M W
3 M e V
1 0 0 K VH V p la tform
8,6 m 6 m 14 m
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Roadmap (2)Roadmap (2)
2) Linac 4 in the South Hall of the CERN PS2) Linac 4 in the South Hall of the CERN PS
E.U. support for R. & D. on crucial componentsis being requested in the frame of a Joint Research Activity on “High Intensity Pulsed Proton Injectors” (HIPPI).
Goal: improved performance of the proton beam for the approved physics programme (LHC, CNGS, ISOLDE, AD,…) at a minimal cost
Principles: normal conducting linac (120 – 160 MeV / H-) which can later serve as the low energy part of the
SPLreplace (and improve upon) the present linac 2 (50 MeV / protons) as the proton source at CERNminimise cost by re-using buildings and LEP RF equipment
Main characteristicsMain characteristics
Energy: originally 120 MeV. Now increased to 160 MeV for the needs of the PSB (= factor 2 in 2 )
Intensity goal: 5x1013 in the PSB (CNGS, ultimate LHC in one PSB pulse)Emittance: 0.4 mm mrad (rms, norm.) – (3 times smaller)
17R.G. – 17/03/2003 MORIOND Workshop 2003
Linac4 layoutLinac4 layout
H-
RFQ RFQ1 chop. RFQ2DTL CCDTL
95 keV 3 MeV 120 MeV 150 MeV
40MeV 6 m 64 m
chopping
4 m
SCL/SC
Basic layout:120 MeV, 80 m, 16 LEP klystrons
Costing exercise still in progress (finished in fall?)First estimates at 60 MCHF
source
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Linac4 parametersLinac4 parameters
PARAMETERS Phase 1 (PSB)
Phase 2 (SPL)
Maximum repetition rate 2 50 Hz
Source current * 50 30 mA
RFQ current * 40 21 mA
Chopper beam-on factor 75 62 %
Current after chopper * 30 13 mA
Pulse length (max.) 0.5 2.8 ms
Average current 15 1820 A
Max. beam duty cycle 0.1 14 %
Max. number of particles per pulse 0.9 2.3 · 1014
Transverse norm. emittance (rms) 0.25 0.25 mm mrad
Longitudinal emittance (rms) 0.3 0.3 deg MeV
Maximum design current 30 A
Note: Linac4 is designed to be the first part of a future SPL for 14% duty cycle & very low loss
19R.G. – 17/03/2003 MORIOND Workshop 2003
Linac4 layout in South HallLinac4 layout in South Hall
"NEW LINAC" Layout in the PS South Hall - version 5.2.2002
12.0
m
PS Access
RF Workshop
Loading Area
Storage AreaRFQ Test stand352 MHz Test StandLoading
Area
to inflector & PSB
20R.G. – 17/03/2003 MORIOND Workshop 2003
Linac4 R&D (low energy part of SPL)Linac4 R&D (low energy part of SPL)
H-
RFQ RFQ1 chop. RFQ2DTL CCDTL
95 keV 3 MeV 120 MeV 150 MeV
40MeV 6 m 64 m
chopping
4 m
SCL/SC
H- source, 25 mA14% duty
Collaboration with IPHI (CEA-IN2P3), building an RFQ that will come to CERN in 2006
Design and construction of a chopping line to be tested with beam in 2006:
- chopper structure- chopper pulser- 3 bunching cavities
Construction of a hot model of CCDTL (Cell-Coupled Drift Tube Linac
Chopper prototype
CCDTL prototype
(chopping=removing at low energy the linac bunches that would fall outside of the PSB bucket)
21R.G. – 17/03/2003 MORIOND Workshop 2003
An example of R&D: the CCDTLAn example of R&D: the CCDTL
CCDTL = Cell Coupled Drift Tube Linac, a simpler and cheaper alternative to DTL for energy > 40 MeV
quadrupolecoupling cell
DTL-like accelerating cell(2 or 3 drift tubes)
CCDTL prototype
22R.G. – 17/03/2003 MORIOND Workshop 2003
Roadmap (3)Roadmap (3)
3) Full performance / high power proton injector / driver3) Full performance / high power proton injector / driver
Preliminary step: Design optimisation / successful hardware prototyping
Next steps: Positive decision for a physics programme needing such a driver Attribution of resources for machines, targets and experiments Authorisation of construction (INB procedure etc.)
23R.G. – 17/03/2003 MORIOND Workshop 2003
H-
RFQ RFQ1 chop. RFQ2 RFQ1 chop. RFQ2 0.52 0.7 0.8 dump
Source Low Energy section DTL Superconducting section
45 keV 3 MeV 120 MeV 2.2 GeV
40MeV 237MeV
6 m 64 m 584 m
PS / Isolde
Stretching andcollimation line
Accumulator Ring
Debunching
383MeV
668 m
DTL CCDTLchopping
H- source, 25 mA14% duty cycle
Fast chopper
(2 ns transition time)
Normal conducting (NC) cavities
Superconducting (SC) cavities: =0.52, 0.7, 0.8
Beam dynamics studies aiming at minimising losses (activation!)
Vibrations of SC cavities: analysis, compensation schemes.
RF system: 352 MHz (LEP klystrons)
SPL R&D (high energy part)SPL R&D (high energy part)
24R.G. – 17/03/2003 MORIOND Workshop 2003
R&D topics – low R&D topics – low SC cavities SC cavities
The =0.7 4-cell prototype
CERN technique of Nb/Cu sputtering excellent thermal and mechanical stability
(important for pulsed systems) lower material cost, large apertures, released
tolerances, 4.5 K operation with Q = 109
Bulk Nb or mixed technique for =0.52 (one 100 kW tetrode per cavity)
(E. Chiaveri, R. Losito)
25R.G. – 17/03/2003 MORIOND Workshop 2003
R&D topics - vibrationsR&D topics - vibrations
Effect on field regulation
Effect onthe beam
vector sum feedback can compensate only for vibration amplitudes below 40 Hz
possible remedies: piezos and/or high power phase and amplitude modulators
(prototype ordered - H. Frischholz)
+ possible chaotic effects(J. Tückmantel)
26R.G. – 17/03/2003 MORIOND Workshop 2003
R&D topics – loss managementR&D topics – loss management
For hands-on maintenance, the generally accepted figure is a particle loss < 1 W/m
For the SPL, 10 nA/m (10-6/m) @ 100 MeV, 0.5 nA/m (10-7/m) @ 2 GeV
Present Linac2 loss level (transfer line): 25W/80m = 0.3 W/m (but hot spots at > 1 W/m !)
Mechanism of beam loss in the SPL: 1. H- stripping < 0.01 W/m in quads for an off-axis beam 2. Residual gas < 0.03 W/m @ 10-8 mbar, 2 GeV (but 0.25 W/m @ 10-7)
3. Halo scraping more delicate, requires: large apertures (SC is good!) careful beam dynamics design
27R.G. – 17/03/2003 MORIOND Workshop 2003
SummarySummary
At CERN:At CERN:
High intensity protons beams will remain a strong asset High intensity protons beams will remain a strong asset beyond 2010. Improving their performance is a logical and beyond 2010. Improving their performance is a logical and necessary path for the approved physics programme.necessary path for the approved physics programme.
The SPL would be a high potential upgrade, preparing for the The SPL would be a high potential upgrade, preparing for the addition of new physics goals.addition of new physics goals.
28R.G. – 17/03/2003 MORIOND Workshop 2003
Conclusion / RecommendationConclusion / Recommendation
A large effort in R. & D. is required, with very similar A large effort in R. & D. is required, with very similar goals and technologies than for EURISOLgoals and technologies than for EURISOL
Close coordination between teams is absolutely Close coordination between teams is absolutely necessary to share the effort and present a necessary to share the effort and present a
coherent set of requests to the E.U..coherent set of requests to the E.U..