Vacuum at the ESRF. current activities that benefit from simulation models

Transcription

1 Vacuum at the ESRF current activities that benefit from simulation models H.P. Marques - 64th IUVSTA Workshop Leinsweiler 2011

2 Vacuum at the ESRF Overview of the ESRF Vacuum group activities MC simulation for Coating Time based MC simulation for pressure bursts Cell pressure profile simulation

3 The ESRF in numbers Vacuum at the ESRF 3 rd generation synchrotron 6 GeV e m long 32 cells 35 active beam lines For a uniform filling mode 200 ma beam current Average pressure < 10-9 mbar Beam life time h dominated by Tousheck scattering ~200h due residual gas scattering L/s pumping speed installed

4 ESRF Vacuum Group Vacuum at the ESRF Vacuum diagnostic tools and interlocking systems Vacuum systems dimensioning and simulation for the beam lines users and the accelerator complex Vacuum chambers coatings (NEG, Gold, TiN) Vacuum measurements Pumping speed Pressure gauges calibration Photo desorption Thermal desorption (outgassing) NEG coating characterization

5 Sputtering Simulation Sputering from 3 cathodes at (-19, 0, 19 mm) at 5e-8mbar 50mA.h/m 2,5 2 Thickness (um) 1,5 1 0,5 Gold Distance to center (mm)

6 Sputtering Simulation Results Gold cathodes (-16, 16 mm) Thickness (um) 2,5 2 1,5 1 0, Distance to center (mm) Vanadium sputtering from 3 cathodes at ( 19, 0, 19 mm) N. Particles Distance to center (mm) 5.00E E E 03

7 Sputtering Simulation Issues N. Particles e-3 1e-2 8e Distance from center (mm)

8 Pressure Bursts

9 Simulation of a pressure burst in an ID

10 Electrical circuit equivalent R21 {NEG} NEG1 {Q} I1 R12 R22 {NEG} NEG2 {Q} I2 R13 R23 {NEG} NEG3 {Q} I3 R14 R24 {NEG} NEG4 {Q} I4 R15 R25 {NEG} NEG5 {Q} I5 R16 R26 {NEG} NEG6 {Q} I6 R17 R27 {NEG} NEG7 {Q} I7 R18 R28 {NEG} NEG8 {Q} I8 R19 R29 {NEG} NEG9 {Q} I9 R10 R20 {NEG} NEG10 {Q} I10 R111 R211 {NEG} NEG11 {Q} I11 R112 {NEG} NEG12 {Q} I12 PUMP1 82L/s PUMP2 82L/s NET2 NET3 NET4 NET5 NET6 NET7 NET8 NET9 NET10 NET11 NET12 NET13 NET14 NET1 NET7b R11 R212 CV6000 Chamber 250mm sections {V} V1 {V} V2 {V} V3 {V} V4 {V} V5 {V} V6 {V} V7 {V} V8 {V} V9 {V} V10 {V} V11 {V} V12 I? IPULSE

11 Spice results 2,50E-05 2,00E-05 Pressure (mbar) 1,50E-05 1,00E-05 5,00E ,00E Length (cm)

12 Cell 30 Upstream CV6000 Downstream CV3 CV4 CV5 CV6 CV7 CV8 CV9 CV10 CV11 CV12 CV13 CV14 CV15 CV15 CV12 CV11 CV10 CV8 CV5 CV4 CV3 CV6000 CV3

13 CV 3 {2/50} CV3_R2 {506*Q_ss*T+0.256*Qx_CV3} CV3_Q1 CV3_1 {2/50} CV3_R CV3_V1 {1/200} CV3_Pump1 {1/239} CV3_C_pump1 {2/10.6} CV3_R4 {3062*Q_ss*T+1.550*Qx_CV3} CV3_Q2 CV3_2 {2/10.6} CV3_R3 3.5 CV3_V2 {1/75} CV3_Pump2 {1/239} CV3_C_pump2 {2/13.8} CV3_R6 {2300*Q_ss*T+1.164*Qx_CV3} CV3_Q3 CV3_3 {2/13.8} CV3_R5 2.6 CV3_V3

14 Difficult shapes

15 Simulated pressure profile (no beam) 1E-12 1E-11 1E-10 1E-09 1E-08 net2 net3 net4 net5 net6 net7 net8 net9 net10 net11 net12 net13 cv3_1 cv3_2 cv3_3 cv4_1 cv4_2 cv5_1 cv5_2 cv5_3 cv6 cv7 cv8_1 cv8_2 cv8_3 cv9 cv10_1 cv10_2 cv10_3 cv11_1 cv11_2 cv12_1 cv12_2 cv12_3 cv13 cv14 cv15_1 cv15_2 cv15_3

16 Cell 30

17 Cell 30 Pressure Profile (no beam) 1,0E-08 1,0E-09 Pressure (mbar) Exp 1,0E-10 1,0E-11 ip1 ip3 ip5 ip6 ip7 ip8 ip9 ip10 ip11 ip12 Ion pump reference

18 Cell 30 Pressure Profile (no beam) 1,0E-08 1,0E-09 Pressure (mbar) Exp Sim 1,0E-10 1,0E-11 ip1 ip3 ip5 ip6 ip7 ip8 ip9 ip10 ip11 ip12 Ion pump reference

19 Cell 18 Pressure Profile (no beam) 1,0E-08 1,0E-09 Pressure (mbar) Exp Sim 1,0E-10 1,0E-11 IP1 IP2 IP3 IP4 IP5 IP6 IP7 IP8 IP9 IP10 IP11 IP12 Ion pump reference

20 Adding beam effects Thermal load Beam mode / Current Photo desorption Conditioning

21 Thermal load Temperature C no beam 7/ / bunch

22 Filling modes 3,5E-09 3,0E-09 2,5E-09 Pressure (mbar) 2,0E-09 1,5E-09 1,0E-09 no beam 7/ / bunch 5,0E-10 0,0E+00 IP1 IP2 IP3 IP4 IP5 IP6 IP7 IP8 IP9 IP10 IP11 IP12 Ion pump reference

23 Adding photo desorption 1,0E-01 1,0E-02 1,0E-03 (mol/ph) 1,0E-04 1,0E-05 1,0E-06 Bakeout Activation c 1,0E-07 1,0E+18 1,0E+19 1,0E+20 1,0E+21 1,0E+22 1,0E+23 1,0E+24 D' (ph/m)

24 Usual procedure for new machines Estimate total photon flow 90% stopped in the absorbers and 10% lost to chamber walls Using a PSD yield of mol/ph to estimate a total gas load

25 Cell 30 pressure profile simulation It is difficult to make these simulation work in a machine that has been in service for long. Nevertheless it may be helpful to have a reference to which to compare against real data

26 ESRF users demands

27 ESRF users demands Chamber surface area: cm mbar/l/cm 2 Q = mbar/l!

28 Summary Vacuum modeling is fundamental to the services provided by the vacuum group. No single tool, or technique, can provide all the answers to the demands of ESRF accelerator and its users To model the accelerator vacuum profile, knowledge of surface outgassing, specially in dynamic conditions, seems more important than a accurate model of the vacuum system