drift tube linac andrea pisent infn italy april 21, 2015

Drift Tube Linac

Andrea PisentINFN Italy

www.europeanspallationsource.seApril 21, 2015

Overview

• DTL design• Production critical steps• Critical interfaces

2 Istituto Nazionale di Fisica Nucleare (Italy)

Schedule


Technical performances (SoW)

4

• 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

Istituto Nazionale di Fisica Nucleare (Italy)

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


DTL design

7

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

8

• 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)


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

10

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

13

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


PMQ

14

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


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


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


Prototypes: BPM and EBW test

• BPM: strip-line already brazed, waiting for coaxial feed-trough from USA• Mapper at LNL


Result of brazing and e beam welding test

18

• 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


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


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


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.


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


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)

24

Torino

LNL

Bologna


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


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


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


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.


drift tube linac andrea pisent infn italy april 21, 2015

Documents

high power dtl prototype

test of components

low power test

ifmif high power test

linac4 dtl prototype

cerninfn prototype

prototype production

fisica nucleare italy