drift tube linac andrea pisent infn italy april 21, 2015
TRANSCRIPT
Drift Tube Linac
Andrea PisentINFN Italy
www.europeanspallationsource.seApril 21, 2015
Overview
• DTL design• Production critical steps• Critical interfaces
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Schedule
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Technical performances (SoW)
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• The DTL (Drift Tube Linac) cavity is constituted of 20 modules, assembled in 5 tanks, composed of 4modules each, for a total length of approximately 40 m.
• This profile describes the life cycle phases of the DTL regardless of the responsibilities assigned to contributors of this Scope of Works.
1. DTL design2. Manufacturing and test of components 3. Assembly, low power test and tuning of each tank. 4. Transport and Installation in the ESS tunnel in Lund5. Check out and RF conditioning to full power6. Beam commissioning in two steps, beam dump after
tank 1 and tank 57. Operation with the other Accelerator components (and
neutron production target). • This scope of work describes the points from 1. to 6. CERN-INFN prototype
First tank
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DTL Input Constraints (after the design update in 2013)
Lund - 2014_12_02 Audit
Requirement Target value CommentParticle type H+ H- are possible
Input energy 3.62 MeV +- 50 keVOutput energy 90 MeV
Input current 62.5 mA Peak, (2.86 ms long with a repetition rate of 14 Hz)
Input emittance 0.28 mm mrad Transverse RMS normalized 0.15 deg MeV Longitudinal RMSEmittance increase in the DTL <10% DesignBeam losses <1 W/m Above 30 MeVRF frequency 352.21 MHz Duty cycle <6% Peak surface field <29 MV/m 1.6 EkpRF power per tank <2.2 MW Peak, dissipated+beam load, including Module length <2 m Design constraintFocusing structure FODO Empty tubes for Electro Magnetic Dipoles
(EMDs) and Beam Position Monitors (BPMs) to implement beam corrective schemes
PMQ field <62 T/m
Beam dynamics
Lund - 2014_12_02 Audit
∆ 𝜀𝑥 ,𝑦=2% ,∆𝜀𝑧=1%Uniform input distribution
Max Gradient ~61.6 T/m FODO lattice
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DTL design
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Tank 1 2 3 4 5
Cells 61 34 29 26 23
E0 [MV/m] 3.00 3.16 3.07 3.04 3.13
Emax/Ek 1.55 1.55 1.55 1.55 1.55
φs [deg] -35,-25.5 -25.5 -25.5 -25.5 -25.5
LTank [m] 7.62 7.09 7.58 7.85 7.69
RBore [mm] 10 11 11 12 12
LPMQ [mm] 50 80 80 80 80
Tun. Range [MHz] ±0.5 ±0.5 ±0.5 ±0.5 ±0.5
Q0/1.25 42512 44455 44344 43894 43415
Optimum β 2.01 2.03 2.01 1.91 1.84
Beam Det [kHz] +2.3 +2.0 +2.0 +1.8 +1.8
Pcu [kW] (no margin) 870 862 872 901 952
Eout [MeV] 21.29 39.11 56.81 73.83 89.91
PTOT [kW] 2192 2191 2196 2189 2195
DTL Selected technologies
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• DTL normal conducting, PMQ focusing, internal BPM and steering dipoles for orbit correction, space for additional beam instrumentation in the tank transitions.
• With this architecture the beam dynamics is very smooth, with short focusing period, to fulfill the emittance increase requirement.
• The mechanical stiffness and geometrical accuracy is guaranteed by the thick stainless steel tank, and by the DT positioning system (CERN patent).
• Key mechanical technologies• High precision machining• qualification of small parts, (DT) by CMM and large pieces (tank) (laser tracker, arm..)• E-beam welding (Zanon, CERN….)• Vacuum brazing (in house)• Copper-plating of large tanks (two possible providers, CERN and GSI)
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CMM machine at INFN Padova
Mechanical Design
Lund - 2014_12_02 Audit
TANK (304L stainless steel)internal Cu plating on finished surface internal Cu plating on finished surface (Ra 0,8) high stiffness support MASTER
GIRDER (EN AW5083 Al alloy)Precise positioning of the DT stem axis in steel bushing SLAVE
HelicoflexVacuum tightness at stem/tank interface
Rough sleeve316LN
Sep. cylinder304L
Rough DT bodyCuC2-OFE
Brazed joint
Beam pipe
Steerer (cables not represented)
DTL sub-systems and interfaces
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DTL
• Pumps• Valves• gauges
RF network
• RF couplers• RF pick ups• Movable tuners and
controllers (TCP/IP prot.)
Control system
• Water cooling skid• Water cooling
distribution
• Local Control system (vacuum, cooling)
• Steerer Power Supply
• Support• Alignment refs
INFN
COOLING SYSTEM
Spoke section
MEBT
RF window
Heat exchanger
Valve
RF SYSTEM
Vacuum SYSTEM
Diagnostic
• Intertanks• BPM signals• BCT inside DTL end
flange
Valve
Interfaces
Lund - 2014_12_02 Audit
1 Cooling skid with 5 three-ways valves
Vacumm manifold
Pick-up and movable tuners
RF windows and supports
Intertanks and tank covers
Prototypes and high power test (planning and results)
Lund - 2014_12_02 Audit
PMQ
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Rare earth block specifications (Sm2Co17):- Error Br < 3%- Error an Angle < 2deg- Dimension tolerances < 0.05mm – 0.1mm- Br=1.1 T → Simulated Gradient=65 T/m
Assembly specifications:- Housing Material - Stainless Steel (316LN)- Outgassing rate per magnet below 4.10-6mbar l s-1- Gradient integral error (rms) -+ 0.5 %- Magnetic versus geometric axis: < 0.1 mm- Harmonic content at 10 mm radius: Bn/B2 for
n=3,4,...10: < 0.01- Roll: 1 mrad
Goal:- define assembly criticalities- verify feasibility of specifications - define magnetic measurement bench and procedure- tunability of PMQ- Company qualification
0
0.2
0.4
0.6
0.8
1
1.2
0
0.01
0.02
0.03
0.04
0.05
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
B [T
]
radi
al c
oord
.[m
]
z [m]
drift tubePMQB(z) at (x,y)=(12,12)mmB(z) at (x,y)=(1,1)mmB(z) at (x,y)=(5,5)mmB(z) at (x,y)=(10,10)mm
( )
0.046( )
lineeffective
MAX
B z dz
L mB line
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PMQ
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Rare earth block specifications (Sm2Co17):- Error Br < 3%- Error an Angle < 2deg- Dimension tolerances < 0.05mm – 0.1mm- Br=1.1 T → Simulated Gradient=65 T/m
Assembly specifications:- Housing Material - Stainless Steel (316LN)- Outgassing rate per magnet below 4.10-6mbar l s-1- Gradient integral error (rms) -+ 0.5 %- Magnetic versus geometric axis: < 0.1 mm- Harmonic content at 10 mm radius: Bn/B2 for
n=3,4,...10: < 0.01- Roll: 1 mrad
Goal:- define assembly criticalities- verify feasibility of specifications - define magnetic measurement bench and procedure- tunability of PMQ- Company qualification
0
0.2
0.4
0.6
0.8
1
1.2
0
0.01
0.02
0.03
0.04
0.05
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
B [T
]
radi
al c
oord
.[m
]
z [m]
drift tubePMQB(z) at (x,y)=(12,12)mmB(z) at (x,y)=(1,1)mmB(z) at (x,y)=(5,5)mmB(z) at (x,y)=(10,10)mm
( )
0.046( )
lineeffective
MAX
B z dz
L mB line
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Prototypes: PMQ
Vacuum test- final pressure similar to the
background value. - Larger amount of H2O, H2, O2, C02
These cannot be determined if they are from the AISI frame or from the PMs.
1.00E-12
1.00E-11
1.00E-10
1.00E-09
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
0 2 4 6 8 10 12 14 16 18 20
Parti
al P
ress
ure
[mba
r]
Time [hr]
Hydrogen
Helium
Water
Nitrogen
Oxygen
Argon
Carbon Dioxide
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Prototypes: PMQ
The PMQ prototype built and assembled at INFN-Torino has been measured with a rotating coil at CERN
The integrated gradient is 63.7 T/m and the harmonic content is lower than 1% at 7.5 mm radius
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Prototypes: BPM and EBW test
• BPM: strip-line already brazed, waiting for coaxial feed-trough from USA• Mapper at LNL
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Result of brazing and e beam welding test
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• EBW on Brazing possible weak point (T ebw > 1100°C, Tbrazing =850 °C)
• Simulation shows non problem (Power_EBW=1800 W, v=12mm/s, spot volume=1mm3, brazed point < 650°C)
• Tests have proven vacuum tightness and integrity (EDM slice)
brazing
ebw
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High Power test @ LNL• 2 solid state amplifiers 125 kW-CW each, 352 MHz.• Control system developed for multiple coupler feeding.• Waveguides and circulator at LNL.• IFMIF high power test stand now ready will be readapted.• High power DTL prototype from Linac4-CERN (peak power 180 kW, 10% duty cycle,
E0=3.3MV/m) agreement KN2155/KT/BE/160L between CERN and INFN-LNL• 3 drift tubes will be replaced by ESS drift tubes containing instrumentation + 1movable tuner
for frequency control.• Ready for test in summer 2015 (delay of 6 moths due to amplifier delivery)
Magic tee
Prototype schedule
Deliverable no. Deliverables Delivery Deadline
1 Design, purchasing and installation of BPM test stand at INFN-LNL. 30/10/2014
2 Prototype production of a permanent magnet quadrupole (PMQ). Complete characterization of PMQ at CERN test bench. 30/11/2014
3 Prototype production of a BPM and Steerer to be installed in proper DTs. 30/03/2015
3Construction and assembly of three complete DT prototypes with PMQ, with BPM and with steerer. Installation of DT prototypes in Linac4 DTL prototype.
30/05/2015
4 Design and construction of a movable tuner. 31/03/2015
5 Modification of the test stand used for IFMIF in order to test ESS components. 30/05/2015
6 Tests of DT and tuner at nominal power and duty cycle (the DTL prototype developed by CERN and INFN-LNL will be used). 31/06/2015
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Production sequence (TBC by CDR)
1. Forged cylinders production, tank machining, copper plating. Girder and other components, CMM and vacuum tests…
2. Production of the beam components (PMQ, BPM, dipole steerers)3. Production of vacuum, support and inter-tank components4. DT Brazed structure production (with cooling circuit tested)5. Integration of the beam component in the DT6. E-beam welding sealing, final tests on DTs 7. Assembly of the module (2 m), installation and alignment of the DTs8. Assembly of the tank (4 modules), alignment, machining of the adaptation rings for
relative position, tuning, tuners, ports, vacuum test,…9. Installation and alignment of the tanks in the tunnel, installation of the intertank
plates10. Installation of vacuum, cooling, RF couplers….NOTE 1-6 al INFN site, 7-8 DTL workshop at Lund, 9-10 in the tunnel
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SITE REQUIREMENTS FOR DTLW
• The DLTW is a "clean" and quite environment, temperature controlled (+1 deg over 30 min for bead pulling, +4 deg over the year).
• About 13x 10 m is necessary for the assembly of the tank, separate space will be used for possible storing of assembled tanks.
• The DTLW should be a closed part of a larger building, or in any case there should be a convenient entry space (for structures) before exiting outdoor (at least 10x8 m); such space can be shared with other labs; it is useful sometimes the possibility to enter this space with small vans or tracks. A small vestibule for people (about 2x2 m) is required.
• A slow crane at least 3 tons inside the workshop for the assembly of the tank is needed.
• The DTLW should be not far from the tunnel, a strategy to move the 8 tons tank into the tunnel will be defined by ESS.
• Mechanical workshop for small interventions and adjustments should be accessible, electrical supply and compressed should be available.
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Preliminary Schedule
• 2014: conceptual design• Q1 2015: completion of critical prototyping phase• April 2015 Integration on site meeting• June 2015 CDR• 2015: technical design phase, detailed drawings, tender for rough
material• 2016-2017: construction (sequence: tank 5-4-3-1-2)• 2017-2019: assembly and tuning (sequence: tank 5-4-3-1-2)• 2017-2018:
– installation and conditioning in the tunnel of tank 5-4-3. – Installation conditioning and beam commissioning of tank 1 in the tunnel– Installation and conditioning of tank 2– beam commissioning of the 5 DTLs
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DTL organization at partner lab
• Andrea Pisent (WU coordinator, LNL)• Francesco Grespan (deputy
coordinator, LNL)• Paolo Mereu (Mechanics design,
Torino)• Michele Comunian (Beam dynamics,
LNL)• Carlo Roncolato (Vacuum system and
brazing, LNL)• Marco Poggi (Beam instrumentation,
LNL)• Mauro Giacchini (Local Control System,
LNL, TBD)
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Torino
LNL
Bologna
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Major Procurements
• Tank forged material (stainless steel)• OFE Copper parts• Stainless steel parts• RF windows• Movable tuners• Vacuum valves• Intertank boxes• Copper plating• Tank machining• Drift Tubes machining• E-beam welding• BPM production• Steerer dipoles (design, production)• PMQ (material, machining, field test)• Supports• Cooling skid and cooling circuit components
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Top risks
• Beam performances in beam commissioning (61 tubes in tank 1 and final).
• DT alignment.• DT production (QA, mainly dimensions,
vacuum and water tightness).• Copper plating quality• Intertank integration• Logistics: assembly of the tank in the DTW,
transport to the tunnel…..• RF conditioning
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Next Six Months
• CDR• Completion of mechanical specs and production
drawings• Completion of critical prototypes• Forged tank procurement for the 1st module • Launch the RF window procurement
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Summary
• The DTL is a large and complex part of the ESS linac. Respect to the successful Linac4 DTL @ CERN we shall have higher energy and duty cycle.
• The overall linac performances are crucially determined by the quality of the DTL realization.
• The DTL design has been optimized for best beam performances, the main technological choices are been tested with prototypes.
• In June we shall have the CDR, necessary to launch the first procurements.
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