The FAIR Proton Linac

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Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

The FAIR Proton Linac

Outline





Requirements to Proton Linac



Source, RFQ, DTL, RF



Beam Dynamics



Civil Construction

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

p
-
bar
target
p
-
linac
Super
-
FRS
SIS100
SIS300
HESR
CR
RESR
Unilac
The FAIR Accelerator Complex
SIS 100
NESR
HESR
Antiproton
Prod. Target
SIS18
CR
GSI Today
RESR
p
-
linac
SIS 300
UNILAC
FAIR
100 m

FAIR:
F
acility for
A
ntiproton and
I
on
R
esearch

7

10
10

cooled pbar / hour

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007


<=100 x :

4 x :

I
njection of
protons into SIS18

Acceleration to 2 GeV

Injection into SIS100


Acceleration to 29 GeV

Impact on target


hot pbars

Stoch. pbar cooling in CR

Injection into in RESR



Injection into HESR

Acceleration to 14.5 GeV

or

Deceleration in NESR to 30 MeV

Extraction to low energy pbar experiments


Accelerator Chain for Cooled Antiprotons

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007



η
MTI

→ 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
~ size
2

~
γ
-
1

)

η
MTI

:=
green area

/
red area

= filling factor

SIS18



Injection energy

duration
→ current → emittance
ε

are coupled

Energy remains to be chosen

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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-Duty SIS100 [%],
Cooled pbar
Rate [10^9/h]
0
5
10
15
20
25
30
SIS18 Space Charge Limit [10^12]
SIS100 Duty Time
Cooled pbar / h
SIS18 Space
Charge Limit
final rate of cooled pbar depends on injector energy:

70 MeV

→ 16.5 mA / µm →



I = 35 mA



βγ
ε
x

= 2.1 µm

limited by stoch. cooling power

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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 energy

Beam current (op.)

Beam current (des.)

Beam pulse length

Repetition rate

Rf
-
frequency

Tot. hor emit (norm.)

Tot. mom. spread

Linac length


70 MeV


35 mA


70 mA


36 µs



4

Hz

325.224 MHz

2.1 /
4.2

µm


±


-
3

≈ 35 m

Diagnostic
insertion

95 keV
3 MeV
70 MeV
Source
LEBT
RFQ
CH
-
DTL
Re
-
Buncher
to Dump
to SIS18
Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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 Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

Proton Source & LEBT

Proton energy

95 keV

Proton current

100 mA

Max. rep. rate

4 Hz

β
γ
ε
tot
(transv.)


1.8 µm

High reliability

High stability

Requirements at LEBT exit:

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

95 keV

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

R
adio
F
requency
Q
uadrupole (RFQ)

3.5 m

4
-
rod (cheaper)


164
480

164
480
164
164
480
4
-
vane (state of the art)

Two designs followed:

Both designs meet requirements

0.1 MeV

3.0 MeV

+V
+V
-
V
-
V
~
Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

D
rift
T
ube
L
inac 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

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

0
10
20
30
40
50
60
70
80
90
100
0
20
40
60
80
Proton Energy [MeV]
Zeff*<cos(phi)^2> [MOhm/m]
rf
-
power
→ beam power

Accelerating Cavities



C
rossed
-
bar
H
-
Cavity (CH)



New development for FAIR p
-
linac

rf
→ beam power conversion efficiency

CH

conventional

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

0
400
800
1200
1600
2000
2400
1
2
3
4
5
6
7
8
9
RF-Power Source Number
RF-Power [kW]
Rf
-
Power Requirements

Rf
-
frequency

Req. rf
-
peak power

Power to Beam

Power to Load

Rf
-
pulse length

Repetition rate


325.224 MHz


2.5 MW


1.25 MW


1.25 MW


70 µs


4 Hz

per rf
-
load (incl. margin):

Time
RF
-
Power
9.5 µs
40 µs
2.2 MW
1.1 MW
0.5 µs
0.5 µs
20 µs


7 Klystrons



2 solid state amplifiers, IOTs, ...



1 power converter / rf
-
source

RFQ

DTL

Buncher

Buncher

Heat

Beam

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

Beam Dynamics Layout

x

/ y [mm]

final phase space distributions

proton beam envelopes


full transmission

OK

still too high
by 35%

OK

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

Beam Dynamics, Losses due to Machine Errors, Hot Spots

magnet alignment

accelerating field voltage

accelerating field phase

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

Civil Construction

36 m
6 m
Dum
p
47.8 m
4 m
23.0 m
Terminal
Door
Crane
Stairs
Klystron Gallery
Loc.
Source
Contr
p
-
bar
target
p
-
linac
Super
-
FRS
SIS100
SIS300
HESR
CR
RESR
Unilac
The FAIR Accelerator Complex
SIS 100
NESR
HESR
Antiproton
Prod. Target
SIS18
CR
GSI Today
RESR
p
-
linac
SIS 300
UNILAC
FAIR
Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

Civil Construction

47.8 m
4 m
23.0 m
Terminal
Door
Crane
Stairs
Klystron Gallery
Loc.
Source
Contr
Storage,
Mounting,
Media
Wall
Door
Door
39 m
Crane
Buncher
-
RF
Stairs
23.0 m


1800 m
2

of space required; 7700 m
3




1200 kW of peak power consumption



450 kW of water cooling



200 kW of air cooling

Ground floor

Second floor

Proton Linac,
PBAR
@
FAIR Workshop, December 3
rd
-

4
th
, 2007

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