Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 1
Preliminary vacuum pressure profiles for the beam gas imaging for
the LHC
Proposed design specification Pressure profiles
– Different configurations
– Different gas types Preliminary conclusions
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 2
Proposed design for the BGV for LHC
From M. Ferro- Luzzi
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 3
Required densities
Densities (averaged over 1m) that would be needed for the BGV to work adequately for some representative gas types.
Notes: since we only simulated H, O and Xe, we did this:
* A and Fgood for CO2 approximated by O3
# Fgood for Ne assumed same as for O (should be slightly better)
Can estimate performance of any other gas by estimating the Fgood from the gas with the closest A and by scaling the density with A2/3 (larger A, smaller density needed).
Reminder 1: is the molecular density, while the rate scales with the number of nuclei per cm3 !
Reminder 2: what really counts is the target thickness ( integrated along the useful z range)
Gas type A Fgood [107 cm-3]
p at 293 K [10-9mbar]
Hydrogen 1 0.002 5800 2300
Neon 20 ~0.020# 160 64
CO2 16* 0.020* 60 25
Xenon 131 0.140 7 2.6
From M. Ferro- Luzzi
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 4
First Proposed Vacuum Layout
Case of the BGV installed in 1 beam pipeFor integration reasons the total length of the installed system is fixed to 7 m
7 m
8 cmNEG
Transition 8 cm - : 4 cm
NEG
4 cm NEG
NEG Cartridges or Ion pumps
2 m
1 m
Gas Injection
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 5
NEG + Cartridges
Summary with required pressure at 293K
Q H2: 5E-5 mbar∙l/s
Q CO: 1E-5 mbar∙l/s
Q CO2: 3E-6 mbar∙l/s
Q Ne: 2.5E-6 mbar∙l/s
Q Ar: 5E-7 mbar∙l/s
NEG + Cartridges
7 mIon pumpIon pump
No pumping at the extremities
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 6
NEG Saturation consideration for CO and CO2
Injected Flux of CO2 3.00E-06 [mabr l/s] M (O2) 44 T 293 [K] R 83.14 [mbar cm3 mol-1 K-1] capacity 5.00E+15mol/cm2 q mol 1.23E-10mol/s q molecule 7.39E+13molecules/s Time to sature 1 cm2 67.67 SecondsTime to saturate all cm2 5.53E+05 Seconds
153.53 Hours
6.40 Days
Injected Flux of CO 1.00E-05 [mabr l/s] M (O2) 28 T 293 [K] R 83.14 [mbar cm3 mol-1 K-1] capacity 5.00E+15mol/cm2 q mol 4.11E-10mol/s q molecule 2.46E+14molecules/s Time to sature 1 cm2 20.30 SecondsTime to saturate all cm2 1.66E+05 Seconds
46.06 Hours
1.92 Days
Sorption capacity for D400: 0.5 mbarl for CO and CO2
Sorption capacity for MK5: 8 mbarl for CO and CO2
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 7
Other possible configuration: Differential pumping
25 cm 8 cm
25 cm 4 cm
25 cm 8 cm
25 cm 4 cm
2 m 50 cm 1 m
25 cm 4 cm
25 cm 4 cm
25 cm 8 cm
25 cm 8 cm
4 x Ion Pump 4 x Ion Pump
1) Added two new area with smaller diameter: differential pumping
2) Added a new bigger dome with flanges for the integration of ion pumps
NOBLE GASES
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 8
Other possible BGV design
Bigger tube extremities
Conical
Cylindrical
2 m 50 cm1 m
1 m 1 m 2 m 50 cm
4m 50 cm
1 m
1 m
Vacuum pressure profile for the Beam-gas Imaging for LHC G.Bregliozzi TE-VSC_LBV 9
Argon: Effects of different geometries
