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LIU-TT2 meeting 2 (cycling time, EYETS installation)
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Europe/Zurich
865/2-C19 (CERN)
Present: K. Hanke. S. Pittet, G. Sterbini, H. Damerau, Q. King, K. Papastergiou, D. Bodart, D. Cotte
K. Hanke introduced the two topics of the meeting:
1.) Compatibility of the new converters with possible non-baseline scenarios for the SC composition (presented by D. Cotte)
2.) Present status of the TT2 prototype converter and plan of its test in 2017 (presented by K. Papastergiou)
1.)
One of the specifications of the LIU-TT2 power converters is the possibility to undergo a degaussing cycle within the minimum time between two TT2 extractions. Presently this condition occurs when a 14 GeV SFTPRO is followed by a TOF cycle and corresponds to Tmin=1.06 s. The new system has been designed to cope with this figure.
The present system has an erratic behaviour for this Tmin. There was a discussion about the limited reproducibility of the problem: D. Bodart excluded the ageing of the magnet and observed that the cooling circuit is stabilised to 7 deg. K. Papastergiou commented that this behaviour could be associated with the temperature dependence of the magnet resistance.
The operational solution is to put an additional constraint to the SC composition (TOF-like cycle cannot follow SFTPRO-like cycle).
With the new BTRAIN system the Tmin can be potentially reduced by a almost a factor two. K. Hanke and H. Damerau commented that this scenario is not a baseline scenario. Even though the functional specification and the design of the TT2 converters are to be based on the baseline configuration (that stays unchanged), it is interesting to understand the factors that limit the performance when reducing the Tmin.
S. Pitted commented that most probably the bottleneck for Tmin<1.06 s is related to few power converters. K. Papastergiou commented that one could start from the present observation and evaluate the present and future performance limit. In order to progress in this direction OP will provide an example of the problematic SC [ACTION1]. D. Cotte and H. Damerau will provide this information to K. Papastergiou and discuss in the next LIU-TT2 an updated table of Tmin in different cycle configuration.
Q. King asked if one could have a faster degaussing by acting on the DC cable resistance. K. Papastergiou commented that the load resistance is largely dominated by the magnet and therefore this countermeasure would have a marginal effect. K. Papastergiou will follow-up with the input of the next meeting.
2.)
K. Papastergiou reported that the construction and installation of a prototype power converter is progressing and the installation of the new converter is compatible with the present schedule.
Q. King informed that the software of the FGC3 controller is still to be finalised. The last issues of the design were addressed but due to the work load of his section the software will be not ready for the restart. The software for the double PPM operation will be ready only in the second part of the year (in any case 2017 prototype, the QFNO215, is single PPM).
The objective for 2017 is to have the prototype power converter running under operational conditions for several weeks. It will be another spare for the present TT2 converter. S. Pittet commented that the old spare will be still available in case of problem and namely during the first part of the operation when the FGC software will not be ready.
The new power converter will have a dummy load for test/debugging purpose in case of problem.
To validate the new converters before the LS2 connections a dummy load as representative as possible to the real load should be used. For that reason [ACTION2] D. Bodart will provide a non-activated spare magnet to be used as a test load.
The next meeting will be held on 22 March 2017 (detailed agenda will follow).
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