psb dump: proposal of a new design en – sti technical meeting on booster dumps friday 11 may 2012...
TRANSCRIPT
PSB dump: proposal of a new design
EN – STI technical meeting on Booster
dumps Friday 11 May 2012BE Auditorium PrevessinAlba SARRIÓ MARTÍNEZ
INTRODUCTION• The PSB dump was designed in the 1960’s to cope
with beam energies reaching 800 MeV and intensities of 1013 protons per pulse.
• Over the past years, the dump encountered some problems, i.e. vacuum and water leaks.
• Beam energy and intensity have been periodically increased during the last upgrades.
• A new upgrade in beam energy (2 GeV) and beam intensity (1014 particles per pulse) is foreseen for the near future.
• Consequently: a new dump is needed to cope with this last upgrade.
CONSTRAINTS•Installation and
lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
DESIGN CHOICES
LS1, LHC’s lifetime. The dump needs to be ready to be installed by August 2013
CONSTRAINTS•Installation and lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
x
x
CONSTRAINTS
•Location: dimension limitations and integration where the old dump is at present.
DESIGN CHOICES
CONSTRAINTS•Installation and
lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
CONSTRAINTS
•Reliability: minimise any risk of failure (avoid encountering the same problems than in the past)
DESIGN CHOICES
® The design has to be as simple as possible (to maximise reliability, to reduce assembly difficulties and to ease manufacturing complexity).® Not to work under vacuum.® Mechanical connections are preferred over welding.
CONSTRAINTS•Installation and
lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
CONSTRAINTS• Access: the dump core couldn’t be accessed
without a major interruption in the beam availability® no in-situ maintenance can be done® redundancies must be foreseen
DESIGN CHOICES
CONSTRAINTS•Installation and
lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
CONSTRAINTS
•Loading
Parameter Unit Current BeamUpgraded
Beam
Extraction energy E0 GeV 1.4 2
Peak current I* mA 3088.2 9650.6
Average Beam Power W=E0*I kW 6 26.7
1 Max. Beam Size H x V cm 1.64 x 5.61 1.46 x 5.16
1 Min. Beam Size H x V cm 0.42 x 0.81 0.37 x 0.71
CONSTRAINTS
•Loading
DESIGN CHOICES
® Cooling is needed to extract the almost 27 kW of average power of the future beam.® A 2 GeV proton beam requires a dump 130 cm long (when entirely made of Copper).® The diameter is defined to intercept up to 5 of the upgraded maximum beam: = 50 cm
CONSTRAINTS•Installation and
lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
CONSTRAINTS• Cooling circuit: cooling is needed to extract the
almost 27 kW of average power of the future beam▫Cooling by natural convection has been proved to be
not sufficient (preliminary analyses).▫A solution with forced air cooling is not possible
either: impossibility of having a closed air loop with enough flow in this particular area of the tunnel.
▫Water cooling is mandatory to extract the almost 27 kW of average power of the future beam.
▫The minimum cooling flow is estimated at ~2m3/h, when water at ambient temperature is used.
CONSTRAINTS
•Cooling circuit: cooling is needed to extract the almost 27 kW of average power of the future beam® Position of the cooling pipes: close to the beam axis (maximum peak of temperature), provided that radioactive activation of water is kept within acceptable limits. ® Redundancies to improve cooling reliability: 4 independent water circuits
DESIGN CHOICES
CONSTRAINTS•Installation and
lifetime•Location •Reliability•Access •Loading•Cooling circuit•Material
CONSTRAINTS
•Material:▫Does not need inert atmosphere.▫Good thermal and mechanical properties, to
optimise heat extraction and to guarantee the structural behaviour of the material.
▫Materials that have a good long term performance in a radioactive environment.
▫Galvanic corrosion in between materials.▫Erosion corrosion in pipes (max. speed of
water).
CONSTRAINTS
•Choice of material: following the principle of reliability and simplicity
DESIGN CHOICES
® Basic metal compounds Thermal and mechanical properties are well known Workability and behaviour in extreme conditions
(such as ionizing radiation) is well assessed® Candidate materials: Graphite, Aluminium, Stainless Steel, Copper, Titanium
PROPOSAL OF A NEW DESIGN
•Geometry▫Multiple-disk like geometry:
To lower the stress level To allow natural air cooling and thermal
radiation to play a role in the heat extraction from the dump
Aluminium keeps levels of energy deposited by the impinging beam low, while Copper helps to release the heat generated in the inner core and acts also as a shielding.
Cylindrical object, two meter long and 50 cm across, with two distinct parts, one meter long each.
Inner core. Disks made of
Aluminium
Outer core, made of Copper
or Stainless Steel
Structure made entirely in Copper or
Stainless Steel4 independent water circuits cool down only the first part
PROPOSAL OF A NEW DESIGN
ANALYSES*
to be confirmed by FLUKA
- Sliced core made of Aluminium, surrounded by sliced Copper parts.
- Steady State Temp reached in the core: 125°C (water cooling)
- Temp in the Cu part (surrounding the Al core): remains at 22°C
- Max temp in the external surface of the Al disks ~100°C
ANALYSES
GeometryWater
CoolingAir Cooling E escaping
Aluminium core + Copper safe risky 30%
Graphite core + Copper safe not safe 63%
Copper core + Copper safe not safe 48%
Titanium core + Copper not safe -
GeometryWater
CoolingE escaping
Latest proposal (Al + SS) safe 21%
Latest proposal (Al + Cu) safe 20 %
CONCLUSIONS
•The design proposed is the result of various iterations
•Considerable number of constraints addressed in the new design▫Placement, logistics▫Material and cooling▫Reliability
•Future design more robust▫Higher energies absorbed and dissipated▫Disruption kept to a minimum
PROPOSAL OF A NEW DESIGN
Sliced core made of Aluminium, slices 4.5 cm thick, with a 5 mm gap in between them
PROPOSAL OF A NEW DESIGN
Aluminium disks, 360 mm , 45 mm thick, 5 mm gap
Sliced Copper parts, surrounding the disks in Aluminium. 250 mm thick, outer 500 mm, inner 360 mm