Key SCRF Cavity R

1
Key SCRF Cavity RD Issuesand Infrastructure

• Mark Champion
• May 18, 2009

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Outline

• Introduction to key issues and infrastructure
• Performance goals for Project X and ILC
• Key SCRF cavity RD issues
• Key infrastructure for SCRF cavity RD
• Summary

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Key SCRF Cavity RD Issues

• Achievement of high gradients with high yields
• Materials
• Fabrication techniques
• Processing techniques
• Diagnostics and testing
• Understanding mitigation of limitations (quench
  and field emission)
• Achievement of production rates needed to
  constructProject X and support ILC RD
• Development of new cavity designs for Project X
• 1.3 GHz, beta0.8, elliptical cavity
• 325 MHz, beta0.6, triple-spoke cavity
• 325 MHz, beta0.4, single-spoke cavity

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Key SCRF Cavity RD Issues (contd)

• Cost reduction
• Design
• Fabrication techniques
• Processing
• Development of high average power RF couplersfor
  Project X

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Key Infrastructure for SCRF Cavity RD

• Processing Testing Facilities
• ANL/FNAL cavity processing facility
• Vertical test systems (IB1 A0)
• Horizontal test system
• JLab and Cornell cavity processing and testing
  facilities
• Single-cell processing RD facility
• installation in progress at FNAL IB4 see
  Cooleys talk for more information
• Processing Equipment
• Vacuum oven for hydrogen degassing
• 600-800 deg C, planned ARRA procurement
• Low temperature baking system (120 deg C)
• Cavity tuning machine
• under development as FNAL/DESY/KEK collaboration
  due end of 2009
• Cavity tumbling machine

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Key Infrastructure for SCRF Cavity RD (contd)

• Diagnostic and Repair Equipment
• Cavity interior optical inspection system
• Temperature mapping system
• Laser system for defect repair
• Materials Characterization
• Eddy-current scanning system
• RRR measurement apparatus
• Tensile strength and hardness testing equipment
• Microscopy and surface analysis equipment

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Baseline processing sequence illustrates the need
for many of the infrastructure elements
Quench
FE
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More details provided in the following
presentations

• Breakout Presentations (day 1)
• Cavity development - Champion
• Spoke resonator development under HINS - Webber
• Couplers - Solyak
• Processing facilities - Rowe
• VTS - Ginsburg
• HTS Harms
• Plenary Presentations (day 2)
• SRF Technology Development Program - Cooley
• Industrialization - Carter

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Project X Cavity Requirements
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ILC GDE SCRF Program Goals

• TDP1 technical feasibility by 2010
• Gradient (S0) to reach 35 MV/m with 50 yield
• One cryomodule (S1) to achieve average gradient
  of 31.5 MV/m
• Proof-of-Principle and System Engineering
• Cryomodule design with plug-compatible components
• TDP2 technical credibility by 2012
• Gradient (S0) to reach 35 MV/m with 90 yield
• One-RF unit (three cryomodules) operating with
  beam (S2)

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Achievement of high gradients with high yields

• Two fundamental problems
• Field emission
• Defect-induced quench
• Field emission generally results from particulate
  contamination, but can also result from sharp
  surface features that cause local field
  enhancement (for example, a scratch in the high
  electric field region of the iris)
• Field emission can be controlled through
  optimized, repeatable cavity handling and
  processing procedures
• Examples of success recent nine-cell cavities
  at JLab and single-cell cavities at ANL/FNAL
• Defect-induced quench is generally due to
  geometric defects pits or bumps near the
  equator weld
• May also result from foreign materials,
  thermally-isolated features, and scratches or
  machining marks
• Examples to follow

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Achievement of high gradients with high yields
(contd)

• The quench problem is not just a problem of new
  cavity vendors. It also appears from time to time
  in Accel (RI) cavities, e.g., Accel15.
• But Accel clearly is more successful than its
  competitors in producing defect-free cavities.
  How?
• Horizontal electron beam, assembly weld
  sequence, pre-weld annealing (?), other
  proprietary techniques
• Our RD is aimed at solving this problem via
  experiments with
• Samples ( 3 x 3 inches)
• Single-cell cavities
• Nine-cell cavities
• Try different techniques with samples and
  single-cell cavities
• Apply to nine-cell cavities
• Process test cavities with diagnostics to
  understand limitations
• See Lance Cooleys talk for additional information

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Summary of nine-cell cavity performance
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What limits cavity performance?Usually field
emission or defect-correlated quench
Excellent recent results at Jefferson Lab in
processing and testing of Accel nine-cell cavities
Performance results after one bulk plus one light
electro-polish All good except A15, which
quenched at lt20 MV/m due to defect near equator
weld
A15 defect
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First test result on AES5 at Jefferson Lab(2nd
AES production of nine-cell cavities)
quench
Mode measurements ? cell 3 or 7 Other cells
achieved 31-44 MV/m Next steps T-map cells 3 and
7 then inspect
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AES5 Defect PhotoCell 3, 700 um diameter, 8 mm
from weld seam
Another case where performance is limited by a
defect near the equator weld
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But all defects are not equal!

• TE1AES004 has huge pit at edge of equator weld,
  size 1mm
• Nevertheless it achieved 39 MV/m

equator
TE1AES004
HPR and reassembly only
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Many cavities are needed to conduct cavity RD,
build cryomodules, and develop vendors

• Initial cavity orders were placed with Accel
  (2005)
• 24 nine-cell and 6 single-cell cavities
• We are working with North American vendors AES
  and Niowave/Roark to develop their capabilities
• Both vendors qualified on single-cell cavities in
  2008 (6 each)
• AES has delivered 10 nine-cell cavities another
  6 in fabrication
• Niowave/Roark is fabricating 6 nine-cell cavities
• PAVAC has produced coaxial cavities for TRIUMF
  and is getting started with single-cell 1.3 GHz
  cavities
• Cavity procurements funded by SRF budget (not
  ILC)
• ARRA funds will be used to procure 40 nine-cell
  cavities
• See my breakout talk for more information

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Cavity inventory and planned procurements
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1.3 GHz Cavity Coordination

• FNAL/ANL cavity process/assembly/test high-level
  scheduling tool
• Used to optimize/integrate operations for 1-cell
  and 9-cell 1.3 GHz cavities

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Americas Cavity Coordination

• FNAL/ANL JLab Cornell cavity coordination
  tool
• Cavity status tracking
• Cavity performance
• http//tdserver1.fnal.gov/project/ILC/S0/web/Cavit
  y_Listing.asp

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Achievement of production rates needed to
construct Project X or support ILC RD

• Project X cryomodule construction is planned for
  3 years
• Drives production rate of one beta1 cryomodule
  per month
• Utilize cavity processing and testing
  capabilities at JLab and ANL/FNAL
• infrastructure upgrades needed to increase
  production rate
• Collaborate with MSU, ANL, JLab and Indian
  Institutions on production of betalt1 cryomodules
• Move some cavity processing steps to industry
• as planned for XFEL, where cavities will be
  delivered ready for vertical test, with helium
  vessels already installed
• Develop improved processing procedures, for
  example, tumbling plus chemical-mechanical
  polishing instead of electro-polishing
• See talks by Allan Rowe and Sergei Nagaitsev for
  additional information

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Development of new cavity designs for Project X

• 325 MHz single-spoke and triple-spoke cavities
  will be presented in Bob Webbers talk
• Design principles for the 1.3 GHz beta0.81
  cryomodule
• The beta0.81 cryomodule design will be based on
  the Fermilab Type-4 cryomodule
• Strive to maintain compatibility and similarity
  between the beta0.81 and beta1.0 cryomodules
• Sharing of components ? reduced development and
  construction costs
• Start with the beta0.81 cavity design that was
  prototyped at MSU
• MSU will process test two seven-cell prototype
  cavities
• Optimize the cavity design with respect to
• Number of cells
• Cell geometry and coupling
• HOM spectrum and HOM damping requirements
• Multipacting
• Integration with Type-4 cryomodule design
• Work to be done in collaboration with MSU and
  Indian Institutions

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RF Couplers for NML cryomodules are procured in
collaboration with SLAC

• 12 couplers of the TTF-3 design have been
  produced by CPI and are undergoing inspection,
  cleaning, and RF processing at SLAC
• These will be used in the construction of CM-2
• Additional coupler procurements are planned using
  a combination of ILC and ARRA funds
• Design modifications are planned to increase the
  average power capability to meet Project X
  requirements
• A good proof of principle is the Cornell ERL
  coupler, which is also based on the TTF-3 design,
  and has been tested up to 60 kW CW

TTF-3 RF Coupler
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RF Coupler design for Project X is driven by
average power requirement
Peak power is constant average power
increases. See Nikolay Solyaks talk for more
information.
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Argonne/Fermilab CavityProcessing Facility is
Operational
Electro-Polishing
Ultrasonic Degreasing
High-Pressure Rinsing
Assembly Vacuum Leak Testing
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Commissioning of the Argonne/Fermilab
CPFSingle-cell cavity processing testing
results
ANL/FNAL cleanroom starts
TE1ACC003
TE1ACC001
TE1AES004
TE1AESC004
TE1ACC002
TE1AES005
NR-4
TE1ACC002
NR-1
TE1ACC001
TE1ACC002
SC01
TE1AESC004
TE1AES005
TE1AESC004
TE1ACC002
Post baking
Post-baking
Pre-baking
Pre-baking
Post-baking
Pre-baking
Post-baking
Post molding
Post-baking
TE1AESC004
BCP No baking
RF retest
Test Number
Little or no field emission in recent tests
?Commissioning with single-cell cavities is
complete
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Test rate is increasing at theFermilab Vertical
Cavity Test Facility

• gt40 cavity tests in FY08/FY09, where test
  cryogenic thermal cycle
• 9-cell single-cell 1.3 GHz elliptical cavities
  and 325 MHz HINS single-spoke resonators
• instrumentation development, variable coupler,
  thermometry, cavity vacuum pump system, cavity
  vendor development
• Many cavity tests dedicated to ANL/FNAL CPF
  commissioning ? presently engaged in 9-cell
  process commissioning

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VCTF upgrade is planned with civil construction
scheduled for this summer
existing cryostat radiation shield
Very similar to Feb.2007 plan

• Increase cavity test throughput
• Current throughput estimate 48 cavity tests/year
  
• Increase throughput to gt200 cavity tests/year by
  Oct 2011
• Planned upgrades
• Improve cryogenic system reliability
• Reduce interference with magnet test program
• Two more cryostats and staging area
• See Camille Ginsburgs talk for more information

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The A0 VTS was recently commissioned for 1.3 GHz
single-cell cavities and augments the IB1 VTS
This system has been used for 3.9 GHz cavity
testing, and was recently modified for 1.3 GHz
single-cell cavities.
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The Horizontal Test Stand is operational and we
plan to build a 2nd HTS to support Project X

• Accomplishments
• Commissioned for 1.3 and 3.9 GHz cavities
• Four 3.9 GHz cavities tested in 2008 ? installed
  in cryomodule for DESY
• Capability to be expanded with addtion of HTS2
• Ready to Operate in 2012
• See Elvin Harms presentation for additional
  information

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The KEK/Kyoto optical inspection system is
operational at Fermilab

• KEK/Kyoto inspection system delivered, installed,
  commissioned early in 2009
• Expert assistance to optimize system in March
  2009
• In routine use software development underway

Accel7 on the optical inspection stand
Optical inspection optimization
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New single-cell temperature mapping system uses
multiplexed diodes as sensing elements
New diode based system with 960 sensors and 62
wires can be installed in about 15 minutes
Traditional carbon resistor based system
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Summary

• An overview of the key SCRF cavity RD issues and
  related infrastructure - in the context of
  Project X and ILC RD - was presented
• The foremost cavity RD issue is the achievement
  of high gradients with high yields, and this is
  where we are focusing our efforts
• The infrastructure for conducting cavity RD is
  largely in place, and we have plans for several
  upgrades to increase capacity
• Presently engaged in nine-cell process
  commissioning at ANL after very successful
  single-cell commissioning earlier this year
• We plan to utilize ARRA funds to procure
  additional cavities, RF couplers, and a vacuum
  oven
• The cavity RD work is being pursued in
  collaboration with JLab, Cornell, ANL, MSU, SLAC,
  TRIUMF and several university groups
• We are well-positioned to support the Project X
  and ILC RD programs over the next few years