Proton Linac, PBAR@FAIR Workshop, December 3 rd - 4 th, 2007 The FAIR Proton Linac Outline...

Proton Linac, PBAR@FAIR Workshop, December 3rd - 4th, 2007

The FAIR Proton Linac

Outline

• Requirements to Proton Linac

• Source, RFQ, DTL, RF

• Beam Dynamics

• Civil Construction


p-bar target

p-linac

Super- FRS

SIS100SIS300

HESR

CR

RESR

The FAIR Accelerator ComplexSIS 100

NESR

HESR Antiproton Prod. Target

SIS18

CR

GSI Today

RESR

p-linac SIS 300

UNILAC

FAIR

100 m

FAIR: Facility for Antiproton and Ion Research

71010 cooled pbar / hour


<=100 x :4 x :

Injection of protons into SIS18Acceleration to 2 GeVInjection into SIS100

Acceleration to 29 GeVImpact on target hot pbars

Stoch. pbar cooling in CRInjection into in RESR

Injection into HESRAcceleration to 14.5 GeV

or

Deceleration in NESR to 30 MeVExtraction to low energy pbar

experiments

Accelerator Chain for Cooled Antiprotons


• ηMTI → 60% (good empiric value)

Injection into Synchrotron SIS18

• The client of the p-linac is SIS18

• Number of protons that can be put into SIS18 limited to

, i.e. depends on energy

• Number of SIS18 turns during injection depends on phase space areas

acceptance of SIS18

single shot from p-linac( emittance ~ size2 ~ γ-

1 )

ηMTI := green area / red area = filling factor

SIS18

p-lin

ac

• Injection energy → duration → current → emittance ε are coupled

Energy remains to be chosen


Choice of Proton Linac Energy

0

10

20

30

40

50

60

70

80

90

100

10 60 110 160 210

Proton Linac Energy [MeV]

p-D

uty

SIS

100

[%],

Co

ole

d p

bar

R

ate

[10^

9/h

]

0

5

10

15

20

25

30S

IS1

8 S

pa

ce

Ch

arg

e L

imit [1

0^

12

]

SIS100 Duty Time

Cooled pbar / h

SIS18 SpaceCharge Limit

final rate of cooled pbar depends on injector energy:

70 MeV

→ 16.5 mA / µm →

• I = 35 mA

• βγεx = 2.1 µm

limited by stoch. cooling power


p-Linac Overview

• ECR proton source & LEBT

• RFQ

• 2 re-bunchers

• 2*6 accelerating cavities

• 5 MW of beam loading (peak), 710 W (average)

• 11 MW of total rf-power (peak), 1600 W (average)

• 2 dipoles, 45 quadrupoles, 7 steerers

• 10 turbo pumps, 34 ion pumps, 9 sector valves

• 41 beam diagnostic devices

Beam energyBeam current (op.)Beam current (des.)Beam pulse lengthRepetition rateRf-frequencyTot. hor emit (norm.)Tot. mom. spreadLinac length

70 MeV 35 mA 70 mA 36 µs 4 Hz325.224 MHz2.1 / 4.2 µm≤ ± 10-3

≈ 35 m

Diagnostic insertion

95 keV 3 MeV 70 MeV

Source LEBT RFQ CH-DTLRe-Buncher

to Dump

to SIS18


Partners and People

University of Frankfurt• Cavity design• RFQ design (4-rod)• Beam dynamics

CEA/Saclay• Proton source & LEBT

ITEP Moscow• RFQ design (4-vane)

GSI Darmstadt

Cavity design, Beam dyanamics/diagnostics, Magnets,

Power converters, Rf-sources, Proton source,

Diagnostics, UHV, Civil constr., Controls, Coordination

U.Ratzinger, A.Schempp, R.Tiede

R.Gobin et al.

G.Aberin-Wolters, R.Bär, W.Barth, G.Clemente, P.Forck, L.Groening, R.Hollinger, C.Mühle, H.Ramakers, H.Reich, W.Vinzenz, S.Yaramyshev

S.Mineav et al.


Proton Source & LEBT

Proton energy

95 keV

Proton current

100 mA

Max. rep. rate

4 Hz

βγεtot

(transv.)≤ 1.8 µm

High reliability

High stability

Requirements at LEBT exit:SILHI at CEA/Saclay: 95 keV, > 100 mA, dc

95 keV


Beam Measurements at CEA/Saclay

• Measured beam parameters meet ..the requirements to FAIR p-linac

• Stable source needed for production ..machine like p-linac

LEBT exit: two measurements using different electronics, separated by 4 days, intermediate opening of the plasma chamber:

optics for RFQ-injection

During 3 weeks of measurements :

• always reliable & stable 100 mA beam

• no single sparking of the HV

• no interruption due to any malfunction


Radio Frequency Quadrupole (RFQ)

3.5 m

4-rod (cheaper)

164

480

164

480

164164

480

4-vane (state of the art)

Two designs followed:

Both designs meet requirements

0.1 MeV 3.0 MeV+V +V

-V

-V~


Drift Tube Linac DTL

3.0 MeV 70 MeV

• DTL: wall plug power → em. (rf) fields (325 MHz) → proton beam power

• Creation of rf-power is project cost driver

• 64% of p-linac project cost related to rf-power


Rf-Power Source (Klystron)

TOSHIBA Klystron 3740A/GSI

• peak rf-power 3.0 MW

• no R&D related cost & risks

• first device ordered

• delivery in March 2008

• klystron: wall plug power → rf-field power

• industrial devices

• length ≈ 5 m

• weight ≈ 2.5 tons


0102030405060708090

100

0 20 40 60 80

Proton Energy [MeV]

rf-power → beam power

Accelerating Cavities

• Crossed-bar H-Cavity (CH)

• New development for FAIR p-linac

rf → beam power conversion efficiency

CH

conventional


Accelerating Cavities

H – Field

E – Field

rf-coupling cell

Rf-coupling of CH-cavities:

• reduce number of klystrons

• reduce place requirements

• profit from 3 MW klystron development

• avoid rf-power line splitting

• reduce cost for rf-equipment

3.0 MeV 70 MeV

1:2 Model


0

400

800

1200

1600

2000

2400

1 2 3 4 5 6 7 8 9

RF-Power Source Number

RF

-Po

wer

[kW

]

Rf-Power Requirements

Rf-frequencyReq. rf-peak powerPower to BeamPower to LoadRf-pulse lengthRepetition rate

325.224 MHz 2.5 MW 1.25 MW 1.25 MW 70 µs 4 Hz

per rf-load (incl. margin):

Time

RF

-Pow

er

9.5 µs 40 µs

2.2 MW

1.1 MW

0.5 µs0.5 µs

20 µs

• 7 Klystrons

• 2 solid state amplifiers, IOTs, ...

• 1 power converter / rf-source

RFQ

DTLB

unch

er

Bunch

er

Heat

Beam


R&D: Testing of Klystron & CH-Cavity Operation

• Choice of Toshiba klystron & CH-cavities approved by ext. committees

• But:

• CH-cavities never built

• 3 MW klystrons never operated at GSI

• Rf-test stand mandatory for testing and staff training

cavity

klystron (protection)

power supplies

radiation shielding


Beam Dynamics Layout

x /

y

[mm

]

final phase space distributions

proton beam envelopes → full transmission

OKstill too high by

35%

OK


Beam Dynamics, Losses due to Machine Errors, Hot Spots

magnet alignment

accelerating field voltage

accelerating field phase


Civil Construction

36 m

6 m

Dump

47.8 m

4 m

23.0

m

Terminal

Doo

r

Crane

Sta

irs

Klystron Gallery

Loc. Source Contrp-bar target

p-linac

Super- FRS

SIS100SIS300

HESR

CR

RESR

The FAIR Accelerator ComplexSIS 100

NESR

HESR Antiproton Prod. Target

SIS18

CR

GSI Today

RESR

p-linac SIS 300

UNILAC

FAIR


Civil Construction

47.8 m

4 m

23.0

m

Terminal

Doo

r

Crane

Sta

irs

Klystron Gallery

Loc. Source Contr

Storage, Mounting,

Media

Wall

DoorDoor

39 m

Crane

Buncher-RF

Sta

irs

23.0

m

• 1800 m2 of space required; 7700 m3

• 1200 kW of peak power consumption

• 450 kW of water cooling

• 200 kW of air cooling

Ground floor

Second floor


Steps in near Future

• Construction of prototype CH-cavity just started; ends Q3/2009

• Rf-test stand construction will start in 2008; ends Q1/2009

• CH-cavity testing in 2009 / 2010

Proton Linac, PBAR@FAIR Workshop, December 3 rd - 4 th, 2007 The FAIR Proton Linac Outline...

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