LIU-SPS Beam loss, Protection & Transfer lines working
group meeting.
10th June 2015
Present: B. Balhan, J. Borburgh, R.Esposito, F. Galeazzi., V. Kain, A. Lechner, F-X.
Nuiry, F. Pasdeloup, A. Perillo-Marcone, G. Steele.
R. Esposito – TED Update (slides available here)
- all beam types have now been considered.
- temperatures shown are those for after 1 shot
- already for run 2 standard we’re above the limits, but it was decided that
this is ok since it’s for just short time periods
- run 2 BCMS is ok (no caveats)
- Run 3 beams give temperatures above 1100°C in graphite (well above
oxidation temps) and above service temperature limits in all other
materials
- maximum service temps correspond to limit in which material behaves as
it has been designed
- for aluminium in Run 2 we are just at the point where it falls off the cliff in
terms of structural strength – need to see what the effect of several
repeated shots would be on this
- in run3 we’ve already overshot the cliff edge by a long way. So we would
lose all the properties of the Al alloy and it would be like a standard alloy
- these issues can also be seen for CuBe and Cu…
- Verena asks what can be proposed? And what’s the final decision with
oxidation – particularly in run 3?
- Rafaelle replies, saying that it depends. Can work on it as they did for run
2 case and see how many shots over a year the device would see and see if
oxidation would be above an acceptable limit
- Verena wonders if it’s a good idea to do it the other way around? Tell
operations how much it can see and they limit it.
- Rafaelle says this would be hard, previous studies said oxidation was not
a factor as temp was under 800 °C, above 800 we get a different
mechanism, which would be the case for run 3
- Antonio adds that this means in the best case you get a little hole – but
then it can continue with cracks etc.
- Verena acknowledges that cracking the graphite is one thing but
questions if we’re still ruling out that it starts to burn?
- Rafaelle doesn’t think so, for him it’s unlikely we’ll burn but he can’t say
for sure. For him the major problem is that after several pulses we get
erosion, which reduces the amount of material seen which worsens the
situation for Al
- Anton asks what if the TED was in Nitrogen?
- Antonio replies that then the graphite situation would be fine but the
current TED design doesn’t allow it
- Anton continues, proposing that if materials etc. have to be changed could
the design not be changed as well?
-
-
Verena asks for verification: ‘can we just say TEDs don’t work with Run 3
beams?’
Antonio confirms this statement
Verena continues ‘but for the case of the TBSE, it has never seen 1 shot, if
it saw 1 shot can we say it wouldn’t burn?’
Antonio thinks that this would be the case but this needs to be checked
Verena wonders that since the TBSE doesn’t have as much cladding and
cooling etc. would it be possible to put it in nitrogen?
The answers is that it could be possible but it’s not a simple procedure , in
fact it would be easier to put it in bad vacuum
Verena mentions that currently there is no budget for TED consolidation
Antonio proposes that the TBSE be declared a sacrificial device which
leads to the questions of spares, do they exist and how many, which for
the time being is not known.
Verena confirms that sacrificial is fine, but reiterates that it mustn’t burn.
Verena asks how many bunches would it be possible to put on the TEDs
for Run 3? Clearly 288 is out, but would 144 or 72 be viable? Rafaelle to
look into this.
Antonio asks for clarification on the use of the TEDs
Verena reports that so far they have not seen much beam. But this year
with lots of losses it’s taken 3 weeks to set up so it’s frequently seen 144
bunches. But if we can’t take even 144 bunches safely then a new way of
operating will have to be found. Anyway on the downstream TED we can’t
go with high intensity because of tripping other instruments.
Antonio asks if he can get an Operations wish list of use for these objects?
Verena says to turn it around. Operations will take whatever they can.
G. Steele - TPSG protection of septa (slides available here)
- looks as though they will still protect suitably
- EN-STI to come up with new material proposals for upgrading the TPSGs
- New modifications to be implemented/built by Jan & co.
- Bruno to check plate & verify distance between absorber and septum
coils.
- Verena suggests that out of academic interest it would be good to
understand the link between temp and pressure rise
- Francois-Xavier thinks that CV section could maybe do the appropriate
simulations
- Gen to follow up with Yacine – lower priority
AOB
- Orbit studies and update: have seen that orbit changes between short
cycleswith faster ramp and slower ramp long cycles – maybe indicates
that there is a dipole magnet with a problem, perhaps developing an
interim short giving an odd dynamic effect. To be further investigated.
- Vacuum for TCDIs to be discussed
- Have we discussed TCDI integration timeline with David Macfarlane yet?
No, not yet, He’s starting to prepare timeline to all ls2 interventions
- Optomet test results: Mark tested it in laboratory on our type of materials
not under vacuum just to see a signal. Conclusive preliminary test – object
-
has been ordered. Due to be received mid/late summer when it will be
tested in vacuum.
10th June was scheduled LMC update – clearly not presenting today – for
the moment we’ve been put on first of July, which was as a result of Anton
saying ‘not in June’ Depends on TCDQ results from Rafaelle. Anton would
prefer the 8th July. Verena has summer student lectures, week after would
be fine. Discuss again in 1 or 2 weeks from now.
Actions:
- TEDs, can they withstand fewer bunches? (e.g. 144) Rafaelle/Antonio
- TBSE: can we modify this to be in vacuum? What spares if any exist?
- TBSG new material suggestions & verification (Gen & FX, later to Fausto).
Minutes taken by G. Steele