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Vacuum Analysis of PS Sector 20. C. Pasquino, P. Chiggiato, J. Hansen, P. R. Demarest. outline. PS sector 20 : vacuum layout Electrical Network – Vacuum analogy: principles Vacuum simulations & results Conclusions & accomplishments Acknowledgements. PS sector 20 vacuum layout. - PowerPoint PPT Presentation
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C. Pasquino, P. Chiggiato, J. Hansen, P. R. Demarest
VACUUM ANALYSIS OF PS SECTOR 20
MTE MEETING - 13TH SEPTEMBER 2012
MTE MEETING - 13TH SEPTEMBER 2012
OUTLINE
PS sector 20 : vacuum layout
Electrical Network – Vacuum analogy: principles
Vacuum simulations & results
Conclusions & accomplishments
Acknowledgements
MTE MEETING - 13TH SEPTEMBER 2012
PS SECTOR 20 VACUUM LAYOUT
- 16 Sputter Ion Pumps (SIP) 220 l/s;
- 5 Penning gauges : VGP13, VGP13a, VGP16, VGP17, VGP18.
Goal: to evaluate how the installation of the dummy 15 is going to affect the pressure profile in the PS ring
ELECTRICAL NETWORK – VACUUM ANALOGY: PRINCIPLES
MTE MEETING - 13TH SEPTEMBER 2012
][
][][
ohm
AV R
IV
]/[
/
][
sleff
slmbar
mbar SQ
P
VACUUM ELECTRICAL NETWORK
Volume Capacitance
Conductance Resistance
Flow Current
Pressure Voltage
Qin
ELECTRICAL NETWORK – VACUUM ANALOGY:DUMMY15
CONDUCTANCE CALCULATION
MTE MEETING - 13TH SEPTEMBER 2012
ma M
RTAC2
aCC
T temperature; R gas constant; Mm molecular mass; Area of the entrance; α transmission probability;
MOLFLOW*
*program written by R. Kersevan
MTE MEETING - 13TH SEPTEMBER 2012
ELECTRICAL NETWORK – VACUUM ANALOGY: OUTGASSING DATA
Non baked vacuum line: water vapor outgassing Hydrogen outgassing (200-300 h of pumpdown) Beam losses: Ion Induced Desorption H2, CO, CO2,CH4
2
9
**
][10*3
2 cmslmbar
htQ OH
2
12
**10*3
2 cmslmbarQH
The desorption yield depends on:• the nature of the ion;• Its energy;• Its angle of impingment;• Temperature of the
substrate;• Dose (cleaning effect).
Measurements on protons by W. Fischer (Brookhaven National Labs) show a < 1. Safety factor of 10 has been considered for the simulations.
E. Mahner, PRST
MTE MEETING - 13TH SEPTEMBER 2012
EQUIVALENT ELECTRICAL NETWORK – SECTOR 20
MTE MEETING - 13TH SEPTEMBER 2012
PS SECTOR 20 SIMULATIONS: PRESENT SITUATION
1*10-9 mbar
12 days
Case Study: intervention on Septum 16, January 2012
No beam losses induced total pressure rise
H2O + H2
VGP13 VGP13A VGP17 VGP181E-12
1E-11
1E-10
1E-9
1E-8
Parti
al Pr
essu
re (m
bar)
position (-)
VGP_sim_H2O VGP_sim_H2 VGP_sim_CO VGP_sim_CO2 VGP_sim_CH4
WITH BEAM LOSSES
1E+11 p/s
VGP13 VGP13A VGP17 VGP181E-12
1E-11
1E-10
1E-9
1E-8
P (m
bar)
position (-)
VGP VGP _sim
NO BEAM LOSSES
MTE MEETING - 13TH SEPTEMBER 2012
PS SECTOR 20 SIMULATIONS: INSTALLATION OF DUMMY 15
No beam losses induced total pressure rise
VGP13 VGP13A VGP17 VGP181E-12
1E-11
1E-10
1E-9
1E-8
P (m
bar)
position (-)
VGP _sim VGP _sim_dummy
NO BEAM LOSSES
VGP13 VGP13A VGP17 VGP181E-12
1E-11
1E-10
1E-9
1E-8
Parti
al Pr
essu
re (m
bar)
position (-)
VGP_sim_dummy_H2O VGP_sim_dummy_H2 VGP_sim_dummy_CO VGP_sim_dummy_CO2 VGP_sim_dummy_CH4
WITH BEAM LOSSES
1E+11 p/s
MTE MEETING - 13TH SEPTEMBER 2012
DUMMY 15 INSTALLATION: ACTIONS AND CONCLUSIONS
The simulations shows that the installation of dummy 15 is not going to have a major impact on PS sector 20 pressures profiles;
The installation of extra pumping group is not needed: the current vacuum system is going to cope with the gas loads coming from the dummy 15;
Contingency: installation of a blind flange in case of future need.
Acknowledgements: M. Hourican, J.-M. Lacroix, S. Damjanovic, S. Gilardoni.
