Transcript Document 7720699

Phase II Collimators: design
status, options and future
outlook
LHC Collimation
Phase II
10th Design Meeting
Alessandro Bertarelli
Alessandro Dallocchio
19th September, 2008
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Overall time plan
…excerpts from last LHC MAC (R. Assmann talk)…
Scheduling:
 Define general directions until July 08.
 Prepare conceptual design until October 08.
 Discuss conceptual design and organize project details in

November 08.
 Testing of hardware in 2009/10 (lab and beam tests).
 Time plan will be (is already?) affected by start of LHC
beam operation (highest priority to make phase 1
collimation system work).
Important milestone: Review of conceptual design with
parallel development paths in late autumn 2008.
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Functional Specification
 Phase II present boundary conditions:

Minimal
system

New Secondary collimators (TCSM) to be placed immediately
downstream of Phase I Secondary collimators (TCSG)
 Stands, electric and water connections already available
 Same interfaces as Phase I
 Affecting only IP 3 and IP7 (~ 30 units), no modifications to SC
areas.
 Additional collimators and modifications in SC areas may
be required to overcome intensity limitations.
Phase II goals (our interpretation):
 Gain factor ≥10 in cleaning efficiency.
 Gain factor ≥10 in impedance.
 Gain factor ≥10 in set-up time (and accuracy?).
 Radiation hardness and easy handling.
 Improved geometrical stability (in operating conditions) 20 mm
 Sufficient robustness (like Phase I?).
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A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Functional Specification
Design Guidelines as we see them …

Modular concept to fit in alternative jaw materials (All-metal, Metaldiamond, Ceramics-metal, Thin foil etc.) and concepts (alternative
cooling systems)



Increase geometrical stability and precision (e.g. jaw flatness).

Collaboration with external partners to identify, develop and test novel
advanced materials (EPFL, Plansee, Politecnico di Torino, Kurchatov,
BNL)

Possibility to embed in jaw design Beam diagnostic devices (BPMs,
BLM(?) …)
Increase cooling capacity.
Capitalize Phase I experience to improve existing design (e.g. new
moving tables)
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Baseline of the design
Preliminary design is based on the concept of a back stiffener remaining at
uniform temperature and ensuring geometrical stability of the jaw beam.
Fine adjustment System
Metal support
(cooler)
Jaw+cooling
system
Rigid Support (backstiffener)
Jaw
(monolithic case shown)
Back stiffener
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Baseline of the design
Main components of Phase II jaw assembly:
 Back-stiffener
 Fine adjustment system
 Equipped Jaw
 Collimation Jaw
 Jaw Cooling system
 Beam diagnostics devices
 RF system
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Molybdenum Back-stiffener
The design is already at an advanced stage, Mo seems to
be the best candidate. PLANSEE confirmed the feasibility
of this component (10-12 weeks to produce a prototype).
Fine adjustable system
support
fastened to plates
Stiffener material requirements:
Minimise thermal bending
Low CTE
High thermal conductivity
Minimise deflection provoked by
the force in the adjustable system
High Young’s modulus
MOLYBDENUM
Stiffener ribs
fastened to plates
A. Bertarelli – A. Dallocchio
Stiffener plates
(~1.1 m long; up to 20 mm
thick)
LHC Collimation Phase II – Design Meeting – 19/09/2008
Fine adjustment system
…feasibility of Mo screws confirmed by PLANSEE…
Cooling pipes on the
stiffener plates
(geometrical
stability)
Fine adjustment
system (overall
deflection controlled)
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Jaw and cooler: Design options
…depending on RF and cleaning efficiency specifications…
Possible alternative solutions for TCSM
Equipped Jaw
Ceramic absorber with metallic
(conductor) support
Jaw absorber: Ceramic
1.
2.
3.
4.
5.
0.1-10 Wm resistivity
Few cm long tiles
~5 mm thick
~1 mm gap between tiles
CTE ~5 ppm
Solid metal jaw
Ceramic support with thin
foil absorber (conductor)
Monolithic jaw
1.
2.
3.
1.2 m long
Very good conductor on surface (e.g.
Cu coating)
Bulk material should have low CTE
(Metal – Diamond?)
Ceramic support
1.
2.
Jaw metal support
1.
2.
3.
Low conducting material
Monolithic or brush-like
Thin-metal foil
Good conductor
1.2 m long monolithic
CTE matching ceramic’s?
1.
2.
bonded to support
~20-50 mm thick
Jaw Cooler & Pipes
1.
2.
Continuous pipes brazed
to Jaw cooler (as Phase I)
A. Bertarelli – A. Dallocchio
Cooler Length ~500mm
Brazed to metal support or integral?
Embedded continuous
pipes (back-casting)
Machined Circuit with
brazed cover
Machined circuit sealed
during casting
LHC Collimation Phase II – Design Meeting – 19/09/2008
Collimation jaw
RF studies have not yet clarified the choice between high/low electrical
conductivity materials. Options for high or medium density materials (collimation
efficiency) still open.
Possible design options:
 Monolithic metallic jaw (Glidcop) – Studied.
 Monolithic Cu-diamond + Cu coating – Being studied


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Plansee available for advanced co-design (investment necessary?)
Monolithic Al-diamond + Al coating – Being studied

Collaboration with EPFL already launched:
Development of Al-CD jaw + Al coating + Al-CD cooler with Zr or Inox pipes. Mock-up
possibly available within few weeks.
Ceramic tiles on metal support – Being studied

Ongoing research of suitable ceramic materials following preliminary spec. by RF
experts (SiC is expected to be a good candidate)
Thin metal foil on low conducting support – To be studied

Preliminary RF studies show that no major difference exists between monolithic metal
jaw and thin metal foil bonded on low conducting support. Possible advantages in
terms of robustness
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Collimation jaw
Ceramic absorber with metallic (conductor) support…
Metallic support
Ceramic tiles
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Jaw Cooler and pipes
Increased energy deposition (high / medium density jaw materials)
requires much higher cooling capacity with respect to Phase I (factor
~5)
Design alternatives:



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Machined circuit with brazed covers (Glidcop or Cu-Diamond) – studied.


High cooling capacity, relatively easy production.
Not in line with UHV recommendations → …(Remark: Plansee developed and qualified
a very similar solution for ITER project in a similar environment)
Continuous bent pipes back-casted in metal diamond – being studied


Plansee available for co-development using Ta or Nb pipes in Cu-CD (investment
required?)
EPFL also working on this option using Zr or Inox pipes in Al-CD
Machined circuit sealed during casting – To be studied
Continuous bent pipes brazed to jaw cooler – Derived from Phase I
solution
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Jaw Cooler and pipes
Cooling circuit
machined in metal
support with brazed
covers
Cooling pipes backcasted in metal
support
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A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
BPM integration
Integration of BPMs into the jaw assembly gives a clear
advantage for set-up time
BPM pick-ups
BPM cables and
electrical
connections
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A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
RF contacts
RF stability provided by ferrite blocks and metallic rails (no sliding
contacts)
Ferrite blocks ensure beam
stability without sliding contact
Ferrite blocks placed
all along the jaw
Metallic rail
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A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Thermo-mechanical analysis
Fine adjustable system: preliminary thermo-mechanical analysis for
8e10 p/s scenario confirm the validity of the design principle (back
stiffener + collimation jaw).
Max deflection:106 mm
Max ΔT: ~30 C
Mo back-stiffener
Cu cooling system
Cu jaw
Max deflection:80 mm
A. Bertarelli – A. Dallocchio
Temperature is
underestimated due to
unrealistic boundary
conditions!!!
LHC Collimation Phase II – Design Meeting – 19/09/2008
Future Outlook
Our view on future activities …
1.
Back stiffener / central adjustment principle seems so far a viable solution  We continue
on this path
2.
RF studies have not yet allowed the choice between high/low electrical conductivity
materials  keep all material options open (metal, ceramic, thin foil).
3.
Effects of material density on global collimation efficiency not yet clarified  options for
high (Cu) or medium (3÷5 kg/dm3) density materials still open.
4.
Cooling system: we prefer the machined solution (more efficient and feasible); back-casted
option should be kept only if a clear veto on machined solution is emitted.
Keeping options 2, 3 and 4 open has a cost in terms of required design
manpower.
5.
BPM pick-ups embedded in jaw assembly seem attainable; BLM to be evaluated only if
compact enough to be hosted in collimator jaw  reduction in jaw effective length
6.
7.
8.
Jaw robustness for the moment relies on +/-10 mm external tank translation.
Increase reliability of actuation system by new moving table design.
Continue/strengthen collaboration with EPFL and Plansee.
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008
Future Outlook
To-do list …
In order to meet the challenging objectives and deadlines of this
project the following points should be rapidly addressed:

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


Tracking studies followed by Fluka analyses for all possible scenarios (nominal
and accident), designs and jaw materials:
Cu/CD + Cu coating
Al/CD + Al coating
Ceramic tiles (+ Thin foil)
Most
urgent
Decision on cooling circuit solution (involving AT-VAC and SC-RP)
Gear up in RF studies to rank different options (unfortunately E. Métral team
has lost a ad-hoc PhD candidate).
Validate BPMs baseline to go ahead with Jaw design. Evaluate BPM possibilities
Consolidate contacts with interested institutes (Kurchatov, BNL) for irradiation
studies on advanced materials.
A. Bertarelli – A. Dallocchio
LHC Collimation Phase II – Design Meeting – 19/09/2008