Helsinki, 1792007

1
Overview of accelerators for EURISOL

• Alberto Facco (INFN-LNL)
• on behalf of the EURISOL DS Accelerator Tasks

Participants and contributors INFN-Legnaro, IPN
Orsay, CEA Saclay, SOREQ NRC, TRIUMF, GANIL,
Frankfurt University, LMU, LPCCaen.
2
EURISOL Accelerators

• Proton Driver it must deliver the high power
  primary beam used for RIB production in the
  dedicated RIB target sources
• Post-accelerator it must bring the low power
  Radioactive Ion Beam to the different
  experimental points, at the required energy (from
  a few keV to 150 MeV/u)
• the accelerator specifications are determined by
  technical and experimental requirements coming
  from RIB sources, RIB preparation apparati, RIB
  intensity calculations and from the final users
• Both accelerators are Superconducting and present
  challenges that are at the frontier of the
  present accelerator technology

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The EURISOL facility
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Proton Accelerator
Collaborators INFN-LNL, IPNO, CEA, SOREQ, TRIUMF

• The baseline driver-beam options
• 1 GeV, 4 MW protons on a neutron converter
  target
• 1 GeV, 100 kW protons on a direct target
• Additional options
• 2 GeV 3He on a direct target
• 125 A MeV heavy-ion beam with A/Q 2
• 250 MeV deuterium driver beam (converter option)
  
• multi-user operation

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Baseline scheme with extended capabilities

• 2 injection lines for H,D, He and A/q2 ions
• SARAF scheme up to 60 MeV/q
• IPNO scheme from 60 to 140 MeV/q
• CEA scheme from 140 to 1000 MeV/q
• cw beam splitting at 1 GeV
• Total length of the linac 240 m

4 MW H-
B stripper
Elliptical 704 MHz
1 GeV/q
RFQ 176 MHz
HWR 176 MHz
3-SPOKE 352 MHz
H-
100 kW H, 3He2
?0.47
?0.3
?0.09 ?0.15
?0.65 ?0.78
H,D, 3He
1.5 MeV/u
foil stripper
60 MeV/q
140 MeV/q
gt200 MeV/q D, A/q2
10
36
31
63
97
6
LEBT

• Modified SARAF-type scheme, with confluence of 2
  lines
• Beam energy 20 keV/u

• source 1 (TRIUMF-type)
• H- 5 mA
• D- 5 mA
• source 2
• (commercial ECR)
• H 5 mA
• D 5 mA
• 3He 0.1 mA

Schematic of the modified SARAF injector

• Heavy Ion beams with A/q?2 (up to Calcium) also
  possible with last generation ECR sources

7
RFQ and low-? section

• SARAF-type176 MHz RFQ
• Ein 20 keV/u, Eout1.5 MeV/u

The SARAF-NTG RFQ

• 176 MHz low-? Superconducting Half-Wave
  Resonators
• Ein1.5 MeV/u, Eout 60 MeV/u

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II (Medium-low ?) 60?140 MeV/q III (Medium-?)
140?300 MeV/q IV (High-?) 300?1000 MeV/q

• Resonators prototypes developed by EURISOL DS
  participants
• A/q?2 up to 250 MeV/q, and A/q?1.5 up to 1 GeV/q

IPNO cryostat design and SPOKE resonators
IPNO-CEA-INFN 5-cell cavity
schematic of the elliptical 5-cell cryomodule
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60 MeV Error analysis - d
no losses (intermediate design)
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60 MeV Error analysis - p
no losses (intermediate design)
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Deuteron extraction

• Deuteron extraction can be achieved at 125 MeV/q
  by replacing one medium-? cryomodule with a
  dipole
• Negligible D- neutralization at this energy
• The H- and 3He beam transport is not affected
  by this modification
• Feasibility demonstrated, final layout still
  under study

normalized rms emittance
D extraction section layout
4 MeV -2 GeV 3He beam
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EURISOL 1 GeV Multiple Extraction

• 3 splitting stations for cw proton beams
• 4 simultaneous users
• 1 ? 4 MW
• 3 ? 0?100 kW

EURISOL parallel cw Proton extraction
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New 1 GeV proton beam splitter

• new splitter for high power, cw proton beams
• it allows parallel extraction to different
  targets
• no choppers nor kickers
• finely adjustable beam intensity in the secondary
  lines
• low beam losses

See dedicated talk by R. Paparella today 1010
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SARAF 0?5 MeV section commissioning at SOREQ
(model for the low-? section of the EURISOL
Driver)
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SARAF injector - SOREQ NRC
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The SARAF SC HWRs and Solenoids mounting
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SARAF LEBT emittance measurement
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SARAF - protons emittance preliminary results
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SARAF - deuterons emittance preliminary results
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Task 7 main achievements Summary

• Proton Accelerator design scheme defined
• New, cost effective, baseline design with
  extended Driver capabilities
• New beam splitter design that allows multiple
  users of high power, cw proton beams
• New design requirements from physics tasks
  fulfilled

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Beam preparation
q/m selection
Ion cooling and bunching
to Post-acceleration and Experimental areas
Electrostatic deflection
Charge breeding EBIS and ECR
Target-ion sources
High-resolution separators
Primary beams from Driver
A. Jokinen talk tomorrow 1215
Pre-separators, beam gates
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Heavy-Ion Accelerator
Collaborators GANIL, Frankfurt University, IPNO,
LMU, INFN-LNL, LPCCaen

• New specifications
• 3 separate post-accelerators for radioactive
  Heavy Ion beams
• VLE (lt1 MeV/u - to the Physics and
  Instrumentation Task)
• LE (1-5 MeV/u), and HE (150 MeV/u) to Task 6
• The Beta-beam injector will be a separate
  machine, studied outside Task 6
• No stripping foils for normal use but only as an
  option for physics applications

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Design of the HE post-accelerator
SPIRAL-2 philosophy Smoothest beam
dynamics (regular FDO lattice, low number of
?-sections), Modular solution and simple
cryostats, Separated vacuum (safety with FP),
Warm focusing (easier for alignement),
Possibility to insert diagnostics at each period,
ease of tuning
Main technical requirements Only 2-gap cavities
(high q/A acceptance) Max. accelerating fields
7.8 MV/m Nominal operation for A/Q between 4 and 8
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SPIRAL-2 88 MHz QWRs
ß0.12 88 MHz
ß0.07 88 MHz
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Normal conducting RFQ injector

• New NC RFQ for EURISOL under design, based on the
  MAFF technology
• MAFF RFQ Injector under testing at the MAFF test
  stand

MAFF RFQ
See next talk by H.Zimmermann
Steerer
Quads
LEBT tank
ion source
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Superconducting RFQ injector

• The superconducting RFQs in LNL are now in
  operation on the PIAVE injector
• Some beam parameter measurements have been
  performed
• To account for the lower voltage (20 kV instead
  of 350) of the EURISOL post-accelerator injector
  platform, a third RFQ (NC) is required. This RFQ
  is under design.

Envelopes of the new RFQ, based on the 4vane
Spiral2 design
LNL PIAVE RFQ
PIAVE
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Travelling-wave chopper

• Solution I Travelling wave chopper
• Description
• Association of a static B-field steerer and a
  100-O stripline
• - Beam always deflected by the B-field,
• - HV pulse in the stripline allows one bunch to
  pass
• Duty cycle lt 10 (instead of gt 90 !),
• Power consumption lt 5 kW,
• Power losses lt 400 W per plates,
• No pulse, no beam in the LINAC.
• Limitations
• Coverage Factor lt 75 ,
• Present max. power dissipation per ceramic plate
  electrode 100 W (SPL),
• Pulser High Voltage lt 2 kV _at_ Duty Cycle lt 1
  ,
• Attenuation overshoot of the pulse along its
  propagation (effects on the deflection ?),
• Effect of the E- and B-field superposition on
  the beam emittance ?
• Status under development.

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C-type chopper

• Solution II C-type chopper
• C-type chopper
• Description
• Electrode divided in small plates driven by fast
  switchers.
• Limitations
• Present max. power dissipation into commercial
  switches around 1kW (water cooled),
• Effective total capacitance (plates,
  connections, switch) 70 pF,
• Many feedthroughs (vacuum ?),
• Max repetition rate of switches lt 1 MHz _at_ 2.5 kV
• One switch per plate,
• No pulse, all the beam in the LINAC.
• Status under study.

• Perspective
• Full beam dynamic studies,
• Development test of a TW 100-O stripline,
• Tests of pulse generators.

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Beam Dynamics Design without strippers Simulatio
n results
Phase space and beam distribution at the end of
the linac

• No emittance increase
• No halo increase
• No losses
• All user requirements are reached, except the
  lt0,1 energy spread.
• Optimization still in progress to reach this goal

Beam envelopes
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Post-Accelerator Beam Dynamics results
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Task 6 main achievements Summary

• Design and beam dynamics validation of the SC
  linac, based on the SPIRAL2 technology.
  Requirements (except for ?E/Elt1) reached without
  strippers
• NC RFQ and injector under the first beam tests at
  Frankfurt Univ.
• SC RFQ and injector tested on PIAVE facility
  Adaptation to EURISOL under design
• High frequency chopper under design Prototype
  to be ordered at the end of 2007

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Task 8 SC cavity development
Collaborators IPNO, INFN-LNL

• Objectives
• design, fabricate and test fully equipped
  superconducting cavities (following the
  recommendations of the proton driver group and
  the heavy ion accelerator group)
• study, build and test at 4.2 K a complete
  cryomodule, as they are foreseen to be used in
  the Eurisol driver or heavy ion linac.

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Task 8 mandate "Study at first priority the
technical open problems related to the
construction of complete cryomodules"
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Half Wave Resonator development _at_ LNL

• 2 prototypes at ?0.17 and ?0.31 and 352 MHz
  fabricated and successfully tested at 4.2 K.
• The same design, by simply doubling the cavity
  length, leads to ?0.09 and ?0.16 resonators
  suitable for the low-? section of the Driver
  linac.

HWR tuner
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Spoke cavities development _at_ IPN Orsay

• 2 prototypes at ?0.15 and ?0.35 fabricated and
  successfully tested at 4.2 K.
• This technology is the basis for the 3-Spoke
  required by the Driver linac

Spoke cavity tuner
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Triple Spoke cavity development _at_ IPN Orsay
A preliminary RF design for beta 0.49 exists and
an adaptation to the optimum beta for the Eurisol
linac is in progress
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Solid state amplifier development _at_ Legnaro

• Modular mosfet technology with low-cost
  circulators included, developed at Orsay and
  Legnaro, unconditionally stable
• Design, construction and test of 3, solid state
  RF amplifiers _at_ 352 MHz

Second amplifier 10 kW
Third amplifier 10 kW
First amplifier 5 kW
under construction
Constructed tested
Constructed tested
330 W Modules
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IPN Orsay Power coupler design for Spoke HWR

• broadband
• Nominal power up to 12 kW
• Design power 20 kW
• Capacitive coupling for CW operation
• Maximum reflection coefficient S11 lt -35 dB
• Window cooling capabilities
• Relatively simple design for reliability and
  cost reasons
• same design for spoke and half-wave resonators

3 units fabricated High power test autumn 2007
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Cryomodule development
1st test (low power) in july 2007 with ?0.15
spoke cavity equipped with tuner validation of
the tuner and cryogenic performances
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Task 8 main achievements Summary

• ?0.17 and 0.31, 352 MHz Superconducting Half
  Wave Resonator (HWR) designed, constructed and
  tested
• ?0.15 and 0.35, 352 MHz Superconducting Single
  Spoke Resonator designed, constructed and tested
  Triple Spoke Resonator under development
• Cold tuning system and Power coupler for both
  cavity types designed and constructed, under
  testing
• Solid state RF amplifiers 5 kW and 1 10 kW
  prototypes designed, constructed and tested 2
  10 kW unit under construction
• Cryomodule development Test cryostat
  constructed and low-power tested with a fully
  equipped Spoke cavity

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Conclusions

• The EURISOL accelerators design and the RD in
  critical components are progressing. A large
  amount of studies, prototypes and new ideas have
  been produced within the EURISOL DS accelerator
  tasks framework
• Significant improvements were introduced in
  comparison with the old design, both in the
  Driver and in the Post-Accelerator
• The path to fulfill all the accelerator
  requirements is traced in a large part
• Hard work will be still necessary to complete the
  design, especially in the accelerator-sources
  interface it is time to converge!