nMPP meeting

Tuesday 24 Mar 2009, 09:00 → 10:30 Europe/Zurich

1/1-025 (CERN)

Nuria Catalan Lasheras

Slides MPP_2009-03-24.pdf MPP_2009-03-24.ppt

nMPP meeting 24 March 2009

General information

Rüdiger informed the panel that the question of the status and mandate of the nMPP is being addressed and a proposal will be discussed at the TE MB

Discussion on RB procedures - (Arjan, all)

Arjan showed the present test plan for the RB circuit (and for RQF/D, see slide), and a small list of questions, which are listed below with the related discussions.

Do we still need the PCL step?

Amalia clarified that this step is the visual recognition of the current leads, in order to spot condensation problems. It is usually carried out before the start of powering (and after ELQA). A simple phone call to Amalia will unblock the step. Everybody agreed to keep it.

Snapshots on the PLI_2 step (at 2kA)?

At the last HC day Knud proposed a cycle of measurements with 21 plateaux up to 2 kA. It is not clear whether this is a proposal for a type test for the QPS, in which case it should not be part of the general procedure in its details, but rather of a specific one to be discussed separately. In the discussion it was hypothesized that this cycle is necessary to commission the nQPS, in which case it would be a systematic test (to be performed on each circuit), and therefore it should be integrated in the general procedure. The point will have to be rediscussed in a future meeting with the presence of Knud.
In general we need to address the question of integration of the nQPS commissioning in the powering procedures

Is the name of PLI-s step appropriated?

It was made clear that whatever the name of the PLI-s step, it is wished not to change the name of the PLI-3 step as it is aready in the MTF profile

Calorimetry related questions

A discussion took place on calorimetric tests: how much preparation time do they really require? What is the best strategy?
Mike suggested to keep the calorimetry as a real quantitative measurement of the total resistance of each circuit, declining the idea of doing it on the three main circuits at once; responding to Arjan, he preferred to have the calorimetric tests done on three long plateaux at 3.5kA, 5 kA, and 7 kA, rather than on the two flat tops of PLI-s and PLI-3
It would appear that the preparation time of 2-3 days is "one off", and once that is done (before the start of the powering tests), the actual preparation before the cycle is of 4-5 hours.
Adriaan said that after calibration of the system with the valves blocked, the heat load could also be calculated with reasonable accuracy without blocking the valves, as the increased cooling due to the valve opening is rather slow and can be taken account. He added however that it is up to the cryogenics people to state whether they would prefer to keep the "blocked valve" technique as opposed to the "controlled valve" technique.
Antonio asked who is signing the calorimetry step
Nuria said it should be the cryogenics team
Walter said this should be formalised in the procedures, together with the related MTF properties and their acceptance criteria
As nobody from the cryogenics team was present, the point was not discussed further and the whole subject of calorimetric measurements will need to be revisited at one of the next meetings.

I_PNO=9300 A?

The question of the intermediate commissioning at 4 TeV was rediscussed.
Arjan noted that fixing the value of I_PNO has an impact on the procedures and needs to be sorted out
Walter reminded that this point remained open after the HC day and asked Ruediger how it was planned to go ahead
Ruediger answered the point was going to be discussed at the LMC
Karl Hubert questioned the usefulness of the intermediate energy, asking what should happen at 4 TeV to prevent us to go to 5 TeV.
Others remarked that, having less time pressure, the occurrence of anomalies could have been noticed, however Karl Hubert challenged that, recalling that it is difficult to see without knowing what to look for, and the situation is the same now. He added that the decision is a managerial one, however on the technical side the intermediate step does not seem useful and it is against the ALARA principle
After some discussion, there was a substantial agreement among the present on commissioning in a single energy step at 5 TeV with a small margin, meaning to fix I_PNO at 8600 A.

Provoked quenching during HC?

The question of the usefulness of deliberate quenches was debated. On the one hand, it was remarked (KHM) that the provoked quenching only tests the protection chain of the magnet that is being "fired". On the other hand (Walter, Mirko), it was recalled that in the past this events were useful to study the quench propagation through the sector. In this sense they may be less necessary today, if it was not that some cases of fast propagation remain to be understood.
Arjan reminded that none of the persons who had requested this tests were present, and everybody agreed to stop discussing it for the moment

AOB

Amalia informed the panel of a request of replacement of current leads in a DFBAC, for which she has been contacted. None of the present, neither her until the day before, was aware of the change. Amalia gave some further techical details as they were presented by Antonio Perin, and precised that he said he is writing an ECR. (although it would seem that the DFBAC had beem already opened)

Mirko reported that after his talk at the HC day, he has been contacted by Massimo Giovannozzi who asked for an assessment on the operability of RQT13.L5B1

The question of the upgraded ramp rate of the 60/80/120 A circuits to 1A/s was briefly mentioned. The request had originally come from Mike Lamont to improve the performance of the feedback system. The value might be difficult to achieve at high current for some convertes, however it seems this might be more of a problem during commissionig than in operation.
Therefore there might be a need to adapt the powering procedures.
It seems that all the experts are well aware of the topic.
Markus Z. is working with Quentin K. on the subject and said that the situation is under control

Reported by W. Venturini Delsolaro