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MPP meeting
MPP meeting (04 Jun 2008)
Present: Boris Bellesia; Juan Casas-Cubillos; Nuria Catalan Lasheras; Sandor Feher; Robert Henry Flora; Karl Hubert Mess; Michele Modena; Antonio Perin; Mirko Pojer; Vittorio Remondino; Stephan Russenschuck; Roberto Saban; Nikolai Schwerg; Andrzej SIEMKO; Pierre Strubin; Ezio Todesco; Antonio Vergara Fernandez; Arjan Verweij; Louis Walckiers; Rob Wolf
Chaired by: Dr. Siemko, Andrzej
On 27/05/08 the ElQA team successfully tested the cold circuit at 1.9kVwithout the electronics connected (without C50 connectors plugged-in according to procedure). Guarantee from CRG/IN that all measurement chains had passed the HV test (1.9 kV).
On 27/05/08, one of the RB line (current lead 1 on DFBAA) failed after 90 seconds, at 1.7kV (according to the new procedure suggested by MPP), with the electronics connected. The other line (current lead 2 on DFBAA) was successfully qualified at 1.7kV, with the electronics connected.
In order to be sure that the cold circuit was still good, the ElQA team repeated the qualification of the line which failed without the electronics connected. The test was successful. Then ElQA team repeated the qualification of this circuit with the electronics connected, and it passed this time.
It is still unclear what happened in the meantime.For the time being, the RB circuit is blocked.
the gage in the Q4-D2R8, Q6R8 ,Q6L1 and Q5L1 cryostats is working. However oscillations appeared las week and are being investigated. The circuits can not be powered.
In Q5R8 the level reading stays at zero. There seems not to be an obstruction in the enclosure. The warm by-pass is going to be installed.
In Q4-D2L1 the level gage (in D2) saturates at 50% . The second gage also saturates at the same level.
New level gages have been installed in sectors 2-3, 6-7. They are being installed today in sector 3-4.
R. Saban announced that the hardware commissioning activities will not be hold by problems in the stand-alone magnets. The powering will start as soon as the arc is available and access for potential interventions related to this problem will become more difficult.
The HV test at 1.7 kV failed in the DFBA in 7R8. After 50 seconds there was a break-down that disappear later. The electronic card and the cable is being replaced and re-qualified this week. The RB circuit is thus not released for powering.
Status of DFBs in sector 8-1 A. Perin.
All the DFBs except DFBXs have been validated. A level gage in DFBXH is being replaced (mechanical damage). There are also problems with the DFBXA level gage. The temperature sensors to regulate the helium flow in the 600A current leads will arrive at the end of week 24. One week is required for equipping each box. Leads will not be disconnected.
K.-H. Mess asked if flow meters are definitively excluded. A. Perin explained that there is nothing available in the market rated for the radiation level expected in this location. A flow meter will require either new development or move the piping away from the radiation area. In both cases, the solution is not compatible with the timescale of HC.
Comparison of quench performance of the main dipoles at SM18 and in sector 5-6. E. Todesco
E. Todesco investigated the unexpected training quenches in sector 5-6.
The first estimate for the number of quenches in a string assumes no memory from training in SM18. The magnets in sector 5-6 will gat to 11kA after 40 quenches in Noell magnets, 12 in Ansaldo magnets and 1 in Alstom. The observation is 20 quenches.
The second estimate uses data only from magnets that underwent a thermal cycle. The training curve for the first 10 quenches agrees very well with the prediction but it diverges afterwards. The actual training in sector 5-6 is slower than expected.
The last estimates is statistical taking into account the virgin magnet behavior plus their correlation when tested after the thermal cycle. This gives a tendency compatible with sector 5-6 observation. We observe however a degradation for the last 10 quenches.
S. Russenschuck reminded that end spacers in the heads were modified by Alstom to fit better. 80% of the training quenches were located in the heads. S. Feher asked if de-training is correlated with batch or date. This is not clear.
Current levels for Q1,Q2,Q3,D3,D4 magnets. S. Feher
A request from AB/ABP to increase the currents above the design value for Q1,Q2 and Q3, D3 and D4 magnets was addressed by the US magnet manufacturers. (See attached minutes)
For the IT quadrupoles, the required gradient will be 222T/m and 232T/m at ultimate current. All magnets were trained up to 230T/m. However, unlike LHC conditions, training was done with energy extraction. Full energy deposition tests were done only at 215 T/m. It is not considered safe to operate above this field.
For the separation dipoles D3 and D4 the required currents are 300 A below the final training current. It does not seem to be a problem but the final current limit has not be specified by BNL. The discussion is still ongoing. Hardware will need to be changed. An ECR is being prepared by M. Zerlauth.
Special sequence for training quenches. M. Pojer
R. Schmidt suggested adding two special sequences for the RB circuit to be used during hardware commissioning. The first one will be similar to PNO.a4 but with a plateau at 12000 A to be used for training quenches. The second sequence will be a magnetization cycle to be used after a quench in the reference magnets for the RB/RQ circuits. Current will be ramped-up to 500A at 100A/s and then to 2kA at 5A/s. The current will be then ramped down at 10A/s.
MPP endorses the addition of the two sequences.
Test proposal for the correctors in LQNMA.5L8. R. Wolf
The corrector showing a high resistance in Q5L8 (RCBCHS5.L8B1) was replaced by a warm corrector (one of two spares for this type). It is suggested to repeat ElQA on this corrector after having moved the fices points of the DFBM. If the fault is If still there,other horizontal corrector in this cold mass (RCBH5.L8B1) has to be trained to 110 A to ensure we can operate at100 PO needs to be informed. There is no protection or parallel resistance in these magnets.
Update on the investigation on RQ5.L8. A. Perin
The connection of Q5 to the DFBMC is designed with the plug at the lower point to allow bubbles to go out. After observing a resistance at cold in all three 6kA bus-bars of 22 mOhms, the geometry of the line was reviewed. The external envelope did not follow specifications. The bus-bar pipe position was estimated and found almost horizontal.
The DFBM was raised by 22mm. The magnet was commissioned to nominal current following the intervention.
That said, several requests have been done concerning the training quenches in RB.A78. The frist one consist on provoking a quench in six magnets at the same time at a current just below the last achieved current. This may offer a quantitative jump on the next ramp. The reaction of the cryogenic system to a massive quench needs to be studied.It is proposed to start with three magnets. R. Denz informed that provoking the quenches cannot be done simultaneously. There will be some delay up to 400ms (50A).
Another suggestion is to quench at different temperatures. Delaying the start of energy extraction is not recommended. Evaluating this non-standard procedures should be taken over by the analysis team.
N. Catalan Lasheras 16 June 2008
Present: Boris Bellesia; Juan Casas-Cubillos; Nuria Catalan Lasheras; Sandor Feher; Robert Henry Flora; Karl Hubert Mess; Michele Modena; Antonio Perin; Mirko Pojer; Vittorio Remondino; Stephan Russenschuck; Roberto Saban; Nikolai Schwerg; Andrzej SIEMKO; Pierre Strubin; Ezio Todesco; Antonio Vergara Fernandez; Arjan Verweij; Louis Walckiers; Rob Wolf
Chaired by: Dr. Siemko, Andrzej
General information
After a quiet week, the cryogenic conditions are ok and the powering tests have resumed. The quench campaign in sector 5-6 is continuing. An ECR has been prepared on the electronic cards for temperature sensors and it will be presented on ICC next Friday.ElQA Issues and status of non conformities in sector 8-1
There is only one NC still initiated in sector 8-1: it concerns the main dipole circuit and a problem on the electronic cards of the cryo team. EDMS 925315On 27/05/08 the ElQA team successfully tested the cold circuit at 1.9kVwithout the electronics connected (without C50 connectors plugged-in according to procedure). Guarantee from CRG/IN that all measurement chains had passed the HV test (1.9 kV).
On 27/05/08, one of the RB line (current lead 1 on DFBAA) failed after 90 seconds, at 1.7kV (according to the new procedure suggested by MPP), with the electronics connected. The other line (current lead 2 on DFBAA) was successfully qualified at 1.7kV, with the electronics connected.
In order to be sure that the cold circuit was still good, the ElQA team repeated the qualification of the line which failed without the electronics connected. The test was successful. Then ElQA team repeated the qualification of this circuit with the electronics connected, and it passed this time.
It is still unclear what happened in the meantime.For the time being, the RB circuit is blocked.
Status of level measurements in DFBs and stand-alone magnets
Level gage status for the stand-alone magnets in sector 8-1. J. Casas Cubillos.the gage in the Q4-D2R8, Q6R8 ,Q6L1 and Q5L1 cryostats is working. However oscillations appeared las week and are being investigated. The circuits can not be powered.
In Q5R8 the level reading stays at zero. There seems not to be an obstruction in the enclosure. The warm by-pass is going to be installed.
In Q4-D2L1 the level gage (in D2) saturates at 50% . The second gage also saturates at the same level.
New level gages have been installed in sectors 2-3, 6-7. They are being installed today in sector 3-4.
R. Saban announced that the hardware commissioning activities will not be hold by problems in the stand-alone magnets. The powering will start as soon as the arc is available and access for potential interventions related to this problem will become more difficult.
The HV test at 1.7 kV failed in the DFBA in 7R8. After 50 seconds there was a break-down that disappear later. The electronic card and the cable is being replaced and re-qualified this week. The RB circuit is thus not released for powering.
Status of DFBs in sector 8-1 A. Perin.
All the DFBs except DFBXs have been validated. A level gage in DFBXH is being replaced (mechanical damage). There are also problems with the DFBXA level gage. The temperature sensors to regulate the helium flow in the 600A current leads will arrive at the end of week 24. One week is required for equipping each box. Leads will not be disconnected.
K.-H. Mess asked if flow meters are definitively excluded. A. Perin explained that there is nothing available in the market rated for the radiation level expected in this location. A flow meter will require either new development or move the piping away from the radiation area. In both cases, the solution is not compatible with the timescale of HC.
Comparison of quench performance of the main dipoles at SM18 and in sector 5-6. E. Todesco
E. Todesco investigated the unexpected training quenches in sector 5-6.The first estimate for the number of quenches in a string assumes no memory from training in SM18. The magnets in sector 5-6 will gat to 11kA after 40 quenches in Noell magnets, 12 in Ansaldo magnets and 1 in Alstom. The observation is 20 quenches.
The second estimate uses data only from magnets that underwent a thermal cycle. The training curve for the first 10 quenches agrees very well with the prediction but it diverges afterwards. The actual training in sector 5-6 is slower than expected.
The last estimates is statistical taking into account the virgin magnet behavior plus their correlation when tested after the thermal cycle. This gives a tendency compatible with sector 5-6 observation. We observe however a degradation for the last 10 quenches.
S. Russenschuck reminded that end spacers in the heads were modified by Alstom to fit better. 80% of the training quenches were located in the heads. S. Feher asked if de-training is correlated with batch or date. This is not clear.
Current levels for Q1,Q2,Q3,D3,D4 magnets. S. Feher
A request from AB/ABP to increase the currents above the design value for Q1,Q2 and Q3, D3 and D4 magnets was addressed by the US magnet manufacturers. (See attached minutes)For the IT quadrupoles, the required gradient will be 222T/m and 232T/m at ultimate current. All magnets were trained up to 230T/m. However, unlike LHC conditions, training was done with energy extraction. Full energy deposition tests were done only at 215 T/m. It is not considered safe to operate above this field.
For the separation dipoles D3 and D4 the required currents are 300 A below the final training current. It does not seem to be a problem but the final current limit has not be specified by BNL. The discussion is still ongoing. Hardware will need to be changed. An ECR is being prepared by M. Zerlauth.
Special sequence for training quenches. M. Pojer
R. Schmidt suggested adding two special sequences for the RB circuit to be used during hardware commissioning. The first one will be similar to PNO.a4 but with a plateau at 12000 A to be used for training quenches. The second sequence will be a magnetization cycle to be used after a quench in the reference magnets for the RB/RQ circuits. Current will be ramped-up to 500A at 100A/s and then to 2kA at 5A/s. The current will be then ramped down at 10A/s. MPP endorses the addition of the two sequences.
Test proposal for the correctors in LQNMA.5L8. R. Wolf
The corrector showing a high resistance in Q5L8 (RCBCHS5.L8B1) was replaced by a warm corrector (one of two spares for this type). It is suggested to repeat ElQA on this corrector after having moved the fices points of the DFBM. If the fault is If still there,other horizontal corrector in this cold mass (RCBH5.L8B1) has to be trained to 110 A to ensure we can operate at100 PO needs to be informed. There is no protection or parallel resistance in these magnets. Update on the investigation on RQ5.L8. A. Perin
The connection of Q5 to the DFBMC is designed with the plug at the lower point to allow bubbles to go out. After observing a resistance at cold in all three 6kA bus-bars of 22 mOhms, the geometry of the line was reviewed. The external envelope did not follow specifications. The bus-bar pipe position was estimated and found almost horizontal. The DFBM was raised by 22mm. The magnet was commissioned to nominal current following the intervention.
AOB.
The commissioning has to be done as for approved procedures. All non-standard tests need to be approved by equipment owners and approved by MPP.That said, several requests have been done concerning the training quenches in RB.A78. The frist one consist on provoking a quench in six magnets at the same time at a current just below the last achieved current. This may offer a quantitative jump on the next ramp. The reaction of the cryogenic system to a massive quench needs to be studied.It is proposed to start with three magnets. R. Denz informed that provoking the quenches cannot be done simultaneously. There will be some delay up to 400ms (50A).
Another suggestion is to quench at different temperatures. Delaying the start of energy extraction is not recommended. Evaluating this non-standard procedures should be taken over by the analysis team.
N. Catalan Lasheras 16 June 2008
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