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