Date post: | 31-Dec-2015 |
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Changes to IR6 dump protection elements
B.Goddard, W.Weterings, C.Maglioni, R.Versaci, T.Antonakakis, R.Schmidt,
J.Borburgh, J.Blanco, plus many other colleagues
Contents
• TCDQ upgrade– Absorber material and length– Movement bellows– Controls
• Additional TCLA• Buttons in TCSG
TCDQ upgrade• Issue with robustness of present TCDQ design– Dynamic stresses exceed limit for damage at block corners– Graphite jaws, 1.8g/cc– Replace with graded Carbon Composite (1.4g/cc and 1.65
g/cc)
Absorber composition
1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12
1.8 g/cc 1.8 g/cc 10.8 g/cc.m
1.65 g/cc 1.4 g/cc 1.4 g/cc 1.65 g/cc 1.65 g/cc 13.9 g/cc.m
• Lower density and higher yield stress material – should be below damage limit for beyond ultimate beams– FLUKA and stress analyses ongoing to derive limits
• Total amount of material seen by beam increases from 10.8 kg/cm2 to 13.9 kg/cm2– Should be better for asynch dump protection
Beam
Location of extra module
• More difficult upstream, due to dump line interference, but would like to maintain location of TCSG and drift to Q4, so will extend upstream.
Another benefit?
• Will have 9m of CC next to beam at location with largest H beta function– Could help reduce damage elsewhere in case of
major failure– Being investigated by J.Blanco & R.Schmidt
Improve present bellows (±20 mm)
• Presently large mechanical stress to displace• Distortion of RF fingers (away from beam!)
Will make double bellows system -> TE/VSC?
Controls
• Don’t expect any change in movement precision with 9m long absorber (10.4m)
• Are investigating an upgrade of controls to use collimation stepping motor system and low-level (although some other issues have been solved with existing DC motors)– Needs mechanical changes, and there is concern
about precision attainable in open-loop.
Justification for TCLA
• “Not needed for beam cleaning” – Ralph• Two remaining justifications
– Reduce scale of quench if asynch dump• FLUKA studies in progress
– Help contain damage if “beyond design” failure• Energy tracking, retrigger failure
• Decision still to take – when is deadline for Coll project?– Would be good to do all IR6 work together in LS1 (TCSG
with buttons, new TCDQ plus motorisation, TCLA)
Buttons in TCSGs
• Requested by Ralph• Can only support this– Will need to investigate ‘servo’ of TCDQ position
with TCSG, beyond certain offset, if TCSGs are automatically adjusted