1. Dynamic vacuum zero-order Dynamic vacuum requirement H 2 and CO 2 partial pressures < 1 nTorr (G. Rumolo and D. Schulte) BD meeting1Sergio Calatroni - 24.3.2010

2. From Cedric BD meetingSergio Calatroni - 24.3.20102 !!!! Based on outgassing (H 2 O): 10 -10 mbar.l.sec -1 cm -2 for 100h pumping (Paolo’s vacuum course: 2*10 -11 for 100 h)

3. Structure test layout BD meetingSergio Calatroni - 24.3.20103 e - on faraday cup

4. Model Only one cell is modelled Electrons are field-emitted, then accelerated and distributed uniformly in the cell Dynamic vacuum by ESD: desorbed molecules fill the whole cell volume, or only the “beam channel” No pumping BD meetingSergio Calatroni - 24.3.20104 e - on faraday cup e - are uniformly distributed inside the cell e - on faraday cup Cell [mm]dimensionsouter areabeam areacopper areavolume [mm3]beam channel [mm3] Ext diam201086.9928.271030.442293.36206.40 Iris diam6 volume [liters]beam channel [liters] Length7.3 2.29E-032.06E-04

5. Faraday cup measurements - T18_VG24_Disk_2 - KEK BD meetingSergio Calatroni - 24.3.20105 Pulse 173 ns

6. ESD data No much data on unbaked copper (N. Hilleret, CAS Vacuum School 2006 - G. Vorlaufer CERN-Thesis (2002) ) BD meetingSergio Calatroni - 24.3.20106

7. Data BD meetingSergio Calatroni - 24.3.20107 Total e- current [A]Pulse duration [ns]Total charge [C]Number of electrons Solid angle (one cell, one side) Total electrons on copperDose per pulse (e- /cm2) 1.00E-042002.00E-111.25E+080.0274390244.56E+094.42E+08 ESD coefficient for H2 (unbaked copper) Total H2 molecules per RF pulse Equivalent pressure at RT (total volume) Equivalent pressure at RT (beam channel)G. Vorlaufer CERN-Thesis (2002) 2.00E-019.11E+081.12E-081.25E-07 ESD coefficient for CO2 (unbaked copper) Total CO2 molecules per RF pulse 6.00E-022.73E+083.37E-093.74E-08 ESD coefficient for H2 (copper baked 250 C) Total H2 molecules per RF pulse 250 C / 24h Benvenuti et al LEP2 94-21 1.30E-025.92E+077.29E-108.11E-09 ESD coefficient for CO2 (copper baked 250 C) Total CO2 molecules per RF pulse 6.00E-032.73E+073.37E-103.74E-09 ESD coefficient for H2 (copper baked 300 C) Total H2 molecules per RF pulse Mathewson-JVSTA15(1997)3093.pdf 3.00E-031.37E+071.68E-101.87E-09 ESD coefficient for CO2 (copper baked 300 C) Total CO2 molecules per RF pulse 1.60E-037.29E+068.98E-119.98E-10 10 7 pulses to start conditioning 10 -100 times maximum allowed 3 -30 times maximum allowed

8. Molecule speed BD meetingSergio Calatroni - 24.3.20108 Atomic massMass [kg] Molecule speed @ 300 K [m/s] Molecule displacement in RF pulse [m] H223.32E-271579.2326953.16E-04 H2O182.988E-26526.41089821.05E-04 CO284.648E-26422.06769128.44E-05 CO2447.304E-26336.69354186.73E-05

9. Mauro’s vacuum course BD meetingSergio Calatroni - 24.3.20109

10. Water desorption due to pulsed heating RF pulse duration = 10 -7 s >>  =1/ 0 = 10 -13 s Desorption depends on the sojourn time as a function of temperature Pulse heating: 300 K  350 K (  T ≈ 50 K) Sojourn time: 6 s  0.06 s Dynamic desorption : 10 -11 mbar.l.sec -1 cm -2  10 -9 mbar.l.sec -1 cm -2 BD meetingSergio Calatroni - 24.3.201010 Desorbed flux [mbar.l.sec-1cm-2]Pulse duration [s] Specific amount [mbar.l.cm-2] Total amount [mbar.l] Equivalent pressure cell [mbar] Equivalent pressure beam [mbar] 1.00E-092.00E-072.00E-162.06E-158.99E-139.98E-12