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Linac4 Status M. Vretenar for the

Linac4 team

BI Review 18.10.2011

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Linac4 motivationsNew 160 MeV H- linear accelerator to replace Linac2 as injector to the PS Booster.

Project approved in June 2007, started on January 1st, 2008.

MOTIVATIONS:1. Make possible an upgrade of the LHC luminosity

beyond nominal, by reducing space charge at PSB injection (factor 2 in bg2 and brightness going from 50 to 160 MeV).

2. More modern and sustainable than Linac2 (worries for long-term operation of Linac2 ).

3. Flexible operation and reduced loss with new technologies (chopping, H- injection).

4. Higher intensity for non-LHC users.5. Prepare for a possible high-intensity upgrade

(neutrino facility).

Present LHC injection chain:Linac2 (50 MeV)↓PS Booster (1.4 GeV)↓PS (25 GeV)↓SPS (450 GeV)↓LHC

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Linac4 on the CERN site

Linac4 excavation works, May 2009 (aerial photo)

About 100m in length, built on one of the last “free” areas on the CERN Meyrin site, providing easy connection to the PSB and the option of a future extension to higher energy and intensity (SPL, 4 GeV) for a n physics programme.

Linac tunnel 12 m underground, surface building for RF and other equipment, access module at low energy.

Construction works started in October 2008, completed in October 2010 (2 years). 3.25 years from project approval to delivery of the building.

Linac4

Linac4 tunnel

Linac4-Linac2 transfer line

Equipment building

Access building

Low-energy injector

ground level

Linac2

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“Mount-Citron”, September 2008

Building construction – 2008/10

Excavation work, April 2009

Surface building, August 2010

Under the PSB technical gallery, May 2009

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Linac4 Infrastructure

Installation of infrastructure is progressing in building and tunnel- Electrical distribution, cable trays, piping- Waveguides- Faraday cage for electronics- False floor

Next steps:Cabling campaignsInfrastructure completed by June 2012

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Linac4 Beam Parameters

Ion species H−

Output Energy 160 MeVBunch Frequency 352.2 MHzMax. Rep. Frequency 2 HzMax. Beam Pulse Length 0.4 msMax. Beam Duty Cycle 0.08 %Chopper Beam-on Factor 65 %Chopping scheme: 222 transmitted /133 empty bucketsSource current 80 mARFQ output current 70 mALinac pulse current 40 mATr. emittance (source) 0.25 p mm mradTr. emittance (linac exit) 0.4 p mm mrad

Max. repetition frequency for accelerating structures 50 Hz

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- Accelerating structures and klystrons designed for 50 Hz. - Cooling, power supplies and electronics only for 2 Hz.

1.1 Hz maximum required by PSB

Chopping at low energy to reduce beam loss at PSB.

Factor 2 in bg2 w.r.t. Linac2

Frequency of LEP (ideal for a linac), some klystrons and RF equipment still available

Current and pulse length to provide >twice present intensity in PSB.

H¯ for the first time at CERN!

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Linac4 layout

RFQchopper lineDTLCCDTLPIMS

160 MeV 104 MeV 50 MeV 3 MeV86 m

Normal-conducting linear accelerator, made of:1. Pre-injector (source, magnetic LEBT, 3 MeV RFQ, chopper line)2. Three types of accelerating structures, all at 352 MHz (standardization of components).3. Beam dump at linac end, switching magnet towards transfer line to PSB.

No superconductivity (not economically justified in this range of b and duty cycles);

Single RF frequency 352 MHz (no sections at 704 MHz, standardised RF allows considerable cost savings) ;

High efficiency, high reliability, flexible operation → 3 types of accelerating structures, combination of PMQ and EMQ focusing.

Energy [MeV]

Length[m]

RF Power[MW]

Focusing

RFQ 0.045 - 3 3 0.6 RFDTL 3 - 50 19 5 112 PMQsCCDTL

50 - 102 25 7 14 PMQs, 7 EMQs

PIMS 102 - 160

22 6 12 EMQs

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Linac4 – The challenges

Low-energy section: ion source, RFQ, choppinggeneration of low-emittance intense H- beams, transport and emittance preservation through LEBT and RFQ, efficient transport and chopping

Accelerating structuresdesign prototyping and construction of reliable high efficiency RF structures

Linac beam dynamicsemittance preservation, low loss design for possible high-duty operation

PSB injection 4-ring stripping, beam optics

Reliabilitybenchmark: present availability of Linac2 is 98.5%!

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Linac4 – Low energy test stand

Ion source and LEBT completed and under test;

RFQ in construction; Chopping line

completed, tested without beam;

LEP klystron and modulator installed and tested.

Complete beam diagnostics line being assembled.

Beam tests with RFQ from beginning 2012

klystronmodulator

sourceRFQchopper line

diagnostics line

3 MeV TEST STAND for early characterization of low-energy section; will be moved to Linac4 in 2013

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Problems with the H- source

2005: decision to build an RF Volume source based on the DESY design: - no resources for an internal development;- DESY source had high reliability (external antenna, Cesium-free);- higher extraction voltage + improvements to RF generator and matching to achieve

higher current: 45 kV, 100 kW for 80 mA (DESY: 35 kV, 30 kW, 30 mA). June 2009: source started in the “3 MeV test stand”. Extensive measurements at 35 kV. From May 2010: increase extraction to 45 kV but severe sparking forbids operation.

Reason: intense electron beam co-extracted with the H- melts the e¯ dump (up to >200 kW instantaneous power in e- beam!). Vaporization (and destruction) of the dump induces sparking.

DESY had less electrons (with less voltage) and more H-. A “chemical” reason?

extraction electrode

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Revised source program

1. Extend and improve the source test stand in Bld. 352 (ex-SPL source test stand). 2. Build quickly an improved version of the DESY RF source for L4 commissioning.3. Build and optimize a Cesiated RF source for L4 2nd part of commissioning and operation.4. Study (and build) a magnetron-type source to go to high currents – if needed.

2 test stands,

B.357: ion source (+LEBT, diagnostics)

B.152: RFQ and chopper testing

?

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The Linac4 RFQEnergy 3 MeV, length 3m, 3 section of 1 m each.

Brazed 4-vane design with simplified shape and cooling, for max. duty cycle 10%.

Construction entirely done at CERN: machining, metrology, brazing (horizontal). CEA (F) contribution for RF design and measurements.

Status: Modules #1 and #2 completed, Module #3 ready for 2nd and last brazing.

Programme: RF tests October 2011, conditioning November/December 2011, first beam end 2011.module #3

module #1

“chopping”: removing microbunches (150/352) to adapt the 352MHz linac bunches to the 1 MHz booster frequency

Match from the RFQ

Match to the DTLChop

0.12

0.125

0.13

0.135

0.14

0.145

0.15

0.155

0.16

2.00E-07

2.50E-07

3.00E-07

3.50E-07

4.00E-07

0 0.5 1 1.5 2 2.5 3 3.5 4

deg M

eV

pi m

m m

rad

meters

100% (of the beam) - rms emittances vs lenght

x y z

Emittance increase 20-30%

Chopping

beam

dump

Chopper line layoutLength 3.6 m

Already completed, installed in the test stand and tested without beam.

Chopper: 2 meander-line structures on ceramic substrate.

2.84 ns

PSB injection scheme (with energy ramping)

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Linac4 – Drift Tube Linac

● 3-50 MeV, 3 tanks.● New CERN design, tested on a prototype (1m, 12 drift

tubes) at full RF power (10% duty cycle).● Main features: drift tubes rigidly mounted on a girder,

with special mounting mechanism, only metallic joints and no adjustment. Tank in Cu-plated stainless steel. Permanent Magnet Quadrupoles in vacuum.

● Construction started (DTs with ESS-Bilbao).● Tank1 ready for tests at beginning 2012.

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Linac4 – Cell-coupled DTL

● 50-100 MeV, 7 modules of 3 tanks each.● New design, tested on a prototype (2 tanks, 4 drift

tubes) at full RF power (10% duty cycle).● Main features: Focusing by PMQs (2/3) and EMQs

(1/3) external to drift tubes. Short tanks with 2 drift tubes connected by coupling cells.

● Construction started at VNIITF (Snezinsk) and BINP (Novosibirsk) in January 2010.

● Module#1 and #2 completed, under low-power tests at BINP. To be delivered to CERN for testing end 2011.

Structure used for the first time in a particle accelerator !

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Linac4 – Pi-Mode Structure

● 100-160 MeV, 12 tanks of 7 cells each.● Tank #1 (pre-series) completed and RF conditioned

to 1.25 times the design voltage. ● Main features: Focusing by external EMQs, tanks of

7 cells in pi-mode. Full-Cu elements, EB-welded.● Construction started (2011) in collaboration with

Soltan Institute (Warsaw) and FZ Julich.

Structure used for the first time in a proton accelerator !

Posters TUPS100 - MOPC055

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Linac4 – External Contributions

H-source RFQ DTL

45 keV 3 MeV 50 MeV 100 MeV 160 MeV

chopper line CCDTL PIMS transfer line to PSBLEBT

80 m

Chopper line built in a EU Joint Research Activity.

Participation of ESS-Bilbao in DTL construction.

Construction of CCDTL in Russia, via an ISTC Project.

Collaboration agreement with Soltan Institute (Poland) for PIMS construction.

Prototype modulator, waveguide couplers, alignment jacks from India.

RFQ RF design, RF amplifiers, modulator construction (French Special Contribution).

Network of agreements to support Linac4 construction. Relatively small fraction of the overall budget, but access to specialized manpower and share of information with other teams. Integration at the component level.

Movable tuners and DTL prototype from Italy.

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Requirements for Linac4 current

MAIN LINAC4 USERS

PSB out (ppp)

PSB in (ppp)

Linac4 current in 400ms(mA)

Linac4 current in 160ms(mA)

Linac4 current in 80ms(mA)

LHC present 0.7x1013 0.9x1013

(3.6) 9 18

ISOLDE present

3.5x1013 4.5x1013

18 - -

LHC final 1.4x1013 1.8x1013

(7.2) 18 36

ISOLDE final

7.0x1013 9.0x1013

36 - -

with 20% margin for beam loss

40 turns / PSB ring

20 turns / PSB ring

1. Linac4 design 400 ms pulse and 40 mA current correspond to 1014 ppp (twice present ISOLDE with some additional margin).

2. After connection of Linac4 to the PSB, Linac4+PSB is required to provide the present nominal beams. It is expected to reach the goal for LHC 1-2 years after connection; there are no clear commitments to ISOLDE.

3. In order to gain some more margin, the maximum Linac4 pulse has been recently extended to 600 ms.

With linac current 20 mA → present beams in PSB + full intensity LHC beam with 40 turns injection.

With linac current 40 mA → maximum ISOLDE beam + full intensity LHC beam with 20 turns injection.

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Requirements for Linac4 emittance

• Design transverse emittance from ion source 0.25 p mm mrad (rms)

• Design transverse emittance at PSB

input 0.4 p mm mrad (rms)

We risk to need compromising between current and emittance…

2.00E-07

2.50E-07

3.00E-07

3.50E-07

4.00E-07

4.50E-07

0 10 20 30 40 50 60 70 80

100% Normalised RMS transverse emittance (PI m rad)

x

y

transition

transition

Maximum acceptances (no errors, zero current)

RFQ : 0.55 p mm mradChopper : 0.4 p mm mrad DTL : 0.8 p mm mrad(comparable for other accelerating structures, larger for the transfer line)The PSB can accept a somehow larger emittance

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Linac4 – schedule

Building delivery

2011:Infrastructure installation

2012/13:Accelerat

or installatio

n

2013/14:Commissio

ning

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Linac4 commissioning schedule

ID Task Name

1 Linac 4 - Machine2 L4L (3 MeV)3 End of Test Stand operation4 source H- installation5 LEBT installation6 RFQ installation7 MEBT installation8 Hardware Test9 Beam commissioning - 3 MeV10 L4D (50 MeV)11 DTL tanks 3 installation12 DTL tank 1 installation13 Hardware Test14 Beam commissioning15 DTL tanks 2 installation16 intertanks 1-2 & 2-3 installation17 Hardware Test18 Beam commissioning - 50 MeV19 L4C (102MeV)20 CCDTL 3-7 installation21 CCDTL 1-2 installation22 Hardware Test23 Beam commissioning - 102 MeV24 L4P (160 MeV)25 PIMS 4-12 installation26 PIMS 1-3 installation27 Hardware Test28 L4Z29 Main dump30 MQF installation31 BI installation (BTVx3, BCT)32 Beam commissioning Linac4 - 160 MeV

Linac 4 - Machine L4L (3 MeV)

End of Test Stand operationsource H- installation

LEBT installationRFQ installation

MEBT installationHardware Test

Beam commissioning - 3 MeVL4D (50 MeV)

DTL tanks 3 installationDTL tank 1 installation

Hardware TestBeam commissioning

DTL tanks 2 installationintertanks 1-2 & 2-3 installation

Hardware TestBeam commissioning - 50 MeV

L4C (102MeV)CCDTL 3-7 installation

CCDTL 1-2 installationHardware Test

Beam commissioning - 102 MeVL4P (160 MeV)

PIMS 4-12 installationPIMS 1-3 installation

Hardware TestL4ZL4ZMain dumpMQF installationBI installation (BTVx3, BCT)

Beam commissioning Linac4 - 160 MeV

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 4142 4344 4546 474849 50 5152 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19December 2012January 2013February 2013March 2013 April 2013 May 2013 June 2013 July 2013 August 2013September 2013October 2013November 2013December 2013January 2014February 2014March 2014 April 2014 May 2014

2012 2013 2014

Start of beam commissioning (3MeV): May 2013 End of beam commissioning (160 MeV): April 2014

(version November 2010)

5 commissioning stages: (on intermediate dumps) 3 MeV 10 MeV 50 MeV 100 MeV 160 MeV

Connection to the PSB during a long (min. 7 months) LHC shut down after 2014.

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Thank you for your attention