Transcript kashikhin_mu2e_solenoid

Mu2e Superconducting Solenoids
Michael Lamm
Fermilab TD/Magnet Systems Dept.
Mu2e/Comet Joint Workshop
January 24, 2009
Talk Outline
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Mu2e Magnet System Description
Present State of Magnet Design for Mu2e
Design Issues
Possible collaboration with COMET collaboration
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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History of Muon System Design
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Mu2e baseline is the the MECO solenoid system
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Several incremental improvements to design
2002-2005
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Conceptual Design completed in 2002
Cost and schedule as well as technical details
Documented in reviews and internal notes
But CDR was never updated
CDR and subsequent design improvements were
favorably reviewed several times
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Magnet System by Cryostat and Powering
•Production Solenoid
•Transport Solenoid
•Single Cryostat: pool-boiling
•Two cryostats: Indirect cooling
•Single power supply
•Four power supplies
•No iron shielding envisioned
•Kapton window
•Detector Solenoid
•Single Cryostat: Indirect
cooling
12206
Designed for
independent
cooling and
powering
•Single Power supply
25687
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Mu2e Coil Design
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System consists of 96 coil units (~80km of SSC
cable)
Fields 1-5 T, Aperture 1-2 meters, 1.5-4 kA
excitation
Very large operating margin in current
density, field and temperature
Conductor
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Structure
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SSC cable soldered into a half hardened copper
bar
Insulated with glass tape and Kapton
Stabilizer is sized for Production, Transport and
Capture target requirements
LDX Coil
epoxy vacuum impregnated
outer mandrel for hoop stress
Coils series-connected through soldered splice
joints
SSC cable
Copper Bar
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Mu2e Quench Protection
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Digital Quench Protection with analog backup
Input
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Upon quench (deviation from expect voltage over long
integration time)
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Calculated Inductance Matrix and Splice Resistance
Monitor voltage across each coil, power supply current I(t)
Extract current from quenched magnet through external dump resistor
Other magnets brought down in orderly fashion
Design peak voltage to ground (1kV)
Design peak spot temperature ~150K
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Mu2e and the MECO Magnet System
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Mu2e is studying the Meco design
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Face to face meeting with magnet designers(MITGA)
Developing proposal with General Atomics (GA) to
assemble and documents to produce an updated CDR
Time frame: 4 months
We will use this time to investigate ways to make
the Mu2E solenoid system more efficient i.e.:
– Produce more “capturable” muons/incident proton, less
background
– For less money and as quickly as possible (since the
magnet system seems to be the cost and schedule driver
for the experiment)
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Areas of Investigation from Baseline Mu2e
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Punt on the reflected pions/muons in the production solenoid
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Eliminate highest field solenoid
Forward production is swept from the magnets: less nuclear heating
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Go away from SSC conductor to wider cable
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More effective extraction, reduce the amount of stabilizer
With HTS leads, helium consumption penalty is substantially reduced
Have to weigh against added cost of HTS leads, extraction circuits, PS etc.
Use of other conductors
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Higher current, but less turns, lower inductance
May be easier to build
Sub-divide magnet system into smaller units for powering
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Indirect cooling then may be possible
For e.g., use of Aluminum stabilized conductor.
Related to this..
Look for synergies with COMET experiment
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Possible Areas of Mu2e/Comet Magnet Collaboration
Conductor development
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While there are several commonalities in the magnetic design….
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…there are significant differences in the actual magnet designs
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Common goal of maximizing clean “capturable muons”
A large driver is the conductor choice which greatly influences mechanical
and quench designs
Conductor development (Aluminum stabilized conductor) is a logical
place to consider collaboration
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Could have significant benefits for Mu2e design
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But need to make clear case for moving away from baseline
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COMET has some concerns that need to addressed about the availability and
affordability of the aluminum stabilized conductor on the market today…
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Vendors who will bid on magnet fabrication may have a preference
towards a particular technology
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Most detector solenoids in recent times built with stabilizer Al
Should be prepared to consider all reasonable proposals
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Areas of Collaboration II
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Under discussion is a proposal under the US-Japan agreement to
study muon beamline magnets
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The immediate need for a realistic detailed conductor specification
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In particular, the parts of the proposal addressing Al stabilized NbTi, are very
well aligned with the near term interests of both Mu2E and Comet.
Hopefully this program, if approved, will produce conductor in the 2010 that
would be timely for Mu2e/Comet tests and prototypes.
In the case of Mu2e, conceptual design studies with Al stabilizer should be
performed in parallel with the Meco CDR updates (i.e. in the next 6 months)
Therefore, we should develop as soon as possible a conductor specification
with realistic attainable Jc and good structural properties
Aligned with US-Japan agreement
Near term need for practice conductor
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We would ask that in the very near future, some conductor is identified, either
from surplus or available from industry that could be used to practice winding
coils in the near future. If possible this conductor should be as close as
possible to the future base line conductor.
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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Focus on Design of Pion-Production Solenoid
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Recognizing similarities in function of Pion-Production
Solenoids for Mu2e/COMET…
Using common conductor design…
Select a few design studies of mutual interests
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Possible topics:
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Quench protection of coupled solenoids under various power schemes
Heat load studies on production solenoids from particle production under
various shielding scenarios. This would require coordination with
particle production models, particle interaction models like MARS as
well as the magnet quench codes, which would be a good cross check on
the two experiments.
Agree on sensible thermal and quench margins, safe differential thermal
contractions due to quenches, based on previous detector practices.
There are probably other studies that could be proposed.
Mu2E/COMET Joint Workshop
Jan. 23-24, 2009
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