lcls-ii vacuum system specification
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LCLS-II Vacuum System
M.J.Ferreira
Vacuum Science and Engineering Dep. Head
Mechanical Engineering and Technical Support Division
2
Outline
• Introduction,
• LCLS-II vacuum systems,
• Specifications for each system,
• Vacuum schematic fast valves,
• Lessons Learned,
• Hazards,
• Conclusions.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
3
Introduction
Conceptual Design for LCLS-II phase II Vacuum systems.
Main objectives:
• Clarify SLAC and partner laboratories interfaces of the vacuum
hardware,
• Review main specifications of sub systems and vacuum
instrumentation,
• Define interface: particle free and non particle free regions.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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LCLS-II Project
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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LCLS-II project
IVC-19 Paris, September 9-13, 2013
Include LCLS-I
experience for the
injector: wave guide
windows, load
windows, vacuum
instrumentation for
fast response.
Old LINAC, a lot of
modifications along
the years:
necessary to
document and re-
simulate the
vacuum.
Noble gas for gas
attenuator soft X-ray:
Ar, Kr, Xe and Ne upto
50 Torr, windowless.
Use the exiting
PEP-II high
energy bypass
line.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Basic Energy Science Advisory Committee
M. J. Ferreira LCLS-II Vacuum System CDR March 20th, 2014
LCLS-II project was reviewed and July/2013 presented to follow BESAC
recommendations at the Report on Future X-ray Light Sources.
• LCLS-II Phase II
CDR
September 2013
• LCLS-II phase II
Cost Review
January 22-24, 2014
• LCLS-II phase II
CD-1 DOE Review
February 4-6, 2014
Partner Laboratories:
ANL (undulator chambers)
Cornell Lab (gun)
FNAL (Cryo modules)
JLAB (Cryo modules)
LBNL (gun)
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LCLS-II phase II
LCLS-II CD-1 DOE Review, Feb 4-6, 2014
SXU
HXU
proposed FACET-II LCLS-I LCLS-II SC Linac
cross-over bypass line m-wall
A-line
B-line Sector-10 Sector-20 Sector-30 Sector-0
extension line L3 L2 L1
s (m)
Injector SRF Linac Transport Beamline
Dumps
Undulator hall
From BESAC report:
“It is considered essential that the new light source have the pulse
characteristics and high repetition rate necessary to carry out a
broad range of coherent “pump probe” experiments, in addition to a
sufficiently broad photon energy range (at least ~0.2 keV to ~5.0
keV).”
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LCLS-II phase II Vacuum systems
CM01 CM2,3 CM04 CM15 CM16 CM35
BC1
L = 92 m
R = 10 mm
BC2
L = 140 m
R = 10 mm Injector source Length = 2.1 m
Radius = 20 mm
LH L = 32 m
R = 10 mm
L0 L1 HL L2 L3
LTU
3.9GHz
L3 extension
L = 20 m
R = 24 mm
Differential
pumping
Diag. Line Diag. Line
Distribution
line
Pressure Requirements
Average Nitrogen equivalent Pressure:
Injector:
Injector source <1 x 10-10 Torr
SRF cryo modules beam line <1 x 10-10 Torr
Coupler <1 x 10-9 Torr
Thermal isolation <1 x 10-5 Torr
Laser Heater (inside low-particle region of the SRF) <1 x 10-9 Torr
BC3 extension <1 x 10-8 Torr
L3 to Bypass section max 1 x 10-8 Torr
Straight Ahead Beam max 1 x 10-7 Torr
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Vacuum Systems
The vacuum system of the LCLS-II phase 2 is consisted of 4 independent systems:
• The beam line system: is the vacuum related to the beam path along the machine,
including the injector, all cavities and instrumentations until the end-user stations. It
requires the lowest pressure at the injector and at the SRF section including, low particle
and leak rate requirements and restricted gas composition (LBNL, FNAL, JLab and
SLAC).
• The vacuum system for the couplers: what is design around each coupler as UHV
standard with ion pumps and TSP (FNAL and JLab).
• Thermal isolation system: is the cryostat vessel where all the thermal isolation is
contained including the cooling lines and the cavities (FNAL and JLab).
• The thermal isolation of the Cryogenic Distribution System (FNAL and JLab).
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Coupler Vacuum
The system is part of the cryo module assembly
(FNAL and JLab) and will include:
- The manifold to the couplers,
- The pumps (ion pumps and TSP),
- The pump down valve (angle valve),
SLAC will be responsible for the cables and
controllers. The pump down process, including
the turbo cart system will be SLAC responsibility.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Injector Source
The system is a Very-High Frequency
gun (APEX) with the instrumentation
from LBNL, what will include all
vacuum hardware:
- Gun and load-lock system,
- All gauges, RGA and pumps,
- All diagnostic instrumentation.
SLAC will be responsible for the
cables and controllers. The pump
down process, including the turbo cart
system will be SLAC responsibility.
LBNL will work on the free particle condition and the vacuum performance of
the gun.
SLAC is working to help the 3D vacuum simulation for the VHF gun (APRX)
pump configuration and vacuum instrumentation.
Molflow +
Base pressure <10-11 Torr
Operation pressure <10-9 Torr
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Thermal Isolation vacuum system: cryo module
The thermal isolation of the cryo
modules will be provide by FNAL
and JLab, what will include the
following vacuum hardware:
- All vacuum gauges and isolation
valves,
- All the electro-pneumatic gate
valves (for each cryo module) for
pumping down the thermal
isolation,
- Burst disk for the thermal
isolation,
- Beam line pipe connecting the
cavities including the angle valve
and burst disk,
- Manual gate valves for the
cavities,
SLAC will be responsible for the cables and
controllers. The pump down process,
including the turbo cart system will be SLAC
responsibility.
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Thermal Isolation vacuum system: cryo module
SLAC will be responsible for:
- The roughing pump carts to pump down the thermal isolation,
- The turbo system attached directly to the thermal isolation to keep the
pressure in case of some unpredicted high outgassing or leaks.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Thermal Isolation vacuum system: distribution line
SLAC will be responsible for the cables and controllers. The pump down
process, including the turbo cart system will be SLAC responsibility.
FNAL will be responsible to design and
deliver the distribution line including all
valves, instrumentation and assembling
process.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Beam Line Vacuum
The Beam line vacuum will be a mix of LBNL, FNAL, JLab and SLAC parts what will include
the injector source, cryo module cavities, interconnections and warm sections.
• All the warm section will be responsibility of SLAC, from the vacuum flange of the cryo
module on.
Cleanliness requirements are pointed as procedures to follow for certification of free-particle
contamination of parts, assembling and installation process. A common ground about
procedures should be clearly state among the laboratories to assure equivalent results.
Specific point of contact are desired for easy communication.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Beam Line Vacuum: differential pump X particle free region
At the actual stage the warm section design is envisioned the cleanliness near the cryo
modules as:
• Differential pumping and,
• Particle free region.
The warm section contains a series of instruments what some times can present technical
challenges to accommodate the cleanliness requirements.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Particle free regions
Vacuum Guide lines:
• All materials and instrument shall be UHV
compatible,
• Able to be clean for particle free,
• No vacuum connection for external
systems (EX. Wave guide for T-cavity),
• Valves and vacuum gauges qualified for
particle free.
Pump down cart and venting:
• Specific turbo cart to run the pump down,
• Specific arrangement for venting process
• Specific configuration for leak detection,
Procedures among partner laboratories in
these subject can help SLAC to accomplish
the task in the cost and available time frame.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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L3 extension
The L3 extension will be using both solutions and a fast valve:
• Differential pumping,
• Particle free region.
The distance from the cryo modules to the L3 to Bypass (“DogLeg”) is around 300m.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Fast valve system:
CM01 CM2,3 CM04 CM15 CM16 CM35
BC1
L = 92 m
R = 10 mm
BC2
L = 140 m
R = 10 mm GUN Length = 2.1 m
Radius = 20 mm
LH L = 32 m
R = 10 mm
L0 L1 HL L2 L3
LTU
3.9GHz
“BC3”
L = 20 m (2 km)
R = 24 mm
Fast signal: commercially
available cold-cathodes
for 3-4 ms from 10-11 –
10-7 Torr pressure rise.
Fast valve: commercially
available, radiation
resistant, UHV standard,
<10 ms (from signal to
leak tight).
Minimum distance 10 m. FS1
FS2 FS3 FS4 FS5 FS6 FS7 FS8
FV1 FV4 FV5 FV6 FV7 FV8 FV2 FV3
FV – fast valve
VS – fast signal
*
Isolation
vacuum
system
In case of a catastrophic failure, the fast valve system should be
able to close the valves (tight) before the gas wave reaches the
cryo module.
N2 gas speed (main gas in air) at room temperature 400 m/s, time
for 10 m distance 10 m/400 m/s = 25 ms.
*Only at the Gun injector a technical solution for a 2 m section
presents a question to be addressed more carefully.
The control system is able to answer much faster <1 ms.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Lessons Learned
1. RF wave guides connected directly to the beam vacuum.
The vacuum requirements of a RF wave guide is substantially
different from the Beam line vacuum, and a physical barrier should be used
(EX: ceramic windows). The performance of the RF gun of the cavities can
be compromised as happened with LCLS-I RF gun.
LL: by design the Beam line will be physically separated from all other
vacuum systems.
2. Vacuum instrumentation (Cold-cathode and RGA) can change their
calibration and/or sensitivity over time. Any fixed set points or interlock can
be compromised, if regular maintenance and check up aren’t predicted.
Some cold-cathode gauges from Klystron was indicating measurements
under lowest limit, but the gauge sensor was actually damage.
LL: Schedule checks for cables, controllers and sensor heads.
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Hazards
Cryogenic:
Failure/rupture of cryogenic system from overpressure, mechanical damage, insufficient
or improper maintenance, improper procedures.
Probability after mitigation: remote
Mitigating Factor: design cryogenic per ASME, ANSI and SLAC Pressure Safety
program.
Applicable areas: Cavities, warm beam line, thermal isolation vessel (burst disk, relief
valves).
Accelerator Beam line:
Catastrophic loss of vacuum, cooling water, compressed air.
Probability after mitigation: remote
Mitigating Factor: engineered safety system to protect beam line from vacuum, cooling
water and/or compressed air faults.
Applicable areas: all vacuum systems interlocks, redundant systems and valves.
Accelerator system, mechanical system:
Compressors, pumps, cavities, HVAC, bake out and vacuum equipment failures.
Probability after mitigation: occasional.
Mitigating Factor: Separate areas from specific operation areas, isolation of
operation/experimental process, personnel safety devices (electrical, noise, etc).
Applicable areas: all vacuum systems and power supplies (HV).
M. J. Ferreira OLAV IV, Hsinchu, Taiwan, April 01st – 4th, 2014
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Conclusion
• A vacuum guide line need to be prepared among
laboratories to standardize vacuum equipment and
instrumentation,
•Action list need to be address to clarify interfaces and
point of contact for communications for the vacuum
systems,
•A series of documents need to prepared to cover all main
specifications, assembling and procedures among the
labs.
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