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MPP meeting
Participants
Amalia Ballarino
Andrzej SIEMKO
Antonio Perin
Antonio Vergara Fernandez
Arjan Verweij
Cesare Maglioni
David Richter
Glyn Kirby
Juan Casas-Cubillos
Karl Hubert Mess
Louis Walckiers
Mirko Pojer
Nuria Catalan Lasheras
Reiner Denz
Rob van Weelderen
Rob Wolf
Robert Henry Flora
Rüdiger Schmidt
Serge CLAUDET
Solfaroli Camillocci Matteo
Stephan Russenschuck
Thiesen Hugues
Vittorio Parma
MPP meeting (30 Jan 2008)
Present: Amalia Ballarino; Juan Casas-Cubillos; Nuria Catalan Lasheras; Serge Claudet; Reiner Denz; Robert Henry Flora; Thiesen Hugues; Glyn Kirby; Cesare Maglioni; Karl Hubert Mess; Vittorio Parma; Antonio Perin; Mirko Pojer; David Richter; Stephan Russenschuck; Rüdiger Schmidt; Andrzej Siemko; MatteoSolfaroli Camillocci; Rob van Weelderen; Antonio Vergara Fernandez; Arjan Verweij; Louis Walckiers; Rob Wolf
Chaired by: Andrzej Siemko
The bypass installed by CRG in these two magnets has eliminated the erratic loss of level. However, a difference of pressure between the D line in the QRL and the LD line in the cold mass (~68 Pa) pushes down the level in its enclosure when the valve in the bypass is open. This effect has been seen in both magnets and creates a negative bias of 7%. This bias should change from magnet to magnet according to the relative height of QRL and cold mass. A second negative bias of 2.5% has to be added to take into account the static heat load. These two effects do not lower the helium level in the cold mass but only in the level gauge and imply that the maximum level reading should be around 71%. J. Casas affirms that the level can only be controlled under 65% and proposes 62% as the operational value in order to be stable (not tested yet). Following the above reasoning, this will mean around 72% in the cold mass. The coils are under liquid helium at 64% for these particular magnets.
A. Siemko asked if overflowing during the ElQA tests is acceptable for cryogenics.
S. Claudet joined the meeting and rules out overflowing as it will mean having liquid helium in the line D and will provoke the lost of cryo_start and cryo_maintain conditions. He informed the panel that both magnets have been operating at 57% and 58% in stable conditions (see slides). It is proposed then to set the operating point at 57% for both magnets and start ElQA. The level set point will be increased 1% per day and the situation will be reviewed next Friday 1st February. In this situation and assuming an underestimation of the level of ~10%, the coils should be covered. R. van Weldeeren reminds that the oscillations in the level have not been evaluated yet and the operating range still needs to be defined.
In the medium term, the differential pressure measurement should be installed to validate the bypass (estimated to half a day, should be requested to HC). In other sectors, valves on the top of the level gauge enclosure will be added to enable the installation of the bypass.
Both actions are approved by the panel.
A quench was provoked in B17R4 at 9.5 kA to test the opening of the quench release valves. Four magnets in total quenched. This was the first time a quench detector of this type was tested and it worked properly as well as all other systems. However the time for the propagation of the quench from the first (B17R4) to the second magnet (A17R4) was unexpectedly short (140ms). A first spike seen in the voltage pick-up of A17R4 is not a quench but was most probably caused by the fast ramping down of the current and an inaccurate compensation in the QPS system
A first spontaneous quench was experienced in the RB circuit at 9789 A in magnet C27L5. This quench was also followed more than a minute later by the almost simultaneous quench of two other magnets only 710 ms apart (B27L5 and A27L5).
A second spontaneous quench in the RB circuit was observed at 9859 A in magnet A22R4. This time, the propagation of the quench between magnets was slower. However this magnet is a silver magnet with a very good quench performance. S. Claudet remained the panel that the cryogenic conditions on the second unprovoked quench were not nominal (static helium instead of active cooling).
The analysis of the data is ongoing and will be continued inside the MPP analysis team.
Next meeting will be in two weeks and may take place in the CCC if powering continues in week 07.
Issues to be treated:
February 5th 2007.
Present: Amalia Ballarino; Juan Casas-Cubillos; Nuria Catalan Lasheras; Serge Claudet; Reiner Denz; Robert Henry Flora; Thiesen Hugues; Glyn Kirby; Cesare Maglioni; Karl Hubert Mess; Vittorio Parma; Antonio Perin; Mirko Pojer; David Richter; Stephan Russenschuck; Rüdiger Schmidt; Andrzej Siemko; MatteoSolfaroli Camillocci; Rob van Weelderen; Antonio Vergara Fernandez; Arjan Verweij; Louis Walckiers; Rob Wolf
Chaired by: Andrzej Siemko
General information
In the official planning, warm-up of sector 4-5 will take place at the end of next week. A possible extension into week 7 will be discussed next Friday in ICC.Status of the level gauges in the stand-alone magnets.
J. Casas Cubillos presented the results of the boil-off tests in magnets Q5 and Q6 left of point 5 (see slides). The volume coincides with the calculated values. The maximum level in the cold mass should correspond then to 81% of the level gauge.The bypass installed by CRG in these two magnets has eliminated the erratic loss of level. However, a difference of pressure between the D line in the QRL and the LD line in the cold mass (~68 Pa) pushes down the level in its enclosure when the valve in the bypass is open. This effect has been seen in both magnets and creates a negative bias of 7%. This bias should change from magnet to magnet according to the relative height of QRL and cold mass. A second negative bias of 2.5% has to be added to take into account the static heat load. These two effects do not lower the helium level in the cold mass but only in the level gauge and imply that the maximum level reading should be around 71%. J. Casas affirms that the level can only be controlled under 65% and proposes 62% as the operational value in order to be stable (not tested yet). Following the above reasoning, this will mean around 72% in the cold mass. The coils are under liquid helium at 64% for these particular magnets.
A. Siemko asked if overflowing during the ElQA tests is acceptable for cryogenics.
S. Claudet joined the meeting and rules out overflowing as it will mean having liquid helium in the line D and will provoke the lost of cryo_start and cryo_maintain conditions. He informed the panel that both magnets have been operating at 57% and 58% in stable conditions (see slides). It is proposed then to set the operating point at 57% for both magnets and start ElQA. The level set point will be increased 1% per day and the situation will be reviewed next Friday 1st February. In this situation and assuming an underestimation of the level of ~10%, the coils should be covered. R. van Weldeeren reminds that the oscillations in the level have not been evaluated yet and the operating range still needs to be defined.
In the medium term, the differential pressure measurement should be installed to validate the bypass (estimated to half a day, should be requested to HC). In other sectors, valves on the top of the level gauge enclosure will be added to enable the installation of the bypass.
Both actions are approved by the panel.
Powering of 4-5
M. Pojer presented the powering test results of last week in the main RB circuit (see slides).A quench was provoked in B17R4 at 9.5 kA to test the opening of the quench release valves. Four magnets in total quenched. This was the first time a quench detector of this type was tested and it worked properly as well as all other systems. However the time for the propagation of the quench from the first (B17R4) to the second magnet (A17R4) was unexpectedly short (140ms). A first spike seen in the voltage pick-up of A17R4 is not a quench but was most probably caused by the fast ramping down of the current and an inaccurate compensation in the QPS system
A first spontaneous quench was experienced in the RB circuit at 9789 A in magnet C27L5. This quench was also followed more than a minute later by the almost simultaneous quench of two other magnets only 710 ms apart (B27L5 and A27L5).
A second spontaneous quench in the RB circuit was observed at 9859 A in magnet A22R4. This time, the propagation of the quench between magnets was slower. However this magnet is a silver magnet with a very good quench performance. S. Claudet remained the panel that the cryogenic conditions on the second unprovoked quench were not nominal (static helium instead of active cooling).
The analysis of the data is ongoing and will be continued inside the MPP analysis team.
ELQA issues
- Sector 4-5: ElQA in L5 will start this afternoon as discussed earlier.
- Sector 7-8: a short to ground was found in a connection cryostat during cool down. Opening the interconnection and endoscopy will be done today. V. Parma noted that the thermal contraction had not yet affected the connection cryostat.
- Sector 8-1: The diode in 30R8 was open and cleaned. The debris found looks as a welding seam. The diode box is now closed and ElQA should resume on Friday.
Next meeting will be in two weeks and may take place in the CCC if powering continues in week 07.
Issues to be treated:
- Current ramp and acceleration issues.
- Inner triplet powering.
- Possibility of powering with a floating power converter.
- Changes in the powering procedures to reflect changes in the sequencer.
- Simultaneous powering of a set of circuits.
February 5th 2007.
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