Download SPL = Superconducting Proton Linac

Linac4 & SPL
Status of preparation and
Opportunities
M. Vretenar (R. Garoby)
MV + RG
DAPNIA 9/01/2006
SPL (1)
SPL = Superconducting Proton Linac
a 4 MW / 3.5 GeV linear accelerator to:
- increase the performance of the CERN high energy accelerators (PS, SPS & LHC)
- address the needs of future physics experiments with neutrinos and radio-active ion beams
95 keV
3 MeV
180 MeV
40MeV
-
Source
~ 350 m
83 m
10 m
H
90MeV
RFQ chopp. DTL-CCDTL-SCL
RFQ1chop. RFQ2
Front End
3.5 GeV
Normal Conducting
352 MHz
400 MeV 900 MeV
 0.65
 0.8
Superconducting
704 MHz
LINAC 4
SPL CDR2 Preliminary Layout 15.3.2005
Work in progress!
MV + RG
1
1
dump
Debunching
1 - 2 GeV to
EURISOL
Stretching and
collimation line
3.5 GeV to PS &
Accumulator Ring
(Neutrino Facility)
DAPNIA 9/01/2006
SPL (2)

Initial design (Conceptual Design
Report 1):



Revised design in progress
(CDR 2):





“optimized” for a neutrino factory
assumed the use of LEP cavities &
klystrons up to the highest energy
based on updated physics’ requests
using 704 MHz RF and bulk Niobium
cavities
in collaboration with CEA-Saclay &
INFN-Milano
to be published in 2005
Up-to-date information is available:

on the CERN EDMS

on the SPL site: http://project-
spl.web.cern.ch/project-spl/
MV + RG
DAPNIA 9/01/2006
SPL stages
Three stages are planned:

Stage 1: 3 MeV test place
 development and test of linac equipment, beam
characterization

Stage 2: Linac4


New linac replacing the present injector of the PS Booster
(Linac2)
Front-end of the future SPL
 improvement of the beams for physics (higher
performance and easier operation for LHC, ISOLDE
etc.)

Stage 3: SPL


New injector for the PS, replacing the PS Booster
New physics experiments using a high proton flux
 improvement of the beams for physics and
possibility of new experiments
MV + RG
DAPNIA 9/01/2006
Linac4 design
3MeV
DTL
Drift Tube
Linac
3MeV line
(H- source, IPHI RFQ,
chopper line)
Total Linac4:
86.3 m ,
18 klystrons
MV + RG
352 MHz
13.6 m
3 tanks
5 klystrons
4 MW
40MeV
90MeV
160MeV
CCDTL
SCL
Cell-Coupled
Drift Tube
Linac
352 MHz
25.2 m
24 tanks
8 klystrons
6.4 MW
Side Coupled
Linac
Duty cycle:
0.1% phase 1 (Linac4)
15% phase 2 (SPL)
704 MHz
28 m
20 tanks
4 klystrons
12.5 MW
4 different structures,
(RFQ, DTL, CCDTL, SCL)
2 frequencies
Beam current: 40 mA (avg. in pulse), 65 mA (bunch)
DAPNIA 9/01/2006
Linac4 Schedule
 Linac4 (160 MeV, H-) will double the intensity and brightness
of the beam out of the PSB.
 Support by the DG for a decision on construction at end 2006.
Tentative schedule:





MV + RG
2005-06 Continuation of R&D
2006 (end) Linac4 Design Report (basic design frozen)
2007 Detailed design (=execution drawings!), definition of
construction strategy, attribution of contracts
2008-09 Construction
2010 End of installation and commissioning
DAPNIA 9/01/2006
Linac4 collaborations
95 keV
Hsource LEBT
3 MeV
RFQ
40 MeV
chopper line
DTL
90 MeV
INDIA: klystron power
supplies
160 MeV
CCDTL
SCL
352 MHz
704 MHz
CHINA: quadrupoles,
bendings, buncher
transfer line to PSB
86 m
Bridge
Coupler
SCL Cells
View of the assembled DTL
Beam
2.5
Quadrupole
Coupling Cells
Numbers of ports :
- 6 for tuning plungers
- 6 for pick – ups
- 5 for post – couplers
- ? for RF – couplings
- ? vacuum system
CF – 100
CF – 100
CF – 63
CF - ?
CF - 250
SCL
Network of collaborations for the R&D phase, via EU-FP6, CERN-CEA/IN2P3, ISTC,
CERN-India and CERN-China agreements.
The same network should support the construction of Linac4.
MV + RG
DAPNIA 9/01/2006
Shunt Impedance
60
ZT2 (MOhm/m)
50
CCDTL
40
DTL
tank2
30
DTL
tank1
20
10
SCL
Effective shunt
impedance ZT2
along Linac4
DTL
tank3
0
0
20
40
60
80
Energy (MeV)
100
120
140
160
Superfish
calculation, not
scaled
The section between ~90 MeV and ~ 200 MeV is the most difficult for modern linacs:
- DTL-like structures present a sharp decrease in shunt impedance.
- Superconducting structures are not yet effective (low real estate gradient).
- Usual p-mode NC structures (CCL, SCL) at double frequency are considered expensive.
MV + RG
DAPNIA 9/01/2006
The nominal Linac4 solution:
a Side Coupled Linac
Klystron
[#]
Tanks/Kly.
[#]
Gradient E0
[MV/m]
Power/Kly.
[MW]
Energy
[MeV]
N cells/tank
[#]
1
5
4
3.00
107.42
11
1
5
4
3.06
125.16
11
1
5
4
3.15
144.16
11
1
4
4
2.59
160.2
11
Tot. Klystr.
[#]
Tot. tanks
[#]
Average Grad.
[MV/m]
Tot. Power
[MW]
Tot. Length.
[m]
4
20
4
12.46
28.02
RF power source:
MV + RG
4 MW, 704 MHz klystrons similar to SNS –
(offer from Thales)
DAPNIA 9/01/2006
More on the SCL
Chain of cells, coupled via slots and
off-axis coupling cells.
Invented at Los Alamos in the 60’s.
Operates in the p/2 mode (stability).
CERN SCL design:
Each klystron feeds 5
tanks of 11 accelerating
cells each, connected by
3-cell bridge couplers.
Quadrupoles are placed
between tanks.
MV + RG
DAPNIA 9/01/2006
Example: the SCL for SNS
MV + RG
DAPNIA 9/01/2006
Side Coupled cells
Copper units made of one half
accelerating cell and one half
coupling cell, precisely
machined (0.03mm) and
brazed.
2 half cells with magnetic field lines
1 half cell with one half bridge coupler
MV + RG
DAPNIA 9/01/2006
SNS SCL Construction
Cell precision machining on a lathe – RF measurements after machining and before brazing
CCL Module 1 Bead Pull
29
f (kHz)
24
19
14
9
4
-1
Channel No.
MV + RG
Vertical brazing in the oven – final RF tuning, bead-pull measurement of field in the moduleDAPNIA 9/01/2006
Options for CERN SCL
construction
Present status of Side Coupled Linac studies:
* Studied inside HIPPI, jointly by CERN and LPSC Grenoble.
Linac design (CERN), thermal analysis (LPSC), RF errors (LPSC, CERN), cell design.
* Cold model will be built by LPSC (2006).
* Technological model (Cu, brazed) will be built by BINP-Novossibirsk (2006).
* INFN-Naples joins now the collaboration (bridge coupler design, stability).
The construction of a Side Coupled Linac requires a difficult integration of
technologies:
Procurement of forged copper - Precision machining on Cu – First RF tuning before
brazing – Brazing – Final RF tuning.
Note that these technologies are very similar to those used for RFQ’s!
Options for construction (2007-2009):
1.
Contract with ACCEL (has built the SNS SCL).
2. Construction in Russia (some interest by BINP).
3. Construction in Italy (INFN-Na ready, INFN interest still to be checked)
4. Construction in France…?
MV + RG
DAPNIA 9/01/2006
A superconducting
alternative to the SCL?
ption
dient E0
ength
strons
dient E0
ength
strons
dient E0
ength
strons
1
Full 350 MHz
Option
DTL 5-40 MeV
CCDTL
Sec. 40-100 MeV
CCL 100-160 MeV
3.0
Gradient E0
1 16.7Length
5Klystrons
3.0
Gradient E0
2 31.5Length
9Klystrons
2.9
Gradient E0
3 32.1Length
10Klystrons
ength
21
3 2
3
SCL can have another meaning:
350/700
Full 350MHz
MHz
Superconducting
350/700 MHz
Superconducting
DTL
DTL5-40
5-40MeV
MeV
DTL
DTL
5-40
5-40
MeV
MeV
DTL 5-40 MeV
.
CCDTL
CCDTL40-84MeV
40-100 MeV SC
CCDTL
40-16040-84MeV
MeV
SC 40-160 MeV
SCL
CCL84-160
100-160
MeV
MeV
SCL
(spoke)
84-160 MeV
(spoke)
3.0
3.0
3.03.0
MV/m
3.0
MV/m
A SC section
could replace the Side16.7
16.7
16.7
16.7
m
16.7
m
55
5 5
5
Coupled,
providing that we can obtain
3.0
3.0
1.5 (effective)
3.0
MV/m1.5 (effective)
MV/m
real-estate
gradients ~2.5 MV/m.
25.4
31.5
8025.4
m
80
m
59
5
3.2
2.9
3.2
MV/m
MV/m
Needs investment
for the cryogenic
36.6
32.1
36.6
m
m
5 (1.8 10
MW)
5 (1.8 MW)
infrastructure, justified in the optics
Super Conducting Linac
80 Length
7980
97 79
Tot.
strons
24Klystrons
15 (10+5)
24
SCL tanks
(700 MHz)
MV + RG
5 (+36 15
x 100
(10+5)
kW)
m
m
of an SPL
following Linac4.
97
5 (+36 x 100 kW)
Spoke
cavities
(SC)
(350 MHz)
RF requirements:
beam power 2.8 MW 
- 20 units 100 kW, 352 MHz
- 3 klystrons 1 MW, 352 MHz
- 1 klystron 4 MW, 704 MHz
DAPNIA 9/01/2006
Spoke, 352 MHz
Focusing period in present design 90-160 MeV (FODO): ~ 1.5 m  compatible with
Triple-spoke
Triple-spoke designed at FZJ for HIPPI
(E. Zaplatine):
0.78 m cavity length for =0.5
E0T = 6.4 MV/m
no freq. jump
* Low efficiency at 90 MeV.
* Do we need a double spoke at lower
energy (but =0.35 probably too low)?
* Can we fit it in a cryostat ~ 1.2m long
(to keep focusing distance)?
* Can we feed 8 of these cavities from a
single LEP klystron?
MV + RG
DAPNIA 9/01/2006
Elliptical, 704 MHz
Elliptical cavities at =0.5 (CEA, INFN) are giving
excellent results.
Length ~ 0.9m
Designed for 12 MV/m.
* Require longer focusing period (~1.5 m).
* Low efficiency at 90 MeV.
* How many cavities can we feed with one klystron?
* We could use the SPL-CDR2 layout, with
superconducting quadrupoles and long cryostats,
but long R&D time for superconducting quadrupoles.
cryomodule
1m
1m
diagnostics,
steering
10 to 15 m
MV + RG
DAPNIA 9/01/2006
Summary for SC options
 A superconducting option is attractive for the high-energy part of
Linac4, but has to compete with the conventional Side Coupled Linac.
 As a preliminary step in order to compare options we need layouts
(mid 2006 ?) for both spoke and elliptical cavities, with a first beam
dynamics analysis to be done in the frame of the HIPPI Activity (see
ESAC recommendations).
 To compete with the SCL, average real estate gradient should be
> 2.2 MeV/m.
 The option of cold quadrupoles (as for SPL) can be considered, but
time is short to have it fully developed by end 2006.
 The RF power system can be a cost driver even for a SC linac, if one
cannot drive at least 8 cavities/klystron.
MV + RG
DAPNIA 9/01/2006
Global planning
RF tests in SM 18 of prototype
structures* for Linac4
* Quotes from R. Aymar (Jan.2005)
3 MeV test
place ready
Linac4 approval *
“… in
2006-2007, to decide on the
implementation of the Linac 4 and
any increased R&D programme,
depending on new funds made
available and on a new HR policy”
MV + RG
CDR 2
SPL approval *
“in
2009-2010, to review and redefine
the strategy for CERN activities in
the next decade 2011-2020 in the
light of the first results from LHC and
of progress and results from the
previous actions. “
DAPNIA 9/01/2006