Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)
description
Transcript of Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)
![Page 1: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/1.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
1
Vacuum observations during the 75 and 50 ns bunch spacing operation
(MD 17-20 Nov 2010)
V. Baglin, G. Bregliozzi, P. Chiggiato, J-M. Jimenez, G. Lanza
CERN TE-VSC, Geneva
1. 75 ns bunch spacing2. 50 ns bunch spacing
3. Test ramp with 50ns_109b_12_90_12bpi10inj2. Conclusion
![Page 2: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/2.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
2
1. 75 ns bunch spacing
![Page 3: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/3.jpg)
LHC beam commissioning 19 nov 2010 3
Stacking 48b to 680 with gaps of 1.85 microsec• Injection of 24+24 bunches separated by 75 ns and 225 ns between b24 and b25• 1.85 µs between trains• Machine full with 2x680b after 14 injections
![Page 4: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/4.jpg)
LHC beam commissioning 19 nov 2010 4
Stacking 48b to 680 with gaps of 1.85 microsec• Average bunch current 0.9 E11 p/bunch• Below interlock level (4e-7 mbar) when machine filled with 2 x 680 b• Mainly pressure increases at D1 and less in other areas• Stayed for ~ 2h before beam dumped
![Page 5: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/5.jpg)
LHC beam commissioning 19 nov 2010 5
Conditionning at 680b1+680b2
• Reduction of ~ a factor 2 at D1 LSS2 and LSS8
![Page 6: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/6.jpg)
LHC beam commissioning 19 nov 2010 6
Pressure increase with machine full
• Linear trend in pt1, 3• Except for pt2, pt 8 where threshold at ~ 70 mA (248+248 b)• No pressure increase in pt5 & 7
![Page 7: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/7.jpg)
LHC beam commissioning 19 nov 2010 7
Pressure increase comparison
• Threshold at 9-10 1010 p/b for 75 ns beams• Beam conditioning Losses ?
![Page 8: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/8.jpg)
LHC beam commissioning 19 nov 2010 8
VGPB.2.5L3.B
Ellipse 52x30 mm
BPMWE
![Page 9: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/9.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
9
2. 50 ns bunch spacing
![Page 10: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/10.jpg)
LHC beam commissioning 19 nov 2010 10
Pressure increase comparison
• Higher slope for 50 ns than 75 ns• A factor 2 between the slopes
![Page 11: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/11.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
11
3. Test ramp with 50ns_109b_12_90_12bpi10inj
![Page 12: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/12.jpg)
LHC beam commissioning 20 nov 2010 12
Fill 1500 – 19th November • Only SR desorption • in LSS2• in LSS3&5• In LSS6&7
![Page 13: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/13.jpg)
LHC beam commissioning 20 nov 2010 13
Fill 1500 – 19th November • Pressure increases at VGI in A4L1• But remains lower than 7E-10 mbar
Bunch lengthincreases
SR at ~ 2 TeV
Bunch lengthdecreases during ramp
Up to 1 TeV
![Page 14: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/14.jpg)
LHC beam commissioning 20 nov 2010 14
Fill 1500 – 19th November • During ramp, bunch length decrease at 19:36 and flattens at 19:40
![Page 15: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/15.jpg)
LHC beam commissioning 20 nov 2010 15
Fill 1500 – 19th November • Some activity in MKIR8 intermodule stimulated by ramp and SR• Start ramp, pressure increase starting from ~ 550 GeV (19:36)• But flattens at 800– 1000 GeV (19:40)
Bunch lengthincreases
SR at ~ 2 TeV
Bunch lengthdecreases during ramp
Up to 1 TeV
![Page 16: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/16.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
16
Same ramp the 31th October
![Page 17: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/17.jpg)
LHC beam commissioning 20 nov 2010 17
Fill 1459 – 31th October • 50ns_109b_12_90_12bpi10inj - Trains well separated i.e. no discussion between trains• Pressure up to 2e-8 mbar
![Page 18: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/18.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
18
4. Conclusions
![Page 19: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/19.jpg)
LHC beam commissioning 20 nov 2010 19
Conclusions
• 2x680 b were injected with 75 ns, pressure remained below interlock level• Beam conditioning was observed during ~ 2h storage time• At 75 ns, threshold around 9-10 1010 p/bunch
• At 50 ns, the pressure rise per mA is ~ 2 x the 75 ns pressure rise per mA
• The test ramp of 50 ns_109b_12_90_12bpi10inj exhibits no pressure rise larger than 7 10-10 mbar
• Beam conditioning is ongoing
![Page 20: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/20.jpg)
LHC Beam Commissioning WG- 23 Nov 2010
20
Backup slides :Same ramp the 31th October
![Page 21: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/21.jpg)
LHC beam commissioning 20 nov 2010 21
Fill 1459 – 31th October • 50ns_109b_12_90_12bpi10inj - Trains well separated i.e. no discussion between trains• Pressure up to 2e-8 mbar
![Page 22: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/22.jpg)
LHC beam commissioning 20 nov 2010 22
Fill 1459 – 31th October • 50ns_109b_12_90_12bpi10inj - Trains well separated i.e. no discussion between trains• Pressure increases due to ecloud in the 1e-9 mbar region
SR at ~ 2 TeV
![Page 23: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/23.jpg)
LHC beam commissioning 20 nov 2010 23
Fill 1459 – 31th October • 50ns_109b_12_90_12bpi10inj - Trains well separated i.e. no discussion between trains• Pressure 4e-9 mbar
SR at ~ 2 TeV
![Page 24: Vacuum observations during the 7 5 and 50 ns bunch spacing operation (MD 17-20 Nov 2010)](https://reader035.fdocuments.us/reader035/viewer/2022062501/56815f48550346895dce25e4/html5/thumbnails/24.jpg)
LHC beam commissioning 20 nov 2010 24
Fill 1459 – 31th October • 50ns_109b_12_90_12bpi10inj - Trains well separated i.e. no discussion between trains
SR at ~ 2 TeV